Determination of lignin content in Norway spruce foliage using NIR spectroscopy and hyperspectral data
Abstract
The goals of the presented study were: 1) to analyze spectral reflectance curves of Norway Spruce dry foliage samples in order to specify suitable wavelengths for establishing a statistical relationship between the NIR spectra and laboratory determined lignin content; 2) to use this relationship for lignin content prediction in more extended set of Norway spruce needle samples and 3) to apply the derived relation for construction of a lignin content map in Norway Spruce foliage from aerial hyperspectral data in the selected study sites. The resulting lignin content values ranged between 6 % and 32 % of the dry matter depending on the particular area.
Lower average values were discovered in the study sites Erika and Mezihorská. These are the sites with lowest pH values.
Our analysis in accordance with the other studies was not able to determine unambiguously wavelengths that would be really specific for establishing a statistical relationship between the NIR spectra and laboratory determined lignin in foliage generally. The study rather contributed to species-specific determination of lignin in Norway spruce based on the NIR spectra and laboratory determined lignin content leading to construction of a lignin content map in Norway Spruce foliage from HyMap aerial hyperspectral data in the selected study sites.