ABSTRACT Soil respiration (Rs) is a critical component of the carbon cycle in forest ecosystems and is governed by a complex interplay of biotic and abiotic factors. However, the seasonal variations in how Rs respond to these factors remain unclear, particularly in ecologically sensitive karst old‐growth forests. On the basis of these findings, we conducted seasonal measurements of Rs alongside a comprehensive suite of above‐ and belowground variables in a representative subtropical karst evergreen and deciduous broad‐leaved mixed forest and used a structural equation model (SEM) to investigate the dominant drivers of spatiotemporal variation in Rs across different seasons and to elucidate their potential interrelationships. The results indicate that the seasonal variations in Rs are largely determined by soil temperature. Soil temperature ( β —path coefficient in SEM = 0.71), litter organic carbon ( β = 0.06), soil organic carbon ( β = 0.11), soil available phosphorus ( β = −0.08), and slope position ( β = −0.13) directly affect Rs. Additionally, soil temperature variation also constitutes a significant pathway influencing Rs by affecting changes in soil organic carbon and soil available phosphorus contents. Spatially, moderate to strong spatial autocorrelation of Rs was detected across all four seasons. The spatial autocorrelation ranges for spring, summer, autumn, and winter are 15.3, 17.7, 65.3 and 26.4 m, respectively. In spring, soil temperature ( β = 0.35) was the most significant driver of spatial heterogeneity in Rs. During summer, soil factors explained the majority of the spatial heterogeneity in Rs. The autumn Rs was significantly influenced by stand density ( β = −0.20) and slope position ( β = −0.31), whereas the variation in the winter Rs was primarily regulated by litter factors. These findings highlight the critical role of different factors in modulating both the magnitude and spatial heterogeneity of Rs, thereby enhancing our understanding of how forest soil carbon emissions fluctuate with climate change and providing new insights into understand and assess terrestrial ecosystem C cycling.
He et al. (Fri,) studied this question.