LB 7-64 - Community science reveals macroscale variation in red maple (Acer rubrum) foliar C, N, and N resorption

Background/Question/Methods:

Carbon (C) and nitrogen (N) based traits of green and senesced tree leaves can provide insight into plant-level physiology, plant nutrient status, and ecosystem elemental cycling. Systematic variation in leaf traits within a species throughout its geographic range suggests a shifting nutrient economy in relation to the environment. Measurements of potential intraspecific variability of biogeochemically important leaf traits for many of the most dominant tree species have yet to be examined across the broad climate and latitudinal gradients in which they inhabit. In this study we conducted a community science project that focused on examining macroscale variation Acer rubrum (red maple) foliar C and N concentrations, C:N of green and fallen leaves, and N resorption across broad mean annual temperature (MAT), precipitation (MAP), and latitudinal gradients. We also examined how site specific factors such as habitat and whether the tree was open grown or not influenced foliar traits.

Results/Conclusions:

MAT was negatively correlated with green leaf %N and both fallen leaf C:N and N resorption, but was positively correlated with green leaf C:N and fallen leaf %N. MAP was positively related to fallen leaf %N and negatively with fallen leaf C:N and N resorption. Green leaf %C and %N was significantly higher in open than closed grown sites, but green leaf C:N was significantly higher in closed grown sites. Our results suggest red maple’s leaf physiology and role in biogeochemical processes systematically varies throughout its broad geographic range. Further, our results suggest red maple’s N resorption and recycling through litterfall impacts ecosystem C and N cycles differently throughout its geographic range, such that trees in warmer climates may have a greater reliance on litter derived N on an annual basis relative to trees in cooler climates, which may be more adept at reusing N via resorption.