Beetle-killed Lodgepole Pine Research Articles

Distinct fungal and bacterial responses to fire severity and soil depth across a ten-year wildfire chronosequence in beetle-killed lodgepole pine forests

Lodgepole pine forests are under threat due to wildfires of increasing severity and frequency coupled with tree mortality from insect outbreaks. Soil microbial communities, which drive biogeochemical cycles and partner in mycorrhizal symbiosis with lodgepole pines, play critical roles in the ability of these forests to survive and regenerate in the face of simultaneous global change threats. How soil microbial communities are influenced by fire severity and soil depth and how they recover over time in lodgepole pine forests with existing insect-driven mortality remains an open question. Here, we sampled two soil depths (0–5 and 5–15 cm) and various burn severities across a ten-year wildfire chronosequence in the Southern Rocky Mountains. We used qPCR of 18S and 16S rRNA genes to assess changes in fungal and bacterial abundance and ITS2 and 16S amplicon sequencing to assess fungal and bacterial richness and composition. Our results show that: 1) higher severity fires led to larger reductions of both fungal and bacterial abundance and richness, 2) the impact of fire on fungal and bacterial communities was modulated by soil depth, with more severe impacts in shallower soils 3) both fungal and bacterial communities exhibit a partial recovery of abundance and species richness in older fires, 4) fire severity is the main driver of fungal and bacterial community structure but its effect varied across time, 5) pyrophilous “fire-loving” fungi and bacteria exhibit an increased abundance in burned plots, particularly in recent fires, and 6) symbiotic ectomycorrhizal fungi are particularly hard hit by the compound effect of the beetle-driven tree mortality and wildfires. They exhibit a consistently low abundance and richness in the high severity plots which did not recover over time, and unburned plots have a depauperated ectomycorrhizal community.

Limited seed viability in long-dead serotinous lodgepole pine trees in the Southern Rockies, USA

Serotinous cones, those that remain closed until heated, confer post-disturbance resilience on many lodgepole pine forests throughout the Southern Rockies. The record-breaking extent of wildfires in northern Colorado and southern Wyoming in 2020 raised concerns about tree regeneration in areas where crown fires burned lodgepole pine stands that had experienced high levels of mortality during bark beetle outbreaks occurring more than a decade previously. We measured seed germination and assessed the relationship between cone age and seed viability for serotinous cones on beetle-killed lodgepole pine in eight stands adjacent to four of those wildfires (n = 1160 cones). On average, germination was 34 % with three viable germinants produced per cone. Seed germination declined and the proportion of cones that contained no seed increased across the age range of cones sampled (17–51 yrs at the time of the 2020 wildfires). Germination of seed retained within the canopy seedbank of these long-dead stands was roughly half of that measured on live or recently killed lodgepole pine. Though pre-fire tree mortality from bark beetles can exceed 90 % in this area, serotinous cones on the remaining live trees and cones buried in the soil seedbank will contribute viable lodgepole seeds for tree regeneration on some burned landscapes. The decreased germinant levels from these cones may regenerate into pine stands that are less dense than after harvesting, bark beetles or wildfire alone, but they will likely create forest structure within a range of conditions expected for this region.

Impacts of bark beetle-induced tree mortality on pyrogenic carbon production and heat output in wildfires for fire modeling and global carbon accounting

