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FT-NIR spectroscopy in predicting the decay resistance related characteristics of solid Scots pine (Pinus sylvestris L.) heartwood

Abstract FT-NIR spectroscopy equipped with a fiber optic probe was used to predict the mass loss caused by a brown-rot fungus (Coniophora puteana) in Scots pine heartwood. Because decay tests are impractical for generating reference data for the calibration of prediction models, the possibilities of using the concentration of heartwood extractives as a reference variable instead of mass loss was studied. The material investigated covered a wide range of natural variation in durability and diffuse reflectance infrared Fourier transform spectra were recorded from the cross section of 41 pines. The partial least square (PLS) regression models were found to be satisfactory for prediction of the mass loss and the concentration of extractives (total phenolics, resin acids, pinosylvin and pinosylvin monomethyl ether). It was concluded that FT-NIR spectroscopy has the potential to become a tool for the decay resistance grading of Scots pine heartwood timber, especially if the prediction models will be based on heartwood extractives.