Madagascar and its neighboring island groups have an astounding total of eight plant families, four bird families, and five primate families that live nowhere else on Earth. Madagascar’s more than 50 lemur species are the island’s charismatic worldwide ambassadors for conservation, although, tragically, 15 more species have been driven to extinction since humans arrived.
The Seychelles, Comoros and Mascarene islands in the Indian Ocean between them support a number of Critically Endangered bird species. The Seychelles are also home to the only endemic family of amphibians: the Sooglossidae, and the Aldabra giant tortoise, one of the regions most heralded endemic reptiles.
A series of islands scattered in the western Indian Ocean off the southeast coast of Africa forms the Madagascar and the Indian Ocean Islands hotspot. Dominated by the nation of Madagascar, the fourth largest island on Earth, the hotspot also includes the independent nations of Seychelles (including Aldabra), the Comoros, Mauritius (including Rodrigues), and the French overseas departments of Réunion, Mayotte (one of the Comoros) and the Iles Esparses around Madagascar.
Because Madagascar and the continental Seychelles broke off from the Gondwanaland supercontinent more than 160 million years ago, the hotspot is a living example of species evolution in isolation. Despite close proximity to Africa, the islands do not share any of the typical animal groups of nearby Africa. Instead, they have evolved an exquisitely unique assemblage of species, with high levels of genus- and family-level endemism, in only 1.9 percent of the land area of continental Africa.
The natural vegetation of this hotspot is quite diverse. On Madagascar, tropical rainforests along the eastern escarpment and in the eastern lowlands give way to western dry deciduous forests along the western coast. A unique spiny desert covers the extreme south. The island is also host to several high mountain ecosystems such as Tsaratanana and Andringitra massifs, which are characterized by forest with moss and lichens. The Sambirano region, a northern transition zone between the western dry forest and the eastern rainforest that has
many of its own endemic species.
The Indian Ocean islands are composed of a range of relatively recent volcanic islands (the Mascarenes and the Comoros), fragments of continental material (the main group of the Seychelles), and the coral cays of the Amirantes and the atolls of the Farquhar, Cosmoledo, and Aldabra groups, as well as the five Iles Eparses. The volcanic islands have high peaks that in the recent past were covered by dense forest; indeed, the Comoros and the Mascarenes are sometimes subjected to very high levels of rainfall (up to 6,000 millimeters per year on Réunion). The highest peak in the Indian Ocean is the Piton des Neiges on Réunion (3,069 meters), which received the heaviest downpour on record (4.9 meters of rain in one week in 1980). By contrast, the continental Seychelles are relatively dry with a relatively low altitude reaching only 914 meters at its highest in Mourne Seychellois National Park.
Ironically, the isolation that allowed Madagascar and its neighboring islands to evolve a diverse and unique fauna and flora also contributed to its environmental degradation. Because humans did not arrive on the islands until 1,500-2,000 years ago, native animals were naïve and easily slaughtered by the colonists. The islands' location off the coast of Africa made them important stopping off points on trade routes and havens for pirates. On the Mascarenes, there is evidence to suggest that the extinction spasm of much of the native megafauna was directly related to hunting.
The Malagasy people came to Madagascar from Africa and Asia and imported agricultural methods, like rice cultivation, slash-and-burn agriculture, and cattle grazing, which are inappropriate for infertile, lateritic soils and devastating to the fragile ecosystems of the island. The central plateau of Madagascar is almost completely deforested - a lifeless moonscape of infertile, baked red earth. It is estimated that only about 17 percent of the original vegetation of Madagascar remains, with most remaining forests found along the eastern, western, and southern coasts. In the Comoros, which had the fourth highest deforestation rate in the world in the early 1990s (5.8 percent per annum), natural forests have been largely replaced with plantations, and the islands have lost at least 80 percent of their native vegetation. On the Seychelles, lowland forests have been cleared for timber production and agriculture, particularly for coconut plantations and cinnamon exploitation.
Mauritius has one of the highest human population densities in the world at 538 persons per square kilometer. In comparison, the nearly 18 million people who live in Madagascar today do not represent a very large number considering the land area of the island. However, the population is growing at more than 3 percent per year and is expected to double by the year 2025. In an area that is already one of the most economically disadvantaged in the world, this growth rate is putting tremendous pressure on the natural environment. In addition to agriculture, hunting and timber extraction, industrial and small-scale mining are growing threats.
