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Figure J2. Seven floristic provinces used in recently published studies that analyzed fire patterns and trends in the sagebrush (Artemisia spp.) biome, particularly by focusing on ecosystem types or biophysical settings capable of supporting sagebrush as dominant species.
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Crist, M.R., Belger, R., Davies, K.W., Davis, D.M., Meldrum, J.R., Shinneman, D.J., and Mayer, K.E. 2021. Chapter J. Altered Fire Regimes. Pages 79-98 in: Remington, T.E., Deibert, P.A., Hanser, S.E., Davis, D.M., Robb, L.A., and Welty, J.L., Sagebrush conservation strategy—Challenges to sagebrush conservation: U.S. Geological Survey Open-File Repo...
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... addition, detection of ecoregional trends in area burned has also varied among studies. Miller and others (2011) found a weak but significant upward trend in area burned in four of five floristic provinces (Northern Great Basin, Southern Great Basin, Silver Sagebrush, and Wyoming Basin; fig. J2). Baker (2013) found significant trends in only two of seven provinces (Colorado Plateau and Columbia Basin) by using different methods, although three others (Silver Sagebrush, Snake River Plains, and Southern Great Basin) were nearly significant. In another study ( Brooks and others, 2015), there was strong evidence of increased fire ...Similar publications
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... Across all fire-history studies relevant to sagebrush ecosystems, most have generally concluded that fire area (i.e., area burned) over the past approximately 30 yr has increased in some regions (as reviewed by Crist et al. 2021 ). However, there is mixed agreement regarding landscape trends in area burned owing to different spatial and temporal extents, ecosystem delineations, statistical approaches, and datasets used. ...
Fire regimes in sagebrush (Artemisia spp.) ecosystems have been greatly altered across the western United States. Broad-scale invasion of non-native annual grasses, climate change, and human activities have accelerated wildfire cycles, increased fire size and severity, and lengthened fire seasons in many sagebrush ecosystems to the point that current wildfire-management practices and postfire restoration efforts cannot keep pace to ameliorate the ecological consequences of sagebrush ecosystem loss. The greatest impact of uncharacteristically frequent fire is the transition from native sagebrush-perennial grass communities to invasive, non-native, annual grasslands that are highly flammable. These community transitions are often permanent, owing to the low probability of reestablishing native perennial plants in non-native annual grass−dominated communities. Moreover, these grasses can form extensive and continuous fine fuel loads that promote more frequent fire and the continued expansion of invasive, non-native annuals. More frequent, larger, and severe wildfires necessitate greater resources for fire-prevention, fire-suppression, and postfire restoration activities, while decreasing critical ecosystem services, economic and recreational opportunities, and cultural traditions. Increased flexibility and better prioritization of management activities based on ecological needs, including commitment to long-term prefire and postfire management, are needed to achieve notable reductions in uncharacteristic wildfire activity and associated negative impacts. Collaboration and partnerships across jurisdictional boundaries, agencies, and disciplines can improve consistency in sagebrush-management approaches and thereby contribute to this effort. Here, we provide a synthesis on sagebrush wildfire trends and the impacts of uncharacteristic fire regimes on sagebrush plant communities, dependent wildlife species, fire-suppression costs, and ecosystem services. We also provide an overview of wildland fire coordination efforts among federal, state, and tribal entities.
... Inset map shows the location of the top 10 MLRAs; use MLRA number for reference during a recent 30-year period. Crist et al. (2021) reported that most areas with recurrent fire in sagebrush ecosystems burned twice (71%) resulting in an average fire return interval of 15 years for those areas. They found that the remaining 29% of areas with recurrent fire burned three or more times for an average fire return interval of 7.5 years or less. ...
