Plant-Trait Syndromes and Environmental Filtering Drive Biomass Ecology in Resource-Limited Forest Ecosystems.

Understanding the mechanisms driving aboveground biomass (AGB) variation in forest ecosystems is essential for biodiversity conservation and climate-change mitigation, particularly in environmentally heterogeneous and resource-limited regions. Drawing on community assembly theory and trait-based ecology, this study examines how functional dominance and functional diversity interact with soil fertility and climate to regulate AGB across deciduous, evergreen, and mixed forest stands in Pakistan. Using a combination of generalized linear modeling and machine-learning approaches, we found that AGB is primarily structured by functional dominance, with soil fertility exerting an additional but secondary influence. Climatic factors generally constrained biomass accumulation, although their importance varied among forest stand types. Functional diversity played a comparatively minor role. Forest stand type further modulated these relationships, with mixed forests supporting higher biomass and exhibiting the strongest influence of dominant functional traits, while climate effects were more pronounced in evergreen forests and negligible in mixed stands. Overall, our findings indicate that in resource-limited forest ecosystems, biomass accumulation is governed more by the dominance of particular functional strategies and soil resource availability than by functional diversity or climate alone. Integrating plant functional traits and soil conditions into forest management and restoration strategies may therefore enhance biomass productivity and carbon sequestration in heterogeneous landscapes.