Synthesis / Tech Report
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To assess the effects of aerial and drill seeding on plant community trajectories, fuel composition, and fire regimes, this study collected geospatial datasets spanning 209,000 ha of sagebrush steppe on BLM land in southern Idaho. In the field, 68 sites were sampled for fuel and plant community composition in 2014 and 2015 across areas that had burned 1-6 times and had no, aerial, drill, or aerial + drill seeding. The study found that 1) fire and rehabilitation shaped plant communities, 2) drill seeding after multiple fires in dry, low elevation sites prevented conversion to cheatgrass-dominated systems, 3) drill seeded sites had fewer fires and increased in fire frequency more slowly than aerial seeded sites, 4) the on-the-ground conditions that led to the decision to aerially seeding after a fire led to more frequent and numerous fires.
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Using epidemiology studies to understand the exposure-response relationship for PM, this study found that firefighters were at an increased risk for long-term health effects from smoke exposure. The risk for lung cancer mortality increases nearly linearly with exposures over time and is more strongly influenced by exposure duration than are the risks of death from cardiovascular or ischemic heart disease. On the other hand, the risk of cardiovascular mortality rises steeply for doses in the range we estimated for firefighter exposures but flattens out at higher exposures to PM. The data presented in this paper clearly identify the crews and activities most likely to exceed occupational exposure limits and firefighters may have a an increased health risk from smoke exposures.
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Mixed severity wildfires burn large areas in western North America forest ecosystems in most years and this is expected to continue or increase with climate change. Little is understood about vegetation recovery and changing fuel conditions more than a decade post-fire because it exceeds the duration of most studies of fire effects. We measured plant species composition, conifer seedling regeneration, fuel loads, and ground cover at 15 wildfires that burned 9-15 years previous in five western U.S. vegetation types distributed across eight states including Alaska.
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This report contains descriptions of USGS sage-grouse and sagebrush ecosystem research projects that are ongoing or were active during 2018 and is organized into five thematic areas: Fire, Invasive Species, Restoration, Sagebrush, Sage-Grouse, and Other Sagebrush-Associated Species; and Climate and Weather.
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Data on plant cover and density was collected on 67 sites in a 209,000 ha study area that varied in fire and post-fire rehabilitation history along gradients in elevation, soil texture, and precipitation. Multiple linear regression indicated significant inverse relationships between B. tectorum and both P. secunda and A. cristatum, but P. secunda had suppressed B. tectorum cover and density better than A. cristatum. A nonparametric multiple regression analyzing the effect of 86 abiotic and biotic independent variables indicated that elevation, mid to late season native perennial bunchgrasses, and the number of post-fire rehabilitation treatments (for B. tectorum cover) or time since most recent rehabilitation (for B. tectorum density) explained the most variation in Bromus tectorum suppression across the landscape.
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This Rangelands on the Edge (ROTE) project improves our understanding of the fate of rangelands from historical, present day, and future perspectives by describing human modification, fragmentation, and future residential growth projections for rangeland-dominated vegetation. Since pre-European settlement, some 340 million acres (over 34 percent) of rangelands, particularly in the Great Plains, have been converted to alternative land uses, especially intensive agriculture (croplands, pastureland). Approximately 11 percent of private rangelands are likely to experience significant increases in housing development over the next 15 years.
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This report presents a new fuel sampling method, called the photoload sampling technique, to quickly and accurately estimate loadings for six common surface fuel components (1 hr, 10 hr, 100 hr, and 1000 hr downed dead woody, shrub, and herbaceous fuels). This technique involves visually comparing fuel conditions in the field with photoload sequences to estimate fuel loadings. Photoload sequences are a series of downward-looking and close-up oblique photographs depicting a sequence of graduated fuel loadings of synthetic fuelbeds for each of the six fuel components.
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The original objective of the study was to determine how ignition, smoldering, and flaming are affected by the age of masticated fuels using a combined field and lab approach.
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Almost half of the full community costs of wildfire are paid for at the local level, including homeowners, businesses, and government agencies. Many of these costs are due to long-term damages to community and environmental services, such as landscape rehabilitation, lost business and tax revenues, and property and infrastructure repairs. By comparison, our analysis suggests suppression costs comprise around nine percent of total wildfire costs. The remaining costs include short-term expenses, or those costs occurring within the first six months—and long-term damages accruing during many months and years following a wildfire. Communities at risk to wildfires can reduce wildfire impacts and associated costs through land use planning.
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This report is an outstanding complete description of not only the Rothermel model, but also the modifications and addendums that have evolved for supporting the many systems that use the model. This work shows all the equations, discusses their relevance, and illustrates graphically their response to changes in their inherent variables. The variables required for driving the models referred to as inputs, which must be obtained to describe the environment in which the fire is burning, are often misunderstood.