A Multi-Site, Multi-Species Calibration for the Prediction of Cellulose Content in Eucalypt Woodmeal

摘要

Near InfraRed (NIR) spectroscopy can predict cellulose content in ground eucalypt woodmeal, using calibrations developed from the spectra of sets of chemically analysed samples. Most past calibrations have used small sample sets (<100 samples) representing a single stand or region and only one species, making their application to wider populations of samples problematic. A robust, non-destructive prediction capability for eucalypt wood cellulose that works across stands, regions and species would find many applications in tree breeding and resource assessment.Here we describe the development and test the performance of a large (>1000 samples) multi-site and species NIR calibration for predicting cellulose content of eucalypt woodmeal obtained from a range of wood sample types (increment cores, wood chips, stem cross-sections). Most of the samples came from Eucalyptus globulus and E. nitens, although several other species were represented. The calibration was tested against four independent sample sets and explained between 65% and 84% of the variance in each set. A higher proportion of variance was explained in those sample sets that had a wider range of cellulose content. Standard errors of prediction were between 0.5% and 1.5% cellulose for the four independent sample sets. The test samples were added to the large calibration and a new calibration with 1260 samples was developed. Principal components analysis suggests additional wood samples with more diverse chemistries are required to enable the calibration to capture the full variation in cellulose content present in the genus.