Sustainable A - Mr. Skerrett

A

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SustainableEcosystemsSustainableEcosystems

Northern leopard frogslike this one were oncecommon in lakes andponds across NorthAmerica. In NorthAmerica and around theworld, populations offrogs and toads havebeen decreasing.Scientists view thisgradual disappearance asa sign that the ecosystemsthese creatures are partof are in trouble.

U N I T

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Unit Task

You will be part of a team that is designing a totallysustainable community to be built in your area. You willlook into how resources are currently used in your area and research ways to lessen the impact on yourlocal ecosystems.

Essential QuestionHow do human activities, both positive and negative,affect the sustainability of ecosystems?

Ecosystems are complex, self-regulatingsystems of organisms and theirabiotic environments.

1.1 Ecosystems

1.2 Nutrient Cycles and Energy Flow

1.3 Interactions in Ecosystems

Human activity affects the sustainability ofecosystems.

2.1 Human Use of Ecosystems

2.2 Assessing the Impact of Human Activities onEcosystems

Governments, groups, and individuals workto promote sustainable ecosystems.

3.1 Government Action to Protect Canada’sEcosystems

3.2 Environmental Stewardship DI

DI

DI

Contents

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2

3

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Cootes Paradise lies on the edge of the city of Hamilton.

Cootes ParadiseThe lush green of Cootes Paradise bumps up against the hard edgeof the city of Hamilton. Cootes Paradise is a wetland locatedbeside the city of Hamilton. A wetland is an area in which thesoil is saturated with water for at least part of the year. Wetlandsprovide a home for many different species of fish, plants, insects,and birds. Many people also use wetlands for camping, fishing,and wildlife viewing.

Pollution and urban development have affected CootesParadise, but another factor has taken a toll on the wetland —carp. These fish feed in the shallow waters by pulling up the rootsof water plants, damaging the plants and muddying the waters asthey go. This makes it difficult for water plants and other fishspecies to survive. By 1985, almost 85 percent of the wetland’svegetation had disappeared. This was never supposed to happen.

In the 1800s, the federal government stocked the Great Lakeswith carp, a fish that is native to Asia. But adult carp have fewpredators in the Great Lakes, and their populations exploded. Asmany as 50 000 adult carp used to feed and spawn each year inCootes Paradise.

4 UNIT A Sustainable Ecosystems

Exploring

By 1985, almost 85 percent of thewetland’s vegetationhad disappeared.

Carp like this one invaded CootesParadise.

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5Exploring

A1

Pesticide Use Across the Country

Pesticides are substances used to kill pests, such asdandelions or grubs. Some pesticides do not breakdown quickly, and they may enter local streams andwetlands, killing wild organisms. In response, somecommunities have banned the use of pesticides onlawns and gardens.

1. Work with a partner to analyze the informationabout pesticide use contained in the graph. Usethe following questions as a guide.

(a) Over what span of time does the graph showpesticide use?

(b) Why does each region show two bars?

(c) Which one of the regions on the graph is theaverage of all of the other regions?

(d) Which province had the highest pesticideuse in 1994? in 2006?

(e) Which province had the lowest pesticide usein 1994? in 2006?

(f) What percentage of households usedpesticides in New Brunswick in 1994?

(g) Which province did not change pesticide useover the period of the study?

(h) Did pesticide use in Canada increase ordecrease between 1994 and 2006?

2. An important skill is inferring information from agraph. Consider the following questions.

(a) One province put strict limits on pesticideuse on lawns after 1994. Infer from thegraph which province did this. Be preparedto explain your inference.

(b) In 2006, more pesticide was used in Ontariothan in Manitoba, Saskatchewan, andAlberta combined. How is this possible giventhe data in the graph?

3. Banning pesticides may have benefits. Are thereany drawbacks to banning pesticides? Are thereany people or organizations that might notwelcome a pesticide ban? Explain why.

Science, Technology, Society, and the EnvironmentSTSE

Households Using Pesticideson Lawn or Garden

Cana

da a

nd P

rovi

nces

503020Percent

40100

BC

AB

SK

MB

ON

QC

NB

NS

PE

Canada

NF

20061994

Pesticide use by Canadian households

Taking ActionIn 1993, the municipal government of Hamilton and the localcommunity joined together to take on the challenge of restoringCootes Paradise. One of the many things they did was to install afishway at the entrance to Cootes Paradise. It allows small fish toenter the wetland but prevents large fish from entering. The largefish are then captured and inspected. Wetland fish species arereturned to Cootes Paradise, but adult carp are not. The fishwayproject has been a tremendous success, and wetland plant and fishspecies are recovering.

The fishway at the mouth of CootesParadise

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1 Ecosystems are complex, self-regulating systems of organisms and their abiotic environments.

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Ecosystems are complex, self-regulating systems of organisms and their abiotic environments. 7

This woodchuck and the wildflowers are parts of acomplex ecological system, a meadow.

Skills You Will Use In this chapter, you will:

• interpret data from undisturbed and disturbed ecosystemsand graph the results, and explain the importance ofbiodiversity for all sustainable ecosystems

Concepts You Will LearnIn this chapter, you will:

• describe the complementary processes of photosynthesisand cellular respiration with respect to the flow of energyand the cycling of matter within ecosystems, and explainhow human activities can disrupt the balance achieved bythese processes

• describe the limiting factors and explain how these factorsaffect the carrying capacity of an ecosystem

• identify Earth's four spheres (biosphere, hydrosphere,lithosphere, and atmosphere), and describe how thesespheres interact to maintain sustainability and biodiversity

Why It Is ImportantThere are many different ecosystems on Earth. If we knowhow an ecosystem functions as a system, we can analyzehow human activities sometimes disrupt ecosystems andmake them unsustainable. We can then help to repair orrestore ecosystems.

Visualize to Understand

Good readers picture words and whole phrases of text intheir minds. Preview the key terms and mainsubheadings in section 1.1, and use the words or partsof words you know to begin constructing a picture ofecosystems.

Key Terms

• abiotic • atmosphere • biodiversity • biosphere • biotic• carrying capacity • cellular respiration • energy pyramid• equilibrium • hydrosphere • limiting factor • lithosphere • nutrient cycle • photosynthesis • population

Before Reading

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Planet EarthHigh above the planet, the International Space Station offers abreathtaking view of Earth (Figure 1.1). Canadian astronaut DaveWilliams has been privileged to see that view first-hand. Afterreturning to Earth, he had this to say about his experience:

“I am truly in awe of the beauty of the planet, and it’ssomething I’ve been able to experience in so many differentenvironments, whether in space, underwater, camping,hiking, climbing mountains, or whatever. For me, it generatesa sense of planetary stewardship.”

Stewardship is a way of acting that involves taking personalresponsibility for the management and care of something.Planetary stewardship means working to take care of the wholeworld. A more common term for this is environmentalstewardship. The environment is all the living and non-livingthings that exist on Earth as well as their interactions with eachother. The beautiful blue sphere that astronauts have photographedfrom space helps us to remember that the resources in ourenvironment are limited. All life depends on what is contained onthat sphere. While the view from space is new to us, the idea of theimportance of environmental stewardship is far from new.


Here is a summary of what youwill learn in this section:

• Systems have components thatinteract.

• Ecosystems are systems withabiotic and biotic componentsthat interact.

• Ecosystems combine to formbiomes, and the biospherecontains all the biomes onEarth.

• The biosphere is composed ofthe atmosphere, the lithosphere,and the hydrosphere.

Ecosystems

Figure 1.1 A view of Earth from space

1.1

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Many cultures, especially those with a history of living close tothe land, hold a deep respect for the natural world. For example,Cree and other First Nations teach that the members of eachgeneration must be careful stewards of the Earth to ensure thesurvival of at least the next seven generations. For this to bepossible, the natural environment must be used in a sustainableway. Sustainability in the environment means that populations ofplants, animals, and other living organisms can continue to interactand to reproduce indefinitely. It also means that biodiversity ispreserved. Biodiversity is the number of different types oforganisms in an area. The more types of organisms there are in anarea, the more biodiversity the area has. High levels of biodiversityare associated with a healthy, sustainable environment.

9Ecosystems are complex, self-regulating systems of organisms and their abiotic environments.

A2 Quick Lab

Representing Earth’s Biodiversity

There are many different types of organisms on Earth.To study Earth’s biodiversity, similar species are placedinto categories. For example, foxes, bears, and micecan be grouped under “mammals.” In this activity, youwill make a visual representation of the 14 categories oforganisms shown in Table 1.1.

PurposeTo visually represent the numbers of each group oforganisms living on Earth

Procedure

1. Work with a partner to brainstorm a method ofrepresenting the numbers of each type oforganism in a visual way. It may be a two-dimensional representation such as a graph, or athree-dimensional model.

2. Once you have decided on a method, check withyour teacher, and then create yourrepresentation.

Questions

3. Look for and try to explain any relationship youcan find between the numbers of species in agroup and the type of organisms that are in thatgroup.

4. Compare your representation with that of otherstudents in your class. Which features of eachmodel did you like best, and which could beimproved?

5. How could you improve your representation?

WORDS MATTER

“Bio-” is a prefix derived from theGreek word bios, which means life.

Category Number of Species

Mammals (e.g., deer) 4 500

Reptiles and amphibians (e.g., snake, frog) 10 500

Fish (e.g., trout) 22 000

Crustaceans (e.g., shrimp) 40 000

Molluscs (e.g., clam) 70 000

Sponges (e.g., glass sponge) 10 000

Birds (e.g., crow) 10 000

Insects (e.g., fly) 963 000

Arachnids (e.g., spider) 75 000

Plants (e.g., cherry tree) 270 000

Fungi and lichens (e.g., mushroom) 100 000

Table 1.1 Earth’s Biodiversity

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Systems in the Environment Imagine a wild bee moving from flower to flower on a spring day.The bee busily visits many flowers, then, suddenly, it darts back to itshive (Figure 1.2). There, it unloads the tiny drop of nectar that it hasgathered on its journey. This activity seems very straightforward: thebee is simply collecting food for itself and its hive.

However, there is something more to this interaction betweenthe bee and the flower. Producing flowers and nectar takes a lot ofenergy and resources. Yet flowering plants produce vast numbersof colourful and fragrant flowers, each stocked with nectar toattract bees and other animals.

The answer is that pollinators such as bees help plants toreproduce. In order to produce seeds, most flowers need to befertilized with pollen from another plant. The plants cannot moveto get the pollen. That is where bees and other pollinators come in.When a bee visits a flower to get nectar, pollen sticks to its fuzzycoat. When it visits another flower, the pollen on its coat fertilizesthe flower. Once fertilized, the flower can produce seeds, whichwill eventually grow into the next generation of plants.

Systems Have Components and InteractionsA bee fertilizing a flower is an example of an interaction betweendifferent organisms. Such interactions are not always positive. Ifyou have ever been stung by a bee, then you know that theinteraction between you and the bee is painful. The bee also diesonce it has stung you. It may seem that you and the bee both lose


Figure 1.2 Bees visit flowers to collect nectar, which they convert into honey at the hive.

Little Pictures Lead to theBig Picture

The story of the bee helpsyou to understand the largerpicture of how organismsinteract within a system.Draw and label a picture inyour mind as you read aboutthe bee, the hive, andflowering plants. How doesthis picture help you tounderstand the concept ofecological systems?

During Reading

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Figure 1.3 The wheels, chain, pedals,and the rider interact to perform atask: movement.

in this interaction, but this is not necessarily the case. The beemay have successfully defended its hive by encouraging you tomove away from the area. You may even have benefitted if thesting prevented you from accidentally walking right into the hive,risking hundreds more stings.

A system is a group of individual parts that interact as awhole to accomplish a task. The parts of a system are calledcomponents. For example, a bicycle is a mechanical system(Figure 1.3). All of the components of a bicycle interact to dosomething that none of the parts can do alone, which is to movethe rider along a road.

Systems exist in the natural world as well. Returning to thebee example, think of all the interactions that happen in the life ofa worker bee. The worker supports the hive by building it,bringing in nectar, or defending the entrances to the hive. Theseinteractions give the drones, the male bees, a place to live untilthe queen bee needs to mate with them. The queen bee’s role is toproduce eggs. Each bee is driven by instinct to perform varioustasks. The result of all the individual bees’ interactions is acomplex and self-sustaining system: the hive.

A Holistic ApproachAlthough ecologists have to identify the components of ecologicalsystems, such as water temperature and the number of fish, theyalso have to take a holistic approach as well. In a holisticapproach, the entire system is emphasized. If you took a bicycleapart and just looked at all the pieces, you could know everythingabout all the parts and yet still not know that a bicycle’s functionis to move a rider along a road (Figure 1.4). This is because“riding” is not something that has meaning toany of the individual parts. It has meaning onlywhen the system — all the bicycle parts,including the rider — is considered as a whole.The same is true in the study of theenvironment.

Many Aboriginal ways of knowing have longtaught the importance of a holistic approach tothe environment. Many Aboriginal peoplebelieve that everything is connected throughinteractions. They also take the view that we areall part of the environment that we live in.These beliefs result in a deep respect for Earth.


Figure 1.4 The individual parts of a bicycle give you no clue abouthow they work as a whole.

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Traditional ways of living require that everything in nature, fromwater to organisms, be treated with respect and used wisely.

Ecological Systems Are ComplexEcology is the study of how organisms interact with each otheras well as with their environment. A person who studies ecologyis called an ecologist.

Consider, for example, how an ecologist might study a coralreef. Coral reefs are one of the world’s most important andsensitive ecological systems (Figure 1.5). An ecologist might wantto find out such things as which kinds of fish live therepermanently, and which stay for short periods and then leave.They might also study the physical parts of the system, such as theamount of salt dissolved in the water or the water temperature,and how they affect reef organisms.

Currently, ecologists are examining how reefs respond torising water temperatures. Early results suggest that warmerwater can be very harmful to a reef. It is often impossible topredict what will happen when one component changes becausethe components of the system are so interconnected. A coral reefhas a large number of components and an even larger number ofinteractions. Most ecological systems are similarly complex.


Figure 1.5 The more components a system has, the more complex the system becomes. A coral reef is a very complex system.

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Elements of EcosystemsAn ecosystem is a complex, self-regulating system in whichliving things interact with each other and with non-living things.Self-regulating means that the interactions keep the ecosystemhealthy and sustainable.

In order to analyze how ecosystems function, ecologistsclassify all parts, or factors, of ecosystems as either biotic orabiotic. Biotic factors are organisms, such as animals, plants,fungi, bacteria, and algae. Abiotic factors are everything else(Figure 1.6). Abiotic factors can be physical things, such as rocks,air, and water. Abiotic factors can also be things that aremeasured, such as air temperature, hours of daylight, and saltconcentration in seawater. It is the interactions of the biotic andabiotic elements that help keep the ecosystem self-regulating.


Figure 1.6 The abiotic components in this pond ecosystem include water, air, and deadbranches. The biotic components include reeds, bushes, and the duck.

Learning Checkpoint

1. Explain what is meant by each of the following terms.

(a) stewardship

(b) environment

(c) sustainability

(d) biodiversity

2. List three possible interactions between a bee and its environment.

3. What is meant by the term “system”? How are a bicycle and a rider a kind of system?

4. Ecology can be described as a holistic science. Explain why this isthe case.

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Ecosystems Have CommunitiesA species is a group of similar organisms in an ecosystem.Members of a species can reproduce with each other, and theiroffspring can reproduce. For example, the grey squirrel iswidespread throughout Ontario (Figure 1.7 (a)). All greysquirrels are members of the same species. They can reproducewith each other but not with red squirrels, which also live inOntario. A population is a group of members of the samespecies that live in the same area (Figure 1.7 (b)). The physicalenvironment of an organism is its habitat.

All grey squirrels are part of the same species, but they are notall part of the same population. For example, one group of greysquirrels might live in a pine forest, while another might live in apark in the next valley over. These two groups of squirrels aretwo different populations.

A community is made up of populations of different speciesthat live and interact in an area. For example, a park containspopulations of squirrels, robins, trees, and shrubs (Figure 1.8).The interactions of the populations with each other and with thelocal abiotic factors make up the ecosystem.

All the interactions of a given species with its ecosystem formthe species’ niche. For example, the niche of grey squirrels


Figure 1.8 Populations of differentspecies living in the same area forma community.

Suggested Activity •A3 Quick Lab on page 20

Figure 1.7 (a) A single grey squirrel is a member of the grey squirrel species. (b) A group ofgrey squirrels living in the same area form a population.

(b)(a)

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Figure 1.9 If the bacteria in the dropof water interact with the water, light,and other abiotic factors, the drop isan ecosystem, even though it may betemporary.

includes eating nuts and other seeds, being hunted by foxes andowls, being active during the day, and living and nesting in trees.

Ecosystems Come in All SizesEcosystems vary widely in size. They can be as tiny as a drop ofwater or as large as a desert or an entire ocean. The size of anecosystem is not the most important thing about it. What reallymatters for it to be sustainable is that it is a complete system.

Consider a single drop of water resting on the needle of a firtree (Figure 1.9). This drop contains millions of tiny organisms,such as bacteria and microscopic algae. These are the bioticcomponents of the ecosystem. The drop contains matter that thebacteria absorb to help them live. The drop also receivessunlight, which is a source of energy that makes it possible forthe bacteria to use the matter and to grow. Matter and sunlightare some of the abiotic components of the ecosystem. Even asnew bacteria are produced, others die. The matter in the deadbacteria can be recycled. The recycled matter then providesnourishment for the living bacteria.

There can be many interactions between biotic componentsin the drop. For example, there are probably many differentkinds of bacteria in the drop, and they often compete with eachother for resources. Some bacteria may eat other bacteria. Othertypes of bacteria may group together under difficult conditions,such as when the water drop dries out between rainfalls.

Ecosystems Combine to Make BiomesEcosystems can exist within largerecosystems. For example, a stream iscomposed of fresh water, rocks,crayfish, fish, and various types ofplants. All these abiotic and bioticfactors interact as a unit. Suppose,however, that this stream runs througha forest (Figure 1.10). Animals that livein the forest drink and catch fish fromthe stream, and certain trees, such ascedars, grow along the banks of thestream. Because the forest plants andanimals interact with the streamecosystem, the stream is also part of theforest ecosystem. A single rotting log on


Figure 1.10 This forest ecosystem contains a stream ecosystem and manyother smaller ecosystems.

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the forest floor is an ecosystem as well because the organisms thatlive in or on the log interact with one another and with the non-living log. It too is part of the forest ecosystem.

All these ecosystems are interconnected. The forest ecosystemis part of a larger region that contains many similar forests.Similarly, the small stream feeds into a larger river, which isanother ecosystem. The river eventually feeds into an ocean,which contains many more ecosystems.

A biome is a large geographical region that contains similarecosystems. On land, biomes are defined by the types of plants thatgrow in them. They are also classified according to the averagetemperature and the amount of rainfall. Because the ecosystems ina biome usually have similar plants, animals, and weather and


(a)

(c) (d)

(e)

(b)

Figure 1.11 Canadian terrestrial biomes include (a) deciduousforest, (b) boreal forest, (c) tundra, (d) grassland, and (e) temperateconiferous forest. Abiotic factors, such as the amount of rainfall andthe average temperature, determine what types of vegetation exist ineach biome.

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receive similar amounts of precipitation, it can be very helpful inthe study of an ecosystem to know which biome it is in. Biomesare often divided into those on land and those in water.Throughout the world there are many types of biomes. In Canada,there are five major land, or terrestrial, biomes (Figure 1.11).

Terrestrial BiomesCanada’s five main terrestrial biomes are defined by theirdominant vegetation.

• Deciduous forests have trees that lose their leaves in theautumn, such as maples and oaks. Southern Ontario ismainly a deciduous forest biome.

• Boreal forests (also known as taiga) have trees that havecones and needles, such as spruce and fir. Most of northernOntario is covered with boreal forests.

• Tundra has no trees, only small shrubs, hardy grasses,mosses, and lichens. Even some flowers such as crocusesgrow here. Ontario’s northern coastline on Hudson Bay, tothe west of James Bay, is tundra.

• Grasslands have few trees but are covered in various kindsof grasses and shrubs. Ontario has very few grasslands.They are found in Manitoba, Saskatchewan, and a smallpart of Alberta.

• Temperate coniferous forests have different types ofneedle- and cone-bearing trees than the boreal forest: Douglasfir, Sitka spruce, and western hemlock. Most of westernBritish Columbia is temperate coniferous forest.

Aquatic BiomesWater-based, or aquatic, biomes fall under two main categories:marine and freshwater (Figure 1.12). The water in marinebiomes has a high salt content, and the water in freshwaterbiomes has a very low salt content.

• Marine biomes are found in the oceans. Coral reefs, theocean floor, the open ocean, and the intertidal zones aremarine biomes. Ontario has marine biomes along HudsonBay and James Bay.

• Freshwater biomes include lakes, streams, rivers, andwetlands. Some of Ontario’s lakes and rivers are huge, suchas the Great Lakes and the St. Lawrence River. Ontario hascountless smaller lakes, streams, and wetlands.


Figure 1.12 Two aquatic biomes. (a) A lake is a freshwater biome. (b) The open ocean of Hudson Bayis a marine biome.

(a)

(b)

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Biomes Combine to Make the BiosphereThis section began with a view of Earth from space. With thewhole planet in view, the idea of promoting stewardship andsustainability becomes urgent because we can see that theresources of Earth are limited. We also now know that Earth’sbiotic and abiotic factors interact in ecosystems. Ecosystems canbe large or small, and they overlap and interconnect.

The very largest of these ecosystems, the biomes, combine tomake a planetary system. It is the most important system onEarth, and it is our home. It is called the biosphere (Figure 1.13).

The biosphere is the part of the planet, including water, land,and air, where life exists. It is very thin relative to the wholeEarth. If Earth were represented by a beach ball, the biospherecould be represented by a sheet of plastic wrap laid over itssurface one layer thick. Three main interacting components makeup the physical environment of the biosphere. They are theatmosphere, the lithosphere, and the hydrosphere (Figure 1.14).


30˚N

60˚N

30˚S

60˚S

equator 0˚

0 1500 3000 km

N

tropical rainforest

tropical dry forest

tropical savanna

temperate grassland

desert

temperate woodlandand shrubland

temperate deciduous forest

boreal forest (taiga)

temperate coniferous forest

tundra

mountains and icecaps

Figure 1.13 Earth’s major terrestrial biomes. These biomes, plus the ocean biomes, contain all life on Earth. The biosphere is the part of Earththat contains all the world’s biomes.

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Around the world there are several other major types ofterrestrial biomes, including moreforest biomes. Find out moreabout the world’s biomes. Beginyour research at ScienceSource.

Take It Further

• The atmosphere is the layer of gases that surrounds Earth.Water vapour and carbon dioxide in the atmosphere absorbsunlight and retain the Sun’s energy as heat, warming theplanet to temperatures suitable for life. The loweratmosphere contains oxygen, which many organisms needto survive, while the upper atmosphere contains a differentform of oxygen called ozone. Ozone protects organisms inthe biosphere from the Sun’s harmful ultraviolet radiation.

• The lithosphere is Earth’s solid, outer layer. It includes therigid crust and the upper mantle, which lies directly belowthe crust. The lithosphere extends 100 km down from thesurface and runs under the continents and oceans. Itincludes the soil, which is home to many micro-organisms,plants, animals, and fungi.

• The hydrosphere is all the water on Earth. About97 percent of this water is salt water in Earth’s oceans. Theother 3 percent is fresh water and includes water in lakesand streams and the ice and snow in glaciers. All livingorganisms need water, and so they depend on thehydrosphere.


atmosphere

biospherelithosphere

hydrosphere

Figure 1.14 The biosphere is composed of all living things on Earth and the physicalenvironment that surrounds them.

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A3 Quick Lab

A forest and a flower garden are located in the samearea. One is a natural ecosystem, and the other is anartificial ecosystem.

PurposeTo determine the differences between artificial andnatural ecosystems

Procedure

1. Create a tally chart like the one in Figure 1.17.

2. Examine the forest ecosystem in Figure 1.15.For each species you find, put a tally mark in thetally chart.

3. Repeat step 2 for the garden ecosystem in Figure 1.16.

4. Create a bar graph that shows both the garden’sand the forest’s biodiversity.

Questions

5. Which ecosystem has more biodiversity? How doyou know?

6. What things do you think humans do in theflower garden to alter the abiotic elements of theecosystem? What effects do these actions have,if any, on biodiversity?

7. What things do humans do in the flower gardenthat alter the biotic elements of the ecosystem?What effects do they have on biodiversity?

Natural Versus Artificial

Figure 1.15 A forest Figure 1.16 A flower garden

Figure 1.17

Forest Garden

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Key Concept Review1. What is an ecosystem?

2. What is biodiversity a measure of?

3. What are the characteristics of a sustainableecosystem?

4. Do biomes contain ecosystems, or doecosystems contain biomes? Explain youranswer.

5. What is ecology?

6. What is the difference between a biotic andan abiotic component of an ecosystem?

7. How do marine biomes differ fromfreshwater biomes?

8. Explain what a population is.

9. What are the three components thatsupport the biosphere?

Connect Your Understanding10. You interact with abiotic and biotic parts of

your environment every day.

(a) List five abiotic factors in yourenvironment.

(b) List five biotic factors in yourenvironment.

11. What abiotic factors may affect the growthof an oak tree in an Ontario forest?

12. If you travelled north from southernOntario to the Arctic, you would passthrough several biomes. How would thevegetation change during this trip?

13. A stream is an aquatic ecosystem, but it canalso be part of a forest ecosystem at thesame time. Explain how this is possible.

