After the bad news coming out of the fires — deaths, destroyed homes, friends and clients suffering terrible losses, and swaths of forest burned — let me offer a perspective with respect to our trees and woodlands.
As an arborist, I have had many occasions to see the condition of landscape trees after fire damage. Since I began doing site visits here in 1992, I have seen many trees that were damaged and survived the Atlas Peak Fire of 1981.
Visiting properties on Atlas Peak and in Soda Canyon 11 or more years after that horrendous fire, I had no way of knowing how many trees were burned to the ground or damaged and removed, but evidence of an ability to withstand fire is evident in many large, surviving trees.
In particular, coast live oaks demonstrate this ability. Here is the pattern I have noticed: Where fire burns vegetation under the canopy of a mature live oak, it kills the undersides of the oak limbs. The response of the tree is visible, years later, where the exposed dead inner wood of the stem is partially enclosed in rolls of callus and woundwood at the margins.
One tree worker I know colorfully described it as “ a hot dog in a bun.”
Of course, that applies to substantial trees exposed to moderate fire.
In a paper on coast live oaks for the U.S. Department of Agriculture, Forest Service (See: https://www.fs.fed.us/database/feis/plants/tree/queagr/all.html#115) author Peter Steinberg includes a wealth of information on “Fire Ecology.”
He said, “Coast live oak is exceptionally fire resistant, more so than other California oak species. Adaptations to fire include evergreen leaves, thick bark and sprouting ability.”
He goes on to say, “Mature trees with live branches generally sprout from the branches. Trees with damaged branches sprout from the bole, which is better protected from fire by its thicker bark. Seedlings and saplings are generally top-killed, and sprout from the root crown after fire.”
In some cases, live oaks that look dead might still recover. A citation in the article states that large trees do not always sprout new growth in the first year after a fire. The authors recommend waiting at least one growing season, and possibly up to three years, to evaluate the survival of fire-damaged coast live oaks.
The article includes what I see as a hopeful note on the fire ecology of coast live oaks: Though invasive, Douglas firs are reduced by wildfires in oak woodlands, an increase in oak regeneration is favored because scrub jays prefer burned areas as acorn-caching sites.
In this “mast” year — major acorn crop year — there are loads of acorns, which will have survived in the areas that were not burned.
Sudden Oak Death workshop
The workshop on Sudden Oak Death (SOD) is still on schedule. It will be presented in Napa by the University of California Forest Pathology and Mycology Laboratory on Saturday, Oct. 28, 10:30 a.m. at the Napa County Public Library, 580 Coombs St., Napa.
Volunteers in Napa participated with the UC Lab in the SOD Blitz effort for the seventh consecutive year.
The lab released results of this year’s Blitz on Friday, Oct. 13. Viewing the map and summary of the results at www.sodblitz.org, I noted good news for Napa County. We had a very low infection rate.
Dr. Matteo Garbelotto, director of the UC Berkeley Lab, will discuss the Blitz results and provide practical information including:
— How to assess the risk of your trees becoming infected.
— How to recognize the symptoms in oaks and in plants that carry the disease.
— How and when to apply the material that has proven to be effective in preventing infection, both by the trunk spray method and the trunk injection method.
— Managing California bay laurel trees, the most significant carriers of the disease.
— Potential effects of wildfire on SOD.
I will be there too, to introduce Dr. Garbelotto and answer questions on the Napa Blitz effort.
The session is free and open to the public. Pre-registration is not required.