Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List Astragalus microcymbus and Astragalus schmolliae as Endangered or Threatened

DEPARTMENT OF THE INTERIOR Fish and Wildlife Service 50 CFR Part 17 [FWS-R6-ES-2010-0080; MO 92210-0-0008-B2] Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List Astragalus microcymbus and Astragalus schmolliae as Endangered or Threatened AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Notice of 12-month petition finding.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service/USFWS), announce a 12-month finding on a petition to list Astragalus microcymbus (skiff milkvetch) and Astragalus schmolliae (Schmoll's milkvetch) as endangered or threatened, and to designate critical habitat under the Endangered Species Act of 1973, as amended (Act). After a review of all the available scientific and commercial information, we find that listing A. microcymbus and A. schmolliae is warranted. However, currently listing of A. microcymbus and A. schmolliae is precluded by higher priority actions to amend the Lists of Endangered and Threatened Wildlife and Plants. Upon publication of this 12-month petition finding, we will add A. microcymbus and A. schmolliae to our list of candidate species. We will make any determinations on critical habitat during development of the proposed listing rule. In any interim period, the status of the candidate taxon will be addressed through our annual Candidate Notice of Review.

DATES:

The finding announced in this document was made on December 15, 2010.

ADDRESSES:

This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R6-ES-2010-0080. Supporting documentation we used in preparing this finding is available for public inspection, by appointment, during normal business hours at the Western Colorado Ecological Services Office, U.S. Fish and Wildlife Service, 764 Horizon Drive, Suite B, Grand Junction, CO 81506-3946. Please submit any new information, materials, comments, or questions concerning this finding to the above address

80. Supporting documentation we used in preparing this finding is available for public inspection, by appointment, during normal business hours at the Western Colorado Ecological Services Office, U.S. Fish and Wildlife Service, 764 Horizon Drive, Suite B, Grand Junction, CO 81506-3946. Please submit any new information, materials, comments, or questions concerning this finding to the above address.

FOR FURTHER INFORMATION CONTACT:

Al Pfister, Field Supervisor, Western Colorado Ecological Services Office ( see ADDRESSES ); by telephone, 970-243-2778; or by facsimile, 970-245-6933. Persons who use a telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Background

Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq. ), requires that, for any petition to revise the Federal Lists of Endangered and Threatened Wildlife and Plants that contains substantial scientific or commercial information that listing the species may be warranted, we make a finding within 12 months of the date of receipt of the petition. In this finding, we will determine that the petitioned action is: (a) Not warranted, (b) warranted, or (c) warranted, but immediate proposal of a regulation implementing the petitioned action is precluded by other pending proposals to determine whether species are threatened or endangered, and expeditious progress is being made to add or remove qualified species from the Federal Lists of Endangered and Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires that we treat a petition for which the requested action is found to be warranted but precluded as though resubmitted on the date of such finding, that is, requiring a subsequent finding to be made within 12 months. We must publish these 12-month findings in the Federal Register

species from the Federal Lists of Endangered and Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires that we treat a petition for which the requested action is found to be warranted but precluded as though resubmitted on the date of such finding, that is, requiring a subsequent finding to be made within 12 months. We must publish these 12-month findings in the Federal Register .

In accordance with the President's memorandum of April 29, 1994, Government-to-Government Relations with Native American Tribal Governments (59 FR 22951), Executive Order 13175, titled Consultation and Coordination with Indian Tribal Governments (65 FR 67249), and the Department of the Interior's manual on Departmental Responsibilities for Indian Trust Resources, at 512 DM 2, we acknowledge our responsibility to communicate meaningfully with recognized Federal Tribes on a government-to-government basis. In accordance with Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights, Federal-Tribal Trust Responsibilities, and the Endangered Species Act), we readily acknowledge our responsibilities to work directly with the Tribes in developing programs for healthy ecosystems, to acknowledge that Tribal lands are not subject to the same controls as Federal public lands, to remain sensitive to Indian culture, and to make information available to Tribes. In fulfilling our trust responsibilities for government-to-government consultation with Tribes, we met with the Ute Mountain Ute Tribe regarding the process we would take to conduct a 12-month status review of Astragalus schmolliae. As an outcome of our government-to-government consultation, we recognize the sovereign right of the Ute Mountain Ute Tribe to manage the habitat for A. schmolliae on its tribal lands, and acknowledge that right in this 12-month finding.

