The Biosphere

What is Ecology?Ecology – the scientific study of interactions among

organisms and between organisms and their environment, or surroundings.

Biosphere – the combined portions of the planet in which all of the life exists, including land, water, and air, or atmosphere. It extends from about 8 km above Earth’s surface to 11 km below the ocean surface.

Levels of OrganizationTo understand relationships within the biosphere,

ecologists ask questions about events and organisms that range in complexity from a single individual t o the

entire biosphere.

Levels of OrganizationSpecies - a group of organisms so similar to one another

that they can interbreed and produce fertile offspring.

Populations – groups of individuals that belong to the same species and live in the same area.

Communities – different populations that live together in a defined area.

–These clams that live near

an ocean vent constitute a population

Levels of Organization

Ecosystem – a collection of all organisms that live in a particular place, together with their nonliving, or physical, environment.

Biome – a group of ecosystems that have the same climate and similar dominant communities.

Ecological MethodsRegardless of the tools they use, scientists conduc t

modern ecological research using three basic approaches: observing, experimenting, and modeling.

All of these approaches rely on the application of scientific methods to guide ecological inquiry.

Energy FlowSunlight is the main energy

source for life on Earth.

Some types of organisms rely on the energy stored in

inorganic chemical compounds.

Autotrophs – plants, some algae and certain bacteria can capture energy from sunlight or chemicals and use that energy to produce food.

Producers – organisms that make their own food (autotrophs).

Energy Flow –With NO Light!

Chemosynthesis – when organisms use chemical energy to produce carbohydrates. Such as sulfur bacteria converting sulfur compounds into carbohydrates around thermal vents in the ocean. Ex: Chemosynthetic Bacteria

Thermal vent

Energy Flow – From the Sun

Photosynthesis – the conversion of light energy into chemical energy which is stored within organic compounds.

Energy Flow – ConsumersHeterotrophs – organisms that rely on other organisms

for their energy and food supply; also known as consumers .

Consumers include animals, bacteria & fungi

Energy Flow – Consumer TypesHerbivores – animals that obtain energy by eating only

plants. Ex: cows & caterpillars

Carnivores – organisms that obtain energy by eating animals. Ex: snakes, dogs & owls

Omnivores – organisms that obtain energy by eating both plants and animals. Ex: humans, bears & crows

Detritivores – organisms that feed on plants and animal remains and dead matter (detritus).

Ex: mites, earthworms & snails

Decomposers – break down organic matter. Ex: bacteria & fungi

Feeding RelationshipsEnergy flows through an ecosystem in

one direction, from the sun or inorganic compounds to autotrophs

(producers) and then to various heterotrophs (consumers).

Food chain – a series of steps in which organisms transfer energy by eating and being eaten.

TROPHIC LEVEL

Quaternaryconsumers

Tertiaryconsumers

Carnivore Carnivore

Carnivore Carnivore

Carnivore Carnivore

Herbivore Zooplankton

Plant Phytoplankton

Secondaryconsumers

Primaryconsumers

Producers

A TERRESTRIAL FOOD CHAIN AN AQUATIC FOOD CHAIN

Trophic Levels•Each step in a food chain or food web is called a trophic level.

•Producers make up the first trophic level.

•Consumers make up the second, third, or higher trophic levels.

•Consumers depend on the trophic level below it for energy.

Tertiaryandsecondaryconsumers

Secondaryandprimaryconsumers

Primaryconsumers

Producers

(Plants, algae,phytoplankton)

Detritivores

(Prokaryotes, fungi,certain animals)

Wastes anddead organisms

Food Web – the feeding relationships among the various organisms in an ecosystem form a network of complex interactions; the interactions of all the food chains in an ecosystem.

Ecological PyramidsAn ecological pyramid is a diagram that shows the

relative amounts of energy or matter contained with in each trophic level in a food chain or food web.

Energy Pyramid – shows the relative amount of energy available at each trophic level.

Only about 10 % of the energy available within one trophic level is transferred to organisms at the nex t trophic level.

Ecological PyramidsBiomass – the total amount of living tissue within a

given trophic level. Biomass is usually expressed in terms of grams of organic matter per unit area.

Cycles of MatterUnlike the one-way flow of energy, matter is recycl ed

within and between ecosystems.

Biogeochemical cycle – process in which elements, chemical compounds, and other forms of matter are passed from one organism to another and from one pa rt of the biosphere to another.

Solarheat

Precipitationover the sea(283)

Net movementof water vaporby wind (36)

Flow of waterfrom land to sea(36)

Water vaporover the sea

Oceans

Evaporationfrom the sea(319)

Evaporationandtranspiration(59)

Water vaporover the land

Precipitationover the land(95)

Surface waterand groundwater

Water Cycle

Water CycleEvaporation – the process by which water changes from

liquid form to an atmosphere gas.

Transpiration – when water enters the atmosphere by evaporating from leaves of plants.

