The ecoregions of Madagascar, as defined by the World Wildlife Fund, include seven terrestrial, five freshwater, and two marine ecoregions. Madagascar's diverse natural habitats harbour a rich fauna and flora with high levels of endemism, but most ecoregions suffer from habitat loss.
Madagascar belongs to the Afrotropical realm. With its neighboring Indian Ocean islands, it has been classified by botanist Armen Takhtajan as Madagascan Region, and in phytogeography it is the floristic phytochorion Madagascan Subkingdom in the Paleotropical Kingdom.[ citation needed ] Madagascar features very contrasting topography, climate, and geology. A mountain range on the east, rising to 2,876 m (9,436 ft) at its highest point, captures most rainfall brought in by trade winds from the Indian Ocean. Consequently, the eastern belt harbours most of the humid forests, while precipitation decreases to the west. The rain shadow region in the southwest has a sub-arid climate. Temperatures are highest on the west coast, with annual means of up to 30 °C (86 °F), while the high massifs have a cool climate, with a 5 °C (41 °F) annual mean locally. Geology features mainly igneous and metamorphic basement rocks, with some lava and quartzite in the central and eastern plateaus, while the western part has belts of sandstone, limestone (including the tsingy formations), and unconsolidated sand. [1]
Seven terrestrial ecoregions are defined by the World Wildlife Fund for Madagascar. They range from the very humid eastern lowland forests to the sub-arid spiny thickets in the southwest. [2]
| Ecoregion | Biome | WWF code | Map | Image |
|---|---|---|---|---|
| Madagascar lowland forests or Madagascar humid forests | Tropical moist broadleaf forest: specifically seasonal (monsoon) tropical forest | AT0117 |  |  |
| Madagascar subhumid forests | Tropical moist broadleaf forest | AT0118 |  |  |
| Madagascar dry deciduous forests | Tropical dry forest | AT0202 |  |  |
| Madagascar ericoid thickets | Montane shrubland | AT1011 |  |  |
| Madagascar spiny thickets or Madagascar spiny forests | Xeric shrubland | AT1311 |  |  |
| Madagascar succulent woodlands | Xeric shrubland | AT1312 |  |  |
| Madagascar mangroves | Mangroves | AT1404 |  |  |
Freshwater ecoregions correspond to major catchment areas with a distinctive assemblage of species. In Madagascar, five ecoregions are distinguished:
The seas around Madagascar are part of the Western Indian Ocean province in the Western Indo-Pacific realm. They are divided into two marine ecoregions: [8]
The Sahara desert, as defined by the World Wide Fund for Nature (WWF), includes the hyper-arid center of the Sahara, between latitudes 18° N and 30° N. It is one of several desert and xeric shrubland ecoregions that cover the northern portion of the African continent.
An ecoregion is an ecologically and geographically defined area that is smaller than a bioregion, which in turn is smaller than a biogeographic realm. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural communities and species. The biodiversity of flora, fauna and ecosystems that characterise an ecoregion tends to be distinct from that of other ecoregions. In theory, biodiversity or conservation ecoregions are relatively large areas of land or water where the probability of encountering different species and communities at any given point remains relatively constant, within an acceptable range of variation . Ecoregions are also known as "ecozones", although that term may also refer to biogeographic realms.
The Global 200 is the list of ecoregions identified by the World Wide Fund for Nature (WWF), the global conservation organization, as priorities for conservation. According to WWF, an ecoregion is defined as a "relatively large unit of land or water containing a characteristic set of natural communities that share a large majority of their species dynamics, and environmental conditions". For example, based on their levels of endemism, Madagascar gets multiple listings, ancient Lake Baikal gets one, and the North American Great Lakes get none.
The Madagascar lowland forests or Madagascar humid forests are a tropical moist broadleaf forest ecoregion found on the eastern coast of the island of Madagascar, 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. They are included in the Global 200 list of outstanding ecoregions.
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.
The Western Gulf coastal grasslands are a subtropical grassland ecoregion of the southern United States and northeastern Mexico. It is known in Louisiana as the "Cajun Prairie", Texas as "Coastal Prairie," and as the Tamaulipan pastizal in Mexico.
The East Sudanian savanna is a hot, seasonally dry tropical savanna ecoregion of Central and East Africa.
The Mediterranean Acacia–Argania dry woodlands and succulent thickets is a Mediterranean forests, woodlands, and scrub ecoregion in North Africa centered mainly on Morocco but also including northwestern Western Sahara and the eastern Canary Islands.
The Southern Zanzibar–Inhambane coastal forest mosaic, also known as the Southern Swahili coastal forests and woodlands, is a tropical moist broadleaf forest ecoregion of eastern Africa. It is a southern variation of Northern Zanzibar-Inhambane coastal forest mosaic. The ecoregion supports habitats of forest, savanna and swamps. The southern portion of the ecoregion is not as well studied due to the 1977-1992 civil war in Mozambique.
Madagascar mangroves are a coastal ecoregion in the mangrove forest biome found on the west coast of Madagascar. They are included in the WWF's Global 200 list of most outstanding ecoregions.
Poland is part of four terrestrial ecoregions, one freshwater ecoregion, and one marine ecoregion.
The flora of Madagascar consists of more than 12,000 species of plants, as well as a poorly known number of fungi and algae. Around 83% of Madagascar's vascular plants are found only on the island. These endemics include five plant families, 85% of the over 900 orchid species, around 200 species of palms, and such emblematic species as the traveller's tree, six species of baobab and the Madagascar periwinkle. The high degree of endemism is due to Madagascar's long isolation following its separation from the African and Indian landmasses in the Mesozoic, 150–160 and 84–91 million years ago, respectively. However, few plant lineages remain from the ancient Gondwanan flora; most extant plant groups immigrated via across-ocean dispersal well after continental break-up.
The Somali Acacia–Commiphora bushlands and thickets is a semi-arid tropical grasslands, savannas, and shrublands ecoregion in the Horn of Africa. It is home to diverse communities of plants and animals, including several endemic species.
The Western Congolian forest–savanna mosaic is an ecoregion of Angola, Democratic Republic of the Congo, Republic of the Congo, and Gabon.
The Southeast Australia temperate forests is a temperate broadleaf and mixed forests ecoregion of south-eastern Australia. It includes the temperate lowland forests of southeastern Australia, at the southern end of the Great Dividing Range. Vegetation ranges from wet forests along the coast to dry forests and woodlands inland.
The Southern New Guinea freshwater swamp forests is a tropical moist forest ecoregion in southern New Guinea. The ecoregion includes the extensive swamp forests of southern and western New Guinea.