Today the risk of wildfire is increasing across the United States, particularly in the state of California. In the first of a three-part blog series, Ecosulis Biodiversity Lead Vance Russell and the Environmental Defense Fund's Eric Holst examine the trend, and discuss the difference between a bad fire and a good fire.
Risk and response
As the Earth's climate continues to warm, so the risk of forest stress and die-off, vegetation transformation and wildfire is rising across the United States and other parts of the world.
Increasing wildfire risk is already the reality for much of the western United States, particularly in California, the Pacific Northwest, the mountains of the desert Southwest and the Southern Rockies, where warmer temperatures and drier conditions are major contributors.
The largest (Mendocino Complex, 1850 square kilometres / 700 square miles) and deadliest (Camp, 85 deaths) wildfires in California history took place in 2018. Perhaps it's a sad commentary on the human psyche that it took disasters of this magnitude to mobilise action against such threats to lives, infrastructure and wild nature. More than $1 billion will now be invested in California over the next five years, with multiple efforts to develop and implement wildfire mitigation projects.
This increase in funding is surely good to see, but raises a series of pertinent questions. Will these efforts really accomplish their objective? Are there enough projects in the pipeline, and does California have the capacity to carry them out? How can an evidence base be built to prove that funding is really reducing the size and detrimental effect of forest fires on Californian residents and biodiversity?
To answer these questions, first we need to analyse wildfires a little more.
Figure 1. Forest resilience + rural vitality = sustainable forests that provide water, biodiversity and tourism,
and which are also resistant to serious wildfires and climate change.
Bad fire vs. good fire
When their consequences are looked at objectively, wildfires can either be classified as "good" or "bad". Examining some real-life examples of Californian fires can help us tease the two apart.
The sustainable forests of the Sierra Nevada are typically biodiverse and heterogeneous, resilient to wildfire, climate change and disease (North, et al., 2009). The rural communities based here are vibrant, demographically stable and economically self-sufficient, with revenue streams that that go beyond tourism and logging (Figure 1).
The Camp and Mendocino Complex fires of 2018, which both consumed extensive areas of Sierra Nevada forest, neatly illustrate the varying impact that wildfire can have on people, property and biodiversity.
Starting in November 2018, the Camp Fire was fuelled by a bumper crop of dry grass generated by the preceding wet winter and scorching summer. It quickly grew into a conflagration that swept into the town of Paradise, creating a firestorm reminiscent of those caused by the bombing of German cities in WWII.
The fire eventually ravaged over 600 square kilometres (230 square miles) of land, destroyed nearly 19,000 structures, and tragically caused the deaths of 85 Paradise residents, many of whom were senior citizens and couldn't leave the town in time. As the deadliest wildfire in California history, this was clearly a "bad" fire.
By contrast, the Mendocino Complex Fire, which burned from July through to November, ravaged around 1850 square kilometres (700 square miles) of forest. However, it "only" destroyed 280 buildings - half of which were residential - and caused the death of one firefighter. Lake County, where much of the fire burned, has endured eight fires in the past three years, affecting half the county's territory.
While a single death is still clearly a tragedy and loss of infrastructure is always costly, some would consider portions of the Mendocino fire to have been a success. Forage for cattle was exceptionally good in 2019, while wildflowers, chaparral species (especially those that are serotinous) and wildlife are all thriving.
Given the ferocity with which they burned, it is almost impossible to speculate what could have prevented both the Camp and Mendocino Complex fires from starting or spreading. However, the Mendocino fire may have done more good than bad, revitalising brush and chaparral that had not burned in years due to fire suppression.
The Mendocino Complex Fire from the air.
Letting it burn
An examination of the Rim Fire of 2014 is also instructive in terms of the good fire vs. bad fire debate. It was fast and furious in the Sierra Nevada's Stanislaus National Forest, where fire had been suppressed for years. But when it approached the border of Yosemite National Park, where the park service has long practiced controlled burning and intentionally allowed less serious wildfires to burn, the fire dropped from the forest crown to the floor and did far less damage.
For many years it was incredibly rare to simply let wildfires burn — only 0.4% of all ignitions in the United States between 1998 and 2008 were allowed to burn without intervention. In this National Public Radio article, a district ranger in the Sierra National Forest recounts letting the Lions Fire (June-July 2018) burn because it was located away from property and was in an area populated with dead (i.e. highly flammable) trees. While the fire eventually had to be suppressed due to high winds, it lowered the risk of a more serious fire in the future.
Letting wildfires burn is slowly starting to become more common practice. Figure 2 outlines a framework where fires of low to medium intensity occurring in wilderness and wildland urban interface (WUI) are allowed to burn. The prescribed fire continuum depicted in the same figure shows where more prescribed fire and thinning should be applied to reduce the risk of huge fires close to urban areas.
Figure 2. Fire burn matrix. Prescribed fire (Rx) continuum or prescribed fire continuum vs. when to let wildfires burn.
WUI=Wildland Urban Interface.
Back to the future
Between 1920 and 1950, between 40,000 and 200,000 square kilometres (15,000 and 77,000 square miles) of forest was allowed to burn in the United States every year. Yet by the 1950s, annual burning was reduced to less than 8000 square kilometres (3000 square miles) (Struzik, 2019).
In California, before fire suppression was widely practiced, around 15,500 square kilometers (6000 square miles) of forest burned every year. This is almost double the amount of forest that burned in the state in 2018, which was a bad year for fires.
Most of these historic Californian wildfires were low intensity, low impact fires. Due to fire suppression and air quality restrictions, fires such as this rarely happen any more. But they still provide an instructive lesson.
By thinning out smaller diameter trees in prioritised WUI and fuel breaks, employing controlled burning over larger landscapes and letting remote fires burn, Californian forests could be restored to a far more fire resilient state, thereby avoiding many future tragedies. Yet only a Marshall plan-level of funding, planning, mobilisation and monitoring will result in such effective threat mitigation.
In the next post in this series we will examine how a combined process of prescribed fire, careful wildfire management and thinning could practically be employed to lower the risk of another "bad" Californian fire.
Want to know more?