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 Groups of plants and animals tend to be interdependent. 1. Shade 2. Support 3. 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. Climate 2. Sunlight 3. Temperature 4. Precipitation 5. Elevation 6. Soil 7. 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 Forest vegetation grows on every continent except Antarctica. a. Three most common Forest Regions are: 1. Tropical Rain Forests 2. Mid-Latitude Forests 3. 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 Tropical Grasslands Temperate Grasslands

Tropical Grasslands Tropical grasslands AKA savannas grow in warm lands near the Equator. Scattered trees and plants. Animals: Herbivores – Gazelles and Zebras Carnivores – 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.