Various surface-disturbing activities, including mineral exploration and development and the associated roads, ROWs, and corridors, can directly affect habitats for BLM special status plant species. Recreational use, collection of plants, fire, as well as livestock, wild horse, and native ungulate grazing may remove or trample vegetation and disturb soil, resulting in adverse impacts to BLM special status plant species. Surface-disturbing activities also can indirectly affect BLM special status plant species by contributing to soil erosion and transporting invasive species into BLM special status plant species habitats. The spread of invasive species could adversely affect BLM special status plants due to the limited size and distribution of these sensitive plants. Surface disturbance also can result in habitat fragmentation, which can isolate populations of BLM special status plant species. Populations of BLM special status plant species typically have a patchy distribution across the landscape, and eliminating one or more populations can prevent gene flow among populations if residual populations are too far apart for sufficient cross-pollination. Habitat fragmentation would be a long-term impact to BLM special status plant species. Implementing the Wyoming Mitigation Guidelines for Surface-disturbing and Disruptive Activities (Appendix H) and the Wyoming BLM Reclamation Policy (BLM 2009l) minimizes adverse impacts from surface disturbance.
Several BLM special status plant species (e.g., Shoshonea, Absaroka beardstongue, Evert’s waferparsnip, Wyoming tansymustard, limber pine, whitebark pine) occur in inaccessible areas, rugged terrain, or on unstable slopes in the Planning Area. As a result, there are fewer threats to these species and the anticipated adverse impacts from surface-disturbing activities are minimal. Management actions that restrict surface disturbance on unstable slopes would result in beneficial impacts to these species. For BLM special status plant species in riparian/wetland areas (e.g., Ute ladies’-tresses, persistent sepal yellowcress), management actions that limit activity in these areas are anticipated to benefit these species by reducing direct impacts from trampling, mining, and recreational activities. Meeting PFC across all alternatives improves habitat for Ute ladies’-tresses and persistent sepal yellowcress.
Livestock grazing may result in both adverse and beneficial impacts to BLM special status plants depending on grazing intensity, timing/season of grazing, range conditions, and precipitation regimes. Livestock grazing may maintain or create habitat for BLM special status plant species by reducing competition. However, livestock grazing may result in direct mortality through trampling, herbivory, and general site degradation (e.g., soil compaction, erosion). Livestock grazing in areas of Ute ladies’-tresses could benefit this BLM special status plant species as long as grazing occurs outside the flowering period. Adverse impacts to Williams’ spring-parsley and Hyattville milkvetch from livestock grazing are not anticipated, as cattle and sheep are not known to graze on these plants. Under all alternatives, adherence to Wyoming Standards for Healthy Rangelands (Appendix N) would help to limit impacts to BLM special status plant species. Potential adverse impacts from wild horse grazing would be limited to HMAs and would be similar under all alternatives as the initial appropriate management level for the HMAs would remain the same.
Travel and transportation management may adversely affect BLM special status plant species if motorized travel is allowed in areas with these species. Motorized vehicle use disturbs soil and removes vegetation resulting in adverse impacts to BLM special status species plant habitat. The generation of dust from motorized vehicle travel on roads next to BLM special status plant species could affect plant development, growth, reproduction and overall population survival if there are only a few individual plants in the area. Invasive species are more likely to spread along trails and roads and may out compete BLM special status plant species.
Management in special designations (e.g., ACECs) ultimately protects special status plant species by avoiding or prohibiting surface-disturbing activities in these areas. These designations may increase the interest, popularity, and use of these areas, resulting in increased potential for disturbance and removal of BLM special status plant species and the spread of invasive species.
