Madagascar lowland forests

• Category: Forest Biomes.
• Geographic Location: Indian Ocean.
• Summary: One of the foremost ecoregions for species endemism, the lowland forests of Madagascar also represent one of the world’s most threatened terrestrial biodiversity hot spots.

Occupying a narrow slice of alluvial land running along the eastern edge of the world’s fourth-largest island, the lowland forest of Madagascar is among the world’s foremost regions for species endemism. A total of 80 percent of its flora and fauna exist here and nowhere else on Earth. The forest’s remarkable number of endemic species is evidence of the island’s unique evolutionary path, a product of its longtime isolation from the planet’s major land masses.

Madagascar sits in the Indian Ocean not far south of the Equator, 250 miles (402 kilometers) across the Mozambique Channel off Africa’s southeastern coast. One of the world’s most biodiverse and threatened ecoregions, it is the focus of international conservation efforts.

Along with the subhumid forests and scrub ericoid thickets, the lowland forests make up one of Madagascar’s three terrestrial ecoregions—and support more than half of the island’s species, many of which are endangered.

The lowland forests here fill a narrow, 30-mile-wide (48-kilometer-wide) strip of land between the east coast and the mountainous central highlands of Madagascar. The strip stretches from the southeastern tip of the island to Marojejy National Forest beyond Antongil Bay and Masoala Peninsula in the northeastern corner, covering an area of 43,500 square miles (112,664 square kilometers). Altitude of the forests ranges from sea level to more than 2,600 feet (792 meters).

Warmed by the moist southeastern trade winds of the Indian Ocean anticyclone, and nourished by a steady rainfall that averages more than 100 inches (2,540 millimeters) per year—sometimes even reaching up to 340 inches (8,636 millimeters)—this subtropical ecosystem is marked by moist broadleaf rainforests; closely spaced evergreen trees with wide trunks; hanging vines and lianas; and sparse vegetation on the forest floor, a result of sunlight being blocked by the thick canopy above.

Madagascar has two seasons: rainy and dry. During the rainy season, it experiences frequent thunderstorms, lightning, and sometimes destructive cyclones coming primarily from the Mascarene Islands to the east.

Biodiversity

The lowland forests are perhaps best known for having a remarkable rate of endemism among their plant, insect, reptile, and fish species, and in particular for 66 terrestrial mammalian species, all of which are endemic. Madagascar split from the African continent 150 million to 180 million years ago, and from the Indian subcontinent 88 million years ago, creating what various observers and researchers have called an “alternate world,” a “living laboratory,” a “world apart,” and the “seventh continent.”

The dense canopy of leaves and branches provides shelter for a wide variety of species, with 70 to 90 percent of them living above the forest floor, some as high as the treetops, at around 210 feet (64 meters). Important plant species here include rosewood or pea (family Dalbergia), persimmon and ebony (genus Diospyros), bamboo, and epiphytic orchids.

Notable among the high diversity of mammals are 100 species of lemur, all endemic, and considered by many scientists as a parallel clade to anthropoid primates. The Madagascar Lowland Forests biome also supports the highest diversity among the island’s birds, with 42 of the 165 breeding species recorded in these forests being endemic. Recently rediscovered species, which were previously thought to be extinct, include two lemurs and one bird: the hairy-eared dwarf lemur (Allocebus trichotis), golden bamboo lemur (Hapalemur aureus), and Madagascar serpent eagle (Eutriochis astur).

Effects of Human Activity

Once virtually covered by rainforests and other dense vegetation, Madagascar has lost 90 percent of its forests since humans arrived some 2,000 years ago. Around 70 percent of the forests were destroyed under French rule from 1895 to 1925. Since the 1970s, a third of the remaining forest cover disappeared, primarily due to clearance for coffee plantations; illegal logging; and slash-and-burn activity known locally as tavy. These practices have led to habitat destruction, river siltation, and widespread land degradation and erosion. This deforestation, much of which is irreversible, has pushed many of the region’s species to the brink of extinction.

Infrastructure on the island is poor. Notably, electricity is not available to rural communities. In the 2020s, the vast majority of people in rural areas relied on wood and charcoal as their primary energy source. Fuelwood reforestation is an ongoing effort as is development of and availability of more efficient cookstoves.

Hunting also threatens the survival of many species. Virtually all of Madagascar’s endemic animals and their unique habitats face serious threats. The nation has more critically endangered primates than any other nation in the world. Deforestation of the rainforests of Madagascar has potentially grave climate change impact, as the vegetation, when intact, very effectively helps absorb carbon dioxide. Cleared areas are slow to recover, however.

Madagascar is particularly vulnerable to climate change. The United Nations identified Madagascar as the fourth most vulnerable country in the world to climate change. Reoccurring droughts and cyclones already threaten the island, and the effects of climate change make those events longer-lasting and more intense. In 2020, Madagascar was facing its most serious drought in 40 years. A region of extremes, the island experienced intense cyclones in 2023, though this was not enough to combat how arid the land was after intense droughts. As climate change intensifies, the island may face more extreme variations in weather that could potentially upset the ecosystem.

Conservation Efforts

In recent years, significant efforts have been made to expand the nation’s protected areas. The Durban Vision, an initiative to increase the area of protection from approximately 6,500 square miles (16,835 square kilometers), or 3 percent of Madagascar’s total area, to 23,000 square miles (59,570 square kilometers), or 10 percent of the total area, was announced at the 2003 International Union for Conservation of Nature (IUCN) World Parks Congress in Durban, South Africa. As of 2022, areas receiving official state protection included five strict nature reserves, 21 wildlife reserves, and 25 national parks.

Bibliography

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