Amphibian Diversity in the Matrix of a Fragmented Landscape Around Ranomafana in Madagascar Depends on Matrix Quality

Human-induced conversion of natural habitats into agricultural areas is one of the major drivers for biodiversity loss. In many tropical regions, the matrix habitat area (habitat between fragments of remaining natural habitat) considerably exceeds the area of the original habitat. Therefore, understanding the factors determining matrix quality for animals is a key step to guide conservation action in fragmented landscapes. Matrix habitat, although being often highly disturbed, might provide valuable habitat for some species, serves as buffer zone for remaining natural habitat or corridor between fragments, and hence could be an important component for biodiversity maintenance on a landscape scale. We evaluated the effects of matrix quality on frog diversity in a rainforest ecosystem in Eastern Madagascar. Although frog diversity was affected in all matrix habitats, we found that variation in matrix quality was an important factor. Matrix habitat could serve as valuable habitat and corridor (i.e., high frog diversity along streams in the matrix), as buffer zone (moderate diversity in banana plantations), or was unsuitable habitat for most frog species (very impoverished diversity in secondary vegetation and rice fields). The remaining natural vegetation in and outside protected areas in Madagascar and worldwide is decreasing and will not be sufficient to preserve its biodiversity on a long term. Therefore, we must understand responses of organisms to disturbance in order to create buffer zones and corridors combining both disturbed and natural habitats. Implementing corridors along matrix streams connecting forest habitats might be an important contribution to amphibian conservation in fragmented landscapes.