– By Andrea Gaines
She feeds the birds. She shelters the mammal. She cools the air, provides us with shade and conserves the water and soil.
She is the mighty old oak, an ecosystem unto herself.
All except the smallest living things function as an ecosystem of sorts – whether harboring the bacteria and microscopic plants that break down organic matter, or sustaining the mammals, birds and other living things that draw nutrition and safety from them.
In the case of trees, and old oak trees in particular, the variety of life that they help sustain is enormous. The sturdy, slow-growing oak is an ecological champion – the great provider.
More than 100 vertebrate species, including deer, chipmunk, porcupine, rabbits, beavers, mice, black bear, squirrels, jays, ducks, pheasants, wild turkey and more browse on and cache – saving for future use – the oak’s leathery leaves, fatty, sugar- and vitamin-rich acorns, mineral-rich twigs, and nutritious young shoots. In the case of blue jays, the bird’s tendency to cache acorns in open fields gives the oak seedling a superior chance for survival, free of competition from neighboring trees.
Dozens of bird species, including chickadees, wrens, woodpeckers, flickers, owls, bluebirds and the jay use the mature oak’s branches, nesting holes, crown and crevices for shelter and to raise their young.
The oak’s acorns sustain whole populations of animals through the hardest of winters. For, while oaks are slow growing, they are long-lived and extremely productive. In a good year, a mature oak might produce 5,000 or more acorns.
Insects depend upon her, too. Mature oaks are used by more moth and butterfly species than any other tree. For example, eastern oaks support 20 species of dagger moths, 18 species of underwings, eight species of hairstreaks, 44 species of inchworms and 15 species of giant silk moths. The caterpillars of the emerald-green wonder known as the luna moth – one of the giant silk moths – are highly dependent on oak trees for nourishment.
Native Americans prized and revered the oak for its leaves, flowers, and bark, which they used for medicinal purposes. Tribes from the east coast to the west coast also used acorn flour in breads and stews, while tannins from oak bark were used for dying and tanning.
Many of America’s most enduring buildings are framed with the dense, durable wood of the oak tree.
And, a mature oak presides with great dignity over the spot in which it sits. The roots of an oak reach out to three times the height of the tree itself, stabilizing slopes, limiting soil and stream bank erosion, and providing for groundwater recharge. Mature oaks also trap carbon and other air pollutants, and cool the air around them by transpiring up to 100 gallons of water per day.
Food, shelter, water and soil conservator, the mighty oak is indeed the great provider.