Plant biodiversity declines with increasing coffee yield in Ethiopia’s coffee agroforests

1. Tropical agroforestry systems provide farmers with resources for their livelihoods, but are also well recognized as refuges for biodiversity. However, the relationship between yield and biodiversity might be negative in these systems, reflecting a potential trade-off between managing for increased yield or biodiversity. The potential for synergies will depend partly on the shape of the biodiversity-yield relationship, where a concave relationship suggests a faster decline of biodiversity with increasing yields than a linear or convex shape. 2. We studied the relationship between biodiversity (plant species richness and composition) and coffee yield along a gradient of management in southwestern Ethiopia, coffee’s native range. We inventoried species richness and community composition of woody plants, herbaceous plants and bryophytes at 60 sites. We also measured coffee management-related variables and assessed coffee yield for three consecutive years at each site. 3. Species richness...