Site Characteristics and Scope
North of Enumclaw, Washington, a body of water named Beaver Lake (BL); nestled in-between Bass Lake and Sinkhole Lake comprises a rectangular area of 1/2 mile by 1/4mile. This site was acquired by King County from a logging interest which had cleared the landscape in 1999 of many conifers without replanting. King County partnered with the Green River Coalition (GRC) in the maintenance of the property which is predominately deciduous alder, big leaf maple and cherry with strips of mature conifers and a shrub layer largely of invasive Himalayan Blackberry. The site is well-drained with rolling topography. The Scope included a multi-year approach to weed suppression and planting of native conifers.
The invasive blackberry at this site was Himalayan blackberry and evergreen blackberry. This was organically removed without the use of any herbicides. The cane was cut at the base of the plant near ground level. When possible, the blackberry was pulled up from the root crown. If the cane is cut each season, before it has a chance to flower, then all of the plants energy goes into growing the cane instead of producing flowers. With the cane cut at the base close to the ground, the leaf surface area is also greatly reduced, thus decreasing the amount of energy the plant can produce through photosynthesis. This cutting method repeatedly starves the plant of needed nutrients and it eventually dies off. This method is derived from the experience and observation done by Green River Coalition and their interns. Furthermore, it has also been shown that the use of herbicides is not necessarily more effective than manual and mechanical removal (Soll, 2004). Although it involves more physical labor and time than using herbicides, this organic method of removal is preferred by GRC because it does not bring chemicals into the environment, which can be harmful to wildlife and native vegetation.
Many of the small saplings throughout this site were being crowded out by vegetation which was preventing them from getting any sunlight. Some of the vegetation were native tall grasses, as well as the invasive reed canary grass (Phalaris arundinaceae), some different types of blackberry, and native cleavers (Galium aparine). If an invasive species has been deemed Class C, such as Himalayan blackberry, then it is assumed to be impossible to eradicate completely. Management and control are the only options for a plant with Class C designation. Since sulfur cinquefoil is currently deemed a Class B Noxious Weed, and not yet widespread in the region, prevention of new infestations is a primary goal.
Through the stewardship of Green River College student interns, volunteers, and King County, several seasons of invasive plant removal have advanced the growth of conifer saplings, and restored sunlight to native plant understory. King County has provided a water tank truck to irrigate plants during summer drought. In general the site has shown modest native plant establishment in 5 years of restoration activities.