The normal fire environment—Modeling environmental suitability for large forest wildfires using past, present, and future climate normals

Davis, Raymond J.; Yost, Andrew; Belongie, Cole; Cohen, Warren B.

doi:10.1016/j.foreco.2017.01.027

Cited by 80 publications

(64 citation statements)

References 71 publications

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“…The region has experienced short intervals between recent high‐severity fires coupled with intensive timber management in this mixed‐severity fire regime area, and the likelihood of further shortening of fire‐return intervals with climate change (Davis et al. ). Even where climate is suitable to sustain dense mature forests, early‐seral and non‐forest conditions may perpetuate because of a cycle of short‐interval repeat burning and timber harvest and have dramatic impacts on biodiversity and wildlife habitats (Lindenmayer et al.…”

Section: Discussionmentioning

confidence: 99%

Mixed‐severity wildfire and habitat of an old‐forest obligate

et al. 2019

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The frequency, extent, and severity of wildfire strongly influence the structure and function of ecosystems. Mixed‐severity fire regimes are the most complex and least understood fire regimes, and variability of fire severity can occur at fine spatial and temporal scales, depending on previous disturbance history, topography, fuel continuity, vegetation type, and weather. During high fire weather in 2013, a complex of mixed‐severity wildfires burned across multiple ownerships within the Klamath‐Siskiyou ecoregion of southwestern Oregon where northern spotted owl (Strix occidentalis caurina) demographics were studied since 1990. A year prior to these wildfires, high‐resolution, remotely sensed forest structural information derived from light detection and ranging (lidar) data was acquired for an area that fully covered the extent of these fires. To quantify wildfire impact on northern spotted owl nesting/roosting habitat, we fit a relative habitat suitability model based on pre‐fire locations used for nesting and roosting, and forest structure variables developed from 2012 lidar data. Our pre‐fire habitat suitability model predicted nesting/roosting locations well, and variable response functions followed known resource selection patterns. These forests had typical characteristics of old‐growth forest, with high density of large live trees, high canopy cover, and complex structure in canopy height. We projected the pre‐fire model onto lidar data collected two months post‐fire to produce a post‐fire suitability map, which indicated that >93% of pre‐fire habitat that burned at high severity was no longer suitable forest for nesting and roosting. We also quantified the probability that pre‐fire nesting/roosting habitat would burn at each severity class (unburned/low, low, moderate, high). Pre‐fire nesting/roosting habitat had lower probability of burning at moderate or high severity compared to other forest types under high burning conditions. Our results indicate that northern spotted owl habitat can buffer the negative effects of climate change by enhancing biodiversity and resistance to high‐severity fires, which are predicted to increase in frequency and extent with climate change. Within this region, protecting large blocks of old forests could be an integral component of management plans that successfully maintain variability of forests in this mixed‐ownership and mixed‐severity fire regime landscape and enhance conservation of many species.

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Section: Discussionmentioning

confidence: 99%

Mixed‐severity wildfire and habitat of an old‐forest obligate

et al. 2019

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“…The model outputs a map in which each grid cell represents the suitability for the modelled condition (i.e., type conversion) to occur, ranging from 0 to 1. In addition to its most common application, species distribution modelling (Franklin, ), this modelling approach has been successfully used to map the distribution of fire probability (e.g., Davis, Yang, Yost, Belongie, & Cohen, ), structure risk to wildfire (e.g., Syphard, Keeley, Massada, Brennan, & Radeloff, ), and ignition probability (e.g., Syphard & Keeley, ).…”

Section: Methodsmentioning

confidence: 99%

Drivers of chaparral type conversion to herbaceous vegetation in coastal Southern California

