Local and regional aspects of habitat quality jointly affect the biodiversity of ephemeral ponds

Background/Question/Methods

The biodiversity of local communities is likely affected by both local habitat quality and by the quality of the landscape surrounding the locality.  In pond environments, habitat quality within a pond may be affected by the kind of leaf litter present because leaf species differ in the kind of habitat structure they provide and the rate at which they release nutrients and energy into the water. The quality of the landscape surrounding a pond may also differ among landscapes (e.g., some landscapes provide a richer pool of potential colonists) which could also affect pond biodiversity.  We conducted a split-plot randomized block experiment to examine how both landscape and local scale properties affect biodiversity within temporary pond communities in eastern NC.  We manipulated both the kind of landscape in which artificial ponds were located (open-canopy grassland, pine forest, and hardwood forest) and the leaf species (sedge, pine, or maple) present in artificial ponds.  Ponds were open to colonization by amphibians and aquatic insects during the summer of 2010.  We surveyed organisms present in ponds on a monthly basis and did a complete census of each pond at summer’s end.  We present results from the monthly surveys.

Results/Conclusions

Leaf litter type significantly affected biodiversity, with more species in sedge treatments than pine or maple.  The kind of plant community (landscape) in which ponds were embedded also had strong effects on biodiversity: open-canopy landscapes supported nearly twice as many species on average than forested systems.  There was a trend for an interaction between landscape and litter type: the effect of litter type on species richness tended to be stronger in open-canopy landscapes.  Our results show that the quality of leaf litter affects community diversity in temporary ponds, a result which has never been shown previously.  In addition to providing insight into a fundamental question of why some locations are more diverse than others, our work provides insight into how human activity that changes habitat (and hence litter) type alters the biodiversity of pond communities, and it could shed light on whether particular kinds of habitat may require more conservation priority than others.