Estimating Canopy Characteristics of Inner Mongolia's Grasslands from Field Spectrometry

This study was designed to estimate the canopy biophysical characteristics of semi-arid grassland ecosystems by using in situ field spectrometry measurements to identify important spectral information for predictions at broader spatial scales. Spectral vegetation indices (VIs), reflectance spectra, continuum removal spectra, and the amplitude of the red edge peak (drre) based on 61 well-replicated field measurements across a large area in Inner Mongolia were used to develop empirical models for estimating four key canopy biophysical features: percent green coverage (PGC), canopy height (H), green aboveground biomass (GBM), and total aboveground biomass (TBM). The results showed that NDVI, EVI, NDSVI, and LSWI were useful for estimating canopy biophysical features, with NDSVI being the most significant variable. The PGC was accurately estimated with spectral reflectance at 441 nm and 2220 nm (R 2 = 0.71), while the maximum depth of band (Dc), absorption area (Darea) in the red domain and drre were selected for estimating TBM and GBM (R 2 = 0.51 and 0.44). Among the four canopy features, PGC received the highest confidence from all of the models (R 2 = 0.81), while H was the most difficult to estimate (R 2 = 0.49). Finally, the degree of disturbances and ecosystem types appeared to be a significant variable for model development. OPEN ACCESS Remote Sens. 2014, 6 2240