Spatial Variation of Post‐Fire Aboveground Carbon Accumulation Rates in Young Forests North of 45°N

Abstract

Forests north of 45°N are vital carbon sinks, but increasing wildfire frequency and intensity threaten their carbon sequestration capacity. This study assesses post‐fire aboveground carbon (AGC) accumulation rates in boreal and temperate forests north of 45°N to better understand carbon recovery patterns. We employed a space‐for‐time substitution approach, integrating remote sensing data and field observations within 1‐degree grid cells, and modeled AGC accumulation over time using the Chapman‐Richards growth function. Our results indicate that during the early recovery period (1–30 years), the mean AGC accumulation rates averaged 0.93 ± 0.53 Mg C ha ⁻¹  yr ⁻¹ , with European forests exhibiting the highest rates at 1.63 ± 0.38 Mg C ha ⁻¹  yr ⁻¹ . Recovery times to reach 85% of old‐growth biomass averaged 87 ± 17 years, varying significantly among regions. Random Forest analysis identified mean annual temperature as a primary driver of AGC accumulation rates, followed by the proportion of mixed forests and summer precipitation. Climate change projections under the SSP1‐2.6 and SSP5‐8.5 scenarios suggest an overall increase in AGC accumulation rates, particularly under the high‐emission pathways. Regional variations are pronounced, with North America predicted to experience significant increases, while Europe may decline due to drought stress. These findings underscore the critical roles of climate and vegetation composition in post‐fire AGC accumulation and highlight the complex interplay of factors influencing forest regrowth. Our spatial estimates provide region‐specific benchmarks for prioritizing post‐fire monitoring and restoration planning in areas with slow or climate‐sensitive carbon recovery and for improving regional carbon accounting.