Slash Piles Research Articles

Cradle-to-gate life cycle analysis of slow pyrolysis biochar from forest harvest residues in Ontario, Canada

Climate change mitigation technologies have been a focus in reducing atmospheric carbon levels for the past few years. One such mitigation technology is pyrolysis, where biomass feedstocks are combusted at elevated temperatures for varying durations to produce three main products: biochar, bio-oil, and biogas. While bio-oil and biogas are typically used to produce energy via further combustion, biochar can be used in several different applications. Furthermore, using forest harvest residues as a feedstock for biochar production helps use excess biomass from the forestry industry that was previously assumed unmarketable. In our study, we combined forest carbon analysis modelling with cradle-to-gate life cycle emissions to determine the greenhouse gas emissions of biochar produced from forest harvest residues. We examined three collection scenarios, spanning two harvesting methods in one forest management unit in northern Ontario, Canada. From our analysis, we observed immediate reductions (− 0.85 tCO2eq·tbiochar−1 in year 1) in CO2-equivalent emissions (CO2eq) when producing biochar from forest harvest residues that would have undergone controlled burning, without considering the end use of the biochar. For the forest harvest residues that would remain in-forest to decay over time, producing biochar would increase overall emissions by about 6 tCO2eq·tbiochar−1. Throughout the 100-year timeframe examined–in ascending order of cumulative emissions–scenario ranking was: full tree harvesting with slash pile burn < full tree harvesting with slash pile decay < cut-to-length/tree-length harvesting.Graphical

Continuous In-woods Production of Biochar Using a Trailer-mounted Air Curtain Burner.

Fuel treatments and other forest restoration thinning practices aim to reduce wildfire risk while building forest resilience to drought, insects, and diseases and increasing aboveground carbon (C) sequestration. However, fuel treatments generate large amounts of unmerchantable woody biomass residues that are often burned in open piles, releasing significant quantities of greenhouse gases and particulates, and potentially damaging the soil beneath the pile. Air curtain burners offer a solution to mitigate these issues, helping to reduce smoke and particulates from burning operations, more fully burn biomass residues compared to pile burning, and eliminate the direct and intense fire contact that can harm soil beneath the slash pile. In an air curtain burner, burning takes place in a controlled environment. Smoke is contained and recirculated by the air curtain, and therefore burning can be conducted under a variety of climatic conditions (e.g.,wind, rain, snow), lengthening the burning season for disposal of slash material. The mobile pyrolysis unit that continuously creates biochar was specifically designed to dispose of residual woody biomass at log landings, green wood at landfills, or salvaged logged materials and create biochar in the process. This high-carbon biochar output can be used to enhance soil resilience by improving its chemical, physical, and biological properties and has potential applications in remediating contaminated soils, including those at abandoned mine sites. Here, we describe the general use of this equipment, appropriate siting, loading methods, quenching requirements, and lessons learned about operating this new technology.

One Health Approach Utilizing Mycelium to Prevent Wildfires in Southeast Ontario

The prevalence and intensity of wildfires have increased dramatically in Ontario, Canada since 2022. This has been exacerbated by climate change, clearcut logging, and poorly extinguished campfires. While previous interventions have targeted the downstream effects of wildfires such as deforestation, there have been no interventions that utilize a One Health approach to equally consider the health of humans, non-human animals, and the environment. This paper proposes a novel and cost-effective initiative utilizing cultivated mycelium from degraded slash piles, harvested and transformed into an organic fire-retardant spray for application on nearby trees. The proposed initiative aims to reduce the risk of wildfire ignition from at-risk trees in Lyndhurst, Ontario to protect the lives of humans and non-human animals as well as the integrity of properties and wildlife habitats, simultaneously contributing to the restoration of forest health as a crucial carbon sink. This may mitigate the effects of climate change and improve air quality, acting as a protective measure for human, non-human animal, and environmental health.

Can Wood Pellets from Canada’s Boreal Forest Reduce Net Greenhouse Gas Emissions from Energy Generation in the UK?

