The Madagascar subhumid forests are a tropical moist broadleaf forest ecoregion that covers most of the Central Highlands of the island of Madagascar. They are included in the WWF's Global 200 list of outstanding ecoregions. Most of the original habitats have been lost due to human pressure.
Geography
The Madagascar subhumid forests ecoregion covers Madagascar's highlands, which extend north and south along the length of the island, above approximately elevation on the east and above meters elevation on the west.
The Central Highlands is the largest highland region on the island, extending from approximately 16º to 23º south. The Central Highlands include Ankaratra and the Andringitra Massif, which is home to Pic Boby (2,658 m), the Central Highlands' highest peak.
The Northern Highlands includes the Tsaratanana Massif in the north, home to Maromokotro (2,876 m) Madagascar's highest peak, and the massifs of Marojejy to the northeast and Manongarivo to the northwest. It is separated from the Central Highlands by the Mandritsara Window, an east–west-running gap in the mountains with elevations below 800 meters.
The Southern Highlands include the Anosyenne Mountains and adjacent uplands in the southern part of the island. It is separated from the Central Highlands by the Menaharaka Window, another gap below 800 meters elevation, at approximately 23°S latitude. The highest peak in the Southern Highlands is Pic d'Andohahela at 1,959 meters.
The ecoregion includes some smaller outlying peaks, notably Montagne d'Ambre near the northern tip of Madagascar, the Makay Massif in west-central Madasgascar, and the Isalo and Analavelona massifs in the southwest of the island.
The subhumid forests extend to the northwest coast in the Sambirano region, including the island of Nosy Be. Most of that area is now covered by secondary grasslands and agriculture, with forest reduced to fragmented patches. The Sambirano region, also known as the Sambirano Domain, is a particular centre of endemism.
The ecoregion has an area of approximately . The highlands catch the wet northeast trade winds, and the eastern slopes generally receive more rainfall. The ecoregion includes the headwaters of most of Madagascar's rivers, and wetlands like Lake Alaotra. Areas to the south, west, and north lie in the drier rain shadow of the highlands. The subhumid forests are bounded at lower elevations by the humid Madagascar lowland forests along the coastal strip to the east, by the Madagascar dry deciduous forests to the north and west, and by the sub-arid Madagascar succulent forests and Madagascar spiny thickets to the southwest and south. In four areas above elevation, the subhumid forests transition to the montane Madagascar ericoid thickets.
Montagne d'Ambre near the northern tip of the island, contains a significant pocket of subhumid forest, surrounded at lower elevations by dry deciduous forest, as do Ankaratra, upland near Tsaratanana, Andringitra Massif, Ambohitantely Reserve, and the Ambohijanahary area. The subhumid forests ecoregion also includes the disjunct Analavelona and Isalo massifs to the southwest, surrounded by succulent forests at lower elevations.
Flora
The ecoregion is home to several distinct plant communities, which differ with elevation, rainfall, and soils. These include moist montane forest, sclerophyllous montane forest, tapia forest, rupicolous shrubland, and grassland.
The original flora of ecoregion has been much altered by human use; extensive areas have been cleared for agriculture, grazing, and rice cultivation, and some exotic species such as Acacia and Eucalyptus have been introduced. Moist evergreen forests are less susceptible to fire than the sclerophyll forests and ericoid thickets. Frequent human-set fires have transformed some of the ecoregion's former forests into savannas and grasslands. Grassland now coves much of the highlands, but the extent to which the grasslands are the result of human intervention is still subject to debate.