Previous Federal Actions

Federal action for Astragalus microcymbus and Astragalus schmolliae (then A. schmollae ) began as a result of section 12 of the Act of 1973, as amended (16 U.S.C

ment-to-government consultation, we recognize the sovereign right of the Ute Mountain Ute Tribe to manage the habitat for A. schmolliae on its tribal lands, and acknowledge that right in this 12-month finding.

Previous Federal Actions

Federal action for Astragalus microcymbus and Astragalus schmolliae (then A. schmollae ) began as a result of section 12 of the Act of 1973, as amended (16 U.S.C. 1531 et seq. ), which directed the Secretary of the Smithsonian Institution to prepare a report on plants considered to be endangered, threatened, or extinct in the United States. This report, designated as House Document No. 94-51, was presented to Congress on January 9, 1975. In that document, both species were designated as endangered (House Document 94-51, pp. 57-58). On July 1, 1975, the Service published a notice in the Federal Register (40 FR 27823, p. 27847) of its acceptance of the Smithsonian report as a petition within the context of section 4(c)(2) (now section 4(b)(3)) of the Act, and giving notice of its intention to review the status of the plant taxa therein.

As a result of that review, the Service published a proposed rule on June 16, 1976, in the Federal Register (41 FR 24523, pp. 24543-24544) to determine endangered status pursuant to section 4 of the Act for approximately 1,700 vascular plant taxa, including Astragalus microcymbus and Astragalus schmolliae. The list of 1,700 plant taxa was assembled on the basis of comments and data received by the Smithsonian Institution, and the Service in response to House Document No. 94- 51 and the July 1, 1975, Federal Register publication. General comments received in response to the 1976 proposal are summarized in an April 26, 1978, Federal Register publication (43 FR 17909). In 1978, amendments to the Act required that all proposals more than 2 years old be withdrawn. A 1-year grace period was given to proposals already more than 2 years old

response to House Document No. 94- 51 and the July 1, 1975, Federal Register publication. General comments received in response to the 1976 proposal are summarized in an April 26, 1978, Federal Register publication (43 FR 17909). In 1978, amendments to the Act required that all proposals more than 2 years old be withdrawn. A 1-year grace period was given to proposals already more than 2 years old. On December 10, 1979, the Service published a notice in the Federal Register (44 FR 70796) withdrawing the portion of the June 16, 1976, proposal that had not been made final which removed both A. microcymbus and A. schmolliae from proposed status but retained both species as candidate plant

On December 15, 1980, the Service published a current list of those plant taxa native to the United States being considered for listing under the Act where Astragalus microcymbus and Astragalus schmolliae were identified as a category 2 taxon “currently under review” (45 FR 82479, pp. 82490-82491). On November 28, 1983, A. schmolliae was moved to the “taxa no longer under review” list, and given a 3C rank indicating the species was proven to be more abundant or widespread than previously believed or not subjected to an identifiable threat (48 FR 53640, pp. 53641, 53662). The two species also were included as a category 2 species ( A. schmolliae was not included as a 3C species despite the conclusions of the 1983 review) on September 27, 1985 (50 FR 39525, p. 39533-39534), February 21, 1990 (55 FR 6184, p. 6190), and September 30, 1993 (58 FR 51144, pp. 51151-51152). The category 2 species designation was defined as having enough information to indicate that listing the species as an endangered or threatened species was possibly appropriate.

On October 22, 1993, we received a petition dated October 19, 1993, from the Biodiversity Legal Foundation and Lee Dyer requesting that Astragalus microcymbus be listed as endangered under the Act, and that critical habitat be designated (Carlton et al. 1993, pp. 1-11)

having enough information to indicate that listing the species as an endangered or threatened species was possibly appropriate.

On October 22, 1993, we received a petition dated October 19, 1993, from the Biodiversity Legal Foundation and Lee Dyer requesting that Astragalus microcymbus be listed as endangered under the Act, and that critical habitat be designated (Carlton et al. 1993, pp. 1-11). The petition included biological information regarding the species and several scientific articles in support of the petition. After careful consideration, we did not issue a 90-day finding on the petition because the species was already included as a category 2 species (Spinks 1994, pp. 1-8).

On February 28, 1996, we proposed removing all category 2 species, including Astragalus microcymbus and Astragalus schmolliae, from our candidate species notice of review (61 FR 7596). This policy change was finalized on December 5, 1996, stating that the list was not needed because of other lists already maintained by other entities such as Federal and State agencies (61 FR 64481).