We present the results of a study on the climate forcing effects of replacing coal for power generation in the United Kingdom (UK) with wood pellets produced in northern Ontario, Canada. Continuous wood pellet production from two biomass sources were considered: fiber from increased harvesting of standing live trees (stemwood scenario) and from harvest residue provided by ongoing harvesting operations (residue scenario). In both scenarios, biomass was collected from harvesting operations in two forest management units (FMUs) with contrasting harvest residue treatments: natural decay of slash piles in the Hearst FMU and slash pile burning in the Kenora FMU. Life cycle emissions associated with wood pellets were assessed for production, transportation, and combustion to replace coal at a hypothetical power generating station in the UK. Greenhouse gas (GHG) emissions and removals in wood pellet and coal scenarios were assessed using two methods: global warming potential (GWP)-based mass balance and dynamic life cycle assessment (LCA) approaches. In the stemwood scenario, climate change mitigation from replacing coal with wood pellets was not achieved within the study timeline (2020–2100). In the residue scenario, immediate climate change mitigation was achieved with fiber sourced from the Kenora FMU where the current practice is to burn slash piles; for the Hearst FMU, where slash is allowed to decompose in the forest, climate change mitigation occurred 11.6 and 3.1 years after biomass collection began, as assessed by the mass balance and dynamic LCA methods, respectively. Factors affecting mitigation potential in the studied scenarios are discussed.

Slash-pile burning impacts on the quality of runoff waters in a Mediterranean environment (Croatia)

Slash-pile burning is a frequent land management practice implemented across the Mediterranean. However, the impact of this practice on runoff waters has often been neglected. To address this issue, two experimental burns were conducted: one with moderate (MS) severity, and another with high (HS) severity, to evaluate the impact of different types of slash–pile on the quality of runoff waters. An unburned (UB) treatment was also considered in this study, to evaluate the impacts of slash–pile burning per se. Treatments were established on a slope terrain (∼18°) characteristic of the Adriatic coast. During the two-year study, runoff and erosion samples were collected 22 times after major rainfall events. Aside from runoff, erosion, and total carbon in sediments (TC) were determined, as well as various water quality parameters, including, pH, electrical conductivity (EC), and Br¯, Cl¯, SO42¯, PO43¯, F¯, K+, Na+, Ca2+, and Mg2+. Overall, water quality parameters were more affected shortly after burning, while runoff and erosion were more dependent on precipitation patterns. TC in sediments was higher in HS than in MS, the highest values being observed in the last sampling events for both burned treatments. Regarding runoff water quality, the effects were more pronounced at HS, even if the hydrological response was stronger at the MS. The UB treatment showed significant changes in runoff water quality following major rain events, which was attributed to soil saturation. Our results suggest that slash pile burning has adverse effects on runoff waters, so it is recommended for biomass to be used in other ways, especially in the context of soil and water conservation.

Air quality impact of slash pile burns: Simulated geo-spatial impact assessment for Washington State

In the Western U.S., the prescribed burning of woody biomass in forests, mainly harvest slash, is the prevailing practice for in-woods fuel reduction and wildfire mitigation. Though these prescribed burns play an essential role in mitigating the wildfire risks, the resultant emission is a major air pollutants source that adversely affects air quality, negatively impacting human health. With an increased need for fire hazard reduction thinning, coupled with shrinking regional demand for lower quality biomass (pulpwood, hog-fuel, etc.), the volumes of unused biomass left on the forest floor as ‘waste’ will continue to grow. Reducing prescribed burns by utilizing this ‘waste’ biomass for alternate bio-based solutions (like bio-energy or bio-char) will enhance the economic feasibility of much-needed thinning operations and reduce uncontrolled emissions and related environmental and local health impacts.In this study, we simulate the increase in air pollutants due to additional prescribed fires in the Southwestern part of Washington State. Using the ‘BlueSky smoke modeling system,’ the study estimated the emissions associated with burning additional 726,000 dry t of residual biomass, which corresponds to a 30% increment from 2011. The burn was simulated over 29 days of the fall quarter and subsequently incorporated into the AIRPACT pollution transportation modeling system using the 2011 air quality and meteorological data as the baseline. The results showed that the ambient PM2.5 concentrations, due to the simulated pile burns, exceeded EPA's air quality standards on multiple days and in various locations across the Western part of the state, with two days reaching “very unhealthy” levels and one day reaching “hazardous” levels. By layering the census data on top of the pollution concentration data, the model estimated that, over the 29-day burn period, approximately 440,000 additional human days would be affected by higher than the EPA air-quality standards for ambient PM2.5 levels.