Some management actions generally benefit all BLM special status plant species. For example, management to control invasive species may benefit BLM special status plants by reducing competition for available habitat. Management actions that protect erosive soils, riparian areas, and steep slopes are beneficial to most BLM special status plant species. Beneficial impacts are anticipated for BLM special status plant species where protection of visual and cultural resources, fish and wildlife habitat, and vegetation overlap with suitable habitat for these species. Requirements for surveys of BLM special status plant species reduces disturbance to these species from construction of utility systems and other facilities. In addition, these surveys may identify new locations of BLM special status plant species, thereby increasing knowledge of these species. The BLM would also consult with stakeholders in the permitting process to design projects in a manner that would minimize or avoid potential adverse effects to BLM special status plant species.
Surface-disturbing activities such as energy and mineral development, road construction, and other mechanized disturbance could cause adverse impacts to known BLM special status species plant populations and potential habitats, and undocumented populations. These activities fragment habitats, potentially isolating populations of BLM special status plants. Reclamation mitigates short-term impacts of surface disturbance by minimizing soil erosion and the establishment of invasive species. However, even with reclamation, surface-disturbing activities can have long-term adverse impacts to BLM special status plants through changes in the plant community structure or encroachment of invasive species. Under Alternative A, BLM actions are projected to result in 136,415 acres of short-term surface disturbance on BLM-administered land and 15,710 acres in the long term over the life of the plan (Table 4-1). Maintenance of healthy soil conditions enhances the viability, vigor, and abundance of BLM special status plant species.
Assuming exploration and development of minerals will continue in the Planning Area and potentially increase for some minerals, the potential for adverse impacts to special status plants will increase proportionately. Alternative A has the second-most acreage open to oil and gas leasing subject to the terms and conditions of the standard lease form only and the most acreage open with major constraints. Required pre-disturbance surveys, mitigation, and reclamation will minimize impacts from mineral development.
The spread of invasive species may adversely affect special status plant species, which are limited in size and distribution. However, due to management of invasive species, the BLM anticipates that adverse impacts from invasive species would be minimal, with cheatgrass being the species with the most potential to adversely impact special status plant species. Management of invasive species could directly benefit special status plants by eliminating direct competition and maintaining habitat health and diversity. In particular, eradication of invasive species in riparian areas (e.g., Tamarisk, Russian olive) benefits Ute ladies’-tresses and persistent sepal yellowcress. Under Alternative A, aerial application of pesticides is allowed on a case-by-case basis and livestock flushing is required on a case-by-case basis. Livestock flushing minimizes the transport of invasive species in fecal material onto or within BLM-administered lands.
The development of ROWs may result in habitat fragmentation and degradation resulting in adverse impacts to special status plants. The development and use of linear ROWs can also lead to an increase in the spread of invasive species resulting in adverse impacts to special status plants. ROWs concentrated in a corridor tend to localize or confine disturbance to a smaller area and reduce disturbance in areas identified as sensitive. Under Alternative A the BLM manages 61,416 acres as ROW exclusion areas, limiting adverse impacts.
Motorized vehicle use may adversely affect habitat for special status plants. Alternative A has the greatest acreage limited to existing roads and trails and the second least acreage closed to motorized vehicle use in the Planning Area. Invasive species are more likely to spread to areas with roads and trails used by motorized vehicles. Permitting off-road motorized vehicle use for big game retrieval and dispersed campsite access in areas with limited travel designations would result in soil disturbance, vegetation removal, and transport of invasive species. Motorized vehicle use is a threat to Rocky Mountain twinpod, Hyattville milkvetch, and Dubois milkvetch (Mills and Fertig 2000b; Fertig 200;, and Fertig 2000a), and is anticipated to indirectly and adversely impact known and unknown populations of special status plant species under Alternative A.
Under Alternative A, the Planning Area is open to livestock grazing, except in areas specifically closed including Bighorn River tracts, campgrounds, and exclosures. While trampling and herbivory from livestock grazing may result in direct adverse impacts to special status plant species, Alternative A manages livestock grazing to protect or enhance other resource values, minimizing adverse impacts. In addition, by instituting a ¼-mile buffer around riparian/wetland areas for placement of salt, mineral, or forage supplements, Alternative A minimizes adverse impacts to Ute ladies’-tresses and persistent sepal yellowcress.
