Fire Regimes

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What’s new in LANDFIRE: Remap

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This webinar seeks to inform participants about what to expect from LANDFIRE Remap products, and what has and has not changed from previous product offerings. We will discuss what we have learned since February 2019 when the products were made available to users in the Northwest, and how LANDFIRE resources can address specific fire and land management issues.

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Distinguishing disturbance from perturbations in fire-prone ecosystems

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Here, we provide a brief overview of examples where anthropogenically driven changes in fire frequency, fire pattern, fuels consumed and fire intensity constitute perturbations that greatly disrupt natural disturbance cycles and put ecosystems on a different trajectory resulting in type conversion. These changes are not due to fire per se but rather anthropogenic perturbations in the natural disturbance regime.

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Mountain big sagebrush – Fire regimes

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Estimates of historical fire regime parameters in mountain big sagebrush communities can be compared with current fire regimes and trends to establish general guidelines for ecological restoration. A synthesis of information on historical patterns and contemporary changes in fuels and fire regimes in mountain big sagebrush communities is available in the Fire Effects Information System (FEIS). This research brief summarizes information from that FEIS Fire Regime Synthesis.

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Wildfires, invasive grass threaten future of western sagebrush

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Humans are the source of 84 percent of wildfires, and not all are intentional. Often they come from vehicle accidents in dry landscapes. In fact, over the last 20 years, 11 of the 50 largest wildfires in the U.S. have occurred in the Great Basin. From 2000 to 2018, approximately 15 million acres of sagebrush burned primarily in the Great Basin, and approximately 9 million of those acres burned from 2014 to 2018 alone, said Michele Crist, a landscape ecologist with the Bureau of Land Management at the National Interagency Fire Center in Boise, Idaho.

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Unraveling the complexity of mixed severity fire regimes: New insights from three Rocky Mountain ecosystems

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In this webinar, Dr. Cameron Naficy presents findings from a synthesis of multiple projects conducted in 3 unique mixed-severity ecosystems from the Rocky Mountains of the U.S. and Canada. He briefly reviews a new reconstruction method his research group developed that combines extensive dendroecological plot networks and detailed forest structure mapping from high-resolution historical aerial imagery. Using these data, he describes the spatial and temporal patterns of fire frequency and severity for each study ecosystem, the fire-mediated stand dynamics and vegetation conditions that characterized each ecosystem, and some novel resilience mechanisms and ecological surprises associated with the mixed-severity fire regime model. This project demonstrates how historical data can be used to move beyond simple summaries of historical fire regime attributes and landscape condition by using historical data to reveal fundamental fire regime processes, drivers, and ecological outcomes.

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Consequences of climatic thresholds for projecting fire activity and ecological change

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These results highlight a high sensitivity of statistical projections to changing threshold relationships and data uncertainty, implying that projections of future ecosystem change in threshold‐governed ecosystems will be accompanied by notable uncertainty. This work also suggests that ecological responses to climate change will exhibit high spatio‐temporal variability as different regions approach and surpass climatic thresholds over the 21st century.

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Shifting global fire regimes: Lessons from reburns and research needs

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This study reviews published studies on reburns in fire-adapted ecosystems of the world, including temperate forests of North America, semi-arid forests and rangelands, tropical and subtropical forests, grasslands and savannas, and Mediterranean ecosystems. To date, research on reburns is unevenly distributed across the world with a relative abundance of literature in Australia, Europe and North America and a scarcity of studies in Africa, Asia and South America. This review highlights the complex role of repeated fires in modifying vegetation and fuels, and patterns of subsequent wildfires. In fire-prone ecosystems, the return of fire is inevitable, and legacies of past fires, or their absence, often dictate the characteristics of subsequent fires.

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Common ground regarding the role of wildfire in forested landscapes of the western US

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A group of people knowledgeable about wildland fire have produced a 52-page document that attempts to assemble and summarize areas of agreement and disagreement regarding the management of forested areas in the western United States. Calling themselves the Fire Research Consensus Working Group, they looked for areas of common ground to provide insights for scientists and land managers with respect to recent controversies over the role of low-, moderate-, and high-severity fires.

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Fire regimes of mountain big sagebrush communities – Review from FEIS

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This synthesis summarizes information available in the scientific literature on historical patterns and contemporary changes in fuels and fire regimes in mountain big sagebrush communities. This literature suggests that presettlement fires in the sagebrush biome were both lightning- and human-caused. Peak fire season occurred between April and October and varied geographically. Wildfires were high-severity, stand-replacement fires. Fire frequency estimates range from decades to centuries, depending on the applicable scale, methods used, and metrics calculated. Fire frequency was influenced by site characteristics. Because mountain big sagebrush communities occur over a productivity gradient driven by soil moisture and temperature regimes, fire regimes likely varied across the gradient, with more frequent fire on more productive sites that supported more continuous fine fuels. Sites dominated by mountain big sagebrush burned more frequently than sites dominated by Wyoming big sagebrush, because the former tend to be more productive. Mountain big sagebrush communities adjacent to fire-prone forest types (e.g., ponderosa pine) may have had more frequent fires than those adjacent to less fire-prone types (e.g., pinyon-juniper) and those far from forests and woodlands. Most fires were likely small (less than ~1,200 acres (~500 ha)), and large fires (>24,000 acres (10,000 ha)) were infrequent. Historically, large fires in big sagebrush were most likely after one or more relatively wet years or fire reseasons that favored growth of associated grasses, allowing fine fuels to accumulate and become more continuous.

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Do post-fire fuel treatments and annual grasses interact to affect fire regimes in the Great Basin?

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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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