Segregate or integrate for multifunctionality and sustained change through landscape agroforestry involving rubber in Indonesia and China

Rubber (Hevea brasiliensis L.) production systems have conserved forest biodiversity in some parts of
Asia and are a threat elsewhere. A holistic view on these two sides of the coin is needed. The roles
planted trees and agroforestry play in the transformation of lives and landscapes depend on the stage of
“forest transition” and the spatial configuration, segregation or integration, of the landscape. “Forest
transitions” need to be understood at the level of the actual pattern of change, (one level up) at the level
of drivers of change, and (one level down) at the level of consequences for ecosystem goods and
services. To close the loop on a feedback mechanism, forest transitions also need to be understood at the
level of mechanisms that link desirable or undesirable consequences of changes in tree cover to the
drivers, providing positive or negative feedback. “Forest ecosystem services” can be partially fulfilled by
agroforests as a form of domesticated forest. We revisit the theoretical framing of agroforests as part of
forest transition and discuss a case study of the rise and decline of complex rubber agroforests in lowland
Sumatra (Indonesia), and the recent expansion of monoculture rubber in China replacing agoforestry
systems. Both cases indicate a complex of driving and conditioning factors, but also a current lack of
incentives to reverse the trend towards landscape segregation. Complex agroforests represent an
intermediate stage of intensification, between natural forest and homegarden, and may occupy an
intermediate stage in the way landscapes develop under the influence of land users and other
stakeholders. Although complex agroforests represent considerable value (biodiversity and carbon stocks)
of relevance to external stakeholders, incentive systems for the land users need to match these values,
otherwise these systems will disappear when more intensified and simplified tree crop systems take over.
Current analysis of the choices in land sparing versus land sharing, and segregation versus integration,
emphasize the convex or concave nature of the bi-functional tradeoff curves.