14. Our planet has been referred to asSpaceship Earth. Explain how this might bean effective way to describe our planet.

15. Examine the ecosystem in the photographbelow.

(a) Identify three abiotic factors that arepart of this ecosystem.

(b) Identify three biotic factors that are apart of the ecosystem.

16. An analogy is a comparison between twodifferent things that are alike in some ways,but different in others. In this section, abicycle was an analogy used to identifysome of the characteristics of an ecosystem.Create another analogy that shows some ofthe characteristics of an ecosystem.

17. Ecologists must understand the componentsthat make up an ecosystem. Ecologists haveto take a holistic view. Explain how both ofthese statements are true.

Reflection18. Describe three things you did not know

about ecosystems before you startedworking on this chapter.

For more questions, go to ScienceSource.


Question 15

1.1 CHECK and REFLECT

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A Great MigrationAt the end of each summer in Tanzania, Africa, a great migrationbegins. Over 1 million wildebeests move across the SerengetiPlain in search of food. They move north to Kenya, where rainshave watered the plain and lush grasses have emerged from themoist soil. The wildebeests’ need for food is so strong that theyrisk their lives to swim across rivers to get to greener pastures

(Figure 1.18). Drowning is not the only danger. Thewildebeests also risk being eaten by crocodiles(Figure 1.19).

All organisms need food to survive. Animalsmust eat other organisms to survive. The wildebeestseat grasses, and the crocodiles eat some of thewildebeests. Grass and wildebeests are examples offood. Food contains nutrients. Nutrients aresubstances that an organism uses to build and repairthe cells of its body. Plants generally draw nutrientsup from the soil and extract them from the air. Theyuse sunlight and nutrients to make their own food.In addition to nutrients, food contains energy, whichall organisms need to grow and maintain their bodiesand to reproduce.



• Nutrients move throughecosystems in cycles.

• Energy enters ecosystemsthrough photosynthesis, istransferred through cellularrespiration, and is eventuallylost as heat.

• Producers, consumers, anddecomposers are relatedthrough food webs and energypyramids.

Nutrient Cycles and Energy Flow

Figure 1.18 The wildebeests are wary of the dangers hidden in the water.

1.2

Figure 1.19 Crocodiles remain under the surface of the cloudy water and ambush wildebeests that enter the water.

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When a crocodile eats a wildebeest, some of the matter in thewildebeest becomes part of the crocodile. When the crocodile dies,some of its body ends up becoming part of the soil. Since grassesget some of their nutrients from the soil, the matter has come fullcircle. However, energy usually enters the ecosystem as sunlightand leaves it as heat. It is not recycled.


A4 Quick Lab

Finding the Relationships Among Organisms

PurposeTo determine the relationships among organisms

Procedure

1. Study the organisms shown in Figure 1.20.Create a mind map to show how these organismsrelate to one another. Once you have finished,share your map with a partner and explain whyyou made the connections you did.

Questions

2. Which organisms have the most connections inyour mind map?

3. A photo of one very important component ismissing. Can you figure out what it is?

4. Remove one of the organisms from your mindmap. Describe the ways this would affect thecommunity of organisms.

Figure 1.20

4400�

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Nutrient CyclesThe nutrients in the food you eat provide energy and matter thatyour body needs to stay alive. Every living organism needsnutrients to carry out life functions. Nutrients includecarbohydrates, fats and oils, proteins, vitamins, and minerals(Table 1.2).

Nutrients are made up of elements, which are puresubstances that cannot be broken down into simpler substances.For example, sugar, a carbohydrate, is made from the elementscarbon, oxygen, and hydrogen (Figure 1.21). Water is made fromthe elements oxygen and hydrogen. The element nitrogen is apart of proteins. In fact, 95 percent of our bodies are made up ofjust four elements: carbon, oxygen, hydrogen, and nitrogen.

Humans and other animals obtain the carbon, hydrogen,oxygen, and nitrogen they need from eating carbohydrates, fats,and proteins. Plants obtain them by absorbing carbon dioxide fromthe air and water and substances called nitrates from the soil.

Nutrients cycle back and forth between the biotic parts ofecosystems (organisms) and the abiotic parts of ecosystems. Theprocess of moving a nutrient back and forth is called a nutrientcycle. For example, carbon dioxide is exhaled by a wildebeest.The carbon contained in the carbon dioxide is now in theatmosphere, an abiotic part of the ecosystem. The carbon dioxideis then absorbed by a grass plant, and the carbon particle itcontains becomes part of a carbohydrate in the grass’s cells. Thecarbon is now once again in the biotic part of the ecosystem.

Sometimes matter can cycle back and forth between the bioticand abiotic parts of an ecosystem fairly quickly. Sometimesmatter can remain in one place for a long time. For example, theice in glaciers has been there for thousands of years. Any placewhere matter accumulates is called a reservoir. The cycles thatwater, carbon, and nitrogen follow all have reservoirs.

The Water Cycle Water is a substance that moves in a cycle. A cycle has nobeginning or end. In the water cycle, water is moved throughoutthe whole biosphere. The Sun’s heat warms the surface water,and the water evaporates into the atmosphere (Figure 1.22). Inthe atmosphere, the water exists as a gas, called water vapour.

As the water vapour cools, it condenses to form clouds. Fromthere, it may fall to Earth as rain, hail, snow, or sleet. If it falls tothe ground, it will tend to run off the surface into nearby streams


Figure 1.21 The sugar that makes anorange sweet is a carbohydrate.

Nutrient Examples

carbohydrate bread, rice, sugar

fats and oils butter, corn oil

protein beans, chicken

vitamins vitamin C, vitamin D

minerals calcium, potassium

Table 1.2 Examples of Nutrients


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or rivers. This water is called run-off. Some water seeps downthrough the soil into the ground water. Some ground water mayflow into large underground lakes, known as aquifers, whilesome may flow into other bodies of water such as wetlands or oceans.

Some of the water on the surface or in the soil is taken up byanimals and plants. Plants play a major role in the water cyclethrough a process known as transpiration. Transpiration occurswhen plants release water vapour into the atmosphere throughtheir leaves. The water vapour rises into the atmosphere, and thecycle continues.

The Nitrogen CycleAll organisms need nitrogen to make proteins. Nitrogen alsomoves in a cycle. Nitrogen gas makes up 78 percent of theatmosphere, but it cannot be used directly by most organisms.They get their nitrogen from substances such as ammonia thatcontain nitrogen. Converting nitrogen gas into ammonia is callednitrogen fixation. Nitrogen-fixing bacteria perform thiscritical step. Without these bacteria, movement of nitrogen wouldstop almost completely. Lightning is the only other naturalnitrogen-fixing process. It accounts for only about 1 percent ofthe world’s nitrogen fixation.


condensationprecipitation

run-off

seepage

lake

ocean

evaporation transpiration

ground water

rootuptake

aquifer

Figure 1.22 The water cycle

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Plants called legumes (peas, beans, and alfalfa) have noduleson their roots that contain nitrogen-fixing bacteria. The bacteriasupply usable nitrogen directly to the plant. Nitrogen-fixingbacteria also live freely in the soil and water (Figure 1.23). Mostplants cannot use the ammonia these bacteria produce.Nitrifying bacteria convert ammonia into nitrites and thennitrates, which plants absorb through their roots.

Animals get the nitrogen they need by eating plants oranimals. When animals digest proteins, a by-product is ammonia.Ammonia is toxic to animals, and they get rid of it in theirwastes. Bacteria and fungi in the soil break down the ammonia inwastes and dead organisms into nitrates and nitrites and releasethem into the soil where they can be absorbed by plants.Denitrifying bacteria in the soil convert nitrates back intonitrogen gas, which returns to the atmosphere.

The Carbon Cycle All living things contain carbon. Carbon dioxide gas containscarbon. Although carbon dioxide makes up only 0.04 percent ofthe gases in the atmosphere, it is from this that all plants get thecarbon they need to grow. For example, a tall oak tree is bothmassive and solid. A large portion of the matter in the tree ismade of carbon, and all of the carbon came from the atmosphere.The world’s forests are biotic reservoirs of carbon (Figure 1.24).


nitrogen-fixingbacteria in rootnodules of legumes

nitrogen-fixingbacteria in soil

nitrification

nitrogen in atmosphere

decomposers

ammonification

denitrifyingbacteria

nitrifyingbacteria

nitrifyingbacteria

uptake

nitrates

nitritesammonia

Figure 1.23 The nitrogen cycle

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A huge carbon reservoir sits underground locked up indeposits of coal, which are almost pure carbon, oil, and naturalgas which are mostly carbon combined with hydrogen. Thesedeposits were formed from the remains of huge forests that livedhundreds of millions of years ago. Because oil, natural gas, andcoal were formed so long ago, they are called fossil fuels.

The other abiotic carbon reservoir is the oceans. Carbondioxide dissolves in water. Marine organisms use the carbon fromthe dissolved carbon dioxide to build their tissues.

Many natural processes move carbon between these variouscarbon reservoirs. Two of the most important processes arephotosynthesis and respiration. Not only are both of theseprocesses central to nutrient cycles, they are also closelyconnected with the flow of energy through ecosystems.


fossil fuels

carbon compoundsin water

plants

burning offossil fuelsand wood

phytoplankton

primaryconsumers

higher-levelconsumers

decomposers

photosynthesis

photosynthesis

dead organisms

cellularrespiration

CO2 in atmosphere

Figure 1.24 The carbon cycle

Learning Checkpoint

1. Explain what is meant by each of the following terms.

(a) nutrient

(b) element

2. Give an example of the possible steps in a water cycle where water leavesan ocean, moves to land, and then returns to an ocean.

3. What are the types of bacteria involved in the nitrogen cycle?

4. List one biotic and one abiotic reservoir for the element carbon.

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Energy Flows Through EcosystemsThe ultimate source of energy for Earth’s ecosystems is the Sun.A small fraction of the sunlight that reaches Earth is absorbed bythe substance that causes plant leaves to be green. This substanceis called chlorophyll. Plants use chlorophyll to capture theenergy in sunlight and convert it into chemical energy. They thenuse the chemical energy for all the processes in their cells.

PhotosynthesisThe process plants use to capture the energy in sunlight iscomplex (Figure 1.25). Plants absorb the chemical carbon dioxidegas and combine it chemically with water to produce a thirdchemical called glucose. Glucose is actually a form of sugar. Allsugars are carbohydrates. Carbohydrates contain energy. Theprocess of producing carbohydrates from carbon dioxide, water,and sunlight is called photosynthesis.

Photosynthesis can be written out in the form of a shortstatement, usually called a word equation, as follows:

carbon dioxide gas + water + sunlight � glucose + oxygen gas


carbon dioxide fromthe atmosphere

water from the soil

Oxygen is releasedas a product ofphotosynthesis.

Photosynthesis

cells formglucose

light

oxygen

water

carbondioxideglucose

madein leaf

Light energydrives the reaction.

Sun

Figure 1.25 Photosynthesis

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Carbon dioxide gas and water are shown to the left of thearrow because they are being used, along with sunlight, tomake glucose and oxygen gas, shown to the right of the arrow.The plant releases some of the oxygen gas into the atmosphere,and it uses the rest of it to extract the energy from the glucose.The plant then uses the energy for the processes in its cells.

When you breathe, it is the oxygen gas in the air that keepsyou alive. About 21 percent of the atmosphere is made of oxygen,and almost all of it was produced through photosynthesis. Thetrees in the world’s forest biomes and algae in the marine biomesproduce most of the world’s oxygen (Figure 1.26).

Cellular RespirationPlants store the energy they capture from the Sun throughphotosynthesis in the form of glucose. However, plants need acontinuous supply of energy for functions such as growth, repair oftissues, and reproduction. The process plants use to obtain theenergy from the glucose is called cellular respiration. In cellularrespiration, glucose combines chemically with oxygen from the air,in what looks like almost the reverse of photosynthesis. Theequation for it is:

Plants use the energy released by cellular respiration for all theprocesses inside their cells.

Animals also carry out cellular respiration. Since they cannotcarry out photosynthesis, they must obtain glucose by eating foodcontaining carbohydrates. The equation also shows why we needto breathe. Breathing supplies oxygen needed for cellularrespiration (Figure 1.27).

glucose + oxygen gas � carbon dioxide gas + water + energy


Figure 1.27 When we breathe out, weare getting rid of carbon dioxide, oneof the products of cellular respiration.

Figure 1.26 Microscopic marinealgae

Learning Checkpoint

1. What is the role of photosynthesis in an ecosystem?

2. What substances are produced and consumed in photosynthesis?

3. How are photosynthesis and cellular respiration related?

4. Since plants can capture the energy of sunlight in photosynthesis, why doplants need cellular respiration?

300�

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Picture Mapping

As you read about producersand consumers, drawpictures with arrows toconfirm your understandingof how producers andconsumers connect.

During ReadingProducers and ConsumersProducers are organisms that carry out photosynthesis.Terrestrial and aquatic plants, algae, and other organisms areproducers. Producers are critical to ecosystems because they bringthe Sun’s energy into biological systems and turn it into chemicalenergy that plants can use.

Consumers are organisms that eat other organisms to obtainenergy because they cannot produce their own food. There areseveral types of consumers. For example, a caterpillar is aprimary consumer because it eats producers. A robin is asecondary consumer because it feeds on primary consumers.The third level of consumer, which eats secondary consumers, iscalled a tertiary consumer. For example, a hawk or eagle thatfeeds on a robin would be a tertiary consumer.

Because primary consumers always eat plants, they are calledherbivores. For example, moose and deer are herbivores. Otherconsumers eat meat. If they eat mostly meat, they are calledcarnivores. Scavengers are carnivores that eat the remains ofdead animals. Vultures are scavengers. Some consumers eat bothanimals and plants. They are called omnivores. Bears, raccoonsand many humans are omnivores. Detritivores are consumersthat feed on organic matter. Organic matter is the remains ofdead organisms and animal wastes. Earthworms and maggots aredetritivores.

Animals that catch and feed on other live animals are calledpredators. Animals that the hunter catches are called prey. Forexample, when a robin eats a worm, the robin is the predator andthe worm is the prey. However, if a hawk hunts a robin for food,then the robin is the prey.

Decomposers There is a group of special consumers called decomposers. Therole of decomposers is to break down organic matter and releasethe nutrients in the organic matter back into the ecosystem. Themajor decomposers are fungi and bacteria (Figure 1.28). They donot consume the organic matter directly. Instead, they releasespecial chemicals, called enzymes, into the organic matter tobreak it down. They then absorb the nutrients that are released.


Figure 1.28 This fungus is feeding on the organic matter in the soil. As it does, nutrients in theorganic matter are released into the soil.

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Food Chains and Food WebsFood chains are a way of showing feeding relationships amongorganisms. They start with a producer and end with a finalconsumer (Figure 1.29).

However, most consumers usually eat many different types offood. For example, a snowshoe hare eats willow, bog birch, andmany other green plants. A fox eats snowshoe hares as well assquirrels, voles, ptarmigan, and many other animals. Thesecomplicated feeding relationships can be modelled with a foodweb, as in Figure 1.30.


algae water flea damselfly nymph frog

Figure 1.29 An aquatic food chain

grey jay

great hornedowl

red fox

Canadian lynx grey wolf

redsquirrel

beetle

bunchberry

sprucegrouse snowshoe

hare

bog birch

moose

white spruce

Figure 1.30 This food web of aboreal forest shows how differentfood chains interconnect.

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Both food webs and food chains are limited in the informationthat they provide. They both clearly show who eats what, butthey do not show how much energy is being passed from oneorganism to the next. Energy pyramids help us understand theflow of energy through ecosystems.

Energy PyramidsGenerally, when an animal eats, 60 percent of the energycontained in the food cannot be accessed by the animal and itpasses out of the organism in its wastes (Figure 1.31). Thirtypercent of the energy is used to run cellular processes. Only about10 percent of the energy in the food is used to make body tissuessuch as bones, muscles, and fat. This is very important whentracing the path of usable energy through a food web. It meansthat only about 10 percent of the energy that the animal eats isavailable to pass on to an animal that eats it. Put another way, asenergy moves along a food chain, about 90 percent of the energyis lost at each transfer, most of it as heat.

Energy pyramids show the amount of available energy theproducers and consumers contain as energy flows through theecosystem (Figure 1.32). The more levels that exist between theproducers and the top-level consumer in an ecosystem, the lessenergy is left from the original amount provided by the producers.Energy pyramids also show how important producers are toecosystems. The wider the base of the pyramid, the more energyproducers provide to the consumers.


30 J

60 J

100 J eaten

stored in body tissue

10 J

passed out in waste used in body

processes

Figure 1.31 Of the 100 J thecaterpillar eats, only 10 J is storedin its tissues. Only the energy storedin the caterpillar’s tissues isavailable to the animal that eats it.

1 000 J

100 J

10 J

10 000 J

Figure 1.32 An energy pyramid shows the flow of energy through an ecosystem. The top levelshows the amount of energy from the bottom level that is still available.


Other types of ecological pyramids are pyramids ofnumbers and pyramids ofbiomass. Find out what thesepyramids model. Begin yourresearch at ScienceSource.

Take It Further

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A5 Quick Lab

Figure 1.33 demonstrates how nutrients cycle in anecosystem. Different nutrients all follow the samegeneral path.

PurposeTo observe the path of nutrients as they movethrough the atmosphere, lithosphere, hydrosphere,and biosphere

Procedure

1. With a partner, study Figure 1.33.

2. Discuss any patterns that you observe.

3. Even though a nutrient moves through theecosystem, there are certain locations where itmay be stored for a period of time. Identify theselocations.

Questions

4. Suggest the ways in which a nutrient moves:

(a) from the ocean to the atmosphere

(b) from the land to the ocean

5. If the ocean were removed from this diagram,how would this affect the flow of nutrients?

6. How do producers, consumers, anddecomposers contribute to nutrient cycles?

7. Notice that the arrows are all the same width.However, this is not a completely accuraterepresentation of nutrient flow. If a wide arrowrepresented a high level of flow and a thin arrowrepresented a low level of flow, which arrowswould you make thicker and which arrows wouldyou make thinner?

8. What abiotic factors do you think might affectthe cycle (temperature, wind, rain, sunlight)? Inwhat way would each one affect the cycle?

Analyzing Cycles

nutrient flows (exchanges)

natural processes

nutrient reservoirs

marine sediments and sedimentary rock

atmosphere

land

oceans

to deep stores(takes millions of years)

decomposers

producers consumers

decomposers

producers consumers

Figure 1.33 A general nutrient cycle

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A6 Quick Lab

PurposeTo create and compare energy pyramids for twodifferent ecosystems: a deciduous forest and aboreal forest

Procedure

1. Copy Table 1.3 into your notebook and write30 000 for Producers under the “EnergyPresent” column. This table will be for thedeciduous forest.

2. Remember that only 10 percent of the energy inproducers is available to the primary consumersthat eat the producers. Calculate the amount ofenergy available to the primary consumers.Record the value in your table.

3. Calculate the amount of energy available to thesecondary consumers and tertiary consumers,and record the values in the table.

4. To create the energy pyramid, you will need touse a scale for your model so that 10 mm equals2000 kJ/m2. Calculate the length, in millimetres,of paper strips you will need to represent eachlevel of the pyramid. Record the values in yourtable.

5. Cut a strip of paper to the correct length for theproducer level of the pyramid.

6. Repeat step 5 for the remaining levels of thepyramid. If you could not cut a narrow enoughstrip, use a pencil to draw a 2-cm vertical lineand indicate the width, in millimetres, that theline represents.

7. Glue the strips horizontally one above the otherto form a pyramid. Make sure that the producerstrip forms the base of the pyramid and that thetertiary consumer strip forms the top.

8. Label each level of the pyramid. Give thepyramid a title.

9. Repeat steps 1 to 6 for the boreal forest. (Forstep 1, write 12 000 for Producers under the“Energy Present” column.)

10. Glue the strips onto the same page below thedeciduous forest pyramid.

11. Label each level of the second pyramid, and givethe second pyramid a title.

Questions

12. Compared to the height of each pyramid, are thebases relatively large or small? What does thismean about the way energy flows through theecosystem?

13. Which forest has more energy available to theprimary consumers? More energy available tothe tertiary consumers?

14. Explain what happens to the energy that is nottransferred at each level of the pyramid.

15. Write a statement comparing energy availabilityin boreal and deciduous forests.

16. Suppose half of the deciduous forest was cutdown and not replanted. Explain theconsequences to the consumers in theecosystem. Would the consequences be thesame if half of the boreal forest was cut down?

Comparing Energy Pyramids

Materials & Equipment• calculator

• eight 2-cm strips of coloured paper

• ruler

EnergyPresent(kJ/m2)

Length ofPaper Strip(mm)

Producers 30 000

Primary consumers

Secondary consumers

Tertiary consumers

• glue

• scissors

• blank sheet ofpaper

Table 1.3 Energy Pyramid Data

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Key Concept Review1. What role do producers, consumers, and

decomposers each have in ecosystems?

2. Write the equation that summarizesphotosynthesis.

3. Look at the organisms pictured below.

(a) Identify the producer, primaryconsumer, and secondary consumer.

(b) Identify the decomposers in thisecosystem.

4. What are two processes that cause carbonto enter the atmosphere?

5. What are two processes that cause water toenter the atmosphere?

6. Give an example of how water moves fromthe biotic part to the abiotic part of anecosystem.

Connect Your Understanding7. When you eat a healthful meal, what two

things are you providing your body with?

8. How is an element different from anutrient?

9. All decomposers are consumers, but not allconsumers are decomposers. Explain.

10. Suppose that an unknown disease were tokill all the bacteria and fungi in anecosystem.

(a) Predict how this would affect nutrientcycling in the ecosystem.

(b) Predict what would happen to energyflow in the ecosystem.

11. How is the cycling of nutrients differentfrom the movement of energy in anecosystem?

12. Photosynthesis and cellular respiration arecalled “complementary processes.” Explainwhy.

13. A food web contains green plants,grasshoppers, frogs, snakes, insect-eatingbirds, and falcons.

(a) Identify the group that contains themost energy.

(b) Rank the remaining groups from mostto least in terms of energy content.

14. Suppose a plant could performphotosynthesis but it lost the ability toperform cellular respiration. Explain whatwould happen to the plant and why.

15. Consider a situation where a squirrel eats anut.

(a) How much of the energy in the nut willbe incorporated into the squirrel’stissues?

(b) Explain what happens to the remainingenergy.

Reflection16. In what ways has studying this section

changed your understanding of ecosystems?



Question 3

A B

C D

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Birth of an EcosystemOn November 14, 1963, an underwater volcano near Icelanderupted and poured lava onto the floor of the Atlantic Ocean,building the volcano ever closer to the ocean’s surface. Eventually,it rose above the surface and a new island was born. As Icelandwelcomed a new island into its territory, the world welcomed itsnewest ecosystem. The Icelandic government designated theisland, named Surtsey, as an ecological reserve (Figure 1.34).Only scientists visit to document the gradual appearance of newlife, seed by seed, plant by plant, bird by bird.

Many factors limit the populations of new species that can liveon Surtsey. Seeds can be blown to its shores by the wind, but theyfirst need soil to grow in. Although volcanic rock is rich in manyof the elements present in fertilizers, such as potassium,phosphorus, and sulphur, soil has other components, such asorganic matter. Birds often carry seeds in their stomachs. Whenthey land on the island, the birds can deposit viable seeds in theirwastes. Once they are deposited, the seeds are capable of growing.The birds’ wastes make excellent fertilizer. As small plants,lichens, mosses, and other organisms continue to grow, the firstsoils begin to form.


• Biotic interactions in acommunity include predation,competition, and symbiosis.

• Abiotic and biotic factorsprevent a population fromincreasing beyond its carryingcapacity.

Interactions in Ecosystems

Figure 1.34 The island of Surtsey near Iceland is less than 60 years old. It is a United NationsWorld Heritage Site.

1.3


Figure 1.35 Puffins started to neston Surtsey in 2002.

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A7 Quick Lab

Keeping a Balance

Organisms have to find resources in order to survive.

PurposeTo simulate the competition for resources over severalgenerations and see what happens to a population ofanimals

Procedure

1. You will be a member of one of two groups. Onegroup of five will represent the animal population,the other larger group will represent theresources. Record the number in each group.

2. The animal group forms a line down one side ofthe class. The resource group forms a line downthe other side. Each side faces away from theother.

3. Each person in both groups chooses a resourceand makes the appropriate hand sign (Table 1.4).(Do not turn around.)

4. On the signal from your teacher, turn around toface the other group. Each person in the animalgroup moves toward a person in the resourcegroup that has the same sign.

5. If an animal successfully finds a match, then theanimal escorts the resource back to his or herside and the resource becomes one of a newgeneration of animals. If an animal is unable tofind its resource, then it dies and becomes a partof the resource side.

6. Record the number of animals.

7. Repeat steps 2 to 6 another 10 to 15 more times.

8. Graph the data, and discuss the followingquestions with a partner.

Questions

9. What are some factors that affected the survivalof the animals?

10. Did you notice any trends?

11. Did the animal population rise, fall or stay thesame?

Materials & Equipment• graph paper

• paper and pencil

• ruler

Populations IncreaseAs years go by, the ability of Surtsey to support new species andlarger populations continues to increase (Figure 1.35).Populations will increase or decrease depending on theavailability of abiotic factors, such as water. Some factors havemore impact than others. For Surtsey, the main abiotic factor iswater erosion. Since the time it was formed, erosion has alreadyremoved half of the island. Erosion will eventually wash Surtseyback into the sea.

