Tree mortality from fires, bark beetles, and timber harvest during a hot and dry decade in the western United States (2003–2012)

AbstractChanging forest disturbance regimes and climate are driving accelerated tree mortality across temperate forests. However, it remains unknown if elevated mortality has induced decline of tree populations and the ecological, economic, and social benefits they provide. Here, we develop a standardized forest demographic index and use it to quantify trends in tree population dynamics over the last two decades in the western United States. The rate and pattern of change we observe across species and tree size-distributions is alarming and often undesirable. We observe significant population decline in a majority of species examined, show decline was particularly severe, albeit size-dependent, among subalpine tree species, and provide evidence of widespread shifts in the size-structure of montane forests. Our findings offer a stark warning of changing forest composition and structure across the western US, and suggest that sustained anthropogenic and natural stress will likely result in broad-scale transformation of temperate forests globally.

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Spatiotemporal patterns of observed bark beetle-caused tree mortality in British Columbia and the western United States

Ecological Applications ◽

10.1890/11-1785.1 ◽

2012 ◽

Vol 22 (7) ◽

pp. 1876-1891 ◽

Cited By ~ 197

Author(s):

Arjan J. H. Meddens ◽

Jeffrey A. Hicke ◽

Charles A. Ferguson

Keyword(s):

United States ◽

British Columbia ◽

Bark Beetle ◽

Tree Mortality ◽

Spatiotemporal Patterns ◽

Western United States

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

Atmospheric Chemistry and Physics ◽

10.5194/acp-13-3149-2013 ◽

2013 ◽

Vol 13 (6) ◽

pp. 3149-3161 ◽

Cited By ~ 30

Author(s):

A. R. Berg ◽

C. L. Heald ◽

K. E. Huff Hartz ◽

A. G. Hallar ◽

A. J. H. Meddens ◽

...

Keyword(s):

United States ◽

British Columbia ◽

North America ◽

Bark Beetle ◽

Tree Mortality ◽

Secondary Organic Aerosol ◽

Organic Aerosol ◽

Western United States ◽

Western North America ◽

The Impact

Abstract. Over the last decade, extensive beetle outbreaks in western North America have destroyed over 100 000 km2 of forest throughout British Columbia and the western United States. Beetle infestations impact monoterpene emissions through both decreased emissions as trees are killed (mortality effect) and increased emissions in trees under attack (attack effect). We use 14 yr of beetle-induced tree mortality data together with beetle-induced monoterpene emission data in the National Center for Atmospheric Research (NCAR) Community Earth System Model (CESM) to investigate the impact of beetle-induced tree mortality and attack on monoterpene emissions and secondary organic aerosol (SOA) formation in western North America. Regionally, beetle infestations may have a significant impact on monoterpene emissions and SOA concentrations, with up to a 4-fold increase in monoterpene emissions and up to a 40% increase in SOA concentrations in some years (in a scenario where the attack effect is based on observed lodgepole pine response). Responses to beetle attack depend on the extent of previous mortality and the number of trees under attack in a given year, which can vary greatly over space and time. Simulated enhancements peak in 2004 (British Columbia) and 2008 (US). Responses to beetle attack are shown to be substantially larger (up to a 3-fold localized increase in summertime SOA concentrations) in a scenario based on bark-beetle attack in spruce trees. Placed in the context of observations from the IMPROVE network, the changes in SOA concentrations due to beetle attack are in most cases small compared to the large annual and interannual variability in total organic aerosol which is driven by wildfire activity in western North America. This indicates that most beetle-induced SOA changes are not likely detectable in current observation networks; however, these changes may impede efforts to achieve natural visibility conditions in the national parks and wilderness areas of the western United States.

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Faculty Opinions recommendation of Widespread increase of tree mortality rates in the western United States.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.1145180.602328 ◽

2009 ◽

Author(s):

Dennis Baldocchi

Keyword(s):

United States ◽

Tree Mortality ◽

Mortality Rates ◽

Western United States

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A Comparative Life-Cycle Assessment of Briquetting Logging Residues and Lumber Manufacturing Coproducts in Western United States

Applied Engineering in Agriculture ◽

10.13031/aea.12378 ◽

2018 ◽

Vol 34 (1) ◽

pp. 11-24 ◽

Cited By ~ 4

Author(s):

Sevda Alanya-Rosenbaum ◽

Richard D. Bergman ◽

Indroneil Ganguly ◽

Francesca Pierobon

Keyword(s):

United States ◽

Life Cycle Assessment ◽

Life Cycle ◽

Environmental Impacts ◽

Timber Harvest ◽

The United States ◽

Western United States ◽

Forest Residues ◽

Post Harvest ◽

Forest Residue

Abstract. Timber harvest activities in the western United States have resulted in large volumes of low- to no-value logging (forest) residues. Alternatives to pile-and-burning are needed to best utilize this material and to mitigate the resultant environmental impacts. Briquetting (densifying) forest residues near-woods is one such option and is the focus of this study. This study presents a cradle-to-grave life-cycle assessment (LCA) performed to evaluate the overall environmental impacts associated with briquetting post-harvest forest residues and dry sawmill residues (sawdust) in the Pacific Northwest (PNW) region of the United States. Environmental impacts resulting from the two briquette production systems were compared with firewood and propane production, which are common residential heating sources in rural areas of the PNW, on a per 1 MJ of useful energy for domestic heating. In the briquetted post-harvest forest residue system, the feedstock preparation stage had the largest share in global warming (GW) impact, mainly resulting from the drying process (69.5%), followed by transportation. Valorization of post-harvest forest residues, in combination with a briquetter, to produce a bioenergy carrier was revealed to be advantageous in smog, acidification, and eutrophication impact categories, with considerable environmental benefits from avoided pile-and-burn emissions. With all scenarios investigated, briquette production from post-harvest forest residues with high dryer efficiency showed lowest GW impact compared to briquetting sawmill residues and firewood supply chain. For a scenario analysis, LCA showed that using a diesel generator to support the forest residue briquetter operation resulted in 45% higher GW impact compared to use of a wood-gas-powered generator. Keywords: Bioenergy, Biomass densification, Briquette, Forest residues, Life-cycle assessment, Sawdust.

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