Biodiversity and carbon storage co-benefits of coffee agroforestry across a gradient of increasing management intensity in the SW Ethiopian highlands

Abstract

Agroforestry has been proposed as a way to reconcile biodiversity conservation, food production and the delivery of other ecosystem services in tropical landscapes. One such a key ecosystem service, especially in the light of climate change mitigation, is carbon storage. Increasing human disturbance and management intensification, however, are known to affect the carbon storage potential of forests. Here we assessed how the above- and belowground carbon stocks in Ethiopian moist evergreen Afromontane forest co-varied with their biodiversity, and with increasing agroforestry management intensity for the production of Arabica coffee (Coffea arabica L.). We assessed above- and belowground carbon storage in 60 plots across a gradient of agricultural intensification ranging from natural forest, over two different coffee agroforestry systems, to intensified shade plantations. We quantified the diversity of ground beetles and woody plants in the same plots. Carbon stocks in natural forests (413±55.6S.E. Mgha⿿1) and in the most extensively managed agroforestry systems (387±50.0Mgha⿿1) were significantly higher than those in the more intensified agroforest system (258±39.4Mgha⿿1) and in shade plantations (219±22.8Mgha⿿1). Diversity of woody plants, but not of ground beetles, declined with increasing management intensity and decreasing carbon stocks. Overall, this study demonstrates that extensive coffee farming in Ethiopian moist Afromontane forests is able to deliver important co-benefits in terms of woody plant species conservation and carbon storage. Given the associated coffee yield cost, it is most likely, however, that supporting payments from certification or policy mechanisms such as REDD+ are required to keep these extensive coffee agroforestry systems economically viable, which is required to avoid management intensification and associated carbon and biodiversity losses.