Madagascar Essay Example | Topics and Well Written Essays - 750 words

Madagascar - Essay Example The geology of Madagascar consists of a backbone of Precambrian rock running from north to south down the length of the island, forming the central highlands (Figure 1, see Appendix). To the east of the plateau, there is an abrupt escarpment, while in the west the highlands slope more gently down to the Mozambique Channel. There is a wide variety of soil types, as well as considerable variation in elevation; several large massifs reach more than 2000 m. The trade winds, which come from the southeast across the Indian Ocean, produce moderate to high levels of orographic precipitation as they encounter this topographic relief. As a result, the majority of rain falls on the eastern side of the island. The western region is under the rain shadow of the central mountains, and conditions gradually become hotter and drier towards the Mozambique Channel. During the austral summer the western region is subject to a monsoon regime that originates in the north and dwindles to the south (Goodman and Benstead, 29). Consequently, there is a double rainfall gradient over the island, declining from east to west on the one hand, and north to south on the other. The northeast of Madagascar is the wettest part of the island and the southwest is the driest. The combined effect of Madagascar's rainfall re... Even within relatively short distances, there is notable turnover in species and flora composition. In 1921, the French botanist Henri Perrier de la Bathie proposed a two-tiered hierarchical classification of the vegetation of Madagascar, which has served as the basis for most subsequent biogeographic work on the island (Fig. 2, see Appendix). The major contribution of this study was the division of Madagascar into two major floristic zones corresponding to different climatic conditions and structurally distinct vegetation types. The flore au vent (windward flora) was defined as the area that comes under the direct influence of the moist southeast trade winds. The windward flora was later equated with the Eastern region of Madagascar, which includes the non-deciduous vegetation of both the coastal lowland region and central highlands (Goodman and Benstead, 239). The flore sous le vent (leeward flora) was defined as the area influenced by the drying effects of the trade winds as they descend after having crossed over the central highlands. This zone includes the deciduous vegetation of the west. The leeward flora was later equated with the Western region of Madagascar (Goodman and Benstead, 240). The fundamental biogeographic distinction between the "wet" non-deciduous forests of the east and "dry" deciduous forests of western Madagascar has been supported by numerous studies of plant, invertebrate, and vertebrate distribution patterns. Simultaneously, WWF ecoregion model divides the Eastern floristic zone into three primary regions that correspond to broad altitudinal ranges: humid ("lowland") forest (0-800 m), subhumid ("moist montane") forest (800-1800 m), and ericoid thicket (roughly above 1800 m). The major ecoregions of the Western floristic zone are