%0 Journal Article %J Proceedings of the National Academy of Sciences %D 2019 %T Global change effects on plant communities are magnified by time and the number of global change factors imposed %A Kimberly J. Komatsu %A M.L. Avolio %A Lemoine, Nathan P. %A Isbell, Forest %A Grman, Emily %A Houseman, Gregory R. %A Koerner, Sally E. %A Johnson, D.S. %A K.R. Wilcox %A Juha M. Alatalo %A Anderson, J.P. %A Aerts, R. %A S.G. Baer %A Baldwin, Andrew H. %A Bates, J. %A Beierkuhnlein, C. %A Belote, R.T. %A John M. Blair %A Bloor, J.M.G. %A Bohlen, P.J. %A Edward W. Bork %A Elizabeth H. Boughton %A W.D. Bowman %A Britton, Andrea J. %A Cahill, James F. %A Chaneton, Enrique J. %A Chiariello, N.R. %A Cheng, Jimin. %A Scott. L. Collins %A Cornelissen, J.H.C. %A G. Du %A Eskelinen, Anu %A Firn, Jennifer %A Foster, B. %A Gough, L. %A Gross, K. %A Hallett, L.M. %A Han, X. %A Harmens, H. %A Hovenden, M.J. %A Jagerbrand, A. %A Jentsch, A. %A Kern, Christel %A Klanderud, Kari %A Alan K. Knapp %A Kreyling, Juergen %A Li, W. %A Luo, Yiqi %A McCulley, R.L. %A McLaren, Jennie R. %A Megonigal, Patrick %A J.W. Morgan %A Onipchenko, Vladimir %A Pennings, S.C. %A Prevéy, J.S. %A Price, Jodi N. %A P.B. Reich %A Robinson, Clare H. %A Russell, L.F. %A Sala, O.E. %A Seabloom, E.W. %A M.D. Smith %A Soudzilovskaia, Nadejda A. %A Souza, Lara %A K.N. Suding %A Suttle, B.K. %A Svejcar, T. %A Tilman, David %A Tognetti, P. %A Turkington, R. %A White, S. %A Xu, Zhuwen %A Yahdjian, L. %A Yu, Q. %A Zhang, Pengfei %A Zhang, Yunhai %X

Global change drivers (GCDs) are expected to alter community structure and consequently, the services that ecosystems provide. Yet, few experimental investigations have examined effects of GCDs on plant community structure across multiple ecosystem types, and those that do exist present conflicting patterns. In an unprecedented global synthesis of over 100 experiments that manipulated factors linked to GCDs, we show that herbaceous plant community responses depend on experimental manipulation length and number of factors manipulated. We found that plant communities are fairly resistant to experimentally manipulated GCDs in the short term (<10 y). In contrast, long-term (≥10 y) experiments show increasing community divergence of treatments from control conditions. Surprisingly, these community responses occurred with similar frequency across the GCD types manipulated in our database. However, community responses were more common when 3 or more GCDs were simultaneously manipulated, suggesting the emergence of additive or synergistic effects of multiple drivers, particularly over long time periods. In half of the cases, GCD manipulations caused a difference in community composition without a corresponding species richness difference, indicating that species reordering or replacement is an important mechanism of community responses to GCDs and should be given greater consideration when examining consequences of GCDs for the biodiversity–ecosystem function relationship. Human activities are currently driving unparalleled global changes worldwide. Our analyses provide the most comprehensive evidence to date that these human activities may have widespread impacts on plant community composition globally, which will increase in frequency over time and be greater in areas where communities face multiple GCDs simultaneously.

%B Proceedings of the National Academy of Sciences %V 116 %P 17867-17873 %G eng %U https://www.pnas.org/content/early/2019/08/14/1819027116 %N 36 %M KNZ001965 %R 10.1073/pnas.1819027116 %0 Journal Article %J Global Change Biology %D 2017 %T Asymmetric responses of primary productivity to precipitation extremes: A synthesis of grassland precipitation manipulation experiments %A K.R. Wilcox %A Shi, Zheng %A Gherardi, Laureano A. %A Lemoine, Nathan P. %A Koerner, Sally E. %A Hoover, David L. %A Bork, Edward %A Byrne, Kerry M. %A Cahill, James %A Scott. L. Collins %A Evans, Sarah %A Gilgen, Anna K. %A Holub, Petr %A Jiang, Lifen %A Alan K. Knapp %A LeCain, Daniel %A Liang, Junyi %A Garcia-Palacios, Pablo %A Peñuelas, Josep %A Pockman, William T. %A M.D. Smith %A Sun, Shanghua %A White, Shannon R. %A Yahdjian, Laura %A Zhu, Kai %A Luo, Yiqi %X

