A biome is a large geographical area that provides a home to distinctive plant and animal life. Biomes are defined by their climate, geography, major plant life and adaptations of their life-forms. Biomes are not permanent features of the Earth's surface. Climate change, human activity and geological transformations can alter them.
Temperate forests occur in areas of Asia, Europe and North America with moderate climates. They get about 30 to 60 inches of evenly distributed precipitation a year and have rich soil and diverse vegetation. Temperate forests contain three to four tree species in every 0.33 square mile. Familiar species include broadleaf trees, such as oaks, maples and beeches. Animals include skunks, birds, deer, wolves, squirrels, mountain lions and bears.
Alpine tundras are mostly treeless areas found above the treeline in mountainous regions around the world. They have short growing seasons, and their rocky subsoils limit plant growth. The rugged landscape harbors small plants, such as grasses, dwarf-trees, shrubs and heather. Animals include pikas, mountain goats and marmots.
Also called taigas, boreal forests are cold, conifer-dominated forests covering large portions of Europe, Asia and North America. They have short damp summers; long, cold winters; and short growing seasons. Their thin soil is acidic and nutrient poor. Precipitation mostly comes in the form of snow and is roughly equivalent to 16 to 40 inches of rain a year. Animals inhabiting the boreal forest include weasels, woodpeckers, hawks, moose, bear, squirrels, fox and bats.
Cold deserts exist in Greenland, Antarctica and the Nearctic. They have temperatures of 28 to 39 degrees F in the winter and 70 to 78 degrees F in the summer. The annual precipitation in cold deserts ranges between 6 and 8 inches a year but can fall as low as 3.5 inches or climb as high as 18 inches. Heavy cold desert soil contains large amounts of silt and salt. Plants include sagebrush, shadscale and various deciduous plants with spiny leaves. Animals include various rats and mice, jack rabbits, squirrels and lizards.
Temperate rainforests exist in temperate areas along the northwestern coast of North America and parts of Australia, New Zealand and Chile. They have 78 to 118 inches of rain and snow and relatively warm temperatures. They are dominated by coniferous trees, such as hemlock, Douglas firs, pine and spruce. Mosses and lichens are also common. Animals include a wide range of slugs, ravens, blue grouse, Clarke's nutcrackers, bears, deer and coyotes.
Temperate grasslands are dominated by grass. They are found in South Africa, North and South America, and parts of Europe and Asia. They have hot summers, cold winters and moderate amounts of rain. The soil is dark and fertile and held together by the rotting grassroots that provide food for living plants. Droughts, grazing by large mammals and fires limit other forms of vegetation. Some trees and flowers, however, grow in temperate grasslands. Animals found in temperate grasslands vary by location but include gazelles, dogs, horses, rhinos, mice deer, snakes, jack rabbits and predatory birds.
Coastal deserts exist in moderately cool to warm areas and have cool winters followed by long, warm summers. They have 3 to 5 inches of precipitation and a broad range of temperatures between 24 degrees F to more than 95 degrees F. Soil in the coastal deserts is finely textured, porous and moderately salty. Many of the plants in the coastal deserts have extensive root systems close to the surface that take advantage of infrequent rain showers. Several species have thick, fleshy stems or leaves that can store large amounts of water for future use. Animals of the coastal deserts include toads, coyotes, badgers, lizards, snakes and birds of prey.