Nutrient CyclesNutrients – all the chemical substances that an organism

needs to sustain life.

Every living organism needs nutrients to build tiss ues and carry out essential life functions. Like water , nutrients are passed between organisms and the

environment through biochemical cycles.

Carbon CycleCO2 in atmosphere

Cellular respiration

Higher-levelconsumers

Primaryconsumers

Plants,algae,

cyanobacteria

Photosynthesis

Wood andfossil fuels

Detritivores(soil microbes

and others) Detritus

Decomposition

Burning

Nitrogen Cycle

• Nitrogen is plentiful in the atmosphere as N 2

– But plants cannot use N 2

Nitrogen Fixation• Various bacteria in soil (and legume root nodules)

convert N 2 to nitrogen compounds that plants can use– Ammonium (NH 4

+) and nitrate (NO 3–)

• Some bacteria break down organic matter and recycle nitrogen as ammonium or nitrate to plants

Denitrification• Other bacteria return N 2 to the atmosphere by

converting nitrates into N 2

Nitrogen (N 2) in atmosphere

Amino acidsand proteins in

plants and animalsAssimilationby plants

Denitrifyingbacteria

Nitrates(NO3

–)

Nitrifyingbacteria

Detritus

Detritivores

Decomposition

Ammonium (NH 4+)

Nitrogenfixation

Nitrogen-fixingbacteria in soil

Nitrogen-fixingbacteria in root

nodules of legumes

Nitrogenfixation

Nitrogen Cycle

Phosphorus Cycle

Phosphates (compounds containing PO 43-) and other

minerals are added to the soil by the gradual weath ering of rock.

Consumers obtain phosphorus in organic form from plants.

Phosphates are returned to the soil through excreti on by animals and the actions of decomposers.

Phosphorus is essential to living organisms because it forms part of important life-sustaining molecules s uch as DNA & RNA.

Upliftingof rock

Phosphatesin solution

Weatheringof rock

Phosphatesin rock

Phosphatesin organic

compounds

Detritus

Detritivoresin soil

Phosphatesin soil

(inorganic)

Rock Precipitated(solid) phosphates

Plants

Animals

Decomposition

Runoff

Phosphorus Cycle

Nutrient LimitationPrimary productivity – the rate at which matter is created

by producers.

Limiting nutrients – single nutrient that either is scarce or cycles very slowly, limiting the growth of organisms in an ecosystem.

Algal bloom – the result of runoff from heavily fertilized fields – the result is often immediate increase in the amount of algae and other producers.

Ecosystems & Communities

What is Climate?Weather – the day-to-day condition of Earth’s

atmosphere at a particular time and place.

Climate – refers to the average, year-after-year conditions of temperature and precipitation in a particular region.

The Greenhouse EffectCarbon dioxide, methane, water vapor, and a few oth er

atmospheric gases trap heat energy and maintain Ear th’s temperature range.

Greenhouse effect – natural situation in which heat is retained in Earth’s atmosphere by carbon dioxide, methane, water vapor, and other gases.

Light

Heat

GREENHOUSE EFFECT:CO2 lets sunlight through butretains the heat generatedby the sun

CO2

Adding CO2 to the airincreases the greenhouse effect

Removal of CO2 from the air byphotosynthesizing plants and

algae decreases the greenhouse

effect

CO2 CO2

The Greenhouse Effect

The Effect of Latitude on ClimateAs a result of differences in latitude and thus the angle of

heating. Earth has three main climate zones: polar , temperate, and tropical.

The Effect of Latitude on ClimatePolar zones – cold areas where the sun’s rays strike

Earth at very low angles.

Temperate zones – sit between the polar zones and the tropics. Because temperate zones are more affected by the changing angle of the sun over the course of a year, the climate in these zones ranges from hot to cold, depending on the season.

Tropical zone – or tropics, is near the equator, between 23.5° North and 23.5 ° South latitudes. Direct sunlight year-round, makes the climate almost always warm.

Heat Transport in the Biosphere

What Shapes an Ecosystem?Biotic Factors – biological influences on organisms

within an ecosystem. (living factors)

Abiotic Factors – physical, or nonliving factors that shape an ecosystem.

Together, biotic and abiotic factors determine the survival and growth of an organism and the producti vity

of the ecosystem in which the organism lives.

What Shapes an Ecosystem?Habitat – the area where an organism lives. Includes

both biotic and abiotic factors.

Niche – is the full range of physical and biological conditions in which the organism lives and the way in which the organism uses those conditions.

Realized Niche – the range of resources an organism actually uses.

Fundamental niche - the range of conditions that a species can potentially tolerate and the range of resources it can potentially use.

Community InteractionsCommunity interactions, such as competition, predat ion, and various forms of symbiosis, can powerfully affe ct an

ecosystem.

Resource – refers to any necessity of life, such as water, nutrients, light, food, or space.

