Event Title

Why Does Exposure to Wildfire Smoke Alter Tree Chemistry?

Location

USU Eccles Conference Center

Event Website

http://www.restoringthewest.org/

Abstract

We observed a large spike in terpene emissions and a reduction in concentration of within-needle terpenes while sampling volatile organic compounds (VOCs) from Great Basin bristlecone pine, GBBP (Pinus longeava Bailey) and limber pine (Pinus flexilis James) during the Carpenter 1 Fire (July, 2013) on Mount Charleston northwest of Las Vegas, Nevada. We hypothesize that exposure to smoke induced the observed changes in terpene emissions and concentrations. We tested this hypothesis by applying smoke to trees and measuring subsequent changes to VOCs and foliage flammability. Smoke from smoldering conifer needles was applied hourly (5 min per hour) to an apical branch (45 cm) of four GBBP and four limber pines using commercial bee smokers. VOCs were then measured from each branch and from four unsmoked control trees from each of the two species (GBBP and limber). We found that VOCs from the branches exposed to smoke increased approximately 3 fold over the controls during the 42 hour test period. In the laboratory, foliar fuel moisture and flammability of the needles from each treatment was measured (fuel moisture, time to ignition, duration of flaming, temperature at ignition, and maximum temperature). Of the variables measured only fuel moisture showed statistically significant differences. To determine if observed VOC response is unique to conifers we repeated the experiment using tomato plants (Solanum esculentum). Smoke-induced changes in VOCs may have important consequences for tree flammability and increased exposure to smoke may stress trees affecting the tree’s natural defenses.

Comments

Curtis Gray is a PhD Student, Utah State University.

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Why Does Exposure to Wildfire Smoke Alter Tree Chemistry?

USU Eccles Conference Center

We observed a large spike in terpene emissions and a reduction in concentration of within-needle terpenes while sampling volatile organic compounds (VOCs) from Great Basin bristlecone pine, GBBP (Pinus longeava Bailey) and limber pine (Pinus flexilis James) during the Carpenter 1 Fire (July, 2013) on Mount Charleston northwest of Las Vegas, Nevada. We hypothesize that exposure to smoke induced the observed changes in terpene emissions and concentrations. We tested this hypothesis by applying smoke to trees and measuring subsequent changes to VOCs and foliage flammability. Smoke from smoldering conifer needles was applied hourly (5 min per hour) to an apical branch (45 cm) of four GBBP and four limber pines using commercial bee smokers. VOCs were then measured from each branch and from four unsmoked control trees from each of the two species (GBBP and limber). We found that VOCs from the branches exposed to smoke increased approximately 3 fold over the controls during the 42 hour test period. In the laboratory, foliar fuel moisture and flammability of the needles from each treatment was measured (fuel moisture, time to ignition, duration of flaming, temperature at ignition, and maximum temperature). Of the variables measured only fuel moisture showed statistically significant differences. To determine if observed VOC response is unique to conifers we repeated the experiment using tomato plants (Solanum esculentum). Smoke-induced changes in VOCs may have important consequences for tree flammability and increased exposure to smoke may stress trees affecting the tree’s natural defenses.

https://digitalcommons.usu.edu/rtw/2015/Posters/14