Forest Restoration

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Before forest restoration work done near Wawona.

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After forest restoration work done near Wawona.

 

 

The lower-elevation forests of Yosemite evolved with frequent, generally low- to moderate-severity fires lit by lightning or native peoples. This process kept fuels and vegetation low, maintaining and enhancing a landscape of park-like forests, broad meadows, and open oak woodlands. Starting in the mid-19^th century, European colonizers enforced a policy of fire suppression. Without fire, conifers grew into the maintained meadows and oak groves, and forests grew increasingly dense. In the 1970s, park managers began to recognize the integral role of fire in the management and overall health of the park’s ecosystems and initiated a prescribed fire and managed wildfire program. Today, Yosemite’s fire management program balances the protection of life, property, and other important resources with the restoration of fire as a natural process and the inclusion of traditional ecological knowledge.

How is Yosemite trying to restore forests?

Fire suppression has resulted in forests with fuel loads so unnaturally high that when a wildfire comes through it can be dangerous to communities, firefighters, and ecosystem health. Prescribed fire and the management of natural lightning ignitions for resource benefit are the park’s primary tools for restoring forests. However, mechanical thinning may be necessary around high-risk areas such as communities, evacuation routes, and sequoia groves.

Why and where are trees cut?

1. Meadow restoration: smaller trees are removed from historic meadow areas to promote plant and wildlife biodiversity, increase water quality, store carbon, and improve flood control. Meadow restoration objectives are defined in the Merced River Plan (MRP) and the Tuolumne River Plan (TRP).

2. Biomass removal: smaller trees and dead and downed material are removed from forests in preparation for prescribed fire, to provide greater firefighter safety in case of a wildfire, and to reduce the risk of catastrophic high-severity wildfire. Treatments generally occur within 200 feet of roads and other high-risk areas. Fuels and forest structure objectives are defined in the Fire Management Plan (FMP).

3. Hazard tree removal: trees that have the potential to fall and strike a person, building, or structure are removed to protect structures, roads, and visitor accessibility.

4. Scenic vista management: trees are removed to restore historic scenic vistas blocked by conifers that have grown in with the suppression of native burning and lightning-caused fires. Select trees are removed to restore the historic scenic vista and improve visitor experience. Historic scenic vistas are defined in the Scenic Vista Management Plan, MRP, and TRP.

5. High-value tree protection: smaller trees are removed around trees that are biological and cultural keystone species, specifically California black oak and giant sequoia. This is defined in the MRP and the FMP.

Are mechanical treatments commercial logging?

No, commercial logging is commodity-driven to extract timber for profit. The park does not conduct commercial logging.

Where does the wood go?

Smaller materials such as branches and broken logs may be piled and burned. Larger material that can be transported is trucked off-site to different places depending on its condition and size. Most material is taken either to a wood products plant where it is used for wood shavings, or a co-generation plant where the wood is burned for electricity. Some material is chipped for use in park ecological restoration projects. The remaining green trees are taken to a sawmill, mostly to be turned into fencing or construction material. Any proceeds from taking wood to a facility is incorporated back into the project to offset project costs. Neither the NPS nor contractors receive payment from the material.

Where does the money for projects come from?

Biomass removal projects are funded through California Climate Investments and the Wildlife Conservation Board as part of California’s commitment to protect carbon stored in forests. Projects are jointly administered by Yosemite National Park and Mariposa County Resource Conservation District.

Scenic vista restoration is primarily funded by Recreation Fee dollars (entrance fee dollars).

Yosemite Conservancy has funded scenic vista restoration and restoration in the Merced Grove.

Hazard tree removal is funded primarily through Recreation Fee dollars.

Forest restoration associated with fire management is funded through Congressionally allocated dollars and Bipartisan Infrastructure Law.

Will mechanical thinning treatments stop a wildfire?

The primary objectives for mechanical thinning in the park are to prepare areas for future prescribed burns and provide greater firefighter safety in the event of a wildfire. While a single treated area will likely not stop a wildfire, strategically placed treatments can slow its momentum and help firefighters in their suppression efforts.

Fuel loads accumulate over time, so the same area needs to be treated periodically to maintain its effectiveness. Research shows that most fuels reduction treatments start to lose their effectiveness after 8-20 years, depending on the forest type. A combination of mechanical treatments and prescribed fire has been shown to be the most effective at reducing fuel loads and wildfire hazard.

How do projects affect wildlife?