Resource Sign

Food Hand over stomach

Water Hand over mouth

ShelterHands over head to make a roof(elbows out and fingertips touching)

Table 1.4 Symbols

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Create a Picture Glossary

To learn unfamiliar terms,create a three-column chartin your notebook. Write thenew term in the first columnon the left. Add a definition inthe middle column. In thethird column, draw a picturethat will help you toremember the term.

During Reading Ecosystem InteractionsIn an ecosystem, many interactions are happening all the time. Forexample, producers use the Sun’s energy to produce carbohydrates,and while they are doing this they also take in nutrients and waterfrom the soil. Rising water levels on a lake can flood birds’ nests atthe water’s edge, preventing the eggs they contain from hatching.Predators hunt, catch, and eat their prey. This reduces the preypopulation, but this also makes the prey population healthier as awhole because predators often remove the least healthy preyindividuals from the ecosystem.

Aboriginal people describe these interactions as“connections.” These connections mean that when somethingchanges in an ecosystem, the change will affect other parts of theecosystem. For example, when a drought occurs, plants thatcannot survive in dry conditions die. Populations that depend onthose plants may have trouble surviving also.

Biotic InteractionsOrganisms in a community interact with one another in many ways.Three main ways are through competition, predation, and symbiosis.

CompetitionCompetition is the interaction between two or more organismscompeting for the same resource in a given habitat. Competitioncan occur between members of the same species. For example, malemountain goats compete to determine who will mate and produceoffspring. Members of different species may also compete forresources. For example, raccoons and ravens might both try to feedon eggs from the same nest of a common loon.


Cape May warbler

bay-breasted warbler

yellow-rumped warbler

Figure 1.36 These warbler speciesfeed on spruce budworms in differentparts of the same spruce tree. Noticethat there is some overlap of niches.

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For similar species to coexist in an area, they must haveslightly different niches. For example, many different species ofsimilar birds called warblers feed on the same spruce budworms,but each species feeds in a different part of the spruce tree (Figure1.36). This reduces the competition between them.

PredationPredation occurs when one organism eats another organism toobtain food. Prey animals are well adapted to avoid being eaten.For example, a deer can usually outrun a bear. A porcupine’squills are a formidable defence against lynx and other predators.Many animals use camouflage to avoid predators. For example, astick insect resembles the twigs that it lives on. By blending intoits surroundings, it avoids being eaten.

Other prey animals, such as the monarch butterfly, defendthemselves by tasting repulsive. They often have bright coloursto warn predators away. Some species use mimicry to avoidpredators. In mimicry, one species looks like another species.For example, the viceroy butterfly has markings similar to themonarch butterfly (Figure 1.37). Both species taste foul to theirpredators. By looking similar to each other, they both have agreater chance of not being eaten because their predatorsrecognize their markings and avoid them both.

Many predators have sharp eyesight, a keen sense of smell, orboth. An owl can spot a tiny mouse in the dark from high above andthen swoop down to grab it on wings that are adapted to make nosound. (Flapping sounds might scare the mouse away.) The owl’ssharp beak and claws are also adapted to snag and kill its prey.

SymbiosisSymbiosis is a close interaction between two different species inwhich members of one species live in, on, or near members ofanother species. There are three main types of symbiosis:


Figure 1.37 (a) The viceroy butterfly looks so similar to the (b) monarch butterfly thatpredators cannot tell them apart.

(a) (b)

WORDS MATTER

“Symbiosis” is derived from theGreek words syn, meaning with ortogether, and bios, meaning life.

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Figure 1.38 A leaf-cutter ant brings apiece of leaf into the colony. The whiteareas are the mould.

• In mutualism, both species benefit from the symbioticpartnership. For example, there is a South American speciesof ant called a leaf-cutter ant that has a mutualisticrelationship with a certain species of fungus (Figure 1.38).The fungus grows in the ants’ underground colony. Theants provide the fungus with a constant supply of leaves,and the ants eat certain parts of the fungus.

• Commensalism occurs when one species benefits from arelationship with another species without any harm orbenefit to the other species. A bird building a nest on abranch of a tree, where the nest does not harm or help thetree, is an example of this.

• Parasitism occurs when one species benefits at the expenseof another species. Parasites live on or inside the hostspecies and obtain some or all of their nutrition from thehost. Ticks live on the bodies of mammals and feed on thehost’s blood (Figure 1.39).

Characteristics of PopulationsAs a population grows, each individual gets a smaller share of theresources in the area. When this happens, the organisms affectedbecome stressed. Some die, while others are not able to reproduce.After a while, there are fewer births and more deaths. Eventually,the number of births equals the number of deaths and thepopulation is in equilibrium. In other words, the number ofindividuals stays the same over time.

Figure 1.40 shows a rabbit population that was introducedinto a new habitat. Notice that after a while, the number ofrabbits does not change. The habitat has reached its carryingcapacity. Carrying capacity is the maximum number of


Figure 1.39 A tick burrows into theskin of its host. Only the tick’sabdomen is visible.

carrying capacity

Time

Num

ber o

f Rab

bits

Ecosystem’s Carrying Capacity for a Rabbit Population

Figure 1.40 Real-world data on arabbit population over a long periodshow that the population increasesquickly at first but then increasesmore slowly until an equilibrium isreached and the population is steady.The ecosystem’s carrying capacity forrabbits has been reached. At thispoint, the number of rabbit birthsequals the number of rabbit deaths.

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individuals that an ecosystem can support without reducing itsability to support future generations of the same species. If apopulation exceeds its carrying capacity for a long time, it usuallyharms its environment.

Factors that Affect Populations inEcosystemsVarious combinations of abiotic and biotic factors causepopulations to increase or decrease. For example, if there is anunlimited amount of food, water, and space, populations can growvery quickly. Without any limits, 10 breeding pairs of rabbitscould expand to 10 million breeding pairs in only 3 years. In ahealthy, properly functioning ecosystem, limiting factors preventoverpopulation from happening. A limiting factor is anenvironmental factor that prevents an increase in the number oforganisms in a population or prevents them from moving intonew habitats (Figure 1.41).

• Abiotic limiting factors include the amounts of sunlight,water, soil, and air, natural disturbances such as storms,fires, and droughts, and human disturbances such as logging.

• Biotic limiting factors include competition amongorganisms for resources, presence of predators, reliance onother organisms for survival, and the presence of disease-causing organisms.


Figure 1.41 Many different factorscan limit a population’s size.

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Find out more about the close link between the lynx andsnowshoe hare populations,including the role plants play inthe lynx–snowshoe hare populationcycle. Begin your research atScienceSource.

Take It Further Consider a population of snowshoe hares, which are prey forlynx. As the population of hares increases, the lynx can capturehares more easily. The lynx are well fed and can have moreoffspring (Figure 1.42). As a result, their population increases.This increase in the number of lynx causes the number of hares todecrease because they are being eaten by more lynx. As more haresare eaten, the lynx’s food supply gets smaller. Some lynx starve,and those that survive may be too malnourished to produceoffspring. So, the lynx population declines as well. Finally, withfewer lynx preying on them, the hare population begins to recoverand the cycle repeats. This cycling is shown in Figure 1.43.

For an ecosystem to be sustainable, none of the populations inthe community can exceed its carrying capacity by very much orfor very long. If all the populations remain at their carryingcapacity, the ecosystem can usually be maintained without beingweakened or losing its important biotic and abiotic factors. Thegoal of sustainability is to meet the needs of the presentgeneration of individuals without affecting the ability of futuregenerations to meet their needs.


Lynx

Pop

ulat

ion

(thou

sand

s)

Hare Population (thousands)

Snowshoe Hare and Lynx Population Cycles

0

40

80

120

160

0

3

6

9

12

1850 1880 1910 1940Year

snowshoe hares lynx

Figure 1.43 The rise and fall of the lynx and showshoe hare populations follows a 10-year cycle.

Suggested Activity •A10 Inquiry Activity on page 44

Learning Checkpoint

1. How does the idea of niches explain how similar species can coexist with aminimum of competition?

2. List and explain the three types of symbiosis.

3. Explain what is meant by the following terms.

(a) limiting factor

(b) carrying capacity

(c) equilibrium

Figure 1.42 The survival of these lynxkittens depends on the size of thehare population.

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A8

Spotlight on NatureInternet, television, and print media are powerfultechnologies advertisers use to sell a wide varietyof products. Many corporations use images oforganisms and ecosystems in their advertising orin their logos.

Collect three advertisements from mediasources that use images of organisms as theircompany’s brand or to sell a product.

1. For each advertisement, suggest a reason orreasons why the company chose theorganism it did.

2. Explain whether there is a relationshipbetween the values of the company and theorganism being used in its advertising. Doesit matter whether a relationship exists?

3. Does the company in any way support theseorganisms in their natural environment?Does it cause the organisms harm?

4. In your opinion, does a company that usesan organism to help sell its products haveany responsibility to that organism? Explainyour position.


A9 Just-in-Time Math

A graph’s scale is the sequence of numbers placed beside the gridpoints that subdivide the axis. Here are some pointers for choosing ascale, assuming the scale starts at zero.

• Make sure the data point with the largest value falls in the top half

of the grid and below the top of the grid.

• Choose useful increments. Good increments include

ones (0, 1, 2, 3, 4, . . . ), twos (0, 2, 4, 6, 8, . . . ),

fives (0, 5, 10, 15, . . . ), and tens (0, 10, 20, 30, . . . ).

For example, suppose there are 14 grid points available (includingzero) for your y-axis and the largest y value in the data set is 20. If youchoose increments of two, then the scale will be 0, 2, 4, 6, 8, and soon. The y value of 20 will be plotted on the eleventh point (counting thezero) grid point, which is more than halfway up the grid and less thanthe maximum value that could be plotted, which is 26.

1. Assume you are selecting a scale for the y-axis of a graph thatbegins at zero. For each of the following situations, what incrementshould you choose and what is the maximum value that could beplotted on your scale?

(a) There are 33 grid points available (including 0), and the largesty value in the data set is 300.

(b) There are 12 grid points available (including 0), and the largesty value in the data set is 52.

Choosing a Scale2. For each of the following population

data sets, choose scales for the x- and y-axis and plot the data.

(a)

(b)

(c)

Time(years) Rabbit Fox

0 10 2

10 40 6

20 300 80

30 300 100


0 10 2

2 50 4

4 100 40

6 190 100

8 10 2


0 2 0

1 10 5

2 10 4

3 15 5

4 10 4

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A10 Inquiry Activity

Lynx are members of the cat family that live bypreying on snowshoe hares (Figure 1.44). In thisactivity, you will simulate the predator-preyinteractions between these two animals using a modelin which a desk represents a forest and cardboardand paper squares represent the lynx and hares inthat forest.

Each lynx is represented by one medium-sizedcardboard square, and each snowshoe hare isrepresented by a smaller paper square. When threesmall paper squares are tossed onto the desk, itrepresents three snowshoe hares entering and livingin the forest. When a medium-sized cardboardsquare is tossed onto the desk, it represents a lynxentering the forest to hunt. If a medium-sizedcardboard square lands on or touches a small papersquare, it means the lynx has eaten the hare.

You will generate and graph population data anduse the graph to predict future populations of eachspecies.

QuestionWhat are the long-term trends in the lynx andsnowshoe hare populations in this model ecosystem?

Predation Simulation

Figure 1.44 Snowshoe hare and lynx populations are closelylinked.

• desk or other flatsurface, 60 cm � 60 cm

• masking tape

• 250 paper squares,3 cm � 3 cm

• 12 cardboard squares,10 cm � 10 cm

• graph paper

Materials & Equipment

Generation Hares atStart ofGeneration

Lynx at Start of Generation

Hares Eaten

Lynx Starved

Surviving Hares

SurvivingLynx

HaresBorn

LynxBorn

1 3 1

2

3

Table 1.5 Predation Simulation Data Table

SKILLS YOU WILL USE� Processing and synthesizing

data� Interpreting data to identify

patterns or relationships

Key ActivityDI

Skills Reference 4

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A10 Inquiry Activity (continued)

Procedure

1. Create a data table similar to Table 1.5.

2. Use masking tape to mark a 60-cm square on adesktop. This represents a forest.

3. To start the first generation, toss three papersquares (representing snowshoe hares) atrandom onto the forest.

4. Toss one cardboard square (representing onelynx) onto the forest. Make sure it does not slidewhen it lands.

5. Note whether the lynx square touches any of thesnowshoe hare squares.

• Any snowshoe hare in contact with the lynxhas been eaten. Count and remove the eatensnowshoe hares. Record the number of haresthat were eaten.

• If the lynx is touching fewer than three hares,it has starved. Count and remove any starvedlynx. Record that the lynx starved by putting a1 in the “Lynx Starved” column of your datatable.

6. Determine the number of snowshoe hares andlynx born in this first generation.

• Any snowshoe hare not in contact with thelynx has survived and reproduced. One newhare is born for each hare that survives. Tossin one new snowshoe hare square for eachsurviving hare. Count and record the numberof hares born.

• If the lynx is in contact with three or morehares, it has survived and reproduced. Onenew lynx is born for every three hares eatenby the lynx. Toss in one new lynx square forevery three hares eaten by the lynx. Countand record the number of lynx born.

• If the lynx did not survive in the firstgeneration, wait for three generations beforeadding another lynx. In those generations, justadd hares. Then add one new lynx that hasmoved in from a neighbouring forest.

7. For the beginning of generation 2, the number ofhares will equal the surviving hares plus the new

hares born. Enter this number in your data table.The number of lynx will equal the surviving lynxplus any new lynx born. Enter this number inyour data table.

8. Continue the simulation until you have completed15 generations. If the hares are ever wiped out,restart the population with three new hares.

Analyzing and Interpreting

9. Graph the data for the lynx and hare populations.Plot both the lynx and hare data on the samegraph to make comparisons easier. Label the y-axis “Number of Animals” and the x-axis“Generations.”

(a) Describe any pattern you notice in thepopulation of hares.

(b) Describe any pattern you notice in thepopulation of lynx.

(c) Explain any relationship that exists between thepopulations of lynx and hares in your model.

10. Why do changes in the population of lynx lagbehind the changes in the hare population?

11. Snowshoe hares eat twigs from willow trees. Whensnowshoe hare populations are high, overeating ofwillow twigs occurs. As the hare population beginsto decrease due to a lack of food, the population ofwillow twigs increases, but young replacement twigscontain a toxin and cannot be eaten for two to threeyears. This can delay hare populations fromrecovering as quickly. Using this information, createa second graph that represents how the populationsof the willow, hares, and lynx may all interact.

Skill Practice

12. Based on patterns in your graph, predict what willhappen to the hare and lynx populations over thenext 10 generations.

Forming Conclusions

13. State the relationship between the population ofhares and the population of lynx.

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Key Concept Review1. Describe three adaptations that different

prey species use to avoid being eaten.

2. Suppose that there is a forested park inwhich squirrels are reproducing veryquickly because there is so much foodavailable. In this situation, the populationwill grow until it reaches the carryingcapacity. What will define the carryingcapacity of the squirrel population?

Connect Your Understanding3. Classify the following interactions as

mutualism, commensalism, or parasitism.

(a) A yucca moth caterpillar feeds on theyucca plant and pollinates the yuccaplant.

(b) Lice feed harmlessly on the feathers ofbirds.

(c) A cowbird removes an egg from arobin’s nest and replaces it with one ofits own.

(d) An orchid plant grows on the branch ofa tree. The tree remains healthy.

4. Identify the following limiting factors aseither abiotic or biotic.

(a) Wind blows the seeds of a dandelioninto a pond. The seeds fail to grow.

(b) A population of grasshoppers eats allthe available food, and their numbersdrop dramatically.

(c) A bacterium causes a deadly disease in aherd of reindeer, and some of them die.

(d) Plants growing beneath the trees in aforest are unable to get enough sunlight.

5. Does the success of a prey populationdepend on its predators? Explain.

6. Aphids are tiny insects that eat plants.What abiotic factors may contribute to thechanges in the population that you see inthe graph?

7. Cockroaches are insects that reproduce veryrapidly. Suggest reasons why the world isnot covered in cockroaches.

8. Revisit the interactions of the lynx and thehare. Predict how the predator-preyinteractions would change if a second preyspecies that ate the same food as the harewere introduced into the same area. Predicthow the cycle might change if a secondpredator were added. Draw a graph toillustrate your answers.

Reflection9. Limiting factors normally control a

population from expanding past itscarrying capacity in a specific area. Mostof the limiting factors that would normallycontrol the human population have beenremoved through various technologies.How does this affect your quality of life?How might it affect your children’s orgrandchildren’s lives?


Num

ber o

f Aph

ids

April May Jun Jul AugMonth

Aphid Population

Sep Oct Nov Dec

Question 6

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47Ecosystems are complex self-regulating systems of organisms and their abiotic environments.

This bird is looking for parasites. The birdgets a tasty meal, and the buffalo gets ridof itchy pests such as ticks. However,these birds can also be parasites. If abuffalo is wounded, the birds will pick atthe scabs, which keeps the wound openand prevents it from healing.

The clownfish and the sea anemone are each other’sguardians. The clownfish can swim safely among theanemone’s stinging tentacles. This ability protects theclownfish because its predators will not get close tothe stinging tentacles. There are several species offish that can tolerate the anemone's stings and willeat the anemone's tentacles, if given a chance. Thisis where the clownfish comes in. It will chase awayany fish that comes too close to the anemone, and soprotects the anemone.

The adult monarch butterfly feeds on the nectar in the flowersof the milkweed plant and pollinates it. The butterfly also lays its eggs on the plant. When the eggs hatch, the larvae andcaterpillars feed on the plant. Milkweed sap contains a largeamount of a substance called latex. The monarch larvae andcaterpillars incorporate this substance into their tissues. As aresult, they taste bad and are poisonous. Monarch butterfliesfeed exclusively on milkweed plants.

SCIENCEeverywhereeverywhere

Cool SymbiosisCool Symbiosis

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Key Concept Review

1. List the following terms in order fromsmallest to largest.

biome, ecosystem, biosphere, habitat

2. Identify the following items in thephotograph.

(a) a species

(b) a population

(c) a community

(d) an ecosystem

3. (a) Describe the role photosynthesis playsin the carbon cycle.

(b) Describe the role that cellularrespiration plays in the carbon cycle.

4. What term best describes where all life isfound?

5. Name four elements that are found in mostorganisms.

6. Give an example of an abiotic reservoir.

7. (a) What do nitrifying bacteria do?

(b) What do denitrifying bacteria do?

8. What is the difference between a habitatand a niche?

9. When similar species live in the samehabitat, explain how competition betweenthese species is reduced.

10. Name the five main terrestrial biomesfound in Canada.

11. The open ocean and a lake are both aquaticbiomes. What abiotic factor makes the twobiomes different?

Connect Your Understanding

12. Predict what would happen if a plant froma deciduous forest were transplanted to thetundra. Explain your answer.

13. Compare a forest to a bicycle. How are theysimilar, and how are they different?

14. The black-throated blue warbler migratesfrom the Caribbean to wetlands innorthern Ontario each spring, and then itflies back again in the fall. Why would thebird make such a lengthy journey twotimes a year?

15. A crow’s niche is being a scavenger. Is thisan accurate description of its niche? Justifyyour answer.

16. Pick any organism in your area and explainhow it has adapted to the specific biotic andabiotic factors of that environment.

17. Photosynthesis is the most importantprocess on Earth. Justify this statement. a

a

t

t

t

t

k

k

k

k

k

k

k

k

k

k

k

k

k

k

k

ACHIEVEMENT CHART CATEGORIES

Knowledge and understanding Thinking and investigation

Communication Applicationac

tk

1 CHAPTER REVIEW

Question 2

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18. The paths that nutrients and energy takein ecosystems are different.

(a) Draw a symbol to indicate the pathenergy takes.

(b) Draw a symbol to indicate the pathnutrients take.

19. Suppose that a herd of reindeer had beenintroduced to a small island that had noreindeer on it and their population hadbeen monitored. The table below shows thepopulation data.

(a) Graph the population data.

(b) Suggest why the population of reindeerwas lower in 1940 than in 1935.

(c) Extend the graph, predicting thepopulation in 1950 and 1960 byextrapolating from the given data.Several different plausibleextrapolations are possible. Suggest oneor more, and be prepared to explainyour predictions.

20. When a predator catches its prey, it mayappear that the prey species suffers. Butthere are benefits to this type of interactionfor the prey species as well. What are twoways in which the prey species may benefitfrom the predator hunting them?

21. Bacteria can reproduce so quickly that,under ideal conditions, one bacterium couldproduce enough bacteria to cover the entireplanet in only a few weeks. Explain whythis does not happen.

22. Suppose you had to create an imaginaryanimal and its predators are eagles. Whatadaptations would you give this animal toavoid being caught by an eagle?

23. Disease-causing organisms can be termedparasites. However, in this chapter, diseaseand parasites are both listed as bioticlimiting factors. Why do you suppose the author chose to separate these twofactors?

Reflection24. Describe three things you did not know

about ecosystems before you startedworking on this chapter.

25. You have learned about competition amongspecies. Think of your daily activities, andlist some ways you may compete with otherspecies for resources. c

c

a

a

a

a

t

t

t

c

c

Reflect and Evaluate

How did the use of visualization and picturemapping help you to understand new ideas andterms? Share with a partner one of the diagramsor picture maps that you drew, and explain theconcept or terms that it illustrates.

After Reading

Unit Task Link

In the Unit Task, you will be designing acommunity that will have as low an impact aspossible on the surrounding ecosystems. You willhave to assess the abiotic and biotic factors inyour area. What are the abiotic factors that affectthe area where you live (for example, availability ofwater, average temperatures, and amount ofsunlight)? Also think about the energy flow andcycling of matter. Where does your energy comefrom? How is matter cycled where you live?

Year Population

1910 50

1920 250

1930 500

1935 2000

1940 1400

Reindeer Population 1910–1940

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2 Human activity affects the sustainabilityof ecosystems.

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Human activity affects the sustainability of ecosystems. 51

A pulp and paper mill produces paper, but it alsoproduces pollution.

Skills You Will UseIn this chapter, you will:

• plan and carry out investigations into how using fertilizeraffects water quality and the fertility of soil and explain howfertilizer use affects the survival of a terrestrial and anaquatic ecosystem

• interpret data from undisturbed and disturbed ecosystems,communicate the results graphically, extrapolate from thedata, and infer the importance of biodiversity forsustainable ecosystems

• analyze the effect of human activity on populations inecosystems by interpreting data and generating graphs


• identify human activities that can upset the balance ofecosystems and affect their survival

Why It Is ImportantHumans need ecosystems. Human activities have harmedecosystems in many ways. If we know what factors lead to adecrease in biodiversity in ecosystems, we can take steps toundo or lessen the damage we have done to them. We alsoneed tools to assess the damage that we have done toecosystems. If we know what causes soil and water quality tobe reduced, we can take steps to fix the damage or preventfurther damage to ecosystems.

Asking Questions of the Text and ofOurselves

Good readers do not read passively. They think as theyread and evaluate the information, often asking questionsabout the different ideas in the text. They also questiontheir own and others’ actions and decisions that mayhave contributed to a particular situation. Skim thesubheadings in chapter 2, and turn them into questionsthat begin with “How can we...?” or “How do we...?”

Key Terms

• acid rain • bioaccumulation • biological oxygen demand• biomagnification • clearcutting • eutrophication • habitat change • heavy metals • invasive species • overexploitation • pesticide • urban sprawl

Before Reading

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A Lesson in SustainabilityIn 1722, Dutch sailors arrived on Easter Island, a 165-km2 island inthe Pacific Ocean. They found an island with no trees and littlesignificant plant life. There were also no domestic animals. The fewpeople on the island were so desperate for food that they had resortedto cannibalism. The mystery of what happened on the island hasonly recently been solved after scientists discovered that EasterIsland had once been covered with large palm trees.

Hundreds of years ago, a small group of Polynesians migratedfrom a nearby island to Easter Island in large sea-going canoes.They brought chickens, rats, dogs, and some crop plants withthem. When they arrived, the island was covered with palm trees.The island’s climate proved to be too cool to grow their crops, butits coasts were rich with sea life: porpoises, fish, turtles, andnesting birds. Within five or six centuries, the population grew to10 000. With more people, they needed more resources. Theyhunted all the animals that were close to shore, and they had toventure farther out to sea to find food. They also cut down thepalm trees to use for fuel faster than the trees could grow back.To complicate matters, the rats they brought with them ate boththe seeds and saplings of young trees.



• All human societies depend onsustainable ecosystemscharacterized by maximumbiodiversity.

• Managing the world’secosystems means achievingsustainable use, preventingsudden irreversible changes toecosystems, and addressingthe impact of poverty onsociety and sustainability.

• Habitat change,overexploitation, pollution,invasive species, and climatechange are the main factorsinfluencing loss of biodiversity.

Human Use of Ecosystems

Figure 2.1 These stone statues are roughly 4 m high, and each has a mass of over 11 tonnes.No one knows exactly how the Easter Islanders moved these statues from the quarries acrossthe island to the coast, where they currently sit.

2.1

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Eventually, the last tree was cut down. Due tothe lack of wood, the islanders no longer hadworking canoes, and food became very scarce. Theislanders ate all the dogs, rats, chickens, and nearlyall the nesting birds. By the time the Europeansarrived, there were only a few small communitiesliving in caves. The islanders’ only legacy was theirstone statues (Figure 2.1).

Because of unrestricted population growth, toohigh a demand on their resources, and no long-termplan to use their resources wisely, the result was anecological disaster, which caused the population tocrash. Easter Island shows what can happen whenresources are not used in a sustainable way.