Forests store significant quantities of carbon, and accurate quantification of the fate of this carbon after fire is necessary for global carbon accounting. Pyrogenic carbon (PyC) encompasses various carbonaceous products of incomplete combustion formed during fires and has potential to act as a carbon sink for up to millennia, but current estimates of PyC production in wildfires vary widely. Northern hardwood forests have changed dramatically in recent decades due to insect epidemics, such as the bark beetle epidemic in the Rocky Mountain Region which has caused widespread mortality. This study assessed impacts of bark beetle-induced mortality on fuel pyrolysis kinetics, carbon partitioning of combustion products, and net heat output to aid in forest fire modeling and carbon accounting by comparing healthy and beetle-killed lodgepole pine tree boles burned in a 2018 forest fire in southeast Wyoming, USA with unburned boles. Results showed charring predominantly restricted to the bark and cambium. Significant differences between burned and unburned healthy and beetle-impacted bark/cambium compositions were identified, and PyC production and energy output were quantified. Charring extent and PyC content were found to be greater in beetle-impacted boles due to a reduction in bark/cambium resistance to heating and charring, with 80 times more PyC produced in a beetle-killed bark/cambium than in a healthy bark/cambium. Upon scale-up, total PyC production in the fire-affected area was estimated to be 0.71 GgPyC (82.5 kgPyC/ha). This was found to be significantly enhanced compared to an estimated PyC production of 0.036 GgPyC (4.12 kgPyC/ha) in a hypothetical healthy lodgepole pine ecosystem of equal area. The results of this investigation concluded that the 58% beetle-induced mortality in the Badger Creek Fire area resulted in 3 times more carbon released to the global atmosphere, 20 times more PyC retained onsite and 32% greater heat output during wildfire.

Snagfall the first decade after severe bark beetle infestation of high-elevation forests in Colorado, USA.

The persistence and fall rate of snags (standing dead trees) generated during bark beetle outbreaks have consequences for the behavior, effects, and suppression of potential wildfires, hazard tree and timber salvage operations, wildlife habitat, and numerous ecosystem processes. However, post-beetle snagfall dynamics are poorly understood in most forest types. We tagged standing live and dead lodgepole pine (Pinus contorta), subalpine fir (Abies lasiocarpa), and Engelmann spruce (Picea engelmannii), including beetle-killed pine snags following the peak of a recent mountain pine bark beetle outbreak in watersheds at the Fraser Experimental Forest in northcentral Colorado and sampled snagfall 10 and 12 years later. Bark beetle attacks began in 2003, peaked by 2006, and killed 78% of overstory lodgepole pine in 133 plots distributed across a range of stand and site conditions. Of those snags, only 17% fell between 2007 and 2018. Most snags broke at ground level, due to butt rot, and were oriented downhill. In contrast, snags that tipped up or snapped off above the ground were oriented with the prevailing winds. Equal numbers of snags fell singly and in multiple-tree groups, and equal numbers remained elevated rather than in contact with the ground. Lodgepole pine snagfall was 1.6-times higher on steep slopes (>40%) where dead pine density was higher, compared to flatter sites. Based on our findings and previous research, we estimate that one-half the beetle-killed lodgepole pine in high-elevation forests such as those at Fraser may fall within 15-20yr of beetle infestation, but that some pine snags are likely to persist for decades longer. Post-outbreak snagfall dynamics create a multiple-decade legacy of bark beetle outbreaks that will persist longer in high-elevation compared to lower-elevation forests.

Ex-situ catalytic fast pyrolysis of Beetle-killed lodgepole pine in a novel ablative reactor

Biomass fast pyrolysis involving the rapid thermal degradation of organic materials in the absence of oxygen is one of the most promising process for the sustainable production of alternative liquid fuels. However, it typically requires a relatively small particle size of dry biomass and the products need to be upgraded due to their high oxygen content. In this work, we employed a novel ablative fast pyrolysis reactor to convert as-received chips of Beetle killed lodgepole pine into vapors, and subsequently turned the vapors into aromatic hydrocarbons by ex-situ catalytic upgrade in a one pot synthesis system. We used pelletized HZSM-5 zeolite in a packed bed for the upgrade reaction and thoroughly characterized both fresh and spent catalysts by nitrogen sorption and electron microscopy. Our results revealed that a catalyst-to-biomass ratio of 4:1 and an upgrade temperature of 550 °C produced the lowest yield of coke (9.4 wt%) and the highest yield of aromatic hydrocarbons (3.5 wt%) with very high selectivity (94%) to benzene, toluene and xylene (BTX). We also analyzed the non-condensable gases to elucidate the deoxygenation mechanisms. This ablative reactor could be converted into a portable unit to produce alternative fuels without the need for biomass pre-treatment (i.e. grinding and drying) and transportation, creating a more sustainable and economically viable process for generating alternative fuels and specialty chemicals.

