OAR 629-643-0000: Vegetation Retention Goals for Streams; Desired Future Conditions

(1) The purpose of this rule is to describe the vegetation retention measures for streams, the measures’ purposes, and how the measures shall be implemented. The vegetation retention requirements for streams, as described in OAR 629-643-0100 through 629-643-0500, are designed to produce desired future conditions for the wide range of stand types, channel conditions, and disturbance regimes that exist in Oregon’s forestlands. (2) The desired future condition for streamside areas that require forested buffers is to grow and retain vegetation so that, over time, average conditions across the landscape become similar to the conditions of mature streamside stands. Oregon has a tremendous diversity of forest tree species and stand density along waters of the state. The age of mature streamside stands varies by tree species. Mature stands generally occur between 80 and 200 years of stand age. Hardwood stands and some conifer stands may become mature at an earlier age. Mature forests provide ample shade over the channel, an abundance of large wood in the channel, channel-influencing root masses along the edge of the high-water level, and regular inputs of nutrients through litter fall. Mature forests are generally composed of multi-aged trees of appropriate and varied density, native tree species well suited to the site, a mature understory, snags, and downed wood. (3) For the forests specified in (2) above, the rule standards for desired future conditions and located in Western Oregon or the inner zone in Eastern Oregon can be developed by using normal conifer yield tables for the average upland stand consistent with the geographic region to estimate the conifer basal area for average unmanaged mature streamside stands (at age 120). For site specific vegetation retention prescriptions basal area targets, see the table in OAR 629-643-0400. These rule standards provide guidance for operators to implement site specific alternate plans to develop site specific vegetation prescriptions, described in OAR 629-643-0400. (4) The desired future condition for streamside areas that do not require tree retention areas, as defined in OAR 629-643-0130, is to have sufficient streamside vegetation to support the functions and processes important to downstream fish use waters and domestic water use, and to provide habitat for amphibians and other wildlife across the landscape. Such functions and processes include but are not limited to: (a) Maintaining downstream cool water temperature and other water quality parameters; (b) Influencing sediment production; (c) Stabilizing banks; and (d) Contributing nutrients and organic matter. (5) In many cases, the operator may achieve the desired future condition for streams by applying the standard vegetation retention and small forestland owner minimum option prescriptions as described in OAR 629-643-0100, 629-643-0105, 629-643-0120, 629-643-0125, 629-643-0130, 629-643-0135, 629-643-0141, 629-643-0142, 629-643-0143, and 629-643-0145. In other cases, the existing streamside vegetation may not be able to develop into the desired future condition in a timely manner. In these cases, the operator may apply an alternative vegetation retention prescription as described in OAR 629-643-0300 or develop a site-specific vegetation retention prescription as described in OAR 629-643-0400. For the purposes of these water protection rules, "in a timely manner" means that the trees within the riparian management area will substantially move towards the desired future condition more quickly than if the trees are left untreated.