The Biosphere: Earth’s Diverse Environment Chapter 34

Ecology – the study of the interactions of organisms with their environments. Biosphere – extends from the atmosphere to the depths of the ocean. Biomes – major types of ecological associations that occupy broad geographic regions of land or water.

Limiting factors that influence life in the biosphere Energy source – solar, hydrothermal vents, sulfur bacteria Temperature – range between 0 – 45 0 C allows for metabolism. exceptions (hot springs bacteria, snowy owls, amphibians & reptiles)

Limiting factors that influence life in the biosphere Nutrients – photosynthetic organisms depend on nitrogen and phosphorous gained from the soil. Terrestrial – wind, fire Aquatic factors – oxygen dissolved in water, salinity, current, and tides. (trout require high levels of oxygen, hence the cold, fast moving water)

8 major terrestrial biomes Distinguished by: –vegetation –temperature –rainfall –biological community

Tropical forests Temperature: warm to high Rainfall: varied - heavy Plants: thorny shrubs, deciduous trees, & succulents. (very diverse) Sunlight: little reaches the forest floor. Habitats: floor –> canopy. –Poor soil, due to high temp & heavy rains (leaching). Animals: monkeys, birds, snakes, bats, frogs – tree dwelling.

Savannas Temperature: warm year round Rainfall: moderate rainfall (with long periods of drought) – BIOME DEFINED MAINLY BY THIS Plants: grasses & scattered trees. –growing point below ground & resistance to periods of drought. Habitats: migratory –Poor soil, lack of moisture, grazing animals, & fires inhibit most trees. Animals: large grazing mammals, insects, burrowing animals, predators (lions & cheetahs).

Deserts Temperature: very hot, and cold (Antarctica) Rainfall: dry Plants: none, deep rooted shrubs, succulents. –waxy coating to prevent water loss –many seeds that remain dormant until it rains Sunlight: extreme Habitats: burrows, active at night Animals: ants, birds, rodents, lizards, snakes, & hawks.

Chaparral Temperature: mild winter, hot summer Rainfall: rain in winter, dry in summer Plants: dense shrubs with tough evergreen leaves. Seasonal plants. –Food reserves in roots allow for rapid growth after frequent fires. –Seeds only germinate after hot fire. Animals: deer, birds, rodents, lizards & snakes

Temperate grasslands (prairies) Temperature: relatively cold Rainfall: rain, but periodic severe droughts Plants: grass, mostly treeless –fire & grazing prevents tree growth Habitats: bird nests on ground, burrows. Animals: large grazing mammals (bison, wild horses). –Soil supports diverse microorganisms & small animals. One of the most productive agricultural regions in the world

Temperate (Deciduous) forests Temperature: cold winter, hot summer Rainfall: high precipitation Plants: deciduous trees (oak, hickory, maple) Habitats: rich soil, leaf litter, burrow Animals: invertebrates, mice, shrew, squirrels, birds, bobcats, foxes, bears, & mountain lions. Most destroyed by loggers & urban development.

Taiga (Coniferous forests) Temperature: long cold winters, short wet summers Rainfall: considerable precipitation (snow) Plants: cone bearing evergreens –(spruce, pine, fur) Habitats: soil thin & acidic Animals: moose, elk, bears, wolves, hares, migratory birds. Heavily logged. Largest terrestrial biome!

Tundra Temperature: extremely cold Rainfall: little Plants: no trees, shrubs, grasses, mosses, and lichens. –Permafrost prevents deep root penetration Sunlight: little light for much of the winter, constant daylight in summer Habitats: migratory (summer is a breeding ground), high altitude, permafrost, soil continually saturated due to poor drainage and slow evaporation. Animals: well insulated (oxen & caribou), lemmings, fox, snowy owl. During the summer, clouds of mosquitoes fill the air due to the marshy ground.

Aquatic Biomes Oceans cover about 75% of the Earth’s surface Light and the availability of nutrients are the major factors that shape aquatic communities.

photic zone is the portion of the ocean into which light penetrates. continental shelf where coral reefs are found in warm tropical waters. The pelagic zone is the open ocean aphotic zone is a vast, dark region of the ocean. benthic zone is the ocean bottom

The pelagic zone is the open ocean

Estuaries are productive areas where rivers meet the ocean. –They are often bordered by wetlands The intertidal zone is the wetland at the edge of an estuary or ocean, where water meets land

–Freshwater biomes include lakes, ponds, rivers, streams, and wetlands

Review Questions Describe the chemical and physical factors that affect the biosphere Discuss the role of abiotic and biotic factors in the survival of an organism Describe the characteristics of aquatic biomes Explain the factors contributing to the characteristics of terrestrial biomes Describe the eight major terrestrial biomes