and Environmental Consequences Roadless Area Conservation FEIS Inventoried roadless areas support a diversity of aquatic habitats and communities. Without the disturbances caused by roads and associated activities, stream channel characteristics, such as channel and floodplain configuration, substrate embeddedness, riparian condition, amount and distribution of woody debris, stream flows, and temperature regime, are less likely to be altered (Furniss and others 1991). Illegal introduction and harvest of fish species are also less likely to occur in these areas due to lack of ready access. Inventoried roadless areas are home to many native species of terrestrial and aquatic plants including rare, TES species. Many have narrow geographical ranges determined by soil types, climatic conditions, or other environmental factors. These endemic species, due to their natural, limited distribution, are often at a relatively high risk of extinction from human activities or other causes. Areas in the United States with considerable numbers of endemic plant species include California, Texas, Alaska, the Pacific Northwest, the Southwest, the Intermountain West, and the South (Gentry 1986). Invasion of nonnative species into North American is one of the most important issues in natural resource management today, with more than 6,000 species originating outside the United States. The ability of these species to alter native populations, communities, and ecosystem structure and function is well documented (Elton 1958; Mooney and Drake 1986; Vitousek and others 1987; Drake and others 1989). The ability of managers to eliminate invasive species, once established, is often limited. Since roads provide an entry way for nonnative species, inventoried roadless areas can act as strongholds against invasion of these species. The following sections provide a detailed discussion of the potential effects of the prohibition alternatives on biodiversity: Any other indirect and cumulative effects as well as any effects of the social and economic mitigation for all environments under Biodiversity are discussed at the end of this section. Ecoregions Affected Environment The distribution of plants and animals is strongly influenced by physical environmental gradients (Whittaker 1967). These gradients are generally specified by solar radiation, thermal, moisture, nutrient, and biotic regimes (Nix 1982). These gradients are Roadless Area Conservation FEIS Environmental Consequences overlapping and result in areas where ecological communities, dynamics, and inherent capabilities are distinct from neighboring areas. These areas have been defined as ecologically defined ecoregions. Ecoregions broadly describe key environmental variables across the United States, including: physiography, geology, soils, hydrology, climate, land use, vegetation, and wildlife. Figure 3-26 summarizes the ecoregion classification used in this "coarse" scale analysis (Omernik 1995; Gallant and others 1995). Ricketts and others (1999) provide detailed descriptions of the biodiversity of each ecoregion. Table 3-26 shows inventoried roadless acreage by ecoregion and protected status for ecoregions greater than 100,000 acres. Globally outstanding ecoregions (Ricketts and others 1999) are shaded and in italics. Alternative 1 - No Action Forty-five of the 83 ecoregions in the 'lower 48' and Alaska have more than 100,000 acres of NFS land that contain inventoried roadless areas. Of these, 35 ecoregions have more than 12% of their area managed to protect natural values, such as Wilderness or inventoried roadless areas. These 35 ecoregions make up about 70% of the NFS land base. Sixteen ecoregions that contain more than 100,000 acres of NFS lands in the continental United States have been assigned a status of globally outstanding (Ricketts and other 1999). Globally outstanding ecoregions are biologically distinct based on species richness, degree of species endemism, and rarity. Less than 8% of the acreage in the globally outstanding ecoregions is now protected in the East, which is well below the 25% to 75% recommendations of Noss and Cooperrider (1994) and the 12% World Commission on Environment and Development (1987) (Figure 3-26 showing boundaries of ecoregions in the East). Eighty-three percent of the ecoregions in the West already exceed the 12% protection threshold and 56% exceed the 25% threshold. All of the globally outstanding ecoregions in the West and Alaska already exceed the 12% protection levels, and most (81%) exceed the 25% protection level. Alternative 2 This alternative would greatly improve the protection of ecoregions from road construction and associated human disturbances within the NFS; more than doubling the ecoregion area protected in inventoried roadless areas in 11 of the 45 ecoregions (Table 3-27). The largest acreage increases would occur in Alaska, the Sierra Nevada, and the Klamath-Siskiyou regions of California. Under this alternative, most of the ecoregions on NFS lands would exceed the 12% protection threshold suggested by the World Commission on Environment and Development (1987). Sixty-four percent of the ecoregions would exceed the minimum protection threshold of 25%, and 5 ecoregions would exceed the upper limit of 75% protection suggested by Noss and Cooperrider (1994). *Those species with restricted geographical ranges determined by soil types, climate, and other environmental factors. and Environmental Consequences Roadless Area Conservation FEIS While many of the ecoregions in the United States are not considered globally outstanding, several changes that would result from this alternative are noteworthy. Nationally, 5% or less of Okanogan Forests, Eastern Cascade Forests, Montana Valley and Foothill Grasslands, and Northwest Mixed Grasslands ecoregions are protected in special designated areas. This alternative would more than double the area protected in these ecoregions. In addition, protected acreage would more than double in 13 ecoregions (Table 3-27), which currently protect between 5% and 25% of their area. Under this alternative, the Chihuahuan Deserts and Central Pacific Coast (Coastal Washington and Oregon) have the smallest area protected of all the globally outstanding ecoregions in the West. The largest percentage increase in the West occurs in the Northwest Mixed Grasslands, Wyoming Basin, Montana Valley and Foothill Grasslands, and Okanogan forest ecoregions. Table 3-27 shows the increased protection for ecoregions resulting from this alternative. The table only includes ecoregions greater than 100,000 acres of NFS lands. Globally outstanding ecoregions (Ricketts and others 1999) are shaded. Since relatively few acres are protected in the East, even small increases are important. Under this alternative, four Eastern ecoregions in the national forests would exceed the 12% threshold of protection (Table 3-26). Two areas, the New England/Acadian Forests and the Northern Tall Grasslands, would exceed the 25% threshold. The largest acreage increase would occur in the Ozark Mountains and Mixed Mesophytic ecoregions (Table 3-27). Alternatives 3 and 4 Under these alternatives, the effects on the area of ecoregions protected from road construction and reconstruction would be the same as under Alternative 2. Fragmentation Affected Environment Fragmentation, in this analysis, refers to human activities dividing large areas of forest into smaller tracts separated by different landscape elements. Examples are common in urban areas and forest landscapes where clearcutting was used extensively. (The Tongass National Forest effects analysis includes a discussion of natural and humancaused fragmentation.) As human-caused fragmentation increases, the amount of unaltered central or core habitat decreases, which increases adverse edge effects (see Terrestrial Wildlife section), including increase in human activity, changes in microclimate (Chen and others 1995; Concannon 1995), increase in human-caused fires, and invasion of nonnative species (Saunders and others 1991; Skole and Tucer 1993). |