Vegetation Resources

Impacts Common to All Alternatives

This section describes potential impacts to all vegetation types (Map 29) under all alternatives. The sections that follow describe potential impacts to individual vegetation resources (i.e., forests and woodlands, grasslands and shrublands, or riparian/wetland resources).

There would be surface disturbance under all alternatives, and all alternatives apply BMPs for surface-disturbing activities. Surface disturbance directly affects plant communities through vegetation removal and mechanical damage to plants. Indirect impacts to vegetation from surface disturbance on vegetation include soil compaction, alteration of soil horizons, erosion, changes in hydrology, and invasive species encroachment. These indirect impacts would limit recovery or rehabilitation of vegetation communities following disturbance. Conversely, vegetation treatments (e.g., mechanical treatments, fire), while involving short-term disturbance, would result in long-term beneficial impacts to vegetation communities. Vegetation treatments would pursue objectives to increase species and structural diversity, control invasive species, improve the quality and quantity of vegetation for wildlife and livestock, restore habitat connectivity, and create or maintain the desired vegetation structure.

Depending on the air quality conditions in the area at the time of proposed treatments, the BLM may implement restrictions on prescribed burns and vegetation treatments in forests and woodlands to maintain air quality. Planning and timing restrictions on vegetation treatments to minimize emissions associated with fugitive dust or smoke would result in short-term adverse impacts to forests, woodlands, and forest products.

Development of facilities and infrastructure associated with transportation networks, minerals, and recreation would increase habitat fragmentation in the Planning Area, could remove vegetation, and contribute to the introduction and the spread of invasive species. ROWs concentrated in a corridor tend to localize or confine disturbance to a smaller area and reduce disturbance in areas identified as sensitive.

Renewable energy development, especially in the form of wind turbines, could result in adverse impacts by fragmenting vegetation communities and requiring mechanized maintenance that has the potential to make these communities more vulnerable to invasive species establishment and wildfire. However, there are no current or pending ROW authorizations for wind facilities in the Planning Area. The limited projected surface disturbance from these activities would have a minimal impact on vegetation.

Recreation use in vegetation communities could result in indirect short-term adverse impacts from unplanned ignitions and unauthorized woodcutting in forestlands in and adjacent to campgrounds, and degradation of vegetation along trails and roads. Unless properly designed and managed, the development of recreation trails, both motorized and nonmotorized, could erode soils, which would cause adverse impacts to vegetation communities. Increased development of nonmotorized and motorized trails and trailheads can increase recreational use and associated impacts to vegetation communities (e.g., the potential spread and establishment of invasive species and risk of unplanned ignitions) over time. Adverse impacts would generally be more intense from roads and trails that allow motorized vehicle use.

Using the Wyoming Standards for Healthy Rangelands (Appendix N) to determine the minimum acceptable conditions for public rangelands would improve the health and diversity of vegetation communities. Impacts to vegetation from livestock grazing management on BLM-administered lands include the removal of forage by livestock, which may alter the amount, condition, composition, and vigor of vegetation. Grazing during the growing season or summer months may reduce the vigor of desired species and change in species composition. Livestock concentration around supplemental minerals or water would disturb soil, remove vegetation, and alter plant community composition.

Livestock and, to a lesser extent, wild horses and wildlife would contribute to the introduction and spread of invasive species, including noxious weeds. Livestock, wild horses, and wildlife may transport seeds of invasive species into the Planning Area (Bartuszevige and Endress 2008). Areas where animals concentrate and disturb the soil would be particularly vulnerable to infestations of invasive species. Range improvements that disturb the soil surface would provide locations for invasive species to become established. Heavy grazing of native vegetation may increase the susceptibility of an area to invasive species infestation. However, livestock grazing management that promotes healthy ecosystem function would create conditions more resistant to the spread of invasive species.

The BLM anticipates that potential impacts from VRM classifications, soil and water resources, air quality, invasive species, NHTs and other historic trails, transportation, wildlife, and special status species would influence the location, size, and shape of vegetation treatments and restrict the location and construction of access roads for activities such as forest and woodland treatments.

Summary of Impacts by Alternative

Certain types of management that restrict surface-disturbing activities and other resource uses would generally protect vegetation communities. Table 4–8 provides an overview of select protective management actions by alternative for each plant community in the Planning Area. The purpose of this table is to provide a broad overview comparison of the alternatives. The proceeding sections further discuss the effects of these and other management actions for each plant community.

¹Includes only lands designated as Wild Lands.

Source: USGS 2008c;BLM 2009a