Measurement of cellulose content, Kraft pulp yield and basic density in eucalypt woodmeal using multisite and multispecies near infra-red spectroscopic calibrations

  • GM Downes
  • R Meder
  • H Bond
  • N Ebdon
  • C Hicks
  • C Harwood

Abstract

Previous descriptions of multisite and multispecies near infra-red (NIR) spectroscopic calibrations for predicting cellulose content (CC) and Kraft pulp yield (KPY) in eucalypt woodmeal demonstrated that large, single calibrations provide precise predictions for a wide range of sites and species. These have since been used in a range of published studies. Their value lies in low-cost, fast analytical throughput and small required sample size. In particular, they allow precise values of KPY to be obtained from small wood samples obtained non-destructively. This study reports the ongoing performance of these calibrations with respect to laboratory chemical values, as well as describing a wood density calibration. Cellulose content was measured in an additional 550 samples taken from over 14 different data sets. The standard error of prediction (SEP) of CC was 0.35% with an average bias of only 0.28%. Adding these samples to the existing calibration gave a sample set of 1 800 samples, producing a calibration with a crossvalidation r2 of 0.87 and standard error of 0.78%. The existing KPY calibration was assessed against an additional 527 samples generating a standard error of prediction of 1.9%and a bias of -1.8%. Adding the samples to the calibration gave a sample set of 1 360 samples producing a calibration with a crossvalidation r2 of 0.87 and standard error of 1.29%. The correlation between NIR-predicted CC and NIR predicted KPY was 85%. A wood density calibration was developed using data generated from wood chips. A total of 1 138 samples were separated randomly into calibration and test sets, representing between 19% and 38% of the sample set. The SEP values were between 34 and 40 kg m-3 and explained between 72% and 84% of the variance. The final calibration including all samples had a crossvalidation r2 of 0.82 and standard error of 29.5 kg m-3.

Keywords: cellulose, eucalypt, Kraft pulp yield, near infra-red spectroscopy, wood density, woodmeal

Southern Forests 2011, 73(3&4): 181–186

Author Biographies

GM Downes
CRC for Forestry, Private Bag 12, Hobart, TAS 7001, Australia; CSIRO Sustainable Ecosystems, Private Bag 12, Hobart, TAS 7001, Australia
R Meder
CRC for Forestry, Private Bag 12, Hobart, TAS 7001, Australia; CSIRO Plant Industry, 306 Carmody Road, St Lucia, QLD 4067, Australia
H Bond
CRC for Forestry, Private Bag 12, Hobart, TAS 7001, Australia;  School of Plant Science, University of Tasmania, Private Bag 55, Hobart, TAS 7001, Australia
N Ebdon
CRC for Forestry, Private Bag 12, Hobart, TAS 7001, Australia; CSIRO Materials Science and Engineering, Private Bag 10, Clayton, VIC 3168, Australia
C Hicks
CRC for Forestry, Private Bag 12, Hobart, TAS 7001, Australia; HRL Technology Pty Ltd, Level 1, Unit 9, 677 Springvale Road, Mulgrave, VIC 3170, Australia
C Harwood
CRC for Forestry, Private Bag 12, Hobart, TAS 7001, Australia; CSIRO Sustainable Ecosystems, Private Bag 12, Hobart, TAS 7001, Australia
Section
Articles

Journal Identifiers


eISSN: 2070-2639
print ISSN: 2070-2620