Research Database
Displaying 21 - 40 of 46
The influence of fire history on soil nutrients and vegetation cover in mixed-severity fire regime forests of the eastern Olympic Peninsula, Washington, USA
Year: 2018
The rain shadow forests of the Olympic Peninsula exemplify a mixed-severity fire regime class in the midst of a highly productive landscape where spatial heterogeneity of fire severity may have significant implications for below and aboveground post-fire recovery. The purpose of this study was to quantify the impacts of wildfire on forest soil carbon (C) and nitrogen (N) pools and assess the relationship of pyrogenic carbon (PyC) to soil processes in this mixed-severity ecosystem. We established a 112-year fire chronosequence with nine similar forest stands ranging in time since lastfire (TSF…
Publication Type: Journal Article
Cumulative effects of wildfires on forest dynamics in the eastern Cascade Mountains, USA
Year: 2018
Wildfires pose a unique challenge to conservation in fire‐prone regions, yet few studies quantify the cumulative effects of wildfires on forest dynamics (i.e., changes in structural conditions) across landscape and regional scales. We assessed the contribution of wildfire to forest dynamics in the eastern Cascade Mountains, USA from 1985 to 2010 using imputed maps of forest structure (i.e., tree size and canopy cover) and remotely sensed burn severity maps. We addressed three questions: (1) How do dynamics differ between the region as a whole and the unburned portion of the region? (2) How do…
Publication Type: Journal Article
Climate changes and wildfire alter vegetation of Yellowstone National Park, but forest cover persists
Year: 2017
We present landscape simulation results contrasting effects of changing climates on forest vegetation and fire regimes in Yellowstone National Park, USA, by mid-21st century. We simulated potential changes to fire dynamics and forest characteristics under three future climate projections representing a range of potential future conditions using the FireBGCv2 model. Under the future climate scenarios with moderate warming (>2°C) and moderate increases in precipitation (3–5%), model simulations resulted in 1.2–4.2 times more burned area, decreases in forest cover (10–44%), and reductions in…
Publication Type: Journal Article
Emissions from prescribed burning of timber slash piles in Oregon
Year: 2017
Emissions from burning piles of post-harvest timber slash (Douglas-fir) in Grande Ronde, Oregon were sampled using an instrument platform lofted into the plume using a tether-controlled aerostat or balloon. Emissions of carbon monoxide, carbon dioxide, methane, particulate matter (PM2.5), black carbon, ultraviolet absorbing PM, elemental/organic carbon, filter-based metals, polycyclic aromatic hydrocarbons (PAHs), polychlorinated dibenzodioxins/dibenzofurans (PCDD/PCDF), and volatile organic compounds (VOCs) were sampled to determine emission factors, the amount of pollutant formed per amount…
Publication Type: Journal Article
Restoring forest structure and process stabilizes forest carbon in wildfire-prone southwestern ponderosa pine forests
Year: 2016
Changing climate and a legacy of fire-exclusion have increased the probability of high-severity wildfire, leading to an increased risk of forest carbon loss in ponderosa pine forests in the southwestern USA. Efforts to reduce high-severity fire risk through forest thinning and prescribed burning require both the removal and emission of carbon from these forests, and any potential carbon benefits from treatment may depend on the occurrence of wildfire. We sought to determine how forest treatments alter the effects of stochastic wildfire events on the forest carbon balance. We modeled three…
Publication Type: Journal Article
Burning the legacy? Influence of wildfire reburn on dead wood dynamics in a temperate conifer forest
Year: 2016
Dynamics of dead wood, a key component of forest structure, are not well described for mixed- severity fi re regimes with widely varying fi re intervals. A prominent form of such variation is when two stand- replacing fi res occur in rapid succession, commonly termed an early- seral “reburn.” These events are thought to strongly infl uence dead wood abundance in a regenerating forest, but this hypothesis has scarcely been tested. We measured dead wood following two overlapping wildfi res in coniferdominated forests of the Klamath Mountains, Oregon (USA), to assess whether reburning (15- yr…
Publication Type: Journal Article
Forest management scenarios in a changing climate: trade-offs between carbon, timber, and old forest
Year: 2016
Balancing economic, ecological, and social values has long been a challenge in the forests of the Pacific Northwest, where conflict over timber harvest and old-growth habitat on public lands has been contentious for the past several decades. The Northwest Forest Plan, adopted two decades ago to guide management on federal lands, is currently being revised as the region searches for a balance between sustainable timber yields and habitat for sensitive species. In addition, climate change imposes a high degree of uncertainty on future forest productivity, sustainability of timber harvest,…
Publication Type: Journal Article
Effects of harvest, fire, and pest/pathogen disturbances on the West Cascades ecoregion carbon balance
Year: 2015
Disturbance is a key influence on forest carbon dynamics, but the complexity of spatial and temporal patterns in forest disturbance makes it difficult to quantify their impacts on carbon flux over broad spatial domains.Here we used a time series of Landsat remote sensing images and a climate-driven carbon cycle process model to evaluate carbon fluxes at the ecoregion scale in western Oregon.