Temporal impacts of pile burning on vegetation regrowth and soil properties in a Mediterranean environment (Croatia)

Burning slash piles is common in the Mediterranean regions to manage the unwanted biomass. This work aims to study the effect of two experimental pile burns ((moderate (MS) and high severity (HS)) conducted in Croatia on vegetation and soil compared to an unburned treatment (UB). We studied vegetation cover (VC), soil water repellency (SWR), mean weight diameter (MWD), water-stable aggregates (WSA), pH, electrical conductivity (EC), soil organic matter (SOM), the total content of calcium (Ca), aluminium (Al), silicon (Si), and iron (Fe), available phosphorus (P2O5) and potassium (K2O). The impacts of the burn were studied 5 days after burning (DAB), 3, 8, 12, and 15 months after burn (MAB). The results showed that VC was significantly higher in UB than in MS 5 DAB-15MAB. SWR was significantly higher in the smallest soil fractions (<0.25 mm) in burn treatments than in the UB on 5 DAB and 3 MAB. Also, 3 MAB, MWD and WSA were significantly lower in the burned treatments than in UB. pH was significantly higher in HS than in UB 3, 12 and 15 MAB, while EC was significantly higher in HS than in UB, 5 DAB, 3 and 15 MAB. MS and HS did not significantly affect SOM content. Total Ca was significantly higher in burn treatments than in UB 5 DAB-12 MAB. Total Al and Si were significantly higher in UB than in HS (5 DAB-15MAB), while total Fe was significantly higher in UB than in HS 5 DAB, and 8–15 MAB. P2O5 was significantly higher in HS than in UB from 3 to 15 MAB, while K2O was significantly higher in MS and HS than in UB 5 DAB. Soils need more time to recover from pile burning disturbance, likely due to the soil poor natural conditions, therefore this type of management is detrimental.

Are soil changes responsible for persistent slash pile burn scars in lodgepole pine forests?

Pile burning is the most common method of logging residue disposal in Rocky Mountain forests. Though the high temperatures reached during burning affect numerous soil properties in the short term, the longer-term effects of the practice are less clear. We previously identified a 50-year time series of burn scars created after clear cut harvesting in lodgepole pine stands where we reported sparse tree colonization across the entire chronosequence. Here we analyzed soil nutrients and chemistry and conducted in situ and greenhouse seedling bioassays to determine whether edaphic factors or poor seedling performance explain the pattern. Pile burning had a lasting effect on soil pH, but nutrient availability was 2–3 times higher in burn scars compared to unburned forest soils for many constituents and planted pine seedlings had good survival and growth. However, seedling growth was slightly less in burn scars compared to unburned soils indicating suboptimal soil pH or other belowground factors may contribute to sparse tree colonization of the openings. For example, seedling survival and ectomycorrhizal fungi colonization were both lowest in the most recently created scars where soils were alkaline and improved with time as pH declined, suggesting gradual amelioration of post-fire growing conditions. Survival in burn scars was comparable for unprotected trees and those in protective mesh tubes, indicating that herbivory was not a significant impediment to seedling establishment. However, a preliminary study suggests that seed predation may have contributed to the low tree colonization into the openings. Though large burn pile scars may require soil rehabilitation, and soil changes may have a lasting effect on understory plant composition, we found that they were not a significant barrier to tree establishment in these moderate-size burn scars.