On July 30, 2007, we received a petition dated July 24, 2007, from Forest Guardians (now WildEarth Guardians) requesting that the Service: (1) Consider all full species in our Mountain Prairie Region ranked as G1 or G1G2 by the organization NatureServe, except those that are currently listed, proposed for listing, or candidates for listing; and (2) list each species as either endangered or threatened (Forest Guardians 2007, pp. 1-37). The petition incorporated all analyses, references, and documentation provided by NatureServe in its online database at http://www.natureserve.org/ into the petition. We acknowledged the receipt of the petition in a letter to the Forest Guardians, dated August 24, 2007 (Slack 2007, p. 1). In that letter we stated that, based on preliminary review, we found no evidence to support an emergency listing for any of the species covered by the petition, and that we planned work on the petition in Fiscal Year (FY) 2008

at http://www.natureserve.org/ into the petition. We acknowledged the receipt of the petition in a letter to the Forest Guardians, dated August 24, 2007 (Slack 2007, p. 1). In that letter we stated that, based on preliminary review, we found no evidence to support an emergency listing for any of the species covered by the petition, and that we planned work on the petition in Fiscal Year (FY) 2008.

On March 19, 2008, WildEarth Guardians filed a complaint (1:08-CV-472-CKK) indicating that the Service failed to comply with its mandatory duty to make a preliminary 90-day finding on their two multiple species petitions—one for the Mountain-Prairie Region, and one for the Southwest Region ( WildEarth Guardians v. Kempthorne 2008, case 1:08-CV-472-CKK). We subsequently published two 90-day findings on January 6, 2009 (74 FR 419), and February 5, 2009 (74 FR 6122), identifying species for which we were then making negative 90-day findings, and species for which we were still working on a determination. On March 13, 2009, the Service and WildEarth Guardians filed a stipulated settlement in the District of Columbia Court, agreeing that the Service would submit to the Federal Register a finding as to whether WildEarth Guardians' petition presents substantial information indicating that the petitioned action may be warranted for 38 Mountain-Prairie Region species by August 9, 2009 ( WildEarth Guardians v. Salazar 2009, case 1:08-CV-472-CKK).

On August 18, 2009, we published a partial 90-day finding for the 38 Mountain-Prairie Region species, and found that the petition presented substantial information to indicate that listing of Astragalus microcymbus may be warranted based on threats from off-road vehicle use and drought; and that listing Astragalus schmolliae may be warranted based on threats from fire, nonnative species invasions, road construction, grazing, and drought; and went on to request further information from the public pertaining to both species (74 FR 41649, pp. 41655-41656)

ation to indicate that listing of Astragalus microcymbus may be warranted based on threats from off-road vehicle use and drought; and that listing Astragalus schmolliae may be warranted based on threats from fire, nonnative species invasions, road construction, grazing, and drought; and went on to request further information from the public pertaining to both species (74 FR 41649, pp. 41655-41656).

This notice constitutes the 12-month finding on the July 24, 2007, petition to list Astragalus microcymbus and Astragalus schmolliae as threatened or endangered. Given that we are doing 12-month findings for 38 species from this petition, and 67 species from the Southwest Region multiple species petition (74 FR 419, January 6, 2009; 74 FR 66866, December 16, 2009), and given the amount of resources that it takes to complete a 12-month finding, we are unable to complete 12-month findings for all these species at this time.

Species Information—Astragalus Microcymbus

Species Description and Taxonomy

Astragalus microcymbus is a perennial forb (a plant that can live to more than 3 years of age and without grass-like, shrub-like, or tree-like vegetation) that dies back to the ground every year. The plant has slender stems that are sparsely branched with dark green pinnate leaves, with 9-15 leaflets arranged in an evenly spaced fashion along either side of a central axis. It is in the pea (Fabaceae) family. The spindly red to purple branches grow from 30-60 centimeters (cm) (12-24 inches (in.)) long to 30 cm (12 in.) high, and may trail along the ground, arch upwards, or stand upright, often being supported by neighboring shrubs. Flowers are small (0.5 cm (0.2 in.)), pea-like, are found at the end of branches in clusters of 7-14 flowers, and have white petals that are tinged with purple. Fruits are boat-shaped (hence the common name “skiff” and the Latin name microcymbus meaning “small boat”), grow to less than 1 cm (0.4 in.), are triangular in cross-section, and hang abruptly downward from the branches

