In Praise Of Oaks

Jul 1, 2015

It is winter, the fog along the river heavy as sodden wool, the ramparts of Table Rock looming high above. I have to place my feet carefully on the rock-strewn slope, and when I raise my eyes, a great shape blocks my way, stretching gnarled hands out of the mist. I gasp, and a jay jeers in derisive laughter at my alarm, breaking the spell. What stands before me is no malignant giant, but an ancient lichen-shrouded oak, most benevolent of Oregon trees.

We now understand that the open oak savannahs and associated prairies filled with camas lilies were the product of regular fires set by the Kalapuya, Takelma, Shasta and other native peoples of Oregon.

In spring, this tree will be softened with a haze of new leaves and enlivened with warblers eagerly searching for the year’s first caterpillars. In summer, a pair of bluebirds will hurry to and fro with food for their growing nestlings, sheltered in the cavity of a broken limb. In autumn, the oak will wear a tawny cloak and its rich crop of acorns will attract swarms of jays, woodpeckers, and squirrels to its crown, while deer and turkeys gather at its feet.

When the first European settlers arrived in Oregon’s interior valleys – the Rogue, the Umpqua, the Willamette – they found rich prairies and park-like woodlands dominated by great oaks. They assumed they had discovered a natural paradise, little understanding that they were invading an ecosystem carefully managed for the production of acorns and other wild foods; or that the sophisticated managers were the native peoples they considered savages; or that the management tool was fire. 

Supplemental foods for native peoples included bulbs of the camas.
Credit Wikimedia Commons | Walter Siegmund

We now understand that the open oak savannahs and associated prairies filled with camas lilies were the product of regular fires set by the Kalapuya, Takelma, Shasta and other native peoples of Oregon. Large old oaks are resistant to low-intensity fires that kill the saplings of Douglas-fir and other conifers that would otherwise invade the savannahs. These oaks produced great quantities of acorns that were a staple food for the native people, as were the bulbs of camas lilies. Upslope from the valley bottoms, the foothills were a mosaic of oak groves, chaparral, and scattered pines, providing acorns, browse, and thermal cover for deer and habitat for many other wildlife species.

As everybody who has bitten into an acorn knows, they are not delicious straight off the tree. Acorns are high in bitter tannins, and were subjected to a complex process of shelling, grinding, leaching, and finally cooking with heated rocks in watertight baskets. The resulting mush or porridge was highly nutritious, rich in protein, carbohydrates, and fats.

Southwestern Oregon is the region of the state most blessed with oaks. Here we have all four of the state’s large oak species: the black oak, Oregon white oak, canyon live oak, and the tanoak (Notholithocarpus, an acorn-bearing close relative of the “true oaks,” genus Quercus). Of these, only the Oregon white oak extends farther north than the mid-Willamette Valley.

The diversity and abundance of our oaks is comparable to California, where a recent review concluded: “Oak woodlands have the richest wildlife species abundance of any habitat in California, with over 330 species of birds, mammals, reptiles, and amphibians depending on them at some stage in their life cycle …California oak woodlands rank among the top three habitat types in North America for bird richness. Oak woodlands are able to sustain such abundant wildlife primarily because they produce acorns, a high quality and frequently copious food supply… Oaks also provide important shelter in the form of cavities for nesting.”

The list of oak-associated species reads like a who’s-who of familiar “State of Jefferson” wildlife: deer, elk, bears, squirrels, jays, and woodpeckers eat acorns; kestrels, nuthatches, titmice, and bluebirds depend on cavity-rich oaks for nesting; and warblers, vireos, buntings, and finches feed and nest among their leaves. Perhaps the most remarkable of all our oak-dependent species is the Acorn Woodpecker. These noisy and conspicuous birds live in social groups year-round, and maintain “granary trees” whose thousands of holes are a storehouse for the acorns gathered and defended by the group. No acorns, no Acorn Woodpeckers.

Oregon has preserved only a tiny amount of lowland oak savannah and woodlands. The Oregon Department of Fish and Wildlife estimates that the Coast Ranges now retain less than 4% of their oak habitat, with about 7% remaining in the Willamette Valley. Numerical estimates for the Rogue Valley have not been made, but there is no question that most valley-floor and lower foothill oak woodland habitat has been highly modified or lost to agricultural and residential development. As a consequence of habitat loss and degradation, oak savannas in Washington, Oregon, and California have been designated as one of the 20 most threatened bird habitats in the United States by the American Bird Conservancy.

Fortunately, important oak habitats are protected in several preserves in southern Oregon, including the Table Rocks (jointly managed by The Nature Conservancy and BLM); Prescott Park on Roxy Ann Butte; the Cascade-Siskiyou National Monument, whose southern and eastern portions include much oak woodland; and a number of properties managed for conservation through the Southern Oregon Land Conservancy. However, there is much more that could be done, including expansion of the Cascade-Siskiyou National Monument into adjacent BLM lands with a diversity of oak habitats; and further support for preservation of private ranch lands when these become available for sale. If not preserved, these ranch lands – which provide much of our lower foothill “viewshed” – likely face subdivision and development, with loss of their scenic and wildlife habitat value. In an encouraging proof of what is possible, this spring a nearly 4800-acre ranch southeast of Ashland was purchased by a private conservation buyer, protecting an extraordinary expanse of oak savannahs and woodlands.

Oaks are the irreplaceable threads in the rich tapestry of habitats that stretch from our valley grasslands to the mountain forests. Here in southern Oregon and northern California, there is still time to preserve this fabric, but it will require our conscious effort and care. If we make that effort, our grandchildren will grow up as we have, their world held in the embrace of oaks, most benevolent of trees.

Pepper Trail is a naturalist and writer in Ashland, Oregon.