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Effects of fuel morphology on ember generation characteristics at the tree scale

Author(s): Tyler R. Hudson, Ryan B. Bray, David L. Blunck, Wesley G. Page, Bret W. Butler
Year Published: 2020
Description:

This work reports characteristics of embers generated by torching trees and seeks to identify the important physical and biological factors involved. The size of embers, number flux and propensity to ignite spot fires (i.e. number flux of ‘hot’ embers) are reported for several tree species under different combinations of number (one, three or five) and moisture content (11-193%). Douglas-fir (Pseudotsuga menziesii), grand fir (Abies grandis), western juniper (Juniperus occidentalis) and ponderosa pine (Pinus ponderosa) trees were evaluated. Embers were collected on an array of fire-resistant fabric panels and trays filled with water. Douglas-fir trees generated the highest average ember flux per kilogram of mass loss during torching, whereas grand fir trees generated the highest ‘hot’ ember flux per kilogram of mass loss. Western juniper produced the largest fraction of ‘hot’ embers, with ~30% of the embers generated being hot enough to leave char marks. In contrast, only 6% of the embers generated by ponderosa pine were hot enough to leave char marks. Results from this study can be used to help understand the propensity of different species of tree to produce embers and the portion of embers that may be hot enough to start a spot fire.

Citation: Hudson, Tyler R.; Bray, Ryan B.; Blunck, David L.; Page, Wesley G.; Butler, Bret W. 2020. Effects of fuel morphology on ember generation characteristics at the tree scale. International Journal of Wildland Fire 29(11):1042-1051. https://doi.org/10.1071/WF19182
Topic(s): Fire Behavior, Fuels, Wildland Urban Interface
Ecosystem(s): None
Document Type: Book or Chapter or Journal Article
NRFSN number: 22233
FRAMES RCS number: 62328
Record updated: Dec 7, 2020