IN THE EASTERN crook of California lies the Eldorado National Forest, a sprawling wilderness characterized by a mix of conifers and vaulting elevations up to 10,000 feet. The area is beloved by backpackers, horseback riders and other recreationists, who steal out into the wilderness to catch the sweet vanilla scent of Jeffrey pines, the tug of brook trout on a fishing line and the rocky crags of the Sierra Nevada mountains.

In 2014, the King Fire ripped through the region, burning 97,000 acres over nearly a month. In about half of the area scorched by flames, 90% of the trees were destroyed. From the smolder emerged a partnership between American Forests and Eldorado National Forest that has sought to return resilient, climate-adapted forests to the King Fire scar.

In the past several decades, high-severity wildfires like the King Fire have become more common, permanently impacting landscapes by making it difficult for forests to regenerate on their own and creating conditions that can lead to a vicious cycle of repeat wildfires. “These are the areas that don’t come back as forests,” says Luis Vidal, American Forests’ Northern California reforestation manager. “If the forest can’t develop, the area grows into shrubland, making the landscape vulnerable to another high-severity fire. Hence, the need for us to come in.”

Since 2020, Vidal has been leading Eldorado National Forest and American Forests in developing shared stewardship strategies to prepare the site, plant new trees and use monitoring to inform future restoration. The partners have planted 1.1 million seedlings since 2017, 500,000 of them in 2022.

With climate change increasing periods of drought and contributing to conditions that spread pests and disease, innovative practices are necessary to create a new generation of trees that are resilient against environmental stressors. Vidal and his team have been implementing climate-smart reforestation strategies to support forest resiliency.

For example, they are using DNA testing to identify sugar pines immune to white pine blister rust, a fungus that is killing off swaths of trees. An estimated 3% to 5% of sugar pines are resistant to the disease, making them the ideal progenitors for healthy sugar pine stands. Following the guidance of the U.S. Forest Service, Vidal sends climbers high into trees to pluck fresh samples of needles that the Forest Service then sends out for genetic testing. The seeds from viable candidates are cultivated and subjected to one final test: exposure to white pine blister rust.

Parent trees of sugar pine seedlings that have passed muster serve as the stock from which seeds are collected to grow future generations. In August 2022, Vidal’s team collaborated with the Forest Service to collect 129 bushels of cones from trees with known resistance to white pine blister rust. The Forest Service will extract the seeds from their cones and nurture them in a greenhouse for future planting.

The team plants a hardy mix of drought-resilient native seedlings including sugar pine, Ponderosa pine, Douglas-fir, incense cedar, giant sequoia and Jeffrey pine. They have been experimenting with strategic spacing that imitates nature’s design of clustering and spacing trees. Using this technique, they planted approximately 200 acres of seedlings last spring.

Vidal’s team is monitoring the growth of this young forest, collecting more than 100 data points on variables like tree density, species composition and ground cover. Observations are being used to inform decisions about where to plant in 2023, as well as planting techniques to employ.

“As we continue to face the challenges of climate change, holistic strategy and innovation are going to be essential,” Vidal says. “We are thinking about the ecosystem as a whole and using a mix of best practices and experiments to inform our efforts to restore forests in California.