Communities and Biomes

Community• Community: A collection of several interacting

populations that inhabit a common environment.

Limiting Factors

– Factors that affect an organism’s ability to survive in its environment, such as the availability of water and food, predators, and temperature, are called limiting factors.

• A limiting factor is any biotic or abiotic factor that restricts the existence, numbers, reproduction, or disturbance of organisms.

Ranges of Tolerance

• The ability of an organism to withstand fluctuations in biotic and abiotic environmental factors is known as tolerance

Ecological Succession• Ecosystems are constantly changing in response to

natural and human disturbances.• As an ecosystem changes, older inhabitants

gradually die out and new organisms move in, causing further changes in the community.

Ecological Succession• Ecological succession is the series of predictable

changes that occur in a community over time.– Primary succession takes place on bare rock

surfaces where no soil exists. Pioneer species are the first species to live in these areas.

– Secondary succession occurs when a disturbance changes a community without removing soil.

Primary Succession

Secondary Succession

Biotic and Abiotic Factors

• Organisms in ecosystems are affected by both biotic and abiotic factors.

• Biotic factors are all of the living things with which organisms interact.

• Abiotic factors are nonliving, physical things. (Ex. temperature and soil type)

• Together, biotic and abiotic factors determine the survival and growth of an organism and the productivity of the ecosystem in which and organism lives.

Biotic Factors

ECOSYSTEM

Abiotic Factors

Abiotic and Biotic Factors

Ecological Succession Video

• http://www.youtube.com/watch?v=V49IovRSJDs

Climate• In the atmosphere, temperature, precipitation,

and other environmental factors combine to produce weather and climate.

• Weather: is the day-to-day condition of Earth’s atmosphere at a certain time and place.

• Climate: is the average yearly condition of temperature and precipitation in a region.• Climate affects ecosystems.

The Greenhouse Effect• Carbon dioxide and other atmospheric gases trap

heat energy and maintain Earth’s temperature range.• These gases function like the glass windows of a

greenhouse.• The trapping of heat by gases in the atmosphere is

called the greenhouse effect.• This greenhouse effect helps temperatures on Earth stay

within a range that supports life.

The Greenhouse Effect

The Effect of Latitude on Climate

• Latitude also affects climate. Earth has 3 main climate zones: polar, temperate, and tropical.– Polar Zones are cold areas where the sun’s rays

strike Earth at a very long angle.– Temperate Zones sit between the polar zones and

the tropics. The climate in these zones ranges from hot to cold, depending on the season.

– The Tropical Zones or tropics, is near the equator. The climate here is almost always warm.

Sunlight

Most direct sunlight

Sunlight

Sunlight

Sunlight

90°N North Pole

66.5°N

23.5°N

0°

23.5°S

66.5°S90°S South Pole

Arctic circle

Tropic of Cancer

Equator

Tropic of Capricorn

Arctic circle

The Effect of Latitude on Climate

Heat Transport in the Biosphere• Unequal heating of Earth’s surface also causes

winds and ocean currents. • Wind and ocean currents move heat through

the biosphere.

Biomes

• A biome is a group of land communities that covers a large area and has a certain soil type and climate

• Within a biome, there maybe microclimates• A microclimate is a small area where the climate

differs from that of the surrounding area.

The Major Biomes• There are ten major biomes:

– Tropical Rain Forest, Tropical Dry Forest, Tropical Savanna

– Desert– Temperate Grassland, Temperate Woodland and

Shrubland, Temperate Forest– Northwestern Coniferous Forest, Boreal Forest (or

Taiga)– Tundra

• Each biome has its own set of abiotic factors and a typical collection of organisms.

• Some areas, such as mountains and polar ice caps, do not fall neatly into the major biomes

Compare/Contrast Table of Biomes

Ten Major BiomesBiome Precipitation Temperature Soil Diversity Trees GrassesTropical Rain Forest high hot poor high dense sparse

Tropical Dry Forest variable mild rich moderate medium medium

Tropical Savanna variable mild clay moderate sparse denseDesert low variable poor moderate sparse sparseTemperate Grassland moderate summer hot rich moderate absent dense

Temperate woodland and Shrubland

summer low, winter moderate

summer hot poor low medium medium

Temperate Forest moderate summer moderate, winter cold

rich high dense sparse

Northwestern Coniferous Forest

high summer mild, winter cold

rocky, acidic low dense sparse

Boreal Forest moderate summer mild, winter cool

poor, acidic moderate dense sparse

Tundra low summer mild, winter cold

poor low absent medium

Tropical rain forest

Tropical dry forest

Tropical savanna Temperate woodlandand shrubland

Desert

Temperate grassland

Boreal forest(Taiga)

Northwesternconiferous forest

Temperate forest

Mountains andice caps

Tundra

The World’s Major Land Biomes

Aquatic Biomes

• Unlike land biomes, which are grouped geographically, aquatic biomes are grouped by the abiotic factors that affect them.

• Aquatic biomes are described mainly by the depth, flow, temperature, and chemistry of their water.

Aquatic Energy• In many aquatic biomes, tiny free-floating swimming

organisms can be found. These organisms are called plankton.

• There are 2 types of plankton (phytoplankton and zooplankton)– Phytoplankton are single-celled algae that use nutrients in

water to make food. They form the base of many aquatic food webs.

– Zooplankton are animals that feed on phytoplankton

Aquatic Biomes• There are 3 main groups of aquatic biomes:• 1. Freshwater biomes can be divided into several

types.

– Flowing-water biomes (rivers and streams) flow over land.

– Standing-water biomes include lakes and ponds– Freshwater wetlands include bogs, marshes, and

swamps. In wetlands, water covers the soil or is present at or near the surface for at least part of year.

Bogs, Marshes, and Swamps

Aquatic Biomes

2. Estuaries are wetlands formed where rivers meet the sea. They contain a mixture of fresh and salt water. Most food made in estuaries enters food webs as tiny pieces of organic matter, called detritus.– Salt marshes are temperate estuaries. Salt-tolerant

grasses and sea grasses are the dominant plant life in salt marshes.

– Mangrove swamps are tropical estuaries. The dominant plant life in mangrove swamps includes several species of salt-tolerant trees, called mangroves, and sea grasses.

Aquatic Biomes

3. Marine biomes exist in the ocean. The ocean is divided into zones based on how much light penetrates the water.– The photic zone is the well-lit upper layer of water.

Photosynthesis can take place here.– The aphotic zone is the permanently dark lower layer

of water. Producers here use chemosynthesis to make food.

Oceans• The ocean is also divided into zones based on depth and

distance from shore: the intertidal zone, the coastal ocean, and the open ocean, and benthic zone.

Marine BiomesOrganisms in the intertidal zone are exposed to regular and extreme changes in their surroundings. (tides)

The coastal zone is relatively shallow, lies entirely within the photic zone, and is often rich in plankton and other organisms. Coral reefs grow in tropical coastal oceans.

Marine BiomesThe open ocean is the largest zone, covering more than 90 percent of the surface area of the world’s oceans. These areas typically have low levels of nutrients and support only small producers.

Benthic zone is the bottom of the ocean, contains organisms that live attached to or near the bottom.

landCoastalocean

Openocean

Oceantrench

Aphotic zone

Photic zone

Continentalshelf

Continental slope andcontinental rise

Abyssalplain

200m1000m

4000m

6000m

10,000m

Zones of a Marine Biomes