- Madagascar subhumid forests
The Madagascar subhumid forests are a tropical moist broadleaf forest
ecoregion which originally covered most of the central highlands of the island ofMadagascar .etting
The Madagascar subhumid forests historically covered most of Madagascar's central highlands, above approximately 800 meters elevation on the east and above 600 meters elevation on the west. The ecoregion has an area of approximately 199,500 square kilometers (77,000 square miles). The highlands catch the wet northeast
trade wind s, while the areas to the south, west, and north lie in the drierrain shadow of the highlands. The subhumid forests are bounded by the humidMadagascar lowland forests along the coastal strip to the east, by theMadagascar dry deciduous forests to the north, northwest and west, and by the xericMadagascar succulent forests andMadagascar spiny thickets to the southwest and south. In four areas above 1800-2000 meters elevation, the subhumid forests yield to the montaneMadagascar ericoid thickets .Amber Mountain (Montagne d’Ambre), which lies near the northern tip of the island, contains a significant pocket of subhumid forest, surrounded at lower elevations by dry deciduous forest. The subhumid forests ecoregion also includes the disjunctAnalavelona andIsalo massifs to the southwest, surrounded by succulent forests at lower elevations.Flora
The original flora of ecoregion has been much altered by human use; extensive areas have been cleared for
agriculture , grazing, andrice cultivation, and someexotic species have been introduced. Pockets of closed-canopy evergreen forest still exist, as do open-canopywoodland s. Large areas are now covered bygrassland , but the extent to which the grasslands are the result of human intervention is still subject to debate. Significant areas have become desertified following extensiveslash-and-burn activity primarily from 1970 onward, as population pressures led indigenous peoples to seekagricultural production in increasingly unsustainable methods.The subhumid forests shelter several species with origins in the temperate southern hemisphere
Antarctic flora , including several species ofpodocarp s "(Podocarpus " and "Afrocarpus )," and "Takhtajania perrieri", from the primitive dicot familyWinteraceae .Fauna
The subhumid forests were formerly home to the island's distinct
megafauna . Madagascar's long isolation from other continents resulted in a very limited land mammal fauna, and the endemic mammal lineages, in particular thelemur s, adapted to fill certain niches. Giant lemurs, now extinct, were as large as adult gorillas. Several species ofelephant bird s "(Aepyornis)", giant flightlessratite s related to theostrich , also became extinct since the arrival of humans approximately 2000 years ago, including "Aepyornis maximus", the largest bird species ever to exist.History, conservation, and threats
Madagascar's high plateau forests have been altered more than the eastern rainforests or the western dry forests, presumably due to historically greater population density and proximity to the capital city of
Antananarivo ; moreover, there has been extensiveslash-and-burn activity by native peoples in the central highlands, eliminating most forest habitat and applying pressure to someendangered species . Slash-and-burn is a method sometimes used by shifting cultivators to create short term yields from marginal soils. When practiced repeatedly over a large scale area, or without intervening fallow periods, thenutrient poor soils may be exhausted or eroded to an unproductive state.External links
* [http://worldwildlife.org/wildworld/profiles/terrestrial/at/at0118_full.html Madagascar subhumid forests (World Wildlife Fund)]
Wikimedia Foundation. 2010.