|Agroforestry in the Pacific Islands: Systems for Sustainability (UNU, 1993, 297 pages)|
|3 Agroforestry in Melanesia: Case-studies from Papua New Guinea and the Solomon Islands|
On most of the larger islands of Melanesia, sufficient land and relatively low population densities allow for the practice of extensive agricultural systems within largely forested landscapes. Human settlement and use of these lands have caused a humanization, taming, or "agriculturalization" of the forest. Although there is variation from place to place, the basic agricultural strategy consists of felling or ringbarking some trees and clearing the underbrush while at the same time protecting selected tree species that will remain or be allowed to regenerate as part of the garden of deliberately planted short-term crops and domesticated trees.
In most cases, the debris from forest clearing is allowed to dry and is then burned before or during planting, although in some areas such as on the Great Papuan Plateau in Papua New Guinea (Schieffelin 1975), on the Weather Coast of Guadalcanal, and in the upper Wainimala River area of Tailevu Province, Fiji - burning is discouraged. The debris is allowed to decay around emergent crops, thus retarding soil erosion and enhancing the development of the soil structure and the accumulation of organic matter.
The trees that have been preserved usually have some utilitarian value, such as provision of fruits, nuts, edible leaves, medicines, or wood for special purposes; or trees may be left intact or not weeded out because they improve the soil (e.g., the leguminous Albizia falcataria) or serve as habitats for desired prey such as birds of paradise, pigeons, or flying foxes (fruit bats). When such favoured trees are left unfelled on new garden sites, they are often pruned or pollarded to open up the ground to sunlight, to add additional organic material to the soil, or to provide support for climbing or sprawling crops. Thus, the practice of the classic system of shifting cultivation of gardens in forest results not only in the maintenance of soil fertility on garden sites but also in the development of a humanized forest fallow that itself contains many trees of economic and cultural significance.
The case-studies of Melanesian agroforestry systems presented in this chapter and chapter 4 are drawn from research carried out in various parts of Papua New Guinea, the Solomon Islands, Vanuatu, and Fiji (see map p. 36); the studies illustrate the range of variation possible within this general pattern. Some of the examples described are from areas of relatively low population density (Nduimba Basin in the highland fringe of Papua New Guinea and, in chapter 4, Namosi and Matainasau in Fiji); others are from areas of fairly high density (Buma on Malaita in the Solomon Islands and, in chapter 4, Tanna in Vanuatu). Not included in the Melanesian case-studies, except by inference in the discussion of the highland fringe of Papua New Guinea, is a description of the intensive, quasi-permanent sweet-potato cultivation of the densely settled Papua New Guinea Highlands, where labour-demanding tillage in grasslands is an important aspect of cultivation. But even here, where the forest has largely been replaced by anthropogenic grasslands, trees remain significant. Groves of Casuarina provide wood for fuel and fencing and serve as a planted, soilenriching fallow; Ficus dammaropsis (the "highland breadfruit") provides edible leaves; planted Pandanus conoideus is important nutritionally at midelevations and also in forested areas; and Pandanus julianettii and P. brosimos, which grow spontaneously or as quasi-domesticates in the remaining high-elevation forests above the zone of cultivation, provide oil-rich nuts that are an important supplementary food.