Genetic variation of functional traits related to drought tolerance in yellow birch seedlings

Abstract

Understanding patterns of variation in drought-related traits of hardwood trees is crucial for conserving and managing North American temperate forests under climate change. In this study, I examined provenance variation of yellow birch (Betula alleghaniensis Britton) in traits related to drought resistance. Yellow birch is a widespread and economically important eastern North American hardwood species. A common garden approach was used to compare height, diameter, biomass, leaf morphology, and stable carbon isotopes among ten seed sources originating from across Canada and Northern US states. Analysis of variance (ANOVA) of seedling height and diameter did not reveal significant variation in either trait, while ANOVA of a subsample (n=40) revealed significant variation in height and leaf characters (average horizontal width, horizontal width, maximum perpendicular width, perpendicular width 1, and perpendicular width 2). Simple linear regressions revealed significant correlations between variation in leaf morphological traits and climate at seed origin. Temperature-related climate variables were more strongly correlated with leaf traits than precipitation-related climate variables. [...]