Local turnover and factors influencing the persistence of amphibians in permanent ponds from the Saxon landscapes of Transylvania

Abstract. There is an increasing interest among ecologists and conservation managers in exploring the factors that influence the distribution and persistence of natural populations. In order to correctly assess the conservation status of a species, both local and landscape level studies are needed. Moreover, the temporal change in the habitat occupancy should be explored. In this paper we examine the turnover rate and explore the factors affecting the persistence of six amphibian species in 21 permanent (focal) ponds in the rural landscapes of Southern Transylvania (central Romania) over six years. The “patch model ” approach was used, meaning that amphibians, if present in the focal ponds were considered as local populations. The number of temporary ponds in the landscape positively influenced both the persistence of permanent pond populations (individual species) and the number of species that persisted continuously during the six years. Four species that were absent from the focal permanent ponds were present in ponds from the surrounding landscape. Roads and settlement cover were the most important variables negatively influencing the persistence of permanent pond populations. The regression models regarding the persistence of pond populations had a better fit if the population sizes were included in the model. The results of this study indicate that a high variability of interconnected ponds would increase the persistence of amphibian populations. We suggest that creating and maintaining a number of ponds without fish in the surroundings of permanent ponds will allow their use as refuges by amphibian species sensitive to fish predation, and therefore increase the persistence of local populations. Key words: amphibians; population turnover; patchy populations; landscape; Romani