53Human activity affects the sustainability of ecosystems.

A11 Quick Lab

Managing Resources

PurposeTo manage a resource, candy, in a sustainable way

Procedure

1. In small groups, arrange yourselves so that youare facing each other with 16 candies in a pile ona paper napkin in the middle of your group. Eachgroup member plays once per round. Work out agroup agreement on the order of play.

2. The candies represent your resources. Your goalis to manage them as you see fit, either asindividuals or as a group.

3. Each turn, a player will have an opportunity toremove candies from the pile. (Do not eat any ofthe candies.)

• To survive, each group member must take atleast one candy per turn.

• During his or her turn, each group membermay take as many candies from the resourcepile as he or she wishes.

4. After each round, count the number of candiesleft in the resource pile and add the same numberof candies to the pile. For example, if there are10 candies left in the pile, add 10 more to thepile.

5. Stop after three rounds. Assess what hashappened as a result of the game play so far.

6. Restart the simulation several times, trying outdifferent strategies for managing the candies.Note the results.

Questions

7. Decide on a set of rules that would result in thebest sustainability for the group with the leastamount of restrictions on the behaviour ofindividuals.

8. In what situations would a one-time renewal ofcandy resources lead to sustainable availability ofcandies in the long term?

Materials & Equipment• 100 small candies

• 1 paper napkin or piece of paper towel

Figure 2.2 Modern-day Easter Island

CAUTION: Do not eat anything in the lab.

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Human Impacts and BiodiversityHuman well-being depends upon ecosystems. Ecosystems providehumans with many services. Ecosystems supply food, fuel,natural resources, and water. Ecosystems cycle nutrients anddecompose wastes. They regulate climate. The animals theycontain help pollinate crops and disperse seeds. Ecosystems alsoprovide humans with cultural and recreational opportunities(Figure 2.3).

All the species contained in ecosystems contribute to theseservices. So we all have a vital interest in maintaining biodiversity,which is the types and numbers of organisms in an ecosystem. Tomaintain biodiversity, we have to use ecosystems in a sustainableway. Sustainable use of an ecosystem means using an ecosystem’sresources in a way that meets our current needs withoutcompromising the ability of future generations to meet their needs.

So far, we have referred to biodiversity as the variety ofspecies on Earth. But the term also refers to other levels ofbiodiversity. There is diversity within a species. For example,members of a human family may all look similar, yet eachindividual is unique and is different from every other member.Differences in individuals can help keep a population healthy. Forexample, in a wolf pack some wolves may be better able to resistcertain diseases than other members, and some may be betterthan others at tolerating a lack of water (Figure 2.4). Thesedifferences among individuals of the same species are calledgenetic differences or genetic diversity. Lack of genetic diversityin a population can be a real threat to its survival and can evenlead to extinction. Extinction is the death of every member of aspecies. Reducing the sizes of populations can reduce geneticdiversity in a population, putting the whole population at risk.


Figure 2.3 Enjoying nature contributes to the well-being of humans.

Figure 2.4 These wolf pups maylook similar, but each one has slightdifferences that may influence itssurvival.

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During Reading

Making Inferences

By asking the question “Why?”you can often make inferencesor calculated guesses about thefactors that affect biodiversity.As you read about each factor,ask the question “Why?” andmake note of your answers.Draw conclusions about how wemight lessen the effect of these factors.

Biodiversity also refers to the variety of ecosystems found onEarth. This includes human-made ecosystems, such as farms, aswell as the variety of naturally occurring ecosystems. Becausedifferent ecosystems provide different services, it is vital that wemaintain as many types of ecosystems as possible.

Human activity has caused all levels of biodiversity to decreaseat an unprecedented rate. The five major causes of this are:

• habitat change

• overexploitation

• pollution

• invasive species

• climate change

Habitat ChangeHabitat change is the process by which humans alter a habitatenough so that the native species can no longer live there. Nativespecies are species that normally live in that habitat. If theirhabitat changes, they either die or move to another habitat.Throughout the biosphere, habitat change is the most commoncause of declines in the populations of many species.

Humans change habitats for many different purposes. Weclear land for things such as agriculture, forestry, and urbandevelopment (Figure 2.5). Habitat change has been severe in theworld’s tropical rainforests. Currently, only 9 million squarekilometres are left of the 16 million square kilometres thatoriginally existed.


Figure 2.5 This tropical rainforest in Brazil is being cleared in order to create pasture forcattle.

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Altering habitat may also lead to habitat fragmentation.Often, small areas within a large region are altered a bit at a time.This creates a patchwork of altered and original habitats. Forexample, southern Ontario was once covered in deciduous forest.Now, the original forest habitat is fragmented into small patchesof forest interspersed among farms, suburban developments, andcities.

Habitat change also occurs in marine and coastal systems. Forexample, in a fishing method called bottom trawling, nets aredragged along the bottom of the oceans to catch shrimp andbottom-dwelling fish. This can completely disrupt the marineecosystem by removing many producers from the food web aswell as harming coral formations (Figure 2.6).

OverexploitationOverexploitation of a resource means using a resource fasterthan it can be replaced. Overexploitation can often lead toextinction. A common example of overexploitation is overfishing.Around the world, many species of fish have been overfished,which has resulted in complete collapse of these populations offish. Since the 1950s, humans have removed an estimated90 percent of large fish from the sea. Overexploitation of the seasis one of the greatest environmental catastrophes in humanhistory.

One example of overexploitation of a fish stock occurred inAtlantic Canada, where cod used to be abundant (Figure 2.7). Overthe past century, the demand for cod grew and fishing technologiesallowed more cod to be caught. Mature fish normally swimrelatively close to the surface. When fishing fleets no longer caught


Figure 2.6 (a) A redfish in an intact ocean reef (b) After a bottom trawler has passed, a reef has been reduced to rubble.

Figure 2.7 Catching cod in the1940s

(a) (b)

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fish at the surface, they fished deeper in the ocean, where theyoung fish are found. The fish on which cod fed were also locatedfarther down. By fishing deeper, the industry was, in effect,collecting next year’s cod harvest as well as the cod’s food source.By the 1990s, the populations were so low that the cod fishery hadto be closed. The cod populations have yet to recover (Figure 2.8).

Overuse of WaterAround the world, fresh water is a precious resource. Canada hasthe world’s largest supply of fresh water, and we are still workingon ways to sustainably manage it. The consequences of watermismanagement are illustrated by the Aral Sea in central Asia(Figure 2.9).

The Aral Sea was once the fourth-largest lake in the world. Itis called a sea because it is so large, but it is a freshwaterecosystem. The government of what was then the Soviet Uniondecided to grow cotton and rice in the region. To irrigate thecrops, water was diverted from the two rivers that flowedinto the lake. Slowly, the lake’s water level dropped(Figure 2.10 on the following page). Dropping water levelssplit the lake in two, creating the North Aral Sea and theSouth Aral Sea. The water drop affected the ecosystem inthe lake, including the fish. Many people relied on fishingfor jobs. But as the water level dropped, the fishdisappeared. As a result, the lake’s commercial fishery nolonger exists. Despite the slow shrinkage of the sea, therivers are still being diverted for irrigation. However, theKazakh government has increased water flow into thelake, and the North Aral Sea level is slowly rising.


Fish

Cat

ches

(ton

s)

0

100 000

200 000

300 000

400 000

600 000

700 000

800 000

900 000

500 000

1850 1860 1870 1880 1890Year

1900 1910 1920 1930 1940 1950 1960 1970 1980 1990 2000

Source: Millennium Ecosystem Assessment

Figure 2.8 Cod were fishedcommercially for 500 years beforethe modern industrial fishing fleetswiped out much of the population.

Suggested STSE Activity •A12 Decision-Making Analysis on page 64

Canadian Cod Harvest 1850–2002

RUSSIA

TURKEY

UKRAINE

ARMENIA

AZERBAIJAN

GEORGIA

SYRIA

IRAQ IRAN AFGHANISTAN

KAZAKHSTAN

TURKMENISTAN

UZBEKISTAN

CYPRUS

JORDANISRAELLEBANON

ROMANIA

BULGARIA

MOLDOVA

BELARUS

Black Sea

Caspian Sea

Aral Sea

0 400 800 km

N

Figure 2.9 The Aral Sea borders Kazakhstan andUzbekistan.

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PollutionPollution is any substance added to the environment thatproduces a condition that is harmful to organisms. One exampleof pollution is solid waste that cannot be recycled. The garbageyou put out on the curb or take to the landfill is solid waste.Currently, most garbage goes to landfills, where it is preventedfrom entering the environment. Garbage that does not enter thelandfill and litter contaminate ecosystems.

Another form of pollution is air pollution. One of the mostimportant pollutants worldwide is human-produced carbondioxide gas. Automobiles, airplanes, power plants, and factoriesall emit carbon dioxide. Increased levels of carbon dioxide havecaused global temperatures to rise. This, in turn, is acceleratingglobal climate change.

Water can become polluted very easily. Pollution can enterwater sources in different ways (Figure 2.11). Point sourcepollution enters a body of water at a specific place from anidentifiable source. Oil spills from tankers, waste water from pulpand paper mills, and partly treated waste water released from asewage treatment plant are examples of point-source pollution.Non-point source pollution enters bodies of water indirectlywhen water from rain or snow travels over land and picks uppollutants from many different sources before entering a streamor a lake. Fertilizer and pesticide run-off from farms and salt run-off from roads are both examples of non-point source pollution.Since all organisms need water, all organisms are exposed to thepollutants water contains. You will learn more about waterpollution in the following section.


Figure 2.10 (a) The Aral Sea was already shrinking in 1985. (b) By 2007, it was less than10 percent of its original size.

(a) (b)

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Invasive SpeciesIncreases in international travel and trade have introducednon-native species to all parts of the globe. For example, the GreatLakes are part of an important shipping route. While in thesewaters, foreign ships may release non-native species when theyempty their ballast tanks. An invasive species is a non-nativespecies that causes harm to the ecosystem into which it has beenintroduced. Invasive species tend to outcompete native species,often because they have no natural predators in the newecosystem or they reproduce faster than native species. As aresult, their populations increase rapidly while native species’populations decline (Figure 2.12). The dog-strangling vine isnative to Eurasia and was introduced to North America as agarden plant (Figure 2.13). It has invaded sunny hillsides andravines across southern Ontario. It grows in dense colonies andsmothers small plants and tree seedlings, small shrubs, andsaplings. It also affects monarch butterflies. The vine is a memberof the milkweed family. Monarchs lay their eggs on nativemilkweed plants, but they will also lay them on the dog-stranglingvine. However, the larvae cannot survive on the vine and die.


Figure 2.12 The eastern bluebirdhas suffered from the presence ofstarlings and sparrows. These twoinvasive species outcompetebluebirds for nest sites. In the pastcentury, bluebird populationsdeclined by 90 percent.

industrialpoint source

forestnon-point sources

urbannon-point sources

agricultural non-point sources

septic systems

Figure 2.11 Point and non-pointsources of pollution

Suggested STSE Activity •A13 Decision-Making Analysis Case Study on page 66

Figure 2.13 The dog-strangling vinehas completely invaded theunderstorey of this tree plantation.

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Climate ChangeClimate change is a cause of loss of biodiversity around theworld. Climate is the average weather conditions that occur in aregion over a span of 30 years or more. When climate changeoccurs in a region, average temperatures may rise or fall, theamount of rainfall may increase or decrease, and even generalwind directions may change. If species are to survive throughperiods of climate change, individuals must be able to adapt to

the new conditions. However, climate change iscurrently being driven by a process called globalwarming, which is an increase in Earth’s averagetemperature, caused partly by an increase incarbon dioxide in the atmosphere. Over the pasttwo centuries, the amount of carbon dioxide inthe atmosphere has increased, largely due tohuman activities that burn fossil fuels. Globalwarming has caused relatively rapid climatechange. For example, the Arctic is warming fasterthan at any time in recorded history. The icepacks are shrinking and breaking up. Species thatdepend on ice packs, such as seals and polarbears, are losing their habitat (Figure 2.14). As aresult, their populations are declining.

Human Impacts on Ontario EcosystemsPeople in Ontario use the land and water for a variety of differentpurposes: farming, housing, industry, recreation, mining, logging,and a whole host of other uses. Each human activity affects theland and local biodiversity in different ways. By knowing how ahuman activity affects the ecosystem, steps can be taken to helplessen these effects.


Learning Checkpoint

1. List three levels of biodiversity.

2. What is the difference between habitat change and habitat fragmentation?

3. What resources have been overexploited?

4. (a) Name an invasive species in Ontario.

(b) Explain how this species has affected native species.

Frigure 2.14 Walruses in the eastern Arctic rely on ice floes.They haul themselves onto the ice to rest.

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A Freshwater EcosystemThe thriving cottage and recreational industries in Ontario put agreat deal of stress on the lake ecosystems. Figure 2.15 showssome of the sources of stress on a typical lake in cottage country.Table 2.1 summarizes the effects of these stresses.

These stresses affect the sustainability and biodiversity of afreshwater ecosystem. For example, some animals, such as loons,are affected by waves from boat wakes. They will move to otherless disturbed habitat. The fish populations decline due to thepollution.


Stress Effects

Motor boats Oil leaks can easily contaminate lake water.Oil reduces the water’s oxygen level and so affects the healthof fish and other lake organisms.

Sewage Sewage leaking from septic tanks can increase the nitrogencontent of the water. This contamination eventually reducesthe biodiversity of aquatic organisms.

Docks Building docks can disturb fish spawning grounds anddisturbs floating and submerged aquatic vegetation.

Boat wakes Waves disturb aquatic and terrestrial vegetation along theshoreline and nesting sites of loons and other birds.

Beaches Removal of aquatic and terrestrial vegetation along theshoreline means loss of habitat for other organisms.

Clearing shoreline When shoreline vegetation is cut down, fish lose the shadeand cover the vegetation provides.

Table 2.1 Stresses on Lakes and Their Effects

Figure 2.15 A typical lake in the heart of Ontario’s cottage country

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A Suburban Terrestrial EcosystemThe Niagara Escarpment is a long cliff that forms theboundary between two flat regions, each with adifferent elevation. The escarpment stretches 725 kmfrom the western end of Lake Erie, northwest to thetip of the Bruce Peninsula (Figure 2.16). Mostfamously, it forms the ledge that makes Niagara Fallsso impressive. Along its length are forests and otherwildlife habitats, and the headwaters for five majorrivers flow from its slopes (Figure 2.17). Among itsforests are cedar trees that are over 1000 years old.

The Niagara Escarpment also runs through theGolden Horseshoe, one of the most heavily populatedareas in Canada. Cities such as Hamilton are built onthe edge of the escarpment. As the population ofsouthern Ontario grew, so did the demand for landfor housing developments, industry, farmland,vineyards, and rock quarries. Some parts of theescarpment gradually fell victim to urban sprawl.Urban sprawl is the unplanned, disorganizedgrowth of urban and suburban development into thesurrounding countryside. Urban sprawl has affectedlocal biodiversity through habitat change and habitat

fragmentation. The remaining undisturbed forest on theescarpment is now in smaller, disconnected sections. A smaller,fragmented habitat leads to a loss of biodiversity.

The Ontario government recognized that the escarpment’secosystems were threatened, so it created the Niagara EscarpmentPlan. It is a land-use plan that focusses on environmentalprotection. It has guidelines on how land in the escarpment areacan be developed.

A Forest EcosystemBoreal forest covers most of Ontario’s land area. Commerciallogging is a major industry in northern Ontario. Loggingcompanies often use clearcutting to remove trees. Clearcuttingremoves all the trees in an area at one time, regardless of size.When forestry companies clear-cut forests, they break large areasof forest into smaller fragments (Figure 2.18), which can threatenlocal biodiversity. Some species, such as wolves, require very largeareas of forest to hunt moose and other prey. Fragmenting theirhabitat makes it difficult to find food.


Orangeville

Niagara Falls

Toronto

Georgian Bay

OwenSound

N

PEEL

HALTON

NIAGARA

WELLAND

GREYCOUNTY

SIMCOECOUNTY

BRUCECOUNTY

DUFFERINCOUNTY

HAMILTONWENTWORTH Hamilton

LakeOntario

LakeHuron

Barrie

Niagara Escarpment Plan area0 25 50 km Lake

Erie

BrucePeninsula

Figure 2.16 The escarpment area marked on the mapcontains natural areas, farmland, subdivisions, andparks.

Figure 2.17 Bruce Peninsula NationalPark is one of the protected areas onthe Niagara Escarpment.

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Overexploitation of water happens in North America. Findout about the state of the OgallalaAquifer. Begin your research atScienceSource.

Take It Further

Fragmentation is a serious problem in Ontario. About30 percent of northern Ontario’s boreal forests are within threekilometres of a road. This increases animal deaths through roadkill, habitat destruction, altered water flow, and soildegradation.

Ontario has adopted certain measures to ensure a sustainableforestry industry. Companies have to plant new trees in an areathat has been clear-cut. Also, they are not allowed to cut downmore trees than they can replant in the same year. Loggingcompanies have started to use more sustainable logging practices,such as leaving the forest in place around bodies of water. Thisreduces changes in water flow that can result from logging.


Figure 2.18 Logging companies clear-cut relatively small sections of forest, leaving otherpatches still standing.

Learning Checkpoint

1. (a) What are three stresses put on a freshwater lake in Ontario?

(b) Describe the effects of these stresses.

2. Explain how urban sprawl affects the Niagara Escarpment.

3. What is clearcutting?

4. What is the major effect that clearcutting has on the boreal forestecosystem?

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A12 Decision-Making Analysis

IssueFish stocks around the globe have been drasticallyreduced due to unsustainable fishing practices. Manycountries are turning to fish farms, also known asaquaculture, in which the fish are housed inunderwater cages and farmed. However, some kindsof fish farming are very controversial becausediseases among farmed fish sometimes infect wildstocks. Also, farmed fish that escape can becomeinvasive species or interbreed with wild stocks,potentially weakening the wild stocks.

Fishing wild species almost always results inby-catch, which is unintentionally catching fishspecies other than the target fish species. Sometimes,the fish populations most threatened by fishing wildstocks are not even the intended catch. This leaves avery important question: which is more sustainable,aquaculture, wild stock fishing, or a mixture of both?

Background InformationMaking management decisions about fishingdepends on knowledge of wild fish populations. If wildstocks are threatened by overexploitation, banningfishing is a sound decision. However, how do weknow if a fish population is threatened?

Gathering data on fish and other species frommarine and freshwater ecosystems is challenging.One method is to keep track of the total mass, ortonnage, of fish caught in commercial fisheries.However, relying solely on this data has often meantthat by the time enough data were gathered andanalyzed, the fish population was already in anadvanced stage of collapse. Around the world, stocksof many different species have collapsed. This hashappened time and time again across the globe in thelast half century, mainly due to the introduction oflarge factory fishing fleets.

Even so, a great deal of valuable information canbe inferred from the data obtained through fisheries.

Data from harvests of three species of wild stocks arepresented in Table 2.2. These numbers are actualdata taken from Fisheries and Oceans StatisticalServices archives. The numbers represent the totalmass of fish caught in Canada. Table 2.3 on the nextpage shows data on farmed salmon and trout.

Wild Fish Versus Farmed Fish

SKILLS YOU WILL USE� Defining and clarifying the

research problem� Justifying conclusions

Year Cod Redfish Herring

2006 28 266 32 525 182 194

2005 27 693 34 273 192 041

2004 26 049 32 431 207 235

2003 23 573 36 268 229 613

2002 36 434 36 898 219 648

2001 40 913 41 583 224 914

2000 46 888 44 306 233 785

1999 56 314 43 683 214 679

1998 39 201 47 691 216 836

1997 31 418 39 277 218 525

1996 16 447 45 200 211 568

1995 14 661 39 624 220 472

1994 26 270 75 070 247 777

1993 84 767 109 329 242 968

1992 198 078 125 103 251 433

1991 321 833 116 109 256 485

1990 401 257 109 164 301 328

1989 435 373 100 604 270 035

1988 479 141 104 828 310 283

1987 471 897 104 774 284 626

1986 478 730 104 320 203 086

1985 492 767 89 283 219 167

Table 2.2 Wild Fish Harvests 1985–2006 (tonnes)

STSE Skills References 4, 9

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A12 Decision-Making Analysis (continued)

Analyze and Evaluate

1. Create a line graph for each wild species listed inTable 2.2. Graph the data for all three species onone graph. Choose the vertical scale (tonnes offish harvested) carefully so that all the data fit onthe graph. Use a different coloured pencil foreach species. Be sure to put a legend and title onyour graph.

2. Create a second line graph for the farmedspecies in Table 2.3. The vertical scale willprobably be different than the one on the firstgraph because the numbers are much smaller.Use a different coloured pencil for each species,and add a legend and a title.

3. Describe any trends you see in the wild fish data.

4. Some wild fish populations change moredrastically than others. Suggest reasons for this.

5. What inferences can you draw aboutsustainability of the wild stocks over time?

6. Describe any trends you see in the farmed fishdata.

7. What do the data from the farmed fish stockssuggest about the sustainability of aquaculture?

8. Fish harvest data alone do not give enoughinformation to decide which kind of fishingmethod is more sustainable. Working in smallgroups, choose one of the two fishing methods toinvestigate. Research the pros and cons of yourchosen method. Consider the costs and benefitsto society and to the environment.

9. Summarize your findings, and present a brief listof the costs and benefits of your method to theclass.

10. As a class, discuss the issue and try to reach aconsensus as to the most sustainable way to usewild fish and farmed fish.

Skill Practice

11. Justify any conclusions you drew from thediscussion.

Table 2.3 Aquaculture Harvests 1986–2006 (tonnes)

STSE

Year Salmon Trout

2006 118 058 5 033

2005 98 369 4 878

2004 90 646 4 858

2003 99 961 5 253

2002 126 321 6 833

2001 105 606 6 513

2000 82 195 6 514

1999 72 890 6 574

1998 58 618 6 022

1997 57 775 5 930

1996 45 624 6 615

1995 42 515 4 429

1994 36 083 4 004

1993 36 670 3 718

1992 30 325 3 511

1991 34 109 2 839

1990 ? 4 497

1989 ? 3 614

1988 ? 3 259

1987 ? 2 842

1986 ? 2 167

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CASE STUDY

Decision-Making Analysis

IssueWhen people mention dangerous fish, sharks,piranhas, and barracudas probably come to mind.By comparison, the round goby seems harmless(Figure 2.19). However, this fish and other invasivespecies cost the Ontario economy hundreds ofmillions of dollars. How could human activities bemodified to minimize or prevent the introduction ofnon-native organisms to the environment?

Background InformationNative to eastern Europe, the round goby arrived inNorth America in the ballast tanks of a ship. Whenthe ship dumped its ballast water in Lake St. Clair, itreleased a number of invasive species into the GreatLakes, including the round goby.

The round goby arrived in North America withoutthe predators and parasites that are associated with itin its natural habitat, and the exotic invader was freeto reproduce as fast as it could. The round goby ishighly territorial and able to outcompete many nativefish, including mottled sculpin and native logperch,causing declines in these populations.

This fish is relatively small, growing to anaverage length of 18 cm in the Great Lakes. It prefersthe rocky and sandy lake bottoms that are typical ofthe Great Lakes. In addition to displacing a numberof native fish, the round goby is also a voraciouspredator of another invasive species, the zebra

mussel. Zebra mussels often have very high levels ofcontaminants in their tissues. These becomeconcentrated in the round goby. Any animals that eatthe round goby are likely to have much higher levelsof contaminants in their tissues as well.

Other invasive species, including the Eurasianruffe, spiny water flea, zebra mussel, and purpleloosestrife, have also been introduced to the GreatLakes through ballast water.


1. ScienceSource Use the Internet to research howhuman activities have contributed to theintroduction of so many invasive species in theGreat Lakes. Identify how the invasive speciesand native species interact. Also research howthe environment and human society have beenaffected by the invasive species.

2. Draw a concept map to show the social,economic, and environmental consequences ofthese interactions.

3. Analyze your research, and describe the effectsinvasive species have on society, the economy,and the environment.

4. Write a proposal to the Ministry of NaturalResources recommending which humanactivities should be discontinued in the GreatLakes to reduce the introduction of non-nativespecies. Alternatively, you may propose potentialsolutions to reduce the introduction of invasiveorganisms to the Great Lakes.

5. Web 2.0 Develop your proposal as a Wiki, apresentation, a video, or a podcast. For support,go to ScienceSource.

Skill Practice

6. Summarize the information you found in abrochure for the public to educate them aboutthe issue.

SKILLS YOU WILL USE� Gathering information� Summarizing information

Invasive Species

A13 Skills Reference 4

Figure 2.19 The round goby is a relatively small fish and isconsidered very aggressive.

STSE

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Key Concept Review1. List five services that we rely on ecosystems

to provide.

2. Describe three levels of biodiversity.

3. What is extinction, and how is it related tobiodiversity?

4. Give two examples of how overexploitationof a resource has harmed ecosystems.

Connect Your Understanding5. Suppose a non-native species of beetle is

introduced into a forest. How would youknow if the beetle was becoming aninvasive species?

6. Rhinoceros horns are valued in certaincountries and are used to make daggerhandles. This has led to the illegal huntingof rhinoceros in all parts of Africa. Rhinopopulations are low and still declining.

(a) What is the factor that is affecting therhino population?

(b) What is a possibility if the current trendis not reversed?

7. Identify the misconception in each of thefollowing statements. Rewrite eachsentence so that it is no longer misleading.

(a) Not all species are important, so somehave to be sacrificed.

(b) If an ecosystem appears to have a lot ofone particular species, then it must behealthy.

