Wind speed and relative humidity influence spatial patterns of burn severity in boreal forests of northeastern China

Abstract

Key message: We investigated relationships between the spatial patterns of burn severity in Chinese boreal forests and weather parameters. Patch size, shape and arrangement differed between high-severity and low/moderate-severity patches. Wind speed and relative humidity were dominant weather parameters of spatial variation in burn severity. Patch size negatively correlated with relative humidity; patch complexity and aggregation positively correlated with wind speed. Context: Spatial patterns of burn severity strongly control post-fire succession and numerous ecological processes in fire-prone boreal forests. Burn-severity patterns are strongly tied to weather conditions. Understanding how weather influences spatial patterns of burn severity is critical for predicting burn severity and fire management strategies. Aims: We investigated relationships between spatial patterns of burn severity and weather variables in the Chinese boreal forests. Methods: Using satellite imagery, we mapped burn severity for 22 fires that occurred between 2000 and 2005. For each fire, we calculated metrics of spatial pattern. Using Random Forest models, we quantified the relative importance of weather variables in determining spatial patterns of burn severity. Results: High-severity fire patch, averaged 570.5 ha (SD = 1530.6), was the dominant outcome, occupying 67.8% of all area burned across the 22 fires. High-severity patches were larger, more aggregated, and simpler in shape than low- and moderate-severity patches. Patch size of high-severity fires increased in drier and less humid conditions, and patches were more complex and aggregated with higher wind speeds. Conclusion: With drier conditions predicted with climate change, spatial patterns of burn severity in Chinese boreal forests may become increasingly homogeneous, possibly affecting long term ecological functions.