Emissions of BVOC from lodgepole pine in response to mountain pine beetle attack in high and low mortality forest stands

Abstract

Abstract. In this screening study, biogenic volatile organic compound (BVOC) emissions from intact branches of lodgepole pine (Pinus contorta) trees were measured from trees at two forested sites that have been impacted differently by the mountain pine beetle (MPB), with one having higher mortality and the other with lower mortality. Differences in the amounts and chemical diversity of BVOC between the two sites and from apparently healthy trees versus trees in different stages of MPB attack are presented, as well as (for one site) observed seasonal variability in emissions. A brief comparison is made of geological and climatic characteristics as well as prior disturbances (both natural and man-made) at each site. Trees sampled at the site experiencing high MPB-related tree mortality had lower chemodiversity in terms of monoterpene (MT) emission profiles, while profiles were more diverse at the lower-mortality site. Also at the higher-mortality site, MPB-infested trees in various stages of decline had lower emissions of sesquiterpenes (SQTs) compared to healthy trees, while at the site with lower mortality, MPB-survivors had significantly higher SQT emissions during part of the growing season when compared to both uninfested and newly infested trees. SQT profiles differed between the two sites and, like monoterpene and oxygenated VOC profiles, varied through the season. For the low-mortality site in which repeated measurements were made over the course of the early summer-late fall, higher chemical diversity was observed in early-compared to late-season measurements for all compound classes investigated (MT, oxygenated VOC, and SQT), with the amount of change appearing to correlate to the MPB status of the trees studied. Emissions of 2-methyl-3-buten-2-ol (MBO) had a distinct seasonal signal but were not much different between healthy or infested trees, except in trees with dead needles, from which emissions of this compound were negligible, and in late-season MPB survivors, in which they were higher than in newly infested or uninfested trees. Emissions of SQT were significantly higher in the MPB survivors during both mid-and late-season sampling at the low-mortality site. The changes in emissions could have implications for regional air quality and climate through changes in ozone and aerosol distributions, although this study was designed as a preliminary screening effort and not enough individuals were sampled for all of the observed differences to be statistically demonstrated. Despite this, the compelling differences in emissions observed between the sites and individual trees with differing MPB-infestation statuses and the potential impacts these have on regional atmospheric chemistry argue for further research in this topic.

Terpenoid emissions from fully grown east Siberian <i>Larix cajanderi</i> trees

“…Haapanala et al (2009) found large α-farnesene emissions from mountain birches in northern Sweden two years after an outbreak of autumnal moth; when the measurements were repeated the following year, α-farnesene was no longer observed. However, in the case of mechanical or herbivore-attack-induced stress, one expects not only different rates of emissions but also different emission spectra, which were not observed in this study (Haapanala et al, 2009;Duhl et al, 2013). The similar emission spectra of trees A and B do not support the hypothesis that either of the trees would have been more stressed than the other.…”

The impact of bark beetle infestations on monoterpene emissions and secondary organic aerosol formation in western North America

“…The large differences between the pine and spruce scenarios illustrate the large species-variability in response to beetle attack and the uncertainties that still surround the impact of beetles on atmospheric composition. Duhl et al (2013) seek to quantify the impacts of MPB on monoterpene emissions from lodgepole pine as well as changes over time; however, their results for a limited number of trees are inconclusive and appear to be dominated by tree-to-tree variability. Beetle attack generally occurs during the summer months when monoterpene emissions are highest (e.g.…”

Simulating the recent impacts of multiple biotic disturbances on forest carbon cycling across the United States

“…In contrast to non-lethal defoliation, tree mortality results in larger and more sustained negative effects on productivity. In addition to C cycle impacts, BDs have also been shown to alter forest dynamics and composition (Costilow, Knight, & Flower, 2017;Crowley, Lovett, Arthur, & Weathers, 2016;Temperli, Veblen, Hart, Kulakowski, & Tepley, 2015), energy, water, and nitrogen (N) fluxes (Anderegg et al, 2016;Bright, Hicke, & Meddens, 2013;Chen et al, 2015), as well as the emission of biogenic volatile organic compounds to the atmosphere (Berg et al, 2013;Duhl, Gochis, Guenther, Ferrenberg, & Pendall, 2013). As a consequence, affected forests might function as a C source over few years (Brown et al, 2012) up to decades , with magnitude and duration depending on initial tree mortality fraction and the speed of decomposition and regrowth (Anderegg et al, 2016).…”