Non-destructive assessment of Pinus spp. wafers subjected to Gloeophyllum trabeum in soil block decay tests by diffuse reflectance near infrared spectroscopy

The use of calibrated near infrared (NIR) spectroscopy for measuring and predicting the advancement of wood decay in Pinus spp. sapwood wafers that were subjected to Gloeophyllum trabeum for periods ranging from 1 to 10 days was investigated. NIR spectra were obtained from the center of the cross-sectional face of each sample before and after decay tests. Mass loss and compression tests were also used to measure the progression of decay. Calibrations were created from NIR spectra, mass loss, and compression strength data using untreated and mathematically treated (multiplicative scatter correction and first and second derivative) spectra. Strong relationships were derived from the calibrations with the strongest R ² values being 0.98 (mass loss) and 0.97 (compression strength). Calibrations for mass loss showed the strongest statistics for predicting wood decay of a separate test set (0.85 raw, second derivative to 0.76 multiplicative scatter correction (MSC), while predictions for compression strength of the decayed samples resulted in R ² of 0.69 (raw) to 0.54 (MSC). Calibrations created from the amount of time the samples were decayed showed strong statistics, indicating that NIR spectroscopy can predict the early stages of wood decay.