SPORL Pretreatment Spent Liquors Enhance the Enzymatic Hydrolysis of Cellulose and Ethanol Production from Glucose

This study investigated the recycle utilization of SPORL pretreatment spent liquor. Three lignosulfonates (LSs) were purified from the spent liquor of SPORL pretreated Beetle-killed lodgepole pine (BKLP), Poplar NE222 (NE222), and Douglas-fir (FS10). The structural characterization showed that the apparent molecular mass and sulfur content of NE222-LS were lowest, but the phenolic group content was highest. FS10-LS, from a pH profiling SPORL pretreatment, had the highest apparent molecular mass but medium sulfur and phenolic group content. The spectral analyses exhibited that the guaiacyl unit was the main structure in BKLP and FS10 LSs, while NE222-LS mainly contained both guaiacyl and syringyl units. Both LSs and SPORL pretreatment spent liquors were used as additives to enzymatic hydrolysis of Whatman paper and ethanol production from glucose. LSs and liquors, from SPORL pretreated BKLP and NE222, could obviously enhance the enzymatic saccharification. Nevertheless, LS and liquor from SPORL pretreated ...

Small Landowner Production of Pellets from Green, Beetle-Killed, and Burned Lodgepole Pine

To meet the growing need for raw materials to produce pellets and wood-based biofuels, trees killed by natural disturbances have increasingly been considered as potential feedstock in bioenergy development scenarios in the Western U.S. and Canada. While much research has focused on utilization of beetle-killed and fire-salvaged timber from federal lands in this region, small private landowners make up a large portion of land holdings in the Rocky Mountain Region and may also provide an important potential supply of uniform feedstock pellets in decentralized energy supply systems in the future. In this paper, we evaluated the quality of pellets produced from green, beetle-killed, and burned lodgepole pine with and without bark using a chipper, hammer mill, and pellet mill intended for use by small landowners. Results show that green, beetle-killed, and fire-salvaged lodgepole pine produced by small landowners, including material with bark, are suitable as feedstock for pellet production. Further, pellet quality can be varied through the blending of source lodgepole pine products when needed to meet pellet quality standards.

Overlapping Bark Beetle Outbreaks, Salvage Logging and Wildfire Restructure a Lodgepole Pine Ecosystem

The 2010 Church’s Park Fire burned beetle-killed lodgepole pine stands in Colorado, including recently salvage-logged areas, creating a fortuitous opportunity to compare the effects of salvage logging, wildfire and the combination of logging followed by wildfire. Here, we examine tree regeneration, surface fuels, understory plants, inorganic soil nitrogen and water infiltration in uncut and logged stands, outside and inside the fire perimeter. Subalpine fir recruitment was abundant in uncut, unburned, beetle-killed stands, whereas lodgepole pine recruitment was abundant in cut stands. Logging roughly doubled woody fuel cover and halved forb and shrub cover. Wildfire consumed all conifer seedlings in uncut and cut stands and did not stimulate new conifer regeneration within four years of the fire. Aspen regeneration, in contrast, was relatively unaffected by logging or burning, alone or combined. Wildfire also drastically reduced cover of soil organic horizons, fine woody fuels, graminoids and shrubs relative to unburned, uncut areas; moreover, the compound effect of logging and wildfire was generally similar to wildfire alone. This case study documents scarce conifer regeneration but ample aspen regeneration after a wildfire that occurred in the later stage of a severe beetle outbreak. Salvage logging had mixed effects on tree regeneration, understory plant and surface cover and soil nitrogen, but neither exacerbated nor ameliorated wildfire effects on those resources.

