Anatomical underpinnings of wood density better associated with growth and mortality of tropical trees
Results/Conclusions: In variation partitioning analysis, juvenile wood density was best predicted by fiber lumen size for cell morphological traits and fiber wall fraction for tissue fractions. Relative growth rates showed moderate associations with fiber wall fraction (R = -0.52), fiber lumen fraction (R = 0.45), and fiber lumen size (R = 0.45). Mortality rates were moderately associated with fiber wall fraction (R = - 0.54), vessel diameter (R = 0.62), and vessel density (R = - 0.46). Prominence of fiber traits, particularly partitioning of fiber area between lumen and wall, confirms a major role for biomechanical demands in driving wood density variation among coexisting species. Nevertheless, wood density was independent of interspecific variation in parenchyma fractions. Anatomical trait variation had consequences for whole-plant function. Associations between relative growth rates and fiber traits demonstrate carbon investment costs of making thicker fiber walls of constant density. Such investment translates to higher survival shown by associations between fiber traits and mortality rates. Safety rather than efficiency of hydraulic transport appears to be of greater priority for survival among coexisting species. Relatively stronger associations between species performance and anatomical traits in our results corroborate the notion that wood density masks variation in ecological strategies.