THE RUBBER SHOWCASE IN SUMATRA

As with cocoa a combination of available land and centres with fairly dense population is a prerequisite for a boom. But in the case of rubber the boom has been far more progressive than that for cocoa due to 3 main factors. Firstly, Sumatra and Kalimantan islands were almost empty at the turn of the century with population density inferior to 5 inhabitants/km². It took time for migrants (mainly from neighbouring Java in the case of Sumatra) as well as indigenous population (local Dayak and Chinese migrants in Kalimantan) to conquest the vast central plains of Sumatra and Kalimantan. Secondly, however the demand was very strong and rubber prices very attractive, first planting have been physically limited by both distances and seeds availability. The main rubber cropping system has been the jungle rubber system based on the use of unselected seedlings. Seeds were collected in Estates, mainly located in North-Sumatra and West-Java, and then distributed or sold to farmers through networks of traders or missionaries. Another constraint was that seed production was limited to 1 month per year and seeds have to be planted within 4 weeks after harvest. Last, infrastructure and trade were not as developed in the first half of the century as they were in the second half when the cocoa boom occurred (in particular since the 1980's). Rubber has been immediately seen by local farmers as a very promising crop mainly due to its ability to be combined with the secondary forest regrowth in a complex agroforestry system called jungle rubber (Penot 2001). With unselected rubber seedlings (at no cost), no inputs (no fertilisers nor herbicide ..) and a very limited labour requirement for planting after upland rice, jungle rubber is very easy to implement as it does profit directly from the “forest rent” (Ruf 1987). The lack of capital requirement fo establishment and the very progressive migrations enable us to define jungle rubber as a typical indigenous agroforestry. Jungle rubber being very close to secondary forest in terms of bio-mass and structure, one can consider that jungle rubber do maintain the forest rent and create a sustainable and permanent “agroforest rent “. These areas were inhabited by Malayu close to rivers and Kubus people in the primary forests in Sumatra, and by dayaks peoples in in hinterland when the coasts were populated with Malayu, Banjar or Javanese peoples in Kalimantan. Harvesting time may not be adapted to recommended planting periods for rubber as harvest and climatic conditions differ significantly between North and South-Sumatra due to their respective position around the Equator. Indonesia is now the second largest producer behind Thailand.