Michigan State University, Michigan, United States
Background/Question/Methods
Trees of many different types show a wide range of variation in bark and wood density, which reflects both internal (genetic) and external forces that shape tree form and function. While wood density has been widely studied by ecologists as key functional trait, much less is known about variation in tree bark density. Here, a large, composite data set, comprised of bark and wood density measurements of thousands of trees of hundreds of species, was analyzed to explore variation in tree bark density, alone, and in combination with wood density, to understand functional diversity of North American tree species.
Results/Conclusions
Analysis of the data indicate a high degree of intra-specific variation in tree bark density that is influenced by both the tree’s growing environment and genetic controls that determine the upper and lower limits of bark density. Within phylogenetic bounds, bark density varies widely relative to wood density, and both can be highly variable, even within different parts of the same tree. The results suggest important functional differences in bark versus wood for physiological adaptation to diverse environmental stresses (e.g., fire, wind, drought) that generate independent and highly plastic responses in the density of bark relative to wood.