(c) Biodiversity is unimportant to humans.

(d) A large, smelly swamp is a nuisance tohumans and not ecologically valuable.

8. Easter Island represents an unsustainableuse of ecosystems. You have learned thatfive factors can affect the sustainability ofecosystems. Did all of these factorscontribute to the islanders’ demise? Justifyyour answer.

9. What are three negative ecologicalconsequences of logging within the borealforest ecosystem?

10. Explain the possible threats to biodiversityshown in the photograph below.

Reflection11. Ecosystems provide things that directly

affect you. Do you take these things forgranted? Give an example of how anecosystem specifically helps you. Whichvalue related to the preservation ofbiodiversity do you hold most important?



Question 10


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Great Pacific Garbage PatchThe world’s oceans are so big, it is easy to think that tossinggarbage into them will not really affect the environment.Evidence suggests that the opposite is true. There are greatcircular ocean currents, called gyres, that swirl floating debris totheir centres, and the debris stays there.

The North Pacific Ocean has two large gyres, each thousandsof kilometres across. People passing through them in sailboatshave reported constant encounters with floating garbage. Thisdoes not mean, however, that there is an “island of floating junk”that you could bump into or photograph from space.

It might be better for the environment if there actually weresuch an island. At least we could travel to it and clean it up. Inreality, enormous amounts of garbage, mostly plastic, are spreadout over thousands of square kilometres of ocean. These itemsfloat on or just beneath the surface. Occasionally, the NorthPacific gyre brushes past the Hawaiian Islands and depositsmounds of plastic from across the world onto Hawaii’s beaches(Figure 2.20).



• Different soils have differentcharacteristics that can beassessed. Human activities canhave long-lasting effects onsoil.

• Water can be tested for thepresence of pollutants such asheavy metals, pesticides, andfertilizers.

• Human activities have affectedOntario’s terrestrial and aquaticecosystems in many ways.

Assessing the Impact of Human Activities onEcosystems2.2

Figure 2.20 The amount of plastic in the world’s oceans exceeds 100 million tonnes. Most of ususually encounter this plastic pollution only when it washes ashore as it has done here on Hawaii.

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The Impact of Human PollutionThe United Nations Environment Programme (UNEP) estimatesthat plastic debris kills more than a million sea birds every year.Sea birds, sea turtles, and other animals mistake bits of plastic forfood items. Plastic pieces can last for over 50 years in the ocean,and because they are not digested when eaten, they can go onkilling animals. The animals die from eating plastic items, andtheir remains decompose. The plastic items, however, do not.They stay in the environment and can be eaten by other animals.UNEP reports that cigarette lighters, syringes, and toothbrushesare just some of the items that have been found in the stomachsof dead sea birds (Figure 2.21).


A14 Quick Lab

If Earth Were an Apple

PurposeTo create a model that demonstrates the amount ofland on Earth that is available to grow food

Procedure

1. With a partner, estimate what fraction of Earth’ssurface is available to grow food for the world’shuman population. Record your estimate.

2. Obtain an apple, and place it on the cuttingboard. The apple represents Earth.

3. Cut the apple into four quarters. Three of thequarters represent the oceans of the world. Placethem in the discard pile.

4. Cut the remaining quarter in half. One piecerepresents the land area that is uninhabitable:polar areas, deserts, swamps, and highmountains. Discard one piece. The remainingeighth represents the land area where peoplelive.

5. Cut the eighth into four equal pieces. Three ofthese represent the areas unable to produce foodbecause they are too wet, too stony, too cold, toosteep, or have poor soil. They also representcities, suburbs, highways, malls, schools, parks,industrial areas, parking lots, and many otherplaces where people live and work but do notgrow food. Put them in the discard pile.

6. Carefully peel the 1/32nd slice of Earth. This tinybit of peel represents the surface of Earth’s crustupon which humankind depends to grow food. Itis less than 2 m deep and is a quite fixed amountof food-producing land.

Question

7. Think about your model and the information instep 6. What does this mean for humans and theamount of space on Earth to grow food?

Figure 2.21 This albatross chickdied from plastic consumption.

• apple

• cutting board

• knife


CAUTION: Do not eat anything in the lab.

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Acid Rain and Ontario’s EcosystemsEmissions from a variety of human activities contain pollutantsthat enter the atmosphere and can have wide-ranging effects onthe environment. In Canada, emissions come from mining andrefining metals, electrical power generation, oil and gasoperations, and automobiles. Nitrogen- and sulphur-containingsubstances are two of the most common pollutants in emissions(Figure 2.22).

Once these substances are released into the air, they combinewith water vapour in the air and form acids. An acid is a commontype of chemical. Some acids are safe for the environment. Youeven consume them in foods such as orange juice and saladdressing. However, many acids are not safe and can damageecosystems. The acids formed in the air by emissions fall as acidrain. Acid rain affects soils, vegetation, lakes, rivers, andterrestrial and aquatic animals.

Effects of Acid RainAcid rain damages the waxy coating that protects leaves frominfection. When acid rain seeps into soil, it burns the skin ofearthworms. It increases the acidity of the soil and affects plantroots’ ability to absorb nutrients. Acid rain also makes bodies ofwater more acidic. Shellfish are the most sensitive because theacid in the water dissolves their shells. When lakes become acidicenough, no organisms can survive in them. These lakes have clearblue water but contain no life.


emissions to atmosphere

chemical transformation condensation

precipitationdry fallout

industry transportation mining andrefining metals

power generation

nitrogen-containing substancessulphur-containing substances

nitric acidsulphuric acid

dust, gasesacid rain, fog, snow, and mist

Figure 2.22 The steps involved in forming acid rain

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When scientists discovered how acid rain was caused and itswide-ranging effects, governments put limits on emissions. Inresponse, the mining industry installed scrubbers, which removea large proportion of the damaging chemicals from the emissionsbefore they are released. As a result, acid rain has been reduced.However, it has not been eliminated completely. Countries thathave not implemented these changes continue to produceemissions that cause acid rain. The wind carries these emissionsto other countries (Figure 2.23). Acid rain is an internationalproblem, not just a Canadian one.

Assessing Impacts on EcosystemsWhen we examine pollutants, such as acid rain, in ecosystems,we have to have ways of assessing their effects on soils and water.Understanding the effects of human activities on soils and water,and the organisms that depend on them, helps us to find ways toprevent harm to ecosystems. It also helps us to find ways toimprove the health of ecosystems that have been damaged byhuman activities.


Figure 2.23 The trees in this forest have been damaged by acid precipitation. Thepollutants that caused the acid rain probably entered the atmosphere far from this forest.

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Assessing Soils Soil and water are essential to all ecosystems. Soils are muchmore than just dirt. They are bursting with life. The condition ofa soil indicates the health of any ecosystem that depends on it, aswell as the effects human activities have on it.

To assess the condition of a soil, it is helpful to know whatsoil is. Soil is a loose covering on the ground containing a mixtureof organic matter, minerals, and moisture. Soil quality includessoil profile, soil type, and acidity.

Soil ProfileSoil is made up of distinct layers, as shown in Figure 2.24.

• Topsoil is the uppermost layer in soil. It is composedchiefly of humus, which is decaying organic matter. It alsocontains rock particles and organisms such as bacteria,fungi, insects, and worms.

• Subsoil is the layer below topsoil. It is very compact andhas little or no organic matter except roots of very largetrees and bacteria.

• Bedrock forms the bottom of the soil profile. It is solid rock,and water cannot pass through it. Water travels downthrough the upper layers and is trapped above the bedrock.The bottom of the subsoil gets saturated like a spongesitting in water. The top surface of the ground water iscalled the water table.


topsoil

subsoil

bedrock

water tableground water

Figure 2.24 Soil is composed of subsoil, topsoil, and bedrock.

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Soil TypesThree main soil types are loam, clay, and sandy. Each supportsdifferent varieties of plants, but the most fertile, and the onegenerally preferred for agriculture, is loam.

• Loam soil has rock particles of many different sizes. Thisresults in many pockets that can hold air or water, whichkeeps the soil loose enough that plants can grow into iteasily (Figure 2.25). Loam also tends to have a lot of humus,and it drains well without drying out. The black soil ofHolland Marsh, near Lake Simcoe, is loam (Figure 2.26).

• Clay soil contains particles that are extremely small and sopack tightly together. This prevents the formation of airpockets. Many plant roots do not grow well in clay soil. Claytends to block root growth and trap water, making the soilexcessively wet.

• Sandy soil contains sand particles, which are relativelylarge compared to clay particles. The presence of sandcreates large spaces that permit root growth and air pockets.It also permits water to drain away quickly into the subsoil,carrying essential nutrients away from roots. This makessandy soil much less fertile than loam. Many areas near theGreat Lakes have sandy soil.


soil particle

root cell

water

air space

Figure 2.25 The areas between soil particles are filled with air spaces and water.

Figure 2.26 Farming in the HollandMarsh

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Acidity LevelsAcidity is an abiotic factor that is connected to the chemicalenvironment of soil. Soils vary in their acidity. If you have eversucked on a lemon, you know that it is extremely sour. This iscaused by acid in the lemon juice. By contrast, a banana is notsour at all. However, even bananas are very slightly acidic.

Not all substances are acidic. For example, pure water is not. Itis classified as neutral. To precisely assess acidity levels in soil, aspecial scale is used. It is called the pH scale (Figure 2.27). ThepH of a soil can be measured by testing the moisture in the soilwith specially treated strips of paper that change colourdepending on the pH.

The pH measurement of a substance can be classified as low,neutral, or high. If a soil has a low pH, it is acidic. If it has a highpH, it is called alkaline. If a soil has a pH that falls exactlybetween the two extremes, it is neutral. Most organisms,including plants, prefer a nearly neutral environment. Soil that istoo acidic or too alkaline can damage the tissues of plants andanimals or make it difficult for them to absorb nutrients. Someplants do require slightly acidic or basic pH levels and will growonly under the correct conditions (Figure 2.28).

Human Impacts on SoilsOne of the most devastating effects of human activity on soil issoil erosion. Soil erosion is the loss of soil when water or windwashes or blows it away. The roots of plants normally hold thetopsoil in place. When soil is ploughed, or tilled, the topsoil is


Figure 2.27 pH scale

Figure 2.28 These hen-and-chicksplants require alkaline soil.Gardeners will often add limestoneto soil to raise the pH.

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14acidic

2.0lemon juice

4.2 tomatoes

6.0milk

neutral

8.2 baking soda

10 toothpaste

12ammonia

13.8 drain

cleaner

alkaline

0.5battery acid

7.0pure water

4.6acid rain

5.6 normal

rain8.0

sea water

2.2vinegar

1.0stomach acid

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exposed to wind and water, which can erodeit (Figure 2.29). Overgrazing by livestockanimals, such as cows and sheep, can alsoerode the soil. If livestock eat too many of theplants’ leaves, the plants die. Without plantsto hold the soil in place, the soil erodes. Oncethe topsoil is gone, the land can no longer beused for grazing or growing crops.

Plants draw nutrients from the soil anduse them to build plant tissue. As you learnedpreviously, when plants die, decomposersconsume the dead plants and release some ofthe nutrients in the organic matter back intothe soil. The nutrients can then be usedagain. If the same type of crop is grown in thesame soil year after year, the nutrients in the soil get used up, andthe crops no longer grow well in the soil.

Early in the history of agriculture, farmers learned that theyhad to rotate their crops. Crop rotation is the practice ofplanting a different type of crop in a particular field each year.For example, farmers will plant wheat or corn one year, and thenplant soybeans or alfalfa in the same field the following year.This replenishes some of the nutrients in the soil, especiallynitrogen.

Plants of the legume family, such as soybeans, peas, lentils,and alfalfa, have a symbiotic relationship with nitrogen-fixingbacteria (Figure 2.30). The bacteria supply nitrogen in a usableform directly to the plant. In return, the plant provides thebacteria with other nutrients. Nitrogen-fixing bacteria also livefreely in the soil. By planting nitrogen-fixing plants, the nitrogenin the soil gets replenished. This reduces the need to add chemicalfertilizers to the soil. If farmers do not rotate their crops, theyhave to supply nutrients to the soil by adding fertilizers.

Figure 2.29 Wind is eroding the soil as it is tilled to plant crops.


Figure 2.30 The white bumps onthe roots of this pea plant are callednodules. Each nodule containsmillions of nitrogen-fixing bacteria.

Learning Checkpoint

1. What are the three layers of soil?

2. Describe how sandy soil is different from clay soil.

3. Explain why it is important to know the level of acidity in soil.

4. In what ways can farming contribute to soil erosion?

5. Describe how crop rotation helps restore nitrogen to the soil.

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Assessing Water QualityWater is critical to life, and every community in Ontario has someplan to manage its use and protect its quality. Being able to assesswater quality and act responsibly to protect it is essential forsustainable ecosystems in Canada and around the world. Manydifferent aspects of water are used to assess its quality.

Aquatic OrganismsHealthy aquatic ecosystems are full of organisms. These includeones that are easily recognizable, such as fish, large plants, andinvertebrates. On the microscopic level, there are plankton, whichare tiny plantlike and animal-like organisms, and bacteria andviruses.

Sometimes, the types and quantities of species present in thewater can indicate that the water is unsafe. For example, certainbacteria can cause serious health problems if they are present inlarge enough numbers. In summer, lakes are closed for swimmingbecause of temporary high levels of micro-organisms that cancause diseases such as ear infections and intestinal infections.

The presence or absence of some organisms can indicate thatwater is polluted. Indicator organisms include certain insects andinsect larvae, shrimp, clams, and worms (Figure 2.31). Differentorganisms prefer different conditions. For example, someorganisms can survive in polluted water, while others cannot.


waterboatman mosquito

larvawaterstrider

mayflynymph

midge larva

clamstonefly nymph

caddisfly larva

leech

dragonfly nymph

flatworm

Figure 2.31 The number and types of aquatic organisms indicate water quality.

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Figure 2.32 A caddisfly larva

OxygenJust as terrestrial organisms need the oxygen in the air, aquaticorganisms need the oxygen gas that is dissolved in the water.

• Dissolved oxygen measurements give the level of oxygenpresent in water. Table 2.4 shows the levels of dissolvedoxygen needed by various organisms. If levels of oxygendrop below a certain level, fewer organisms are able to livein that body of water. For example, caddisfly larvae preferwater that has a high level of dissolved oxygen (Figure2.32). If the oxygen level falls, the larvae will die.

• Biological oxygen demand (BOD) measures how quicklyoxygen is used up by micro-organisms in a given body ofwater (Table 2.5). BOD is an effective test for certain typesof water pollution. Polluted water can actually promote thegrowth of some micro-organisms, which feed off thepollution. These organisms use up oxygen, which meansoxygen is removed from the water at a high rate. In additionto the possible toxic effects the pollution can have on anaquatic ecosystem, its presence results in low oxygen levelsin the water. This can cause organisms to die.


Dissolved Oxygen(mg/L) Aquatic Organisms

8 Large numbers of diverse species thrive.

6 Mayflies, stoneflies, and beetles start to disappear.

4 Freshwater shrimps, midge larvae, and worms can survive.

2 Midge larvae and some worms can survive.

Table 2.4 Levels of Dissolved Oxygen Needed by Aquatic Organisms

Water Sample BOD Value (mg/L)

Clear lake water with few organisms 0–5

Clear lake water with many organisms 8–20

Slightly polluted lake water 20–100

Highly polluted lake water 100–10 000

Table 2.5 Typical BOD Values for Selected Water Samples

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AcidityAs with soil, most aquatic organisms prefer a neutralenvironment. If the acidity increases, the diversity of plants andanimals that live in this water decreases. Most fish die if thewater’s pH falls to 4.5.

Phosphorus and NitrogenFertilizers are applied to fields and gardens to supply plants withnutrients, such as the elements nitrogen and phosphorus. Whenthe field or garden is watered, the water dissolves the fertilizerand this provides the nutrients to the plants. However, waterfrom the garden then runs into local waters and streams andtakes these nutrients with it. If the stream runs into a pond orlake, the high levels of nutrients in the water cause algae to growrapidly. This process is called eutrophication. Eutrophication isthe addition of nutrients to an aquatic ecosystem causingincreased growth of plants such as algae (Figure 2.33). As thelarge amount of algae dies and decomposes, oxygen is depletedfrom the water. The resulting low amount of oxygen in the watermay cause fish and other animals to die. Eutrophication is a hugeproblem in aquatic ecosystems in areas where chemicalfertilizers are widely used.


Sunlight

(1) Nitrogen and phosphorus in surface run-off enter lake.

(2) Nutrients fertilize aquatic plants on the surface.

(4) Less light can penetrate, and plants below the surface die.

(5) Decomposers feed on dead plants, depleting the oxygen in the water.

(6) Animals eventually die from lack of oxygen.

(7) Lake can only support aquatic plants at the surface.

(3) Surface aquatic plants increase.

Figure 2.33 The steps in the process of eutrophication

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Heavy Metals Some kinds of metals cause illness if they are present in water ineven very tiny amounts. Mercury belongs to a group of substancescalled heavy metals. They are called heavy metals because theyhave a density of 5 g/mL or higher. This means that they are fiveor more times heavier than an equal volumeof water. Other heavy metals include copper,lead, and cadmium. There are many sourcesof heavy metals including batteries, whichoften contain cadmium, and compactfluorescent light bulbs, which containmercury. Both of these kinds of devices mustbe disposed of responsibly.

Many industrial processes release heavymetals directly into the environment. Forexample, all coal-fired power plants,incinerators, and steel mills emit mercuryfrom their smokestacks, because mercury isfound naturally in coal. Mercury in theatmosphere usually settles in water. Algaeabsorb very tiny amounts of mercury fromthe water. Over time, mercury builds up intheir tissues. The gradual build-up of asubstance in an organism’s body is calledbioaccumulation. Unfortunately, this isnot the end. The contaminated algae areconsumed by zooplankton, and themercury bioaccumulates in their tissues. Ina process called biomagnification, themercury becomes more and moreconcentrated in each link in the food chainas one animal eats many contaminatedanimals (Figure 2.34). Many predatoryfish, including some salmon and trout, have levels of mercury high enough to betoxic if they are eaten by humans and other animals.

Health problems caused by heavy metalsinclude kidney and lung disease, immunesystem disorders, cancer, sterility in men,and infertility in women.


water

producers

zooplankton

small fish

large fish

fish-eating birds magnification of chemical’s concentration

1

1000

10 000

100 000

1 000 000

10 000 000

Figure 2.34 The steps involved in biomagnification

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Aboriginal farmers developed asystem of cultivation known as"the three sisters." Find out whatcrops made up the three sistersand what advantage each cropprovided. Begin your research atScienceSource.

Take It Further PesticidesPesticides are chemicals that kill unwanted organisms, usuallyones that attack crops and reduce their yield (Figure 2.35). Somepesticides last a long time in the environment, though in Canadathese kinds are strictly controlled or banned. Just as heavy metalscan biomagnify, so can some long-lasting pesticides. One suchpesticide is DDT. Used in Canada until the 1970s, it built up inmany top level predators, such as peregrine falcons. It made theireggshells so thin that few eggs hatched, and their populationsdeclined. In Canada, the peregrine falcon almost became extinctdue to DDT use. Modern pesticides are designed to last onegrowing season and then break down into less harmful substances.

DDT has not been banned worldwide because in some cases,its societal benefits outweigh its environmental risks. DDT is usedresponsibly in mosquito-infested parts of Africa in homes and onmosquito nets. This saves millions of lives by combatting an oftenlethal disease called malaria, which is carried by mosquitoes.


Learning Checkpoint

1. How does the presence of certain bacteria affect water quality?

2. Explain what biological oxygen demand is.

3. Explain why the presence of nitrogen and phosphorus in water canthreaten ecosystems.

4. Give an example of a heavy metal.

5. Explain the process of biomagnification.

Figure 2.35 Pesticides help reduce the amount of crops lost to pests. However, in addition tokilling the pest species, pesticides can also kill other non-target species. This can reduce localbiodiversity.

DrawingConclusions

When we ask questions, wecan analyze ideas and drawconclusions. Use athree-column chart to help youdraw conclusions from thereading you have done abouthuman interactions withecosystems. Label the firstcolumn “I read” and record aphrase or sentence from thetext. Label the second column “I asked” and write down yourquestion(s). Label the finalcolumn “Therefore” and recordyour conclusion.

During Reading

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A15

Increasing Biodiversity in Your Community

To achieve sustainability, we have to maintain alllevels of biodiversity: genetic, species, andecosystem diversity. But we must remain part ofour ecosystems to exist, so we have to find waysto balance human needs with maintainingbiodiversity.

1. Working in groups, think of an area in ornear your community where biodiversitycould be increased. In a city, this could be acity park, a waterway running through adensely populated area, or a vacant lot. In arural farming community, it could be anundeveloped patch of land betweencultivated areas. In a community locatedwithin a forest, it might be the entire areasurrounding the community.

2. Brainstorm ways to increase biodiversity inyour chosen area. Try to be as practical aspossible. • How will you lessen or eliminate the

effects that pollution, invasive species,and habitat change have had in the area?

• How could you improve the water qualityand soil quality?

• What species do you want to introduce intoyour area? How will their needs be met?

• How will human needs be met? Willhumans use the area? If so, how will anypossible impacts on the biodiversity beminimized?

3. Present your action plan to the class. Beprepared to answer any questions.


A16 Skill Builder Activity

Extrapolation is the process of estimating the value ofa measurement beyond the known or measuredvalues of a set of data. To make predictions aboutwhat may happen in the future, scientists extrapolatefrom existing data. For example, you can estimatehow tall you will be next year based on your heightmeasurements over the last five years.

Use Figure 2.36 to answer the followingquestions.

1. By how much did the world’s population increase from 1980 to 2000?

2. Extrapolate to predict the world’s populationin 2020.

3. What assumptions did you make when youextrapolated from the data?

Extrapolation

Popu

latio

n (b

illio

ns)

0

2.0

3.0

4.0

5.0

7.0

6.0

8.0

1940 1960 1980 2000 2020

Year

World Population

Figure 2.36

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A17

Part A — Fertilizer and Soil Fertility

Question How does using fertilizer affect the fertility of soil?

Design and Conduct Your Investigation

1. Create a hypothesis to explain how fertilizer couldaffect soil fertility. For example, adding fertilizerincreases soil fertility.

2. Once you have developed your hypothesis, thinkabout how you can test it. Consider the followingquestions.

• How will you measure fertility?

• There are many different types of fertilizer.What type of fertilizer will you use, and howmuch should you use? How often will youapply it?

• What kind of plants should you use? Forexample, will you grow plants from seeds, orwill you use seedlings?

• What aspect of a plant will you measure (forexample, plan height, leaf colour)?

• What type of soil will you choose? Pottingsoil? Soil from your area? How much shouldyou use?

• What containers will you use to grow yourplants in? How many will you need?

• How long will your experiment run?

3. Decide what variables you will control and whatvariables you will measure. For example, will youcontrol the amount of water the plants get?

4. Decide what the control should be for theinvestigation. For example, will you grow twoidentical kinds of plants and treat eachdifferently?

5. Decide what variables you will measure in theexperiment, and decide how you will measurethese variables. Design a data table in which youcan record your measurements.

6. Write out your procedure. Have your teachercheck it before you carry out your investigation.

7. When you have finished your investigation,dispose of your materials as instructed by yourteacher. Clean your work area, and wash yourhands.

8. Analyze your data. Did your results support yourhypothesis? Explain why or why not.

9. ScienceSource Use the Internet and othersources to find out about fertilizer use inagriculture (Figure 2.37). In what ways canfertilizer use affect the soil?

10. Extrapolating from your data and from yourresearch, what conclusions can you draw aboutfertilizer use and soil fertility?

Testing the Effects of Fertilizer on Soiland Aquatic Ecosystems

SKILLS YOU WILL USE� Developing a hypothesis� Evaluating whether data

support a hypothesis

Skills References 2, 6, 9

Figure 2.37 Fertilizer being applied to a field

Key ActivityDI Design a Lab

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A17 Design a Lab (continued)

Part B — Fertilizers and AquaticEcosystems

QuestionHow does fertilizer use affect aquatic ecosystems?

Design and Conduct Your Investigation

1. Create a hypothesis to explain the effectsfertilizer might have on aquatic ecosystems.

2. Once you have developed your hypothesis,consider the following questions.

• How will you create an aquatic ecosystem?

• What plants will you use? How manydifferent types will you use?

• Will you use animals as well as plants?

• What type of fertilizer will you use and howmuch?

• What will you measure in the aquaticecosystem?

• How long should the investigation run?

3. Decide what variables you will control and whatvariables you will measure. For example, will youcontrol the amount of sunlight the ecosystemsget?

4. Decide what the control should be for theinvestigation. For example, will you construct twoidentical aquatic ecosystems and treat eachdifferently?

5. Decide what variables you will measure in theexperiment, and decide how you will measurethese variables. Design a data table in which youcan record your measurements or observations.

6. Write out your procedure. Have your teachercheck it before you carry out your investigation.

7. When you have finished your investigation,dispose of your materials as instructed by yourteacher. Clean your work area, and wash yourhands.

8. Analyze your data. Did your results support yourhypothesis? Explain why or why not.

9. ScienceSource Use the Internet and othersources to find out about the effects of fertilizeruse on the sustainability of aquatic ecosystems(Figure 2.38).

10. Extrapolating from your data and from yourresearch, what conclusions can you draw aboutthe effects of fertilizer use on the sustainability ofaquatic ecosystems?

Figure 2.38 Aquatic ecosystems can be very near fields.

