Rapid prediction of natural durability of larch heartwood using Fourier transform near-infrared spectroscopy

The feasibility of Fourier transform near-infrared (FT-NIR) spectroscopy for rapidly determining the natural durability of the heartwood of larch trees (Larix decidua Mill. and Larix kaempferi (Lamb.) Carriere) was investigated. FT-NIR spectra were collected from solid wood with a fibre-optical probe. Basidiomycetes tests using Coniophora puteana and Poria placenta were carried out on larch heartwood (European standard EN 113), with pine sapwood (Pinus sylvestris L.) used as a reference. The relative resistance to decay (x value) was calculated, and durability classes were estimated according to European standard EN 350-1. Partial least squares regressions between the data sets of wood decay tests (x values) and the FT-NIR spectra were calculated. It was found that multiplicative scatter correction considerably improved the model predictability. High coefficients of correlation (r) and low root mean square errors of prediction (RMSEP) were obtained for cross validation based on wood decay tests with P. placenta (r=0.92, RMSEP=0.077, range 0.27-1.13) and C. puteana (r=0.97, RMSEP=0.078, range 0.07-1.58). Overall, NIR spectroscopy has proven to be an accurate and fast method for the nondestructive determination of natural durability, which might be highly relevant for intensive tree breeding programs and for efforts to optimize wood utilization.