Reply to Townsend et al.: Decoupling contributions from canopy structure and leaf optics is critical for remote sensing leaf biochemistry (Letter)

Abstract

Townsend et al. (1) agree that we explain the observed relationship (2) between foliar nitrogen (%N) and near-infrared (NIR) canopy reflectance is largely due to structure - i.e., structural variation due to fraction of broadleaf canopy. Our conclusion that the observed correlation with %N is spurious (i.e., lacking a causal basis) is thus clearly justified: we demonstrate that structure explains the great majority of observed correlation, where the structural influence is derived precisely via reconciling the observed correlation with radiative transfer theory.