On the other Indian Ocean Islands, these same threats have been exacerbated by the introduction of invasive alien species, brought as food sources, pets, or for pest control. Rats, cats and mongooses have devastated populations of birds and small reptiles, while grazing rabbits, goats, pigs, and deer have denuded many landscapes. In addition, exotic plant species such as water hyacinth ( Eichhornia crassipes) threaten the biodiversity of freshwater ecosystems in the hotspot.
conservation action and protected areas
In Madagascar, the government is beginning the third phase of its national Environmental Action Plan, with an ambitious five-year program of conservation and sustainable management activities. Today, about 2.7 percent of Madagascar's land area (16,131 km²) is officially protected in 46 legally protected areas, including national parks, strict nature reserves established to conserve ecosystems and special reserves designed to protect a particular species or a group of species. At the World Parks Congress in September 2003, the president of Madagascar, Marc Ravalomanana announced plans to triple protected area coverage over the next five years and asked for $50 million in assistance from the international community to do so. In the first six months following this announcement, $22 million in commitments were pledged by international and local conservation organizations, international development agencies, multilateral development banks and national governments to a Biodiversity Trust Fund that was created in January 2005.
In 2001, Birdlife International identified 141 Important Bird Areas (IBA) covering about 54,806 km² within the Madagascar and the Indian Ocean Islands Hotspot. More recently, Conservation International and other partners in Madagascar expanded upon this work to identify a total of 132 Key Biodiversity Areas based on the distribution of globally threatened species covering eight taxa: mammals, birds amphibians, reptiles, freshwater fish, arthropods, gastropods and plants. Many of the Key Biodiversity Areas have been identified as potential conservation sites for tripling the protected area network in Madagascar.
These activities to identify and safeguard the hotspot's remaining natural habitats are being implemented hand-in-hand with projects that maximize and demonstrate the value of this conservation to the country. For example, in much of Madagascar the watershed value provided by conservation of the remaining forests is of enormous economic value to the surrounding countryside. In some Key Biodiversity Areas, ecotourism has provided a viable source of income for local communities, such as through the famous guides association in Andasibe, near Perinet (Analamazaotra) Special Reserve.
On the other Indian Ocean Islands, significantly less natural habitat is designated for protection, although the few protected areas that do exist represent almost the entirety of remaining natural habitat on the islands, with the exception of the Comoros. (Not true for the Comores) There are about 208 km² of terrestrial protected areas in the Seychelles (46 percent of the land area, including two World Heritage Sites), while Rénion has 21 protected areas totaling 231 km². Although the Comoros currently have no terrestrial protected areas, there is a plan under development to establish three terrestrial national parks, in Mount Karthala on Grand Comore, Ntringui in Anjouan and on Moheli, as well as two additional marine national parks to complement that already existing on Moheli.
Efforts at species-focused conservation represent important progress for the future of several unique species. A number of lemur species have been bred successfully in captivity, and, in 1997, the first lemur reintroduction program introduced captive-born black and white ruffed lemurs ( Varecia variegata, EN) into the Betampona Nature Reserve. There are very successful combined captive breeding and community conservation programs for several species of tortoise. The Indian Ocean Islands also boast a number of threatened bird species that have been recovered from certain extinction: the pink pigeon ( Streptopelia mayeri, EN), Mauritius parakeet ( Psittacula eques, CR), Mauritius kestrel ( Falco punctatus, VU), Rodrigues fody ( Foudia flavicans, VU), Seychelles warbler ( Acrocephalus sechellensis, VU), and Seychelles magpie-robin ( Copyschus sechellarum, CR).
Evergreen fire-dependent shrublands characterize the landscape of the Cape Floristic Region, one of the world's five Mediterranean hotspots. Home to the greatest non-tropical concentration of higher plant species in the world, the region is the only hotspot that encompasses an entire floral kingdom, and holds five of South Africa’s 12 endemic plant families and 160 endemic genera. The geometric tortoise, the Cape sugar-bird, and a number of antelope species are characteristic of the Cape Floristic hotspot.