Fire-regime variability impacts forest carbon dynamics for centuries to millennia

Wildfire is a dominant disturbance agent in forest ecosystems, shaping important biogeochemical processes including net carbon (C) balance. Long-term monitoring and chronosequence studies highlight a resilience of biogeochemical properties to large, stand-replacing, high-severity fire events. In contrast, the consequences of repeated fires or temporal variability in a fire regime (e.g., the characteristic timing or severity of fire) are largely unknown, yet theory suggests that such variability could strongly influence forest C trajectories (i.e., future states or directions) for millennia. Here we combine a 4500-year paleoecological record of fire activity with ecosystem modeling to investigate how fire-regime variability impacts soil C and net ecosystem carbon balance. We found that C trajectories in a paleo-informed scenario differed significantly from an equilibrium scenario (with a constant fire return interval), largely due to variability in the timing and severity of past fires. ...

野火是森林生态系统中的主导干扰因子，塑造着包括净碳（C）平衡在内的重要生物地球化学过程。长期监测与时间序列研究表明，生物地球化学特性对大规模、林分更替型、高烈度火灾事件具有恢复力。相比之下，重复火灾或火格局（如火灾的特征发生时间或烈度）的时间变异性所带来的后果在很大程度上仍未知，但理论指出，此类变异性可能在数千年内强烈影响森林碳轨迹（即未来状态或方向）。本研究结合4500年的古生态火灾活动记录与生态系统建模，探究火格局变异性如何影响土壤碳及生态系统净碳平衡。研究发现，基于古生态信息的情景下的碳轨迹与平衡情景（具有恒定的火灾返回间隔）存在显著差异，这主要归因于历史火灾在发生时间和烈度上的变异性。...