Presented by the University of California’s Division of Agriculture and Natural Resources, the 8th California Oak Symposium was intended for anyone involved in research, education, management, and conservation of California’s oak woodlands. This includes foresters, range managers, tribes, arborists, landowners, community groups, land trusts and policy makers.
Preserve Ecologist, Michelle Halbur, presented some of the exciting research happening at Pepperwood at theCalifornia Oak Symposium held in San Luis Obispo in early November. Cory O’Gorman, former grad student at Sonoma State and Pepperwood Visiting Scholar, also presented on his collaborative research conducted at the reserve and in cooperation with Pepperwood’s Native Advisory Council, which focused on black oaks through the lenses of culture and ecology. It’s wonderful to see these projects representing the reserve and helping to connect ecologists, academics, and ranchers alike to exciting work throughout California.
Pepperwood’s Research Team authored a publication for the Symposium entitled Post-fire Recovery in the Understory: Woody Fuels Management and Restoration in Oak Forests at Pepperwood
ABSTRACT: Following severe wildfire, land managers are often faced with forest conditions that require intensive management in the understory, such as controlling plant invasions or addressing the perpetuation of woody fuel loads in the forest understory from falling trees and limbs. Here, we present our forest monitoring data and observations of post-wildfire recovery at Pepperwood, a 1,294-hectare (3,200-acre) nature reserve in eastern Sonoma County, that was burned in October 2017 and 2019 by the Tubbs and Kincade Fires, respectively. In areas managed for Douglas-fir (Pseudotsuga menziesii var. menziesii) incursion, we detected a significant reduction of litter and duff depths after the Tubbs Fire; mean duff depths remained below pre-fire levels for all sample years, whereas there was an accumulation of litter two-years post-fire, likely due to fire-induced canopy die off. For downed woody debris fuels, there was no significant effect of year on the mean fuel load. However, when broken down by lag time fuel type, all classes exhibited reductions in fuel loads except for 1000-hour sound fuels, which were sustained by falling trees post-fire. To deal with tree mortality in the canopy and the accumulation of understory slash from wildfires, we thinned a subset of oak forest in preparation for pile and broadcast burning starting in 2020. These post-wildfire thinning practices increased fuel loads in some areas to levels greater than we documented prior to the Tubbs Fire in managed areas, posing a high fire hazard risk. To reduce excessive slash on the forest floor, we selectively conducted over 2,000 pile burns starting in winter 2020, resulting in localized areas of high burn intensity. As we continue pile burning, we are restoring the burn areas by planting native perennial grasses collected and propagated on-site. Our restoration goal is to suppress invasive weed establishment and to encourage the forest understory to recover to a native perennial grass and forb dominated system. We are also considering modifications to our thinning practices, such as thinning in phases, to enhance the feasibility of broadcast burning and reduce the risk of high severity wildfire.