¨       A biome is a complex of terrestrial communities that covers a large area and is characterized by certain soil and climate conditions and particular assemblages of plants and animals.

¨       Species vary in their adaptations to different conditions.

¨       An adaptation is an inherited characteristic that increases an organism’s ability to survive and reproduce.

v      spines on a cactus minimize water loss

v      desert rodents have adaptations in their kidneys that help conserve water

¨       Plants and animals also exhibit variations in tolerance.

¨       Tolerance is the ability to survive and reproduce under conditions that differ from their optimal conditions.

v      Plants and animals in the desert can tolerate temperatures that range from blistering hot to below freezing

Biomes and Climate

¨       The climate of a region is an important factor in determining which organisms can survive there.

¨       A microclimate is the climate in a small area that differs from the climate around it.

v      Certain streets in San Francisco are often blanketed in fog while the sun shines brightly just a few blocks away

¨       Two main components of climate-temperature and precipitation-can be summarized in a graph called a climate diagram.

The Major Biomes

¨       Ecologists recognize at least ten different biomes.

§         Tropical rain forest

§         Tropical dry forest

§         Tropical savanna

§         Desert

§         Temperate grassland

§         Temperate woodland and shrubland

§         Temperate forest

§         Northwestern coniferous forest

§         Boreal forest

§         Tundra

¨       Each of the biomes is defined by a unique set of abiotic factors-particularly climate-and a characteristic assemblage of plants and animals.

¨       There is often ecological variation within a biome.

Ø       Changes in microclimate caused by differences in exposure or elevation above sea level.

Ø       Local soil conditions or the presence of rock outcroppings.

¨       Although boundaries between biomes on a map appear to be sharp, there are often transitional areas in which one biome’s plants and animals become less common, whereas organisms of the adjacent biome become more common.

¨       The characteristics and locations of biomes relate to the patterns of global winds and ocean currents.

Other Land Areas

¨       Some areas do not fall neatly into the major biome categories.

Mountain Ranges

¨       Mountain ranges can be found on all continents.

¨       Abiotic and biotic conditions vary with elevation.

¨       Plants and animals change as you move up the mountain.

v      grasslands on the bottomàopen woodland pinesà

forest of spruce and conifersàwildflowers and stunted vegetation resembling the tundraàice fields occur at the peaks

Polar Ice Caps

¨       Icy polar regions border the tundra are cold year round

¨       Mosses and lichens are the limited vegetation there.

¨       In the north polar region, polar bears, seals, insects and mites are the dominant animals.

¨       In the south polar region, the dominant wildlife includes penguins and marine animals.