The challenges of an in situ validation of a nonequilibrium model of soil heat and moisture dynamics during fires

Abstract. With the increasing frequency and severity of fire, there is an increasing desire to better manage fuels and minimize, as much as possible, the impacts of fire on soils and other natural resources. Piling and/or burning slash is one method of managing fuels and reducing the risk and consequences of wildfire, but the repercussions to the soil, although very localized, can be significant and often irreversible. In an effort to provide a tool to better understand the impact of fire on soils, this study outlines the improvements to and the in situ validation of a nonequilibrium model for simulating the coupled interactions and transport of heat, moisture and water vapor during fires. Improvements to the model eliminate the following two important (but heretofore universally overlooked) inconsistencies: one that describes the relationship between evaporation and condensation in the parameterization of the nonequilibrium vapor source term, and the other that is the incorrect use of the apparent thermal conductivity in the soil heat flow equation. The first of these made a small enhancement in the stability and performance of the model. The second is an important improvement in the physics underpinning the model but had less of an impact on the model's performance and stability than the first. This study also (a) develops a general heating function that describes the energy input to the soil surface by the fire and (b) discusses the complexities and difficulties of formulating the upper boundary condition from a surface energy balance approach. The model validation uses (in situ temperature, soil moisture and heat flux) data obtained in a 2004 experimental slash pile burn. Important temperature-dependent corrections to the instruments used for measuring soil heat flux and moisture are also discussed and assessed. Despite any possible ambiguities in the calibration of the sensors or the simplicity of the parameterization of the surface heating function, the difficulties and complexities of formulating the upper boundary condition and the obvious complexities of the dynamic response of the soil's temperature and heat flux, the model produced at least a very credible, if not surprisingly good, simulation of the observed data. This study then continues with a discussion and sensitivity analysis of some important feedbacks (some of which are well known and others that are more hypothetical) that are not included in the present (or any extant) model, but that undoubtedly are dynamically influencing the physical properties of the soil in situ during the fire and, thereby, modulating the behavior of the soil temperature and moisture. This paper concludes with a list of possible future observational and modeling studies and how they would advance the research and findings discussed here.

Wildland fire emission sampling at Fishlake National Forest, Utah using an unmanned aircraft system

Emissions from a stand replacement prescribed burn were sampled using an unmanned aircraft system (UAS, or “drone”) in Fishlake National Forest, Utah, U.S.A. Sixteen flights over three days in June 2019 provided emission factors for a broad range of compounds including carbon monoxide (CO), carbon dioxide (CO2), nitric oxide (NO), nitrogen dioxide (NO2), particulate matter < 2.5 μm in diameter (PM2.5), volatile organic compounds (VOCs) including carbonyls, black carbon, and elemental/organic carbon. To our knowledge, this is the first UAS-based emission sampling for a fire of this magnitude, including both slash pile and crown fires resulting in wildfire-like conditions. The burns consisted of drip torch ignitions as well as ground-mobile and aerial helicopter ignitions of large stands comprising over 1000 ha, allowing for comparison of same-species emission factors burned under different conditions. The use of a UAS for emission sampling minimizes risk to personnel and equipment, allowing flexibility in sampling location and ensuring capture of representative, fresh smoke constituents. PM2.5 emission factors varied 5-fold and, like most pollutants, varied inversely with combustion efficiency resulting in lower emission factors from the slash piles than the crown fires.

