Western Madagascan BioProvince
With the exception of the southwestern areas this BioProvince (as defined by Armen Takhtajan) includes the western side of the Madagascar and the northern Diego-Suarez region. Two large basins of mid-Paleozoic to Recent sedimentary rocks make up much of the geology. The climate is subequatorial but drier than eastern parts mainly due to the fact that the trade winds lose their humidity by the time they reach this area. In fact, it occupies a rain shadow to the west of the central highlands and has a relatively long and pronounced dry season. The flora has a higher level of endemism than the moist eastern forests with many endemic genera and a multitude of endemic species. This mainly relates to the fact that the area's primary plant community of dry, deciduous forest is one of the World’s richest and most distinctive tropical forests. However, it is now badly fragmented and large areas have been converted to secondary grassland of little conservation interest. Most of these forests occur below the 800 m contour and although less species rich than the moist eastern forests, they have a very large and varied flora in which no single species or small group of species dominate. There are, however, very few vascular epiphytes, virtually no bryophytes, just a few lichens, and ferns and palms are absent. Species composition varies according to whether these forests occur on lateritic clay soils, sandy soils or calcareous soils.
The following accounts for this BioProvince have been written or will be written with particular reference to endemic and locally important species. Accounts available are displayed in green or yellow. Those displayed in red are either in the pipeline or awaiting expert contributions.
|Endemic Vascular Plant Flora|