ARE PERMANENT RUBBER AGROFORESTS AN ALTERNATIVE TO ROTATIONAL RUBBER CULTIVATION? AN AGRO-ECOLOGICAL PERSPECTIVE

摘要

Many rubber smallholdings in Indonesia have developed into rubber agroforests as a result of the extensive management of the plantation. The resulting complex multi-species agroforests have a number of environmentally beneficial characteristics including a high level of natural biodiversity. Most environmental benefits would be significantly enhanced if these systems were not taken periodically through a new cycle of slash-and-burn, as normally happens when latex yield drops to uneconomic levels. This paper explores, from an agroecological perspective, the potential for such cyclical systems to be developed into permanent agroforests providing sustained latex yield over a longer time frame without a slash-and-burn intervention. Evidence is providedfrom direct observations, interviews with farmers and the results of specific agronomic experiments. Enrichment planting of seedling or grafted-clonal rubber plants into existing rubber agroforests resulted in low growth rates as a result of shading fromcanopy trees and probably below-ground competition. Below-ground competition also probably continued to limit rubber growth at the sapling and pole stage within agroforests. High investment has to be made in physical protection to prevent mortality of planted rubber in agroforests due to wild pig damage. However, direct grafting of clonal buds onto naturally regenerated rubber seedlings within agroforests provides a potential technical alternative. It is concluded that, though technically possible, such development towards permanent forest cover implies a significant change in management strategy and is unlikely to develop spontaneously on a wide scale in the study area in Jambi Province, Indonesia.