A case study of runoff and sediment yield in areas subjected to different forest thinning operations in a northern New Mexico forest

Forest thinning practices play a fundamental role in natural resource management and are used to reduce forest density, particularly in the southwestern United States. Increased forest density can significantly influence fuel loads and subsequent fire severity. Moderate and high fire severity may increase surface runoff and sediment yield during postfire rainfall events. This study was conducted to evaluate the effects of thinning treatments on runoff and sediment yield in northern New Mexico forests. Four cover types were tested to evaluate how they influenced runoff and sedimentation. The four cover types included control (nonthinned), interspace (between slash piles), lop-scatter (slash was scattered and burned), and pile (slash was piled and burned). In addition, each cover type was tested on two categories of slopes: mild slopes (&lt;5%) and moderate slopes (5% to 20%). Rainfall simulations (~16 cm h^–1) for both dry and wet runs were used to measure runoff and sediment yield in 2015 and 2017. Results showed pile treatments had significantly higher time to runoff initiation than did control plots during dry runs. Time to peak runoff was significantly different in mild slope (38.1 min) than moderate slope (25.4 min) in the dry run. Wet run time to peak runoff was found to be greater under the pile treatment as compared to other treatments. Sediment yield was significantly greater on moderate slopes in pile and lop-scatter treatments as compared to control for dry runs. For wet runs, a significant effect was detected between slopes; moderate (greater) slopes produced greater sediment than mild (lesser) slopes. The pile treatments may provide beneficial impacts for watersheds despite the delayed peak runoff in response to rainfall on milder slopes. However, high sediment yield with runoff for pile thinning treatments in steeper slope locations will be important to include when evaluating management impacts on natural resources in the future. Overall, this case study shows that thinning activities in conifer forests of New Mexico have the potential to impact the hydrological function of the watershed and should be considered as part of an overall forest and watershed management strategy.

Ungulate-adapted forestry shows promise for alleviating pine browsing damage

High densities of ungulates can increase human-wildlife conflicts. Where forestry is an important economy, intensive browsing can lead to browsing damage, resulting in volume losses, poor stand regeneration, and reduced timber quality. The forestry industry thus looks for practical, long-term measures to mitigate browsing damage. We tested the effect of two mitigation measures on moose (Alces alces) browsing behaviour and damage to Scots pine (Pinus sylvetris): (1) ungulate-adapted slash piles (i.e., palatable species only) created during felling to increase short-term food availability and (2) intensified soil scarification to increase long-term food availability (collectively, ‘ungulate-adapted forestry’). Our study occurred in southern Norway where we established fixed vegetation and moose faecal pellet plots at varying distances from conventional and ungulate-adapted slash piles and scarified stands. We evaluated the effects of ungulate-adapted slash piles and intensified scarification on the density of undamaged Scots pine, moose bite diameters, browsing pressure, and moose faecal pellet density. To assess the effect of spatial scale, we created 250 m, 500 m, and 1000-m radius buffers centered on each plot. We found that ungulate-adapted logging near our plots increased the density of undamaged pines, as compared to no and conventional logging. We found that logging in general led to smaller bite diameters. We also found that plots near conventional logging had higher browsing pressure, whereas browsing pressure near ungulate-adapted logging was similar to unlogged stands. For scarification, density of undamaged pine increased when the ungulate-adapted stand aged whereas undamaged pine decreased as conventional scarification stands aged. Browsing pressure showed a response at the smallest spatial scale only for ungulate-adapted scarification. Peak moose habitat use near conventional and ungulate-adapted scarified stands differed by stand age and distance from scarification. The overall effects of ungulate-adapted forestry were most pronounced at the smallest spatial scale (250 m). Our results support ‘ungulate-adapted’ forestry as a practical solution to mitigate browsing damage but uncertainty in some of our estimates suggest further research on the area treated is needed.

Direct seeding for restoration of mixed oak forests: Influence of distance to forest edge, predator-derived repellent and acorn size on seed removal by granivorous rodents

