April 1998 // Volume 36 // Number 2 // Ideas at Work // 2IAW1

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Reestablishing Riparian Vegetation in Grazing Lands

Reestablishing Riparian Vegetation in Grazing Lands describes a research effort to successfully grow trees next to streams in former pasture land. Increased shade is evaluated by measuring light intensity. Techniques for preventing beaver damage are discussed. Efforts like this can alienate some landowners opposed to change, but can establish the Extension Service as an agency that can be part of the solution in sensitive natural resource issues.

Bill Rogers
Lincoln County Extension Agent
Oregon State University
Newport, Oregon
Internet address: william.rogers@orst.edu

Increased concern about dwindling numbers of coho salmon and steelhead trout has led to an interest in restoring riparian areas of coastal grazing land. However, a lack of research and practical experience in converting pasture to riparian vegetation has prevented landowners from knowing how to proceed. A cooperative effort was initiated to develop practical research- based information with the goal of improving fish habitat in the agricultural portions of coastal watersheds while removing as little pasture as possible from production.

The Beaver Creek watershed contains 31,000 acres on the central coast of Oregon. The water flows directly into the Pacific Ocean. Approximately 90 percent of the watershed is forested. About 2000 acres primarily adjacent to Beaver Creek are grazed by livestock; the remaining acreage is in coastal marshes and wetland. Nearly all shrubs and trees have been removed from the grazing land and livestock have generally unrestricted access to the creek.

The objectives of the Beaver Creek Riparian Project were: to control livestock access to the stream to prevent further deterioration of the stream bank; to plant riparian vegetation and allow natural plant regeneration to stabilize existing erosion problems within the livestock exclusion area; and to determine how effective varying widths of riparian tree plantings are at providing stream shading. Shading was selected as a qualitative measure of changes in stream temperature. Decreases in stream temperature are frequently associated with increases in shade.

Initial planning involved the district conservationist from the Natural Resource Conservation Service (NRCS), a forester from Oregon State University, and the local Extension agent. Funding was successfully obtained from the Governor's Watershed Enhancement Board (GWEB). The Lincoln Soil and Water Conservation District (LSWCD) agreed to handle the money and serve as co- sponsor. Additional funding was obtained from the Oregon Department of Fish and Wildlife (ODFW). Other sponsors providing labor for the project included the Mid Coast Watershed Council and the Angel Job Corps of the US Forest Service (USFS).


Two-thirds of a mile of one property owner's stream frontage was fenced on the south side of the creek only. Because of the depth of the creek bed and the steepness of the banks, cattle do not cross the creek at any point along this reach. After the grass was killed with herbicides, red alder seedlings were planted at a five foot spacing in one hundred foot strips of varying widths. Treatment units included strips that were one tree wide, three trees wide, and six trees wide. Each unit was repeated three times and included an unplanted strip as a control.

Light intensity data, as a measurement of shade, was collected in September 1995, 1996 and 1997. Data will continue to be collected each September for at least two more years.

Intensive beaver damage to the seedlings during the first summer required the application of beaver protection techniques including a repellent and several types of tree tubes.


Heavy grass regrowth stabilized the stream banks as soon as cattle were excluded. Most of this regrowth, however, was in the form of reed canary grass, an introduced species that grows so densely that native plants are excluded. This contrasted dramatically with the opposite, unfenced bank where cattle continued to graze to the water's edge and heavy soil erosion continued to occur.

Average tree height after three seasons of growth was 11 feet, with some trees reaching more than 18 feet. September 1997 light intensity measurements indicated an increase in shade throughout the planted area. Measurements will be collected for two more years before an analysis of the data is attempted.

Beaver damage continued to occur after trees were protected with the repellent and when Vexar tubes were used. However, three foot tall Protex growth tubes completely eliminated the damage. These translucent, solid walled plastic tubes come in a flat package. They are wrapped around the trees, then locked. The tubes require solid staking to hold up while the trees are young. They withstood major flooding and severe windstorms in each of the first two winters. The cost was fairly high at $1.14 for each tube and stake. (This does not include labor as volunteer labor was utilized.)

Information on progress was shared with landowners and other agency personnel at several on-site tours and through numerous presentations at local and statewide meetings.


Practical field research can yield results that may help landowners reestablish riparian shrubs and trees in grazing land. Where beaver are present, protection of woody vegetation is required. Involvement in projects such as this runs a risk of alienating some landowners who would prefer to see no change in land uses, but does establish the Extension Service as an agency that can help be part of the solution for a serious natural resource problem.