Ecosystem Resilience and Limitations Revealed by Soil Bacterial Community Dynamics in a Bark Beetle-Impacted Forest.

ABSTRACTForested ecosystems throughout the world are experiencing increases in the incidence and magnitude of insect-induced tree mortality with large ecologic ramifications. Interestingly, correlations between water quality and the extent of tree mortality in Colorado montane ecosystems suggest compensatory effects from adjacent live vegetation that mute responses in less severely impacted forests. To this end, we investigated whether the composition of the soil bacterial community and associated functionality beneath beetle-killed lodgepole pine was influenced by the extent of surrounding tree mortality. The most pronounced changes were observed in the potentially active bacterial community, where alpha diversity increased in concert with surrounding tree mortality until mortality exceeded a tipping point of ~30 to 40%, after which diversity stabilized and decreased. Community structure also clustered in association with the extent of surrounding tree mortality with compositional trends best explained by differences in NH4+ concentrations and C/N ratios. C/N ratios, which were lower in soils under beetle-killed trees, further correlated with the relative abundance of putative nitrifiers and exoenzyme activity. Collectively, the response of soil microorganisms that drive heterotrophic respiration and decay supports observations of broader macroscale threshold effects on water quality in heavily infested forests and could be utilized as a predictive mechanism during analogous ecosystem disruptions.

Estimating Aboveground Tree Biomass for Beetle-Killed Lodgepole Pine in the Rocky Mountains of Northern Colorado

Estimating Aboveground Tree Biomass for Beetle-Killed Lodgepole Pine in the Rocky Mountains of Northern Colorado

Mechanisms of population limitation in the southern red-backed vole in conifer forests of western North America: insights from a long-term study

Our goals were to characterize multiannual population changes of the southern red-backed vole (Myodes gapperi) to determine potential cycling behavior, and to specify the possible causes of these changes. We analyzed a detailed, 21-year record of changes in abundance of M. gapperi in late successional coniferous forest in southern British Columbia, Canada, from 1995 to 2015. We evaluated 3 hypotheses (H), namely that population changes are related to: (H1) changes in food supply from cone crops of coniferous trees; (H2) changes in forest habitat associated with beetle-killed lodgepole pine (Pinus contorta) trees; and (H3) territorial reorganization leading to breeding season declines in abundance. There were 3 cyclic population fluctuations (6- to 7-year periodicity) where red-backed voles reached mean fall numbers of 19–25, 15–16, and 26–27 per ha, respectively; in contrast, only 2–5 voles per ha occurred during population lows. Breeding season declines in abundance occurred in 17 of 21 years, with particularly precipitous drops ranging from 49% to 69% loss of voles. M. gapperi had more successful pregnancies, juvenile recruits, and adult recruits in the high than in the low population years. Mean index of early juvenile survival was 22% higher in low than high population years. Mean summer survival (58%) was consistently lower than that in winter (83%). Population increases were positively related to cone crops of 3 coniferous tree species. Thus, H1 was partially supported in 3 of 4 seedfall events. Positive changes in forest habitat, resulting from seed rain as a food supply and fallen debris from beetle-killed pine trees as cover, may have supported high numbers of voles in 2011–2012 (H2). A spring reorganization event limited the number of breeding animals by density-dependent inhibition of maturation and survival of juvenile voles, and led to breeding season declines (H3). Rigorous field experiments are needed to test these hypotheses and their interactions as mechanisms driving population change.

Biochars Reduce Mine Land Soil Bioavailable Metals.

