Plant diversity effects on grassland productivity are robust to both nutrient enrichment and drought

Authors: CRAVEN, DYLAN - Leipzig University; ISBELL, FOREST - Leipzig University; MANNING, PETE - University Of Bern; BRUELHEIDE, HELGE - University Of Bern; EBELING, ANNE - University Of Jena; ROSCHER, CHRISTIANE - Helmholtz Centre; VAN RUIJVEN, JASPER - Wageningen University; WEIGELT, ALEXANDRA - Leipzig University; WILSEY, BRIAN - Iowa State University; BEIERKUHNLEIN, CARL - University Of Bayreuth; CONNOLLY, JOHN - University College Dublin; DE LUCA, ENRICA - University Of Zurich; GRIFFIN, JOHN - Swansea University; HAUTIER, YANN - Utrecht University; HECTOR, ANDY - University Of Oxford; JENTSCH, ANKE - University Of Bayreuth; KREYLING, JURGEN - Ernst Moritz Arndt University Of Greifswald; LANTA, VOJTECH - University Of South Bohemia; LOREAU, MICHEL - Centre National De La Recherche Scientifique; MEYER, SEBASTIAN - Technische Universitat Munchen; MORI, AKIRA - Yokohama National University; NAEEM, SHAHID - Columbia University; PALMBORG, CECILIA - Swedish University Of Agricultural Sciences; Polley, Herbert; REICH, PETER - University Of Minnesota; SCHMID, BERNHARD - University Of Zurich; SIEBENKAS, ALRUN - Helmholtz Centre For Environmental Research; SEABLOOM, ERIC - University Of Minnesota; THAKUR, MADHAV - Leipzig University; TILMAN, DAVID - University Of Minnesota; VOGEL, ANJA - University Of Jena; EISENHAUER, NICO - Leipzig University

Submitted to: Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/8/2016
Publication Date: 4/25/2016
Publication URL: http://handle.nal.usda.gov/10113/62560
Citation: Craven, D., Isbell, F., Manning, P., Bruelheide, H., Ebeling, A., Roscher, C., Van Ruijven, J., Weigelt, A., Wilsey, B., Beierkuhnlein, C., Connolly, J., De Luca, E., Griffin, J., Hautier, Y., Hector, A., Jentsch, A., Kreyling, J., Lanta, V., Loreau, M., Meyer, S.T., Mori, A.S., Naeem, S., Palmborg, C., Polley, H.W., Reich, P.B., Schmid, B., Siebenkas, A., Seabloom, E., Thakur, M.P., Tilman, D., Vogel, A., Eisenhauer, N. 2016. Plant diversity effects on grassland productivity are robust to both nutrient enrichment and drought. Philosophical Transactions of the Royal Society of London. Series B, Biological Sciences. 371:20150277. doi:10.1098/rstb.2015.0277.

Interpretive Summary: Humans are adding trace gases to the atmosphere. Potential consequences include a shift in the timing or amount of precipitation and increased deposition of nitrogen on land surfaces. Both of these changes will alter plant productivity. But, the amount by which precipitation change and nitrogen input will alter productivity of natural and semi-natural vegetation, such as grasslands, likely will depend on the number and types of plant species that are growing in a given area. We used data from 16 grassland experiments across North American and Europe to determine whether the response of plant productivity to nitrogen fertilization and rainfall exclusion depended on the number of plant species present. Vegetation growth was greater when many rather than few species were present regardless of whether nitrogen was added or withheld and regardless of whether or not precipitation was excluded. On the other hand, diversity buffered plant response to both types of resource alteration, such that proportional changes in productivity were smaller in diverse than depauperate communities. Our results indicate that maintaining or increasing the number of plant species in grasslands may be an effective tool for reducing year-to-year variability in the provision of forages and feedstocks.

Technical Abstract: Global change drivers are rapidly altering resource availability and reducing biodiversity. Here, we evaluate the extent to which biodiversity influences the response of ecosystem productivity to increases or decreases in resource availability across grassland experiments. This was done using data from 16 grassland experiments across North America and Europe that manipulated both plant species richness and an essential resource: soil nutrients or water. We assessed the interaction between plant diversity and resource alteration as both positive interactions with diversity, e.g. more complete utilization of additional nutrients at high plant diversity, and negative interactions, e.g. the breakdown of complementarity for limiting resources, could be expected. Despite strong increases in productivity with nutrient addition and decreases in productivity due to water reduction, we found that resource alterations did not alter the strength of diversity effects on productivity. Standardizing for absolute productivity changes revealed a consistent yet weak and non-significant trend for diversity to buffer the effects of both drought and nutrient enrichment. The immutability of diversity effects indicates that diversity will remain an important regulator of grassland ecosystem productivity, regardless of changes in other global change drivers.