Over the last few decades, scientists have realized that plant species are being lost, gained and redistributed at accelerated rates. It has been suggested that these rapid changes in plant communities could influence the ability of ecosystems to provide life support for consumer communities. However, this suggestion has been controversial because food web properties typically associated with consumer community stability are not usually quantified in plant diveresity experiments designed to test causal mechanisms. We constructed consumer food webs from over 1000 consumer taxa collected in a ten-year grassland biodiversity experiment (The Jena Experiment) and we tested the hypothesis that more diverse plant communities would have more stable network properties.
Results/Conclusions
Our preliminary results show that more diverse plant communities support more consumer species overall, that increases in network size are associated with decreased connectivity that are not paralleled by increases in compartmentalization, and that these effects become stronger through time. These patterns emerge because diverse plant communities were colonized by an increasingly higher proportion of specialist herbivores with low connectance, and by more generalist predators that link consumers associated with each plant. These results demonstrate that mechanisms by which plant diversity stabilizes food webs vary across trophic levels. One implication is that diversity of plants and predators limit the potential for unstable outbreaks of herbivores.