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Indo-Malay > Tropical and Subtropical Moist Broadleaf Forests >
Borneo lowland rain forests (IM0102)

Borneo lowland rain forests
Kalimantan (Borneo), Indonesia
Photograph by © WWF-Canon/Siegfried WOLDHEK


Southeastern Asia: Indonesia and Malaysia
Tropical and Subtropical Moist Broadleaf Forests

165,100 square miles (427,500 square kilometers) -- about the size of California and Vermont combined

· Large and Small
· Special Features
· Did You Know?
· Wild Side
· Cause for Concern
· More Photos

Large and Small

Step into the lowland forests of Borneo and you'll soon realize that you're in one of the richest rain forests in the world. Here you'll find some amazing contrasts: the world's smallest squirrel--the chipmunk-sized pygmy squirrel--and Asia's largest land mammal, the Asian elephant. You may see endangered orangutans swinging through the trees and Sumatran rhinos wallowing in mud holes. And if you notice a strong odor that smells like rotten meat, you’ve probably come across the flower of a plant called Rafflesia arnoldii. At more than 3 feet (~1 m) in diameter, this is the world's largest flower.

Special Features Special Features

All of Borneo, Java, Sumatra, and mainland Malaysia and Indochina were part of the same landmass during the Pleistocene glacial period. Land bridges between these islands allowed plants and animals (including humans) to migrate from one region to the next. Today, Borneo is separated from the other islands, but it continues to share similar plant and animal diversity. This ecoregion has a stable climate, with monthly rainfall exceeding 8 inches (200 cm) year-round and temperatures that rarely fluctuate more than 18° F (10° C). These conditions provide an ideal growing environment for the estimated 10,000 plant species found within the ecoregion's boundaries. Scientists have catalogued as many as 240 different tree species in a single hectare of the Borneo Lowland Rain Forests.

Did You Know?
Orangutans know where a large number of fruit-bearing trees are in the forest and when each one’s fruit will be at peak ripeness. With that knowledge, they move efficiently through the forest and always have the best fruit to feast on.

Wild Side

Home to 13 species of primates and 380 species of birds, the Borneo Lowland Forests are a hotspot of biodiversity. By day, orangutans and pig-tailed macaques (monkeys) swing through the trees feeding on fruit, while bearded pigs and Bornean yellow muntjacs (small deer) browse on leaves below. Birds called white-rumped shamas fill the air with melodious calls, and reptiles and amphibians scurry and hop in the undergrowth. As night approaches, flying squirrels and flying foxes (fruit bats) emerge from their daytime roosts. Mammals called pangolins search for ants on the forest floor, while civets and clouded leopards stalk their prey. The tarsier, a strange-looking primate with huge eyes, also appears at night in search of smaller animals and leaves. Birds of these forests include 8 hornbill species, 18 woodpeckers, and 13 pittas. Among the many reptiles are crocodiles, the false ghavial, and the earless monitor lizard, which spends most of its life in underground caves.

Cause for Concern

More than half of the natural habitat of this ecoregion has been lost or degraded. Commercial logging and the conversion of natural forests to oil palm, rubber, and industrial timber plantations present serious threats. These land-use changes have also increased the prevalence and destructiveness of fires. Despite the presence of several protected areas, scientists believe that the entire lowland forest of Borneo may be gone by 2010 unless drastic action is taken.

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

All text by World Wildlife Fund © 2001