Grassland management affects soil carbon responses to drought

Drought events are increasingly threatening soil organic carbon (SOC) stability in grasslands, yet the role of grassland management in shaping drought and post-drought responses of SOC remains poorly constrained. We examined how grassland management intensity influences microbial respiration responses during drought and recovery, including the Birch effect (a pulse of soil CO₂ release following rewetting of dry soils) and SOC priming (changes in SOC decomposition triggered by fresh carbon inputs). These responses were assessed in a controlled soil incubation study with experimentally imposed drought, using soils from grasslands covering a range of management types and elevations.

Grassland management strongly altered soil and root properties, including SOC content, fine-root biomass, and bulk density, and caused distinct soil microbial respiration dynamics in response to drought. Respiration was more strongly reduced by drought in soils from intensively managed grasslands, while its recovery from drought was not affected by management intensity. Similarly, the magnitude of the Birch effect following rewetting varied little among management types. In contrast, SOC priming differed strongly among sites and management regimes. Our results suggest that management-induced changes in soil structure and carbon pools modulate SOC responses to drought and subsequent carbon inputs.