Date of Award

Fall 12-11-2021

Degree Type

Dissertation

Degree Name

Doctor of Philosophy - Forestry

Department

Forestry

First Advisor

Brian P. Oswald

Second Advisor

Alyx S. Frantzen

Third Advisor

I-Kuai Hung

Fourth Advisor

Yuhui Weng

Abstract

East Texas’ diverse landscape can present year-round wildfire seasons that can be influenced by seasonal and regional differences in climate and physiography. Greater insight into the fundamental thermal behavior of wildland fuels can aid in fire behavior prediction and development of fire-resistant plant lists. This study focused on estimating seasonal and regional flammability characteristics of five evergreen species: yaupon (Ilex vomitoria), Chinese privet (Ligustrum sinense), greenbrier (Smilax spp.), eastern red cedar (Juniperus virginiana), and escarpment live oak (Quercus fusiformis); and two deciduous species: Chinese tallow (Triadica sebifera) and southern red oak (Quercus falcata). Live foliar and small diameter branch wood samples were collected in the Pineywoods, Post Oak Savannah, and Blackland Prairie Ecoregions during the dormant (February) and growing (August) season. Oxygen bomb calorimetry (OBC) and proximate analyses estimated ash-free net heat content (NHC-AF; MJ kg-1) and proportions of volatile matter (VM%), fixed carbon (FC%), and ash percent (ash%). Pyrolytic and oxidative thermogravimetric analyses (TGA) estimated model-free activation energies (Ea(s)), relative spontaneous ignition temperature (RSIT; °C), gas-phase maximum mass loss rate (GP-MMLR; % min-1), and gas-phase combustion duration (GP-CD; min.). Greater mean VM% was a general indicator of greater mean NHC-AF(s) and GP-MMLR(s). All foliar NHC-AF(s), RSIT(s), and GP-MMLR(s) were significantly different with respect to species, season, and ecoregion. Mean regional GP-MMLR(s) were consistently greater in the growing season. The Post Oak Savannah and Blackland Prairie consistently yielded species with the greatest mean NHC-AF(s) and oxidative TGA values. Mean Ea(s) did not present any significant seasonal or regional trends.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Available for download on Tuesday, December 06, 2022

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