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A18 Quick Lab

At the Hubbard Brook Experimental Forest, ecologistscarry out large-scale long-term ecologicalexperiments. Because forests take up a great deal ofwater and return water vapour back to theatmosphere through transpiration, ecologists believedthat deforestation may affect the water cycle. You willbe provided with actual data from a 30-yearexperiment, which continues to this day.

One set of data is from a forested watershed inwhich all the trees were clear-cut in 1965 (Figure2.39). In 1966, 1967, and 1968, two herbicides wereapplied to the entire watershed to prevent anyvegetation from growing again. The other set of datais from a neighbouring watershed where the treeswere left untouched. In both watersheds, a weir wasbuilt to measure the amount of water in the streamflowing out of the watershed (Figure 2.40).

PurposeTo analyze data to determine the short-term andlong-term effects deforestation has on the amount ofwater flowing out of a watershed

Procedure

1. Plot the data for both watersheds from 1958 to1970 only. Use different colours to represent thetwo different watersheds.

2. Study the graphs for both watersheds. Whattrends do the data show?

3. Does cutting all the trees in a watershed increasewater flow over the short term? Is there asignificant difference? Explain your reasoning.

4. On the same graph, plot the remaining data forboth forests from 1970 to 1988.

Questions

5. Does cutting all the trees in a watershed increasewater flow over the long term? Is there asignificant difference? Explain your reasoning.

6. Data were collected for seven years before thetrees were cut down.(a) Why is this information important? (b) What misinterpretations could have been

made without the first seven years of data?

7. (a) What was the control in this experiment? (b) Why is it necessary to have a control?

8. If the experiment had been stopped five yearsafter the forest was cut, would the conclusionshave been different? What is the importance oflong-term research?

9. If a community wishes to increase the water in its reservoirs, would cutting down trees be a goodsolution? Explain.

10. Extrapolate data points for an additional fiveyears, and infer any future trends.

Deforestation and Watersheds

• data sets • coloured pencils

• graph paper


Figure 2.39 The deforested watershed

Figure 2.40 A weir

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Key Concept Review1. Which has bigger rock particles, clay soil or

sandy soil?

2. Describe the three layers of soil.

3. Why is humus important for healthy soil?

4. Why is it important to test for bacteria inwater reserved for human use?

5. What indicators can be used to test waterquality?

6. How is the water table connected to thesoil?

7. Define a heavy metal, and give threeexamples.

Connect Your Understanding8. Explain why topsoil is a vitally important

layer of soil.

9. At which level of the food chain doesbiomagnification have the most impact?Explain.

10. What properties of plastic make it adangerous pollutant in aquatic ecosystems?

11. Explain how the presence of coal-firedelectricity plants can affect the ability oflakes to support life.

12. Suppose that there has been a suddengrowth of algae in a lake in cottage country.

(a) Suggest three possible causes for thissituation.

(b) Explain what could happen in the lake.

13. Manure is often used by gardeners tofertilize soil. How might this be effective inreplenishing soil nutrients?

14. (a) What is the ecological problemillustrated in the photo below?

(b) Name the human activity that may havecaused the situation.

15. Acid rain is not just a Canadian problem. Itis an international problem. Justify thisstatement.

16. In the 1980s, lakes and forests in easternOntario were affected by acid rain. Describethe effects the acid rain might have had onthe terrestrial and aquatic ecosystems.

Reflection17. You can be a part of solution to the various

problems you learned about in this section.Does your lifestyle affect neighbouringbodies of water? Identify any habits thatyou or your family have that may have animpact. How can you change your habits sothat you do not negatively affect the watercycle?



Question 14


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Dr. David Suzuki is an environmentalist,broadcaster, and scientist. As the cofounder of theDavid Suzuki Foundation, he has devoted anenormous amount of his time to saving theecosystems of the world. The foundation focusseson four main areas: oceans and sustainablefishing; climate change and clean energy;sustainability; and the Nature Challenge. Throughscience and education, the foundation encouragessolutions that will conserve nature while achievingsustainability within a single generation. The useof science and education are key to how Suzukiincreases environmental awareness.

The Nature of Things is a television sciencemagazine show, which is hosted by Suzuki. Suzukiuses the show to engage viewers in the naturalworld, point out threats to human well-being andthe environment, and offer ideas for how toachieve a more sustainable future. With 6.6 billion


Figure 2.41 Dr. Suzuki visits students at William Lyon Mackenzie Collegiate tocongratulate them on creating a renewable energy project.

human inhabitants, the biosphere is undertremendous pressure to support everyone’s needs.

Suzuki is inspired by the energy of today’syouth. He is encouraged to see students usingtools such as blogs, email, podcasts, and socialnetworking sites to spread the message aboutprotecting the biosphere. The future dependson it!

Questions

1. What has David Suzuki done to increaseawareness of sustainable ecosystems?

2. Go to ScienceSource to research DavidSuzuki’s Nature Challenge. List three thingsyou can do right now to live a greener life. Trythem out for a week. How easy or hard werethey to do?

CAREERS in ScienceInvestigating

Great CANADIANS in Science David Suzuki

Figure 2.42 Dr. Suzuki answers questions at apress conference about Canada’s environmentalpriorities.

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As people and businesses become more aware ofthe stresses on ecosystems, they are starting tothink more critically about their actions. Anecological consultant helps people make thosedecisions by doing many of the following things:

• providing data and recommendations onlessening impacts on the environment

• doing landscape assessment and planning

• ecological monitoring and research

• creating materials for educational workshopsand public consultations

• providing logistical support for municipalenvironmental strategies

• providing expert testimony in environmentaltrials

The construction of a new highway through theenvironmentally sensitive Red Hill Valley inHamilton is a typical project that requires theservices of an ecological consultant (Figure 2.43).On this project, ecological consultants ensured

that environmental concerns were beingaddressed before any construction began.

A consultant’s job varies greatly depending onthe client, the season, and the type ofenvironment. However, it includes writingproposals and reports, working with clients,making presentations, and managing supportstaff. Field work is mostly done during the summer(Figure 2.44), and research, designs, and reportsare mostly done during the winter.

Most ecological consultants are passionateabout their work. They help to find a balancebetween ecosystem health and human needs.

Questions

1. Write a short paragraph explaining what thetypical day or week in the life of an ecologicalconsultant would look like.

2. Go to ScienceSource to research whateducation or training is needed to becomean ecological consultant.

Figure 2.43 An overpass being built for the Red Hill Valley Expressway in 2003.The expressway opened in 2007.

Figure 2.44 Ecological consultants spendtime in the field collecting data.

Science in My FUTURE Ecological Consultant

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Key Concept Review1. What negative effect can habitat change

have on native species?

2. (a) What is causing climate change?

(b) Describe the impact climate change ishaving on an Arctic species.

3. What is the relationship between dissolvedoxygen and biological oxygen demand?

4. Classify the following pollutants as eitherpoint source or non-point source.

(a) excess fertilizer from fields

(b) pesticide residue from local gardens

(c) discharge of waste water from a cruiseship

(d) leaking storage tanks

(e) a leaking landfill

(f) animal waste treatment facility

(g) sediment from a clear-cut forest

(h) stormwater from an urban parking lot

(i) bacteria from pet wastes

5. Give an example of overexploitation in amarine environment.

6. List some chemical indicators that can beused to test water quality.

7. (a) What is acid rain?

(b) What are the causes of acid rain?

(c) List ways that acid rain affects aterrestrial ecosystem.

8. If too much sewage is added to water, theaquatic organisms may die due to lack ofoxygen. Explain how this might occur.

9. Explain habitat fragmentation, and suggestways in which it could degrade the qualityof an ecosystem.

10. What advantages might an introducedspecies have when competing with nativespecies?

Connect Your Understanding11. Explain how irrigation systems might

actually cause a decrease in water quality.

12. Many potential home buyers want lots oftrees around their homes. A housingdeveloper builds a residential community ina forested area. To show his ecologicalresponsibility, he leaves patches of theforest untouched and builds roads toconnect the various parts of thedevelopment. Critique how ecologicallyresponsible the developer’s actions are.

13. The human activity pictured below mayaffect biodiversity. Create a concept mapthat shows how the activity may affectbiodiversity. c

a

a

k

k

k

k

k

k

k

k

k

k

k

k

k




tk

2 CHAPTER REVIEW

Question 13

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14. Suppose that a homeowner wishes to start asmall garden in her backyard. Why is itimportant that she determine the type of soilshe has before planting any vegetables?

15. How might biodegradable plastics helpreduce pollution?

16. Consider the following hypotheticalsituation. Suppose that a factory emits anumber of pollutants that cause healthproblems in young children and the elderly.This factory also employs 50 percent of thetown’s residents directly and indirectly, andclosing the factory would cause severefinancial hardship in the town. Forcing thefactory to clean up its emissions would alsocause the company to lose money and makeit difficult for it to compete with similarcompanies. You are the mayor. Suggest anaction plan for your town that will help todeal with this crisis.

17. The data in the table gives the averagedissolved oxygen values in the Gulf ofMexico. Normal seawater has at least 6.9 mg/L.

(a) Graph the data.

(b) Which months have dissolved oxygenlevels that are too low to support aquaticlife?

(c) The name “dead zone” is given to thezones in aquatic ecosystems that do nothave enough oxygen to support life.Why is this name appropriate?

(d) Create a hypothesis that might explainthe trends in the data.

(e) What changes could be made to correctthis situation?

Reflection18. The World Water Council ranked Canada

second out of 147 countries in terms ofwater sustainability. However, Canadaranked 129th in terms of responsible wateruse. How could you change your actions toimprove this placement? c

t

t

t

t

c

a

a

a



With a partner, share and summarize some of thequestions you posed during this chapter. Compareany conclusions you drew. Write a three-sentenceresolution about ways that you will both be moreresponsible in how you deal with ecosystems inthe environment. Share your resolutions withanother pair of students.

After Reading

Unit Task Link

In this chapter, you have learned about thenegative effects human activities can have onecosystems. In the Unit Task, you will bedesigning a sustainable community. Think aboutways you could lessen habitat loss/fragmentation,pollution, and overexploitation in your sustainablecommunity.

MonthDissolvedOxygen (mg/L) Month

DissolvedOxygen (mg/L)

Jan 1 8.5 Jan 15 9.0

Feb 1 8.5 Feb 15 9.0

Mar 1 8.0 Mar 15 7.5

Apr 1 5.0 Apr 15 3.5

May 1 2.0 May 15 3.0

June 1 0.0 June 15 1.0

July 1 1.0 July 15 0.0

Aug 1 0.0 Aug 15 0.0

Sept 1 0.0 Sep 15 0.0

Oct 1 3.0 Oct 15 4.5

Nov 1 6.5 Nov 15 7.5

Dec 1 8.0 Dec 15 7.5

Dissolved Oxygen Values

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3 Governments, groups, and individualswork together to promote sustainableecosystems.

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Governments, groups, and individuals work to promote sustainable ecosystems. 91

This farmers market is in the Kitchener area. Usingfarmers markets is one of the many actions thatgroups and individuals are taking to live in a moresustainable way.

Skills You Will UseIn this chapter, you will:

• find sources of information that are relevant to thequestions you are researching

• select, organize, and record the relevant information youfind as you research a topic


• assess the impact of a human activity that threatens thesustainability of an ecosystem

• evaluate the effectiveness of actions people are taking toensure that ecosystems are sustainable.

Why This Is ImportantYou need to know what actions governments, organizations,and individuals are taking to correct the damage humanshave done to ecosystems. Once you know the things they aredoing, you can evaluate whether their actions are effective.You can also decide what types of actions you can take tohelp the environment.

Preparing to Select and OrganizeInformation

When you are researching a topic, not all the informationthat you read will be useful to you. Get in the habit ofdeciding what’s truly important and what’s not essential.As you think about issues related to sustainableecosystems, skim section 3.1 and decide whichinformation could be truly useful and which is just niceto know.

Key Terms

• at risk • ecological footprint • endangered• environmental steward • ex-situ conservation• extirpated • in-situ conservation • integrated pestmanagement • special concern • threatened

Before Writing

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Lake Erie: “The Comeback Kid” Lake Erie, the shallowest and smallest of the Great Lakes, can bethe ultimate Canadian getaway. Because the lake is shallow, itwarms quickly in the summer. This makes it popular for manydifferent recreational activities (Figure 3.1).

In the 1970s, Lake Erie was very different. Its water was fullof sewage, farm chemicals, and industrial chemicals (Figure 3.2).This chemical “soup” had the potential to cause a collapse of theentire lake ecosystem. The most visible example was runawayalgae growth, which left an unsightly scum across the lake. Whenthe algae grew, it choked out other organisms. When it died, its decay removed dissolved oxygen from the water, causing massivefish kills.

How did this come about? There are many pressures on thelake. More than 12 million people live near its shores. The LakeErie watershed is one of the most intensely farmed regions on thecontinent. With population growth came industry. Many people,though not all, operated for decades on the assumption that thelake was so large that it could safely absorb any amount ofsubstances put into it by humans. By the 1970s, the effects of thisapproach had produced a smelly lake filled with sick or dead fish.No one wanted to go near Lake Erie.



• Conservation biology works toprotect biodiversity, partly byassessing which species areat risk of extinction anddeveloping strategies to protectthese species.

• Species at risk are protected intheir own surroundings byimproving their habitat or byremoving them from the wilduntil their wild habitats can berestored.

• Governments use laws to enact programs to protectecosystems.

Government Action to Protect Canada’sEcosystems

Figure 3.1 Many people enjoy Lake Erie.

3.1

Figure 3.2 A pulp and paper milldumps polluted waste water directlyinto Lake Erie in the 1970s.

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Governments Take ActionIn 1978, the United States and Canadian governments signed theGreat Lakes Water Quality Agreement. Its goal was to restore thechemical, physical, and biological integrity of the Great Lakes in aco-ordinated way. As a result, the Ontario provincial governmentand various U.S. state governments created management plans toclean up each of the Great Lakes. One of the many actionsproposed in Lake Erie’s management plan was to restore wetlandsalong its shores. In addition to restoration projects, the EssexCounty Stewardship Council has helped private landowners createnew wetlands on their land. These wetlands filter the waterentering the lake and remove contaminants from it. The amountof chemical fertilizer, pesticide run-off, and untreated sewageentering the lake was also reduced. As a result, Lake Erie hasmade a significant recovery, though there is still much work to do.

Lake Erie’s ongoing restoration is an example of the power ofcollective action. When governments, groups, and individualswork together for a common purpose, great things are possible.

93Governments, groups, and individuals work to promote sustainable ecosystems.

A19 Quick Lab

Modelling a Wetland

Plants can purify water as they live and grow. In thisactivity, you will investigate this process.

Purpose

To model a wetland removing chemicals from water

Procedure

1. Fill a beaker with 50 mL of water.

2. Add five drops of phenol red solution to thebeaker, and use a straw to blow bubbles into ituntil the solution just turns yellow.

3. Fill two test tubes three-quarters full with thesolution.

4. Place an aquatic plant into each test tube, andseal each test tube tightly with a stopper.

5. Wrap one of the test tubes with aluminum foil.Put the foil-wrapped test tube in a dark place,and place the unwrapped test tube under abright light. After 20 min, observe each one.

Questions

6. The colour change that occurred in step 4 was aresult of removing carbon dioxide from thesolution. Consider which tube the colour changeoccurred in, and explain how carbon dioxide wasbeing removed.

7. Explain how this model demonstrates the abilityof a wetland to purify water.

Materials & Equipment• 50-mL beaker

• 2 large test tubes and stoppers

• warm water

• phenol red indicator

• straw

• 2 aquatic plants

• aluminum foil

• bright light source

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Conserving BiodiversityThe modern science of conservation biology seeks tounderstand and protect biodiversity. Part of this task includesassessing which species are most in danger of extinction as wellas developing strategies to protect them.

Species at RiskIf you had strolled through meadows near Peterborough sometimein the 1900s, you might have seen the bright blue wings of a Karnerblue butterfly as it flew from plant to plant. Today, this would beimpossible because the butterfly no longer exists in Ontario. Luckily,it still exists in small populations elsewhere in North America.

Around the world, extinctions are happening at a rapid rate.But species do not become extinct overnight. When populationsof a species decline over time, the species may be at risk. At riskmeans any native species that is in danger of becoming extinct ordisappearing from a region. There are different levels of risk(Table 3.1).


Figure 3.3 Some at-risk species inOntario. (a) The Karner blue butterflyis extirpated. (b) The eastern prairiefringed orchid is endangered. (c) Theeastern Massasauga rattlesnake isthreatened. (d) The red-headedwoodpecker is of special concern.

Level of Risk Definition

Extirpated A species that no longer exists in Ontario but still occurselsewhere

Endangered A species that faces extinction or extirpation

Threatened A species that is at risk of becoming endangered if limitingfactors are not reversed

Special concern A species with characteristics that make it sensitive tohuman activities or natural events

Table 3.1 Definitions of Some Risk Levels for Species

(a) (b)

(c) (d)

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During Writing

Making Notes

As you research, take notes inpoint form. Never copy word forword. Instead, choose keywords, definitions, and anydirect quotes that will supportyour writing purpose.

There are currently over 200 species at risk in Ontario (Figure 3.3). There are two conservation strategies thatgovernments and groups are using to protect biodiversity.

Conservation StrategiesOne problem in conserving biodiversity is that plants and animalsdo not recognize national boundaries. In order to co-ordinateconservation efforts, governments of different countries useinternational treaties. A treaty is an agreement, usually betweennations, in which they agree to do certain things to achieve acommon goal. The Convention on Biological Diversity is thename of an international treaty whose goals are to conserveEarth’s biodiversity and to use this biodiversity in a sustainableway. The Convention on Biological Diversity has been signed by161 countries, including Canada. It makes use of two broadstrategies: one is to protect species in human-made environmentssuch as zoos, while the other protects species in their nativehabitats.

Protecting Species in Human-Made Habitats The black-footed ferret was extirpated in Canada in 1937, and bythe 1980s, only 18 individuals remained in Wyoming. Thedecision was made to capture these individuals and take them tovarious zoos, including the Metro Toronto Zoo. This is anexample of ex-situ conservation (Figure 3.4).


Figure 3.4 The Metro Toronto Zoo maintains a population of black-footed ferrets throughits captive breeding program.

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Figure 3.5 Constructed 120 mbelow the ice on an island in theArctic Ocean, the Svalbard SeedBank can conserve up to 4.5 millionseeds. These seeds can act as abackup for any plants that havebeen lost due to accidents,mismanagement, or naturaldisasters.

Ex-situ conservation conserves species by removing themfrom their natural habitats. This strategy is used when a species’habitat is threatened or no longer exists, or if the existingpopulation is extremely small. The at-risk individuals are taken tozoos, botanical gardens, or reserves.

Zoos play an active role in preserving biological diversitythrough breeding programs and other efforts. Many zoos acrossNorth America participate in Species Survival Plans (SSPs). SSPsare breeding programs specifically for species threatened withextinction. The strategy seems to have worked for the black-footedferret. The Metro Toronto Zoo’s SSP has been very successful, andhundreds of ferrets have been reintroduced to protected areas inthe U.S. prairies. The zoo and various other organizations arecurrently developing plans to reintroduce the ferret intoGrasslands National Park in Saskatchewan.

Seed banks are an additional ex-situ conservation strategy(Figure 3.5). Seeds of endangered plants and rare crop plants canbe stored in seed banks. Seed banks may be used to maintain theability to restore the population even if it completely disappearsfrom the wild.

Protecting Species in Their Native Habitats Ex-situ conservation is considered a strategy of last resort. In-situconservation focusses on conserving species in their naturalsurroundings. In-situ conservation uses many strategies, but themain one is protecting species’ habitats. For example, theendangered eastern loggerhead shrike needs short grasslandssurrounded by trees, shrubs, and hedgerows (Figure 3.6). Muchof this habitat has been lost by farmers removing hedgerows andconverting pastureland to other crops. By getting farmers topreserve their pastureland and hedgerows, the shrike’s habitat ismaintained and the population may increase.

Another strategy is to help protect a species from its predators.For example, female Blanding’s turtles leave their eggs in buriednests. The eggs are vulnerable to raccoons and coyotes, who dig upthe nests. One strategy is to protect nest sites by fencing them off.

Other strategies include cleaning up or restoring habitat orisolating a habitat from human activity by creating reserves. Foranimals, this usually means establishing large enough landreserves to allow the population to recover to sufficiently largenumbers.

Recall that biodiversity means much more than just havingmany different kinds of species in an ecosystem. A population


Figure 3.6 A loggerhead shrike

WORDS MATTER

“In situ” is Latin for in the originalplace, and “ex situ” is Latin for outof the original place.

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within an ecosystem must have sufficient genetic diversity to beable to adapt to changing circumstances and to evolve over time. When a large population is brought back from just a fewsurviving pairs, all the offspring are very closely related. Asingle disease could wipe out the entire population in oneepidemic. This problem rarely occurs in a healthy, geneticallydiverse population. In-situ conservation helps keep organismsinterconnected with their habitat and, over time, helpsre-establish genetic diversity.

Protecting Endangered SpeciesThe American badger is endangered in Ontario(Figure 3.7). Fewer than 200 individuals remain inisolated pockets, mostly on private land. In 2007,the Ontario government passed the EndangeredSpecies Act. This law prohibits killing, capturing,possessing, selling, or trading species that areendangered in Ontario. The law not only protectsat-risk species, it protects their habitats as well. Thismeans that it becomes illegal to damage or destroyecosystems that the species depends upon. Thisgives developers, local governments, and people wholive or work in the habitat direction as to what is oris not permissible in a given situation. For example,landowners that have American badgers on theirproperty are responsible for preserving the badgers’habitat. The law has some flexibility so that localconcerns about resource use in a particular habitatcan be addressed. However, individuals or groupsthat ignore the law can be accountable andfinancially liable for repairing the damage they cause.


Figure 3.7 The badger’s main food is woodchucks andrabbits, which it catches by digging into their burrows.

Learning Checkpoint

1. What is the difference between a species that is endangered and one thatis threatened?

2. What is a treaty?

3. What are the two main conservation strategies endorsed by the Conventionon Biological Diversity?

4. Which of the two strategies in question 3 is considered to be a strategy oflast resort? Why is it a last-resort strategy?

5. Explain the importance of genetic diversity within a species.

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Establishing Protected AreasEstablishing protected areas is one method to slow down the lossof biodiversity. Protected areas include national and provincialparks, wildlife reserves, and marine sanctuaries. Choosing whichareas to protect can be a challenge. Worldwide, conservationbiologists have identified “biodiversity hot spots,” areas that havemany unique ecosystems and whose biodiversity is threatened(Figure 3.8). These areas contain species found nowhere else onEarth. Many of these species are endangered.

The Role of ParksIn Ontario and the rest of Canada, parks and wilderness areasprotect ecosystems by keeping them relatively undisturbed.Leaving ecosystems undisturbed helps conserve biodiversity.


Figure 3.8 The biodiversity hot spotsare shown in orange on the map.

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Another role of parks is to allow humans to enjoy theseecosystems. Sometimes, this is difficult. For example, AlgonquinPark is one of Ontario’s larger provincial parks, but it is also oneof the most heavily visited (Figure 3.9). Parks officials work hardto balance humans’ need for recreation with ecosystems’ need toremain undisturbed.

Creating Action Plans to Restore EcosystemsAs we have seen, many human activities cause damage to thenatural environment. Remedial action plans involvegovernments, industries, and community groups workingtogether. For example, the St. Lawrence River near Cornwall hadmany environmental problems, including bacterial andheavy-metal contamination and habitat destruction. The firststage of the remedial action plan for the area was to identify thespecific causes of the problems. In the next stage, governmentagencies, industry representatives, and community groups met todevelop specific plans to fix the problems. As a result, Cornwall’smunicipal government improved its sewage treatment plants toreduce bacterial contamination in the river. Domtar Fine Papers’pulp and paper mill improved its waste water treatment process toreduce the amount of heavy metals entering the river. Also,various agencies built artificial reefs and small wetlands along theshore to improve fish habitat.

The third stage of remedial action plans is to monitorconditions to check that the actions taken are working. InCornwall, the actions seem to have worked. Water quality as wellas fish diversity and populations are starting to improve. Butthere is still more work to be done.


Figure 3.9 Algonquin Park receives about six million visitors a year.

Suggested STSE Activity •A20 Decision-Making Analysis on page 102

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Many wetlands in Ontario have been threatened bypopulation growth, farming, and industrial activities. One majorfocus of remedial action plans is habitat restoration, such asreturning a disturbed wetland to a condition as close to itsoriginal state as possible (Figure 3.10). For example, the OshawaSecond Marsh has been undergoing a complex clean-up andreplanting to restore it.

Preventing the Introduction of Invasive SpeciesOntario is home to many species of hardwood trees, including thesugar maple. These trees have evolved for thousands of years andadapted to life in this region. The Asian long-horned beetle, aspecies native to China, was first detected in North Americanforests in 1996 (Figure 3.11). It may have arrived in woodenpacking crates used to deliver goods from Asia. These beetles arenow a serious threat to hardwood tree species in Ontario.

Various levels of government are involved in preventing thespread of the Asian long-horned beetle. For example, the City ofToronto is trying to stop further spread of the beetle byestablishing by-laws against moving firewood and other woodproducts that may contain the beetle (Figure 3.12).


Figure 3.10 Because plants take time to grow, habitat restoration often takes many yearsto complete.

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According to some estimates,species are going extinct at a rateof 1 every 20 minutes. Datacollected by ecologists arecombined with models to calculatethis average rate. The model helpsestimate how many species arecurrently on the verge of extinction.Go to ScienceSource to find outmore about the model.

