Conservation embraces both the total protection of key areas (e.g., watersheds, rare/unique ecosystems, refuge of key animal/plant species) and the management of forests for the benefit of animals and plants as well as people. Forest clearance is the greatest threat to the survival of primates and many other animals, and to human welfare. For local and global environmental and economic welfare, close to 50% of tropical countries need to be kept forested; once the area dips below that proportion, climatic changes and water and soil problems seem to escalate catastrophically. Since few countries seem able to afford to keep more than 10% of their forests totally protected, the remaining 40% needed has to be managed for sustained yields of a wide variety of products. Managed forests provide a buffer zone for protected forests, which supply replenishment of plants and animals. The third part of the strategy is to use to maximum efficiency the land already cleared of forest or land that is so degraded that its role as forest cannot be redeemed.
Selective logging represents the compromise between human and animal needs in the long term, but it will only work if timber extraction is very light and carefully controlled. Even if only 10 trees/2.5 ac (1 ha) are extracted, 4% of trees and 45% of the total stand (68% of plant biomass) are damaged during access, felling, and extraction. It is the larger and more frugivorous species that are the most vulnerable, but their populations should recover fully within 20-30 years, if there is no further interference. Such logging enhances the diversity of microhabitats characteristic of the mosaic of succeeding successional stages of climax forest; it is these colonizing plants of immature forest that provide more nutritious, less chemically defended foods. The persistence of primary forest in an area may be crucial to the survival of certain animal species. In contrast to the tolerance of gibbons and langurs, orangutans and proboscis monkeys are seriously affected by selective logging.
Shifting cultivation has been practiced for centuries, especially along rivers, with peoples living in harmony with the forest, since the forest has recovered by the time people return. Increased population and less forest mean that return time is so reduced that this practice is no longer sustainable.
The loss of income from timber through reduced (sustainable) logging has to be balanced (easily exceeded in the long term) by income from other forest products. The exploitation of such forests can be maximized through knowledge of key animal-plant relations promoting the regeneration of such resources. The target has to be less damage to the forest and more produce on a sustainable basis. What is needed is the improved protection of watersheds and national parks representing all ecosystems, especially the richest, lowland ones, with the efficient, sustainable management of large buffer zones, and the more productive use of land already cleared of forest. Such a strategy should ensure that viable popula tions of all gibbon taxa survive in perpetuity, though it will not be easy.
The predictions of a drastic reduction in gibbon populations are being realized, but, as the clear-felling of forest declines, their prospects are boosted as long as adequate selectively logged forest persists, since gibbons have shown themselves to be very adaptable to such disturbance. The moloch, Kloss, pileated, and crested gibbons would seem to be the taxa most threatened with extinction, i.e., those with the most restricted and threatened ranges. No taxon is safe, however, from the extensive deforestation and other illegal activities that are currently rife throughout the Asian region. The larger mammals, with the greatest need for space, are the most vulnerable. Increased efforts by habitat countries, along with international support maintain extensive areas of forest for protection and sustainable management, may succeed. However, pressures from the human populations with their serious survival problems are understandably immense.
Captive breeding worldwide provides invaluable publicity of the plight of rainforest animals and education, including fundraising opportunities for conservation activities. It also helps to conserve the gene pool, by using meticulous stud-books. The prospects of reintroduction to the wild habitat are gloomy, given the costs involved and the lack of available habitat. However, a French nongovernmental organization (NGO), Eco-Passion, and facilities are being developed in Indonesia to accommodate confiscated gibbons, to form pairs, and, when ready, to reintroduce them to protected forest. If habitat is available, it is much more cost effective and successful to translocate social groups from doomed forest fragments to any under-stocked protected forest.
Little progress has been made in developing techniques of translocation, presumably because of the physical difficulties involved and the lack of empty suitable habitat. It remains a possible solution where populations become critically endangered, but adequate preparation, care (with veterinary supervision), and monitoring are essential. The prime effort must be to protect natural habitat and to conserve wildlife within it. It has yet to be determined to what extent costly captive breeding (at home or abroad), with research on nutrition and breeding, is necessary to boost populations.
Education is essential at various levels, as successful programs in many countries demonstrate, including Rwanda, Brazil, Peru, Costa Rica, and Indonesia. Most critical, however, is the need to influence the governments of tropical countries and, more importantly, the governments of "user countries" as well as the heads of international and national commercial concerns. Policy and activities must change rapidly, to avert impending catastrophes.
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