Restoration of mixed oak forest in northern temperate regions is important for biodiversity and for adaptation of forest management to climate change. Direct seeding has been considered as a cost-effective method for the assisted regeneration of oaks. However, removal of acorns by granivorous rodents hinders its application. Patterns of acorn removal can vary with habitat type, presence of predators, and acorn size. In this field study, we tested the effects of distance to forest edge, predator excrement as a repellent, and acorn size on the performance of direct-seeded oak in southern Sweden. The experiment was carried out at two different sites. Our hypotheses were: (i) in clear-cuts, acorn removal is higher closer to the forest edge compared to open areas, (ii) treatment with predator excrement reduces acorn removal without affecting germination, and (iii) larger acorns will be removed more readily than smaller acorns. Finally, we also investigated if seedlings from larger acorns survive better and grow taller compared to smaller acorns in relation to habitat structure and predator excrement as repellent. Acorn removal differed at the two sites. At Skrylle (older clear-cut), no forest edge effects were found. At Klåveröd (new clear-cut site), our results suggest that removal of acorns was higher in the open clear-cut due to the presence of large slash piles. Less vegetation coverage correlated with lower rates of acorn removal, except near slash piles. Our results therefore suggest that forest managers should reduce understory vegetation and avoid slash piles during direct seeding of oak. Mink excrement failed to protect acorns against removal, but did not reduce acorn germination. Bigger acorns produced taller seedlings but did not enhance overall woodland establishment due to their higher removal rate. Our results further suggest a potential food satiation effect due to an extra supply of additional food. Satiation manipulation might potentially be a method of mitigating the impact of seed predation by granivorous rodents during the direct seeding of oak, but such an approach requires further research before it could be recommended.

Long-Term Seeding Outcomes in Slash Piles and Skid Trails after Conifer Removal

Conifer removal in interior woodland ecosystems of the western US is a common management treatment used to decrease fire hazard and shift woodlands to more historical states. Woody material is frequently removed by skidding material off site and via slash pile burning. Assessing the long-term outcomes of seeding treatments after such ground disturbing activities is critical for informing future management and treatment strategies. Using two designed experiments from a central Oregon juniper woodland, we resampled slash piles and skid trails 8 years after seeding. Our objectives were to assess the long-term vegetation response to conifer removal, ground disturbance, and seeding source (cultivar and local) in slash piles and skid trails. We found that seeded species persisted in the long term, but abundance patterns depended on the species, seed source, and the type of disturbance. In general, there were more robust patterns of persistence after pile burning compared to skid trails. Seeding also suppressed exotic grass cover in the long term, particularly for the local seed source. However, the invasion levels we report are still problematic and may have impacts on biodiversity, forage and fire behavior. Our short-term results were not predictive of longer-term outcomes, but short- and long-term patterns were somewhat predictable based on species life history traits and ecological succession. The use of a mix of species with different life history traits may contribute to seeding success in terms of exotic grass suppression. Lastly, our results suggest that locally adapted seed sources may perform as well or better compared to cultivars. However, more aggressive weed treatments before and after conifer removal activities and wider seeding application may be needed to effectively treat exotic grass populations.

Slash Pile Burn Scar Restoration: Tradeoffs between Abundance of Non-Native and Native Species

The accumulation of live and dead trees and other vegetation in forests across the western United States is producing larger and more severe wildfires. To decrease wildfire severity and increase forest resilience, foresters regularly remove excess fuel by burning woody material in piles. This common practice could also cause persistent ecosystem changes such as the alteration of soil physical and chemical properties due to extreme soil heating, which can favor invasion by non-native plant species. The abundance and species richness of native plant communities may also remain depressed for many years after burning has removed vegetation and diminished propagules in the soil. This adds to the vulnerability of burned areas to the colonization and dominance by invasive species. Research into the use of revegetation techniques following pile burning to suppress invasion is limited. Studies conducted in various woodland types that investigated revegetation of pile burn scars have met with varying success. To assess the effectiveness of restoring pile burn scars in Rocky Mountain National Park, Colorado, we monitored vegetation in 26 scars, each about 5 m in diameter, the growing season after burning. Later that summer, we selected 14 scars for restoration that included soil scarification, seed addition, and pine duff mulch cover. We monitored the scars for four years, pre-restoration, and three years post-restoration and found that the cover of seeded species exceeded the surrounding unburned areas and unseeded controls. The restoration seeding suppressed cover of non-native species as well as native species that were not seeded during restoration. Our results suggest that restoration of pile burn scars could be a useful tool to retard the establishment of invasive plant species when there are pre-existing infestations near scars. However, this must be weighed against the simultaneous suppression of native species recruitment. Monitoring for periods more than three years will help us understand how long the suppression of native and non-native species by restoration species may persist.

