Large-scale studies reveal strong relationships between climatic conditions and seed predation across central North America

Background/Question/Methods

Large-scale patterns linking energy availability, biological productivity, and diversity form a central focus of ecology and biogeography; understanding how regional climate affects biological processes is also important in an era of global environmental change.  Evidence suggests that the activity and abundance of animals that consume plants may be limited by climatic variables associated with regional biological productivity (e.g. mean annual precipitation and annual evapotranspiration).  However, it remains unclear whether the interactions between plants and consumers are explained by climatic variation across large spatial areas.  At 10 sites across the United States and one site in Canada, we employ a common protocol to provide a large-scale examination of the role of local average climate in affecting seed predation.

Results/Conclusions

We find that annual evapotranspiration is the single best predictor of seed removal; both annual evapotranspiration and mean annual precipitation were positively related to mean seed removal, and both were in three of the top four models.  Annual temperature range (i.e. the difference in minimum and maximum temperatures) was also positively related to seed removal and was included in two of the top four models.  Our work provides the first evidence that energy availability and productivity, which are known to affect consumer abundance and activity, also translate to strong, predictable patterns of seed predation at continental scales.  These findings suggest that future changes in temperature and precipitation could affect plant species persistence in grasslands, through impacts on plant recruitment. More generally, this work illustrates that climatic controls on consumer abundance and activity can indirectly affect interactions across trophic levels. Ongoing work that couples large-scale seed removals with local experimental nutrient addition will provide important insight into the role of local site-level productivity in the interplay between climatic factors and seed removal.