neighboring shrubs. Flowers are small (0.5 cm (0.2 in.)), pea-like, are found at the end of branches in clusters of 7-14 flowers, and have white petals that are tinged with purple. Fruits are boat-shaped (hence the common name “skiff” and the Latin name microcymbus meaning “small boat”), grow to less than 1 cm (0.4 in.), are triangular in cross-section, and hang abruptly downward from the branches. These characteristics, particularly the plant's diffuse branching, small white-purple pea-like flowers, and boat-like fruit pods distinguish this species from other Astragalus species in the area (description adapted from Peterson et al. 1981, pp. 5-7; Heil and Porter 1990, pp. 5-6; Isley 1998, p. 349).

Astragalus microcymbus was discovered in 1945 by Rupert Barneby roughly 6 kilometers (km) (4 miles (mi)) west of Gunnison, Colorado (Barneby 1949, pp. 499-500). The species was not located again until 1955 by the Colorado botanical expert William Weber, who originally considered it to be nonnative because of its dissimilarity to the other numerous Astragalus species in the region (Barneby 1964, p. 193). Both of these early collections were from alongside Highway 50 near Gunnison, Colorado, at a location that has likely been destroyed. The plant was not located in its more intact and native habitat along South Beaver Creek until Joseph Barrell rediscovered the species in 1966 (Barrell 1969, p. 284; Colorado Natural Heritage Program (CNHP) 2010a, p. 14).

The Astragalus genus is large, with over 1,500 species that are found on all continents except Antarctica and Australia, and with almost 600 species A. microcymbus is not similar in appearance to other Astragalus species in the region. Its presumed closest relative (from the Strigulosi section of Astragalus ) is found in New Mexico, with other relatives extending southward, and being found mostly in Mexico (Barneby 1964, p. 193; Isley 1998, pp. 349-350). The taxonomic status of A

nts except Antarctica and Australia, and with almost 600 species A. microcymbus is not similar in appearance to other Astragalus species in the region. Its presumed closest relative (from the Strigulosi section of Astragalus ) is found in New Mexico, with other relatives extending southward, and being found mostly in Mexico (Barneby 1964, p. 193; Isley 1998, pp. 349-350). The taxonomic status of A. microcymbus has not been disputed, although the monophyly (all members descended from a single common ancestor) of the Strigulosi section, and the placement of A. microcymbus within the section has been debated (Spellenberg 1974, pp. 394-395; Heil and Porter 1990, pp. 12-13). For the purposes of this finding, we consider A. microcymbus to represent a valid species and, therefore, a listable entity.

Biology and Life History

Astragalus microcymbus individuals live on average 2.2-3 years (with a range of 1-14 years). Most frequently, plants are alive for only 1 year (DePrenger-Levin 2010a, pers. comm.). The plant flowers from mid to late May into July (Heil and Porter 1990, p. 18; Japuntich 2010a, pers. comm.). There are more flowering plants in early June than at any other time, and flowering then drops off or stops, with a second bloom occurring in July (Japuntich 2010a, pers. comm.). The earlier flowering plants are reportedly larger and more vine-like, and later flowering plants are much smaller sized and less vine-like (Japuntich 2010a, pers. comm.).

Little is known of how Astragalus microcymbus reproduces. For example, we do not know if the plant requires pollinators, or what pollinators are important for reproduction. A single plant that was caged in 1980 did not produce fruit (Heil and Porter 1990, p. 18). Although this was suggested as evidence that the plant may require pollinators, we believe that this speculation is premature, because the study was completed for only one individual

reproduces. For example, we do not know if the plant requires pollinators, or what pollinators are important for reproduction. A single plant that was caged in 1980 did not produce fruit (Heil and Porter 1990, p. 18). Although this was suggested as evidence that the plant may require pollinators, we believe that this speculation is premature, because the study was completed for only one individual. Studies of other Astragalus species have found some species to be totally reliant on pollinators, and others to be somewhat self-compatible (able to produce seed without pollen from a different plant) but still relying on pollinators to some degree (Karron 1989, p. 337; Kaye 1999, p. 1254). Astragalus species with limited ranges are somewhat more self-compatible than wider ranging relatives (Karron 1989, p. 337).

