2005: Potential of Spectral Feature Analysis to Estimate Nitrogen Concentration

Leaf nitrogen content is of great interest because of its role in photosynthesis, ecosys-tem productivity and thus influences global cycling of carbon and oxygen. The nitrogen concentration of a mixed forest in Switzerland was explored using HyMap data. The imaging spectrometer data were processed to correct for atmospheric and geometric distortion. In this preliminary study the spectral data was investigated using continuum removal analysis. In order to reduce external influences a normalization procedure was used. Relationships between transformed reflectance and field-measured nitrogen concentration were investigated by using correlograms. A backward stepwise linear regression routine was applied to select the most important bands in predicting the response variable. This preliminary study showed that continuum removal analysis is applicable on HyMap data in complex mixed forests. Differences among plant functional types as well as species are visible in the normalized band depths curves. Correlations between transformed HyMap spectral data and measured nitrogen concentration could be found.