The relevance of cloud forest fragments and their transition zones for butterfly conservation in Taita Hills, Kenya

Abstract

A main driver of biodiversity loss is the transformation of pristine habitats into agricultural land, plantations of exotic trees, and settlements. The cloud forest of the Taita Hills in southern Kenya has suffered under such transformation processes. In consequence, remaining forests are small and isolated and often provide degraded forest habitats. We studied butterfly communities in four habitat types, cloud forest, cloud forest margin, exotic tree plantations, and agricultural land. We counted butterflies along transects during the rainy and the dry season. We assessed species traits for each butterfly species found. The four habitat types harbour distinct butterfly communities with only slight overlap among each other. Community compositions differed between the dry and rainy season. Forest specialist butterflies mainly occurred in the interior of the cloud forest, but were also observable along the forest edge. Species richness was highest at the transition between pristine cloud forest and agricultural land. The butterfly community of open agricultural landscapes was dominated by common and widespread East African savannah species, equipped with more elongated wings compared with those found inside the cloud forest. Exotic tree plantations showed a mixed butterfly species composition, consisting of many common and widespread savannah species, but also forest species with comparatively low specialization. In conclusion, typical cloud forest butterflies are on the need for intact cloud forest patches and cannot be compensated by surrogate habitats, such as exotic tree plantations.