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Map showing fire history and severity of the 2011 Miller Fire in the Gila National Forest. Most of the fire was low to moderate severity particularly within areas that had burned prior to 2011. Some of the areas that did experience high severity fires were pinyonjuniper stands that had not burned in the last century. Fire severity was derived from the Monitoring Trends in Burn Severity database (http://www. mtbs.gov/). 

Map showing fire history and severity of the 2011 Miller Fire in the Gila National Forest. Most of the fire was low to moderate severity particularly within areas that had burned prior to 2011. Some of the areas that did experience high severity fires were pinyonjuniper stands that had not burned in the last century. Fire severity was derived from the Monitoring Trends in Burn Severity database (http://www. mtbs.gov/). 

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Technical Report
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Fire suppression has been the dominant fire management strategy in the West over the last century. However, managers of the Gila and Aldo Leopold Wilderness Complex in New Mexico and the Saguaro Wilderness Area in Arizona have allowed fire to play a more natural role for decades. This report summarizes the effects of these fire management practices...

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... Unplanned ignitions have been successfully used to achieve resource objectives within some southwestern regions (Hunter et al., 2014); such "managed wildfires" represent a viable option for repeated fire entry into large postfire forest patches (North et al., 2012, under weather conditions that are milder than those under which most wildfires currently burn. Following policy change in 2009, the use of this management option has increased in other regions of the western US . ...
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ContextSpatial patterns of high-severity wildfire in forests affect vegetation recovery pathways, watershed dynamics, and wildlife habitat across landscapes. Yet, less is known about contemporary trends in landscape patterns of high-severity burn patches or how differing federal fire management strategies have influenced such patterns.Objectives We assessed fires managed for ecological/resource benefit and fires that are fully suppressed and investigated: (1) whether spatial patterns of high-severity patches differed by management strategy, (2) whether spatial patterns were related to fire size and percent high-severity fire, and (3) temporal trends in spatial patterns.Methods We examined high-severity spatial patterns within large fires using satellite-derived burn severity data from 735 fires that burned from 1984 to 2017 in Arizona and New Mexico, USA. We calculated a suite of spatial pattern metrics for each individual fire and developed a method to identify those which best explained variation among fires.ResultsCompared to managed fires, spatial pattern metrics in suppression fires showed greater patch homogeneity. All spatial pattern metrics showed significant relationships with fire size and percent high-severity fire for both management strategies. Mean annual spatiotemporal trends in suppression fires have moved toward smaller, more complex, fragmented patches since the early 2000s.Conclusions Increases in fire size and proportion high-severity fire are driving more homogenous patches regardless of management type, with percent high-severity more strongly driving average temporal trends. Anticipated shifts in fire size and severity will likely result in larger, more contiguous, and simple-shaped patches of high-severity fire within southwestern conifer forests.
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Nearly a century of fire suppression in most forested land of the United States has limited researchers’ ability to construct and rigorously test conceptual models of forest structural development in mixed-conifer ecosystems. As a result, land managers must rely on conceptual models of forest development that may overemphasize idealized stand structures and developmental pathways, which ultimately hampers management of many forest systems for resilience to future climate change impacts. We sought to determine the relative importance of fire history (frequency, severity, and time since fire) and biophysical variables on forest structural diversity and development. Importantly, we conducted our study in an ecosystem with a contemporary active fire regime where wildland fire has been managed as an ecosystem process for four decades. Using data from unburned (≥80 years since fire), once-burned and twice-burned mixed-conifer forests in the Bob Marshall Wilderness of Northwest Montana, we conducted a hierarchical clustering analysis to identify forest stand structure classes. We then used a Classification and Regression Tree analysis, combined with other post-hoc analyses, to elucidate the biophysical and disturbance history drivers that lead to each structure class. The cluster analysis revealed six forest structure classes. The CART analysis indicated that time since fire plays a large role in determining forest structure, but at intermediate time scales structure is further shaped by repeat fires and interactions with biophysical variables. The CART and post-hoc analyses did not, however, indicate a singular fire history or biophysical pathway to any one structure class. We synthesize our results in a conceptual model of forest structural development under an active fire regime. This model supports existing theory that succession following severe fire plays a large role in shaping forest structure. It also recognizes the role of fire at variable severities and frequencies, the physical environment, and tree community composition in influencing forest structural development. The complexity of forest structure and development generated by an active fire regime points to the need to incorporate a process-based view of wildfire if the goal is to manage for improved resiliency and adaptive capacity to future climate change impacts.
... Keane et al. 2002;O'Connor et al. 2014;Taylor et al. 2014). In the 1970s, land managers began using natural ignitions to restore fire regimes and help reduce hazardous fuels (van Wagtendonk 2007;Hunter et al. 2014), particularly where mechanical treatments were not a viable option (North et al. 2012). Since then, federal fire policy has become increasingly flexible, with the 2009 Guidance for Implementation of Federal Wildland Fire Management Policy (henceforth 2009 Policy Guidance; Fire Executive Council 2009) being a significant turning point. ...
... In reaching treatment goals, fire is a crucial tool to improve forest conditions, reduce fuels and decrease the threat of large, high-severity wildland fires (Vaillant and Reinhardt 2017). Fire managers have used natural ignitions as a key component in the restoration of historical forest conditions and fuel loadings, with notable success after multiple fires that burned at low to moderate severity (Hunter et al. 2011(Hunter et al. , 2014Huffman et al. 2017;SIT-209 2018). A widespread use of natural ignitions in the Grand Canyon National Park has also promoted floristic diversity (Laughlin et al. 2005). ...
... Though some land managers have increasingly used wildland fires to meet resource objectives since the 1970s (van Wagtendonk 2007;Hunter et al. 2014), managers more commonly resort to full suppression strategies. In many instances, this was by design owing to restrictive land-management policies Meyer et al. 2015), many of which are being rewritten to be more inclusive of using wildland fires to meet resource objectives (e.g. ...
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In 2009, new guidance for wildland fire management in the United States expanded the range of strategic options for managers working to reduce the threat of high-severity wildland fire, improve forest health and respond to a changing climate. Markedly, the new guidance provided greater flexibility to manage wildland fires to meet multiple resource objectives. We use Incident Status Summary reports to understand how wildland fire management strategies have differed across the western US in recent years and how management has changed since the 2009 Guidance for Implementation of Federal Wildland Fire Management Policy. When controlling for confounding variation, we found the 2009 Policy Guidance along with other concurrent advances in fire management motivated an estimated 27 to 73% increase in the number of fires managed with expanded strategic options, with only limited evidence of an increase in size or annual area burned. Fire weather captured a manager’s intent and allocation of fire management resources relative to burning conditions, where a manager’s desire and ability to suppress is either complemented by fire weather, at odds with fire weather, or put aside due to other priorities. We highlight opportunities to expand the use of strategic options in fire-adapted forests to improve fuel heterogeneity.
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