Remote sensing of canopy chemistry and nitrogen cycling in temperate forest ecosystems

Abstract

Foliar lignin content (referring to acid-insoluble fibre in foliage) is a primary rate-limiting factor of forest-litter decomposition and is thus important in modulating nutrient-cycling rates in forest ecosystems. Here we report the use of images acquired by the Airborne Imaging Spectrometer, an experimental high-spectral-resolution imaging sensor developed by NASA, to estimate the lignin concentration of whole forest canopies in Wisconsin. The observed strong relationship between canopy lignin concentration and nitrogen availability (through nitrogen mineralization) in seven undisturbed forest ecosystems on Blackhawk Island, Wisconsin, suggests that canopy lignin may serve as an index for site nitrogen status. This predictive relationship presents the opportunity to estimate nitrogen-cycling rates across forested landscapes through remote sensing.