Manipulative experiments and observations along environmental gradients, the two most common approaches to evaluate the impacts of climate change on nutrient cycling, are generally assumed to produce similar results, but this assumption has rarely been tested. We did so by conducting a meta-analysis and found that soil nutrients responded differentially to drivers of climate change depending on the approach considered. Soil carbon, nitrogen, and phosphorus concentrations generally decreased with water addition in manipulative experiments but increased with annual precipitation along environmental gradients. Different patterns were also observed between warming experiments and temperature gradients. Our findings provide evidence of inconsistent results and suggest that manipulative experiments may be better predictors of the causal impacts of short-term (months to years) climate change on soil nutrients but environmental gradients may provide better information for long-term correlations (centuries to millennia) between these nutrients and climatic features. Ecosystem models should consequently incorporate both experimental and observational data to properly assess the impacts of climate change on nutrient cycling.
Bibliographical noteFunding Information:
This work was financially supported by The National Key Research and Development Program of China (2016YFA0600801), the National Natural Science Foundation of China (31370455 and 31570438), and One Hundred Person Project of The Chinese Academy of Sciences (K318021405) and of Shaanxi Province. JP and JS are thankful for the support from European Research Council (ERC) Synergy grant ERC-SyG-2013-610028, IMBALANCE-P, Spanish Government grant CGL2016-79835-P, and Catalan Government grant SGR 2014-274. FTM acknowledges support from the ERC Grant Agreements 242658 (BIOCOM) and 647038 (BIODESERT). M.D-B. acknowledges support from the Marie Sklodowska-Curie Actions of the Horizon 2020 Framework Programme H2020-MSCA-IF-2016 under REA grant agreement No. 702057. The funders had no role in the study design, data collection, data analysis, decision to publish, or preparation of the manuscript
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