Biochar has been proposed as an amendment to remediate mine land soils; however, it could be advantageous and novel if feedstocks local to mine land sites were used for biochar production. Two different feedstocks (pine beetle-killed lodgepole pine [] and tamarisk [ spp.]), within close proximity to mine land-affected soils, were used to create biochars to determine if they have the potential to reduce metal bioavailability. Four different mine land soils, contaminated with various amounts of Cd, Cu, Pb, and Zn, received increasing amounts of biochar (0, 5, 10, and 15% by wt). Soil pH and metal bioavailability were determined, and the European Community Bureau of Reference (BCR) sequential extraction procedure was used to identify pools responsible for potential shifts in bioavailability. Increasing biochar application rates caused increases in soil pH (initial, 3.97; final, 7.49) and 55 to 100% (i.e., no longer detectable) decreases in metal bioavailability. The BCR procedure supported the association of Cd with carbonates, Cu and Zn with oxyhydroxides and carbonates, and Pb with oxyhydroxides; these phases were likely responsible for the reduction in heavy metal bioavailability. This study proved that both of these feedstocks local to abandoned mining operations could be used to create biochars and reduce heavy metal bioavailability in mine land soils.

Preparation of Fe-cored carbon nanomaterials from mountain pine beetle-killed pine wood

The mountain pine beetle-killed lodgepole pine (Pinus contorta) wood treated with iron (III) nitrate solution was used for the preparation of Fe-cored carbon nanomaterials (Fe-CNs) under various carbonization temperatures. The carbonization yield of Fe-treated sample (5% as Fe) was always 1–3% higher (after ash compensation) than that of the non-treated samples heated at the same condition. The lowest carbonization temperature required to produce Fe-CNs was 700°C. The carbon shell was composed of 30–40 well-aligned layers of graphitic carbon nanostructure. The iron captured by graphitic layers was assumed to be iron carbides and/or α-Fe and γ-Fe. This study indicates that at least 700°C of carbonization temperature is needed for the production of Fe-CNs and the mountain pine beetle-killed pine wood can be a carbon source for the production of Fe-CNs.

Determining the Processed Cut Stock Recovery Rate from Standing Dead Beetle-Killed Lodgepole Pine Timber

Abstract Colorado's forests have been decimated by a mountain pine beetle outbreak. The mountain pine beetle introduces a blue-stain fungus into the trees, lowering the economic value of the wood. As a result, forest product manufacturing opportunities using beetle-killed trees are limited. One possibility is to use beetle-killed trees to make cut stock, which is lumber that has been cut into specified length, width, and thickness requirements from a cant, lumber, or glued-up panels. The White River Conservation District commissioned this study to determine if a relationship existed between the amount of time beetle-killed trees remain standing dead and the recovery rate for cut stock material from those trees. Conducted in north-central Colorado and south-central Wyoming, this study found that enough material does exist in beetle-killed lodgepole pine trees to produce cut stock but that a tree's diameter at breast height is a better predictor for the cut stock recovery rate from the logs rather than the time spent standing dead on the stump. Given the increasing likelihood that beetle-killed trees will blow down as time passes, incentives for increased beetle-killed wood utilization should be developed quickly.

Species composition influences management outcomes following mountain pine beetle in lodgepole pine-dominated forests

Mountain pine beetle outbreaks have killed lodgepole pine on more than one million hectares of Colorado and southern Wyoming forest during the last decade and have prompted harvest operations throughout the region. In northern Colorado, lodgepole pine commonly occurs in mixed stands with subalpine fir, Engelmann spruce, and aspen. Variation in tree species composition will influence structure, fuel profiles and fire hazard as forests recover from bark beetle outbreaks, and this diversity has implications for design and implementation of fuel reduction treatments. We used stand inventory data to predict forest structure and fuel loads starting after needle fall through one century after bark beetle infestation for three lodgepole pine-dominated forest types (pine, pine with aspen, pine with fir and spruce), and compared simulated effects of no-action and fuel reduction treatments (thinning, broadcast burning). In pine stands mixed with significant density of fir and spruce, the high canopy bulk density and low canopy base height increases passive and active crown fire hazards compared to stands with few shade tolerant trees. In contrast, stands of pine mixed with aspen had lower canopy bulk density and active crown fire hazard. All three forest types had high snag and coarse woody debris loads. Thinning and broadcast burning reduced canopy fuels in all forest types for several decades, but had the largest effect in forests with abundant fir. Burning temporarily reduced fine woody fuel, and caused a longer-term reduction in coarse wood and duff. Overall, these simulations indicate that management aimed at reducing canopy fuels in beetle-killed lodgepole pine forests should prioritize stands with high densities of overstory and understory fir and spruce. Forest growth following treatment requires frequent stand manipulation (as often as every 20years) to maintain reduced fuel loads, and since such treatments are expensive and likely not analogous to natural disturbances these activities are most appropriate where resource and infrastructure protection and human safety concerns are high.

