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Abstract:

Agroforestry is 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. In this study we assessed how carbon stocks in Ethiopian Afromontane forests co-varied with their biodiversity, and with increasing management intensity for the production of Arabica coffee. We also broadened our scope to the whole landscape and assessed the biodiversity conservation and carbon storage potential of all land uses. We quantified above- and belowground carbon stocks across a gradient of agricultural intensification ranging from natural forest, over two different coffee agroforestry systems, to intensified shade plantations. Ground beetle and woody plant diversity was defined based on the same plots. We found that carbon stocks in natural forests (413 ± 55.6 Mg ha-1) and in the most extensively managed agroforestry systems (387 ± 50.0 Mg ha-1) were significantly higher than those in the more intensified agroforest system (258 ± 39.4 Mg ha-1) and in shade plantations (219 ± 22.8 Mg ha-1). Diversity of woody plants, but not of ground beetles, declined with increasing management intensity and decreasing carbon stocks. The carbon account of the 106 ha studied landscape window emphasized the importance of non-forest land uses, storing 80% of the total carbon stock. Agroforests were found to harbour almost half of all encountered native tree species. To keep these extensive land use systems economically viable, which is required to avoid management intensification and associated carbon and biodiversity losses, we advocate payments for ecosystem services (PES) at the landscape scale.