Using historical aerial imagery to assess non-conifer vegetation type change under fire exclusion

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Using historical aerial imagery to assess non-conifer vegetation type change under fire exclusion

Although vegetation types other than conifer forests make up the majority of burned area in California wildfires, relatively few studies quantify the drivers and patterns of vegetation change in these ecosystems. The impacts of fire exclusion on non-conifer systems remain poorly understood, and the relative influence of fuels compared to factors like climate change or type conversion on fire behavior is largely unknown. To address this knowledge gap, the authors investigated large-scale vegetation change as a possible driver of current trends in fire behavior within mixed-hardwood and shrub-dominated ecosystems in central and coastal Northern California.

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Using Stand Density Index (SDI) as a stocking guide in frequent fire forests

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Using Stand Density Index (SDI) as a stocking guide in frequent fire forests

Quantification of competition levels in forest stands benefits assessments of stand health, vulnerability to stressors, and prediction of future stand dynamics. Because different forests have different carrying capacities that can be maintained given differences in site productivities, it is important to consider stocking in terms that are relative to these maximum levels. Stand Density Index (SDI) is a common metric of competition in temperate forests of Western North America, originating in 1933 and gaining widespread use within the field of forestry throughout the 20th century. The authors of this study synthesized the large body of published literature on SDI since its introduction in 1933.

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Fire suppression biases fires to be more extreme

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Fire suppression biases fires to be more extreme

Decades of fire suppression have increased fuel loads and fire severity, leading to the “fire suppression paradox”—by suppressing fires we make fires harder to put out in the future. However, in this study, the authors show a separate impact of fire suppression that may cause even greater increases in average fire severity than climate change or fuel accumulation.

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Wildfire Following Severe Tree Mortality in Frequent Fire Forests: A Research Summary and Call for Proactive Management : Research Brief

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Wildfire Following Severe Tree Mortality in Frequent Fire Forests: A Research Summary and Call for Proactive Management : Research Brief

This Overview Article summarizes research relevant to understanding short- and longer-term effects of massive tree mortality in what were historically frequent fire forests of California, presents results on fire severity from a recent wildfire that burned through severe tree mortality, and makes management recommendations for reducing future tree mortality and increasing forest resilience and adaptation to climate change.

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Distinguishing Disturbance from Perturbations in Fire Regimes: Research Brief

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Distinguishing Disturbance from Perturbations in Fire Regimes: Research Brief

If the fire has characteristics that do not fit the historical fire regime with which the fire-adapted ecosystem has developed, then it may impact resilience and cause a shift in ecosystem characteristics.

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Are historical fire regimes compatible with future climate? Implications for forest restoration: Research Brief

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Are historical fire regimes compatible with future climate? Implications for forest restoration: Research Brief

Future climate-induced shifts in fire regimes and plant distributions could uncouple vegetation from the fire regimes for which they are adapted. The brief discusses changes to fire-adapted plant communities under modeled climate change scenarios and their implications on the Kaibab Plateau landscape.

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Maximum Fire Elevation in the Sierra Nevada Has Increased Over the Past Century: Research Brief

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Maximum Fire Elevation in the Sierra Nevada Has Increased Over the Past Century: Research Brief

Using a geodatabase, researchers found that the maximum elevation extent of wildfires and the probability of wildfire occurrence above 3000 m have increased over the last century in the Sierra Nevada. This trend may accelerate vegetation shifts towards upper montane forest types in current subalpine systems. 

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Photo courtesy of Sasha Berleman 

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Increasing Fire Activity for Arid California: Different Fire Trends from Different Fire Drivers: Research Brief

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Increasing Fire Activity for Arid California: Different Fire Trends from Different Fire Drivers: Research Brief

Study results from arid regions in Southern California show how fire trends differ based on unique sets of circumstances. This brief discuses how combinations of direct drivers (like powerline and roadside ignitions),  indirect drivers (like invasive grasses, air pollution, and landscape fragmentation terrestrial intactness) and unknown factors cause diversity in fire trends.

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Increased fire area and severity in the Sierra Nevada warrant fuels reductions and wildland fire use

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Increased fire area and severity in the Sierra Nevada warrant fuels reductions and wildland fire use

The authors assessed relative and absolute changes in wildfire area and severity in seven forest types arrayed along an elevational gradient in the Sierra Nevada and adjacent forested mountains. Findings suggest that there is a major fire “deficit” in the greater Sierra Nevada Region, across all major forest types. However, the nature of this deficit differs among forest types.

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Influence of post-fire vegetation and fuels on fire severity patterns in reburns: Research Brief

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Influence of post-fire vegetation and fuels on fire severity patterns in reburns: Research Brief

Results from a 2016 study by Coppoletta and others suggests that in areas where fire regimes and forest structure have been dramatically altered, contemporary fires have the potential to set forests on a positive feedback trajectory with successive reburns, one in which extensive stand-replacing fire could promote more stand-replacing fire.

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Predicting Future Fire Regimes: Still a Long Way to Go: Research Brief

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Predicting Future Fire Regimes: Still a Long Way to Go: Research Brief

In a review article by Jon Keeley and Alex Syphard, examples from California show that fire regimes are sensitive to geographic and seasonal variation in the climate signal and that many factors will confound the ability to model future conditions.

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Proximate Causes of Abrupt Fire-Regime Changes: Research Brief

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Proximate Causes of Abrupt Fire-Regime Changes: Research Brief

In many past and present ecosystems, changes in animal, plant, and human communities have been more influential in rapid local fire regime disruption than climate. The good news is that, unlike climate change, these direct, proximate community causes can be practically addressed by fire and resource managers.

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Resistance to invasives and altered fire regimes differs between cold and hot desert shrublands: USGS Research Brief

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An article provides an overview of key factors, concepts and tools to understand the ecological resistance to biological invasion and resilience to fire of desert shrublands of North America. 
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Interactions among wildland fires in a long-established Sierra Nevada natural fire area: Research Brief

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 A   2009  study  by  Collins  et  al.  suggests  that  freely   burning  fires  in  upper  elevation  mixed-­‐conifer   forests  of  the  Sierra  Nevada  may  effectively   regulate  fire-­‐induced  effects  across  an  entire   landscape.
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Human Influence on California Fire Regimes: USGS Research Brief

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Researchers studied the human influence on fire regimes at the WUI using California Department of Forestry and Fire Protection (CDF) data from a majority of counties in the state, coupled with associated housing and other human infrastructure data.
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