Tuesday, June 28, 2011

Geographical variation and Biodiversity

Dry forests tend to exist north and south of the equator rain forest belt, south or north of the subtropical deserts, generally in two bands, one between 10° and 20°N latitude and the other between 20° and 30°S latitude. The most diverse dry forests in the world occur in southern Mexico and in the Bolivian lowlands. The dry forests of the Pacific Coast of northwestern South America support a wealth of unique species due to their dry climate. The subtropical forests of Maputo land-Ponderousin the sub-tropical regions of the United States of America and in southeastern Africa are diverse and support many endemic species. The dry forests of central India and Indochina are notable for their diverse large vertebrate faunas. Madagascar dry deciduous forests and New Caledonia dry forests are also highly distinctive (pronounced extremism and a large number of reliquary taxa) for a wide range of taxa and at higher taxonomic levels. Trees use underground water during the dry seasons.


Species tend to have wider ranges than moist forest species, although in some regions many species do display highly restricted ranges; most dry forest species are restricted to tropical dry forests, particularly in plants; beta diversity and alpha diversity high but typically lower than adjacent moist forests.

Effective conservation of dry broadleaf forests requires the preservation of large and continuous areas of forest. Large natural areas are required to maintain larger predators and other vertebrates, and to buffer sensitive species from hunting pressure. The persistence of riparian forests and water sources is critical for many dry forest species. Large swathes of intact forest are required to allow species to recover from occasional large events, like forest fires.

Dry forests are highly sensitive to excessive burning and deforestation; overgrazing and exotic species can also quickly alter natural communities; restoration is possible but challenging, particularly if degradation has been intense and persistent. Degrading dry broadleaf often leaves thorny shrublands, thickets, or dry grasslands in their place.

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