Trumon And OrangUtan


Out-of-control illegal logging threatens the survival of the research station Suaq Balimbing, and its unique population of orangutans. What started on a modest scale in 1998, following the fall of President Suharto and the period of lax law enforcement that ensued, has now burgeoned into a large-scale illegal logging operation so far not stopped by the authorities. This development threatens the survival of a unique orangutan population. Together with similar processes elsewhere, these threats add up to jeopardize the viability of the species in the wild and the ecological functions provided by swamps.

Suaq Balimbing is located on Sumatra’s northwest coastal plain, part of the Leuser Ecosystem, the region in which a program funded jointly by the European Union and the Government of Indonesia is attempting to achieve conservation for sustainable economic development. The critical importance of the Leuser Ecosystem for conservation in Southeast Asia is widely recognized (see the attached brochure on the Leuser Development Programme).

Suaq’s swamp forest may be unappealing to the human visitor, but it harbors unique natural values. It has the highest observed bird and primate diversity in all of northern Sumatra, the highest primate biomass in all of Southeast Asia, contains unique species of fish and animals dependent on fish, and, perhaps most importantly, contains a unique population of orangutans. The orangutans at Suaq Balimbing occur at the highest recorded density, are far more sociable than those recorded elsewhere and have developed a unique, culturally transmitted, technology: they use tools, fashioned anew for each distinct task, to extract honey and insects from tree holes and extract highly nutritious seeds from a fruit protecting them with stinging hairs. Such tool use was suspected on the basis of work with captive animals, but so far unknown from the wild. We now know that culture-based technology is critically dependent on the proper environmental conditions, specifically those that facilitate social tolerance among the animals. Habitat degradation, such as that caused by logging, destroys the conditions maintaining technology in the population and will eventually lead to the extinction of their culture even if the animals themselves manage to survive.

The loss of the study area at Suaq Balimbing will extinguish this research, which is beginning to provide us with a glimpse into our own past. It will also put an end to a major educational effort. In the past five years, many students and scientists have used the facilities of the station. They hail from Indonesian universities (Universitas Indonesia, Universtias Siyah Kuala, Sekola Tinggi Kehutanan), as well as from universities in Great Britain, the USA, the Netherlands. Scientists from Australia, Brazil and the Czech Republic are also due to work at the station. Active field experience in the best sites is essential for the training of field ecologists and land managers.

Survey work and short-term studies of orangutans in other coastal swamps in the vicinity have also shown evidence for high densities and, at one site, tool use. Our studies indicate that the three main swamp areas on Sumatra’s west coast inside the orangutan’s distribution area harbor the world’s most important concentration of orangutans, with an estimated original total number of ca 5,350 individuals. By the end of 1998, we estimated that more than half the animals had been lost since the early-mid 1990s in an accelerating surge of forest drainage and conversion for plantation agriculture and of legal and illegal logging. Forest clearing for agriculture obviously obliterates orangutan populations. However, selective logging, leaving the land forested, also affects them. A single round of selective cutting reduces orangutan density to less than half, and continued timber removal drives the animals locally extinct. Most adult orangutans do not leave areas that are degraded; hence, many succumb to starvation and disease.

The orangutan, Asia’s only species of great ape and one of our closest living relatives, is now threatened with extinction. Occurring only in parts of Borneo and Sumatra, its numbers have dwindled to some 10% of those around the turn of the century. Current estimates by Rijksen, Meijaard and colleagues suggest that some 30,000 may still survive on Borneo, scattered over many isolated areas and many in populations of questionable long-term viability, whereas less than 10,000 are thought to remain on Sumatra, mainly in and around the Leuser Ecosystem. However, these estimates were made before the forest fires of 1997-98 devastated or affected several million hectares of forests on Borneo and before the recent wave of illegal logging swept the outer islands of Indonesia following the political upheaval of May 1998.

I would be remiss not to point out that in the continued lack of defense of formally protected areas, extrapolation of the current trends shows that in the coming decade most orangutan populations will become ecologically extinct (i.e. down to a small number of individual survivors), and that even the few major orangutan populations will be reduced to the point that their viability is in serious doubt. Thus, the prospects of orangutan survival are therefore increasingly dire.

Besides offering prime orangutan habitat or harboring many unique species, swamps also provide important ecological services. First, swamp forests capture Carbon, forming the most important terrestrial Carbon sinks. An actively growing peat swamp may sequester as much as 2 tons of C per ha per year, and thus may contain as much as 500 tons of Carbon per ha in each 1m-thick layer of peat. The peat in this region can be 8 m thick in places. Drainage and conversion of peat swamp forest leads to subsidence and a gradual loss of this accumulated Carbon due to oxidation to CO2, and thus contributes disproportionately to the greenhouse effect. Second, in many places swamps help to reduce water pollution, cleaning water as it passes through of both organic and inorganic loads, and provide buffer storage for excess water, thus lessening the impact of flooding on coastal towns and villages. Third, swamps greatly enhance the biomass of fishes in the river channels, and thus potential fish harvests near the mouth of these rivers, which are of importance to coastal communities. Finally, they have an effect on regional climate, tending to reduce the incidence of damaging droughts in areas further inland.

The Indonesian government has recognized the important functions of swamps for biodiversity and ecological services. Although the northernmost Tripa swamp has so far received no formal protection, most of the Kluet-Bakongan swamp is inside a National Park and most of the largest of all, the Trumon-Singkil swamp, has recently been declared a Protected Area. Unfortunately, at the moment protected status is meaningless. Illegal logging is taking place everywhere, endangering the viability of the reserves, and threatening to nip the incipient ecotourism industry in the bud. We must recognize these new realities. Urgent action is needed to avoid losing Leuser’s unique biodiversity and wild orangutans for good.

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