Improved jungle rubber systems

The plains of Sumatra and Kalimantan (our study area) were scarcely inhabited at the turn of the 19th century, population density inferior to 4 inhabitants/km2, mainly relying on shifting cultivation of upland rice. The introduction of rubber by private dutch estates in the 1910's triggered a radical change in the landscape evolution but not in farmers practices, at least at the beginning. As estates adopted monoculture right from the beginning, trying to maximize rubber production, farmers saw and exploited immediately the possibility of growing rubber on a very extensive way by enriching their fallows (belukar in Indonesian) with unselected rubber seedlings that was available and free. Planting rubber during, or after, upland rice was a very marginal supplementary amount of work, with no risks and more important: no cost. Rubber used to grow with the secondary forest in a complex agroforestry system called "jungle rubber". Productivity was sufficient to raise a very incentive income however rubber taping occurs with a delay compared to rubber monoculture in estates. The advantages of jungle rubber are clear: no cost, no labour required for maintenance during immature period, income diversification with fruits, rattan, timber and other NTFP (non timber forest products) from the agroforest. Indirect benefits are environmental with soil conservation and rehabilitation of degraded lands. Estates began to raise their own research programme in the 1920's leading to the adoption of several important innovations, fertilization, weeding level, exploitation systems among them improved planting material, the clones, has been the most important in terms of yield. Meanwhile farmers began to produce several innovations, with no cost, called "endogenous innovations" such as planting in lines, a minimum weeding (once a year) ... mainly through the improvement of some rubber farming practices. At that stage as the aim was definitely to establish a rubber system minimizing capital and labour investment, farmers shifted from an "enriched fallow with rubber" to a real "complex rubber agroforestry system". The productivity of jungle rubber being low (500 kg/ha/year of rubber) compared to that of estates using clones (1500 to 2000 kg/ha/year), and after having completed the possibilities of endogenous innovation production, farmers began to be interested to include "external innovations" such as clones, fertilization and good tapping systems. Some who had access to clonal rubber in monoculture began also to develop innovations such as intercropping during immature period and planting of perennial trees (or selection of those from natural regeneration) such as fruit and timber trees creating therefore an "improved rubber based complex agroforestry system" where the original aim of improving the fallow has disappeared before the willingness to establish a real cropping system. These practices were still forbidden in rubber development project 5 years ago only. Population increase, land scarcity in some areas and other more productive crop opportunity force farmers to move to a more productive Rubber Agroforestry System (RAS). Research in agroforestry has been very recently focused on how to integrate indigenous knowledge with jungle rubber and external innovations to raise productivity conserving benefits of agroforestry practices in terms of environment and biodiversity