A novel vegetation index for the detection and age determination of tree resin

In this work, we analysed the reflectance spectrum of spruce trees with the aim of deriving an index based on the NDVI principle that allows easy and fast identification of tree resin on and around spruce trees. The proposed normalized resin difference index uses a wavelength of 1688 nm in combination with either 1093 nm, 1138 nm or 1282 nm to reliably distinguish resin traces from bark and moss. Based on the initial experiments, the proposed index may be promising to be used as an indicator of the age of the resin.