Rapid Assessment of Southern Pine Decayed by G. Trabeum by near Infrared Spectra Collected from the Radial Surface

The use of near infrared (NIR) spectroscopy for predicting levels of degradation in southern pine (Pinus spp.) by Gloeophyllum trabeum for periods over 1-8 da was investigated. NIR spectra collected from the center of the radial face of each sample after laboratory soil block decay tests were used to develop calibrations. Calibrations were developed for mass loss, compression strength, and exposure period using data measured from prior methods and untreated and mathematically treated (multiplicative scatter correction and first and second derivative) NIR spectra from various ranges of wavelengths by partial least squares regression. Strong relationships were derived from the calibrations with the strongest R values of 0.97 (exposure period), 0.94 (compression strength), and 0.91 (mass loss). Calibrations for exposure period showed the strongest statistics for predicting wood decay of the validation test set (R 1⁄4 0.92; RPDp [ratio of the standard deviation of the measured data to the standard error of prediction] 1⁄4 3.95 [first derivative, 1100-2250 nm]), while predictions for mass loss of the decayed samples resulted in R 1⁄4 0.86 and an RPDp 1⁄4 3.17 (multiplicative scatter correction, 1100-2500 nm), and the strongest compression strength prediction resulted in R 1⁄4 0.76 and an RPDp 1⁄4 2.50 (second derivative, 1100-2500 nm). These results suggest that NIR spectroscopy can adequately predict wood decay from spectra collected from the radial face of southern pine.