Near infrared spectroscopy: A rapid nondestructive method for - PowerPoint PPT Presentation

Near infrared spectroscopy: A rapid nondestructive method for measuring wood properties and its application to tree breeding L. R. Schimleck Warnell School of Forestry and Natural Resources The University of Georgia

Overview • Introduction to NIR spectroscopy • Rapid estimation of pulp yield by NIR spectroscopy • Multiple-species, multiple-site calibrations • Application of calibrations to new sites • Estimating whole-tree properties using core spectra • Estimation of the wood properties of radial strips • Field based NIR spectroscopy • Estimation of genetic parameters using NIR data • Conclusions — 2 —

Introduction to NIR spectroscopy • NIR spectrum just above visible region of the electromagnetic spectrum (EMS) 800 to 2500 nm • Overtones, combinations of fundamental IR vibrations (stretch, bend) Increasing Frequency 50,000 cm -1 12,500 cm -1 4,000 cm -1 400 cm -1 FIR, X-Ray UV Visible IR Microwave NIR 200nm 380nm 800nm 2500nm 25,000nm Increasing Wavelength • Frequency = 1 / wavelength — 3 —

Introduction to NIR spectroscopy 0.6 C-H vibr ation thr oughout spectr um 0.5 O-H N-H Log (1/Reflectance) N-H 0.4 O-H 0.3 N-H S-H 0.2 0.1 0 1100 1300 1500 1700 1900 2100 2300 2500 Wavelength (nm) — 4 —

Introduction to NIR spectroscopy Estimation of a parameter involves the following steps: • Collect spectra of calibration samples • Develop a calibration (regression) (y = B0 + X1*B1 + X2*B2 + ………..+ XN*BN) • Collect NIR spectra of test (or unknown) samples • Estimate parameter of interest for test set samples using the calibration — 5 —

Rapid estimation of pulp yield by NIR • Earliest work reported in the late 1980’s • Wood chemistry (pulp yield, cellulose and lignin) • Pulp yield particularly important and a rapid method for its estimation had long been sought • Some good results obtained, but calibrations tested on samples drawn from the same population • Calibration / prediction statistics variable – accuracy of data and its range both important — 6 —

Rapid estimation of pulp yield by NIR Many practical questions raised: • Are multi-site, multi-species calibrations possible? • Can a calibration from one site be used to accurately estimate the wood properties of samples from a different site? • Can whole-tree wood properties be estimated using NIR spectra from cores? — 7 —

Multiple-species, multiple-site calibrations Common in agriculture, 20,000+ samples, multiple countries represented • Yet to be achieved for wood – NIR research Potential reasons: • NIR applied to wood for only a short time • Difficulty and cost of measuring pulp yield • Pulping methods differ between laboratories — 8 —

Multiple-species, multiple-site calibrations • Garbutt et al. (1992) - 13 eucalypt species, 1 hybrid • Michell (1995) - Tasmanian E. globulus , 10 locations • Michell & Schimleck (1998) – Tasmanian E. globulus and E. nitens , multiple sites • Schimleck et al. (2006) - 7 eucalypt species, 5 hybrids from 3 locations in Brazil • Hodge & Woodbridge (2004) – 5 pine species • Ensis – 700+ samples, multiple eucalypt species — 9 —

Multiple-site E. nitens calibration 56 54 Measured pulp yield (%) 52 50 48 8 factors R 2 = 0.91 SEC = 0.64 46 SECV = 0.78 RPD c = 2.79 44 44 46 48 50 52 54 56 NIR-estimated pulp yield (%) Source: SCHIMLECK, L.R.; KUBE, P.D.; RAYMOND, C.A.; MICHELL, A.J.; FRENCH, J. 2006: Extending near infrared reflectance (NIR) pulp yield calibrations to new sites and species. J. Wood Chem. Technol. 26 : 299-311. — 10 —

Multi eucalypt species, multiple-site calibration 65 60 Measured pulp yield (%) 55 50 45 40 R 2 = 0.90 35 35 40 45 50 55 60 65 NIR-predicted pulp yield (%) Source: G. Downes, Ensis — 11 —

GLOBAL versus LOCAL calibrations GLOBAL approach – build large data set, hope to include all sources of variation LOCAL approach – build a specific equation to predict a given property for a new sample • The new calibration is obtained using samples selected from a large database on the basis of their similarity to the unknown • Several studies have demonstrated that LOCAL calibrations provide smaller predictive errors than GLOBAL calibrations • Provides the benefits of using a GLOBAL strategy (large database encompassing the variation), with the accuracy of specific calibrations • Establishment of a large database (1000’s of samples) is critical — 12 —

Application of calibrations to new sites A true test of a calibration…….. • Performance of the calibration may suffer owing to multiple differences between sites • Presently no way of testing if a calibration will accurately predict wood properties or not • Findings indicate that relationship between lab measured data and NIR predicted data will be good • Addition of a small number of samples from the new location will reduce predictive errors — 13 —

