Chapter 3:Communities, Biomes, and Ecosystems

How would you describe your Community?

Did you include your

family and friends?

Did you include your

school?

Did you include plants and

animals ?

A biological community is a group of interacting populations that occupy the same area at the same time.

What are abiotic

factors and how

might they affect a

community?

Any abiotic or biotic

factor that restricts the

numbers, reproduction, or

distribution of organisms

is called a limiting factor.

What do you think

are some abiotic and

biotic limiting

factors in a

community?

Abiotic limiting factors include

sunlight, climate, temperature,

water, nutrients, fire, soil

chemistry, and space.

Biotic limiting factors include

living things, such as other plants

and animal species.

Range of

Tolerance

For any Environmental factor, there is

an upper limit and a lower limit that

define the conditions in which an

organism can survive.

The ability of any organism

to survive when subjected to

abiotic or biotic factors is

called tolerance.

Within any particular ecosystem

abiotic and biotic factors are

constantly changing.

May be in small ways such as a

tree falling or on a larger scale

such as a population going

extinct.

The change in an ecosystem

that happens when one

community replaces another as

a result of changing abiotic and

biotic factors is called

ecological succession.

1. Primary successionEstablishment of a community in an area of

bare rock or sand, where no topsoil is present.

A mature community can eventually develop from

bare rock. That community will then be known as a

climax community because there is little to no

change in the composition of species.

2. Secondary succession

Secondary succession is the orderly

and predictable change that takes

place after a community or

organisms has been removed but the

soil has remained intact.

Section 2:

Terrestrial Biomes

Effects of Latitude and Climate

Weather is the condition of the atmosphere at a specific place and time.

In order to understand why weather varies, it is important to first understand latitude and climate conditions.

Latitude

The distance of any point on the surface

of earth north or south from the

equator is latitude.

Latitude ranges from 0° at the equator to 90°at the poles.

• Light from the sun strikes the earth more directly at the equator than at the poles. As a result the earth is heated differently at areas.

• Ecologist refer to these areas as polar, Temperate and tropical zones.

Climate

The average weather conditions in an area, including temperature and precipitation, describe the

area’s climate.

An areas latitude has a large effect on its climate.

Other abiotic factors such as elevation, continental landmass, and ocean currents also affect climate.

Major land biomes

Biomes are classified primarily according to the characteristics

of their plants and animals, along with their temperature

and precipitation.

Tundra Extends in a band

below the polar ice

caps across northern

Europe, north

America, and Siberia

in Asia.

Treeless biome with a

layer of permanently

frozen soil below the

surface called

permafrost.

Boreal ForestSouth of the tundra.

Band of dense evergreen forest that extends across N. America, Europe, and Asia.

Also called Northern Coniferous Forest, or taiga.

Longer summers than tundra

Lacks permafrost.

Temperate Forest Cover much of south Eastern

Canada, the eastern united states, most of Europe, and parts of Asia and Australia.

Composed mostly of broad-leaved, deciduous trees.

Shed leaves in autumn.

Fallen leaves return nutrients to the soil.

All four seasons occur in the temperate forest.

Temperate Woodland and Shrubland

Found in areas of less annual rainfall than temperate forest.

Areas surrounding Mediterranean seas, on the west coast of North and South America, in south Africa, and Australia.

Dominated by shrubs.

Temperate GrasslandCharacterized by fertile soils that

support a thick layer of grass.

Grazing animals keep the grass low.

Found in the middle latitudes of North America, South America, Asia , Africa , and Australia.

Called “Steppes” in Asia; “prairies” in N. America ;” pampas and Llanos” in S. America ; ”Savannas” in Africa; and “Rangelands” in Australia.

DesertExist on every

continent except for Europe.

An Area in which annual rate of evaporation exceeds the rate of precipitation.

Home to a wide variety of animals.

Tropical SavannaCharacterized by grasses

and scattered trees in climate that receives less precipitation than some other tropical areas.

Occur in Africa, S.America , and Australia.

Lions, Zebras, elephants cheetahs, etc. are common to this area.

Tropical seasonal forest

Also called tropical dry forests

Grow in areas of Africa, Asia, Australia, and South and Central America.

Tropical rain forest Warmer temperatures and large

amounts of rainfall throughout the year.

Found in much of Central and South America, Southern Asia, West central Africa, and northeastern Australia.

Most diverse of all land biomes.

Tall, broad-leaved trees with branches heavy with moss, ferns, and orchids make up the canopy of the tropical rain forest.

Shorter trees, shrubs, and plants make up another layer (understory).

Other Terrestrial Areas

Mountains As you go up a mountain,

Abiotic factors such as temperature and precipitation, change.

Because of this many communities can exist on the side of a mountain.

Other Terrestrial AreasPolar regions

Border the tundra at high altitudes.

Cold all year.

Coldest temperature ever recorded, -89°C = -128°F

Is able to sustain life, even with extreme temperatures.

