Assessment of Above‐Ground Biomass and Soil Organic Carbon Stock Using Taxonomical and Functional Trait Diversity and Management Implications for Land Management in Degrading Temperate Forests of Himalaya

ABSTRACT The present study aims to analyze the relationship between aboveground biomass (AGB) and soil organic carbon (SOC) with plant traits and tree diversity of the 17 forest types of the temperate Himalayas. Leaf and stem traits, along with carbon, were measured across all the forests using 10 random 0.01 ha plots in each forest. The structural equation models for community weighted mean (CWM) and functional divergence (FDvar) were developed separately and jointly for AGB and SOC, each. All three models (CWM, FDvar, and jointly) for both AGB and SOC were significantly impacted by functional diversity metrics of traits and tree diversity, that is, Simpson index. The joint model for biomass had a significant relationship with CWM of diameter at breast height (DBH), tree height, leaf dry matter content, specific leaf area, photosynthetic rate, functional diversity of leaf nitrogen content (LNC), and Simpson index. However, SOC was positively impacted by the CWM of DBH and leaf phosphorus and FDvar of leaf carbon, and negatively by the CWM of LNC. The joint model indicated that dominant trait effects (mass‐ratio) primarily regulate SOC through stem and leaf trait means, whereas specific aspects of functional divergence contributed additional, weaker complementary effects. These patterns suggest that sustaining Himalayan temperate forests under changing environmental conditions requires conserving key species for maintaining functional trait diversity. The model results further imply that enhancing carbon storage can be achieved by promoting functional diversity, managing tree density and spatial structure, and aligning species selection with local environmental conditions.