Several pollinators have been observed visiting Astragalus microcymbus, suggesting that pollinators may be important for reproduction, but little is known about what pollinators these are (with the exception of the two listed below) and which are most important. Two insects that regularly visit the flowers of A. microcymbus were collected in 1989 (Heil and Porter 1990, pp. 18-19). One visitor was a small, black carpenter bee, Ceratina nanula that was collected from 3 sites (Heil and Porter 1990, pp. 18-19), and is known from at least 11 western States (Discover Life 2009, p. 1). The other visitor was a small, yellow and brown satyr butterfly, Coenonympha ochracea ssp. ochracea, a species of the Rocky Mountains (Heil and Porter 1990, p. 19). We expect there are more pollinators than these two species, based on the limited number of observations and collections to date (Heil and Porter 1990, pp. 6, 18-19; Sherwood 1994, p. 12), and because other Astragalus species are visited by many different pollinator species (Karron 1989, p. 322; Kaye 1999, pp. 1251-1252; Sugden 1985, p. 303)

es of the Rocky Mountains (Heil and Porter 1990, p. 19). We expect there are more pollinators than these two species, based on the limited number of observations and collections to date (Heil and Porter 1990, pp. 6, 18-19; Sherwood 1994, p. 12), and because other Astragalus species are visited by many different pollinator species (Karron 1989, p. 322; Kaye 1999, pp. 1251-1252; Sugden 1985, p. 303).

Fruits of Astragalus microcymbus have been observed as early as late-May, are always present by mid-June, with peak fruiting occurring in mid-July, and all fruits falling off the plants by late-August (Heil and Porter 1990, p. 18). Fruit production varies greatly. For example, during a life-history study (discussed in further detail in Distribution and Abundance below), no fruits were counted in 2002, and 33,819 fruits were counted in 2008 (Denver Botanic Gardens [DBG] 2010a, p. 5). In the same 14-year life history study (1995-2009), fruit production was high in only 3 years: 1995, 1997, and 2008 (DBG 2010a, p. 5). This type of synchronous seeding is sometimes referred to as mast seeding or mast years. Mast seedings may be a strategy to release enough seeds to feed seed predators, that are kept at lower numbers in years with little or no seed production, and still allow other seeds to germinate. Alternatively, it may be a product of increased pollination success (Crone and Lesica 2004, p. 1945). We are unsure of the conditions that lead to good seed and fruit set; overall annual precipitation does not explain the variability (DBG 2010a, p. 12).

Seed dispersal mechanisms have not been researched, but wind and rain are considered candidates (Heil and Porter 1990, p. 19). Seed dormancy, seed survival, and seed longevity in the soil are unknown. We do not know if specific cues ( e.g., temperature, precipitation, or seed coat alterations) are needed to break seed dormancy

al precipitation does not explain the variability (DBG 2010a, p. 12).

Seed dispersal mechanisms have not been researched, but wind and rain are considered candidates (Heil and Porter 1990, p. 19). Seed dormancy, seed survival, and seed longevity in the soil are unknown. We do not know if specific cues ( e.g., temperature, precipitation, or seed coat alterations) are needed to break seed dormancy. Seed bank studies for other Astragalus species indicate that the group generally possesses hard impermeable seed coats with a strong physical germination barrier. As a result, the seeds are generally long-lived in the soil, and only a small percentage of seeds germinate each year (summarized in Morris et al. 2002, p. 30). Conversely, the DBG looked at soil cores taken from A. microcymbus monitoring sites and found only one seed. The authors concluded that A. microcymbus does not have an active seed bank (DBG 2010a, p. 6). More research is needed to better understand the seed bank's role in the life history of the species.

Astragalus microcymbus individuals may exhibit prolonged dormancy (remaining underground throughout a growing season). This trait may help a species better cope with drought or resource-limiting conditions (Lesica and Steele 1994, pp. 209-210). Between 6 and 90 percent of A. microcymbus individuals are dormant in a given year (DBG 2008, pp. 6, 13, 18). Dormancy varies significantly from year to year and between plots (DBG 2010a, p. 15). Of the individuals that exhibited prolonged dormancy, 54 percent remained dormant for 1 year, 10 percent were dormant for 2 years, with a decreasing percentage of individuals remaining dormant for each successively longer time period to 11 years (DBG 2008, p. 6). These numbers for prolonged dormancy are not definitive because researchers are unable to say with certainty if a plant returning to a spot where an individual was previously found is a new individual or an individual returning from prolonged dormancy (DePrenger-Levin 2010a, pers. comm.)

centage of individuals remaining dormant for each successively longer time period to 11 years (DBG 2008, p. 6). These numbers for prolonged dormancy are not definitive because researchers are unable to say with certainty if a plant returning to a spot where an individual was previously found is a new individual or an individual returning from prolonged dormancy (DePrenger-Levin 2010a, pers. comm.).