Conservation measures are taken for species of concern (e.g., Pacific fisher, California red-legged frog, great gray owl) before any treatment takes place, which may include surveying for nesting or denning habitat, avoiding known habitat areas, treating outside of nesting or breeding seasons, or other considerations. High-value habitat features like large snags with broken tops or large cavities are preserved wherever possible.

Fire suppression, along with climate change, habitat fragmentation, and other human-caused factors pose serious threats to the continued existence of many wildlife species in the park. Mechanical treatments enable the safe reintroduction of fire to restore degraded wildlife habitat. During a prescribed burn some areas may burn intensely while others may burn very little or not at all, creating varied habitat structures that support a diversity of different wildlife species.

Learn more about wildlife and fire.

How do projects affect cultural resources?

Mechanical treatments and prescribed fire can help reduce the chance that archeological sites are damaged from a high-severity wildfire. Input from cultural resources specialists and affiliated tribes inform site-specific plans to ensure the conservation and restoration of cultural sites within treatment areas. Pre-contact artifacts have likely survived many low-severity fires but are at risk of getting damaged by a high-severity fire due to excess fuels accumulated from fire suppression. In addition, many culturally important plant species benefit greatly from fire. For example, California black oak has long been cultivated by native peoples to gather acorns. Fire can aid black oak stewardship by exposing bare mineral soil for acorns, encouraging basal sprouting of older trees, and keeping down acorn weevil populations that impact the acorn harvest.

Learn more about cultural resources and fire.

How do projects affect giant sequoias?

Fire suppression has severely limited sequoia regeneration and caused an unnatural and hazardous buildup of fuels. This combined with a warming climate have caused recent wildfires to severely impact these trees that were once thought to be impervious to fire. In 2020 and 2021 alone, wildfires killed 13-19% of all sequoias across their range. Park managers are seeking to conserve giant sequoia groves by implementing targeted mechanical thinning and prescribed fire.

Learn more about giant sequoia research.

How do projects affect the understory?

In response to fire, shrubs can aggressively resprout from their roots, and oaks can resprout both from the base and all along their trunks. Some plants, dubbed “fire-followers”, will start growing immediately due to lack of competition and increased nutrient availability; some even need heat or smoke to germinate. Short-term impacts to understory plants may occur due to heavy equipment and tree felling. However, plants will begin to regenerate as soon as a significant rainfall occurs. In some cases, replanting with native plant species is done to repopulate treated areas more quickly. Surveys and other measures are taken to avoid damage to rare plants and minimize soil disturbance during operations. Treatment areas are also monitored for invasive plant species and heavy equipment is inspected before entering the park to prevent introduction of non-native plants.

How do projects affect air quality?

Mechanical treatments can greatly reduce the potential for wildfire to spread and the volume of smoke that is produced. When planning prescribed burns, park managers estimate how much smoke will be produced based on the vegetation type, burn area, and weather conditions. In contrast to wildfires, prescribed burns are conducted only when prevailing winds minimize smoke dispersal into nearby communities. Air quality alerts are sent out before and during prescribed burn operations.

Learn more about current air quality and smoke monitoring and smoke in Yosemite.

How do projects affect water quality?

The projects occur at such a limited scale relative to watersheds that little to no impacts are expected. Even so, routine monitoring and a number of best practices are implemented to reduce the small potential for impacts. In many areas, stumps are ground down using heavy equipment and the woodchips are spread around to stabilize the soil and decompose more quickly. Slash and duff are also spread around to help mitigate erosion. Tracks in the ground are raked away to help with water flow. Where needed, removal of invasive plants and revegetation with native plants may also be done to repopulate treated areas more quickly and stabilize the soil.

How do projects affect visitors?

There may be short traffic delays or temporary road closures while crews are working along roads. These are scheduled during periods of low visitation when possible to minimize impacts to visitors. To protect the park’s soundscapes, all work that generates noise levels above 76 decibels near residential or visitor use areas are performed between 8 am and 5 pm. When crews are working, visitors are advised to keep a safe distance away, especially during heavy equipment operation and tree felling. Visitors sensitive to smoke should check for any active prescribed burn operations in the park and monitor air quality sensors to avoid impacted areas.

Scenic vista management improves the visitor experience by increasing accessibility to historic viewsheds and decreasing congestion and associated safety hazards at other scenic vista points. Hazard tree and biomass removal increase visitor safety by removing hazard trees and reducing wildfire risk.

Where are prescribed fires planned?

Prescribed fires are planned through 2028 in Yosemite Valley, Wawona, Yosemite West, the Mariposa Grove, the Merced Grove, Hodgdon, and Crane Flat. Interested parties should follow Yosemite’s fire social media to keep up to date.

