Estimating Canopy Chlorophyll Concentration from Field and Airborne Spectra

This article investigates the effects of both soil contamination and nitrogen application on the red edge–chlorophyll concentration relationship for a vegetation canopy. Field based canopy reflectance and chlorophyll concentration data were collected at a grassland field site affected by soil contamination and a winter wheat field site affected by different levels of nitrogen fertilisation. The correlation between red edge position (REP) and canopy chlorophyll concentration was r=0.84 and 0.80 for the grassland and winter wheat field sites, respectively. Airborne imaging spectrometry was used to generate REP images (units, nm) of the grassland and winter wheat field sites. Strong correlations were observed between REP and canopy chlorophyll concentration at both field sites. Predictive regression equations were developed to map canopy chlorophyll concentration across the field sites. The rms error of estimated chlorophyll concentration was 0.42 mg g−1 (±12.69% of mean) and 2.09 mg g−1(±16.4% of mean) at the grassland and winter wheat field sites respectively. Results demonstrated the use of remotely sensed estimates of the REP from both field and airborne spectrometers for estimating chlorophyll concentration and indicated the potential of this technique for inferring both land contamination and grain yield.