Roger's Tree Pick for September: California oak

As a member of the California Oak Foundation and the San Diego Advisor, I bring to you one of California’s beloved trees: the mighty Quercus oak.

These majestic arbor giants are really one of California’s signature trees within the ecosystem of the native flora with 22 main oak species located throughout the state.

Unfortunately, we have lost more than 90 percent of the verdant stands of native oaks throughout California to date. Today our oak woodlands are being threatened by real estate encroachments, agricultural development, pathological fungi and myriads of new bugs attacking stressed trees within the pattern of our drought cycle which has been ongoing for decades.

Proper care for oak can ward off many of these problems and it’s all about understanding what makes them tick, good maintenance and proper stewardship.

Oaks drink a lot of water over the course of a year and some of the moisture is released into the atmosphere through small pores in the leaves. The pores allow carbon dioxide to enter the leaves and be converted into food through the process of photosynthesis. When faced with low soil moisture, the deciduous oaks can either keep their foliage and continue losing water through the leaf pores or drop their leaves and conserve moisture.

With the early shedding of green leaves, this can suspend photosynthesis and suppress acorn seed development. When this balance is upset and acorn production is reduced, the entire balance of the oak ecosystem goes awry.

It has been stated that there are more than 300 species of native flora and fauna that live and thrive in a natural oak woodland setting. This varied combination can include native grasses, salamanders, the under-story of assorted vegetation, woodpeckers, fungi, owls, blue jays, coyotes, ferns, mosses, lichens and a whole menagerie of bugs.

Within this fragile ecosystem, if bits and pieces become frail and start to lose connection with one another, the overall system starts to break down, and if these trees fail, the fire fuel load mounts up.

As a Certified Arborist with oaks as one of my specialties, I am called out to review many types of oaks in many types of conditions and I am always amazed how these grand trees are neglected. Oak tree planting is both a science and an art with proper installation and post maintenance of the wild collected oaks which could be three years or more.

A checkup every few years by a professional is advised to keep those trees and garden plants in a good state of health for your long-term enjoyment.

There are some other key points on managing oaks within a landscape setting. I wrote a paper called “Living Amongst the Oaks” some years ago; if you would like a copy and some additional oak information, send a stamped self-addressed envelope to PO Box 1806, Fallbrook, CA 92088.

Roger Boddaert, an International Society of Arboriculture Certified Arborist and a professional landscape designer and horticulturist, can be reached by phone at (760) 728-4297.

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