Living amongst the oaks

What is more characteristic of the California landscape than the majestic oaks that dot our hillsides, fill our valleys and anoint the streambeds and arroyos of California?

There are over 22 specific species of Quercus (which is the botanical name for oak) in varied types of topography and climatic zones throughout this state. Within the oak family there are some trees that are totally clothed with leaves throughout the course of the year and there are those that go dormant and are deciduous, losing their leaves for a period of dormancy and rest.

The oak relatives of modern species contributed to the landscape of prehistoric California more than 20 million years ago. As the environment changed over time, so did oak habitats which support about 300 species of accompanying flora and fauna in their surroundings. Over the millennia, oaks have been sculptured by the features of their landscape, the leaves, the branches, their stout trunks and their expanding root-system that goes far beyond the drip line of the total canopy of the tree.

Each different species has developed distinct growth forms and tolerance to environmental stress, such as man’s impact when moving into their native woodland areas. In California today, the oaks are being threatened with today’s changing inner phase of the urban and wild lands that surrounds our communities throughout the state and elsewhere on this little planet.

But intensifying land use in the hardwood range has brought about soil erosion, reduced forage production, poor regeneration among some species of oaks and dwindling resources, due to development in their specialized plant community. The hardwood range of oak trees clearly shows signs of the last hundred years of human habitation around them.

The Southern California range of oaks has been in a drought cycle for some time now and oaks that are large consumers of water are now showing signs of stress due to the lack of normal annual rain perception.

All Californians can assist in the protection and enhancement of native oak resources, but none are in a better position to do so than landowners throughout the state with oaks on their property. These individuals shape the future by their decisions, which cumulatively direct the management and land use of more than six million acres in California.

Young native oaks are tolerant of environmental changes and will usually adapt to specialized landscaped practices. But as oaks mature, their environmental tolerances become set and changes can weaken or kill them in time. If the environment of an adult oak tree changes, like the introduction of summer watering for gardens, lawns, planter beds or improved pastures, fungi will proliferate on its susceptible roots and begin the decline of the most important structural component of any tree: the root zone.

As a landscape horticulturist, I see all too many times the wrong things going on around native mature oak trees that can eventually lead to various degrees of stress, decline and potential death of the trees.

Unfortunately, there may be few visible signs of a fungus attack before it is too late. I get too many phone calls asking me to come out and save their mature oak trees when the damage has been going on for some time. I refer to these calls as desperate eleventh hour calls and there’s usually not much I can do.

When I see people spend thousands upon thousands of dollars for a boxed (from the wilds) oak tree and install it into the landscape, they don’t seem to understand that the continued stewardship of that special tree is vital and ongoing if it is to become established and have a healthy future.

I have put together a listing of dos and don’ts in a flier and would be happy to pass this along for those of you who are concerned about the stewardship and health of native and introduced oaks into a landscape setting. To receive my informative horticultural flyer on oaks, please send a self-addressed stamped envelope to Roger Boddaert, PO Box 1806, Fallbrook, CA 92088.

Editor’s Note: Roger Boddaert is a certified arborist and professional landscape designer who serves on the board of directors of the California Oak Foundation.