Seasonal Inconsistency: The Uneven Effect of Disturbances and Permafrost on Biogeochemical Processes in Larix gmelinii Forests of Eastern Eurasia

ABSTRACT Boreal larch forests remain vulnerable to disturbances that threaten their function as carbon sinks. We investigated the seasonal dynamics of soil respiration ( R s ), litter respiration ( R L ), and enzyme activity in post‐fire, clear‐cut, and undisturbed larch forests in the discontinuous permafrost zone of Eastern Eurasia, 16 years after disturbance. We found that the effects of disturbances on R s might persist for decades. During its seasonal peak in July, R s was 1.5 to 2 times higher in disturbed than in undisturbed forests. In contrast to R s , disturbances did not affect heterotrophic R L . Differences in enzyme activity in forest litter between post‐fire and clear‐cut sites, compared to undisturbed sites, were only observed in spring and autumn. The increase in R s , but not in R L , indicates a greater influence of fire and clear‐cutting on autotrophic and heterotrophic respiration in the mineral soil compared to microbial activity in the litter. In the forests on the permafrost, we observed altered biological parameters, including a summer increase in R s , R L , and seasonal changes in the litter enzyme activity. Overall, the seasonal patterns of R L and enzyme activity are mediated by different ecological factors across the study sites. Temperature and pH are significant factors in undisturbed stands, while dissolved organic carbon becomes more prominent in disturbed sites. These insights are crucial for predicting carbon dynamics and the resilience of boreal ecosystems amid rising climate change and increasing disturbance frequency. Future research should integrate spatial and temporal scales to assess the long‐term effects of disturbances in boreal forests.