Publication Type: Journal Article
Wildland fire emissions, carbon, and climate: Modeling fuel consumption
Year: 2014
Fuel consumption specifies the amount of vegetative biomass consumed during wildland fire. It is a two-stage process of pyrolysis and combustion that occurs simultaneously and at different rates depending on the characteristics and condition of the fuel, weather, topography, and in the case of prescribed fire, ignition rate and pattern. Fuel consumption is the basic process that leads to heat absorbing emissions called greenhouse gas and other aerosol emissions that can impact atmospheric and ecosystem processes, carbon stocks, and land surface reflectance. It is a critical requirement for…
Publication Type: Journal Article
Mapping the daily progression of large wildland fires using MODIS active fire data
Year: 2014
High temporal resolution information on burnt area is needed to improve fire behaviour and emissions models. We used the Moderate Resolution Imaging Spectroradiometer (MODIS) thermal anomaly and active fire product (MO(Y)D14) as input to a kriging interpolation to derive continuous maps of the timing of burnt area for 16 large wildland fires. For each fire, parameters for the kriging model were defined using variogram analysis. The optimal number of observations used to estimate a pixel’s time of burning varied between four and six among the fires studied. The median standard error from…
Publication Type: Journal Article
The relationship of post-fire white ash cover to surface fuel consumption
Year: 2013
White ash results from the complete combustion of surface fuels, making it a logically simple retrospective indicator of surface fuel consumption. However, the strength of this relationship has been neither tested nor adequately demonstrated with field measurements. We measured surface fuel loads and cover fractions of white ash and four other surface materials (green vegetation, brown non-photosynthetic vegetation, black char and mineral soil) immediately before and after eight prescribed fires in four disparate fuelbed types: boreal forest floor, mixed conifer woody slash, mixed conifer…
Publication Type: Journal Article
Do carbon offsets work? The role of forest management in greenhouse gas mitigation
Year: 2013
Publication Type: Report
Does Wood Bioenergy Increase Carbon Stocks in Forests?
