Project: “Year One Post-Fire Forest Monitoring and Evaluation Report for the Cascade Creek Property, Santa Cruz, California”
Spatial Informatics Group (SIG) has completed a post-fire monitoring report of a California redwood forest in the year following a wildfire—and results indicate reasons for optimism regarding the recovery of the trees.
The property provides an unusual opportunity to assess high-severity burning of redwood forest, a relatively rare phenomenon that is likely to become more common as wildfires become more frequent and intense.
The Cascade Creek Property, which hosts a mix of old-growth and second-growth redwoods, occupies 564 acres in the coastal hills north of Santa Cruz. The entire property burned at mixed severity in the CZU Lightning Complex fires, which were sparked by lightning and burned a total of 86,509 acres in August and September 2020. Several large patches exhibited high-severity burning effects, such as total or near-total top-kill of the overstory.
The Cascade Creek Property is owned by Save the Redwoods League, which acquired the land with the goal of creating continuous protected redwood habitat from the Santa Cruz Mountains to the Pacific Ocean. The nonprofit enlisted SIG to create a post-fire monitoring plan to quantify the fire’s effects and begin tracking recovery.
SIG established 25 representative tenth-acre plots across the property and collected detailed data both at ground level and from the air using drones. That study found that about 78% of the property burned at high severity.
Redwoods have the ability to resprout both from the base (basal sprouting) and the crown (epicormic sprouting), which offers even badly fire-damaged trees a path to recovery. In high-severity burn areas, 78% of redwoods showed basal sprouting and 61% showed epicormic sprouting in the year after the fire. Even in areas largely or entirely consumed by fire, survival rates are expected to be high because of resprouting. Larger redwood trees—those with a diameter greater than 30 inches—came through the fire best, with more than 90% of these trees expected to survive. This is likely because larger trees have thicker bark and therefore a higher capacity to protect the tree’s cambium from high temperatures.
The effort also assessed the fire’s potential impacts on the marbled murrelet, a coastal water bird that nests in old-growth redwoods. The high survival rates of large trees indicates that nesting habitat has not been severely diminished. It may take years, however, for the redwood canopies to recover through epicormic sprouting, so this issue will require continued monitoring.
The report concludes that the redwoods’ ability to resprout offers “optimistic signs for the future of these stands.” It recommends continued monitoring to track recovery trends, especially with regard to crown recovery and mortality of old-growth trees.
“This is one of the first times we’ve seen redwoods burn to this extent at this severity—but it probably won’t be the last,” says Shane Romsos, Service Area
Lead for SIG’s Natural Hazards Team. “What we learn here can help guide efforts to conserve these trees into the future.”