Replication data for: Limitations to use of infrared spectroscopy for rapid determination of carbon-nitrogen and wood density for tropical species

Abstract

Infrared (IR) spectroscopy was used as a rapid and non-destructive method to determine, carbon (C), nitrogen (N) and tree wood density.A total of 82 sample cores were scanned in the reflectance mode from 4000 to 400 cm-1 for mid-infrared (MIR) spectra and from 8000 to 4000cm-1 and 11000-4000cm-1 for near infrared (NIR) spectra. The reference values for C and N were measured using combustion method while wood density was calculated using auger method. Calibrat ion equations were developed using partial least-squares and first derivative spectra. Root mean square error (RMSEP) was used to calculate prediction error. Predict ion of Cusing MIR spectra gave R2 = 0.59, RMSEP = 0.02; NIR spectra R2 = 0.50, RMSEP = 0.02, whileN prediction usingMIR spectra had R2 = 0.54, RMSEP = 0.22; NIR spectra R2 = 0.48, RMSEP =0.24. Wood density prediction was fair for MIR (R2= 0.7
9, RMSEP = 0.14); NIR (R2= 0.69, RMSEP = 0.17).Improved predictions using NIR were for extendedspectral range;though accuracies were inferior to MIR. Both MIR and NIR models showed good potentials to be used as rapid and cost effective method of predict ing C-N andwood density.
Keywords Infrared Spectroscopy, Partial Least Squares Regression,Carbon, Nitrogen,Wood Density