Syphard

Brennan²,

Keeley

2018

Diversity and Distributions

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Aim: In Southern California, native woody shrublands known as chaparral support exceptional biodiversity. However, large-scale conversion of chaparral into largely exotic herbaceous cover is a major ecological threat and serious conservation concern. Due to substantial uncertainty regarding the causes and extent of this vegetation change, we aimed to quantify the primary drivers of and map potentially vulnerable locations for vegetation type conversion from woody into herbaceous cover.Location: Santa Monica Mountains National Recreational Area, Southern California, USA.Methods: We used air photograph image interpretation to quantify the extent to which chaparral shrublands transitioned to herbaceous cover from 1943 to 2014 across nearly 800 randomly located plots. Comparing plots that remained chaparral to those that converted to herbaceous cover, we performed hierarchical partitioning to quantify the independent contribution of a range of explanatory variables, and then used classification trees to explore variable interactions. We also developed a spatial model to create a seamless map delineating relative probability of type conversion. Results:Of the original plots that were chaparral in 1943, 284 (36%) changed cover by 2014, with 79 completely converting, and 142 mostly converting to herbaceous cover. The primary mechanism behind shrubland decline and replacement was short intervals between fires (<=10 years), and type conversion was most likely to occur in arid parts of the landscape with low topographic heterogeneity and close proximity to trails and roads. Predictive maps delineated several hotspots with environmental conditions similar to those of type-converted plots. Main conclusions:Chaparral type conversion is a widespread conservation concern, and results here suggest that short-interval fire and landscape disturbance are the most likely factors to exacerbate it, particularly in water-limited portions of the landscape where chaparral is subject to greater physiological stress and slower recovery.Reducing fire ignitions and mapping vulnerable areas may be important strategies for prevention. K E Y W O R D Sdisturbance, Mediterranean, site aridity, vegetation change, wildfire | 91 SYPHARD et Al.

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“…Barbero et al (2015) projected that the annual probability of very large fires will increase by a factor of 4 in 2041 to 2070 compared to 1971 to 2000. Projections by Davis et al (2017) suggested that the proportion of forests highly suitable for fires >40 ha will increase by >20% in the next century for most of Oregon and Washington, but less so for the Coast Range and Puget Lowlands. The largest projected increases were in the Blue Mountains, Klamath Mountains, and East Cascades.…”

Section: Fire Projections By Empirical Modelsmentioning

confidence: 99%

Changing wildfire, changing forests: the effects of climate change on fire regimes and vegetation in the Pacific Northwest, USA

2020

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Background: Wildfires in the Pacific Northwest (Washington, Oregon, Idaho, and western Montana, USA) have been immense in recent years, capturing the attention of resource managers, fire scientists, and the general public. This paper synthesizes understanding of the potential effects of changing climate and fire regimes on Pacific Northwest forests, including effects on disturbance and stress interactions, forest structure and composition, and post-fire ecological processes. We frame this information in a risk assessment context, and conclude with management implications and future research needs. Results: Large and severe fires in the Pacific Northwest are associated with warm and dry conditions, and such conditions will likely occur with increasing frequency in a warming climate. According to projections based on historical records, current trends, and simulation modeling, protracted warmer and drier conditions will drive lower fuel moisture and longer fire seasons in the future, likely increasing the frequency and extent of fires compared to the twentieth century. Interactions between fire and other disturbances, such as drought and insect outbreaks, are likely to be the primary drivers of ecosystem change in a warming climate. Reburns are also likely to occur more frequently with warming and drought, with potential effects on tree regeneration and species composition. Hotter, drier sites may be particularly at risk for regeneration failures. Conclusion: Resource managers will likely be unable to affect the total area burned by fire, as this trend is driven strongly by climate. However, fuel treatments, when implemented in a spatially strategic manner, can help to decrease fire intensity and severity and improve forest resilience to fire, insects, and drought. Where fuel treatments are less effective (wetter, high-elevation, and coastal forests), managers may consider implementing fuel breaks around high-value resources. When and where post-fire planting is an option, planting different genetic stock than has been used in the past may increase seedling survival. Planting seedlings on cooler, wetter microsites may also help to increase survival. In the driest topographic locations, managers may need to consider where they will try to forestall change and where they will allow conversions to vegetation other than what is currently dominant.

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The normal fire environment—Modeling environmental suitability for large forest wildfires using past, present, and future climate normals

Cited by 80 publications

References 71 publications

Mixed‐severity wildfire and habitat of an old‐forest obligate

Mixed‐severity wildfire and habitat of an old‐forest obligate

Drivers of chaparral type conversion to herbaceous vegetation in coastal Southern California

Changing wildfire, changing forests: the effects of climate change on fire regimes and vegetation in the Pacific Northwest, USA

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