Deserts and xeric shrublands

Deserts and xeric shrublands also called xerófila are a biome characterized by, relating to, or requiring only a small amount of moisture,^[1] usually defined as less than 250 mm of annual precipitation. It is the largest terrestrial biome, covering 19% of the earth's land surface area.^[2] They may be further characterized as hyperxerófila (very dry) and hypoxerófila (less dry).

Character of the biome

Biodiversity

Deserts and xeric shrublands may have extraordinarily rich floras with very high alpha and beta diversity; reptile faunas may also be very diverse; local endemism may be quite pronounced in some regions.

Minimum resources

Many species track seasonally variable and patchy resources and require large natural landscapes to persist; water sources and riparian habitats are critical for the persistence of many species.

Poor soils

Because biomass productivity is low, the litter layer is almost nonexistent and organic content of surface soil layers is very low. Finally, evaporation tends to concentrate salts at the soil surface.

Sensitivity to disturbance

Highly sensitive to grazing, soil disturbance, burning, plowing, and other cover alteration; restoration potential can be very low and regeneration very slow; exotic species may be a serious problem.

Desertification

The conversion of productive drylands to desert conditions is known as desertification, and can occur from a variety of causes. One factor is human intervention in imposing intensive agricultural tillage or overgrazing^[3] in areas that cannot support such exploitation. Climatic shifts such as global warming or the Milankovitch cycle (which drives glacials and interglacials) also affect the pattern of deserts on Earth.

Desert and xeric shrublands ecoregions

See also

• Arid Forest Research Institute (AFRI)
• Xeriscaping- gardening or landscaping in xeric environments
• Xerophytes- plants adapted to xeric environments
• Shrub-steppe
• Temperate grasslands, savannas, and shrublands
• Sagebrush steppe
• Mesic
• Hydric

References

External links

• Deserts and xeric shrublands (World Wildlife Fund)
• Index to Deserts & Xeric Shrublands at bioimages.vanderbilt.edu
• Xeric World Online Community focused on the study of Xeric Plant Species.