Distribution and Abundance

We use several terms to discuss various sizes or groupings of Astragalus microcymbus individuals: Element Occurrence, site, polygon, point, and units. We consider the term Element Occurrence synonymous with population and it is further defined below. Within a population, various smaller “sites” have been hand drawn on maps between 1955 and 1994, and counted or tracked by site. To distinguish these older sites from more recent Global Positioning System (GPS) mapping efforts, we have used the term “polygon” (circles around clusters of individuals) or “point” (points representing one or a few plants within the immediate area) to describe data that was collected after 2003 with a GPS unit. Finally, we have taken the polygons and points and created “units” on which to conduct our spatial analyses for this 12-month finding. The

The CNHP, the agency that tracks rare plant species in the State of Colorado, operates within the national NatureServe network and follows NatureServe protocols. NatureServe guidelines on designating Element Occurrences state they are to be designated to best represent individual populations, and are typically separated from each other by barriers to movement or dispersal (NatureServe 2002, p. 11). The CNHP assigns overall species ranks for rare plants within the State of Colorado. Astragalus microcymbus has a Global rank of G1 indicating the species is critically imperiled across its range, and a State rank of S1 indicating the species is critically imperiled within the State of Colorado (CNHP 2010b, pp. 1, 5)

d from each other by barriers to movement or dispersal (NatureServe 2002, p. 11). The CNHP assigns overall species ranks for rare plants within the State of Colorado. Astragalus microcymbus has a Global rank of G1 indicating the species is critically imperiled across its range, and a State rank of S1 indicating the species is critically imperiled within the State of Colorado (CNHP 2010b, pp. 1, 5). Since the species is known only from the State of Colorado, the State (S) and Global (G) ranks are the same.

Astragalus microcymbus has a very limited range. It is found in an area roughly 5.6 km (3.5 mi) from east to west and 10 km (6 mi) from north to south with a small, disjunct (widely separated) population found 17 km (10.5 mi) to the southwest on Cebolla Creek (Figure 1). The species is known primarily from Gunnison County with one site located in Saguache County. The majority of sites and individuals are along South Beaver Creek just southwest of Gunnison, Colorado. The species occurs on lands managed by the Bureau of Land Management (BLM) Gunnison Resource Area and adjacent private lands. Within known areas, A. microcymbus has a spotty distribution, most likely linked to the habitat being spotty on the landscape (Heil and Porter 1990, p. 16). Using the highest counts across years and across all sites, we estimate the total maximum historic population to be around 20,500 individuals in 5 populations (Table 1; USFWS 2010a, pp. 1-4). However, more recent counts indicate there are substantially fewer individuals than this today (DBG 2010a, p. 7; BLM 2010, p. 3). We estimate A. microcymbus occupied roughly 34 hectares (ha) (83 acres (ac)) in 2008 (BLM 2010, pp. 8-10). In previous hand-drawn estimates, A. microcymbus occupied roughly 131 ha (324 ac) (CNHP 2010a).

BILLING CODE 4310-55-P EP15DE10.010 BILLING CODE 4310-55-C Table 1—Summary of Astragalus Microcymbus Populations (Element Occurrences) (USFWS 2010 a , pp. 1-4) Population name Population No

. 3). We estimate A. microcymbus occupied roughly 34 hectares (ha) (83 acres (ac)) in 2008 (BLM 2010, pp. 8-10). In previous hand-drawn estimates, A. microcymbus occupied roughly 131 ha (324 ac) (CNHP 2010a).

