Market constraints for commodities such as palm oil and rubber will curtail future expansion, and it seems unlikely that by the year 2000 such agricultural plantations could exceed 30 million hectares (10% of the remaining closed-forest area of the region). By contrast, the planting of perennial tree crops in settlement projects such as the Indonesia Transmigration program, in which there is a much higher degree of dependence on annual food cropping, are experiencing considerable problems. A high-priority area for the future is more intensive research and field-scale trials of new technologies for sustaining annual food cropping in the acid latosols (bleached red and yellow tropical soils) that underlie rain-forest lands. Particularly important are agroforestry techniques such as alley-cropping (a system of growing crops interspersed with lines of fast growing leguminous woody species), which can reduce dependence on artificial fertilizers, and zero tillage technology, which leads to the retention of organic matter in soil.
Another high-priority area for research is the food-cropping potential of the thousands of unresearched plants that grow within the tropical rain forests. Such research could help to widen the range of food crops available for indigenous consumption. A good example is the winged bean (Psophocarpus tetragonolobus). Although this plant has been known for centuries to the forest tribes of New Guinea, it was hardly recognized elsewhere. Research has demonstrated that the plant has a nutritional value equivalent to soybean (40% protein and 17% edible oil). It is now being cultivated for food production in some 50 developing countries.
Of the more than 200 potential timber species occurring in the natural forests of Asia, more than two-thirds are currently regarded as weed species of little commercial value. Intensive research and market promotion have done much to introduce some of the lesser known species to the market and could do much more. Between 1977 and 1981, for example, the utilization of lesser known species more than doubled in Peninsular Malaysia. They now account for 27% of the log intake of plywood/veneer mills.
Investment in more intensive natural forest management and, in particular, the establishment of compensatory plantations of fast-growing tree species can also help to take the pressure off natural forests. Species such as Gmelina arborea, Albizzia falcataria, Leucaena spp., and, in appropriate locations, Eucalyptus and Pinus caribaea grow at 4 to 5 times the rate of slower-growing indigenous forest trees. Fuelwood crops mature in 10 years, and timber, in 20 to 25 years, compared with 60- to 80-year rotations more typical of the natural forest species. All the needs for industrial wood in the region by the year 2000 could in theory be supplied from fast-growing plantations covering about 25 million hectares, i.e., less than 10% of the remaining forest area. In the region as a whole, about 2 million hectares of fast-growing industrial plantations have been established. Burma, Indonesia, and India have substantial ongoing programs. Malaysia, the Philippines, and Thailand are preparing for an increased rate of planting.
Support for social and agroforestry programs outside the forests can help to provide farmers and village communities with the fuelwood, poles, fodder, and