Fast pyrolysis of beetle-killed trees

In this article, we propose beetle-killed lodgepole pine (BKLP) as a feedstock for fast pyrolysis due to its low moisture and high energy content. To the best of our knowledge, no previous studies on fast pyrolysis of beetle-killed trees have been reported. Samples of healthy lodgepole pine and three decay-stage BKLPs were used as feedstock to investigate the effects of the decay stage on the performance of both non-catalytic and catalytic fast pyrolysis using a Py–GC/MS. Compared to the healthy tree, BKLPs were found to have slightly more extractives and less lignin. The decay stage, however, did not affect the product yield and selectivity for both non-catalytic and catalytic fast pyrolysis. A variety of oxygenated compounds were produced in non-catalytic fast pyrolysis, but most of those were converted into aromatic hydrocarbons in the presence of HZSM-5. For non-catalytic fast pyrolysis, the yield of char decreased from 22wt.% to 11wt.% as the pyrolysis temperature increased from 450°C to 650°C. The average HHV of volatile compounds was found to be around 26MJ/kg. For the catalytic fast pyrolysis, the yield of hydrocarbons was as high as 40wt.%, and the yield of char was as low as 5wt.%. The average HHV of volatiles was found to be about 41MJ/kg, which is close to the HHV of commercial gasoline and diesel (∼46MJ/kg). A high yield of toluene (11wt.%) and xylenes (9wt.%) was also observed in the catalytic fast pyrolysis process. Our work suggests that beetle-killed trees are a good feedstock for fast pyrolysis, because the bio-oil derived from the trees that have been dead for four years showed the same quality as that from the healthy trees.

Bioconversion of Beetle-Killed Lodgepole Pine Using SPORL: Process Scale-up Design, Lignin Coproduct, and High Solids Fermentation without Detoxification

Mountain pine beetle killed Lodgepole pine (Pinus contorta Douglas ex Loudon) wood chips were pretreated using an acidic sulfite solution of approximately pH = 2.0 at a liquor to wood ratio of 3 and sodium bisulfite loading of 8 wt % on wood. The combined hydrolysis factor (CHF), formulated from reaction kinetics, was used to design a scale-up pretreatment on 2000 g wood chips at a relatively low temperature of 165 °C that reduced furan formation and facilitated high solids saccharification and fermentation. The pretreated solids and liquor were disk milled together to result in a biomass whole slurry of 25% total solids. The whole biomass slurry was directly used to conduct simultaneous enzymatic saccharification and combined fermentation (SSCombF) using a commercial cellulase and Saccharomyces cerevisiae YRH400 without detoxification. A terminal ethanol titer of 47.1 g L–1 with a yield of 306 L (tonne wood)−1, or 72.0% theoretical, was achieved when SSCombF was conducted at an unwashed solids loading of...