BILLING CODE 4310-55-P EP15DE10.010 BILLING CODE 4310-55-C Table 1—Summary of Astragalus Microcymbus Populations (Element Occurrences) (USFWS 2010 a , pp. 1-4) Population name Population No. Number of sites (pre-2004) Estimated number of individuals Ownership Population rank Beaver Creek SE 9 unknown 25 private Historic Henry 10 1 513 BLM B Gold Basin Creek 1 4 5,618 BLM A South Beaver Creek 2 39 14,317 BLM/private A Cebolla Creek none 1 unknown private C or D Total 45 20,473 Population rankings are categorized from A through D, with “A” ranked occurrences generally representing higher numbers of individuals and higher quality habitat, and “D” ranked occurrences generally representing lower numbers of individuals and lower quality (or degraded) habitat. A historic rank (H) indicates an occurrence that has not been visited for more than 20 years. The CNHP defines an Element Occurrence of Astragalus microcymbus as any naturally occurring population that is separated by a sufficient distance or barrier from a neighboring population. More specifically, for A. microcymbus, a population is separated by 1.6 km (1 mi) or more across unsuitable habitat, or 3.2 km (2 mi) across apparently suitable habitat (CNHP 2010b, p. 1). Given this definition, the CNHP has four populations of A. microcymbus in its database (CNHP 2010b, p. 2). Of these four populations, one (likely the type locality) has not been relocated since 1985 and is considered historic. This site was partially searched (because of private land access) in 1994 and not relocated, although there have not been subsequent visits. It is considered historic because it has not been seen in 20 years

s four populations of A. microcymbus in its database (CNHP 2010b, p. 2). Of these four populations, one (likely the type locality) has not been relocated since 1985 and is considered historic. This site was partially searched (because of private land access) in 1994 and not relocated, although there have not been subsequent visits. It is considered historic because it has not been seen in 20 years. The site along Cebolla Creek has not yet been incorporated into the CNHP's database, but when incorporated will comprise a separate population based on the separation distances described above.

While individuals of the species have been lost, we are unaware of the loss of any Astragalus microcymbus populations, although we are unsure of the status of Beaver Creek Southeast population. Two A. microcymbus populations comprise multiple sites (Gold Basin Creek and South Beaver Creek), and a few of these sites may have been extirpated (locally extinct). Site revisits using more accurate GPS mapping equipment from 2004-2008 generally re-located historical sites but decreased the overall footprint of most sites into smaller polygons and points. We roughly estimate the new mapping of polygons and points generally represents a reduction of about 75 percent in aerial extent from the original sites. We are unsure if the reduction of the site footprints is because of an actual contraction in the size of the sites, if the sites moved over time, or if it is an artifact of mapping efforts using improved technology. We expect it may be a combination of all three. At three sites in the South Beaver Creek area, no plants were re-located despite several survey efforts; these sites may have been extirpated (USFWS 2010a; pp. 1-4; BLM 2010, pp. 7-10; DePrenger-Levin 2010b, pers. comm.). In an extreme example, one site along South Beaver Creek (023-033-31975), was reduced from a larger 4-ha (10-ac) site to two small polygons that are 97 percent smaller than previously mapped (USFWS 2010a; pp. 1-4; BLM 2010, pp. 7-10)

s were re-located despite several survey efforts; these sites may have been extirpated (USFWS 2010a; pp. 1-4; BLM 2010, pp. 7-10; DePrenger-Levin 2010b, pers. comm.). In an extreme example, one site along South Beaver Creek (023-033-31975), was reduced from a larger 4-ha (10-ac) site to two small polygons that are 97 percent smaller than previously mapped (USFWS 2010a; pp. 1-4; BLM 2010, pp. 7-10).

The lumping of multiple sites into populations makes sense biologically because it generally represents areas where genetic exchange is possible (e.g., populations). However, past mapping efforts, site assessments, and count data have often been collected for smaller sites within a population (USFWS 2010a, pp. 1-4). The information gathered for these smaller sites is essential for tracking the status of the species but is somewhat problematic for an over-arching analysis for several reasons. First, the confusion between numbering protocols makes it difficult to ensure that particular counts, habitat specifics, or threats discussed by different sources are from the same sites. Second, mapping methodologies have resulted in varying delineations, especially with the advent of GPS technology.

