Within Tree Variation of Lignin, Extractives, and Microfibril Angle Coupled With the Theoretical and Near Infrared Modeling of Microfibril Angle

Abstract

SUMMARYA theoretical model was built predicting the relationship between microfibril angle and lignin content at the Angstrom (A) level. Both theoretical and statistical examination of experimental data supports a square root transformation of lignin to predict microfibril angle. The experimental material used came from 10 longleaf pine (Pinuspalustris) trees. Klason lignin (n=70), microfibril angle (n=70), and extractives (n=100) were measured and reported at different ring numbers and heights. All three traits were strongly influenced by ring age from pith while microfibril angle and extractives exhibited more of a height effect than lignin. As such, the multivariate response of the three traits were different in the axial direction than the radial direction supporting that care needs to be taken when defining juvenile wood within the tree. The root mean square error of calibration (RMSEC) for microfibril angle of the theoretical model (RMSEC = 9.8) was almost as low as the least squares regression model (RMSEC = 9.35). Microfibril angle calibrations were also built from NIR absorbance and showed a strong likeness to theoretical and experimental models (RMSEC = 9.0). As a result, theoretical and experimental work provided evidence that lignin content played a significant role in how NIR absorbance relates to microfibril angle. Additionally, the large variation in extractives content coupled with sampling procedure proved important when developing NIR based calibration equations for lignin and microfibril angle.

High Throughput Screening of Elite Loblolly Pine Families for Chemical and Bioenergy Traits with Near Infrared Spectroscopy

“…The researchers noted the innerwood contained a relatively higher amount (i.e., 5.2% to 7.0%) of alcohol-benzene extractives compared to the outerwood (i.e., 2.5% to 4.5%). Similar results where the extractives content of Pinus palustris decreased as one moved from the pith towards the bark, and also from the butt higher up the stem have been reported [34]. As can be seen in Table 4, the differences in the extractives content between the families on a site is a function of genotypic variation; whereas differences within a single family on the two sites is a response to environmental conditions such as the presence of biological degraders or silvicultural treatments that aim to increase tree growth [35,36].…”

Rapid analysis of the microfibril angle of loblolly pine from two test sites using near-infrared analysis

“…A larger increase in CV (13.0%-21.7%) was obtained from rings 5 to 20 of latewood fibres from the earlier study by Mott et al (2002) with the CV reaching 34.1% for growth ring 40 . Via et al (2007) reported a greater range of CVs (15%-55%) in a MFA study of 41-yearold longleaf pine trees, ranging from 15.7% (growth ring 4) to 55.8% (growth ring 16). It was noted that the GP258 earlywood calibration provided a slightly higher mean MFA (32.3°) than its latewood counterpart (30.9°).…”

“…In these studies, spectra were collected from the radial-longitudinal face of wooden strips cut from increment cores, and averaged over 10 mm increments, and as a consequence, it was not possible to follow the variation of MFA on an annual basis to observe the effects of silvicultural treatments. Inter-ring variability has been assessed by sectioning individual early wood and late wood rings from increment cores and collecting NIR spectra from the tangential face , Schimleck et al 2007, Via et al 2007, Hein et al 2010. Kelley et al (2004) obtained reasonable correlations with MFA from loblolly pine (Pinus taeda L.); however, only 72 total samples were used in the analysis.…”

Nonlinear multivariate modeling of strand mechanical properties with near-infrared spectroscopy

“…More importantly, the increase in model robustness with nonlinear modeling supports the supposition that prediction of MOR with NIR spectra may be nonlinear in relation. This may be due to a) the nonlinear relationship between density and spectra (Via 2010 b) the nonlinear covariance between wood chemistry, Fibre morphology, age, and spectra that is apparent (Via et al 2007(Via et al , 2009) and c) the nonlinear relationship between microfibril angle and lignin with higher polymer angles resulting in increased plastic deformation in lignin just prior to Fibre rupture, which results in an apparent nonlinear relationship between microfibril angle and MOR for southern pine and Douglas-fir (Pseudotsuga menziesii var. menziesii [Mirb.]…”

“…The effect of genetic control or silvicultural response is also strong but more limited than age effects. NIR signals have been shown to be sensitive to various traits under genetic and silviculture control including lignin, cellulose, hemicellulose, extractives, microfibril angle, and density (Schimleck et al 2002, Perez et al 2007, Via et al 2007, Isik et al 2011. Via et al (2005a) demonstrated that tracheid length could be predicted with NIR but as a function of age.…”