Documenting six decades of change in herpetofauna occurrence patterns in a mountain ecosystem.

High-quality distribution data are essential for conservation planning but, are often scarce for mountain ecosystems. We integrated six decades of published and unpublished distribution records of herpetofauna from a mountain national park in Romania, and assessed the spatiotemporal patterns in species occurrences and consequent challenges for conservation. The number of records significantly differed from the expected values, based on the proportion of the area of altitudinal domains. We documented species richness, ranges and habitat changes across the park. Richness was lower in peripheral regions, with stable or expanding populations concentrated in the integral protection zone and the northwestern part of the buffer zone. Declines of introduced trout from alpine lakes facilitated recolonization by amphibians, while man-made structures, the spread of other species (e.g. Bufo bufo, Podarcis muralis, Zootoca vivipara). We emphasize the need for robust monitoring programs for herpetofauna in mountain habitats, to reduce biases and accurately assess, understand, and predict the dynamics of species distributions. While the park is still well-preserved, the creation and restoration of aquatic habitats are recommended to support amphibian populations. Targeted conservation measures are vital to mitigate the impact of man-made structures and tourism in the more accessible areas that overlap amphibian and reptile hotspots.