Two existing ACECs that include special status species as their value of concern are Five Springs Falls and Upper Owl Creek, although other ACECs may also include BLM special status plant species. Protecting special status plants in these areas directly benefits the species known to occur there. Management of the Five Springs Falls ACEC and Upper Owl Creek ACEC includes NSO restrictions for leasable minerals, resulting in beneficial impacts to special status plants. While Upper Owl Creek ACEC is open to ROW authorizations, a detailed activity plan must be developed and approved before any surface-disturbing activity in the ACEC, which may minimize adverse impacts to special status plant species.
No WSRs are currently designated in the Planning Area; however, twenty waterways meet the WSR eligibility criteria. Management of these waterways to protect their ORVs and their free-flowing characteristics, results in beneficial impacts to Ute ladies’-tresses and persistent sepal yellowcress by minimizing disturbances to riparian/wetland habitat.
Soil compaction and erosion may result in indirect adverse and long-term impacts to special status plant species. Several special status plant species occur in areas with sparse vegetative cover, on steep slopes, and in rocky areas; therefore, management actions that limit activities in these areas and protect the integrity of the soils in the area, are anticipated to have beneficial impacts to these species. Alternative A does not require reclamation plans, although it reestablishes vegetation cover on disturbed soils within 5 years of initial seeding.
Changes in water management that reduce the periodicity of flooding may impact Ute ladies’-tresses and persistent sepal yellowcress (Heidel 2007 and Handley and Heidel 2008). Alternative A encourages the maintenance of natural flow regimes for streams supporting fisheries, but does not require it, which could adversely impact Ute ladies’-tresses and persistent sepal yellowcress.
Wildland fires may affect special status plant species by temporarily removing vegetation, changing plant community composition, and inhibiting plant succession. If special status plants depend on a specific seral stage or associative plants, a wildland fire could upset the ecological balance that supports a sensitive plant’s habitat or plant community. Wildland fire also may enhance habitat for special status plants and be a catalyst for their reestablishment and proliferation. Habitat degradation from invasion of Utah juniper due to fire suppression has been identified as a threat to Hyattville milkvetch (Fertig and Welp 2001). Alternative A utilizes wildland fires to restore fire-adapted ecosystems, which could benefit Hyattville milkvetch.
Alternative A manages all riparian/wetland areas to meet or make progress toward meeting PFC, but does not prioritize those not meeting PFC. Under Alternative A, the 500-foot buffer for surface-disturbing activities around riparian/wetland areas would reduce adverse impacts to special status plants in these areas. The buffer reduces the potential for direct removal of special status plants, sedimentation, and the potential for invasive species establishment, which have indirect adverse impacts to special status plant species.
Where restrictions of surface-disturbing activities are implemented for fish and wildlife habitats, special status plant habitats could be improved and adverse impacts to these species minimized. Alternative A institutes a TLS in big game crucial winter range and a CSU stipulation for big game migration corridors and parturition areas, and narrow ridges. Alternative A manages habitat, on a case-by-case basis, for the appropriate DPC based on the presence of special status species, potentially benefitting BLM special status plants in the long term.
Under Alternative A, proactive management actions implemented include reviewing actions, use authorizations, rangeland improvement projects, invasive species treatments, and fire suppression effects for potential impacts to BLM special status plant species before performing these tasks. For all these tasks, avoidance and mitigation measures are implemented on a case-by-case basis. These reviews are anticipated to benefit BLM special status plant species. Alternative A does not identify any buffer around BLM special status plant species for placement of forage supplements; however, mitigations to avoid BLM special status plant species are routinely applied at the site-specific activity level when appropriate.
