Wiley, Global Change Biology, 12(19), p. 3872-3884, 2013
DOI: 10.1111/gcb.12338
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We investigated how the legacy of warming and summer-drought affected microbial communities in five different replicated long-term (>10 years) field-experiments across Europe (EU-FP7 INCREASE infrastructure). To focus explicitly on legacy effects (i.e. indirect rather than direct effects of the environmental factors), we measured microbial variables under the same moisture and temperature in a brief screening, and following a pre-incubation at stable conditions. Specifically, we investigated the size and composition of the soil microbial community (PLFA) alongside measurements of bacterial (leucine incorporation) and fungal (acetate in ergosterol incorporation) growth rates, previously shown to be highly responsive to changes in environmental factors, and microbial respiration. We found no legacy effects on the microbial community size, composition, growth rates or basal respiration rates at the effect sizes used in our experimental setup (0.6°C, about 30% precipitation reduction). Our findings support previous reports from single short-term ecosystem studies thereby providing a clear evidence base to allow long term, broad scale generalizations to be made. The implication of our study is that warming and summer drought will not result in legacy effects on the microbial community and their processes within the effect sizes here studied. While legacy effects on microbial processes during perturbation cycles, such as drying-rewetting, and on tolerance to drought and warming remains to be studied, our results suggest that any effects on overall ecosystem processes will be rather limited. Thus, the legacies of warming and drought should not be prioritised factors to consider when modelling contemporary rates of biogeochemical processes in soil. This article is protected by copyright. All rights reserved.