In the Bighorn Basin, the BLM determines the presence of special status plant species through inventory within likely habitats on a case-by-case basis. Restrictions in areas with known populations of special status plants are also determined on a case-by-case basis. The Wyoming Natural Diversity Database maintains a list of Wyoming plant species of special concern and provides information on global and state abundance, legal status, and state distribution. Species in Wyoming are considered to be of special concern if (1) the species is vulnerable to extinction at the global or state level due to inherent rarity, (2) the species has experienced a substantial loss of habitat, or (3) the species is sensitive to human-caused mortality or habitat disturbances.
The BLM is responsible for managing habitat for special status plant species. Special status species considered in this analysis are those listed as threatened or endangered under the ESA, those proposed for listing or that are candidates for listing under the provisions of the ESA, and those the BLM State Director or the state of Wyoming have designated as sensitive.
One threatened species, Ute ladies’-tresses, could occur in the Planning Area; 11 BLM sensitive species are known to occur. Of the 11 BLM sensitive species, eight are also Wyoming plant species of concern and one is a Wyoming plant species of potential concern. In addition, the following plants are Wyoming species of concern that are not threatened or endangered and do not appear on the BLM Sensitive Species List: Big Horn fleabane, Cary’s beardtongue, hairy prince’s plume, and Hapemans’ coolwart. These species are listed in the Natural Diversity Database, which the University of Wyoming maintains, and are not further discussed in this section.
Special status plant species are found in a variety of habitats in the Planning Area. The landscape in the area exhibits diverse climates, topography, and soils. Table 3–30 lists habitat associations for special status plants that are known to occur or may be found on BLM-administered land in the Planning Area.
Table 3.30. Special Status Plant Species Habitat in the Planning Area
| Common Name | Habitat | Status |
|---|---|---|
| Ute ladies’-tresses | Mesic to wet riparian meadows, marshes, stream banks between 4,300 and 5,900 feet amsl. | Threatened |
| Absaroka beardtongue | Sparsely vegetated openings on steep slopes of loose volcanic rubble or outcrops of dry and esitic volcanic rock at 5,920 to 10,000 feet amsl. | Wyoming Plant Species of Concern BLM Sensitive Plant Species |
| Dubois milkvetch | Barren shale, badlands, limestone, and redbed slopes and ridges at 6,900 to 8,800 feet amsl. | Wyoming Plant Species of Concern BLM Sensitive Plant Species |
| Evert’s wafer-parsnip | Coarse volcanic soils or sandstone outcrops dominated by cushion plants or sparse shrublands in openings within Rocky Mountain juniper or limber pine woodlands at 5,900 to 10,900 feet amsl. | Wyoming Plant Species of Concern BLM Sensitive Plant Species |
| Hyattville milkvetch | Sparsely vegetated stony ridges and barren red clay slopes 4,900 to 5,900 feet amsl. | Wyoming Plant Species of Concern BLM Sensitive Plant Species |
| Limber pine | Timberline and at lower elevation with sagebrush. | BLM Sensitive Plant Species |
| Persistent sepal yellowcress | Riverbanks and shorelines, usually on sandy soils near high water line. | Wyoming Plant Species of Potential Concern BLM Sensitive Plant Species |
| Rocky Mountain twinpod | Sparsely vegetated rocky slopes of limestone, sandstone or clay 5,600 to 8,300 feet amsl. | Wyoming Plant Species of Concern BLM Sensitive Plant Species |
| Shoshonea | Shallow, stony calcareous soils of exposed limestone outcrops, ridgetops, and talus slopes 5,900 to 9,200 feet amsl. | Wyoming Plant Species of Concern BLM Sensitive Plant Species |
| Whitebark pine | Montane forests and on thin, rocky, cold soils at or near timberline at 4,265 to 12,139 feet amsl. | BLM Sensitive Plant Species |
| William’s wafer-parsnip | Open ridgetops and upper slopes with exposed limestone outcrops or rockslides 6,000 to 8,300 feet amsl. | Wyoming Plant Species of Concern BLM Sensitive Plant Species |
| Wyoming tansymustard | Sparsely vegetated sandy slopes at base of cliffs of volcanic breccias or sandstone 8,300 to 10,000 feet amsl. | Wyoming Plant Species of Concern BLM Sensitive Plant Species |
| Source: BLM 2010a amsl above mean sea level BLM Bureau of Land Management | ||
Most of the trends that affect other plant species in the Planning Area also affect special status species. These include habitat degradation and fragmentation, grazing practices and management, invasive species, motor vehicles, and climate. Under current management, special status plant species are not expected to decline (BLM 2009b). These plants are on the BLM Sensitive Species List to ensure actions on BLM-administered lands consider the welfare of these species and do not contribute to the need to list any other special status species under the provisions of the ESA. The following paragraphs briefly describe each of the nine special status plant species. Unless otherwise noted, specific information on trends and occurrences for each of the species is not available.