Under Alternative B, BLM actions are projected to result in 73,919 acres of short-term surface disturbance to BLM-administered land and 10,882 acres of long-term surface disturbance over the life of the plan, the least acreage of all alternatives (Table 4-1). In addition to causing less surface disturbance, Alternative B reduces the potential for habitat fragmentation by maintaining large, contiguous blocks of native plant communities. The restrictions on habitat fragmentation and fewer disturbed acres relative to Alternative A are anticipated to indirectly benefit BLM special status plant species by protecting potential habitats, minimizing the spread of invasive species, and minimizing soil erosion.
Under Alternative B, approximately 2,296,279 acres are administratively unavailable to oil and gas leasing, approximately 14 times more acreage than under Alternative A, 15 times more acreage than under Alternative C, and eight times more acreage than under Alternative D. While required mitigation and reclamation under all alternatives minimizes adverse impacts from mineral development, Alternative B results in fewer adverse impacts to BLM special status plant species due to the greater acreage unavailable for oil and gas leasing. Alternative B has the least acreage open for oil and gas leasing subject to standard constraints, the least acreage available subject to moderate constraints, and the second greatest acreage subject to major constraints.
Invasive species spread would result in similar potential adverse impacts to those under Alternative A, but to a lesser extent. The BLM treats less acreage to eradicate or control the spread of invasive species under Alternative B; however, this alternative would cause less surface disturbance and the BLM employs greater measures to return disturbed areas to native vegetation communities, leaving less area vulnerable to invasive species establishment. Allowing the aerial application of pesticides within ½ mile of riparian/wetland areas to manage riparian weed species would beneficially impact the Ute ladies’-tresses and persistent sepal yellowcress. Overall, management of invasive species would have the least adverse impact to BLM special status plant species under Alternative B, compared to the other alternatives.
Alternative B designates the greatest acreage (225,750 acres) as exclusion areas for ROWs and corridors resulting in the greatest beneficial impacts to BLM special status plants by minimizing habitat fragmentation and degradation.
Under Alternative B, adverse impacts to BLM special status plant species from motorized vehicle use are anticipated to be the least of all the alternatives because Alternative B has the greatest acreage closed to motorized vehicle use, the least acreage limited to existing roads and trails, and the greatest acreage limited to designated roads and trails. Prohibiting off-road motorized vehicle use for big game retrieval and dispersed campsite access in areas with limited travel designations would also reduce the impacts from this action described under Alternative B. The anticipated soil disturbance, vegetation removal, and transport of invasive species under Alternative B are expected to produce the least indirect and adverse impacts to unknown populations of BLM special status plant species compared to other alternatives.
Livestock grazing is more limited under Alternative B than under alternatives A, C, and D as approximately 253,626 acres of crucial winter range for elk and bighorn sheep and 1,231,242 acres of greater sage-grouse Key Habitat Areas are closed to livestock grazing. Closing more acres to livestock grazing would result in less potential adverse impact to BLM special status plant species from trampling and herbivory. Additionally, Alternative B prohibits forage supplements within ½ mile of BLM special status plant species populations to minimize adverse impacts from livestock grazing. Expanding the McCullough Peaks HMA boundary may increase the extent of adverse impacts from wild horse grazing, but maintaining the initial appropriate management level for wild horses would not change the intensity of impacts. Alternative B would result in greater beneficial impacts to Ute ladies’-tresses and persistent sepal yellowcress than alternatives A, C, and D because of the larger buffer around riparian/wetland areas with respect to placement of forage supplements. In addition, Alternative B places more emphasis on meeting the rangeland health standards and maximizing multiple use benefits. More effective monitoring, management, and implementation of some grazing systems may benefit BLM special status plant species under Alternative B.
In addition to carrying forward the Five Springs Falls and Upper Owl Creek ACECs that emphasize protection of BLM special status plant species, Alternative B expands the existing Upper Owl Creek, Carter Mountain, and Little Mountain ACECs, and proposes designating Clarks Fork Canyon, Rattlesnake Mountain, and Sheep Mountain ACECs, all of which support BLM special status plant populations. Other ACECs under Alternative B may include BLM special status plant species as well. Designating these additional ACECs minimizes adverse impacts to the BLM special status plant populations within the boundaries of the ACECs because managing these areas helps protect these populations. This alternative provides the greatest opportunity to maintain BLM special status plant habitats in special designations.
