Communities of Collembola show functional resilience in a long-term field experiment simulating climate change

Soil ecosystems, and the fauna they host, are known to provide many services and communities of Collembola can be used as bioindicators of soil functionality. Climate change is often expected to threaten Collembola, however, it is possible that it could also favour them. Previous studies have shown that the structure of collembolan communities can be shaped by long-term adaptation to climate, and that temperature plays a major role in the variation of species traits. In this study, we evaluated how the functional composition and structure of collembolan communities are impacted by climate change using an experimental climate manipulation design. The study used data from the CLIMAITE experiment, which was carried out in Denmark in an unmanaged heath/grassland ecosystem that was subjected to the simulated predicted climate for the year 2075. The climate manipulation experiment parameters included elevated temperature, elevated concentration of atmospheric CO₂ and extended drought, which were tested alone and in combination on a total of 48 plots, including controls. Collembola were sampled using 10-cm-depth soil cores after 1, 2 and 8 years of climate manipulation. We posited (i) that a stimulating factor (elevated CO₂) would increase mean body length, and (ii) that an inhibiting factor (drought) would favour traits indicating a euedaphic life or an ability to present resistance mechanisms (scales, ecomorphosis) and would reduce functional structure indices through environmental filtering. The results did not support these hypotheses. While the findings showed sporadic effects of the climatic treatments on the functional composition and structure, they did not demonstrate any general community response pattern. This may be due to limitations of the study in terms of climatic intensity or community assembly, opening perspectives for future experiments in terms of the choice of traits and measurements.