Variations of the NIR spectra in relation to the growing conditions of Spruce (Picea abies L. Karst.) trees in northern Italy

Many wood properties are related with the site characteristics, since the tree records all the environmental factors into the wood. Even though, it has always been considered a difficult task to identify the origin of a timber, no effective tools are presently available for this purpose. The goal of this work is to check if significant differences occur among the sets of wood properties of spruce (Picea abies L. Karst.) timber provenances harvested in various locations of Trentino region in northern Italy, by using Fourier transform near infra-red spectroscopy (FT-NIR). Wooden samples were collected from neighboring forests\districts but differencing in terms of the altitude, soil structure or silvicultural history. Measured spectra were preprocessed and analyzed by using PCA and cluster analysis. It was found that the separation among groups related to the attitude and exposition was possible. It was concluded that trees growing in various locations have some differences in the chemical composition and FT-NIR is sensitive enough to detect such differences. The method here presented could be used, in wide areas, for tracking wood provenances and as a technical tool for detecting the logs coming from protected areas (illegal logging detection).