Urban forests and green spaces: Alternatives to maintain herpetofauna biodiversity in highly modified landscapes
Urbanization is the dominant trend in land-transformation worldwide replacing native habitat with anthropogenic systems where natural and human components interact. This powerful agent of ecological change on the landscape is associated to changes in species composition and in some cases species extinction. Puerto Rico is a densely populated island with little history of land use planning that sustains communities with high ecological value as a result of the high levels of endemism. Particularly, anuran and reptile are critical component of the island ecosystems and they are highly sensitive to spatial and temporal changes in habitat. These particularities make of Puerto Rico a valuable place to evaluate changes in herpetos biodiversity under different land-covers in an urban area. We selected 15 patches representing five (5) land covers (mature forest, young forest, shrubland, pasture, and yard) each one with three replicates. All those patches were located in the San Juan Metropolitan Area.
Between November 2011 and October 2012, 16330 individuals were observed. Mature and young forests contributed with about 51% of those observations. Twenty three of 25 potential species were recorded to the study area, 90.5% corresponded to native species. We also reported a new non-native snake species to the area. Herpetos richness trend to increase with more cover of woody vegetation while herpetos composition differed among covers. In general, reptiles had a higher richness (71%) than anurans in all covers but anurans were more abundant (56%) than reptiles, mainly in more forested areas. Results suggest that the herpetofauna assemblage structure among land covers is related with the habitat structure in each of them and with the availability and suitability of those habitats for the species. We propose that highly-modified anthropogenic areas could provide critical habitats and refuge for sensitive species, and they would play a critical role to maintain biodiversity.