Healing the Land After the Fire
By The Sonoma Ecology Center
The devastating fires of October 2017 have created serious challenges for residents, many of whom are concerned about soil erosion, toxic runoff, and the health of fire-ravaged landscapes. Read on for insights and advice on these issues, presented by our staff of expert ecologists.
All residents, especially property owners and caretakers, are encouraged to follow the guidelines below in order to ensure the continued health of our beautiful county. By working together, we will rebuild – and make our home more healthy and sustainable than ever before.
The Post-Fire Landscape
Though at first sight a blackened landscape can look badly damaged, look again after the first rains. Native grasses and flowers thrive in a burned landscape, and will begin poking up as soon as the time is right. The truth is, wildfire can be ecologically beneficial to California landscapes, especially when it’s a cooler fire that burns through the understory (the layer of vegetation beneath the main canopy of a forest), leaving a black ash on the ground.
White ash, by contrast, indicates a very hot fire that may have killed the seed bank – but even hot fires don’t kill certain fire-adapted species.
In most cases, once man-made debris and ash are removed from a burn site, the land will heal itself in time. In many cases, and on most of any given property, the best thing to do will often be nothing.
Look for wildflowers to grow in great profusion for the next few years, including the “fire followers” that only appear after fire. Also watch for rare species such as spotted owls, which take advantage of burned landscapes.
Toxic Runoff
Although burned vegetation is non-toxic, burnt man-made structures leave behind toxins including sulfates, nitrates, asbestos, and heavy metals. This toxic ash can wash into our waterways during heavy rains, so keeping the ash and debris in place until it can be hauled away is a top priority.
Authorities are quickly following their procedure for removing toxic ash and debris from burned sites with structures and vehicles – let them do it. State agencies have mapped the likelihood of debris flow. Many agencies, nonprofits and residents are working quickly to contain and remove toxic ash and debris before heavy rains come.
Residents can help by using natural-fiber rolls called “wattles.” The wattles are staked to the ground, where they filter sediment and debris while letting water seep through. Wattles may be made of weed-free straw or coconut fiber called “coir,” and may be made with biochar or mushroom spores to increase uptake of toxics.
Wattles should be placed:
1) around burned structures and vehicles, containing the white ash area,
2) at the top of streambanks, even on small channels, and
3) around inlets of storm drains and road culverts.
Wattle effectiveness is directly tied to how level they are. As runoff water hits the wattle, it needs to go through the wattle, not along it. Use a level so that the wattle line follows the land’s contours.
Wattles are in high demand. More are being made available every day. If wattles are unavailable, use fallen branches, small berms, sandbags, check dams or staked boards – installed in the ways described above for wattles – in order to contain toxic ash.
Burned Tree Care
Even badly scarred native trees and large shrubs can recover over time, sometimes by re-sprouting at the base. Unless a blackened branch or tree would damage people or property if it fell, leave it in place until spring leaf-out, when it will be clear how much of it is dead. Meanwhile, even trees that are completely dead are still important as habitat, and their roots still hold soil in place and prevent erosion.
The University of California provides specifics on how to assess and respond to damage to burned oak trees.(Burned Oaks: Which Ones will Survive?)Consult with an arborist if you think a large tree poses a danger and must be removed. Otherwise leave them be.
Reseeding
Many residents feel the urge to reseed burned landscapes – but that’s not usually the best response! Sonoma County is a fire-adapted environment, and most native trees, shrubs and flowers will recover fully without our help. In fact, many need occasional fires to be healthy.
Still, there are some cases where careful reseeding is recommended.
Here are guidelines for knowing when and how reseeding should occur:
Sites where seeding might be needed tend to be sloped areas that burned very hot, leaving behind a white ash on the ground. Flat areas that burned at lower temperatures, leaving behind a black ash on the ground, generally do not need any seed or erosion control measures. If practical, a thin straw mulch will help hold soil in place (see above).
