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Kinds of Ecosystems and Communities

Chapter 2

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Succession

• ____________ - A series of regular, predictable changes in community structure over time.– Activities of organisms change their

surroundings and make the environment suitable for other kinds of organisms.

_____________ - Relatively stable, long-lasting community, primarily determined by climate.

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Succession

• Primary Succession - ___________________________________________________________________________________________________

– Ex. Lava Flow or Glacier Scrape• Secondary Succession - Begins with disturbance of

an existing ecosystem.– Much more commonly observed, and generally

proceeds more rapidly.– Ex.

_________________________________________________________________

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Primary Succession on Land

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____________________________

• Occurs when an existing community is disturbed or destroyed.– With most disturbances, most of the soil

remains, and many nutrients necessary for plant growth may be available for reestablishment of previous ecosystem.

Nearby undamaged communities can serve as sources of seeds and animals.

Tends to be more rapid than primary growth.

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Secondary Succession on Land

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Biomes: Terrestrial Climax Communities

• Biome - Terrestrial climax communities with wide geographic distributions. – Usually defined by undisturbed natural

plant communities.Two main non-biological factors

determining biomes: ___________ ___________

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Biomes of the World

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Elevation Effects on Climate and Vegetation

• As altitude increases, average temperature decreases.– Moving from sea level to mountain tops, it

is possible to pass through a series of biomes similar to what would be encountered moving from the equator to the north pole.

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Desert• Less than 25 cm annual precipitation.

– Unevenly distributed throughout the year.• Climate: Large daily temperature

fluctuations, Likely to be windy, Infrequent cloud cover.

• Many species, but low numbers.• Most species exhibit specialized adaptations

to climate.– Burrow During Day– Water Conservation– Flower only when moisture is available.

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Desert

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Grassland

• Also known as prairies or steppes.• Receives _______ cm of annual

precipitation.• Fire regime usually present.

– Rainfall sporadic enough to cause droughts.

• Historically evolved with large herds of migratory grazing mammals.– Supply fertilizer and discourage invasion

by woody species.

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Grassland

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Savanna

• Receives ________ cm annual precipitation.– Unevenly distributed throughout year.

• Seasonally structured ecosystem.• Fire is a common feature.• Many trees involved in nitrogen fixation.

• Differs from grassland due to scattered trees.

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Savanna

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Mediterranean Shrublands

• Also known as ______________.• Receives 40-100 cm annual precipitation.

– Wet, cool winters and hot, dry summers.Typical of Mediterranean coast, coastal

southern California, as well as parts of Africa, Chile, and Australia.

• Vegetation dominated by woody shrubs adapted to hot, dry summers.

• Fire is a common feature.

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Mediterranean Shrubland

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Tropical Dry Forest

• Annual precipitation ranges 50-200cm.• Many exhibit monsoon climate.

– Rainfall highly seasonal.Drought resistant plants.

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Tropical Dry Forest

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Tropical Rainforest• Located near equator where temperature is relatively

warm and constant.• Most areas receive 200+ cm annual rainfall.

– (Some in excess of 500 cm)• Soil allows high levels of leaching, thus most

nutrients are tied-up in biomass.• Multi-layered canopy.• Very high species diversity:

– Ex. Tree Frogs, Large Vines, Fruit Eating Birds• Threats: Logging, Agriculture, and Ranging

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Tropical Rainforest

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Temperate Deciduous Forest

• Receives _______ cm annual precipitation.– Evenly distributed throughout the year.

• Trees typically lose their leaves during the winter and replace them the following spring.

• Mild winters• Long growing season (6 months).• Relatively few species.• Shade-tolerant spring wildflowers.

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Temperate Deciduous Forest

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Taiga, Northern Coniferous (Boreal) Forest

• Receives _______ cm precipitation annually.• Short, cool summers.• Long winters with abundant snowfall.• Humid climate• Trees adapted to winter conditions:

– Needle-shaped leaves prevent water loss.– Flexible branches

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Taiga, Northern Coniferous (Boreal) Forest

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Tundra

• Less than 25 cm annual precipitation.• Permanently frozen soil (permafrost).• Short, wet summer.• Waterlogged soils and shallow ponds and

pools in spring and summer.• Plants usually less than 20 cm tall.• Alpine Tundra found on mountaintops.• Abundance of Migratory Birds.

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Tundra

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Major Aquatic Ecosystems

• Marine Ecosystems– Freshwater Ecosystems - Low salt content.– Marine Ecosystems - High salt content.

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Marine Ecosystems

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Marine Ecosystems

• Benthic Marine Ecosystems– __________ organisms, attached or non-

attached, live on the ocean bottom.Substrate and Temperature are very

important characteristics in determining benthic community development.

Ex. Seaweed and Angler Fish

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Marine Ecosystems

• Coral Reef Ecosystems - ____________________________________________________________________________________________________________– Contain single-celled algae and carry on

photosynthesis.– Require warm water, thus are found only

near the equator.Most require clear, shallow water with

ample sunlight penetration.

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Marine Ecosystems

• __________________________– Occupy region near shore.– Trees tolerate high salt content.

Excrete salt from leaves.– Extensively developed roots.

Can extend above water.– Trap sediment in shallow areas.

Develop terrestrial ecosystems.

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Marine Ecosystems

• Estuaries– Shallow, partially enclosed areas where

freshwater enters the ocean.– Extensive production because areas are

shallow, warm, and nutrient-rich.Nursery sites for fish and crustaceans.

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Estuary

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Freshwater Ecosystems

• Two broad categories:– __________________

Lakes, Ponds, and Reservoirs– _______________ (Downhill)

Streams and Rivers

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Review

• Succession– Primary– Secondary– Climax Community– Terrestrial– Aquatic

• Biomes• Aquatic Ecosystems

– Freshwater– Marine

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