Climate warming is predicted to alter the structure, stability, and functioning of food webs 1-5 . Yet, despite the importance of soil food webs for energy and nutrient turnover in terrestrial ecosystems, the effects of warming on these food webs - particularly in combination with other global change drivers - are largely unknown. Here, we present results from two complementary field experiments that test the interactive effects of warming with forest canopy disturbance and drought on energy flux in boreal-temperate ecotonal forest soil food webs. The first experiment applied a simultaneous above- and belowground warming treatment (ambient, +1.7 °C, +3.4 °C) to closed-canopy and recently clear-cut forest, simulating common forest disturbance 6 . The second experiment crossed warming with a summer drought treatment (-40% rainfall) in the clear-cut habitats. We show that warming reduces energy flux to microbes, while forest canopy disturbance and drought facilitates warming-induced increases in energy flux to higher trophic levels and exacerbates the reduction in energy flux to microbes, respectively. Contrary to expectations, we find no change in whole-network resilience to perturbations, but significant losses in ecosystem functioning. Warming thus interacts with forest disturbance and drought, shaping the energetic structure of soil food webs and threatening the provisioning of multiple ecosystem functions in boreal-temperate ecotonal forests.
Bibliographical noteFunding Information:
B.S. acknowledges the support of the German Academic Exchange Service (DAAD). A.D.B., M.P.T., U.B., B.R. and N.E. acknowledge the support of the German Centre for integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig funded by the German Research Foundation (FZT 118). A.D.B. was funded by the German Research Foundation within the framework of the Jena Experiment (FOR 1451).
N.E. acknowledges funding by the German Research Foundation (DFG; Ei 862/1, Ei 862/2). This project also received support from the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (grant agreement no 677232 to N.E.). The B4WarmED project has been funded by the US Department of Energy (Grant No. DE-FG02-07ER64456), College of Food, Agricultural and Natural Resource Sciences (CFANS), and Wilderness Research Foundation at the University of Minnesota, and the Minnesota Environment and Natural Resources Trust Fund.
© 2017 The Author(s).