I’m often asked whether the fire mimicry techniques that have been so successful in oak restoration work on other trees. Given that many California native tree species are fire-adapted there is every reason to believe that fire mimicry could help them too. Indeed, I have several previous posts showing positive responses of a variety of non-oak species to fire mimicry treatments, including buckeyes, redwoods, and Douglas firs.
Today I would like to share some recent results with pine trees. California pines are also fire-adapted, and with the suppression of forest fires, are becoming ill and infected with bark beetles and pitch pine canker. Thus, fire mimicry treatments seem to be critical in helping sick pines and in keeping healthy pines from deteriorating.
The four-year results shown below are of a sick Monterey pine in Carmel, the two-year results are of mostly healthy ponderosa pines in Glen Ellen, and the one-year results are of mostly healthy Monterey pines in Mill Valley.
A word about the four-year results. I first treated this Monterey pine in 2008 when the owners observed some decline in the tree. On my return the following year I found the pine to have deteriorated slightly. By the second year it had deteriorated significantly. I was mystified since the nearby oaks I had treated were responding nicely. Pines have an extensive root system, so I decided to peek over the neighbor’s fence and was surprised to find the entire yard was a Japanese garden with a mat of mosses forming a solid carpet on the ground. While mosses serve a purpose in a Japanese garden by stunting growth, creating twisted forms, and stimulating unusual foliage coloration in the small trees and acid-tolerant shrubs, a heavy moss cover is not compatible with a nearby large, fast-growing pine.
I was able to get permission from the neighbor to treat the soils, but I could not spread minerals on the soils as that would likely damage much of the moss cover, thus, ruining the aesthetics of their garden. So, instead, I did a deep root feeding by drilling small holes through the moss mat and injecting the minerals into the subsoil. These treatments were done in 2010 and again in 2011. The photos below show that after two years the pine has made a nice recovery.