Klickitat River Landscape Level Oak Habitat Restoration
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Klickitat County in the eastern Columbia Gorge contains some of the most extensive oak woodlands and savannas in Washington State. This dry landscape of steep canyons contains highly valuable habitat for many species of wildlife including the state listed Western gray squirrel. Other at-risk species include the California mountain kingsnake and Lewis woodpecker and acorn woodpecker. It has some of the highest breeding populations of Lewis woodpecker in the Pacific Northwest, and is also the northern most location of an active nesting colony of acorn woodpeckers. Unlike many remnant oak sites in the Willamette Valley, the oak woodlands in this area often have relatively intact understories, dominated by native species. |
The Columbia Land Trust has received two grants from the Washington State Salmon Recovery Funding Board to acquire 880 acres along the Klickitat River. Along with the long-term goals of improving riparian function for native salmonid populations, a major focus of management is to enhance upland oak habitats and reduce fire risk.
As a precursor to developing a restoration and management plan, existing conditions were thoroughly documented. This assessment included botanical and wildlife surveys, and a forest and road inventory. A network of 170 permanent GPS referenced vegetation sampling and digital photo points were installed and data collected on trees, understory vegetation, noxious weeds, snags, and down wood. The above information was used to produce a baseline of natural resources on the property.
A landscape design of desired future vegetation conditions was developed after considering wildlife habitat needs of focal species, fire effects, historic conditions, and management constraints and opportunities presented by individual sites. Potential ecological effects of wildfire were considered by modeling how fires might behave under current vegetation conditions and weather typical during summer months. While historic conditions (1800s) were used as a blueprint for restoration, the final desired future conditions overlay was modified from this “reference condition” by maintaining a higher tree density for a number of reasons. 1) Most sites were inaccessible to equipment, so all biomass removed would have to be piled and burned. Reducing tree density to a historic level would cause excessive soil impacts. 2) Given steep slopes on much of the ownership, management tools to maintain desired open grass/forb dominated understory was limited. Increase of shrub vigor and dominance with lower residual tree was expected. Therefore desired tree density was adjusted to account for understory plant community and its anticipated response to light and disturbance. 3) Response of older oak trees is unknown, especially on these low productivity sites. Thus, benefits of thinning in terms of improving vigor of remaining trees need to be assessed before stand density is reduced to reference conditions. 4) Western gray squirrels appear to benefit from a denser mixed tree species condition than was thought to occur historically. The effects of thinning to different tree densities on eastern populations of this species are unknown. Therefore, a conservative approach was taken whereby areas around nest trees were thinned to reduce “ladder fuels” and fire hazard while retaining Douglas-fir, ponderosa pine and a higher density of oaks than in other areas (see below). In summary, restorative prescriptions across the ownership were designed as a compromise between the desire to increase tree vigor and reduce fire risk while minimizing burn pile impacts, managing light levels to understory, and maintaining habitat for focal species.
In the summer of 2004 “mosaic thinning” (an approach whereby retained trees are variably distributed) was applied on 130 acres using a combination of hand falling and piling, and mechanical sheering using the Lightfoot. The Lightfoot is a small rubber tracked machine that allows low impact tree harvesting and brush reduction. As part of this treatment, an experimental thinning approach was implemented around identified western gray squirrel nests. This thinning prescription reduced fuels and fire risk, released oak and pine from competition with neighboring trees while maintaining aerial “escape corridors” radiating out from nest trees. Down wood levels were increased by leaving coarse woodpiles, while fine fuels (“kindling” sized pieces) which contribute to high intensity fire behavior were reduced. Treatments in 2004 are the initial steps in a multi-year plan to restore mature oak structure, native understory cover, and reduce fire danger on Columbia Land Trust properties within the Klickitat drainage. Subsequent treatments will include prescribed burning, use of goats, native grass seeding, herbicide control of noxious grasses and re-establishment of native bunchgrasses. Monitoring will include repeat photography and remeasurement of permanent inventory plots. Burn piles will be monitored for noxious weeds. Follow up squirrel surveys are also planned. Thinning treatments were made possible by a grant secured by the Forest Restoration Partnership, an Oregon-based non-profit 501(c)(3) organization founded to promote the conservation and restoration of declining forest habitats in the Western United States. Additional funding was provided through Columbia Land Trust by the Wildlife Forever Foundation. Columbia Land Trust is a private, non-profit land conservancy working along the lower 200 miles of the Columbia River in both Oregon and Washington. To date, the Land Trust has conserved more than 6,500 acres benefiting fish, wildlife and communities within the region. Expansion of treatments to adjoined lands owned by Washington Parks, Department of Natural Resources and private landowners is being pursued. For further information on this project contact: Ian Sinks,Columbia Land Trust
isinks@columbialandtrust.org
Darin Stringer,
Forest Restoration Partnership
darin@forestpartners.org