For thousands of years the oak has been relied upon for a variety of uses, not only as a major food source, but wood for fire, utensils, and medicines. They are also critical habitat for a number of plant and animal species. Western Native American cultures actively managed their oak woodlands and savannahs in order to ensure the health of these trees for optimum acorn harvesting.
Understory burning was induced to prevent competition from other plant species, return critical nutrients to the soil, reduce insect pests, and prevent the build up of fuels.
Trees were kept pruned of damaged or diseased branches and used for firewood.
Without competition for water and nutrients, oaks were able to grow larger with full crowns that enabled more acorn production, a major source of food.
In addition to the oak itself, important compatible food crops could be encouraged to grow in the open areas between the oaks — such as indian celery (lomatum uriticlatim), as well as clovers and camas (camassia spp) in oak riparian areas. Many animal species, such as deer and elk also thrive in oak habitat.
Early management of oak woodlands, forests, and savannahs is often considered to be the first application of agroforestry practices.
Today, however, the value of oaks in that regard has virtually vanished and our oaks are plagued with numerous problems contributing to their severe decline.
Less than 10% of oak habitat remains in Oregon and their loss is being acutely noticed.
Lack of management has led to an assault by an ongoing litany of problems such as pest and disease cycles, competition from other species for water, nutrients and sunlight, invasion by over shadowing conifers, reduction in new trees, careless firewood harvesting, build up of fuels that increases fire damage, and ongoing development.
The infestation of acorns by weevils and filbert worms have infected acorns to the extent they are not viable for germination, ground squirrels, gophers, moles, and voles undermine sensitive root systems of emerging seedlings and saplings, and Sudden Oak Death (SOD) is taking out the larger oaks.
There are many native shrub species that serve as hosts to SOD. Limiting the growth of these species and allowing a more open environment could make it much more difficult for the disease to spread through oak habitat.
Conifers such as ponderosa pine and Douglas fir have become invaders into traditional oak habitat.
Their fast growth can quickly overtop the sun-loving oak and eventually kill them.
Oak habitats are home to a unique blend of plants and animal life that are not found in conifer forests, such as the streaked horned lark, the Western meadowlark, Lewis’ woodpecker, white-breasted nuthatch, western bluebird, acorn woodpecker, western gray squirrel, Columbian white-tailed deer, Fender’s blue butterfly, Taylor’s checkerspot butterfly, Kincaid’s lupine, and the Willamette daisy, among many other plant species depending on the region.
At least seven federally Endangered Species Act (ESA)-listed species are dependent on these habitats.
Oregon White Oak is also shade intolerant. The leaves are unable to efficiently photosynthesize nutrients without being exposed to full sunlight.
A restoration study was conducted at Fort Lewis Military Reservation in Washington State. It involved the elimination and reduction of overtopping conifers in oak stands.
Three levels of removal were evaluated: The first level involved complete removal of all Douglas fir, the second was remove all Douglas fir within one half of tree height, and the third involved the removal of just a few fir.
Within the first five years after treatment, the area in which all competing Douglas fir was removed resulted in renewed oak stem growth, increased acorn production, and enlargement of current branches for a noticeable increase in crown size.
What was surprising to researchers was the speed in which the oaks responded after years of suppression.
The increase in acorn production means more food for wildlife species dependent upon them and more available for oak regeneration. The formation of new branches indicated a return of health and vigor to the tree.
Humans have been a major factor in the decline of oak habitats and the plant and animal species that depend upon them. However, humans can also play the critical role of restoring them as well.
To this end, Wasco County SWCD and Area Watershed Councils intend to apply for a grant through the Oregon Watershed Enhancement Board’s Focused Investment Partnership Priority program initiative to assist landowners in implementing restoration of oak habitats.
This project will be in need of organizational partners to create a strategic plan and for implementation.
If organizations are interested in becoming a partner in this effort, please contact the Conservation District.
Together we can make a difference in the restoration of this critical habitat.
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