Impact of Stream Corridors on Breeding Populations of Rana luteiventris

Abstract

The biodiversity on Earth is in a state of decline. Because the full extent of the problem is not known, model systems are needed as environmental indicators. Amphibians are considered good indicators of wetland ecosystems. Many authors have agreed that a key factor driving population dynamics in a fragmented landscape is the ability of animals to move between habitat fragments. I studied the effects that a stream corridor has on the patch occupancy of breeding populations of western spotted frog (Rana luteiventris). I quantified landscape and habitat parameters in both Lump Gulch and Gravely Range landscapes. The Lump Gulch landscape consisted of wetlands connected by stream corridors, whereas the Gravely Range landscape consisted of glaciated kettle ponds, with no stream connectance. The area of wetland sites and the distance between sites did not have an influence on the patch occupancy of the different landscapes. By eliminating these factors my results suggest that stream corridors significantly influence the distribution of Rana luteiventris by providing a means to occupy and reoccupy wetland sites. In essence, the stream corridors between patches are precious resources and it is imperative that we preserve these habitats which are a means of dispersal across landscapes.