Wildfire in the Sierra Nevada

Wildfire—Then and Now

Fire is a natural and essential process in the Sierra Nevada, but because many of our forests in the Sierra are overcrowded and unhealthy, many of today’s fires are not natural and often do not result in the same ecological benefits that historic fire or California Native American fire regimes did.

Recent fires, like the Rim Fire, King Fire and Butte Fire, have been larger and more severe than historic fires, and have caused a significant amount of damage to the resources the Region provides like clean air, water, wildlife habitat, recreational access, and carbon storage. In fact, more acres have burned in our current decade than in any other single decade on record across the west slope of the Sierra Nevada with one fire season remaining.

Graph of acres burned along the western slope of the Sierra Nevada every decade. The current decade has burned almost twice as much as the previous decade, and 2-3 times more than any prior decade

Wildfires of the past burned low to the ground and they burned fairly slowly, thinning out excess brush and smaller trees, and leaving larger trees to thrive without competition for resources like water and sunlight. These fires burned with mixed severity, mostly low and moderate severity, with some sporadic patches of high severity. In fact, on average, only about 20 percent of the burn area burned severely enough to kill large trees. In our current decade, however, that percentage has increased significantly, and rather than burning at high severity across a few small patches, the Sierra Nevada is seeing more fires burn unusually large swaths of the forest at high severity. Nearly 40 percent of the Rim Fire burned at high-severity, and almost half of the King Fire burned at high severity, leaving patches the size of the City of San Francisco with no living vegetation. Research is showing that those large patches of severely burned land are not growing back as forest, permanently shifting our lush, green forests, to dry, highly flammable shrub and grassland.

unhealthy, overcrowded Sierra Nevada forests are susceptible to high tree mortality and large, damaging wildfires, which have the following consequences: net carbon emission, poor air quality, public health consequences, habitat loss, decreased recreation, decreased groundwater storage, increased sedimentation in waterways, and reduced summer water flow

These large, damaging wildfires are jeopardizing California’s water system, placing communities at risk, and offsetting California’s air quality and climate goals. Learn more about these impacts by visiting the State of the Sierra Nevada’s Forests page.

A Path Forward

There is no “no fire” option in the Sierra Nevada, but there are steps that we can take to ensure our forests and communities are protected from the kinds of wildfires that do the most damage.

time-lapse of trees being removed from an overcrowded forest

Ecologically sound mechanical thinning removes excess brush and trees, reducing the amount of fuel available to burn. Treated areas also provide a safe location for fire crews to slow or stop the spread of fire. The time-lapse above shows thinning work being completed at the Sagehen Creek Field Station.

A prescribed fire underway

Prescribed fire and fire managed for resource benefit, under appropriate conditions, are important restoration tools that improve forest resilience and reduce the risk of large, high-severity fires. Every acre that burns under favorable conditions helps prevent the larger, unwanted fire and its larger, unwanted smoke event.

thinned and burned forest with open space

Watch a video series on the role that fire and thinning play in creating resilient Sierra Nevada forests.

Fortunately, the activities that reduce the risk for large, damaging wildfires also protect our forests from drought, insects, and disease. The Sierra Nevada Conservancy (SNC) is working closely with partners through the Sierra Nevada Region to increase the pace and scale of restoration treatments and return Sierra forests to a more resilient state.

The WIP is a coordinated, integrated, collaborative program to restore the health of California’s primary watershed through increased investment, expanded infrastructure, and needed policy changes. The primary goal of the WIP is to increase the pace and scale of restoration across the Sierra Nevada, and utilizing both prescribed and managed fire, and ecologically sound mechanical thinning are key activities for achieving that goal. The SNC also supports and encourages partnerships with California Native American tribes within the Region during the planning and implementation phases of these restoration projects.

Land management agencies in the Sierra Nevada have committed to a balanced fire program that will both reduce risks and realize the benefits of fire. In 2016, a team of federal and state agency officials worked with conservation and community fire protection groups to launch a new partnership focused on increasing the use of fire in California. The Sierra Nevada Conservancy is an active member of this partnership and is supporting prescribed and managed fire activities throughout the Sierra Nevada.