Rocky Mountain Research Station Publications

RMRS Online Publication - Journal Articles, External Publications, and Special Reports
Relationships between moisture, chemistry, and ignition of Pinus contorta needles during the early stages of mountain pine beetle attack


Jolly, W. Matt; Parsons, Russell A.; Hadlow, Ann M.; Cohn, Greg M.; McAllister, Sara S.; Popp, John B.; Hubbard, Robert M.; Negron, Jose F. 2012. Relationships between moisture, chemistry, and ignition of Pinus contorta needles during the early stages of mountain pine beetle attack. Forest Ecology and Management. 269: 52-59.

doi:10.1016/j.foreco.2011.12.022

Very little is known about how foliar moisture and chemistry change after a mountain pine beetle attack and even less is known about how these intrinsic foliar characteristics alter foliage ignitability. Here, we examine the fuel characteristics and ignition potential of Pinus contorta (lodgepole pine) foliage during the early stages of a mountain pine beetle attack. Foliar samples were taken periodically from multiple trees identified as green (healthy, unattacked), recently attacked, or red (dead). The fuel moisture content, chemical composition, and time to ignition of needles from each attack category were quantified. Foliar moisture contents varied by an order of magnitude between the attack categories and were lowest for red needles ( 12% on average), highest for green needles ( 109% on average), and most variable for needles of recently attacked trees. Dry matter proportions of fiber in the needles of attacked and red trees were nearly twice that of green needles. Starch and sugar levels were much lower in the needles of attacked and red trees than green trees. Crude fat contents also differed between the attack categories. Time to ignition was strongly related to time since beetle attack. Ignition times varied from as little as 11 s for red needles to 41 s for green needles. A combined model of foliar moisture content, fiber, and crude fat explained 92% of the variation in the foliar time to ignition. Results show that decreased moisture contents and changes in foliar chemistry increase the foliar flammability of mountain pine beetleattacked trees. This suggests that less heat would be required to ignite the foliage of attacked trees and thus crown fire potential may be higher in attacked stands as long as foliage is retained on the tree.

Keywords: fuel moisture, carbohydrates, crude fat, mountain pine beetle, flammability, crown fire


About PDFs: For best results, do not open the PDF in your Web browser. Right-click on the PDF link to download the PDF file directly to your computer. Click here for more PDF help.


Download Article
http://www.fs.fed.us/rm/pubs_other/rmrs_2012_jolly_w001.pdf

PDF File Size: 480 K


Title: RMRS Other Publications: Relationships between moisture, chemistry, and ignition of Pinus contorta needles during the early stages of mountain pine beetle attack
Electronic Publish Date: February 16, 2012
Last Update:
February 16, 2012

RMRS Publications | Order a publication | Contact Us