Terrestrial biomes

Biomes are terrestrial communities occurring over wide areas

Recognized by characteristic appearance
Associated with characteristic climates
Classified by vegetation

Distribution - Fig. 37.25 of biomes is a result of: Climograph

Climate - primarily determined by temperature and precipitation

Latitudes and altitudes

Richness of biomes

Tropical Rain Forests and Fig. 37.26

Richest biome in terms of number of species
Substantial rainfall throughout year

Competition great for sunlight; epiphytes and vines common

Savannas - image and Fig. 37.27 and Map

Reduced rainfall with prolonged dry seasons
Open grassland with scattered shrubs and trees
Maintained by periodic fires - fire adapted

Large herbivores and their predators dominate Food web

Deserts - Image and Fig. 37.28  Map

Extremely low rainfall
All great deserts at or near 30 degrees latitude N or S -
Other major deserts at continental interiors
Other deserts on leeward side of mountain ranges
Rain shadow effect: drier on leeward side of mountain

Both cold and hot deserts

Special adaptations by both plants and animals

Temperate Grasslands - Image and Fig. 37.29

Grasslands also called plains or prairies
Maintained by grazing
(large herbivores) and periodic fires or become forest - fire adapted

Most grasslands in US now converted to agriculture

Temperate Deciduous Forests - Image and Fig. 37.30   Map

Dominated by deciduous trees like oak, hickory, elm, maple, ash - lose leaves in winter
Moderate rainfall

Taiga or coniferous forests - also called boreal forests -Fig. 37.31

Northern coniferous forests of Eurasia and North America
Long, cold dry winters

Largest terrestrial biome

Very short growing season

Now being logged at a tremendous rate

Temperate Evergreen Forests - Image

Cool weather, dense fog, high precipitation

On coastlines as in northwestern U.S.

Large evergreens, many epiphytes

Very important timber - little old growth left

Tundra - Image and Fig. 37.32   Map

Bitter cold, high winds
Very low precipitation

Very short growing season
Permanent ice, permafrost,
underlying surface

Arctic (far north) and high mountains.

Chaparral - Image and Fig. 31.33

Spiny evergreen shrubs
Climate dry in summer   Map
Maintained by fire, needed for some seeds to germinate - fire adapted

Polar Ice and Fig. 37.34   Map

Ice caps at north (Arctic) and south (Antarctic) poles
No precipitation, fresh water scarce, life limited to coasts
Only bacteria, algae, small insects in Antarctic interior

Tropical upland forests and Fig 37.35   Map

Alternate wet (monsoon) and dry periods

Many trees lose leaves in dry period.


Semidesert Fig. 37.36   Map


Texas Ecoregions from Texas Parks and Wildlife