Forests are a dynamic force on Earth. On a planetary level, they help regulate temperature and climate. On a local level, they protect watersheds and support biodiversity. Both levels are critical to human well-being, however, the megafires decimating millions of trees yearly in the Sierra Nevada tell us our forest is in trouble and so are we.

Fortunately, there are science-based solutions for reducing catastrophic fire to help the forest become resilient to the challenges it faces from a warming atmosphere. Tested locally, these solutions need to be rolled out at scale– 25 million acres in the Sierra Nevada need treatment. At scale, projects require a common understanding of forest ecological history so that the public supports goals for forest health and human safety.

Our forest was born in the wake of receding glaciers at the end of the last Ice Age, about 13,000 years ago, at the time people appeared. Humans are a dynamic force and are fire workers. They observed that abundance sprang up in the path of fires set by lightning strikes. To renew the plant-life relied on for food and materials, they began to care for the forest with small fires.

This practice created an open forest ecology with a patchy, multi-age, stand structure anchored by large, shade-intolerant, fire-adapted trees. The understory was rich in biodiversity and supported by a vast, symbiotic mycorrhizal fungi network under the soil of equal volume and complexity. The entire ecology evolved with human set, low-intensity fires.

One hundred and seventy years ago indigenous people, the Washoe in the Tahoe Truckee region, were brutally usurped. Thousands of years of intimate knowledge of the forest habitat were lost in the transition to settler influence over the forest. The new people didn’t value forest ecology, but they did value the large trees economically. The Tahoe Basin was clear-cut to build. Fire was suppressed ruthlessly to protect timber resources that were foundational to industrial wealth.

Without fire regulating growth and selecting for fire-adapted species, forest seedlings grew back very densely. Stands are uniform in age and dominated by shade-tolerant and fire-intolerant species. Duff piles deeply, preventing snow melt and water from reaching the soil. Volatile fuel loads build up. We became so adept at suppressing fire, that people felt safe moving into the forest. Biodiversity plummeted.

As the atmosphere warms, insect hordes invade from the South feasting on trees too parched to produce the sap needed to fend them off. Mega-fires decimate the forest, badly degrading air quality, and the watersheds that provide 60% of the fresh water for 40 million Californians. In spite of this, economics continued to drive forest management policy and clear-cutting was common until environmental organizations slowed the practice on public lands through legal challenges.

It could be said that the prolonged stalemate between these interests had one overarching benefit. It gave scientists across the West, like those leading The Sagehen Forest Project at UC Berkeley– Sagehen Creek Field Station in the Tahoe National Forest, a window of time to better understand the forest ecology and to collaborate with forest stakeholders. Together they forged a forest management policy focused on forest health. It benefits all ecological, economic, and social constituents.

Essentially, to halt catastrophic fire, improve air quality and protect watersheds, we need to reintroduce indigenous practices in caring for the forest, restoring it to a state that tolerates regular treatment with low-intensity fire. Restoring an open, multi-age, forest stand structure with an ecology anchored by large, fire-tolerant trees will be helpful. At scale, restoration includes three stages. First, a census of forest species, flora, and fauna, by scientists who then choose which smaller trees are removed to reduce fuel loads. Secondly, removal of chosen trees. Thirdly, returning low-intensity fire to the forest floor at regular intervals through prescribed burning by managed fire crews.

Forest collaborator’s recommendations are being incorporated into California state and federal management policies. Both state and federal agencies recognize the threat to forests, air quality and watersheds and are shifting considerable funding into restoration. Even so, saving our forest has many challenges. Fortunately, humans and the forest are both dynamic forces, capable of responding to threats. However, only humans can respond quickly. To find out more about these issues, visit the FOREST⇌FIRE interpretive exhibit at the new Truckee Community Recreation Center through June.

Heather Llewellyn is co-creator, with her partner Michael Llewellyn, of The FOREST⇌FIRE Project. In addition to their environmental and social practice, she enjoys reading, road trips and riding her ancient Schwinn cruiser whenever and wherever she can