Ute ladies’-tresses is a federally threatened plant species. This species occurs in mesic to wet riparian meadows, marshes, and stream banks between 4,300 and 5,900 feet amsl. Typical settings for Ute ladies’-tresses can include gravel bars, wet meadow terraces, oxbows, seeps, springs, fens, lakes, and potentially ditches and quarries (Heidel 2007).
The Absaroka beardtongue is a BLM sensitive plant species and a Wyoming plant species of concern. This species occurs in sparsely vegetated openings on steep slopes of loose volcanic rubble or outcrops of dry and esitic volcanic rock at 5,920 to 10,000 feet amsl. Typical settings for Absaroka beardtongue include very barren, steep slopes with little competition from other vegetation (Mills and Fertig 2000a). Absaroka beardtongue is known to occur in the Absaroka Range of northwest Wyoming (Mills and Fertig 2000a).
Dubois milkvetch is a BLM sensitive plant species and a Wyoming plant species of concern. This species occurs in barren shale, badlands, limestone, and redbed slopes and ridges at 6,900 to 8,800 feet amsl. Typical settings for Dubois milkvetch include mid to upper slopes near the crest of badland ridges or low knolls (Fertig 2000a).
Evert’s wafer-parsnip is a BLM sensitive plant species and a Wyoming plant species of concern. This species occurs in coarse volcanic soils or sandstone outcrops dominated by cushion plants or shaded rock outcrops and ridges adjacent to Rocky Mountain juniper or limber pine woodlands at 5,900 to 10,900 feet amsl (Fertig 2000b).
Hyattville milkvetch is a BLM sensitive plant species and a Wyoming plant species of concern. This species occurs in sparsely vegetated stony ridges and barren red clay slopes at 4,900 to 5,900 feet amsl. Hyattville milkvetch is mostly found on outcrops of the Goose Egg and Chugwater formations with some beds of Ten Sleep Sandstone; plants are usually absent from gypsum-rich deposits (Fertig 2001). Hyattville milkvetch is found on the eastern rim of the Bighorn Basin and western foothills of the Big Horn Range near Hyattville, Wyoming (Fertig 2001).
Limber pine is a BLM sensitive plant species. This species occurs in high montane forests, often at timberline (Flora of North America 1993a). It occurs at elevations of 4,900 to 11,000 feet amsl (Flora of North America 1993a). Species associated with limber pine include Rocky Mountain lodgepole pine, Engelmann spruce, whitebark pine, Rocky Mountain Douglas-fir, subalpine fir, Rocky Mountain juniper, mountain mahogany, and common juniper.
Persistent sepal yellowcress is a BLM sensitive plant species and a Wyoming plant species of potential concern. This species occurs on moist, sandy to muddy riverbanks and shorelines, usually near the high water line (Handley and Heidel 2008).
Rocky Mountain twinpod is a BLM sensitive plant species and a Wyoming plant species of concern. This species occurs on sparsely vegetated rocky slopes of limestone, sandstone or clay at 5,600 to 8,300 feet amsl. Rocky Mountain twinpod is endemic to the Bighorn Basin and Absaroka Range (Mills and Fertig 2000b).
Shoshonea is a BLM sensitive plant species and a Wyoming plant species of concern. This species occurs in shallow, stony calcareous soils of exposed limestone outcrops, ridgetops, and talus slopes at 5,900 to 9,200 feet amsl. Shoshonea is associated with other low-growing forbs and cushion plants on sites with sparse cover (Fertig and Mills 2000). Shoshonea is known to occur in the eastern Absaroka and Owl Creek Mountains (Fertig and Mills 2000).
Whitebark pine is a BLM sensitive plant species. This species occurs on thin, rocky, cold soils at or near timberline in montane forests (Flora of North America 1993b).
William’s wafer-parsnip is a BLM sensitive plant species and a Wyoming plant species of concern. This species occurs on open ridgetops and upper slopes with exposed limestone outcrops or rockslides at 6,000 to 8,300 feet amsl. Soils tend to be thin and sandy, and often restricted to small cracks in the limestone bedrock (Fertig 2000c). William’s wafer-parsnip is restricted to the Big Horn Mountains (Fertig 2000c).
Wyoming tansymustard is a BLM sensitive plant species and a Wyoming plant species of concern. This species occurs in sandy soil at the base of cliffs composed of volcanic breccias or sandstone (Fertig 2000d) at elevations of 8,300 to 10,000 feet amsl.
Management challenges for special status plant species in the Planning Area include preventing declining population trends for select species; occurrence of drought; spread; maintaining PFC for riparian/wetland habitats; vegetation treatment with prescribed fire or herbicides; lack of periodic disturbance events (e.g., fire, flood, and grazing); physical trampling (e.g., from OHV use); loss of habitat resulting from altered hydrology; and challenges presented by special status plant populations occurring over multiple land ownerships. While threats to some species might remain low due to remote habitat, threats to other species might increase despite distance or restricted access. For example, special status plant species that depend on groundwater levels could be affected by upstream depletions of groundwater far removed from affected plant populations. In addition, early successional special status plant species protected from habitat alteration could still be adversely affected by natural succession and the lack of fire, flooding, or other disturbance factors necessary to retain early successional habitat.