Take It Further

Also, Agriculture Canada, a branch of the federal government,has strict laws against citizens or visitors bringing foreign food,animals, or plants into the country. This helps prevent peoplefrom unwittingly introducing foreign organisms into Canada’secosystems (Figure 3.13).


Figure 3.11 The Asian long-hornedbeetle was first discovered in Toronto andVaughn in 2003.

Figure 3.12 The City of Toronto, the Municipalityof Vaughn, and Agriculture Canada are workingtogether to prevent the spread of the beetle.

Figure 3.13 This sniffer dog at Pearson International Airport is trained to detect food andplants in luggage.

Learning Checkpoint

1. List four ways in which governments can help sustain biodiversity.

2. (a) How does the establishment of protected areas help sustainbiodiversity?

(b) What are three types of protected areas used by governments to do this?

3. What is a remedial action plan? Give an example of such a plan.

4. What organism currently threatens Ontario hardwood species, and whatgovernment actions are being used to slow its spread?

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Decision-Making Analysis

IssueRecycling programs divert wastes from landfills.Recycling was practically unknown only a generationago. Now, all municipalities in Ontario participate insome form of recycling program. It is not without itsdifficulties, and making it possible to connecteveryone into a recycling network is still a major goal.

Background InformationGarbage disposal is a major issue for manymunicipalities across Ontario because the use oflandfills only is not a sustainable approach. Landfillshave a tendency to fill up. Building new landfills isexpensive, and local residents are usually reluctantto have them near their property. Chemicals can leakout of an improperly constructed landfill. Heavymetal contamination from old batteries andelectronics is just one example.

Blue and grey boxes, green bins, and yard wastecomposting programs have generally beensuccessful in Ontario (Figure 3.14). For example, inthe City of Toronto, 42 percent of residential waste isredirected from landfills through recycling programs.However, apartment dwellers recycle only 13 percentof their garbage.

Suppose that you have been hired by your localcouncil to create an action plan to increaseparticipation in the local recycling program. Thecouncil wants you to find out which groups cannot orwill not participate in the current recycling program.

They also want you to suggest ways to increaseparticipation. Be aware that some members of thecouncil do not see the benefits of recycling. In order tomake the case for expanding the recycling program,you have to outline the benefits to them as well.


1. ScienceSource On the Internet, find informationabout the diversion of solid waste from landfills.Also look in print materials for information on wastediversion from landfills.

2. Research your local recycling program. Findbrochures, fact sheets, and newspaper articlesto answer the questions below.

• Who can participate in the program?Businesses, single-family dwellings,apartment buildings? People in rural areas?

• How does it work? Is there curbside pickup,or do residents have to take their recyclingto a depot?

• Is it difficult for some groups to participate?If so, which groups, and why?

3. Use your research to develop a plan that couldimprove current recycling efforts for the groupsyou have identified that have troubleparticipating.

4. Web 2.0 Develop your findings about recyclingfor the local council in the form of a Wiki, apresentation, a video, or a podcast. Make sure tooutline your action plan to improve participationin the recycling program.

Skill Practice

5. Prepare a five-point summary specificallydesigned to explain the benefits of recycling tosomeone who may not think recycling isworthwhile.

SKILLS YOU WILL USE� Identifying and locating

research sources� Thinking critically and logically

Assessing a Government Program — Recycling

A20 Skills Reference 4

Figure 3.14 Some municipalities do not have curbside pickupfor recycling.

Key ActivityDI

STSE

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Key Concept Review1. What is the role of conservation biology in

ecosystem management?

2. List four levels of classification of at-riskorganisms, and explain the meaning of each.

3. Give an example for both in-situconservation and ex-situ conservation.

4. What is the difference between extirpatedand extinct?

5. List two approaches that the Convention onBiological Diversity uses to help conservespecies.

6. What are two major roles for zoos?

7. What are the advantages of protecting aspecies without removing it from its naturalhabitat?

8. How does the Ontario Endangered SpeciesAct work to protect at-risk species?

Connect Your Understanding9. Why is it important for there to be an

agreement between Canada and the UnitedStates to help rehabilitate the Great Lakes?

10. Suppose the Canadian government hasdecided to create more national parks. Youhave been asked to decide which placesshould be considered as potential sites forparks. How would the concept ofbiodiversity hot spots help you makedecisions?

11. How has the rehabilitation of the Great Lakeshelped to ensure ecological sustainability?

12. Propose a course of action to successfullyreintroduce the Karner blue butterfly to themeadows near Peterborough.

13. The grey fox, pictured in the photograph, isthreatened in Canada. It is estimated thatthere are at least several thousand breedingpairs. Would in-situ or ex-situ methods bemost appropriate to protect this species?Explain.

14. Canadian border officials allow a family tobring a box of grapefruit home to Canadafrom their trip to Florida. However, UnitedStates border officials confiscate a box ofgrapefruit that another family wishes tobring with them on their trip to the U.S.Propose a reason for the different responsesto the grapefruit by U.S. and Canadianofficials.

Reflection15. This section identified different actions that

governments can take to ensure thesustainability of ecosystems. Which of theactions interested you the most? Why?

16. How can you, as an individual, have animpact on the way your municipal,provincial, or national government takescare of ecosystems?




Question 13

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The Toronto Evergreen Brick WorksWhat happens when you combine leading-edge technologies insustainability, support for local food producers, use of abandonedheritage buildings, and a way to connect a city community withits own local ecosystem? In Toronto, the result is Evergreen BrickWorks, an urban restoration project (Figure 3.15).

The Brick Works was originally built in 1889 on a flood plainin the Don River Valley, in the heart of the city. The factoryproduced many of the bricks used in many of Toronto’s buildings,as well as buildings across Ontario and Canada.

As the city grew, the Don Valley was spared from developmentbecause the river flooded occasionally. This helped keep the areaavailable as parkland. The Brick Works closed in the 1980s, andthe buildings were abandoned.

Today, these abandoned buildings are being transformed intoa national centre for environmental education. The centre willoffer programs on how to integrate sustainability into daily living.One of the first projects to open was a farmers market. Everyweekend, it is filled with shoppers (Figure 3.16). The marketsupports local producers and connects consumers withhigh-quality, locally produced food.



• Ecological footprints showindividuals, groups, or nationshow much land is needed toproduce what they consumeand absorb their wastes.

• Environmental stewardshipmeans taking care of resourcesin a sustainable way.

• Organizations and individualsare taking action to make surewe use resources in asustainable way.

Environmental Stewardship

Figure 3.15 An artist’s rendition of the restored Brick Works, once it is completed.

3.2

Figure 3.16 The Brick Worksfarmers market opened in 2007and has been a great success.

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Restore, Reduce, RenewThe restoration plan for one of the buildings includes manymeasures to reduce the building’s environmental impact. Itincorporates a vertical garden or “living wall” to help moderate thebuilding’s temperature. To reduce the need for heating and cooling,a series of movable panels on the exterior walls shade the building insummer and help to warm the building in winter. Large-scale artinstallations can be attached to the panels.

The Don River is also being restored to make its banks moresuitable for native species to thrive. In this way, both the landsand the buildings are undergoing renewal. Evergreen Brick Worksis one of many examples of how environmental stewardshipcontinues to take hold in our society (Figure 3.17).


A21 Quick Lab

Making Connections

“Environmental stewardship” is a term that relatesmany ideas that you have studied in this unit. In thisactivity, you will have an opportunity to recall themeanings of some of these ideas and will practiseconnecting them in sentences.

PurposeTo make connections between concepts related toenvironmental stewardship

Procedure

1. Pick a partner.

2. To start, one partner rolls the die three times. Thefirst roll of the die corresponds to a Society factorlisted below, the second corresponds to an

Environment factor, and the third corresponds toan Impact factor. For example, if the first roll is 4,then the factor is “regulations.”

3. The roller now creates one to three sentencesthat connect the three terms together.

4. While the first roller writes, the other partner doessteps 2 and 3.

5. Repeat as many times as time permits.

Questions

6. Share with your class the best sentence that you cameup with, and explain why you think it worked so well.

7. List any combinations of words that did not workwell together, and suggest a reason why this wasthe case.

8. Think of one new word for each category, andwrite a sentence connecting the new words.

Materials & Equipment• 1 six-sided die

Figure 3.17 Evergreen Brick Workssite in the Don Valley

Society Environment Impact1 Conservation 1 Nutrients 1 Overexploitation

2 Culture 2 Water 2 Habitat change

3 Politics 3 Air 3 Invasive species

4 Regulations 4 Soil 4 Pollution

5 Consumption 5 Habitat 5 Climate change

6 Recycle 6 Energy 6 Technology

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Ecological FootprintAn ecological footprint is an estimate of how much land andwater is needed to support your lifestyle (Figure 3.18). Thisincludes all the land and water needed to produce the resourcesyou consume as well as absorb all the wastes you produce. Thewastes include all the emissions produced in manufacturing theproducts you consume. All the things that ecosystems provide arealso considered to be a part of your ecological footprint, includingproviding fresh water and decomposers that recycle wastes.

The average Canadian requires 8.9 ha to maintain his or herlifestyle. This is equivalent to about 17 football fields. If everyoneon Earth had the same ecological footprint as a typical Canadian,we would need 5.7 Earths! The size of people’s ecologicalfootprints varies widely throughout the world (Table 3.2).

An ecological footprint is a tool that can be used to determinehow much resources a person, an organization, or even an entirecountry consumes. Once we know our ecological footprints,individuals, organizations, and countries can then know to whatextent they need to engage in more sustainable activities. ManyCanadian municipalities are now using ecological footprints tomeasure their progress towards sustainability. A large number ofenvironmental stewardship programs also calculate ecologicalfootprints in order to evaluate their progress. An ecologicalfootprint can be calculated for a person, a building, a nation, or awhole continent.


Figure 3.18 A person’s ecological footprint includes the space needed for extracting energy,living and working, manufacturing and waste disposal, growing food, and extracting resources(timber, pulp and paper, textiles).


CountryFootprint(ha/person)

India 0.86

Pakistan 0.64

Japan 4.77

United States 9.57

Table 3.2 Some Other Nations’Footprints

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Scientists are concerned that as populations increase andconsumption of resources also increases, at some point, theworld’s ecological footprint will eventually equal all the availableland and water on Earth. A number of estimates now suggest thatwe reached that point in 1990. From that time on, we have beenconsuming Earth’s resources faster than the planet can regeneratethem. We live in a unique and risky period where we consumemore than Earth can produce. We have to change the way we useEarth’s resources.

Environmental StewardshipA good steward is someone who manages any sort of resourcewisely. Being an environmental steward means taking care ofour natural resources to ensure that they are used in sustainableways for current and future generations. Stewardship includesactivities such as reducing the amount of resources we use, reusingitems instead of throwing them away, and recycling used items. Italso includes conserving existing ecosystems and restoringdamaged ones. To be successful, environmental stewardshiprequires governments, organizations, and communities to work toprevent or reduce threats to ecosystems.

Sustainable Agriculture In the 1980s, a group of Ontario farmers were worried about theeffects that some farming methods were having on theenvironment. For example, some were concerned about the effectsthat fertilizers were having on water quality. Others wereconcerned that their tilling methods were causing soil erosion.Together, they developed plans to address problems related topollution from farms. With the assistance of the federalgovernment and agriculture organizations, they developed aprogram called the Environmental Farm Plan (EFP). The EFP is atool that farmers can use to identify environmental problems ontheir farms and develop action plans to address these problems(Figure 3.19).

For example, pesticides can have many negative effects onecosystems. In the 20 years since the EFP started, pesticide usehas been reduced by 50 percent on Ontario farms. EFPs are nowbeing used on farms across Canada.

Environmental farm plans can include actions such as usingintegrated pest management, which is a method of pest control


Figure 3.19 Environmental FarmPlans have become a useful tool forOntario farmers.


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that uses knowledge about a pest’s biology and habitats. Thetechnique is to choose the best combination of common-sensemethods to keep the pest population under control, rather thanusing pesticides to totally eradicate them. For example, rotatingdifferent crops in the same field each year can be used to controlpests that only eat one of the two crops. If the pest has nothing tofeed on, its population drops. Reducing pesticide use helps thesurrounding ecosystems and it also reduces risks to humanhealth.

Soil Conservation and Organic FarmingSoil is a limited resource. It takes hundreds of years to form,but it can be blown or washed away very easily. Soilconservation means using farming methods that protect thesoil from erosion and loss of nutrients. No-till farming is amethod of planting and growing crops from year to year thatdoes not disturb the soil (Figure 3.20). This means leaving thestubble and roots of last year’s crop in the soil. The roots holdthe soil and prevent erosion. The next year’s crop is plantedamong the stubble. However, not all crops can be grown usingno-till farming.

Some farmers use organic farming. On organic farms,farmers do not use chemical fertilizers or pesticides. This helps toreduce water pollution. However, organic farms may not be ableto produce the same amount of food as a non-organic farm.


Figure 3.20 A new crop of soybeans is growing among the stubble of last year’s corn cropin a no-till field.

Organizing forWriting

Once your research is complete,begin to organize your notes.Create headings for majorsubtopics, and gather yournotes under each heading. Ifyou use sticky notes to recordyour research points, then youcan arrange and rearrange themunder the appropriate headingsto create maximum impact.

During Writing

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Figure 3.21 The Niagara regionproduces many fruits such aspeaches, apples, and plums.

Eating Locally Produced FoodsYour lunch may have contained oranges from South Africa orapples from New Zealand. Before modern refrigeration processesand efficient transportation networks, most foods were consumedclose to where they were produced. We have benefited from beingable to move foods great distances very quickly. We can now eatfresh fruit and vegetables in the middle of winter.

Currently, in North America, many foods are grown andprocessed on a very large scale. It is very efficient, but it can leadto problems. Most food items, including fruits and vegetables, arepackaged or processed in large, centralized processing plants andthen shipped all over the continent. If food spoilage orcontamination is found in one of these centralized plants, foodthat has already been distributed has to be recalled and removedfrom supermarket shelves all over North America. This is costlyand time-consuming. Decentralized food production can helpreduce this problem. Also, the amount of energy needed to bringCalifornia-grown strawberries to Ontario is much greater thanthe amount needed to bring Ontario-grown strawberries to a localfarmers market.

Sustainable agriculture and eating locally produced foods, ifthey are available, are connected. Buying locally produced foodsupports local farmers. If these farmers get enough income fromtheir farms, they will continue to use their land for agriculturerather than selling their land to be developed for housing or otherpurposes. Locally grown produce tends to be fresher because ithas been picked more recently than produce grown in Californiaor other distant areas (Figure 3.21). In season, you might be ableto eat corn that was picked less than 24 hours before. Even whenmore food is sustainably produced, some foods will have to betransported long distances, especially in Ontario, where ourgrowing seasons are relatively short.


Learning Checkpoint

1. What is meant by the term “ecological footprint”?

2. What do calculations of the total ecological footprint of all of humanity sayabout our current use of Earth’s resources?

3. What does it mean to be an environmental steward?

4. What is an Environmental Farm Plan?

5. How is soil conservation related to sustainable agriculture?

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Figure 3.22 The FSC’s tree checklogo identifies products as beingproduced from wood from sustainablymanaged forests.

Sustainable ForestryThe Forest Stewardship Council of Canada (FSC) is anon-governmental organization, or NGO. This means it operatesindependently of any government. The FSC originated in Ontariobut now operates around the world. This organization setsstandards for sustainable forest management and certifies forestsand forestry practices that meet their standards. For a forestrypractice to be certified:

• Waterways and wildlife habitat have to be protected.

• Parts of the forest have to be preserved.

• The cut areas have to be replanted.

• The cut areas cannot be replanted with just a singlespecies. The forest must be able to achieve a wild state.

The FSC also provides a way for consumers to know whetherthe wood or wood product they are planning to buy has beenmade without endangering an ecosystem. For example, someonewho wants to buy a wooden bench can look for an FSC symbol onthe product (Figure 3.22). The symbol indicates that the woodwas obtained in a responsible manner.

There are different sustainable management standards fordifferent types of forests and different locations. For example,there is one set of standards for national boreal forests and adifferent set of standards for British Columbia’s forests. However,this is taken into account in the certification process, so theconsumer simply has to look for the logo on the product to knowthe appropriate standards were followed.

Urban ForestsIt is easy to think of forests as existing only away from settledareas, but there are urban forests too (Figure 3.23). Like a wildforest, an urban forest includes all the trees and shrubs present aswell as their soils. Healthy urban forests can help communitiesachieve many sustainability goals, such as removing excess carbonfrom the atmosphere. Trees store carbon and continuouslyremove it from the atmosphere. Large trees can remove 50 timesmore carbon than small trees can. They also reduce energyconsumption by providing shade. If urban buildings are shaded,the need for air conditioning is reduced. Less air conditioningmeans less energy consumption.

Urban forests provide many other benefits as well. They helpslow the run-off of water from rainstorms. This reduces the


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pressure on a city’s storm-drain system. Trees protect soils fromerosion and filter chemicals from water and air. Urban forests canactually help repair damaged ecosystems by repairing unhealthyor damaged soils. They also provide habitat for other species, sothey help increase biodiversity. And, of course, trees are alsoenjoyable to look at and be around.

Many cities and municipalities realize the importance ofplanting and maintaining healthy trees on public land. Most haveurban forestry departments. The many trees on private land arevital too. There are many different organizations that educate thepublic about planting trees. For example, Tree Canada is anorganization that promotes planting trees on both public andprivate land. In the last week of April, Arbour Week focusses oneducating the Ontario public about the advantages of planting trees.

Sustainable ConstructionMost people in Canada spend a lot of time in buildings, especiallyin the winter. The thousands of large buildings and millions ofhomes in Canada have a significant effect on the environment.Building them, living in them, and heating and cooling them usesenergy, uses many different resources, and produces manydifferent types of pollution. Sustainable construction methodshelp reduce these impacts.

Just as it is possible to certify a forest as being used in asustainable way, buildings can be certified as being built in asustainable way as well. The Canada Green Building Council usesthe Leadership in Energy and Environmental Design (LEED)


Figure 3.23 Part of Ottawa’s urban forest

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rating system. Libraries, schools, office buildings, and homes canbe scored on how efficiently they reduce water consumption,reduce energy consumption, use renewable energy sources, reuseand restore existing buildings, incorporate daylight, and manyother factors (Figure 3.24).

Businesses and Sustainability Many businesses are responding to consumers’ demands toimprove their business practices by promoting sustainability andreducing their footprints (Figure 3.25). Many manufacturers ofcleaning products are introducing “green” cleaning products thatdo not have phosphates and other substances that causeeutrophication or degrade ecosystems in other ways. Manymanufacturers have their products certified by independentecological certifying organizations, such as EcoLogo.

Two Canadian businesses are taking sustainability seriously.Bullfrog Power is an Ontario company that sells environmentallyfriendly electricity produced from renewable sources such aswind turbines and low-impact hydroelectric projects. Thesesources produce no emissions and so do not contribute to climatechange or acid rain. Bullfrog’s electricity costs slightly more thanconventionally produced electricity, but many businesses,government agencies, and homeowners buy their power fromBullfrog. The company that produces Boomerang paints takesrecycling seriously. It takes leftover paint from recycling centres,sorts the leftovers by colour, and blends similar shades into newpaint shades. The leftover paint cans are melted down and


Figure 3.24 (a) The École secondaire jeunes sans frontières building in Brampton is a LEED-certified building. It has a green roof, energy-efficient windows, and water-efficient plumbing, and 91 percent of the construction waste was recycled or reused on other projects. (b) LEED statistics on the building.

The Canadian Federation ofMunicipalities has conducted asurvey of ecological footprints oflarge municipalities acrossCanada. How does your city or acity near you compare with therest of the country? Begin yourresearch at ScienceSource.

Take It Further

(a) (b)

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reshaped into new paint cans. The reclaimed paint is then sold inthe recycled cans. By reusing paint and recycling cans, theyreduce the amount of waste going to landfills and use no newresources to make the paint.

Individuals and SustainabilityTable 3.3 lists actions individuals can take to use resources in amore sustainable way. You and your family may have alreadystarted to do many of these things.


Figure 3.25 (a) Clorox has introduced cleaners that use more environmentally friendly ingredients. (b) EcoLogo has been certifying productsas environmentally friendly for over 20 years. (c) Boomerang paints are reused paint and recycled paint cans.

Action Consequence

Reduce emissions. • Riding your bike, taking public transit, and using fuel-efficient vehicles are all ways toreduce carbon emissions.

Save energy. • Lowering the thermostat, unplugging small appliances, and installing compact fluorescentlight bulbs all reduce the demand for electricity, which is often generated by burning fossilfuels.

• Reducing electricity consumption indirectly reduces air pollution.

Eat food produced locally. • Buying food from local farmers reduces pollution from the trucks used to transport theproduce. Buying from local organic farmers reduces pollution from pesticides as well.

Plant wisely. • Planting native plants reduces the chance of introducing an invasive species. • Planting drought-tolerant plants reduces water usage in summer.

Buy wisely. • Buying only what you really need reduces waste and reduces pressure on ecosystems. • Think about the impact that using and disposing of the item will have on the environment.• Choose products that have the EcoLogo or that you know were made in an

environmentally responsible way.

Get involved. • Check out your school community. Does it have an environmental awareness group? Is afull recycling program in place? If so, check it out. If not, think about organizing one.

• Invite your family and friends to do an ecological footprint assessment.• Check out local or national organizations promoting environmental sustainability.

Table 3.3 Environmentally Sustainable Actions

(a) (b) (c)

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A22

What’s for Dinner?

For many Canadians, a typical dinner maycontain food shipped from all over the world. Asyou walk through your local supermarket, haveyou considered how much of the food is actually“fresh”? For example, the tomatoes you see in theproduce section were probably picked weeks agoin California and shipped thousands of kilometresby truck or airplane before arriving at your localgrocery store.

1. Would you consider changing what you eatin order to eat more locally grown food? Howdifficult would it be?

2. If you did eat more locally grown food, whatchanges would you have to make to yourdiet during the winter?

3. If you did eat more locally grown food in thesummertime, what changes would you haveto make to your diet?


Learning Checkpoint

1. How does the Forest Stewardship Council help make it possible forconsumers to make environmentally responsible decisions regarding thepurchase of wood products?

2. What is meant by the acronym “NGO” with respect to community groups?

3. List four standards that any forestry practice must meet to receive ForestStewardship Council certification.

4. What are three ways in which an urban forest can benefit a community?

5. What are three ecological benefits that result from using sustainablebuilding construction methods?

6. Identify one environmentally sustainable action that an individual can do,and give one or two positive consequences of this action.

Figure 3.26 The produce section of the supermarket hasitems from many countries.

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A23 Quick Lab

PurposeTo determine the size of your ecological footprint anddetermine if your lifestyle is sustainable

Procedure

1. Use the ecological footprint calculator yourteacher provides to calculate your ecologicalfootprint.

2. Record or print out the relevant information.

Questions

3. How does your footprint compare to the averageCanadian’s footprint? Give reasons for why yoursis higher or lower than average.

4. How does your footprint compare to that of anaverage person living in China (1.4 ha/person)?

5. Is the ecological footprint of China greater or lessthan the ecological footprint of Canada? Explain.

6. What factors cause the average Canadianfootprint to be so much larger than those in thedeveloping world (Nigeria: 1.2 ha/person; Brazil:2.2 ha/person)?

7. List three things that you could do to reduceyour ecological footprint.

Calculating Your Ecological Footprint

A24 Quick Lab

PurposeThere are many environmental organizations inOntario and Canada. What are some of theseorganizations doing to sustain ecosystems?

Procedure

1. ScienceSource Use the Internet to research oneof the following environmental organizations oranother approved by your teacher:

2. Find out what types of projects your organizationis doing in Ontario or across Canada.

Questions

3. What kinds of environmental problem(s) doesthe organization attempt to improve?

4. How does the organization promote sustainableuse of ecosystems?

5. Do you think the organization’s projects areeffective? In what ways do you think they couldbe more effective?

6. Write a short summary of your findings, andpresent it to the class.

Environmental Organizations

Materials & Equipment• computer with Internet access

Materials & Equipment• computer with Internet access

• World Wildlife Fund

• Pollution Probe

• Ducks Unlimited

• Greenbelt ofOntario

• Nature Conservancy ofCanada

• The Sierra Club ofCanada

• The Suzuki Foundation

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Key Concept Review1. How does the idea of an ecological footprint

help an individual determine whether he orshe is living in a sustainable fashion?

2. The ecological footprint of all of humanityhas been calculated to be equivalent to1.3 Earths. What does this mean?

3. How do Environmental Farm Plans helpOntario farmers?

4. What two technological developmentscontributed to the ability to ship foodproducts very long distances?

5. What is organic farming?

6. How can shopping locally promote theconservation of farmland?

7. How do good soil conservation practicesreduce soil erosion?

8. How do forests act like air conditioners tocool a region during hot spells?

9. List five ways that urban forests benefiturban ecosystems.

10. What percentage of Canada’s contributionto excess carbon in the atmosphere comesfrom office buildings and homes?

11. List three ways that individuals can helpreduce emissions from transportation.

Connect Your Understanding12. The Evergreen Brick Works project

embodies the ideas of “restore, reduce, andrenew.” Give one example of how each ofthese terms is put into action at the BrickWorks.

13. An owner of a plant nursery finds aphids, asmall insect pest, on some of her plants. Shedecides to introduce ladybugs to eat theaphids.

(a) Name the strategy she is using tocontrol the pest.

(b) Explain the benefits of this strategy.

