A global meta-analysis of the biodiversity and ecosystem service benefits of coffee and cacao agroforestry

摘要

In tropical regions, the extent of agricultural land is rapidly increasing at the expense of natural forest with associated losses of biodiversity and ecosystem services. Agroforestry has long been proposed as a more sustainable agricultural system, conserving biodiversity and ecosystem services, while providing significant local livelihood. In this context, cacao and coffee agroforestry is often regarded as more compatible with conservation of ecosystem integrity than cacao and coffee plantations. Using meta-analytical techniques and mixed models on data from 74 studies conducted across Africa, Latin America and Asia, a global quantitative synthesis was performed to assess the impact on biodiversity and on ecosystem services of (i) the conversion of natural forest into cacao and coffee agroforestiy and (ii) the further intensification of agroforest into cacao and coffee plantation. Forest species richness and total species richness were significantly lower in the more intensively managed than in the more natural land use categories. Response ratios showed that the decline in total species richness was higher when comparing agroforest with plantation (-46%), than when comparing forest with agroforest (-11%). Biodiversity responses to intensification differed between Asia and Latin America, and between different species groups. Response ratios showed that management intensification decreased provision of ecosystem services with 37% when comparing forest with agroforest and with 27% when comparing agroforest with plantation. Our data suggest that species richness decline follows a concave yield function whereas ecosystem service decline follows a more convex yield function. Finally, we identified knowledge gaps related to a conspicuous lack of studies in Africa, and a general underreporting of ecosystem services and environmental variables related to agricultural intensification