Section 3:

Aquatic Ecosystems

Fresh Water Ecosystems: On earth the major fresh water ecosystems include ponds, lakes, streams, rivers, and wetlands.

• Plants and animals in these ecosystems are adapted to the low salt concentration (compared to the ocean) and are unable to survive in areas of high concentration.

~2.5 % of the water on earth is freshwater

Of that 2.5%,

68.9 % is contained in glaciers

30.8 % is groundwater

0.3 % are found in ponds, lakes, rivers,

streams, and wetlands.

Rivers and streams

The water in rivers and streams flows in

one direction, beginning at a source known as a headwaterand traveling to the mouth, where the

flowing water empties into a larger body of

water.

The slope of the landscape will determine the speed of the water flow.

Land is steep = flows quickly

This quick flow will cause lots of sediment to be picked up and carried by the water.

Sediment is a material that is deposited by water, wind, or glaciers.

Lakes and

Ponds

An inland body of standing water is called a lake

or a pond.

Ranging in many different sizes.

Temperature regions in a lake depends on

the season.

In the winter, most of the water in a

lake or pond is the same temperature.

In the summer, the warmer water on top is less

dense than the colder water at the bottom.

• During the spring and fall, as the water warms or cools, turnovers occur.

• The top and bottom layers of the water mix and this results in a uniform water temperature.

• This mix circulates oxygen and brings nutrients from the bottom to the surface.

Nutrient poor lakes, called oligotrophic lakes, are

found often high in the mountains.

Few plants and animals are found as a result of small

amounts of organic mater and nutrients.

Nutrient-rich lakes, called eutrophic lakes, usually

are found at lower altitudes.

Many plants and animal species are present as a result of

organic matter and plentiful amounts of nutrients.

Lakes and ponds are divided into three zones

based on the amount of sunlight that penetrates

the water.

The area closest to the shore is called the littoral

zone.

The water in this zone is shallow ( allows sunlight to hit the

bottom).

In these shallow waters organisms such as plants and algae

thrive.

Area of high photosynthesis

Consumers habitat this zone such as frogs, turtles, worms,

coruscations, insect larva and fish.

The limnetic zone is the open water area that is well

lit and is dominated by plankton.

Many species of fish live in this zone because food is

readily available.

• Plankton are free

floating photosynthetic

autotrophs that live in

fresh water or marine

ecosystems.

The Profundal zone is the darkest part of a lake.

Much colder and lower in oxygen than the other

two zones.

Limited number of species live in this harsh

environment.

Transitional

Aquatic

Ecosystems

Wetlands Area saturated

with water that supports aquatic plants.

Areas of land such as:

Marshes

Swamps

Bogs

Plant Species: Duckweed

Pond lilies

Cattails

Sedges

Mangroves

Cypress

Willows

Animal species: High level of species diversity

From amphibians, reptiles, birds, and mammals.

EstuariesEcosystem formed when freshwater from a river

or a stream merges with the salt water from the ocean.

o Dominant producers in these areas are algae, seaweeds, and marine grasses.

o Many species of marine fishes use estuaries as nurseries for their young.

Salt Marshes

Similar to Estuaries

Composed of salt-tolerant grasses

Support different species of animals, such as shrimp and shellfish.

Marine

Ecosystems

Intertidal ZoneNarrow band where the ocean meets land.

Divided into vertical zones.

Spray zone

Dry most of the time.

Only during high tide is this area sprayed with water

Few plants and animals live in this environment.

High-tide Zone Under water

only under high tide (receives more water than the spray zone)

Plants and animals are able to live in this zone

Mid-tide zone

Undergoes several disruption twice a day as the tides cover and uncover the shoreline with water.

Organisms in this environment must adapt to long periods of air and water.

Low-tide zone

Covered with water unless the tide is unusually low.

Most populated area.

Open Ocean

The open ocean is divided into zones

Pelagic zone

Abyssal zone

Benthic zone

Area to depth about 200m of the pelagic zone is called the Photic zone (euphotic zone).

Shallow enough for sunlight to be able to penetrate.

Divided into the epipelagic zone and mesopelagic zone

Autotrophic organisms:

Seaweed

Plankton

Animals:

Fish

Sea turtles

Jellyfish

Whales

Dolphins

Below the photic zone is the Aphotic zone.

Area where sunlight is unable to penetrate.

Remains in constant darkness

cold

Organisms that depend on light energy cannot live in this zone.

Benthic zone; Area along ocean floor that consist of sand, salt, and dead organisms

As depth increases, light and temperature decreases.

Species diversity increases with depth (not hypothermal zone)

Deepest region of the ocean is called the abyssal zone.

Very cold waters

Most organisms in this region rely on food material that drifts down from the zones above.

Coral reefs

Most diverse ecosystems

Found in warm shallow marine waters

Form natural barriers between continents that support the shoreline from erosion

Dominant organisms are corals