PPY for Southern Tas using Northern Tas calibration 56 R 2 = 0.87 54 NIR predicted pulp yield (%) 52 50 48 9 of the top 12 46 45 47 49 51 53 55 Laboratory determined pulp yield (%) Source: SCHIMLECK, L.R; RAYMOND, C.A.; BEADLE, C.L.; DOWNES, G.M. KUBE, P.D.; FRENCH, J. 2000: Applications of NIR spectroscopy to forest research. Appita J. 53: 458-464 . — 14 —

PPY for Gog (Tasmania) using Northern Tas calibration 58 56 Measured pulp yield (%) 54 52 50 2 = 0.70 R p 48 SEP= 4.60 RPD p = 0.37 46 46 48 50 52 54 56 58 NIR-predicted pulp yield (%) Source: SCHIMLECK, L.R.; KUBE, P.D.; RAYMOND, C.A.; MICHELL, A.J.; FRENCH, J. 2005: Estimation of whole-tree kraft pulp yield of Eucalyptus nitens using near infrared spectra collected from increment cores. Can. J. For. Res. 35: 2797-2805 . — 15 —

PPY for Gog (Tasmania) using Northern Tas calibration 58 56 Measured pulp yield (%) 54 52 2 = 0.77 R p 50 SEP = 1.03 RPD p = 1.65 48 48 50 52 54 56 58 NIR-predicted pulp yield (%) Source: SCHIMLECK, L.R.; KUBE, P.D.; RAYMOND, C.A.; MICHELL, A.J.; FRENCH, J. 2005: Estimation of whole-tree kraft pulp yield of Eucalyptus nitens using near infrared spectra collected from increment cores. Can. J. For. Res. 35: 2797-2805 . — 16 —

Sample selection How to select which samples to add to the calibration? • Select trees that represent different diam classes, provenances, families, clones, site conditions etc. • Use an existing calibration to predict the property of interest and select samples that encompass the range • Analyse the spectra to identify unique samples • Selected samples are analysed and used to update the existing calibration (small number required) — 17 —

Whole-tree calibrations based on core spectra Whole-tree data and NIR spectra from cores used to develop wood property calibrations = non destructive estimation of wood properties • Schimleck et al. (2006) – calibrations based on NIR spectra from milled whole-tree chips and cores from 0.65 and 1.30 m provided similar results • Similar findings for hybrid poplars (western USA) and E. nitens (Tasmania) — 18 —

Comparison of Aracruz calibrations 1 0.8 0.6 whole-tree R 2 0.65 m 1.30 m 0.4 0.2 0 d n y e s s t g n l i i e n n s r a i o g n a y s C i e h l o p D C l t a l c n u i t H e P f o i P c T O e a p N S Source: SCHIMLECK, L.R.; REZENDE, G.D.S.P.; DEMUNER, B.J.; DOWNES, G.M. 2006: Estimation of whole-tree wood quality traits using near infrared spectra collected from increment cores. Appita J. 59: 231-236 . — 19 —

Hybrid poplar – core versus whole-tree 58 57 Increment cores Lab determined pulp yield (%) 56 59 55 58 Lab determined pulp yield (%) 54 57 5 factors 53 R 2 = 0.96 56 SEC = 0.35 55 52 52 53 54 55 56 57 58 54 NIR fitted pulp yield (%) 6 factors R 2 = 0.90 53 Whole-tree chips SEC = 0.55 52 52 53 54 55 56 57 58 59 NIR fitted pulp yield (%) Source: SCHIMLECK, L. R.; PAYNE, P.; WEARNE, R. H. 2005: Determination of important pulp properties of hybrid poplar by near infrared spectroscopy. Wood and Fiber Science 37 : 462-471. — 20 —

Summary of the calibration options Option Advantages Disadvantages Existing calibration * Minimal cost as no additional * Yield may be under or over pulping is required estimated * Rankings generally OK * Able to identify majority of top trees Enhanced calibration * Estimated yield closer to true * Some additional pulping yield required (minimal) * Improved ranking and identification of top trees Site specific calibration * Most accurate estimate of yield * Maximal cost as all trees * Most accurate rankings must be pulp tested Source: SCHIMLECK, L.R.; KUBE, P.D.; RAYMOND, C.A.; MICHELL, A.J.; FRENCH, J. 2005: Estimation of whole-tree kraft pulp yield of Eucalyptus nitens using near infrared spectra collected from increment cores. Can. J. For. Res.35 : 2797-2805 — 21 —

Estimation of wood properties of radial strips • NIR spectra collected from radial strips (10 mm) • Air-dry density • Microfibril angle • Estimated stiffness • Tracheid morphology • Tracheid length • Cellulose • Lignin — 22 —