Madagascar lowland forests

The Madagascar lowland forests are a tropical moist broadleaf forest ecoregion, found on the eastern coast of the island of Madagascar, the fourth largest island in the world, and home to a plant and animal mix that is 80 to 90% endemic, with the forests of the eastern plain being a particularly important location of this endemism.

Setting

The ecoregion constitutes a narrow strip of lowland forests between Madagascar's east coast and the mountainous central highlands, from sea level to 800 metres elevation. It covers an area of approximately 112,600 square kilometres. The ecoregion is under the direct influence of the moist southeast trade winds, which maintain a warm, humid climate.

The lowland forests extend from Marojejy in the north to the southeast corner of the island. At the northern edge of ecoregion around Vohemar, the moist forests transition to the drier Madagascar dry deciduous forests ecoregion. To the east, at approximately 800 metres elevation, the lowland forests transition gradually to the Madagascar subhumid forests ecoregion. The southern end of the ecoregion lies at the crest of the Anosyennes Mountains, where a narrow belt of dry transitional forest marks the transition to the xeric Madagascar spiny thickets ecoregion in the mountains' rain shadow.

Flora

The lowland forests are characterized by dense evergreen forests, 82% of which is endemic species, with a canopy exceeding 30 meters. Typical canopy species include Dalbergia, Diospyros, Ocotea, Symphonia, and Tambourissa; emergents of Canarium, Albizia, and Brochoneura acuminata rise above the canopy. The lowland forests have a rich diversity of Pandanus, bamboo, and epiphytic orchid species. At higher elevations the trees become shorter and have a denser undergrowth.

Fauna

The lowland forests represent a great reservoir of diversity and endemism. Nearly all of Madagascar's endemic mammal genera are represented there, including all five families of lemurs. Fifteen species and subspecies of lemurs are endemic and near-endemic to the ecoregion, including the aye-aye (Daubentonia madagascariensis), the hairy-eared dwarf lemur (Allocebus trichotis), both species of ruffed lemurs (Varecia variegata, V. rubra), the indri (Indri indri), the eastern woolly lemur (Avahi laniger), the diademed sifaka (Propithecus diadema), Milne-Edwards' sifaka (P. edwardsi), the golden bamboo lemur (Hapalemur aureus), the greater bamboo lemur (Prolemur simus), the gray-headed lemur (Eulemur cinereiceps), the collared brown lemur (E. collaris), and the red-bellied lemur (E. rubriventer). As well as lemurs the forest are home to seven endemic genera of Rodentia, six endemic genera of Carnivora and several species of bat. Rare animals include the brown-tailed mongoose (Salanoia concolor). Of the 165 bird species found here 42 are endemic to the region, such as the rare red-tailed newtonia (Newtonia fanovanae). The forests are also home to 50 endemic reptiles and 29 amphibians such as the following list of chameleons and dwarf chameleons: Calumma gallus, Calumma cucullatum, Furcifer balteatus, Furcifer bifidus, Brookesia superciliaris, and Brookesia therezieni. The freshwater fish population is also unique.

A famous extinct species was Delalande's coua (Coua delalandei) which has not been seen since the 19th century.

Threats and preservation

Madagascar's lowland rainforests have been preserved generally better than the high central plateau, presumably due to historically less population density and longer distance to the capital city via marginal highway. There has been widespread slash-and-burn activity in the lowland rainforests, reducing certain forest habitat and applying pressure to some endangered species. Slash-and-burn is a method sometimes used by shifting cultivators to create short term yields from marginal soils. When practiced repeatedly, or without intervening fallow periods, the nutrient-poor soils may be exhausted or eroded to an unproductive state. These habitat loss impacts are especially significant because of the inherent biodiversity and high endemism of these rainforests. An interesting feature of these rainforests is the presence of Pachypodium habitats, often associated with xeric islands created by locally efficient drainage.

External links

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