By Eli Lewis
Last month I had the opportunity to join the USDA Forest Service’s Fire Risk Reduction Infrastructure Team (WRRIT) in Northern California. The Forest Service led us on tours of Pluma National Forest and Tahoe National Forest, highlighting the impacts of the 2021 Dixie Fire (which burned nearly 1 million acres) and the 2020 North Complex Fire (which burned over 300,000 acres). .
As we traveled from place to place on our Burned Wounds Tour, miles of blackened forest flashed through my window. Entire mountain sides were burned and only tree trunks remained. We also spoke with wildland firefighters assigned to the North Complex Fire. They told us that while fires are known to move quickly uphill, surprisingly, these fires moved downhill just as quickly, taking many cities in Northern California with them. In Greenville, one such town, only a few charred structures remain today.
The week I spent with the WRRIT team helped me better understand the massive and far-reaching impacts of the wildfires in the region. He also put into context NASF’s role in supporting wildfire mitigation and suppression efforts across the country.
How the density of trees within a forest worsens the likelihood of catastrophic fire
USDA Forest Service employees who met with us noted that forest density is a significant complicating factor for wildfire management in the state. In Northern California, they said, the forests once looked very different.
One study found that across California, tree density in forested regions increased by 30% between 1930 and 2000, while forest biomass in the same regions declined, as indicated by a 19% reduction in basal area. These changes reflect a demographic change in forest structure: larger trees (>61 cm diameter at breast height) have declined, while smaller trees (< 30 cm) have increased.
Another study by UC Davis and the Forest Service found that ponderosa pine and mixed conifer forests in California had about 60 trees per acre 100 years ago. Today, in stark contrast, the same California forests have between 165 and 170 trees per hectare. However, another study estimates that pre-settlement tree density in California ranged from 24 to 132 trees per acre, with an average of 66 trees per acre. In the same forests today, tree density ranges from 115 to 308 trees per hectare, with an average of 160 trees per hectare. These researchers estimate that tree density in the state has increased between 80% and 600% in just 100 years.
Wildfire suppression efforts, while important for protecting human life and property, have also prevented the natural cycle of burning that many forest ecosystems would normally rely on to regenerate and restore balance. Unfortunately, instead of mimicking the appropriate and necessary burning cycles in these forests with active forest management, both natural fire regimes and critical management were excluded from these forests for many decades.
In fact, these forests have remained out of balance—with a severe lack of concern that they need to regenerate vigorously—for more than 60 years throughout the American West. These unbalanced forests are almost invariably what professional foresters call “overcrowded,” meaning they are too densely populated with trees. Fires in dense forests spread more easily and burn at higher temperatures, meaning they are more likely to cause extreme tree mortality and catastrophic damage to forest lands that cannot be restored. Densely stocked forests are also more susceptible to disease and pests, drought and heat stress, and other risk factors for excess tree mortality.
Forest management practices such as prescribed fire, thinning and timber harvesting can reduce fire risk to communities by creating fire-adapted ecosystems by ensuring a healthy number of trees per hectare. With mechanical thinning, for example, forest managers remove some trees in a forest to increase the availability of resources (such as sunlight, water, and space) for the more desirable trees that remain. This practice increases the space between trees in a stand, which means fires have less fuel and burn less fiercely. Thinning also helps strengthen the health and vitality of the trees remaining in the stand. When a fire occurs after a thinning, larger trees are more likely to survive the burn and the forest is able to regenerate and maintain long-term resilience.
By creating fuel breaks, forest managers can slow or stop fire progress by removing hazardous fuels in strategically located areas. They also create space to carry out firefighting operations. Prescribed fire is another tool used by natural resource professionals in carefully planned and managed situations to reduce the fuel load. Many forests are fire-adapted ecosystems, so reintroducing low-intensity fires through prescribed burning increases regeneration and maintains valuable wildlife habitat, reducing fire risk.
Allowing wildfires to burn indiscriminately in the forests of Northern California will never be an option. People living at the wild-urban interface in the region are only increasing. Letting the fires burn without any suppression or management strategy would be an absolute disaster for those Americans and their communities. For this reason alone, the need for greater forest management in these forests is dire.
Why the “all lands” approach is the only effective mitigation strategy for wildfires in the United States
Another theme of this trip was the importance of a “whole lands” approach to wildfires and forest management. A Forest Service district ranger in Plumas explained that if his agency reduces fuels on National Forest System (NFS) land, but private landowners or tribes on adjacent lands do not, those mitigation measures would do very little. to reduce fire severity and damage in general.
In our visit to the city of Greenville, which was burned by the Dixie Fire, we learned that the Forest Service had been conducting hazardous fuel treatments on NFS lands near the edge of the city, but there had been no coordinated effort to ensure that adjacent private lands were are also treated. If significant fuel reduction work had been done on those adjacent private forest lands, land managers on the ground say the outcome for Greenville would have been different.
Fuel treatments are needed on federal and non-federal lands to best protect communities. Transboundary fuel treatments complement each other and provide the greatest mitigation benefit to communities. At NASF, the principles of collaborative forest and wildfire management are central to our decision making and policy setting. State foresters believe we are most effective at reducing fire risk when federal and state agencies, tribes, and partner organizations collaborate and take a land-wide approach to reducing fire risk.
One of the best ways we can work to further mitigate fire risk is to empower private landowners with the tools and access to public assistance they need to implement forest management plans. The Forest Stewardship Program (FSP), administered by the Forest Service and delivered in partnership with state forest agencies and other partners, is the primary federal mechanism for supporting those landowners in making sustainable management decisions. FSP is also a tool to help landowners reduce fire risk.
Forest management plans are often paid for by FSP and provided to landowners free of charge. These plans give landowners a roadmap for reducing excess ground fuels, such as dead and downed trees, as well as reducing tree density per hectare, which also helps reduce fire severity and creates better fire conditions. suitable for prescribed fire treatments. In addition to individual forest management plans, Community Wildfire Protection Plans provide guidelines for reducing fire risk in a city, town or county.
As the intensity of wildfires increases across the US and mitigating their effects has become more challenging, we can still strive to protect our forests and communities. By using the forest management tools and planning resources available to us, we can make a difference that saves lives.
Eli Lewis is NASF’s policy coordinator. He can be contacted by email at elewis@stateforesters.org.