The Influence of Slash Pile Burning on Meadow and Upland Forest Soil Micronutrients in the Sierra Nevada Mountains, United States

Although prescribed fire has been employed as a land management tool for thousands of years, the lasting effect of these events on nutrient cycling, especially the response of micronutrients (elements essential in small amounts for plant growth), is still being explored. This study aimed to quantify the responses of micronutrients to the burning of slash piles within a forested and meadow site in the Sierra Nevada Mountains. At these locations, boron, zinc, and manganese increased following the fire event and ash incorporation, whereas iron decreased and copper had no response. The effects of the fire persisted through at least the following winter season for most nutrients in the forest sites, but the meadow sites appeared to recover from the burn event more rapidly, likely due to differences in the quality of litter as well as the wetter hydrologic regime and chemical properties of the soil type. When applying prescribed fire to ecosystems, care should be taken to limit burn intensity and temperature fluctuations in areas where recovery may occur over longer time scales.

Change in plant species composition on powerline corridor: a case study.

Clear-cutting of powerline corridors (PLCs) adversely affects ecosystem function by fragmenting intact forests and supports biodiversity with the development of a structurally diverse vegetation. The study aimed to determine diversity and composition caused by clear-cutting and monitor change in species composition on the PLC passing through Research Forest of IUC Faculty of Forestry. Species composition was monitored in 10 permanent plots on the clear-cut area (over 3years) paired on the forest edge (over 2years) and forest interior (first year). Diversity, the cover of invasive plants, and life form traits of the sample plots were compared. Change in species composition with time was determined with redundancy analysis (RDA) for repeated measures using CANOCO 5. Open-site conditions caused by clear-cutting promoted the number of hemicryptophyte and therophyte life forms which resulted in a high species richness on the clear-cut area (167 species), followed by forest edge (117 species) and forest interior (60 species). However, species richness which showed a peak in the second year was decreased at the end of 3years. Total cover of invasives was considerably higher on the clear-cut area (23%) compared with the forest (3.78%) and did not make a significant effect on forest interior species in narrow corridors. Clear-cutting combined with slash piling promoted the undesired vertical development of tree sprouts and Robinia pseudoacacia which shortened management rotation in a short period. However, sites dominated by shrubs such as Cistus creticus and Cistus salviifolius suppressed the development and invasion of undesirable trees.

Survival and Predators of Pacific Marten in a Salvage-Logged Pine Forest, South-Central Oregon

Estimating marten (Martes spp.) survival rates in managed forests is important for comparisons with vital rates in unmanaged forests, and data across populations in different forest types are needed in meta-analyses. We estimated survival rates of a Pacific Marten (Martes caurina) population from 1993 to 1998. This population experienced no fur trapping and occurred in an atypical habitat of sparse tree-canopy cover, small tree diameters, and many natural openings and logging clearcuts. In the beetle-damaged, salvage-logged Lodgepole Pine (Pinus contorta) forest, downed wood and snags were removed and slash piles were accumulated to mitigate logging effects. The average annual probability of adult (≥1 y) survival was 0.684, sx = 0.104 (n = 53). The overall adult survival did not differ between years or between the sexes across years. Average annual survival of young (<1 y) was 0.753, sx = 0.118 (n = 26). Seasonal survival of adults (0.945, sx = 0.027) and young (0.974, sx = 0.026) was highest in winter (December through February), and lowest in summer (June through August; adults = 0.853, sx = 0.035; young = 0.902, sx = 0.046). Adult winter survival was significantly greater than summer survival; and for adult females, winter survival was greater than in the other seasons (other seasons range = 0.862 to 0.903) and greater than male winter survival (0.918, sx = 0.039), because there were no known female losses during the period (survival = 1.0). Based on evidence at field recovery sites and laboratory necropsies, predators were associated with 74% of all recovered marten carcasses, including Coyote (Canis latrans), Bobcat (Lynx rufus), American Badger (Taxidea taxus), and raptors of unknown species. Slash piles were used by marten, but the mitigation experiment was discontinued after logging. We suggest that slash piles may have helped sustain the local population of marten in the short term.

