Wednesday, May 19, 2010


My home of Prescott, Arizona is a really interesting place. At over a mile high and sporting a hodge-podge of geological features, including at least two extinct volcanoes, mountains and numerous outcroppings of granite boulders, Prescott hosts a number of very different environs. We have Prescott National Forest, a conifer forest comprised mostly of towering ponderosa pines which often reach over a hundred feet tall. We have grasslands that sport herds of pronghorn sometimes a hundred strong. In low areas and around creeks we have lush riparian areas that are home to cottonwood trees that are often more than ten feet wide at the base. Granite Dells is a couple of square miles of bare granite boulders. But one of the most interesting and unique is the chaparral.

Chaparral is dry, scrubby landscape. Trees are more prevalent than on the plains, but certainly not prevalent enough to call it a forest. The most common trees are juniper, pinion pine and various species of oak. Elderly specimens of these trees sometimes reach 30 feet high, but most are shorter than 15 feet. The ground sports a little grass and a few forbs and cactus, but is mostly bare dirt. The most prevalent vegetation in the area is the brush. The chaparral sports a number of tough, woody bushes that often form an impenetrable barrier. Manzanita is the most beautiful, with smooth, glossy, mahogany colored bark. Mountain mahogany and three-leaf sumac with their sour berries are also common. The dominant bush, though, at least in my area, is the scrub oak.

I have always found scrub oak a terribly interesting species. Well, there are actually several species of scrub oak. I grew up back east and am accustomed to the towering, majestic oak trees back there. While scrub oak is certainly a member of the Quercus family, it is virtually unrecognizable as an oak compared to its loftier cousins. About the only familiar feature is the acorns. Instead of deep green, lobed leaves, they have small, gray, thorny leaves. Instead of a single majestic trunk, most bushes have multiple stems that rarely get over a few inches in diameter. A few of the older specimens will grow multiple trunks that get about 10’ high and 4” in diameter. As I mentioned before, there are many different species of oaks native to this area and I am still learning about them. Some grow into something that is clearly a tree while some stay as bushes less than 4’ tall. And, of course, there is everything in between.

As someone who engineers with biology, I am particularly fascinated by the number and biomass of oaks in the chaparral, and most of that biomass is in the form of sticks less that 1” in diameter. Chaparral is also really prone to fires, and oak burns hot. So the local scrub oak is adapted to periodically having all of its above ground vegetation burned off without dying. So you can completely cut the top off of a scrub oak and it’ll just grow back. They grow massive root balls underground and are well adapted to living in really adverse conditions.

As anyone who has tried to grow mushrooms has probably noticed, nearly all of the culinary mushrooms readily available really like to grow on oak. While the chaparral looks really unforgiving to most, I just see all that available oak. To me it just looks like an endless, sustainable source of food. My neighborhood has about 8.5 acres of mostly undisturbed chaparral, with 7.5 acres in one chunk just outside my back door. Some areas of this are unreachable and impassable due to the density of brush. If I harvest just a tiny percentage of this, I could chip it up and keep producing healthy, delicious mushrooms for the rest of my life, all without significantly impacting the scrub oaks.

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