Ecosystems 2-2

I. Ecosystems A. Ecosystem – formed by the interaction of plant life, animal life, and the physical environment in which they live B. Environmental change 1. the loss of natural habitat usually leads to severe declines in animal and plant populations C. Biomes – major types of ecosystems that can be found in various regions throughout the world 1. classified by their natural plant and animal life

II. Forest Regions A. Tropical Rain Forest 1. areas near the Equator 2. temperature is warm and great amounts of rain fall 3. largest are in the Amazon River basin in South America & the Congo River basin in Africa 4. tall trees form like canopies & block much of the sun from the forest floor 5. rain forests cover only about 6% of the earth’s surface, but contain more than half of the earth’s plant and animal species

B. Mid-Latitude Forest 1. deciduous – trees that shed their leaves during one season, usually autumn 2. much of this type of forest has been cleared to make room for housing developments and large cities 3. very little of the natural vegetation remains 4. temperate climate with adequate rainfall, warm summers, and cool or cold winters

C. Coniferous Forest 1. coniferous – trees that have cones that protect their seeds 2. located in colder areas 3. includes pines, spruces, firs, and their relatives that have long, thin needles rather than leaves 4. some large animals (moose and bears) live in these forests but most animals are much smaller

D. Other Forest Types 1. mixed regions – include coniferous and deciduous trees (northern U.S.) 2. chaparral – small evergreen trees and low bushes or scrub (Mediterranean & Australia)

III. Grasslands A. Tropical Grasslands 1. savannas – huge tropical grasslands which grow in warm lands near the Equator 2. wet season – trees and plants grow tall and green 3. dry season – trees and grasses turn brown and die above ground (remain alive underground) 4. wildfire season – help maintain the savanna by encouraging new grasses to grow 5. 2 types of animals are found in savannas: a. Herbivores – plant-eating animals (gazelles & zebras) b. Carnivores – meat-eating animals (lions & hyenas)

B. Temperate Grasslands 1. prairies – temperate grassland characterized by a variety of grasses 2. found in cooler parts of the world, like N. America 3. in the U.S., prairies in the east had tall grasses with colorful wildflowers…as you move west, grasses are shorter and dryer 4. little of the natural prairie vegetation is left because they plowed these areas to become farmland

IV. Deserts A. Many plants and animals have adapted to survive with almost no water B. Cactus plants store water in their thick stems for later retrieval (hundreds of gallons) C. Many others have seeds that can survive for years without water to sprout D. Most desert animals go without water…instead they get moisture from the seeds, plants, or other animals they eat

V. Tundras A. Tundra – region where temperatures are always cool or cold & only specialized plants can grow 1. alpine tundra exists in high mountains – only small plants and wildflowers…no trees 2. arctic tundra – treeless, covered with grasses, mosses, lichens, and flowering plants…goes without sunlight for most of the winter 3. permafrost – layer of soil just below the surface that stays permanently frozen 4. some plants and animals