Life cycle assessment of residual lignocellulosic biomass-based jet fuel with activated carbon and lignosulfonate as co-products

BackgroundBio-jet fuels are emerging as a valuable alternative to petroleum-based fuels for their potential for reducing greenhouse gas emissions and fossil fuel dependence. In this study, residual woody biomass from slash piles in the U.S. Pacific Northwest is used as a feedstock to produce iso-paraffinic kerosene, through the production of sugar and subsequent patented proprietary fermentation and upgrading. To enhance the economic viability and reduce the environmental impacts of iso-paraffinic kerosene, two co-products, activated carbon and lignosulfonate, are simultaneously produced within the same bio-refinery. A cradle-to-grave life cycle assessment (LCA) is performed for the residual woody biomass-based bio-jet fuel and compared against the cradle-to-grave LCA of petroleum-based jet fuel. This paper also discusses the differences in the environmental impacts of the residual biomass-based bio-jet fuel using two different approaches, mass allocation and system expansion, to partition the impacts between the bio-fuel and the co-products, which are produced in the bio-refinery.ResultsThe environmental assessment of biomass-based bio-jet fuel reveals an improvement along most critical environmental criteria, as compared to its petroleum-based counterpart. However, the results present significant differences in the environmental impact of biomass-based bio-jet fuel, based on the partitioning method adopted. The mass allocation approach shows a greater improvement along most of the environmental criteria, as compared to the system expansion approach. However, independent of the partitioning approach, the results of this study reveal that more than the EISA mandated 60% reduction in the global warming potential could be achieved by substituting petroleum-based jet fuel with residual woody biomass-based jet fuel. Converting residual woody biomass from slash piles into bio-jet fuel presents the additional benefit of avoiding the impacts of slash pile burning in the forest, which results in a net negative impact on ‘Carcinogenics’ and ‘Respiratory effects’, and substantial reduction in the ‘Smog’ and ‘Ecotoxicity’ impacts. The production of woody biomass-based bio-jet fuel, however, did not show any significant improvement in the ‘Acidification’ and ‘Eutrophication’ impact categories.ConclusionsThe study reveals that residual woody biomass recovered from slash piles represents a more sustainable alternative to petroleum for the production of jet fuel with a lower impact on global warming and local pollution. Future research should focus on the optimization of chemical processes of the bio-refinery to reduce the impacts on the ‘Acidification’ and ‘Eutrophication’ impact categories.

Air Quality and Health Impacts of an Aviation Biofuel Supply Chain Using Forest Residue in the Northwestern United States.

Forest residue is a major potential feedstock for second-generation biofuel; however, little knowledge exists about the environmental impacts of the development and production of biofuel from such a feedstock. Using a high-resolution regional air quality model, we estimate the air quality impacts of a forest residue based aviation biofuel supply chain scenario in the Pacific Northwestern United States. Using two potential supply chain regions, we find that biomass and biofuel hauling activities will add <1% of vehicle miles traveled to existing traffic, but the biorefineries will add significant local sources of NO x and CO. In the biofuel production scenario, the regional average increase in the pollutant concentration is small, but 8-hr maximum summer time O3 can increase by 1-2 ppb and 24-hr average maximum PM2.5 by 2 μg/m3. The alternate scenario of slash pile burning increased the multiday average PM2.5 by 2-5 μg/m3 during a winter simulation. Using BenMAP, a health impact assessment tool, we show that avoiding slash pile burning results in a decrease in premature mortality as well as several other nonfatal and minor health effects. In general, we show that most air quality and health benefits result primarily from avoided slash pile burning emissions.