Biomes and Ecosystems

Biome

• A large, distinct terrestrial region with similar climate, soil, plants, and animals, regardless of location.
• Encompasses many interacting ecosystems.
• Considered the next level of ecological organization above community, ecosystem, and landscape.
• Temperature and precipitation have a significant effect on biome distribution.

Tundra

• A treeless biome in the far north with boggy plains covered by lichens and mosses.
• Harsh, cold winters and extremely short summers.
• Growing season is short, with long days.
• Little precipitation (10-25 cm/year), mostly falling during summer months.
• Soil is nutrient poor and has little detritus.
• Permafrost beneath the surface soil impedes drainage.
• Landscape features broad, shallow lakes and ponds, sluggish streams, and bogs.
• Recovers slowly from even small disturbances.

Tundra Flora and Fauna

• Supports relatively few species but in great numbers.
• Dominant plants: Mosses, lichens, grasses, and grasslike sedges.
• Tundra plants seldom grow taller than 30 cm (12 in).
• Year-round residents: Lemmings, voles, weasels, arctic foxes, snowshoe hares, ptarmigan, snowy owls, and musk oxen.

Boreal Forest (Taiga)

• A region of coniferous forest in the Northern Hemisphere, located just south of the tundra.
• Winters are extremely cold and severe, although not as harsh as those in the tundra.
• Receives little precipitation (50 cm/year).
• Soil is typically acidic and mineral poor, with a thick surface layer of partly decomposed pine and spruce needles.
• Permafrost deep under the surface.
• Features numerous ponds and lakes dug by ice sheets during the last ice age.
• World's top source of industrial wood and wood fiber.

Boreal Forest Flora and Fauna

• Dominant plants: Black and white spruces, balsam fir, eastern larch, and other conifers.
• Conifers have many drought-resistant adaptations, such as needle-like leaves.
• Large species: Caribou, which migrate from the tundra for winter; wolves; brown and black bears; and moose.
• Most boreal mammals are medium-sized to small, including rodents, rabbits, and smaller predators.
• Birds are abundant in the summer but migrate to warmer climates for winter.
• Insects are plentiful, but few amphibians and reptiles occur except in the southern boreal forest.

Temperate Rain Forest

• A coniferous biome with cool weather, dense fog, and high precipitation.
• Occurs on the northwest coast of North America, southeastern Australia, and in southern South America.
• Annual precipitation is high (> 127 cm/year), augmented by condensation of water from dense coastal fogs.
• Seasonal fluctuation is narrow; winters are mild, and summers are cool.
• Relatively nutrient-poor soil, though its organic content may be high.
• Cool temperatures slow the activity of bacterial and fungal decomposers.
• Rich wood producer, supplying lumber and pulpwood.

Temperate Rain Forest Flora

• Dominant plants: Large evergreen trees such as western hemlock, Douglas fir, western red cedar, Sitka spruce, and western arborvitae.
• Rich in epiphytes, mainly mosses, club mosses, lichens, and ferns, which also carpet the ground.