Walking with a property owner through a burned woodland area adjacent to a vineyard last week, a couple of interesting things came up.
First, he expressed concern that areas of standing, blackened trees and shrubs look like charcoal that could be fuel for another wildfire. “Shouldn’t this all be cleared out?”
It was one of those questions that make you pause and think.
My general recommendation for partially burned trees that are not apparently hazardous is to wait and see what they do this summer before making decisions for pruning or removal. So, what if they constitute a fire hazard in the mean time?
Looking into it as best I could — I am not a forester or wildfire expert — I checked a few resources, spoke with staff at the Napa Resource Conservation District (RCD) and came up with these points:
- Looking at the WERT reports (State of California Watershed Emergency Response Team) for the Nuns Fire and the Atlas Fire, general recommendations do not address any risk of blackened trees and shrubs igniting again. In contrast, there is great concern for erosion and debris flows.
- As pointed out by the RCD staff, burned stems are a beneficial source of carbon, which is important for soil fertility, soil structure and other factors. There are reasons not to remove it.
- The most flammable components have already burned off. As stated in “Introduction to the Chaparral” (Biological Sciences, Santa Barbara City College): “Chaparral shrubs are very flammable due to the resinous foliage, woody stems, accumulated litter, and standing dead branches. Flammability of chaparral species increases over time through deposition of flammable leaf litter impregnated with volatile oil (oils in the leaves help make the plant drought resistant).”
Going a little further, consider how charcoal is made. Wood is heated with a carefully limited amount of oxygen. There is no such control in a wildfire. It stands to reason that woody stems burned in open air are poor-quality charcoal. They are like the blackened remnants you clean out of your fireplace.
All of this supports the “wait-and-see” approach to assessing burned trees and shrubs.
The other item of interest was something new to me. After recent rainfall, as we walked along, on moist soil under the canopy of burned trees, I noticed swaths of small, orange dots.
I figured it could not be a moss or other green plant. It is not, well, green.
I took a photo and sent it to a mycologist friend, Stephanie Jarvis, who quickly responded.
“Oh yes. It is very common in burn areas. It’s an indicator that the environment is recovering. The common name is orange peel fungus… very easy to identify.”
She sent a photograph and reference naming it: Aleuria aurantia. The little orange dots expand into flattish and partially curled, orange mushrooms.
The aftermath of the wildfires has a positive side. Where the burning was not too severe some of the singed trees sprouted new growth in autumn, and there are signs of life in the soil after some good rainfall.
The learning experience will continue. By midsummer, we will have a much better idea as to the condition of singed and partially burned trees. Then we can make better informed decisions for care.