This Is AuburnElectronic Theses and Dissertations

Valorization of Loblolly Pine (Pinus taeda) Downed Timber: Degradation and Recovery of Natural Polymers to Improve Bioeconomy Strategies




Hernandez-Diaz, Javier Abraham

Type of Degree

PhD Dissertation


Forestry and Wildlife Science

Restriction Status


Restriction Type


Date Available



In the aftermath of events such as hurricanes, downed timber's economic impact can reach billions. Accurate forecasting of stumpage prices post-events is crucial yet challenging due to data nature. This study innovatively applies wavelet analysis in forestry economic analysis to uncover relationships between timber market indices and hurricane seasons. Combining traditional correlation and wavelet coherence analysis deepens the understanding of timber market dynamics and the effects of hurricanes. The study highlights recent advancements in wavelet methodology, leveraging open-source R packages like WaveletComp and Wavelet-ARIMA. The Wavelet-ARIMA model effectively reduces noise, enhancing prediction accuracy across an extensive dataset encompassing various indices. Simultaneously, the study investigates hurricane-downed timber degradation in Alabama using near-infrared spectroscopy (NIR) and acoustic technology. Analyzing 30 loblolly pine trees, the research focuses on wood composition analysis, employing nonlinear techniques, smoothing optimization, and first derivative as a mathematical pretreatment, coupled with Box-Behnken (BB) experimental design. Utilizing 15 core samples, the models demonstrate efficiency comparable to complete sets, showcasing the potential for resource-efficient wood composition prediction. Spectral pretreatment investigations underscore the first derivative's efficacy and the balanced distribution of explained variance. Support Vector Machines (SVM) models exhibit superior predictive performances, particularly with a polynomial kernel. This innovative approach, combining reduced sample sizes and simplified spectral treatments, not only presents a promising avenue for wood composition prediction but also offers streamlined methodologies for scalability in forestry and wood industry practices, with implications for research and practical applications. Moreover, the study unveils distinct temporal patterns in sound-wave propagation and NIR measurements. NIR data’s principal component analysis (PCA) captures temporal phases, while transverse sound-wave measurements indicate consistent stress wave velocity variations. Thermogravimetric analysis (TGA) reveals significant shifts, emphasizing temporal dynamics, and chemical characterization highlights variations in lignin and carbohydrate fractions. The findings underscore the dynamic degradation process of hurricane-downed timber, emphasizing potential applications in timber quality assessment and biorefinery operations. Contributing to resilient and sustainable timber utilization post-natural disasters, the study enriches understanding of composition changes over time and the weathering process. Furthermore, the study delves into the weathering effects on downed timber over 12 months, mainly focusing on lignin and carbohydrate composition changes. The model study with harvested loblolly pine trees reveals gradual increases in Klason lignin content over time, indicating potential improvements in recovery operations. Changes in Fourier transform infrared (FTIR) spectra and Thermogravimetric analysis (TGA) demonstrate alterations in chemical composition, structure, and thermal properties of co-solvent enhanced lignin fractionation (CELF) lignin samples. Differential scanning calorimetry (DSC) analysis provided specific glass transition temperature (Tg) values, while Gel-permeation chromatography (GPC) indicated differences in molecular weight distribution consistent with expected natural degradation. Nuclear magnetic resonance (NMR) of the cell wall composition and CELF lignin obtained corroborate the observations. This comprehensive investigation contributes to understanding the intricate weathering effects on timber, offering valuable insights for sustainable utilization and recovery operations post-natural disasters. The consistency in lignin quality suggests the robustness and reliability of the CELF process in effectively isolating lignin from different stages of timber degradation. The process appears to be resilient to variations in the structural integrity and chemical composition of the starting material, ensuring that the resulting lignin maintains similar characteristics regardless of the initial state of the downed timber.