Fire Ecology & Effects
Webinar recording.
Over the last 30 years, in woodland and forested ecosystems across the southwestern US, there has been an increasing trend in fire activity. Altered land use practices and more recent changes in precipitation patterns and warmer temperatures are widely thought to contribute to departures in fire regimes toward more frequent and larger fires with more extreme fire behavior that threatens the persistence of the various forested ecosystems. We examined climate-fire relationships in these vegetation types in Arizona and New Mexico using an expanded satellite-derived burn severity dataset that incorporates over one million additional burned hectares analyzed as extended assessments to the MTBS project’s data and five climate variables from PRISM. Climate-fire relationships were identified by comparing annual total area burned, area burned at high/low severity, and percent high severity regionally with fire season (May-August) and water year (October-September) temperature, precipitation, and vapor pressure deficit (VPD) variables. The high severity indicators were also derived for each fire individually to see if climate-fire relationships persist at the scale of the individual fire. Increasing trends toward more arid conditions were observed in all but two of the climate variables. Furthermore, VPD-fire correlations were consistently as strong or more correlated compared to temperature or precipitation indicators alone, both regionally and at the scale of the individual fire. Thus, our results support the use of VPD as a more comprehensive climate metric than temperature or other water-balance measures to predict future fire activity. Managers will have to face the implications of increasing high severity fire as trends in climate toward warmer and drier conditions become an increasingly dominant factor in driving fire regimes towards longer and more intense fire seasons across the Southwest.
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Many studies have examined how fuels, topography, climate, and fire weather influence fire severity. Less is known about how different forest management practices influence fire severity in multi‐owner landscapes, despite costly and controversial suppression of wildfires that do not acknowledge ownership boundaries. In 2013, the Douglas Complex burned over 19,000 ha of Oregon & California Railroad (O&C) lands in Southwestern Oregon, USA. O&C lands are composed of a checkerboard of private industrial and federal forestland (Bureau of Land Management, BLM) with contrasting management objectives, providing a unique experimental landscape to understand how different management practices influence wildfire severity. Leveraging Landsat based estimates of fire severity (Relative differenced Normalized Burn Ratio, RdNBR) and geospatial data on fire progression, weather, topography, pre‐fire forest conditions, and land ownership, we asked (1) what is the relative importance of different variables driving fire severity, and (2) is intensive plantation forestry associated with higher fire severity?
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In ponderosa pine (Pinus ponderosa) forests of the western United States, prescribed burns are used to reduce fuel loads and restore historical fire regimes. The season of and interval between burns can have complex consequences for the ecosystem, including the production of pyrogenic carbon (PyC). PyC plays a crucial role in soil carbon cycling, displaying turnover times that are orders of magnitude longer than unburned organic matter. This work investigated how the season of and interval between prescribed burns affects soil organic matter, including the formation and retention of PyC, in a ponderosa pine forest of eastern Oregon.
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Scientists at the Southern Research Stations of the US Forest Service combined the hydrometeorological and fire data for 168 fire-affected areas in the contiguous United States collected between 1984 and 2013. This enabled them to determine when wildland fires can affect the annual amount of flow in rivers, and to create a suite of climate and wildland fire impact models adapted to local conditions.
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Today many forested landscapes in western states have a “fire debt.” Humans have prevented normal levels of fire from occurring, and the bill has come due. Increasingly severe weather conditions and longer fire seasons due to climate change are making fire management problems more pressing today than they were just a few decades ago. And the problem will only get worse.
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Although we detected shifts in the relative abundance of several bee and plant genera along the fire severity gradient, the two most abundant bee genera (Bombus and Halictus) responded positively to high fire severity despite differences in their typical foraging ranges. Our study demonstrates that within a large wildfire mosaic, severely burned forest contained the most diverse wild bee communities. This finding has particularly important implications for biodiversity in fire-prone areas given the expected expansion of wildfires in the coming decades.
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Taken together, findings suggest that the response of stream chemistry to wildfires in the Sierra Nevada, California, can persist for years, varying with both fire severity and site-specific characteristics. These impacts may have important implications for biogeochemical cycles and productivity in aquatic ecosystems in fire-adapted landscapes.
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Strategically placed landscape area fuel treatments in the Sierra Nevada were put to the test in this study when the American Fire burned through previously treated areas. Both fire effects and initial post-fire conifer regeneration were investigated.
The following links are recordings of the presentations made by Working Lands for Wildlife researchers at The Wildlife Society’s 26th Annual Conference. This conference was in Reno, Nevada in October 2019. These videos are courtesy of The Wildlife Society and the USDA-NRCS Working Lands for Wildlife and Conservation Effect Assessment Project.
Cut a tree, grow a grouse: Implications of juniper removal for sage-grouse population growth
Sage-grouse: Microhabitat specialist or sagebrush generalist
Revolutionizing rangeland monitoring
Part 1 recordings.
Part 2 recordings.
Gambel oak (Quercus gambelii) is a widespread species found throughout the US Southwest and southern Rocky Mountains. While the species has been widely studied in Arizona and New Mexico, comparatively little is known about Gambel oak at the northern extent of its range (Colorado, Utah, southern Wyoming). Research in this geographic region is particularly important given substantial differences in growth form across the species’ range (tree vs. shrub), and because potential habitat for Gambel oak is likely to spread northward under future climate scenarios. In this webinar, we will discuss the current state of knowledge on the ecology and management of Gambel oak in the southern Rocky Mountains, with a focus on silviculture, wildfire, and post-fire.