Pastures vs forests : do traditional pastoral activities negatively affect biodiversity? The case of amphibians communities

Over centuries traditional pasturing created a complex landscape structure, but few studies have compared amphibian communities in traditional pasture with those in natural landscapes. In our study we assessed the impact of traditional pasture use in the Pyrenean region of Irati Forest. We also evaluated the relative importance of wetland and landscape features for amphibians. During 2010 and 2011, we monitored 45 wetlands and recorded abiotic and biotic environmental variables and the features of the surrounding landscape. We recorded the occurrence of seven species of amphibians (Calotriton asper, Salamandra salamandra, Lissotriton helveticus, Bufo bufo, Alytes obstetricans, Rana pyrenaica and Rana temporaria); at least one amphibian was detected in 89% of wetlands. Both wetland and landscape features explained a significant amount variation of community structure. The composition of amphibian communities was strongly affected by the surrounding landscape, S. salamandra being associated with the most forested areas, while B. bufo and C. asper dominate the communities within pasture areas. Community richness was not significantly related to the cover of forest or to the pasture cover in the surrounding landscape. Furthermore richness did not peak at intermediate levels of forest cover or of the cover of pasture. Traditional pastoral activities do not reduce amphibian biodiversity compared to natural landscapes, and allow environmental heterogeneity that is needed for certain amphibians in mountain areas.