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Short- and long-term responses of nematode communities to pbkp_redicted rainfall reduction in Mediterranean forests

Abstract:

Climate change is a fundamental process affecting terrestrial ecosystems. However, there is relatively little knowledge about its impacts on soil communities, with a large degree of uncertainty regarding their resistance to pbkp_redicted alterations in temperature and, particularly, precipitation. Moreover, most studies exploring the response of soil biota to pbkp_redicted rainfall reduction have focused on mesic environments and soil microbes, which limit our ability to find general patterns across ecosystems and soil organisms. In this study, we analysed the impact of pbkp_redicted climate change scenarios of rainfall reduction on soil food webs of Mediterranean water-limited forests using nematodes as bioindicators. We took advantage of replicated rainfall exclusion infrastructures (30% exclusion) established in Quercus forests of southern Spain in 2016 (2-year exclusion) and of southern France in 2003 (15-year exclusion) to explore the sensitivity of the soil food web to pbkp_redicted reductions at short- and long-term scales. Rainfall reduction had large negative short-term effects on nematode abundance, particularly of lower trophic groups (bacterivores and fungivores). Rainfall reduction had also consistent short- and long-term impacts on community composition (decrease of fungivores, marginal increase of omnivores) and nematode-based indicators of soil food web structure (higher maturity and structure index, lower prey:predator ratio). These results can be considered indicative of a low resistance of the soil food web to rainfall reductions pbkp_redicted by climate change. Overall, our findings demonstrate the sensitivity of water-limited forests to further reductions in soil water availability, which might substantially alter their soil communities and likely affect the many ecosystem processes that they control.