Alternative B manages 20 waterways as suitable for inclusion in the NWSRS, which includes approximately 26,761 acres in the Planning Area. This alternative prohibits surface-disturbing activities on BLM-administered lands in the WSR suitable waterways, withdraws the segments from appropriation under the mining laws, closes the areas to geophysical exploration, and manages the segments as ROW exclusion areas. This type of management protects the values of the segments more than under Alternative A. Alternatives C and D do not recommend any segments as suitable for inclusion in the NWSRS; therefore, the anticipated beneficial impacts to BLM special status plant species under Alternative B are more than under alternatives A, C, and D.
Alternative B includes additional protective measures for soils compared to Alternative A. Reclamation plans are developed and approved before starting any surface-disturbing activities, areas are reclaimed based on pre-existing plant communities, and inventories and mapping of soils to determine erosion and degree of soil stability are completed. By understanding the soils better, the BLM can institute required BMPs that will be most effective in each area, thereby potentially reducing erosion, and minimizing adverse impacts to BLM special status plant species. The anticipated level of soil erosion and compaction are expected to be less under Alternative B than under alternatives A, C, and D.
While Alternative A may fence springs and reservoirs to meet resource objectives, Alternative B may also fence riparian/wetland areas as necessary, potentially increasing the beneficial impacts to BLM special status plant species in these habitats. In addition, Alternative B maintains natural flow regimes for streams supporting fisheries. This is important to Ute ladies’-tresses and persistent sepal yellowcress, which depend on periodic flooding events during their life-cycles. Alternative B (and alternatives A and D) has additional beneficial impacts to BLM special status plant species compared to Alternative C because it reduces sediment loading in streams by developing and implementing watershed improvement practices.
Under Alternative B, the BLM utilizes wildland fire and other vegetation treatments to restore fire-adapted ecosystems, which could result in the same or fewer beneficial impacts to Hyattville milkvetch than Alternative A because Alternative B relies mostly on natural processes, and less on active restoration. Wildland fire and other vegetation treatments could be used to reduce the invasion of Utah juniper into Hyattville milkvetch habitat.
Alternative B is anticipated to result in greater beneficial impacts to BLM special status plants in riparian/wetland habitats than Alternative A because Alternative B manages these habitats to achieve DPC, prioritizes those areas not meeting PFC, and increases the buffer prohibiting surface-disturbing activities around riparian/wetland habitats to ¼ mile. Through these management actions, the potential for direct removal of BLM special status plants, sedimentation, and spread of invasive plants is less than under Alternative A. In addition, Alternative B applies an NSO restriction to wetlands larger than 40 acres.
Alternative B provides more protections to big game crucial winter range and parturition areas by establishing the Absaroka Front Management Area and applying an NSO restriction to these ranges and areas elsewhere, and prohibiting surface disturbance within ½ mile of migration corridors. These restrictions result in beneficial impacts to BLM special status plants in these areas, by reducing removal and trampling of these species. Because the restrictions are NSO, the beneficial impacts are anticipated to be greater than under Alternative A.
Alternative B includes the greatest amount of restrictions for the protection of special status plant species habitat and provides the greatest amount of protection to known populations of BLM special status plants compared to the other alternatives. Range improvement projects are not allowed within ½ mile of known BLM special status plant species, forage supplements are prohibited within ½ mile of BLM special status plants, aerial applications of pesticides are prohibited with 1 mile of BLM special status plants, and surveys are required in potential BLM special status plant habitats before approving any project. The increased buffers and required surveys compared to Alternative A aid in habitat protection and potential expansion of BLM special status plant populations.