Community InteractionsCompetitive Exclusion Principle – states that no two species can occupy the same niche in the same habit at

La Palma, Dominican Republic –competition for food is minimized because each lizard species perches in a certain microhabitat (niche).

Community InteractionsPredation – the interaction in which one organism

captures and feeds on another organism.

Studies show that predation can actually help maint ain diversity. Gray wolves were killed out in many par ts of North America. What happened to deer and herbivore populations? What happened to many plant species i n North American ecosystems?

Community InteractionsMimicry – a harmless species resembles a poisonous or

distasteful species.

Batesian mimicry – a palatable or harmless species mimics the an unpalatable or harmful model.

Müllerian mimicry – two or more unpalatable species resemble each other.

Community InteractionsCamouflage or cryptic coloration – a passive defense that makes potential prey difficult to spot against its background.

Aposematic coloration – warning coloration; seen in animals with effective chemical defenses.

SymbiosisAny relationship in which two species live closely

together.

Mutualism – both species benefit from the relationship.

SymbiosisCommensalism – one member of the association

benefits and the other is neither helped nor harmed.

SymbiosisParasitism – one organism lives on or inside another

organism and harms it.

Ecological SuccessionEcosystems are constantly changing in response to natural and human disturbances. As an ecosystem

changes, older inhabitants gradually die out and ne w organisms move in, causing further changes in the

community.

Ecological succession – a series of predictable changes that occurs in a community over time.

Ecological SuccessionPrimary Succession – on land, succession that occurs on

surfaces where no soil exists.

Pioneer Species – the first species to populate an area.

Ecological SuccessionSecondary Succession – when a disturbance of some kind changes an existing community without removing the soil.

Tropical Rainforest•The tropical rain forest is the most diverse ecosys tem

on Earth.

•Large-scale human destruction of tropical rain forests continues to endanger many species

–It may also alter world climate

Tropical Savanna•Grasslands with scattered trees.

•Drier, tropical areas and some nontropical areas ar e characterized by the savanna

• Deserts are the driest of all terrestrial biomes– They are characterized by low and unpredictable

rainfall

– Desertification is a significant environmental problem

• The chaparral biome is a shrubland with cool, rainy winters and dry, hot summers

• Chaparral vegetation is adapted to periodic fires

Temperate Woodland & Shrubland

• Temperate grasslands are found in the interiors of the continents, where winters are cold

– Drought, fires, and grazing animals prevent trees from growing

– Farms have replaced most of North America's temperate grasslands

Temperate Grassland

• Temperate deciduous forests grow where there is sufficient moisture to support the growth of large trees

– Nearly all of the original deciduous forests in North America have been drastically altered by agriculture and urban development

Temperate Forest

• The northern coniferous forest, or taiga, is the largest terrestrial biome on Earth

Coniferous Forest or Taiga

• The taiga is characterized by long, cold winters and short, wet summers

• Coastal coniferous forests of the Pacific Northwest are actually temperate rain forests

• The arctic tundra lies between the taiga and the permanently frozen polar regions– It is a treeless

biome characterized by extreme cold, wind, and permafrost

– Permafrost is continuously frozen subsoil

Tundra

Aquatic BiomesAquatic ecosystems are determined primarily by the

depth, flow, temperature, and chemistry of the over lying water.

Freshwater Ecosystems :

1. Flowing-water ecosystems – rivers, streams, creeks & brooks

2. Standing-water ecosystems – lakes & ponds

Plankton – general term for the tiny, free-floating or weakly swimming organisms that live in both freshwa ter and saltwater.

Phytoplankton – single-celled algae

Zooplankton – planktonic animals that feed upon phytoplankton.

EstuariesEstuaries – are wetlands formed where rivers meet the

sea. Salinity ranges from 1% - 3%.

Salt marshes – temperate-zone estuaries dominated by salt-tolerant grasses above the low tide line and b y sea-grasses under the water.

Mangrove swamps – coastal wetlands that are dominated by salt-tolerant trees.

WetlandWetland – an ecosystem in which water either covers the soil or is present at or near the surface of the so il for at least part of the year.

•Includes: bogs, marshes & swamps

•Very rich in species diversity

Marine EcosystemsPhotic zone – the upper layer of the ocean where sunlight

penetrates; the first 200 m.

Aphotic zone – the region of ocean that is permanently dark.

Marine Ecosystems

Intertidal Zone

•Wetland at the edge of an estuary or ocean, where water

meets the land.

•Often flooded by high tides and then left dry during low

tides.

Marine EcosystemsCoral Reefs

•Found in warm tropical waters above the continental shelf.

•Easily degraded by: pollution, native & introduced predators, & souvenir hunters

Marine EcosystemsBenthic Zone

•Ocean bottom

•Many organisms rely on thermal-vent microhabitats f or food.

•Other animals depend upon food that has drifted dow n from the photic zone.