The U.S. federal government has recently committed to the difficult task of slowing and managing the invasive grass‐fire cycle in sagebrush steppe, where property, livelihoods, and entire ecosystems are at risk. To safely manage this crisis, the government recently proposed to construct about 17,700 km of fuel breaks and millions of hectares of fuel reduction treatments in six western states. A challenge for resource managers will be the strategic placement of these land treatments. We investigated the need for this massive effort from the perspective of protecting previous rehabilitation and restoration seeding investments, including over 3,400 seedings implemented from 1990 to 2019 covering about 24,540 km2. We found that portions of over 26% of these seedings have since burned representing nearly 17% of this seeded area. Locations that had recurrent wildfire had repeat treatments and thus multiple investments in the same location. Our analysis supports the management actions aimed at protecting remaining sagebrush and restoration investments, especially in areas where the invasive grass‐fire cycle is most pervasive. Given the decades required for most sagebrush to recover after wildfire, the urgency of this management intervention is evident. The specific details, placement, and effectiveness of these interventions could influence outcomes and potential unintended consequences. We investigated the need for a massive fuel break network in parts of the Great Basin from the perspective of protecting previous rehabilitation and restoration seeding investments implemented from 1990 to 2019. We found that portions of over 26% of these seedings have since burned representing nearly 17% of this seeded area. Our analysis contributes to a growing body of evidence that support proposed management actions aimed at protecting remaining sagebrush and restoration investments, especially in areas where the invasive grass‐fire cycle is most pervasive.
... Sage-grouse populations at the periphery of their range where habitat suitability is already marginal are likely to be lost due to declines in big sagebrush, hotter and more persistent droughts due to warming (Adler et al., 2021), and expansion of invasive annual grasses and increased fire risk (Boyd et al., 2021;Crist et al., 2021). This is corroborated by Aldridge et al. (2008), who documented extirpation of greater sage-grouse in lower latitude, warm, dry sites in response to drought. ...
Plant community response to climate change will be influenced by individual plant responses that emerge from competition for limiting resources that fluctuate through time and vary across space. Projecting these responses requires an approach that integrates environmental conditions and species interactions that result from future climatic variability. Dryland plant communities are being substantially affected by climate change because their structure and function are closely tied to precipitation and temperature, yet impacts vary substantially due to environmental heterogeneity, especially in topographically complex regions. Here, we quantified the effects of climate change on big sagebrush (Artemisia tridentata Nutt.) plant communities that span 76 million ha in the western United States. We used an individual‐based plant simulation model that represents intra‐ and inter‐specific competition for water availability, which is represented by a process‐based soil water balance model. For dominant plant functional types, we quantified changes in biomass and characterized agreement among 52 future climate scenarios. We then used a multivariate matching algorithm to generate fine‐scale interpolated surfaces of functional type biomass for our study area. Results suggest geographically divergent responses of big sagebrush to climate change (changes in biomass of ‐20% to +27%), declines in perennial C3 grass and perennial forb biomass in most sites, and widespread, consistent, and sometimes large increases in perennial C4 grasses. The largest declines in big sagebrush, perennial C3 grass and perennial forb biomass were simulated in warm, dry sites. In contrast, we simulated no change or increases in functional type biomass in cold, moist sites. There was high agreement among climate scenarios on climate change impacts to functional type biomass, except for big sagebrush. Collectively, these results suggest divergent responses to warming in moisture‐limited vs. temperature‐limited sites and potential shifts in the relative importance of some of the dominant functional types that result from competition for limiting resources.
Spatial and temporal dynamics of rangeland fuels is a primary factor driving large wildfires. Yet detailed information capturing variation in fine fuels has largely been missing from rangeland fire planning and fuels management. New fuels-based maps of Great Basin rangeland fire probability help bridge this gap by coupling dynamic vegetation cover and production data from the Rangeland Analysis Platform with weather and climate data to provide annual forecasts of the relative probability of large wildfire. In this paper, we review these new fuels-based maps and discuss implications for prefire planning, preparedness, and strategic fuels management. Examining patterns of fire probability through time reveals high spatial and temporal variation in risk of large wildfires across the Great Basin. Certain areas are chronically impacted with high fire probability most years, while others have more sporadic or low probability of large fire annually. Maps confirm previous research that the recent increase in large fire risk in the region is highly associated with invasive annual grasses, but total aboveground herbaceous production (including perennials) continues to be a primary predictor of fire probability. Fuels-based fire probability maps can be used alongside existing data sources and prioritization frameworks by fire and fuels managers to inform questions of 1) what kind of fire year might this be, 2) where large fires are most likely to occur given an ignition, and 3) where resources should be focused. We provide examples of how maps can be used to improve prefire preparedness and planning to enhance suppression, facilitate annual targeting of fine fuels reductions, and support land use planning for implementation of landscape-scale fuels management. Proactively incorporating this new information into rangeland fire and fuels management can help address altered fire regimes threatening the region's wildlife and working lands.
