Chapter 2, Section 2

ECOSYSTEMS

II. Ecosystems

Even in harsh polar regions and arid deserts, plants and animals grow in response to their environment.

A. Ecosystems i. Groups of plants and animals tend to be

interdependent. 1. Shade2. Support3. Nourishment

ii. An ecosystem is formed by the interaction of plant life, animal life, and the physical environment in which they live.

iii. Various physical conditions affect the survival and growth of life in an ecosystem.

These factors include:1. Climate2. Sunlight3. Temperature 4. Precipitation5. Elevation6. Soil7. Landforms

iv. Environments with similar conditions tend to support similar communities of plants and animals.

Environmental Change• EX. In a forest, the loss of oak trees will

endanger squirrels and other animals that rely on acorns for food.

• As populations grow, ecosystems change dramatically. – Grasslands become farmland. – Loss of habitat leads to severe decline in animal

and plant populations. – Some species do thrive because of human changes.

Biomes• Geographers classify ecosystems by their

natural plant and animal life. • Biome is used to describe major types of

ecosystems found in various regions of world. – Ex. DECIDUOUS forest Likely to have moderate

climate conditions, oak or maple trees and animals such as deer, squirrels, cardinals and owls.

B. Forest Regions

i. Forest vegetation grows on every continent except Antarctica.

a. Three most common Forest Regions are:1. Tropical Rain Forests2. Mid-Latitude Forests3. Coniferous Forests

However others do exist…

Tropical Rain Forests• Exist in areas near the equator. • Large amounts of rain fall.• Largest are in the Amazon and Congo River

basins. • Tall trees form dense canopy of leaves that

blocks much of the sun from the forest floor. • Varying conditions in layers lead to different

types of plants and animals.• Cover only 6% of the earth but contain more

than half of the earth’s plants and animal species.

Mid-Latitude Forest• Trees are deciduous, they shed their leaves

during one season, usually autumn. • Looks vary by season, stark and bare in the

winter and lush and green in the summer.• Deciduous forests once covered much of

Europe, eastern N. America and Eastern Asia. • Lands in the middle latitudes have a temperate

climate with adequate rainfall, warm summers, and cool or cold winters.

Coniferous Forest• Consists of Pines, spruces, firs. • These trees can survive long, cold winters. • Trees have needles instead of leaves. • Name comes from cones that protect their

seeds. • Bears and deer live here but smaller animals

have adapted to the harsh conditions.

Other Forest Types• Mixed Regions – forest regions overlap. • Coniferous and deciduous grow together in

same areas. Common in Northern U.S.• Chaparral – includes small evergreen trees and

low brushes. • Adapted to Mediterranean climate. = Most

precipitation falls during winter and summers are hot and dry.

C. Grasslands• Central regions of several continents are

covered by grasslands. • Grasslands and forests often mix. • Characteristics of grasslands vary depending

on their latitudes. – 2 types of Grasslands

1. Tropical Grasslands2. Temperate Grasslands

Tropical Grasslands• Tropical grasslands AKA savannas grow in

warm lands near the Equator. • Scattered trees and plants.• Animals:

Herbivores – Gazelles and ZebrasCarnivores – Lions and Hyenas

• Three Seasons:– Wet – Dry– Time of naturally occurring wildfires.

Temperate Grasslands• Prairies– Temperate grasslands of N. America. – More rain = taller grass. – Prairies are now a rare site… Much of grassland region

was plowed under to provide fertile farmland.

Temperate Grassland Continued…• Steppes– Cool, dry, temperate grasslands of Northern

Eurasia and Central Asia similar to Great Plains. – Steppe = comes from Russian word for treeless

plain.

D. Deserts• Desert regions are not just barren expanses of

sand. • Many plants and animals adapt to survive with

almost no water. – Ex. Cactus Plants = store water.– Saguaro cactus expands like a sponge to absorb water.– Cactus leaves are prickly needles for protection.

Deserts continued… • Like plants, animals in the desert are adapted to

extreme temperatures and scarcity of water. – Many do not need to drink at all. – Get moisture from seeds, plants or animals they eat.– Camels can survive for days without food or water by

drawing on the fat stored in their humps.

E. Tundras Alpine Tundra

Exist in high mountains. No trees grow at these high elevations. Small plants and wildflowers grow in sheltered spots. Tiny, brightly colored plants called lichens make

patterns on the rocks.

Tundra continued… • Arctic Tundra – Cold temps. and short growing seasons. – No sunlight for most of winter. – Treeless, covered with grasses, mosses, lichens

and some flowering plants. – Parts of the tundra, a layer of soil just below the

surface (Permafrost) stays permanently frozen.