Disentangling Habitat-specific Pathways of Forest Biomass Loss: A Structural Equation Modeling Approach Across Temperate and Subtropical Forests

Abstract

This study examined how elevation, habitat diversity, and soil nitrogen interact to influence forest biomass across ecological zones. A field survey was conducted using 300 plots, systematically allocated across three habitat types with equal representation. The relationships were measured using bivariate analysis, correlation study, and structural equation modeling (SEM). The habitat-unified model revealed that elevation had a statistically significant direct effect on biomass (β = 0.71, p < 0.001), as well as indirect effects through species richness (β = 0.37, p < 0.001) and soil nitrogen (β = 0.15, p < 0.05). Moist forest habitats were shown to increase soil nitrogen content  (β = 0.37, p < 0.001) and species richness (β = 0.28, p < 0.001) significantly. Habitat-specific models revealed that the strength and direction of these relationships varied between forest types. Degradation had a strong negative effect on biomass in subtropical ecosystems (β = 0.34, p < 0.0001) and in moist temperate forests (β = 0.61, p < 0.0001). Degradation reduced biomass in subtropical and moist temperate forests but had no significant effect in dry temperate forests. However, it strongly decreased soil nitrogen and, together with elevation, constrained biomass.