Preliminary results analyze Caples Burn’s ecological effects

2019 Caples Fire

Several years ago, the Eldorado National Forest’s Amador Ranger District determined that the Caples Creek watershed downstream of Caples Lake was a high priority for ecological restoration. The area is roadless, with beautiful stands of huge, legacy pines; old aspen groves; Caples Creek and the Silver Fork of the American River; lovely open meadows; and large granite shoulders. It’s popular for hiking, backpacking, hunting, and fishing, and much of the watershed is eligible for designation as a federally designated wilderness.

After more than a century of fire suppression, however, the watershed contained dense stands of small-diameter trees, excessive amounts of brush, and large amounts of surface and ladder fuel (branches, pine needles and the like). As a result, the watershed’s forest and meadows  areas were vulnerable to fire, drought, and bark beetle infestation.

Working with the community, especially Sierra Forest Legacy and the Eldorado Chapter of the California Native Plant Society, the Forest Service planned a series of prescribed fires to help restore the watershed to a more fire-resilient state. In Summer 2019, teams from the involved groups and the Forest Service thinned, removed and burned small trees and brush. They also raked deep layers of needles away from the legacy pines to prepare the area for a prescribed burn.

The prescribed burn began in late September. All was going well until the weather shifted after about a week. Then the situation changed, and high winds spread the fire to areas that had not been pretreated to reduce the fuel loads. The Forest Service declared the burn a wildfire on October 10 and brought in more personnel to contain and extinguish it. The fire was fully contained by October 25 after burning a total of 3,435 acres, more than three times the area included in the original plan.

Soon after the fire was extinguished, the Forest Service Fire Behavior Assessment Team began collecting data on the fire’s effects. The team compared pre-fire data for the portion of the fire that burned as planned with the post-fire results. However, pre-fire vegetation data was lacking for much of the remaining burned area. Using remote sensing data to analyze burn severity, the Forest Service scientists were able to make comparisons between portions of the area that had fuel treatments before burning and those that burned after the fire was declared a wildland fire.

The preliminary results analyzing the ecological effects of the 2019 Caples Fire were released by the Forest Service in May (https://acconsensus.org/wp-content/uploads/2020/05/05-Caples-Fire-Effects-2019-Report_11_May_2020.pdf?fbclid=IwAR2c7YZKJwycUL1QTBqZl9marcpr6mvWCcu9odoufdOdLKUTFZkViQRwkX4)

Key findings of the report include:

  • There were mostly positive ecological and fire resilience effects from both the prescribed fire and wildfire.
  • Overall burn severity was lower in areas intended for prescribed fire as opposed to fire that burned as wildfire. Some large diameter trees were scorched from the wildfire but the positive effects outweigh the loss. Much of the highest burn severity was in chaparral, not forest.
  • Average tree density was reduced, bringing densities closer to historical levels. Most of the trees killed by the fire were small-diameter trees, but some larger trees were also lost. The report states, “Areas burned with prescribed fire saw a 14% reduction of trees across all size classes, while areas burned as wildfire saw a 47% reduction.”
  • Raking around individual, large-diameter legacy trees in the area planned for burning greatly improved the trees’ chance of survival.

The Foothill Conservancy has long advocated for sound forest management that incorporates prescribed fire to achieve ecological resilience. While this prescribed fire did not go according to plan, we are largely encouraged by the results. We are confident that the Forest Service and its partners will learn from this experience and build on that knowledge for future prescribed fire planning.

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