Near Tulear, Madagascar Photograph by David Whitacre   Afrotropics Deserts and Xeric Shrublands   17,100 square miles (44,300 square kilometers) -- about the size of Vermont and Massachusetts combined Critical/Endangered

· Isolated Wonders
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
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Isolated Wonders

The spiny deserts of Madagascar are stunningly beautiful and filled with amazing plants and animals. There is little shade here, and the impenetrable spiny thickets impede exploration, but a visitor here will be rewarded by the sight of bizarre and elaborate plant forms, all adapted to the harsh conditions of this dry climate. Madagascar is the fourth largest island in the world and has been isolated from mainland Africa for at least 150 million years. This prolonged isolation has led to the evolution of an extremely diverse assemblage of endemic plants and animals. For example, some 85 percent of the 12,000 species of flowering plants in Madagascar are endemic. And while the island of Madagascar is famous for its endemic biodiversity, the Madagascar Spiny Thickets ecoregion is absolutely astounding in that regard, with almost 100 percent of the plant species here found nowhere else. This high concentration of endemic species extends to animals as well, from the spider tortoise to the narrow-striped mongoose to five species of primates, including the ring-tailed lemur and the sifaka.

Special Features

The spiny thickets ecoregion is the driest area of Madagascar, with an average annual rainfall of less than 20 inches (500 mm). In the southwestern coastal area of this region, annual rainfall may be less than 14 inches (350 mm), and the dry season may last for 9 to 11 months. A wet season extends from October to April, but prolonged periods of drought are not uncommon. As a result, the plants of this region are highly adapted to dry, sandy soils and other harsh conditions. These adaptations include extended root systems that take in water from a wide area, enlarged trunks and branches that are able to store water, as well as spines, small leaves, and waxy and hairy coverings that inhibit water loss.

	Typical of the species richness and high rates of endemism found here, Madagascar boasts seven different species of baobab tree, six of them endemic, while continental Africa only has one species.

Wild Side

In the Madagascar Spiny Thickets, thick-trunked gray baobabs raise their gnarled branches to the sky. Baobabs are known as "upside-down" trees throughout Africa because their twisted branches resemble roots. Trees of the Didieraceae family are found only on Madagascar. These woody succulents have long, fleshy branches with water-storing cores. One Didiercaeae, the octopus tree, earned its name from upright branches that resemble the arms of an octopus. A rare lemur, called a sifaka, uses its long hind legs to spring from one branch to another and appears to fly as it soars gracefully through the air. On the ground, troops of ring-tailed lemurs feast on leaves from the bushy, drooping branches of tamarind trees. Rare birds such as the sub-desert mesite and long-tailed ground roller nest in dry tamarind thickets on sandy soils. Chameleons blend into their surroundings as boas slither across the forest floor in search of small vertebrates, occasionally venturing up into a tree in pursuit of birds. Yellow and brown spider tortoises, with shells reaching only four inches (10 cm) across, are among the smallest tortoises in the world. The endemic Grandidier’s mongooses sleep in burrows during the day, sheltered from the soaring heat. And at night, cat-like fossas creep quietly through the trees, ready to catch unsuspecting birds or lemurs by surprise.

Cause for Concern

Since the arrival of humans in Madagascar, more than 90 percent of the original forest has disappeared. Unfortunately, forest destruction on the island is continuing at alarming rates, and virtually all of the unique habitats and endemic animals of Madagascar are experiencing a significant level of threat. For example, Madagascar has more critically endangered primates than anywhere else in the world. Very little of the Madagascar Spiny Thickets ecoregion is protected. While the rate of habitat loss here is lower than in other habitats of Madagascar because of its lower human population density, recent developments such as an irrigation pipeline have increased the movement of people into the region. In the past, the taboos of local tribes kept them from hunting certain animal species such as lemurs. But with the influx of people today, these taboos are no longer enough to protect animals from over-hunting. Also, more and more people are entering the forests in search of trees for firewood and charcoal production. Selective logging for construction wood is also a grave threat, since the spiny thicket forest has a naturally slow rate of growth and regeneration. Other threats to the region include the increasing cultivation of corn, cattle and goat grazing, the spread of invasive plant species such as prickly pear and rubber vine, and illegal taking of reptiles, amphibians, mammals, and plants for international trade.

For more information on this ecoregion, go to the World Wildlife Fund Scientific Report.