Mitigation Mitigation measures designed to protect wetland areas involve, to the extent practicable, the avoidance of wetlands. The use of BMPs in both construction and maintenance ensures that flow, circulation patterns, and chemical and biological characteristics of the wetland's water would be minimally impaired. Implementation of these procedures is required to maintain the physical and chemical functions of wetlands (EPA, 1993; USDA Forest Service, 1995). Cumulative Effects Cumulative effects on wetlands would be proportional to the level of harvest and road building that occurred. The cumulative effects of harvest to forested wetlands is anticipated to be minimal. Overall, 655 acres (approximately 2.4 percent) of wetlands within these watersheds have been harvested over the last 100 years and 59 acres (0.14 percent) have been roaded. Due to these low percentage rates, and the relatively low acreage of wetlands affected by the proposed alternatives, significant cumulative effects to wetland resources are not anticipated. Additionally, revegetation of forested wetland sites generally occurs in the same time frame as other forested sites, usually within 3 to 5 years. Consequently, long-term effects to forested wetlands are expected to be minor. Since growth rates on forested wetlands are expected to be lower than on non-wetland forest sites, merchantable timber from these acreages may not be available under a 100year rotation. New road construction on wetland sites would use culverts to minimize disruption of water flow and permeable subgrade materials to avoid restricting the natural movement of water. These measures would ensure that the hydrological, chemical, and biological functions of wetlands would be minimally impaired. The roadbed overlying wetlands will remove the area from production. Road storage and restoring the drainage for the temporary roads would reduce potential sediment deposition to wetland sites within this area. Stormproofing roads left open by providing drivable water bars/rolling dips and gating all new roads would slightly reduce the potential sedimentation of wetland sites due to road use. Skipping Cow Timber Sale Final EIS April 2000 181 Resources Affected Environment The Project Area contains approximately 25,740 acres. Approximately 1,192 acres have been harvested, of which approximately 763 acres are considered managed stands. The remaining harvested areas are in the beach fringe or other currently unsuitable areas. Based on recent field exams, approximately 2,654 acres of the approximately 7,116 acres of tentatively suitable land with mature timber could be harvested using conventional road and cable systems. The Vegetation Resource Report lists the estimated acres and volumes by cable yarding setting. This 2,654 acre area has an estimated volume of 64.1 MMBF of timber. The remaining area appears to be limited to helicopter access (approximately 4,462 acres with an estimated volume of 91.9 MMBF). Approximately 2,634 acres of the suitable land limited to helicopter access is more than 0.75 mile from a road or a potential road. Figure 3-13 shows the average classification for the Project Area. Figure 3-14 shows suitable timber. Ecological Characteristics-Commercial Five commercial tree species are present in the Project Area: western hemlock, mountain hemlock, yellow-cedar, western redcedar, and Sitka spruce. Each species possesses certain characteristics that determine its location and abundance on the landscape. Each species forms plant communities or plant associations with other trees, shrubs, and forbs. The species composition of a plant association reflects the soil, climate, and disturbance history of a site. Species composition estimates for stands being considered for harvest in the proposed alternatives are displayed in Table 3-32. These species are described in the Vegetation and Timber Resource Report (USDA Forest Service, 1998i). Table 3-32 Species Composition of Stands Being Considered for Harvest Western |