Exploring the influence of natural physical variables on wood specific gravity in oak across a broad geographic range

Wood specific gravity (SG) is an essential indicator of wood quality, carbon stock, and the universality of tree functional traits influenced by both genetic and environmental factors. This study investigates the influence of natural physical variables, topography, water availability, and wind exposure on the specific gravity of the Quercus genus across a wide geographic range. Using a Bayesian regression model, we analyzed the relationships between SG and the selected physical variables. Our results indicate that these variables explain a significant proportion of the variation in SG among oak species. Increased topographic complexity leads to higher SG, likely due to stability and resource acquisition challenges in rugged terrain. Water availability is negatively correlated with SG, as higher precipitation or proximity to a river reduces water stress. Wind exposure was also associated with higher SG, likely due to the structural adaptations required to withstand mechanical forces. Our findings align with previous studies on SG variation in other tree species, supporting the hypothesis that environmental stressors drive increases in wood density. These results contribute to a broader understanding of how climate and landscape shape wood properties in the Quercus genus, a keystone component in eastern deciduous forest ecosystems in the United States.