Oak: The Frame of Civilization & Oaks in the Urban Landscape: Selection, Care, and Preservation

Oak: The Frame of Civilization
William Bryant Logan, 2003. WW Norton & Company, 5 x 8 inches, 336 pages, $15.95 (paper)

Oaks in the Urban Landscape: Selection, Care, and Preservation
Laurence Costello, Bruce W Hagen, and Katherine S Jones, 2011. University of California, Agriculture and Natural Resources, 8.5 x 11 inches, 265 pages, $55 (paper)

I’ve been a lover of oaks since my childhood years in Michigan. My library contains a number of cherished books about oaks, including Glenn Keator’s wonderfully informative and beautifully illustrated The Life of an Oak (Heyday, 1998). On a recent airport layover, I chanced upon William Bryant Logan’s Oak: The Frame of Civilization. Totally engaging, Logan’s book provided an unexpected background to Oaks in the Urban Landscape, which appeared on my desk shortly after I had finished Oak. The two books could not be more different, but both address the tremendous importance of oaks in our lives, our cultures, our world.

Raised in the oak woodlands of Northern California, Logan is a highly regarded arborist on the East Coast today. He is also a passionate observer and chronicler of the natural world around him, as evidenced by both Oak and his previous book, Dirt: The Ecstatic Skin of the Earth. In Oak, Logan plays the storyteller as he traces the history of the genus Quercus and its relationship to civilization.

Oaks, it turns out, have played a surprisingly influential role in allowing human societies to flourish. Where oaks were common, the earliest hunter-gatherers congregated. There, they found food, shelter, bark for clothing and footwear, wood for fire and construction, and eventually materials for tanning, medicines, and even ink for some of the earliest written communication. A distribution map of the world’s oak species would show that concentrated populations of oaks coincided with the earliest human populations centers.

In The Ohlone Way: Indian Life in the San Francisco-Monterey Bay Area (Heyday, 1978), Malcolm Margolin noted that the densest population of Native Americans was in Northern and Central California, due in great measure to the prevalence of a diversity of oaks, which, in turn, provided food from acorns and from the various forms of wildlife that were attracted to the oak woodlands.

The California Indians did not, however, build grand structures of oak, in part because they had no need to in so relatively benign a climate. For that, Logan looks to the early Europeans, who built great churches and meeting halls and sturdy sailing ships of oak, often using the natural branching structure of the trees to guide the design of building or ship. Logan clearly is fascinated with this aspect of oak’s contribution to civilization and devotes a major portion of his book to stories of the evolution of architecture and naval architecture, including more than I ever thought I would read about the history of naval combat on the high seas.

For most of us today, oaks are simply the grandest of trees around us. Neither the tallest species, nor the heftiest, oaks are nevertheless the trees with the greatest presence in almost any landscape. Some of North America’s most iconic images are of craggy bur oaks studding Midwestern plains, of moss-draped live oaks shading streets in the Deep South, of wildflower-filled Garry oak meadows in the Pacific Northwest, and of dark green, gumdrop-shaped oaks and golden grasses in California’s extensive oak savannas.

Oaks face a number of challenges when the urban world enters their world, as it has done and is continuing to do, most problematically in the West. Acknowledging this trend, Laurence Costello and Katherine Jones, both with the University of California Cooperative Extension, joined with colleague Bruce Hagen, of the California Department of Forestry and Fire Prevention, to co-author Oaks in the Urban Landscape. The result is a tremendous resource for arborists, urban foresters, horticulturists, landscape architects and planners, maintenance contractors, Master Gardeners, and homeowners. There is no other book that gives such a full story of the selection, care, and preservation of oaks in the urban landscape.

An opening chapter reviews the native oaks of California, including both tree and shrub species, along with a number of oak species from elsewhere in North America and around the world. The descriptions and photographs provide a superb guide for the identification of four-dozen species of oaks that may be found in Western landscapes.

To fully appreciate the care and preservation needs of a tree demands a thorough understanding of its structure and growth pattern. Here, the authors look at the whole tree but devote a significant section of their book to the underground story of an oak—its root systems and the soils in which it grows. This is of particular importance, we learn, because the roots of many of the West’s native oaks, keenly adapted to our dry summers, are particularly sensitive to changes in the hydrology of their soils; an increase in moisture during the warm season will often foster the growth of various soil pathogens (Armillaria and Phytophthora, in particular) that can result in sure death for the trees. A sidebar by Michael Allen, from UC Riverside, further explores the mycorrhizal relationships that allow oaks to capitalize on and contribute to the underground world in which they grow.

Much of the text describing the cultural practices for maintaining oaks in the landscape may seem academic to the average homeowner. To compensate, numerous sidebars provide information in a nutshell for the less academically inclined. One particular sidebar by Bob Perry, landscape architect from Cal Poly Pomona and author of the outstanding Landscape Plants for California Gardens (reviewed here in July 2010), summarizes beautifully the considerations involved in designing around existing oaks and in designing landscapes to include new plantings of oaks.

Oaks provide habitat for an astonishing diversity of wildlife forms, from nearly invisible microorganisms, to the countless insects that feed upon their leaves and bark, to the birds and rodents that relish their acorns and find homes among their boughs. Some of these organisms may prove to be pests, especially in the urban environment, nibbling away at the foliage or drilling into the bark. A chapter on Biotic and Abiotic Disorders brings attention to those organisms, as well as various diseases and environmental factors that may affect the health of an oak. Of particular value is the six-page Diagnostic Guide, a sort of key to the problems that befall oaks, which directs the reader to a full description of each disorder and its recommended treatments, when they are warranted.

Fire is always a concern in the West, particularly in the urban wildland interface. Oaks are among the most adapted of native trees to fire in their ecology, generally surviving, and sometimes benefiting, from all but the most severe firestorms. The authors include a thorough discussion of the risks to oaks in the face of fire and the need to establish a defensible space around structures in an oak-dominated landscape.

The concluding section focuses our attention on the preservation of existing oaks in the developing landscape. Acknowledging the substantial benefits that oaks add to a landscape, this may be one of the most important sections in this book, which should be a part of every garden professional’s resource library.

Richard G Turner Jr, editor