Current fire information for Yosemite.

When was this fire?

• Big Meadow Fire (2009), burned near Foresta along Big Oak Flat Road.

• Rim Fire (2013), burned 10% of the park. Notable along Evergreen Road, Big Oak Flat Road from the entrance to the Merced Grove, and along Tioga Road from Crane Flat to White Wolf.

• Ferguson Fire (2018), notable in El Portal, Foresta, Yosemite West, and Wawona Road from the Rostrum to Wawona.

• Blue Jay Fire (2020), burned along Tioga Road east of White Wolf.

• Washburn Fire (2022), burned along Wawona Road from Studhorse Ridge to South Entrance and into the Mariposa Grove. Notably stopped due to previous prescribed burns and fuels reduction treatments.

Learn more:

• CalTopo Fire History Map

• Yosemite's fire history.

How are fires managed?

Fire is a natural and integral part of the park’s ecosystems, but this was not recognized by park managers until the 1970s. In the absence of fire, hazardous fuel loads have been allowed to accumulate and the plants and animals that have adapted to live with fire over millennia have suffered. The park now purposely sets fires under specific conditions to restore this vital process while still preserving public safety. Burning under these conditions meets multiple management objectives, including improving ecosystem health and reducing the risk of catastrophic wildfire. The park uses fire in three ways: 1) pile burns, 2) broadcast burns, and 3) managed wildfires. Pile burns and broadcast burns are planned ignitions and are methods of prescribed burning, while managed wildfires are unplanned ignitions.

1. Pile burning: fuels are cut and gathered into piles by hand or with heavy equipment. The piles are left to dry out, then burned under the appropriate conditions. Pile burning, while low risk, does not fully restore fire to the landscape as a natural process. Pile burning is often used in areas as preparation for broadcast burns or managed wildfires, or in areas where broadcast burns are not possible due to safety concerns.

2. Broadcast burning (also known as prescribed burning): fires are purposely lit and allowed to spread under specific conditions within a fixed area with defined objectives. Once an area is prepared, the weather is closely monitored until the temperature, relative humidity, windspeed/direction, and other environmental factors are within a predetermined range which best meets the restoration objectives. Broadcast burning most directly mimics traditional burning practices and addresses the negative effects of fire suppression, making it an effective tool for forest restoration.

3. Managed wildfires: unplanned ignitions from natural causes (i.e., lightning) are managed to achieve resource objectives. Wildfire management decisions are made on a case-by-case basis and are dependent on fire behavior, potential impacts to resources, weather conditions, air quality, potential threats to people and property, and other factors. If a wildfire is ignited by a person (excluding prescribed fire) or threatens life or property it is suppressed. Managed wildfire is a vital tool for restoration at larger spatial scales in remote wilderness areas.

Why doesn’t the park let all fires burn? Won’t forests be resilient and recover naturally?

In short, letting fires burn without thoughtful consideration of the outcomes ignores the complexities of the modern world. When conditions are right and all impacts have been considered, many fires in Yosemite are managed with minimal intervention. Yosemite has widely been considered a leader in the management of wilderness fires since the 1970s and has managed over 18,000 acres this way in 2021 and 2022 alone. The park carefully monitors the outcomes of these fires to inform future decision making.

Learn more:

• Fire ecology and monitoring in Yosemite

• Managing wildfire, prescribed fire, and fuels in Yosemite

How are projects affected by climate change?

Climate change in the Sierra Nevada is predicted to result in hotter drier summers, reduced snowpack, and more frequent severe drought. Declining water availability for the park’s dense forests along with higher temperatures and more expansive bark beetle attacks have already resulted in widespread tree mortality, most notably from California’s unprecedented 2012-2016 drought. Additionally, climate change has undoubtedly led to the increased frequency, severity, and size of wildfires in the Sierra Nevada. Fuels dry out earlier, creating a longer fire season. Hotter and drier conditions and fuels are dramatically intensifying fire behavior at night, which greatly increases the time when fires are active and impedes suppression tactics. While wildfires will undoubtedly continue to occur and threaten communities and ecosystems, we can still do our part. Fuels reduction treatments can be effective even in the face of severe fire weather, slowing the spread or reducing the intensity of a fire as it burns through the treated area. Small tree removal can also lessen drought-induced tree stress and mortality by removing competition with larger trees for water and other nutrients. If placed strategically and periodically maintained, fuels reduction treatments can help protect the places we value even in the face of climate change.

Learn more about climate change and fire.