This document summarizes research on the response of sugar maple leaf traits to nitrogen, phosphorus, and vertical gradients within the tree canopy. The study found that specific leaf area, nitrogen concentration, and chlorophyll concentration were higher in leaves from the upper canopy and in trees treated with additional nitrogen and nitrogen+phosphorus. Principal component analysis identified chlorophyll A and soluble ions as important drivers of the nutrient treatment responses. The results indicate that not accounting for vertical variation in leaf traits like nitrogen can lead to overestimates of carbon assimilation.