Salvage harvest effects on advance tree regeneration, soil nitrogen, and fuels following mountain pine beetle outbreak in lodgepole pine

The extent and severity of recent native bark beetle (Dendroctonae) outbreaks in western North America have created a pressing need for forest managers to understand potential consequences of post-disturbance management. For example, post-outbreak timber harvest (i.e., salvage harvest) could alter future forest development, productivity and susceptibility to subsequent disturbance. To assess the potential for such consequences, we measured first-year effects of post-outbreak timber harvest on tree regeneration, soil nitrogen (N) availability and fuels by using a paired and replicated before–after-control-impact (BACI) experimental design with eight pairs of 0.25-ha plots in beetle-killed lodgepole pine (Pinus contorta var. latifolia) in Greater Yellowstone (Wyoming, USA). Post-outbreak timber harvest reduced total (live +dead) lodgepole pine basal area by 90%. Total sapling density (advance regeneration) declined by about 50% following harvest, with tall (30–140cm) saplings declining most, but mean post-harvest sapling density still exceeded 1600 stems ha−1. Relative species density was unaffected and remained dominated by lodgepole pine. Soil temperature at the litter–soil interface was warmer during summer in harvested stands, and soil NO3- concentration increased with harvest relative to untreated plots. Soil NH4+ concentration and resin bag N accumulation increased through time in all beetle-killed plots and were not affected by harvest. Following harvest, dead woody surface fuels in all size categories doubled, and canopy fuel load and canopy bulk density both were reduced; dead fuel depth, duff depth, and canopy base height did not differ between untreated and harvested plots. Harvest did reduce canopy fuels, but the natural progression of needle shedding after beetle-kill accounted for 25–40% of this total canopy fuel reduction. Salvage harvest seems unlikely to alter post-outbreak successional trajectories in these lodgepole pine forests. However, the altered fuel complex (immediate increase in dead woody surface fuels and expected long-term reduction in large-diameter fuels) in harvested plots could cause subsequent fire behavior and effects to differ between harvested and untreated stands.

The Legacy of Attack: Implications of High Phloem Resin Monoterpene Levels in Lodgepole Pines Following Mass Attack by Mountain Pine Beetle, <I>Dendroctonus ponderosae</I> Hopkins

The mountain pine beetle (Dendroctonus ponderosae Hopkins) is the most serious pest of pines (Pinus) in western North America. Host pines protect themselves from attack by producing a complex mixture of terpenes in their resin. We sampled lodgepole pine (Pinus contorta variety latifolia) phloem resin at four widely separated locations in the interior of British Columbia, Canada, both just before (beginning of July) and substantially after (end of August) the mountain pine beetle dispersal period. The sampled trees then were observed the next spring for evidence of survival, and the levels of seven resin monoterpenes were compared between July and August samples. Trees that did not survive consistently had significantly higher phloem resin monoterpene levels at the end of August compared with levels in July. Trees that did survive mainly did not exhibit a significant difference between the two sample dates. The accumulation of copious defense-related secondary metabolites in the resin of mountain pine beetle-killed lodgepole pine has important implications for describing the environmental niche that the beetle offspring survive in as well as that of parasitoids, predators, and other associates.

Efficient ethanol production from beetle-killed lodgepole pine using SPORL technology and Saccharomyces cerevisiae without detoxification

This study applied Sulfite Pretreatment to Overcome Recalcitrance of Lignocelluloses (SPORL) to evaluate the potential of mountain pine beetle-killed lodgepole pine for ethanol production using conventional Saccharomyces cerevisiae without hydrolysate detoxification. The results indicate that the beetle-killed trees are more susceptible to SPORL pretreatment than live trees in addition to having enriched glucan and mannan content as reported in the literature. Ethanol yields of 200 and 250 L/metric ton wood were achieved from a live tree and a dead tree (four years after infestation) without process optimization. Ethanol yield of 220 L/metric ton of wood was obtained from a downed tree with more advanced decomposition, which is approximately 10% more than that from a corresponding live tree. Process mass and energy balance analyses suggest that net ethanol energy output (before distillation, lignin energy excluded) from the decomposing tree was approximately 3.2 GJ/metric ton wood, which is 23% more than that from a corresponding live tree. The study demonstrated the robustness of the SPORL process and the utility of beetle-killed trees for cellulosic ethanol production even after many years post mortality.