14. What is the meaning of the symbol shownbelow, and how might you make use of it?

15. Eco-labels help consumers by demonstratingto them that the producer of a product hasoperated in a sustainable fashion. Meetingthe certification standards can mean a lot ofextra work for a producer. Yet manyproducers strongly support the use ofeco-labels. Suggest four ways that eco-labelsare a benefit to suppliers.

Reflection16. Will the ideas encountered in this section

affect the way you live? How?

17. If you were determined to make onepersonal lifestyle change that would havethe greatest impact on improvingsustainability in your community, whatwould it be? Explain.



Question 14

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COOL IDEASfrom JAY INGRAM


Panamanian Cowbird PuzzleJay Ingram is an experienced science journalist, author of TheDaily Planet Book of Cool Ideas,and host of the Daily Planet onDiscovery Channel Canada.

Figure 3.27The giant cowbird isnative to Panama.

Back in the 1960s, a biologist named Neil GriffithSmith, working in Panama, could not understandthe behaviour of cowbirds (Figure 3.27). A cowbirdis a nest parasite: a female lays an egg in anotherbird’s nest, and the host bird raises the foreignchick along with its own chicks. Usually, femalecowbirds have to be stealthy or else the host birdwill recognize the cowbird’s egg and remove it fromthe nest. But in Panama, cowbirds behaved in twodifferent ways. Some cowbirds behaved normally:a female would hide until the host bird left thenest and then lay one or two eggs that lookedalmost exactly like the host bird’s eggs. Othercowbirds were strangely obvious. In this situation,a cowbird would sit next to a nest in plain view ofthe host bird. When the host bird flew off, thecowbird would sit on the nest and lay an obviouslyforeign-looking egg among the host bird’s eggs(Figure 3.28). But why did the mother bird notjust get rid of that egg when she returned?

Smith discovered that it was all about botfliesand bees. Botflies lay their eggs on newly hatchedchicks, and the larvae feed on the chicks. Chicksinfested with botfly larvae died. But they did notdie if a cowbird chick shared the nest with them.The cowbird chick would eat the botfly larvae,thus protecting the other chicks. Of course, therewas a price for this service: the cowbird chick took

up most of the nest and ate most of the food. Oneor two deprived chicks would die as a result, butnot all of them. In this situation, host adult birdstolerated the presence of a cowbird (Figure 3.29).

However, if the nest was near a beehive, it wasa different story. The bees kept the botflies away.With a smaller fly population, chicks were lesslikely to be infested with larvae. In this case, therewas no advantage to having a cowbird chick in thenest. Female cowbirds had to be much stealthieror their eggs would be removed by the host bird.

Question

1. A cowbird has different strategies for layingeggs in a host’s nest. Explain what eachstrategy is and when a cowbird would useeach one.

Figure 3.28 In this case,the cowbird’s egg looksvery different from thehost bird’s eggs.

Figure 3.29 Cowbirds often lay eggsin the nests of crested oropendolas.

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Key Concept Review1. What is the risk level classification for a

species that is at risk of becomingendangered if limiting factors are notreversed?

2. (a) What is the difference between ex-situand in-situ methods of conservation?

(b) Which is considered a method of lastresort?

3. How can botanical gardens play a role inthe conservation of some species?

4. What is often the single most importantfactor determining the success or failure ofthe in-situ protection of a particularspecies?

5. What law helps to protect theapproximately 200 species at risk inOntario?

6. What is the main ecological purpose ofestablishing provincial parks, nationalparks, wildlife reserves, and marinesanctuaries?

7. What are “biodiversity hot spots”? How areconservation biologists working to protectthem?

8. What major Ontario industry is threatenedby the Asian long-horned beetle, and whatmeasures are being taken to limit thebeetle’s spread?

9. The amount of biologically productive landand water area on Earth is about 6 ha per person.

(a) Currently, the average American usesabout 10 ha per person. What does thismean about consumption by the averageAmerican compared to the availabilityof resources on Earth?

(b) How do Canadians compare toAmericans in terms of averageconsumption per person?

(c) Do Canadians, on average, live withinEarth’s ability to supply resources forgenerations to come?

10. What is the term that relates to taking careof our natural resources to ensure they areused in sustainable ways for futuregenerations?

11. The image below shows a typical farmersmarket that sells local produce. What arethree ecological benefits from buying locallyproduced foods?

12. Name three different actions individualscan take that lead to sustainable use ofresources, and explain how these actionshelp the environment. k

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tk

3 CHAPTER REVIEW

Question 11

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Connect Your Understanding13. Explain how the restoration of Lake Erie is

an example of effective collective action.

14. Suggest ways that governments couldencourage sustainable building constructionpractices.

15. The bird’s-foot violet shown below isendangered because of habitat loss due tofarming. It often thrives in areas that havehad a forest fire, but such fires are limitedby humans. Suggest a method of protectingthis plant other than banning farming orpermitting wildfires.

16. Sometimes, a forestry company will log anarea and replant the entire area with asingle tree species. Would this company becertified as using sustainable practices?Explain why or why not.

17. Suppose you have been hired by a treeplanting organization to promote treeplanting by individuals. Create a brochureto educate homeowners about the benefitsof planting trees on their land.

18. Create a concept map that shows howgovernment, group, and individual actionspromote environmental sustainability.

19. The average Canadian’s ecological footprintis 8.9 ha of land. If this land area weremultiplied by the total number of people inthe world, would it be greater or less thanthe total area of the planet?

20. Certification programs are effective ways todemonstrate sustainable use of resources.However, some certification programs havebeen criticized as being ineffective. Whatmight make a certification programineffective?

Reflection21. Given that humanity is consuming

resources faster than Earth can producethem, how will you take action to create asustainable future? Write a short paragraphoutlining the action you will take. c

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Share your summary of information about anenvironmental organization with a classmate whowrote about a different organization. Listen to areading of your classmate’s article. What was themost important information you heard? What wasnice to know but not entirely necessary?Reconsider your own summary with the samequestions. Write a statement to express what youhave learned about researching and taking notes.

After Writing

Unit Task Link

In the Unit Task, you will be designing asustainable community with a small ecologicalfootprint. Reflect on the examples of government,group, and individual actions to promotesustainability. How have groups and individualsworked together to take action to promotesustainable communities?

Question 15

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• Abiotic and biotic characteristics

• Photosynthesis and cellularrespiration

• Nutrient cycles and energy flows

• Equilibrium and carrying capacity

• The biodiversity on Earth is found in the biosphere, which includes thelithosphere, atmosphere, and hydrosphere. All of these spheres interact. (1.1)

• Energy in ecosystems comes from the Sun. It is transformed into chemical energyby plants. As energy travels along food chains, the amount of usable energydecreases. (1.2)

• Matter is recycled in ecosystems. Plants use matter from the soil and air to maketheir tissues. Matter then passes along food chains, which are the biotic parts ofecosystems. (1.2)

• Decomposers release the substances in organic matter back into the soil, and thesubstances are reused by plants. (1.2)

• Abiotic and biotic factors affect the size of populations in ecosystems. (1.2)

• A population’s carrying capacity is the maximum number of animals that thehabitat can support over a long period. (1.3)

• When a population is at carrying capacity, it is at equilibrium. The number ofbirths equals the number of deaths, and the population is steady. (1.3)

• Factors affecting biodiversity

• Soil profile and soil types

• Factors affecting water quality

• Bioaccumulation andbiomagnification

• Biodiversity includes species diversity, genetic diversity, and ecosystem diversity.(2.1)

• Overexploitation, habitat destruction, pollution, invasive species, and climatechange are factors that decrease biodiversity. (2.1)

• Soil is made up of humus, rock particles, and living organisms. Soil can be clay,sandy or loam, and it can vary in acidity. (2.2)

• Water’s quality is assessed by its oxygen levels and acidity as well as by thepresence of heavy metals, nitrogen, phosphorus, and pesticides. Poor water qualityaffects organisms that depend on the water. (2.2)


AU N I T

SummaryKEY CONCEPTS CHAPTER SUMMARY

• Conserving biodiversity

• Conservation strategies

• Environmental stewardship andsustainable use

• Extinction means the loss of biodiversity. Ex-situ and in-situ conservationstrategies work to protect at-risk species. (3.1)

• Governments use legislation to enact programs to protect ecosystems. (3.1)

• Ecological footprints are a way of representing our resource use. (3.2)

• Environmental stewardship means using resources in a sustainable way. Groupsand individuals are taking action to increase sustainable use. (3.2)

Ecosystems are complex, self-regulating systems of organisms and their abiotic environments.

1

Human activity affects the sustainability of ecosystems.

Governments, groups, and individuals work together to promote sustainable ecosystems.

2

3

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121UNIT A Summary

VOCABULARY KEY VISUALS

CO2 in atmosphere

fossil fuels

carbon compoundsin water

plants

burning offossil fuelsand wood

phytoplankton

primaryconsumers

higher-levelconsumers

decomposers

photosynthesis

photosynthesis

dead organisms

cellularrespiration

water

producers

zooplankton

small fish

large fish

fish-eating birds magnification of chemical’s concentration

1

1000

10 000

100 000

1 000 000

10 000 000

Ecological footprint

Carbon cycle

Biomagnification

• abiotic (p. 13)• aquifer (p. 25)• atmosphere (p. 19)• biodiversity (p. 9)• biome (p. 16)• biosphere (p. 18)• biotic (p. 13)• boreal forest (p. 17)• carnivores (p. 30)• cellular respiration (p. 29)• chlorophyll (p. 28)• community (p. 14)• components (p. 11)• consumers (p. 30)• decomposers (p. 30)• denitrifying bacteria (p. 26)• detritivores (p. 30)

• ecology (p. 12)• ecosystem (p. 13)• elements (p. 24)• environment (p. 8)• freshwater (p. 17)• grasslands (p. 17)• habitat (p. 14)• herbivores (p. 30)• hydrosphere (p. 19)• lithosphere (p. 19)• marine (p. 17)• niche (p. 14)• nitrifying bacteria (p. 26)• nitrogen fixation (p. 25)• nutrient (p. 22)• nutrient cycle (p. 24)• omnivores (p. 30)

• organic matter (p. 30)• photosynthesis (p. 28)• population (p. 14)• primary consumers (p. 30)• producers (p. 30)• reservoir (p. 24)• scavengers (p. 30)• secondary consumers

(p. 30)• species (p. 14)• stewardship (p. 8)• sustainability (p. 9)• system (p. 11)• temperate coniferous

forest (p. 17)• tertiary consumers (p. 30)• tundra (p. 17)

• acid rain (p. 70)• acidity (p. 74)• bedrock (p. 72)• bioaccumulation (p. 79)• biological oxygen

demand (p. 77)• biomagnification (p. 79)• clay soil (p. 73)• clearcutting (p. 62)• climate (p. 60)• climate change (p. 60)• crop rotation (p. 75)• dissolved oxygen (p. 77)

• eutrophication (p. 78)• extinction (p. 54)• genetic diversity (p. 54)• global warming (p. 60)• habitat change (p. 55)• habitat fragmentation

(p. 56)• heavy metals (p. 79)• invasive species (p. 59)• loam soil (p. 73)• native species (p. 55)• non-point source

pollution (p. 58)

• overexploitation (p. 56)• pesticides (p. 80)• point source pollution

(p. 58)• pollution (p. 58)• sandy soil (p. 73)• soil (p. 72)• soil erosion (p. 74)• subsoil (p. 72)• sustainable use (p. 54)• topsoil (p. 72)• urban sprawl (p. 62)

• at risk (p. 94)• conservation biology

(p. 94)• ecological footprint

(p. 106)• endangered (p. 94)

• environmental steward (p. 107)

• ex-situ conservation (p. 96)

• extirpated (p. 94)• in-situ conservation

(p. 96)

• integrated pestmanagement (p. 107)

• organic farming (p. 108)• soil conservation (p. 108)• special concern (p. 94)• threatened (p. 94)

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AU N I T

Task


Building a Sustainable Community

Getting StartedChanging your light bulbs and being moreconscientious about recycling are two simple ways tomove towards a more sustainable lifestyle. Imagine ifyour entire community adopted such practices as a wayof life. There are communities that do. They even havea name: eco-villages. Eco-villages are completelyself-sufficient, sustainable communities designed tohave a minimal footprint on surrounding ecosystems.Eco-villagers carefully control their fuel and foodconsumption. Eco-villagers try to live, work, and play ina small region to minimize commuting, which reducesenergy consumption. Walking a short distance to workor school can be a lot more satisfying than spendinghours a day in traffic.

Your GoalThe project has three parts.

• First, you will investigate in what ways certainaspects of your local community may beecologically unsustainable.

• Then, you will research changes that can bemade to make some of these aspects moresustainable.

• Finally, you will use your research to design acompletely sustainable community for your area.

What You Need to KnowMost eco-villages share several key characteristics,including the following:

• use of renewable energy sources

• agriculture that is closely related to natural localconditions

• homes built using techniques and materials thathave a minimal impact on the environment

• homes that have the capacity to provide power,water, and sewage solutions without relying on acentralized system

A green-roofed cabin in Findhorn, an eco-village in Scotland.

Criteria for SuccessYou will work effectively and co-operatively as part ofa team designing a new eco-village. You will assumea specific role on the team, such as:

• builder

• food specialist

• technologist

• water manager

• waste supervisor

• restoration specialist

You will research aspects of the eco-village relating toyour area of research and collaborate with the otherteam members to design the village.

For the area of expertise you select to research, youmust:

• outline the ways the current situation isunsustainable

• outline specific changes that will increase thesustainable use of local ecosystem resources

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123UNIT A Task

What You Need

• computer with Internet access

Procedure

1. In your group, brainstorm aspects of your localcommunity that are unsustainable. Organize yourthoughts into the following categories: buildings,food, technology, water, waste, and restoration.Brainstorm possible problems with:

• current building design and constructiontechniques

• current food production and consumptionpatterns

• energy demand at global, national, and locallevels

• local water sources and how much people usefor such things as irrigation, washing, and foodpreparation

• how well your community reduces, reuses, andrecycles

• local ecological issues such as habitat changeor fragmentation or pollution

2. Decide which expert role each person will assume.Use the results of the group brainstorming that relateto your field of expertise to start a graphic organizer.

3. ScienceSource On the Internet, find informationrelated to the aspect of sustainable communitiesyou are researching. Look for terms such as “eco-village,” “sustainable community,” and“permaculture” in your search.

4. As a group, decide on the best location for youreco-village. Keep in mind that your village must beas self-sufficient as possible. Your location shouldhave ready access to building materials, water,places of employment, and schools.

5. Collaborate with your team to design an eco-villagethat incorporates some of each expert’s ideas.

6. Decide how to present your design ideas. Will youcreate a pamphlet, a PowerPoint presentation, aposter, a Web page, or use some other method?

7. Present your eco-village design.

Assessing Your Work

8. Do you think building a completely sustainablecommunity is possible? Explain.

9. What were the advantages and disadvantages ofhaving a group of experts create the eco-villagedesign?

Beddington Zero Energy Development is an eco-village in London,England. Its homes use 10 percent of the energy needed to heatsimilar-sized conventional homes. This eco-village vegetable garden makes use of existing materials.

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UNIT A Review

Key Terms Review1. Create a concept map that illustrates your

understanding of the following terms andhow they relate to sustainable ecosystems.

Key Concept Review

Ecosystems are complex, self-regulatingsystems of organisms and their abioticenvironments.

2. Describe an abiotic factor that could affect apopulation of squirrels.

3. How is a food chain related to a food web?

4. Snapping turtles eat frogs, frogs eatgrasshoppers, and grasshoppers eat grass.

(a) Construct a food chain using the aboveorganisms.

(b) Add a decomposer to your diagram.

(c) Add a source of energy for theproducers to your diagram.

5. The nitrogen cycle relies on the actions ofseveral distinct types of bacteria. List anddescribe the function of each.

6. Describe three types of symbioticrelationships, and give an example for eachone.

Human activity affects the sustainabilityof ecosystems.

7. Define the term “genetic diversity.”

8. List five major factors that affectbiodiversity.

9. List the elements that make up soil.

10. Which type of soil would most gardenersprefer to have? Why?

11. What type of measurement can be used todetermine the acidity of the soil?

12. What method can farmers use to restorenutrients in the soil of their fields?

13. Do “dissolved oxygen” and “biologicaloxygen demand” describe the samephenomenon? If not, how are the two termsdifferent?

14. How are modern pesticides animprovement over earlier ones?

Governments, groups, and individualswork to promote sustainableecosystems.

15. Place the following categories in order fromthe least serious to most serious: extirpated,special concern, extinct, endangered,threatened.

16. How can soil erosion be reduced?

17. What is one measure the federalgovernment takes to prevent invasivespecies from being accidentally introducedinto Canada?

18. Name an international treaty that protectsbiodiversity in Canada and around theworld. k

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A Review

• abiotic factors • ecosystem• atmosphere • equilibrium• biodiversity • hydrosphere • biomagnification • limiting factors• biosphere • lithosphere • biotic factors • photosynthesis • carrying capacity • population• cellular respiration • sustainability

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Connect Your Understanding19. Explain why it is more accurate to define

the biosphere as a global ecosystem ratherthan a global community.

20. Hypothesize what would happen to anecosystem that had all of its decomposersremoved.

21. Bacteria are bad for your health and areresponsible for many diseases that hurthumans, animals, and plants. All effortsshould be taken to completely eradicatebacteria on the planet.

(a) Evaluate the validity of this statement.Support your answer.

(b) If necessary, modify the statement tomake it more accurate.

22. Study the following energy pyramids.

(a) Which pyramid best represents asustainable ecosystem?

(b) Explain why each of the other twopyramids is unsustainable.

(c) Suppose data were collected from theecosystem represented by B in 10 years’time. Draw an energy pyramid thatmight describe energy flow in theecosystem at that time. Explain why youdrew it the way you did.

Question 22

23. Examine the graph below.

Question 23

(a) During which years is this population ofminks growing the fastest?

(b) What is the carrying capacity of thepopulation?

(c) What factors cause the population tolevel off rather than continue toincrease?

(d) What may have contributed to thesudden increase in minks?

24. Decide which factor each of the followingscenarios describes.

(a) A new school is built near a forest. Asection of trees is clear-cut, and anearby creek is diverted away from thebuilding area.

(b) Emissions from industry andautomobiles are entering theatmosphere and contributing toincreasing temperatures around theplanet.

(c) Sea otters have the thickest fur of anyanimal. Humans prized their fur formaking coats. Sea otters were huntedalmost to extinction.

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UNIT A Review

25. What activity does the photograph show?

(a) What effects does the activity in thephotograph have on a nearby aquaticecosystem?

(b) What effects might the activity have ona boreal forest ecosystem?

Question 25

26. Many people assume that if water appearsclear, then it is safe to drink. Are they correct?What indicators would you use to determinewhether the water is actually safe?

27. The pond in the photo is located in afarming area. Hypothesize what may haveoccurred in the pond.

Question 27

28. Many pollutants enter an ecosystem in verysmall amounts. If the amounts are so small,how can they harm ecosystems?

29. The black-footed ferret population isincreasing as a result of captive breedingprograms. The ferrets’ main habitat isgrassland. Most of their habitat was turnedinto farmland. The ferrets’ primary sourceof food is prairie dogs, which live in largecolonies. The ferrets also use abandonedprairie dog burrows for shelter. They arevulnerable to sylvatic plague, a disease thatis transmitted by fleas on prairie dogs.Create an in-situ conservation strategy toincrease the ferret population.

30. (a) What changes would you recommend toyour local lumber supplier to reduce itsecological footprint?

(b) If, as a result of following yourrecommendations, the products costmore than similar products in otherstores, would you buy the product fromthis store? Explain why or why not.

31. Suppose your school board wants torenovate your school to improve thebuilding’s LEED rating, and they have hiredyou as an ecological consultant. Create areport that outlines changes you think needto be implemented to increase your school’sLEED rating.

32. A homeowner dislikes the dandelions andchickweed in his front yard. He wants alush, grassy lawn that his children couldplay on and that his neighbours wouldadmire. He decides to use pesticides toeliminate the weeds. Critique his decisionto use pesticides. List the positive andnegative consequences of using pesticides.If you decide that using pesticides is not thebest course of action, propose alternativeactions the homeowner could take. c

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127Unit A Review

Skills Practice

33. The diagram shows the set-up for anexperiment. Water taken from a tank full offish was added to all the test tubes. A smallaquatic plant was placed in test tubes B and D. Carbon dioxide forms carbonic acidwhen it dissolves in water. Phenol red is asubstance that turns yellow in the presenceof carbonic acid. A few drops of phenol redwere added to each test tube. The tableshows the initial observations for theexperiment. Test tubes A and B were placedin a dark, cool location. Test tubes C and Dwere placed in a sunny location.

Question 33

(a) What is the purpose of test tubes Aand C?

(b) Using your knowledge of the carboncycle, predict final water colour for eachtest tube.

(c) Explain your predictions for eachtest tube.

(d) The experiment is repeated, but eachtest tube is filled with cold tap waterinstead of water from a tank full of fish.Predict the initial and final colour of thewater in each test tube.

34. A pitcher plant is a carnivorous plant thattraps insects such as crickets. The insectsdie inside the plant and decompose. Theplant absorbs the nutrients from theirdecomposing bodies that the soil does notcontain. The pitcher plants are consumedby herbivorous mammals. Draw a foodchain that represents this scenario.

35. In a particular ecosystem, it has beendetermined that the secondary consumersuse 5200 kJ/m2 of energy.

(a) How much energy was stored in theproducers in that same food chain?

(b) How much energy would be used by thetertiary consumers?

36. (a) Create a graph that shows thepopulation growth of an invasivespecies that has been recentlyintroduced to a new area.

(b) Why did you draw the graph the wayyou did? Justify your answer. c

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UNIT A Review

37. The following graph shows the populationof a group of caribou on an island. Howwould you explain the changes inpopulation?

Question 37

38. A population of wolves was also introducedto the same island that had the caribou inquestion 37. The following table containswolf population data. Use the graph anddata from the table to develop a hypothesisthat explains the fluctuations in the deerpopulation and the island’s carryingcapacity.

39. Create a graphic organizer that showsdifferent types of pollutants and how theyaffect terrestrial and aquatic ecosystems.

40. The Department of Fisheries and Oceanscollects data on fish catches as shown in thefollowing table.

(a) Graph both sets of data. Analyze thetrend of the groundfish that have beencaught.

(b) Predict how many groundfish will becaught in 2002 and 2004.

(c) Propose an explanation for the decreasinggroundfish catch in Canadian waters.

(d) Based on the graph of total salmonharvested through aquaculture, will thefish needs of Canadian diets be met?

(e) Add the extra data in the table below toyour graph.

(f) How does this additional informationchange your prediction on how manyfish will be available in 2006?

(g) Why is it important to have long-termdata when working with ecologicaldata? a

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U N I TA Review (continued)

YearTotal GroundfishLanded

Total AquaculturedSalmon Harvested

1990 791 246 49 594

1992 630 574 46 931

1994 452 896 57 147

1996 374 086 72 572

1998 287 498 91 499

2000 229 637 127 336

Fish Catches 1990–2000

YearTotal GroundfishLanded

Total AquaculturedSalmon Harvested

2002 255 994 171 035

2004 306 693 141 580

Fish Catches 2002, 2004Year Wolf Population

1950 100

1955 90

1960 50

1965 20

1970 0

Wolf Population 1950–1970

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Revisit the Big Ideas and FundamentalConcepts 41. The term “ecosystem” is short for

ecological system. Ecosystems are complex,self-regulating systems of organisms andtheir abiotic environments.

(a) What is ecology?

(b) What is a system?

(c) Using the example of an aquaticecosystem that has algae, a fish that eatsalgae, a trout that eats algae eaters, andeagles that eat trout, explain how mattercycles and energy flows through theecosystem.

(d) Suppose the population of algae eaterssuddenly increased due to an increasein algae. How might the ecosystemself-regulate to restore the algae-eaterpopulation?

42. Explain how sustainability and biodiversityare interrelated.

43. What are the five main factors that increaseloss of biodiversity on Earth?

44. What are soils, and what are the mostdevastating effects of human activities onsoils?

45. Suppose you were given the task ofassessing the water quality of a lakeecosystem, and you could havemeasurements of the water done by sendingwater samples to labs for analysis. What aresome types of tests you would order to bedone on the water?

46. Governments are able to take certain kindsof actions that other groups cannot. Forexample, they can make treaties with othercountries and also pass laws. Explain howmaking treaties and passing laws have

worked to promote sustainable ecosystemsin Ontario.

47. What kinds of actions are available toindividuals in Canada to help make us more ecologically sustainable?

Science, Technology, Society,and the Environment

48. The polluting of Lake Erie is a dramaticexample of how activities in yourneighbourhood can affect other parts of theprovince or even the world. Compile a shortreport that outlines how one or morepersonal activities could have a negativeimpact on distant ecosystems. Then,propose solutions to lessen these impacts onecosystems.

49. Governments, groups, and individuals areworking to promote sustainability ofecosystems. Choose one of these that youhave learned about, and explain whatenvironmental issues they have tackled andtheir solutions to the problem. Elaborate onwhat you have learned, and suggestadditional actions that they could take.

Reflection50. Suppose you were to throw a sustainability

party for your friends, family, andneighbours to make them aware of thevarious factors that affect the sustainabilityof ecosystems. What kinds of things do youthink you could do to make them aware ofthe problems and the possible solutions tothese problems?

51. What is the most important thing you havelearned in this unit about the sustainabilityof ecosystems? c

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STSE

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Sustainable A - Mr. Skerrett

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