Chronic fire shortage': The paradox fueling mega-fires in the US

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Chronic fire shortage': The paradox fueling mega-fires in the US
Chronic fire shortage': The paradox fueling mega-fires in the US
Anonim

After so many years of smoke and record fires, people in western North America are familiar with wildfires. However, many questions arise about why wildfires are becoming more widespread and violent, and what can be done about it.

Is climate change fueling these fires? Does the long fight against each fire play a role? Should we leave more fires to burn? What can be done about the vulnerability of western forests to wildfires and climate change?

We invited 40 firefighters and forest ecologists from the western United States and Canada to review the latest research and answer these questions in a selection of papers published on August 2, 2021. Together, we are deeply concerned about the future of western forests and communities in the face of climate change.

So why are wildfires getting worse?

Climate change plays a big role in this. Summer seasons of wildfires are already 40-80 days longer on average than they were 30 years ago. Annual droughts are more severe, making it easier for fuel to dry out, ignite and spread fires.

Extreme weather events, characterized by dry fuel, thunderstorms and high winds, are also increasing in frequency and are essential ingredients for the rapid growth of fires, as evidenced by the Bootleg Fire in Oregon and record fires in California and Colorado in 2020.

Ironically, chronic fire shortages in western landscapes also contribute to increased severity of fires and vulnerability to wildfires. This allows dry scrub, living and dead trees to accumulate, and since there are more people in the wild who can ignite a fire, the pressure to fight each wildfire increases the risk of extreme fires.

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The challenge of fighting every forest fire

Historically, fire has been a regular visitor to most forests in the West, with the exception of humid areas such as the Pacific Northwest and British Columbia. Frequent or intermittent fires caused by indigenous fires and lightning strikes have created networks of grasslands, shrubs and regenerating forests of all ages.

Past fires affect how subsequent fires burn and what they leave behind. For example, the practice of burning indigenous peoples not only improves cultural resources and wildlife habitat, but also reduces the amount and cohesion of fuels that cause large and severe forest fires.

Likewise, focal fires from lightning create forest landscapes that are less likely to burn all at once.

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In the United States and Canada, all forest fires are effectively suppressed with the exception of 2-3 percent. However, this small percentage of fires occur during the height of each fire season, when dry conditions and extreme fire weather discourage even the most aggressive suppression efforts.

By inadvertently focusing on the short-term risks of wildfires, the United States predisposes forests to catch fire in the most adverse conditions. Active fire suppression contributes to what is often called the bushfire paradox - the more we prevent fires in the short term, the worse bushfires become when they return.

In a new study, Paul Hessburg et al. Explain how fire managers can mitigate the severity of future fires by managing fire-free forests to increase resilience to wildfires and drought.

Management approaches include thinning dense forests, reducing fuel through prescribed burns, and managing wildfires to restore a more typical structure of forests, grasslands, shrubs and woodlands.

In a second article, Keela Hagmann and her co-authors describe how more than a century of fire exclusion and past forest management practices have compromised forest biodiversity, social and environmental values, including culturally significant resources, water quantity and quality, carbon storage stability, recreation and air quality. …

For example, the exclusion of fire threatened aspen stands - hotbeds of biodiversity for everyone from bears to butterflies. The increase in forest cover diverts water from the meadows below the slope, which allows coniferous forests to further invade the aspen habitat.

The way forward

Amid the frightening reality of climate change and violent wildfires, the western forests have a way forward.

In a third article, Susan Prichard and her coauthors look at how adaptive forest management approaches have helped improve resilience to wildfires and climate change.

There is strong scientific evidence that fuel reduction measures - including deforestation, burnout as intended, indigenous cultural burnout, and managed wildfires - are effective approaches to mitigate the future impact of wildfires on Western forests.

However, surveyors cannot count on these methods to be effective if they are applied to only a small fraction of the forested landscape of the West.

When used together, thinning and prescribed burning in dry pine stands and dry and wet mixed coniferous forests have been shown to be highly effective in reducing forest fire damage.

However, this type of processing is not suitable for all types of forest. Fire managers in some wilderness areas and national parks have allowed lightning-initiated fires to burn under certain wind and weather conditions.

For the past 40+ years, these fires have been allowed to burn and re-burn landscapes, which generally limited the size and strength of subsequent wildfires.

Given the vast variety of forests in the West, there is no one-size-fits-all solution. However, in forests that have historically supported more frequent fires, revival and continued cultural burning practices, prescribed burning, and forest thinning, combined with prescribed burning, can reduce crowding and the potential for severe fires.

Thinning and prescribed burns are not always appropriate or feasible. In reality, only a fraction of the landscape can be processed this way. Allowing forest fires to burn over a larger area in moderate weather is also part of the solution.

Promoting the resilience of western forests will require our society to forge a new relationship with fire by creating fire-adapted communities and seeking opportunities to practice controlled fires in western forest landscapes.

In an era of warmer, drier summers and longer fire seasons, there is no solution without fire or smoke. The current approach to fire management creates unreasonably high rates for western forests.

There is no doubt that the future of the western forests is fiery. How we live with fire depends only on us.

Susan J. Pritchard, Research Fellow, Forest Ecology Department, University of Washington; Keela Hagmann, Assistant Professor, University of Washington, and Paul Hessburg, Science Ecologist, US Forest Service.

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