The extensive degradation of natural systems caused by anthropogenic activities is a pressing global conservation concern. There is hope that some of the negative impacts caused by forest loss such as reduction of ecosystem services and loss of biodiversity may be offset by the regeneration of altered landscapes to secondary forests. However, the value of secondary forests to fauna is poorly understood. Past research has shown that responses of amphibians to the regeneration of secondary forest vary among species and studies. Some of this variation may be attributed to the presence or absence of particular landscape features, such as riparian zones, which may affect species recovery. For amphibians, riparian habitats are important thermal refugia, they provide breeding habitats, and can serve as important corridors for movement. While riparian zones have been shown to be fundamental to maintaining amphibian populations in matrix habitat, there has been little research on the riparian-upland gradient of species diversity over the course of secondary forest succession. In our study, we examine the differences in species richness among riparian and upland habitats in a chronosequence of secondary forest in two tropical lowland wet forest regions of Costa Rica.
We found an overall weak positive relationship between species richness and forest age. However, when we analyzed data from upland habitats and riparian habitats separately, we found differing results. There was a positive relationship between upland species richness and forest age, while no effect was found in riparian habitats. Riparian habitats maintain high species diversity in modified habitats and early successional stages of forests. In harsh landscapes, such as those generated as a result of land-use change, riparian zones may be especially crucial to maintaining amphibian populations by serving as a refuge for a variety of species.