Soil Respiration Responses to Prolonged Warming Vary Seasonally in a Subarctic Grassland

作者：Fabrizzio Protti Sanchez, Linsey Marie Avila, Kathiravan Meeran, Johannes Ingrisch, Páll Sigurðsson, Klaus Steenberg Larsen, Bjarni D. Sigurðsson, Ivan A. Janssens, Michael Bahn · 发表于：Global Change Biology · 年份：2025 · DOI：10.1111/gcb.70388 · 被引用次数：4 · 研究领域：Soil Carbon and Nitrogen Dynamics、Climate change and permafrost、Peatlands and Wetlands Ecology

ABSTRACT Northern ecosystems are warming rapidly, but the effects on soil carbon (C) dynamics are not fully understood. In particular, it is unclear whether warming effects on soil respiration (SR) –the primary source of atmospheric CO 2 from terrestrial ecosystems– persist throughout the year or vary seasonally. While both summer and cold‐season processes shape annual soil C fluxes, the long cold season, which dominates high‐latitude regions, has received far less attention. Using a natural geothermal gradient in a subarctic grassland (+0°C to +10°C above ambient soil temperature), we assessed the effects of more than a decade of continuous soil warming on SR. We obtained high‐resolution year‐round soil CO 2 fluxes and separated geothermal from biological sources of CO 2 following a stable isotope approach. Our findings revealed seasonally variable responses: warming significantly increased SR during the cold season (October–May) but, surprisingly, had no effect during summer (July–September). The lack of a summer warming response likely resulted from warming‐induced soil C depletion and microbial and root adaptations. Overall, prolonged warming altered seasonal C flux dynamics by enhancing the cold‐season contribution to total annual SR. This shift led to a 5.8% rise in annual SR per degree Celsius of warming. Furthermore, the apparent temperature sensitivity of SR (Q 10 ) and the seasonal amplitude of SR declined exponentially with warming intensity, with effects stabilizi...