Under Alternative C, BLM actions are projected to result in 245,783 acres of short-term surface disturbance on BLM-administered land and 41,545 acres of surface disturbance in the long term over the life of the plan, the greatest acreage of all alternatives (and more than double the acreage of Alternative A) (Table 4-1). Similar to Alternative A, Alternative C increases the potential for habitat fragmentation by not maintaining large, contiguous blocks of native plant communities. By having fewer restrictions on habitat fragmentation and disturbing more acres than alternatives A, B, and D, Alternative C is anticipated to indirectly benefit BLM special status plant species less than the other alternatives. The spread of invasive species and extent of soil erosion would be greatest under Alternative C.
Alternative C has the greatest acreage open to oil and gas development subject to standard constraints, the second greatest acreage subject to moderate constraints, the second least acreage subject to major constraints, and the least acreage administratively unavailable to oil and gas development. While required mitigation and reclamation under all alternatives minimizes adverse impacts from mineral development, Alternative C could result in the greatest adverse impacts to BLM special status plant species due to implementing the least restrictions to these activities.
Under Alternative C, implementing a ½-mile buffer around BLM special status plant species prohibiting aerial herbicide application may result in less adverse impacts from invasive species management to Ute ladies’-tresses and persistent sepal yellowcress than under alternatives A and D (under which aerial application is permitted), but more than Alternative B (under which the BLM implements a 1-mile buffer). Alternative C allows exceptions to this buffer to manage riparian weed species, which could benefit Ute ladies’-tresses and persistent sepal yellowcress in the long term. Under Alternative C, impacts from transport of invasive species by livestock are anticipated to be greater than any other alternative, as flushing of livestock is not required.
Under Alternative C, adverse impacts to BLM special status plant species from OHV use are anticipated to be the greatest of all the alternatives because Alternative C has the least acreage closed to motorized vehicle use, the second greatest acreage limited to existing roads and trails, the second least acreage limited to designated roads and trails, and the greatest acreage open. Permitting off-road motorized vehicle use for big game retrieval and dispersed campsite access in areas with limited travel designations would result in impacts similar to those described for Alternative A, but to a greater extent by allowing the creation of new travel routes. The anticipated soil disturbance, vegetation removal, and transport of invasive species under Alternative C are expected to produce the most indirect and adverse impacts to unknown populations of BLM special status plant species compared to other alternatives.
Similar to alternatives A and D, livestock grazing is closed on Bighorn River tracts, campgrounds, and exclosures. Alternative C may result in greater adverse impacts to Ute ladies’-tresses and persistent sepal yellowcress than alternatives A, B, and D by allowing placement of forage supplements in riparian/wetland areas. Alternative C (and Alternative D) allows the placement of forage supplements after considering the location of BLM special status plant species, which may increase the risk of herbivory and trampling. In addition, Alternative C places more emphasis on livestock forage availability while meeting multiple use objectives. Overall, adverse impacts to BLM special status plants from livestock grazing management under Alternative C are anticipated to be similar to alternatives A and D and greater than Alternative B.
Under Alternative C, only the existing Brown/Howe Dinosaur Area and Spanish Point Karst ACECs are carried forward and no new ACECs are designated. No BLM special status plant species are known to occur in either ACEC. Therefore, beneficial impacts to special status plants from designation and management of ACECs would be the least under Alternative C.
Under Alternative C, does not recommend any WSR eligible waterway segments as suitable for inclusion in the NWSRS. By releasing these areas for other uses to be managed in accordance with adjacent BLM-administered lands, the potential for adverse impacts to Ute ladies’-tresses and persistent sepal yellowcress is greater than alternatives A and B.
Alternative C includes additional protective measures for soils compared to Alternative A, so that reclamation plans are developed on a case-by-case basis and 30 percent desired vegetative cover is required within three growing seasons. The anticipated level of soil erosion and compaction are expected to be similar to Alternative A.
