Climate change will alter precipitation patterns with consequences for soil C cycling. An understanding of how fluctuating soil moisture affects microbial processes is therefore critical to predict responses to future global change. We investigated how long‐term experimental field drought influences microbial tolerance to lower moisture levels (“resistance”) and ability to recover when rewetted after drought (“resilience”), using soils from a heathland which had been subjected to experimental precipitation reduction during the summer for 18 years. We tested whether drought could induce increased resistance, resilience, and changes in the balance between respiration and bacterial growth during perturbation events, by following a two‐tiered approach. We first evaluated the effects of the long‐term summer drought on microbial community functioning to drought and drying–rewetting (D/RW), and second tested the ability to alter resistance and resilience through additional perturbation cycles. A history of summer drought in the field selected for increased resilience but not resistance, suggesting that rewetting after drought, rather than low moisture levels during drought, was the selective pressure shaping the microbial community functions. Laboratory D/RW cycles also selected for communities with a higher resilience rather than increased resistance. The ratio of respiration to bacterial growth during D/RW perturbation was lower for the field drought‐exposed communities and decreased for both field treatments during the D/RW cycles. This suggests that cycles of D/RW also structure microbial communities to respond quickly and efficiently to rewetting after drought. Our findings imply that microbial communities can adapt to changing climatic conditions and that this might slow the rate of soil C loss predicted to be induced by future cyclic drought.

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Climate change is associated with an increased risk in the occurrence of wildfires. Forests store large amounts of carbon (C), which are threatened by these wildfires. Pyrogenic material produced after a wildfire constitutes an important part of the soil organic carbon pool in forest soils. Microorganisms play an important role in the cycling of C. This study investigated microbial activity in dissolved char from burned wood from two tree species in different stages of decay. The char from branches of beech and Norway spruce was produced under laboratory fire conditions and extracted in water after which microbial activity was measured for a 4-week period. Further stages of decay resulted in increased flammability with higher peak temperatures and combustion completeness. For the beech samples, further decay also resulted in a decrease of extractable C but a higher proportion of stable C. Further decay resulted in less respiration for beech and more for Norway spruce. With less C being respired, this points towards an increased C sequestration potential in the form of microbial C and microbial derived products for beech compared to Norway spruce. This study provided a workflow to assess the effects of dissolved char on microbial activity by mimicking natural fire conditions. It also indicated the need for future research to further elucidate the underlying mechanisms explaining why fire-originated dissolved char of wood in different decay stages influences microbial respiration with diverging effects per species.