Singapore's vest-pocket park: a rainforest survives within sight of skyscrapers

Natural History, April, 2004 by Jamie James

In 1819 the English administrator and naturalist Thomas Stamford Raffles landed on what is now Singapore's main island, with a mandate to establish a colonial port. He found a population of about 150 Malay inhabitants and a tropical rainforest edged by pestilential swamps. Commerce and rubber planting soon transformed Singapore into one of the most profitable jewels in the crown of the British Empire. Today it is an independent nation of 4.1 million people and skyscrapers that soar from its city center.

Only a few slivers of rainforest survive within the 246 square miles of the main island. One such area is Bukit Timah Nature Reserve, which ranges across the highest hill (533 feet) in the interior. Although the reserve covers little more than 400 acres, its value to naturalists can only grow; as developing nations in Southeast Asia rapidly clear-cut their virgin forests.

In the Malay language bukit timah means "tin hill." The hill (bukit) is made of granite, however, so it's a good guess that the original name was Bukit Temak: temak is Malay for a species of gigantic Shorea tree, and someone may have applied that name loosely to the related species that grow on the hill. Part of the hill's claim to fame is that the English naturalist Alfred Russel Wallace began his historic study of Malay flora and fauna in and around it in 1854. He stayed at a Jesuit mission surrounded by logging camps, where, in just two months, he collected 700 species of beetle. He attributed his phenomenal success to the loggers, who left behind heaps of sawdust and rotting wood detritus that provided the insects with a veritable banquet.

The principal danger Wallace faced during his sojourn there was from tigers. As he wrote in his classic account The Malay Archipelago, "It was rather nervous work hunting for insects among the fallen trunks and old sawpits, when one of these savage animals might be lurking close by, waiting an opportunity to spring upon us." Almost as treacherous were the tiger traps, pits dug fifteen to twenty feet deep, which dotted the island.

According to Richard T. Corlett, an ecologist at Hong Kong University who has investigated the history of the reserve, Bukit Timah was probably subject to a degree of logging, as Wallace's writings imply, but it has been under some form of protection since at least 1848. That is not to say the forest has enjoyed uninterrupted tranquility. In 1942 the hill was on the front line of the battle for Singapore, one of the worst British defeats of the Second World War. The Japanese occupiers respected the reserve, however, bringing in Kwan Koriba, a botanist from Kyoto University, to oversee the island's parks. Some caves near the peak of Bukit Timah, which served as military depots during the war, are now grated over and offer safe roosts for bats.

The skirmishes at Bukit Timah since the war have been disputes about encroaching development. In 1986 a major highway was completed along the reserve's eastern perimeter, separating the area from the Central Catchment Nature Reserve, where the major remaining rainforest of Singapore lies. And granite quarrying nearby--another bone of contention--did not cease until the late 1980s.

In 1967, in their book The Theory of Island Biogeography, the ecologist Robert H. MacArthur and the biologist Edward O. Wilson of Harvard University proposed that the degree of biodiversity surviving in an island ecology is a function of the area of the island and its distance from the source of immigrating species. Those principles have been tested and confirmed for artificially created islands of primary habitat, as well as for landmasses actually surrounded by water. The rule of thumb is that an island reduced to one-tenth its original size will lose half its species.

By that standard, Bukit Timah is beating the odds. Although more than 99 percent of the original rainforest on the island of Singapore has been cleared, the reserve still retains nearly half the original native bird species and many small mammals.

But the large vertebrates have not been so fortunate. The island's last tiger was reportedly shot in the Choa Chu Kang district in 1930 (not, as local folklore would have it, in 1902 in the billiards room of the Raffles Hotel in downtown Singapore). The last one at Bukit Timah was killed in 1924 (the reticulated python has replaced the tiger at the top of the reserve's food chain). Other large mammals that have vanished are the leopard, the largest species of deer (the sambar and the barking deer), the pig-tailed macaque, and the wild pig. Some ecologists think that once the big vertebrates are gone, it is just a matter of time before the entire fabric of biodiversity unravels.

The loss of many native bird and mammal species from Bukit Timah can be traced to hunting and trapping, rather than to isolation and habitat degradation. That may sound like a dismal conclusion, but it speaks well, at least, for the potential of a small reserve to maintain the diversity of its fauna.