03566nas a2200421   4500008004100000245014000041210006900181260001400250490000700264520229900271100001702570700001502587700002702602700002402629700002302653700002202676700001702698700002102715700001802736700002402754700001702778700002102795700001602816700001702832700002002849700001902869700001702888700002702905700002102932700002502953700001602978700001802994700002303012700002003035700001303055700001403068856006203082       2017                        eng d00aAsymmetric responses of primary productivity to precipitation extremes: A synthesis of grassland precipitation manipulation experiments0 aAsymmetric responses of primary productivity to precipitation ex  c4376-43850 v233 a<p>Climatic changes are altering Earth&#39;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.</p>1 aWilcox, K.R.1 aShi, Zheng1 aGherardi, Laureano, A.1 aLemoine, Nathan, P.1 aKoerner, Sally, E.1 aHoover, David, L.1 aBork, Edward1 aByrne, Kerry, M.1 aCahill, James1 aCollins, Scott., L.1 aEvans, Sarah1 aGilgen, Anna, K.1 aHolub, Petr1 aJiang, Lifen1 aKnapp, Alan, K.1 aLeCain, Daniel1 aLiang, Junyi1 aGarcia-Palacios, Pablo1 aPeñuelas, Josep1 aPockman, William, T.1 aSmith, M.D.1 aSun, Shanghua1 aWhite, Shannon, R.1 aYahdjian, Laura1 aZhu, Kai1 aLuo, Yiqi  uhttps://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.13706