Long-term fire legacy effects on leaf and root functional traits and soil nutrients in cold-temperate larch forests of the Greater Khingan Range, China

Aims The Greater Khingan Range is a major cold-temperate forest region in northern China, where climate warming and frequent wildfires have altered ecosystem structure and function. This study examined larch (Larix gmelinii) forests affected by wildfires in 1987 and 2003 to evaluate long-term effects of fire severity on plant functional traits and soil nutrients, and to elucidate post-fire recovery patterns.Method Sites burned in 1987 and 2003 were classified using the Composite Burn Index into unburned, low-, moderate-, and high-severity treatments. Leaf, fine-root, and soil samples (10–20 cm) were collected. Leaf and root morphological, anatomical, and chemical traits, and soil total C, N, P, available N, and pH were measured. Data were analyzed using ANOVA, PCA, PERMANOVA, and Mantel tests.Results Leaf vascular bundle diameter, leaf thickness, and specific leaf area decreased with increasing fire severity. Leaf C decreased under moderate- and high-severity fire, whereas leaf P increased under high severity; leaf N showed no significant differences. Root traits showed stronger multivariate associations with fire severity than leaf traits. Soil total C and N declined with fire severity and were lower in 2003 than in 1987 sites. PERMANOVA indicated that fire severity explained more variation in plant traits, whereas fire year explained more variation in soil traits. Mantel tests showed significant plant–soil nutrient associations.Conclusion After more than three decades, leaf and root traits showed divergent responses: leaf traits retained more persistent individual responses, whereas root traits had stronger multivariate associations with fire severity. Soil nutrients recovered more slowly than vegetation. Post-fire management should prioritize soil recovery in high-severity areas and monitor leaf and root traits sensitive to fire severity.