While Alternative A may fence springs and reservoirs, Alternative C may fence springs and their associated wetland areas, potentially increasing the beneficial impacts to BLM special status plant species in these habitats. Alternative C manages for adequate in-stream flow to support riparian and fisheries values, which may provide fewer beneficial impacts than maintaining natural flow regimes as under alternatives A, B, and D. Because Alternative C only implements BMPs on permitted activity plans to reduce sediment loading in streams and river segments, it would have fewer beneficial impacts to BLM special status plant species than alternatives A, B, and D.
Under Alternative C, the BLM utilizes wildland fire and other vegetation treatments to restore fire-adapted ecosystems, similar to Alternative B, except that under Alternative C active restoration is used, which may create a greater beneficial impact than natural processes alone. This may result in more beneficial impacts to Hyattville milkvetch than Alternative A. Wildland fire and other vegetation treatments could be used to reduce the invasion of Utah juniper into Hyattville milkvetch habitat.
Alternative C may result in similar beneficial impacts to BLM special status plants in riparian/wetland habitats as Alternative A because both alternatives manage these habitats to meet PFC. In addition, Alternative C prioritizes areas functioning at-risk with a downward trend and areas in a nonfunctioning condition. However, Alternative C allows surface-disturbing activities in riparian/wetland areas on a case-by-case basis, potentially increasing adverse impacts to BLM special status plants in these areas. Through these management actions, the potential for direct removal of BLM special status plants, sedimentation, and spread of invasive plants is greater than under alternatives A, B, and D. Similar to Alternative A, Alternative C does not apply an NSO restriction to wetland areas greater than 40 acres.
Alternative C provides fewer protections to big game crucial winter range, parturition areas, and migration corridors than alternatives A, B, and D. By allowing activities in these areas, Alternative C results in the fewest beneficial impacts to BLM special status plants in these areas because these species may be removed or trampled.
Alternative C sets aside the least amount of land of any alternative for areas that have management actions to benefit BLM special status plant species. Similar to Alternative B, buffers and restrictions for other resources and surface-disturbing activities around BLM special status plant species will likely provide indirect beneficial impacts to habitats for special status plants. Range improvement projects are not allowed within ½ mile of known BLM special status plant species, forage supplements are prohibited within 300 feet of BLM special status plants, and aerial applications of pesticides are prohibited with ½ mile of BLM special status plants, but surveys are only required in potential habitats for federally listed, proposed, or candidate species before approving any project. The increased buffers and requirement of some surveys compared to Alternative A aid in habitat protection and the potential expansion of the special status plant populations.
Under Alternative D, BLM actions are projected to result in 140,507 acres of short-term surface disturbance on BLM-administered land and 18,443 acres of surface disturbance over the life of the plan, the second most acreage compared to the other alternatives. However, similar to Alternative B, Alternative D reduces the potential for habitat fragmentation by maintaining large, contiguous blocks of native plant communities. Although the BLM allows the use of nonnative seeds that may slow the reestablishment of native plant communities, reclamation practices under Alternative D, would mitigate short-term impacts of surface disturbance more than under Alternative A. Overall, surface disturbance under Alternative D would result in impacts similar to those under Alternative A.
Alternative D has approximately 257,512 acres open to oil and gas leasing subject to the terms and conditions of the standard lease form, approximately one-fifth of the acreage under Alternative A, and has almost two times more acreage administratively unavailable to oil and gas leasing than under Alternative A. Minerals development under Alternative D would result in fewer adverse impacts to BLM special status plant species than under alternatives A and C, but more than under Alternative B.
Adverse impacts from management of invasive species under Alternative D would be similar to those under Alternative A. Alternative D results in more surface disturbance than Alternative A, leaving more areas vulnerable to invasive species spread, but employs more measures to restore vegetation in disturbed areas and places more restrictions on motorized travel that can spread invasive species.