Year: 2012
Wood bioenergy is touted as carbon neutral because biological regrowth recaptures the carbon released in energy production. However, some argue that using wood as an energy feedstock will result in decreased forest stocks and thereby a net reduction of carbon sequestered by forests. Such arguments fail to recognize that increased demand for wood bioenergy could increase stocks of wood, a renewable resource. We address the carbon neutrality question using a dynamic optimization forest management model to examine the effect of increasing or decreasing wood bioenergy demand on an existing forest…
Publication Type: Journal Article
Effects of Ungulate Herbivory on Aspen, Cottonwood, and Willow Development Under Forest Fuels Treatment Regimes
Year: 2012
Herbivory by domestic and wild ungulates can dramatically affect vegetation structure, composition and dynamics in nearly every terrestrial ecosystem of the world. These effects are of particular concern in forests of western North America, where intensive herbivory by native and domestic ungulates has the potential to substantially reduce or eliminate deciduous, highly palatable species of aspen (Populus tremuloides), cottonwood (Populus trichocarpa), and willow (Salix spp.). In turn, differential herbivory pressure may favor greater establishment of unpalatable conifers that serve as ladder…
Publication Type: Journal Article
Forest Protection and Forest Harvest as Strategies for Ecological Sustainability and Climate Change Mitigation
Year: 2012
An important consideration in forest management to mitigate climate change is the balance between forest carbon (C) storage and ecological sustainability. We explore the effects of management strategies on tradeoffs between forest C stocks and ecological sustainability under five scenarios, three of which included management and two scenarios which provide baselines emulating the natural forest. Managed forest scenarios were: (a) Protection (PROT), i.e., management by suppression of natural disturbance and harvest exclusion; (b) Harvest at a higher rate removing all sustainably available wood…
Publication Type: Journal Article
Timing of carbon emissions from global forest clearance
Year: 2012
Land-use change, primarily from conventional agricultural expansion and deforestation, contributes to approximately 17% of global greenhouse-gas emissions. The fate of cleared wood and subsequent carbon storage as wood products, however, has not been consistently estimated, and is largely ignored or oversimplified by most models estimating greenhouse-gas emissions from global land-use conversion. Here, we estimate the fate of cleared wood and timing of atmospheric carbon emissions for 169 countries. We show that 30 years after forest clearance the percentage of carbon stored in wood products…
Publication Type: Journal Article
Fuel treatment impacts on estimated wildfire carbon loss from forests in Montana, Oregon, California, and Arizona
Year: 2012
Using forests to sequester carbon in response to anthropogenically induced climate change is being considered across the globe. A recent U.S. executive order mandated that all federal agencies account for sequestration and emissions of greenhouse gases, highlighting the importance of understanding how forest carbon stocks are influenced by wildfire. This paper reports the effects of the most common forest fuel reduction treatments on carbon pools composed of live and dead biomass as well as potential wildfire emissions from six different sites in four western U.S. states. Additionally, we…
Publication Type: Journal Article
Carbon Outcomes from Fuels Treatment and Bioenergy Production in a Sierra Nevada Forest
Year: 2012
In temperate conifer forests of the Western USA, there is active debate whether fuels reduction treatments and bioenergy production result in decreased carbon emissions and increased carbon sequestration compared to a no-action alternative. To address this debate over net carbon stocks, we performed a carbon life-cycle analysis on data from a fuels reduction treatment in a temperate, dry conifer forest in the northern Sierra Nevada of California, USA. The analysis tracks the net ecosystem carbon balance over 50 years for two scenarios (1) fuels reduction treatment combined with bioenergy…
Publication Type: Journal Article
Estimating Consumption and Remaining Carbon in Burned Slash Piles
Year: 2012
Fuel reduction treatments to reduce fire risk have become commonplace in the fire adapted forests of western North America. These treatments generate significant woody debris, or slash, and burning this material in piles is a common and inexpensive approach to reducing fuel loads. Although slash pile burning is a common practice, there is little information on consumption or even a common methodology for estimating consumption. As considerations of carbon storage and emissions from forests increase, better means of quantifying burn piles are necessary. This study uses two methods, sector…
Publication Type: Journal Article
Arbuscular Mycorrhizal Fungi Increase Organic Carbon Decomposition Under Elevated CO2
Year: 2012
The extent to which terrestrial ecosystems can sequester carbon to mitigate climate change is a matter of debate. The stimulation of arbuscular mycorrhizal fungi (AMF) by elevated atmospheric carbon dioxide (CO 2 ) has been assumed to be a major mechanism facilitating soil carbon sequestration by increasing carbon inputs to soil and by protecting organic carbon from decomposition via aggregation. We present evidence from four independent microcosm and field experiments demonstrating that CO 2 enhancement of AMF results in considerable soil carbon losses. Our findings challenge the assumption…
Publication Type: Journal Article