Theory predicts that consumers may stabilise or destabilise plant production depending on model assumptions, and tests in aquatic food webs suggest that trophic interactions are stabilising. We quantified the effects of trophic interactions on temporal variability (standard deviation) and temporal stability (mean/standard deviation) of grassland biomass production and the plant diversity–stability relationship by experimentally removing heterotrophs (large vertebrates, arthropods, foliar and soil fungi) from naturally and experimentally assembled grasslands of varying diversity. In both grassland types, trophic interactions proportionately decreased plant community biomass mean and variability over the course of 6 years, leading to no net change in temporal stability or the plant diversity–stability relationship. Heterotrophs also mediated plant coexistence; their removal reduced diversity in naturally assembled grasslands. Thus, herbivores and fungi reduce biomass production, concurrently reducing the temporal variability of energy and material fluxes. Because of this coupling, grassland stability is robust to large food web perturbations.
Bibliographical noteFunding Information:
We would like to thank H. Muller-Landau, R. Montgomery and D. Tilman for contributions to designing and implementing the heterotroph manipulation experiments. We are grateful to J. Anderson, D. Bahauddin, A Krause, T. Mielke and many Cedar Creek LTER summer interns for help with logistics, data collection and curation. This manuscript has benefited immensely from comments provided by three anonymous reviewers, Sarah Hobbie, Forest Isbell, Laura Dee, Aamod Zambre and members of the Borer-Seabloom laboratory group. This work was supported by grants from the US National Science Foundation Long-Term Ecological Research Program (LTER) including DEB-0620652 and DEB-1234162 and by the Cedar Creek Ecosystem Science Reserve and the University of Minnesota.
© 2019 John Wiley & Sons Ltd/CNRS
- Biodiversity loss
- consumer effects
- ecosystem functioning
- ecosystem stability
- plant–herbivore interaction
- plant–pathogen interaction