Climatic changes are altering Earth's hydrological cycle, resulting in altered precipitation amounts, increased interannual variability of precipitation, and more frequent extreme precipitation events. These trends will likely continue into the future, having substantial impacts on net primary productivity (NPP) and associated ecosystem services such as food production and carbon sequestration. Frequently, experimental manipulations of precipitation have linked altered precipitation regimes to changes in NPP. Yet, findings have been diverse and substantial uncertainty still surrounds generalities describing patterns of ecosystem sensitivity to altered precipitation. Additionally, we do not know whether previously observed correlations between NPP and precipitation remain accurate when precipitation changes become extreme. We synthesized results from 83 case studies of experimental precipitation manipulations in grasslands worldwide. We used meta-analytical techniques to search for generalities and asymmetries of aboveground NPP (ANPP) and belowground NPP (BNPP) responses to both the direction and magnitude of precipitation change. Sensitivity (i.e., productivity response standardized by the amount of precipitation change) of BNPP was similar under precipitation additions and reductions, but ANPP was more sensitive to precipitation additions than reductions; this was especially evident in drier ecosystems. Additionally, overall relationships between the magnitude of productivity responses and the magnitude of precipitation change were saturating in form. The saturating form of this relationship was likely driven by ANPP responses to very extreme precipitation increases, although there were limited studies imposing extreme precipitation change, and there was considerable variation among experiments. This highlights the importance of incorporating gradients of manipulations, ranging from extreme drought to extreme precipitation increases into future climate change experiments. Additionally, policy and land management decisions related to global change scenarios should consider how ANPP and BNPP responses may differ, and that ecosystem responses to extreme events might not be predicted from relationships found under moderate environmental changes.

%B Global Change Biology %V 23 %G eng %U https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13706 %N 10 %M KNZ001811 %R 10.1111/gcb.13706 %0 Journal Article %J Ecology Letters %D 2017 %T Asynchrony among local communities stabilises ecosystem function of metacommunities %A K.R. Wilcox %A Tredennick, Andrew T. %A Koerner, Sally E. %A Grman, Emily %A Hallett, Lauren M. %A M.L. Avolio %A Kimberly J. La Pierre %A Houseman, Gregory R. %A Isbell, Forest %A Johnson, David Samuel %A Juha M. Alatalo %A Baldwin, Andrew H. %A Edward W. Bork %A Elizabeth H. Boughton %A W.D. Bowman %A Britton, Andrea J. %A Cahill, James F. %A Scott. L. Collins %A G. Du %A Eskelinen, Anu %A Gough, Laura %A Jentsch, Anke %A Kern, Christel %A Klanderud, Kari %A Alan K. Knapp %A Kreyling, Juergen %A Luo, Yiqi %A McLaren, Jennie R. %A Megonigal, Patrick %A Onipchenko, Vladimir %A Prevéy, Janet %A Price, Jodi N. %A Robinson, Clare H. %A Sala, Osvaldo E. %A M.D. Smith %A Soudzilovskaia, Nadejda A. %A Souza, Lara %A Tilman, David %A White, Shannon R. %A Xu, Zhuwen %A Yahdjian, Laura %A Yu, Qiang %A Zhang, Pengfei %A Zhang, Yunhai %E Gurevitch, Jessica %K Alpha diversity %K alpha variability %K beta diversity %K Biodiversity %K CoRRE data base %K patchiness %K Plant communities %K Primary productivity %K species synchrony %X

Temporal stability of ecosystem functioning increases the predictability and reliability of ecosystem services, and understanding the drivers of stability across spatial scales is important for land management and policy decisions. We used species-level abundance data from 62 plant communities across five continents to assess mechanisms of temporal stability across spatial scales. We assessed how asynchrony (i.e. different units responding dissimilarly through time) of species and local communities stabilised metacommunity ecosystem function. Asynchrony of species increased stability of local communities, and asynchrony among local communities enhanced metacommunity stability by a wide range of magnitudes (1–315%); this range was positively correlated with the size of the metacommunity. Additionally, asynchronous responses among local communities were linked with species’ populations fluctuating asynchronously across space, perhaps stemming from physical and/or competitive differences among local communities. Accordingly, we suggest spatial heterogeneity should be a major focus for maintaining the stability of ecosystem services at larger spatial scales.

%B Ecology Letters %G eng %U http://onlinelibrary.wiley.com/doi/10.1111/ele.12861/epdf %M KNZ001842 %R 10.1111/ele.12861