Scaling Forest Canopy Carbon Flux Measurements From Sites to Landscapes Using Airborne Remote Sensing and Canopy Nitrogen Chemistry

In order to better understand the factors responsible for differences in canopy carbon uptake across a range of sites, we explore how variation in both foliar nitrogen content and climatic conditions relate to maximum rates of gross carbon exchange (GCE) measured at eddy-covariance flux towers. While climate and canopy structural variables alone explain a portion of the observed GCE variation, studies have shown that foliar nitrogen can also act as an important control on carbon uptake and productivity in the eastern forests of the US. We present model results and remote sensing imagery from four sites which span a north-south vegetation and climatic gradient across these forests. High resolution airborne remote sensing techniques, together with ecosystem modeling, are also presented as an intermediate data source and a way of meeting the challenge of scaling from tower based carbon flux measurements to broad scale remote sensing. Airborne hyperspectral remote sensing is used to drive a model of canopy carbon uptake which, in turn, is used to characterize the spatial variability within the 1 km grid size of most global remote sensing products.