Locally, plant species richness supports many ecosystem functions. Yet, the mechanisms driving these often-positive biodiversity–ecosystem functioning relationships are not well understood. Spatial resource partitioning across vertical resource gradients is one of the main hypothesized causes for enhanced ecosystem functioning in more biodiverse grasslands. Spatial resource partitioning occurs if species differ in where they acquire resources and can happen both above- and belowground. However, studies investigating spatial resource partitioning in grasslands provide inconsistent evidence. We present the results of a meta-analysis of 21 data sets from experimental species-richness gradients in grasslands. We test the hypothesis that increasing spatial resource partitioning along vertical resource gradients enhances ecosystem functioning in diverse grassland plant communities above- and belowground. To test this hypothesis, we asked three questions. (1) Does species richness enhance biomass production or community resource uptake across sites? (2) Is there evidence of spatial resource partitioning as indicated by resource tracer uptake and biomass allocation above- and belowground? (3) Is evidence of spatial resource partitioning correlated with increased biomass production or community resource uptake? Although plant species richness enhanced community nitrogen and potassium uptake and biomass production above- and belowground, we found that plant communities did not meet our criteria for spatial resource partitioning, though they did invest in significantly more aboveground biomass in higher canopy layers in mixture relative to monoculture. Furthermore, the extent of spatial resource partitioning across studies was not positively correlated with either biomass production or community resource uptake. Our results suggest that spatial resource partitioning across vertical resource gradients alone does not offer a general explanation for enhanced ecosystem functioning in more diverse temperate grasslands.
Bibliographical noteFunding Information:
A. Weigelt, L. Mommer, and J. van Ruijven conceived original idea. A. Weigelt and L. Mommer received funding for this project with input from N. Buchmann, H. de Kroon, N. Eisenhauer, A. Hildebrandt, A. Milcu, C. Roscher, M. Scherer-Lorenzen, and B. Schmid. K. E. Barry collected data sets, analyzed data, wrote initial drafts, and incorporated feedback from all authors. J. van Ruijven, Y. Bai, C. Beierkuhnlein, A. Ebeling, N. Eisenhauer, C. Guimaraes-Steinicke, F. Isbell, A. Milcu, C. Neßhöver, P. Reich, C. Roscher, B. Schmid, L. Sauheitl, D. Tilman, M. Scherer-Lorenzen and S. von Felten provided data and provided detailed feedback on manuscript drafts. The authors would like to thank Alyssa Hallett for the illustrations contained in this manuscript. The Jena Experiment is funded by the German Research Foundation (DFG, FOR 1451) and provided funding for KB. The study conducted in the Montpellier European Ecotron benefited from the CNRS human (Damien Landais, Sebastien Devidal, Clement Piel, and Olivier Ravel) and technical resources allocated to the ECOTRONS Research Infrastructure as well as from the state allocation ‘Investissement d'Avenir’ ANR-11-INBS-0001. The BioCON experiment at Cedar Creek Ecosystem Science Reserve was supported by U.S. National Science Foundation (NSF) Long-Term Ecological Research grants DEB-0620652 and DEB-1234162, Long-Term Research in Environmental Biology grant DEB-1242531, and Ecosystem Sciences grant DEB-1120064 and by U.S. Department of Energy Programs for Ecosystem Research grant DE-FG02-96ER62291. The Big Biodiversity Experiment at Cedar Creek Ecosystem Science Reserve was supported by NSF Long-Term Ecological Research grants DEB-0620652 and DEB-1234162. The BIODEPTH project was funded by the European Commission within the Framework IV Environment and Climate programme (ENV-CT95-0008). B. Schmid was supported by the University of Zurich Research Priority Program on Global Change and Biodiversity (URPP GCB). N. Buchmann was financially supported by the Swiss National Science Foundation (315230E-131194, www.snf.ch). Further financial support came from the German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, funded by DFG (FZT 118).
© 2019 The Authors. Ecology published by Wiley Periodicals, Inc. on behalf of Ecological Society of America
- niche complementarity
- niche partitioning
- resource uptake
- standing root biomass