Both forest fragmentation and coffee cultivation negatively affect epiphytic orchid diversity in Ethiopian moist evergreen Afromontane forests

Abstract

The moist evergreen Afromontane forest of SW Ethiopia has become extremely fragmented and most of the remnants are intensively managed for cultivation of coffee (Coffea arabica), with considerable impacts on forest structure, biodiversity and ecosystem functioning. We assessed the effect of coffee forest management and forest fragmentation on epiphytic orchid diversity. We selected large and small intensively managed forest sites and compared their epiphytic orchid diversity with the diversity of natural unfragmented forest. We surveyed 339 canopy trees using rope climbing techniques. Orchid richness decreased and community composition changed, from the natural unfragmented forest, over the large managed forest fragments to the small managed forest fragments. This indicates that both forest management and fragmentation contribute to the loss of epiphytic orchids. Both the removal of large canopy trees typical for coffee management, and the occurrence of edge effects accompanying forest fragmentation are likely responsible for species loss and community composition changes. Even though some endangered orchid species persist even in the smallest managed fragments, large forest fragments are better options for the conservation of epiphytic orchids than small forests. Our results ultimately show that even though shade coffee cultivation is considered as a close-to-nature practice and is promoted as biodiversity conservation friendly, it cannot compete with the epiphytic orchid conservation benefit generated by large unmanaged moist evergreen Afromontane forests.