No abstract

In many regions of the world, exotic or overabundant large herbivores are a concern for the conservation of forest plant communities. Previous work suggests that the impacts of white-tailed deer overabundance in North American forests are broadly negative. However, no quantitative synthesis currently exists to verify the generality or magnitude of these impacts. Using meta-analytical techniques, we show that white-tailed deer have strongly negative impacts on the diversity and abundance of forest understory plant communities, but these impacts are not ubiquitous for all components of the plant community. White-tailed deer have their largest impacts on woody plant species.

Abstract. Herbivores modify their environment by consuming plant biomass and redistributing materials across the landscape. While small mammalian herbivores, such as rodents, are typically inconspicuous, their impacts on plant community structure and chemistry can be large. We used a small mammal exclosure experiment to explore whether rodents in a southeastern old field directly altered the aboveground plant species composition and chemistry, and indirectly altered the belowground soil community composition and activity. In general, when rodents were excluded, C 3 graminoids increased in cover and biomass, contributing toward a shift in plant species composition relative to plots where rodents were present. The plant community chemistry also shifted; plant fiber concentration and carbon : nitrogen were higher, whereas plant nitrogen concentration was lower in exclosure plots relative to access plots. While microbial community enzyme activity increased when rodents were excluded, no significant changes in the fungal : bacterial or potential nitrogen mineralization occurred between treatments. Our results show that rodents can rapidly influence aboveground plant community composition and chemistry, but their influence on belowground processes may require plant inputs to the soil to accumulate over longer periods of time.

No abstract