BiomesBiomes

•A biome is a large, distinctive A biome is a large, distinctive complex of plant communities complex of plant communities created and maintained by created and maintained by climateclimate..

8 biomes8 biomes: :

tundratundra taigataiga temperate deciduous foresttemperate deciduous forest scrub forestscrub forest (called chaparral in (called chaparral in

California) California) grasslandgrassland desertdesert tropical rain foresttropical rain forest temperate rain foresttemperate rain forest

The figure shows the distribution of these 8 biomes around the world.

Tundra

• The climate is so cold in winter that even the long days of summer are unable to thaw the permafrost beneath the surface layers of soil.

• Sphagnum moss, a wide variety of lichens, and some grasses and fast-growing annuals dominate the landscape during the short growing season.

• Caribou feed on this growth as do vast numbers of insects.

• Swarms of migrating birds, especially waterfowl, invade the tundra in the summer to raise their young, feeding them on a large variety of aquatic invertebrates and vertebrates.

Taiga

The taiga is named after the biome in Russia. It is a land dominated by conifers, especially spruces

and firs. It is dotted with lakes, bogs, and marshes. It is populated by an even more limited variety of

plants and animals than is the temperate deciduous forest.

In North America, the moose is such a typical member that it has led to the name: "spruce-moose" biome.

Before the long, snowy winter sets in, many of the mammals hibernate, and many of the birds migrate south.

Although the long days of summer permit plants to grow luxuriantly, net productivity is low.

Temperate Deciduous Forest

• This biome occupies the eastern half of the United States and a large portion of Europe. It is characterized by:

• hardwood trees (e.g., beech, maple, oak, hickory) which • are deciduous; that is, shed their leaves in the autumn. • The number of different species is far more limited than

in the jungle. • Large stands dominated by a single species are

common. • Deer, raccoons, and salamanders are characteristic

inhabitants. • During the growing season, this biome can be quite

productive in both natural and agricultural ecosystems

Temperate Rain Forest

• The temperate rain forest combines high annual rainfall with a temperate climate. e Olympic Peninsular in North America is a good example. An annual rainfall of as much as 150 inches produces a lush forest of conifers.

Tropical Rain Forest• In the Western Hemisphere, the

tropical rain forest reaches its fullest development in the jungles of Central and South America.

• The trees are very tall and of a great variety of species.

• One rarely finds two trees of the same species growing close to one another.

• The vegetation is so dense that little light reaches the forest floor.

• Most of the plants are evergreen, not deciduous.

• The branches of the trees are festooned with vines and epiphytes (see the photo taken in the Luquillo National Forest of Puerto Rico).

Epiphytes

• Epiphytes are plants that live perched on sturdier plants. They do not take nourishment from their host as parasitic plants do. Because their roots do not reach the ground, they depend on the air to bring them moisture and inorganic nutrients. Many orchids and many bromeliads (members of the pineapple family like "Spanish moss") are epiphytes.

Temperate Deciduous Forest

• This biome occupies the eastern half of the United States and a large portion of Europe. It is characterized by:

• hardwood trees (e.g., beech, maple, oak, hickory) which • are deciduous; that is, shed their leaves in the autumn. • The number of different species is far more limited than

in the jungle. • Large stands dominated by a single species are

common. • Deer, raccoons, and salamanders are characteristic

inhabitants. • During the growing season, this biome can be quite

productive in both natural and agricultural ecosystems

Grasslands

• Grasslands are also known as prairie or plains. The annual precipitation in the grasslands averages 20 in./year. A large proportion of this falls as rain early in the growing season. This promotes a vigorous growth of perennial grasses and herbs, but — except along river valleys — is barely adequate for the growth of forests.

Desert

• Annual rainfall in the desert is less than 10 in. and, in some years, may be zero. Because of the extreme dryness of the desert, its colonization is limited to

• plants such as cacti, sagebrush, and mesquite that have a number of adaptations that conserve water over long periods;

• fast-growing annuals whose seeds can germinate, develop to maturity, flower, and produce a new crop of seeds all within a few weeks following a rare, soaking rain.

Chaparral

• The annual rainfall in the chaparral biome may reach 20–30 in., but in contrast to the grasslands, almost all of this falls in winter. Summers are very dry and all the plants — trees, shrubs, and grasses — are more or less dormant then.

• The chaparral is found in California. (The photo shows the chaparral-clad foothills of the Sierra Nevada in California.) Similar biomes (with other names, such as scrub forest, are found around much of the Mediterranean Sea and along the southern coast of Australia.

• The trees in the chaparral are mostly oaks, both deciduous and evergreen. Scrub oaks and shrubs like manzanita and the California lilac (not a relative of the eastern lilac) form dense, evergreen thickets. All of these plants are adapted to drought by such mechanisms as waxy, waterproof coatings on their leaves.

• The chaparral has many plants brought to it from similar biomes elsewhere. Vineyards, olives, and figs flourish just as they do in their native Mediterranean biome. So, too, do eucalyptus trees transplanted from the equivalent biome in Australia.