Impact of the 2017 Fires on Natural & Working Lands

In addition to the tragic loss of life, homes, businesses and public infrastructure, the 2017 Sonoma Complex fires burned natural and working landscapes including forests, shrublands, grasslands, rangelands and cultivated agriculture. These watershed lands are critical to the health of Sonoma County communities as they provide local food, filter our drinking water, protect cities and towns from flooding and landslides, sustain biological diversity, provide opportunities for the community to enjoy the outdoors, and contribute to the scenic beauty of Sonoma County. The soils, trees, and other vegetation in these watersheds sequester carbon, while the riparian corridors are critically important for climate change adaptation, wildlife movement and groundwater recharge.

Assessment of our Protected Lands

Approximately 7,000 acres of Ag + Open Space-protected land were directly affected by the 2017 fires. Following a wildfire of any size, the landscape changes, sometimes quite dramatically. While natural landscapes do recover on their own over time, some areas needed active restoration, management and investment of resources in order to avoid runoff of toxic materials and sediments into drinking water supplies and sensitive habitats, and to minimize the threat of flooding, landslides, and other hazards. Working landscapes may also need active restoration in order to re-establish crops or other agricultural uses.

In the wake of the 2017 fires, Ag + Open Space staff reached out to easement landowners in the burned areas to offer our support and share resources, and conducted visits to our own properties within and near the burned area, including Saddle Mountain, Calabazas Creek, Dogbane Preserve, and our properties along Mark West Creek.

Saddle Mountain Open Space Preserve was not burned and was not affected by fire suppression activities. The Preserve’s Management Plan, which was approved after these fires, incorporates planning and objectives relating to fuels management and fire preparedness, including targeted thinning of overcrowded forest stands, establishing shaded fuel breaks, and possibly prescribed burning. We also worked with outside consultants to complete road repairs that will help ensure that the main road through the Preserve remains accessible to emergency vehicles during future fires.

Dogbane Preserve was burned completely through the understory, removing all of the above-ground portions of the invasive Himalayan blackberry and Harding grass on the property. While the dogbane plants burned, the fire severity was relatively low and staff have since observed robust re-sprouting of these perennial plants as well as expansion of the plant population. The tree canopy was partially scorched, and trees may have been weakened, presenting an overhead hazard. Staff and volunteers have worked to control blackberries and Harding grass as they re-emerged, and continue to monitor the dogbane plants.

Calabazas Creek Open Space Preserve saw fire across the entirety of the property, but fortunately fire behavior was patchy and effects were generally very low to moderate in severity. The south-west-facing chaparral slopes in the western portion of the Preserve burned fairly hot, but this is a habitat that is well adapted to periodic fire. Since these fires, we’ve observed extensive, healthy re-sprouting of the shrub and hardwood species in this area. This habitat is also home to a species of manzanita that does not re-sprout but is dependent on fire to help its seeds germinate. We’ve been delighted to see thousands of new manzanita seedlings across these slopes. Most of the thatch burned off in the grasslands in the northern portion of the Preserve, which is a positive effect that should benefit this habitat, and the adjacent oaks got a bit scorched but appear to be recovering well. As expected, the fire stimulated aggressive germination of yellow star thistle in several of the Preserve’s grasslands and Ag + Open Space staff, contractors, and volunteers have continued to proactively manage this invasive species.

In the riparian zone along Calabazas Creek the fire left the forest canopy relatively intact but burned at low intensity through the understory, removing excess surface fuels as well as many Douglas fir saplings that had been encroaching into this mixed-hardwood forest. The fire resulted in many weakened and downed trees and a great deal of tree debris along the main Calabazas Creek trail. Professional arborists, Ag + Open Space staff and Cal Fire identified and removed nearly all the high and very high hazard trees (entire trees in imminent danger of falling).

The Mark West Creek properties (McCullough, Wendle, and Cresta) burned fairly hot, and Ag + Open Space staff and consultants made several site visits to assess fire severity and property hazards. The fire’s heaviest impacts were to the slope south of Mark West and Mill Creeks. Since the fires, oaks, madrones, and bay laurels have re-sprouted from their bases and the new growth is up to seven feet tall. Many of the conifers across this slope were coast redwoods and none appear to have been killed by the fire; all are re-sprouting extensively along their trunks and branches as well as from their bases. Many Douglas-fir trees were killed by the fire, but some of the largest overstory trees remain alive and green, and will likely rapidly repopulate this area after a period of dominance by hardwoods and redwood. Elsewhere on the properties, grasslands and oaks have put on lush new growth. There were areas on both properties where established stands of invasive Himalayan blackberry burned. Ag + Open Space has followed up with brush-cutting and spot treatments with a targeted herbicide application to prevent re-sprouting and re-establishment of these stands.

The Pelm house site along Mark West Creek at the McCullough property burned completely and was secured to prevent run-off over the rainy season. The remains have since been removed from site and disposed of appropriately. The site has been tested and cleared for hazardous materials and was seeded with a native seed blend prior to the 2018 rainy season, in order to further stabilize and restore the area. Nine plastic culverts burned, while the existing steel culverts survived intact. Ag + Open Space replaced several culverts, and provided funding to replace several more after the property was transferred to Sonoma County Regional Parks in November 2018.

On the Cresta property, the barns to the north of Porter Creek Road also burned completely. All the resulting debris have also been removed from site and disposed of. The burned plastic culverts along Cresta Road have been replaced with galvanized steel culverts.

Fire Disaster Recovery Work

Ag + Open Space staff worked on a number of fronts to respond to the impacts of the fires on our natural and working lands throughout the county. We:

  • Participated in a countywide Watershed Task Force with Calfire, CalOES, FEMA, County of Sonoma, Regional Parks, Transportation & Public Works, Sonoma County Water Agency, City of Santa Rosa, and City of Sonoma.
  • Contacted Ag + Open Space easement landowners and worked with UCCE to find available pasture land for grazing animals displaced by fire.
  • Engaged volunteers in invasive species control efforts in the spring and summer following the fires.