Economic outcomes of rubber-based agroforestry systems: a systematic review and narrative synthesis

A systematic review was conducted to examine expected economic outcomes of rubber-based agroforestry systems during mature rubber stage in comparison with monoculture rubber farming. Twelve studies were identified for a narrative synthesis of economic outcomes of the mature rubber production systems. The review found that whilst monoculture rubber production may produce higher income in some cases, particularly when rubber prices are high, profitable diversified rubber agroforestry systems were reported in all but one study. Rubber agroforestry has the potential to reduce the vulnerability of smallholders to volatile markets for rubber, particularly if the share of income from secondary species is substantial. Shade-tolerant crops with small canopies (e.g. coffee, bamboo and tea) are reported as ideal intercrops for rubber. Economically advantageous systems reported appeared to be rubber combined with species which provide additional income in the medium to long term (e.g. sheep and high value timber) and/or enhance ongoing cash flow with a lengthy productive lifespan and regular harvests (e.g. durian and gnetum). However, these systems are subject to many constraints such as labour availability, investment and management capacity and market conditions for secondary products. The review showed an absence of farm portfolio studies aimed at finding risk reducing enterprise combinations. Future research on economic outcomes of rubber agroforestry systems should firstly distinguish traditional jungle rubber from rubber agroforestry systems which use clonal rubber similar to those used in monoculture rubber, and secondly consider the full value of secondary products even if they are grown for own consumption.