Wildfire Reconfigures Soil Function Linkages in a Chinese Boreal Larch Forest

Wildfires alter multiple soil functions in forest ecosystems, but how they reconfigure the linkages between these functions is not fully understood. We evaluated the 1-year-postfire and 11-year-postfire effects of wildfire on carbon sequestration, nutrient cycling, fertility maintenance, and erosion regulation, as well as their relationships, in a Chinese boreal larch forest. We further identified the environmental drivers regulating these associations. One year postfire, the soil fertility index transiently increased by 85%, whereas the carbon sequestration and nutrient cycling declined by 58% and 54%, respectively. Principal component analysis showed that wildfire decoupled the multivariate relationships between four soil functions. While these functions were closely clustered in unburned controls, they became dispersed one year postfire, indicating functional dissociation. After eleven years of recovery, a partial reassembly occurred, but with a reconfigured functional structure distinct from the pre-fire state. For the functional pairs, the impact of wildfire was limited to shifting the relationship between the soil fertility and nutrient cycling from a non-significant negative correlation to a significant positive correlation. Redundancy analysis showed that the soil water content remained the primary environmental driver of soil functional relationships before and after the fire, but its role reversed from negative in unburned stands to positive during the postfire recovery, suggesting a shift toward water-mediated functional coupling. Wildfires in boreal forests have far-reaching effects on soil ecosystems, including impacts on the relationships between various soil functions. Our results indicate that wildfire reconfigures the network of soil function linkages in boreal forests, with implications for the recovery of boreal soil ecosystems.