Invasive and noxious plant species are common impediments to management objectives in the Planning Area. Invasive species are, for the most part, nonnative species whose introduction into an environment where they did not evolve causes, or is likely to cause, economic or ecological harm. These species make efficient use of local natural resources difficult and often interfere with achieving management objectives for the site. Noxious species are species designated by federal, state (state of Wyoming Noxious Weed List), or county government (Weed Control Districts) as injurious to public health (Tables 3–24 and 3–25). Although noxious weeds are almost always nonnative, this RMP and EIS makes a distinction because noxious weeds can include undesirable native plants. A pest can be any biological life form that poses a threat to human or ecological health and welfare.

The CYFO and WFO control invasive species on BLM-administered lands through cooperative agreements with the Big Horn County, Hot Springs County, Park County, and Washakie County Weed and Pest Control Districts. In addition to the county weed and pest control districts, both field offices work in cooperation with the Wyoming Game and Fish Department (WGFD), State Lands Division, State Parks, local NRCS offices, and private landowners. Invasive species are an increasing problem in the Planning Area and are affecting water and other resources.

In 2004, there was an invasive species inventory of 40 percent of the Bighorn Basin. Based on the results of this inventory, it was estimated that there were approximately 60,000 acres infested with invasive species (BLM 2008c). There are an ever-expanding number of acres infested, especially with Russian knapweed, leafy spurge, perennial pepperweed, Russian olive, and Tamarisk along the Bighorn River and its tributaries. Additional new weed species such as cheatgrass are beginning to appear in other locations in the Bighorn Basin.

The BLM manages noxious and invasive weeds in the Planning Area pursuant to BLM goals described in Partners Against Weeds, An Action Plan for the Bureau of Land Management (BLM 1996). These goals include prevention and detection; education and awareness; inventory; planning; integrated weed management; coordination; and monitoring, evaluation, research and technology transfer.

There has been an increase in weed occurrences in developed oil and gas fields, along roads and pipelines, and on public lands with increasing recreational use. The shrub component of the plant community often takes decades or more to establish, and even longer to reestablish after disturbance. Many reclamation efforts performed 20 or more years ago still do not have shrubs established and have not achieved reestablishment of wildlife habitat comparable to that before disturbances.

Two invasive species of special concern are Russian olive and Tamarisk, which deplete water and are replacing cottonwood and willow. Work has begun on controlling the two species; however, observations indicate that these invasive species are spreading within the boundaries of the Planning Area (BLM 2009b).

In 2007, the WFO estimated that approximately 57,000 acres in the field office were infested with nonnative annual bromes (primarily cheatgrass and Japanese brome). These bromes appear to be invading grassland, sagebrush grassland, mixed grass prairie, desert shrub, and mountain shrub community types. Inventory information is available for only about 10 percent of the Bighorn Basin, so actual infested acreage might vary.

Both the CYFO and WFO are targeting plants that are designated on the state of Wyoming Noxious Weed List or declared on the county noxious weed lists (refer to Tables 3-24 and 3-25). The primary species targeted on public lands include cheatgrass, Russian knapweed, spotted knapweed, diffuse knapweed, leafy spurge, Dalmatian toadflax, Canada thistle, scotch thistle, musk thistle, houndstongue, hoary cress (whitetop), field bindweed, puncture vine, Russian olive, and Tamarisk. These plants are typically found in sagebrush/grassland, desert shrub, and riparian/wetland community types. The present goal is to contain and reduce densities of invasive species populations. Table 3-26 lists the number of acres of each species the BLM treats in the Planning Area.

The CYFO and WFO treat approximately 2,500 acres of invasive-species-infested areas annually. The BLM endeavors to acquire more inventory and monitoring data, but there still is not enough available data to determine the actual trends in invasive species establishment. Based on observations and reports from Weed and Pest Control Districts, treatment efforts appear to be keeping invasive plant species populations from continued rapid spread, but are not necessarily reducing existing populations.

Cooperative Management in Invasive Species and Pest Control

The BLM manages noxious and invasive weeds in the Planning Area pursuant to BLM goals described in Partners Against Weeds, An Action Plan for the Bureau of Land Management (BLM 1996). These goals include prevention and detection; education and awareness; inventory; planning; integrated weed management; coordination; and monitoring, evaluation, research and technology transfer.

The BLM adheres to the concept of integrated pest management, or the use of a wide range of available tools and techniques to meet management objectives in site-specific situations. Vegetation treatments, including those for noxious weeds on public lands, are currently implemented under the principles and methodology outlined in IM No. 2008-030 (BLM 2007c), and instruction for implementing the ROD for the National Vegetation Treatments Final Programmatic EIS (BLM 2007a). In addition, IM WY-2009-022, Wyoming BLM Reclamation Policy (BLM 2009l), identifies 10 reclamation requirements, of which managing invasive plants is one, which must be addressed when developing reclamation proposals for all surface-disturbing activities.

The BLM manages invasive species in the Planning Area in nine weed management areas and two Coordinated Resource Management areas for weeds. Most of the species the BLM targets for management have not invaded BLM-administered lands in the Planning Area; however, invasive species that have invaded BLM-administered lands are expanding their range (BLM 2009b). The goal is to contain and reduce densities of known invasive species populations.

Pest Management

In February 2003, the USDA Animal and Plant Health Inspection Service (APHIS) and the BLM signed an MOU detailing cooperative efforts to suppress grasshoppers and Mormon crickets on BLM-administered lands (APHIS AND BLM 2003). This MOU clarifies that APHIS will prepare and issue to the public site-specific environmental documents that evaluate potential impacts associated with proposed measures to suppress economically damaging grasshopper and Mormon cricket populations. The BLM must also approve a Pesticide Use Proposal (Form FS-2100-2) for APHIS to treat infestations. APHIS would begin treatments after environmental review and BLM approval of the Pesticide Use Proposal.

Wyoming-designated pests under Wyoming Statute 11-5-102(a) (xii) include grasshoppers, Mormon crickets, prairie dogs, ground squirrels, mountain bark beetle, and beet leafhopper. The preferred method for treating grasshoppers and Mormon crickets is by Reduced Agent Area Treatments (RAAT). RAATs are a grasshopper suppression method in which the rate of insecticide is reduced from conventional levels, and treated swaths are alternated with swaths that are not directly treated. The RAAT strategy relies on the effects of an insecticide to suppress grasshoppers within treated areas while conserving grasshopper predators and parasites in areas not directly treated.

Fish and Wildlife Resources

The BLM is responsible for managing fisheries and wildlife habitats, and state and federal wildlife management agencies oversee BLM management activities. Fisheries habitat includes perennial and intermittent streams, lakes, and reservoirs that support fish through at least a portion of the year. See Section 3.1.4 Water for a description of drainages in the Planning Area that provide fisheries habitat, including the Bighorn River, Wind River, Clarks Fork of the Yellowstone River, and their associated tributaries, including the Nowood, Greybull and Shoshone rivers systems (Map 3). Aquatic habitat varies by vegetation type, water quality and quantity, land use, and landscape setting within these drainages and their tributaries. The U.S. Fish and Wildlife Service (USFWS) provides regulatory oversight for all species listed, proposed for listing, or candidates for listing under the ESA (see the Special Status Species section in this chapter). The USFWS also administers the Migratory Bird Treaty Act, which protects migratory bird species whether they are hunted (as with waterfowl) or not (as with songbirds).