Alternative D manages 22,413 fewer acres as ROW exclusion areas than Alternative A but approximately 2½ times more acreage as ROW avoidance/mitigation areas, which would result in more beneficial impacts to special status plant species than under alternatives A and C, but less than under Alternative B.
Under Alternative D, adverse impacts to BLM special status plant species from motorized vehicle use would be more than under Alternative B, but less than under alternatives A and C because Alternative D closes a similar amount of acreage to motorized vehicle use as Alternative A but designates the second-most acreage—a 34 percent increase compared to Alternative A—as limited to designated roads and trails. Restricting off-road motorized vehicle use for big game retrieval and dispersed campsite access in areas with limited travel designations to within 300 feet of established roads would limit the adverse impacts described under Alternative A.
Impacts from livestock grazing management under Alternative D would be similar to those under Alternative A. Allowing the use of livestock grazing, even in closed areas, as a tool to improve resource conditions may beneficially affect BLM special status plant species if grazing is used to enhance native plant communities.
Special designations under Alternative D would result in similar beneficial impacts as those under Alternative B, but to a lesser extent. Alternative D carries forward the Five Springs Falls, Upper Owl Creek, Carter Mountain, and Little Mountain ACECs, and proposes designating the Clarks Fork Canyon and Sheep Mountain ACECs. Alternative D would designate more acreage in ACECs than alternatives A and C, but less than Alternative B. Not recommending WSR eligible waterway segments as suitable for inclusion in the NWSRS would result in similar potential adverse impacts as those under Alternative C.
Alternative D includes additional protective measures for soils compared to alternatives A and C, but less than Alternative B. Alternative D requires reclamation plans, stipulations, or measures before authorized surface-disturbing activities and develops reclamation plans in coordination with stakeholders. The anticipated level of soil erosion and compaction are expected to be less under Alternative D than under alternatives A and C, but more than under Alternative B.
Similar to Alternative A, Alternative D does not require the maintenance of natural flow regimes for streams supporting fisheries, which would result in similar adverse impacts. Developing watershed improvement projects and fencing springs, wetlands, reservoirs, and riparian areas to meet resource objectives would result in similar beneficial impacts to those under Alternative B.
Fire and fuels management under Alternative D would result in impacts to BLM special status plant species similar to those under Alternative A.
Alternative D would result in beneficial impacts to BLM special status plant species in riparian/wetland habitats similar to Alternative A, but to a greater extent because the BLM manages areas with unique fisheries or recreational value toward achieving DFC. Management toward DFC is assumed to exceed the requirements of managing toward PFC and would therefore result in improved functioning and healthier riparian/wetland areas. Avoiding surface-disturbing activities within 500 feet of riparian/wetland areas and ¼ mile of sensitive riparian/wetland areas would reduce adverse impacts to BLM special status plant species in these areas similarly to Alternative A. Alternative D also applies an NSO on wetlands greater than 20 acres, resulting in similar beneficial impacts as those under Alternative B, but to a greater extent.
Alternative D provides similar beneficial impacts as those under Alternative B by establishing the Absaroka Front Management Area, but to a lesser extent. Alternative D restricts mineral development in this area less than Alternative B—by using a mix of CSU, TLS, NSO, and unavailable for leasing restrictions—but more than Alternative C and Alternative A (under which this management area is not recognized). Potential adverse impacts to special status plant species from wild horse grazing under Alternative D would be similar to those described under Alternative B.
Alternative D avoids range improvement projects that may concentrate herbivory within ¼ mile of BLM special status plant species, unless the project is determined not to adversely impact that population; allows the placement of forage supplements after considering their proximity to BLM special status plant species; implements avoidance and mitigation measures for projects and activities in coordination with surface owners on split-estate; avoids aerial applications of herbicides within ½ mile of BLM special status plant species; and allows the application of fire suppression chemicals within ¼ mile of known/documented populations of BLM special status plant species with consent of the authorized officer. Overall, these measures would result in more beneficial impacts to BLM special status plant species than alternatives A and C, but less than Alternative B.