For our analyses in this 12-month finding, we evaluated the sites, polygons, and points within Astragalus microcymbus populations, and created what we call units from which to conduct our analysis. We did this for several reasons: (1) To simplify the problems associated with tracking sites (i.e., different sources used different descriptors, making it difficult to ensure that they were talking about the same site); (2) to more broadly characterize and analyze the threats to the species' habitat (we believe that sites, polygons, and points are too fine scale); (3) because the polygons mapped in 2008 were on average much smaller than the original hand-drawn sites, we wanted to include more of the potential or previously occupied habitat rather than restricting our analysis to the 2008 mapped polygons; and (4) to provide for a more d

racterize and analyze the threats to the species' habitat (we believe that sites, polygons, and points are too fine scale); (3) because the polygons mapped in 2008 were on average much smaller than the original hand-drawn sites, we wanted to include more of the potential or previously occupied habitat rather than restricting our analysis to the 2008 mapped polygons; and (4) to provide for a more detailed analysis than would occur if we were to look at populations. To designate the units, we drew a perimeter around all GPS-derived polygons and points that were within 200 m (656 ft) of one another, and then buffered each perimeter by an additional 100 m (328 ft) (Figure 1; Table 2). This 100-m (328-ft) buffer was included so that previously occupied habitat, as drawn on maps, fell within the boundaries of these units. As a result of this exercise, all of the sites within the Gold Basin Creek population were lumped. As shown in Figure 1 above, this methodology divided the South Beaver Creek population into six separate units. The Beaver Creek Southeast population, located entirely on private land, is not included in our units because we are unsure of its exact location and current existence.

Table 2—Astragalus microcymbus Units for Our Spatial Analysis in This 12-Month Finding (USFWS 2010 a , pp. 1-4; 2010 b , pp. 1-3). Unit name Population No. Est. number of individuals Acres Hectares Ownership Beaver Creek SE 9 25 Unknown Unknown private Henry 10 513 10.8 4.4 BLM Gold Basin Creek 1 5,618 315.1 127.5 BLM South Beaver Creek 1 2 6,136 918.5 371.7 70% BLM, 30% private South Beaver Creek 2 2 3,667 684.5 277.0 68% BLM, 32% private South Beaver Creek 3 2 2,464 163.6 66.2 96% BLM, 4% private South Beaver Creek 4 2 778 24.1 9.75 70% BLM, 30% private South Beaver Creek 5 2 1,232 38.3 15.5 BLM South Beaver Creek 6 2 unknown 11.5 4.6 BLM Cebolla Creek none unknown 24.6 9.9 6% BLM, 94% private TOTAL 20,433* 2,190.8 886.6 75% BLM, 25% private *Number is different from Table 1 above because the counts from two historical sites

ivate South Beaver Creek 3 2 2,464 163.6 66.2 96% BLM, 4% private South Beaver Creek 4 2 778 24.1 9.75 70% BLM, 30% private South Beaver Creek 5 2 1,232 38.3 15.5 BLM South Beaver Creek 6 2 unknown 11.5 4.6 BLM Cebolla Creek none unknown 24.6 9.9 6% BLM, 94% private TOTAL 20,433* 2,190.8 886.6 75% BLM, 25% private *Number is different from Table 1 above because the counts from two historical sites were excluded from the units. Comprehensive surveys for Astragalus microcymbus were conducted in 1989 (BLM 1989a, pp. 1-31) and 1994 (Sherwood 1994, pp. 1-24). In 2008, the BLM conducted a comprehensive mapping effort without counts or population assessments (BLM 2010, p. 3). Several other efforts have counted individuals within certain sites (Japuntich 2010b, pers. comm.; DePrenger-Levin 2010b, pers. comm.; 2010c, pers. comm.; 2010d, pers. comm.; USFWS 2010a, pp. 1-4). Count data from various sites are difficult to compare because there is no way of knowing if two observers, during different years, travelled across similar areas, and if the effort between the two counts were similar. In general, counts in 1994 were higher than 1989 (Sherwood 1994, p. 13; USFWS 2010a, pp. 1-4). Several other observers have subsequently returned to these sites and found that A. microcymbus numbers in 2004, 2005, 2007, and 2008 were much lower than those of 1994 and the 1980s, with many sites shrinking from thousands to hundreds of individuals (DBG 2010a, p. 7; BLM 2010, p. 3; USFWS 2010a, pp. 1-4). Site counts and estimates from the 1980s and 1990s often reported the number of A. microcymbus individuals as more than 500, and sometimes as more than 2,000 individuals. Most counts in the last 5 years have been far less, generally under 150 individuals with only 1 count over 400 individuals (USFWS 2010a, pp. 1-4).

In 1989, the BLM developed a protocol to provide long-term trend data for selected populations of Astragalus microcymbus (BLM 1989b, pp. 1-4). They applied the protocol in select locations in 1990, 1994, and 2008

etimes as more than 2,000 individuals. Most counts in the last 5 years have been far less, generally under 150 individuals with only 1 count over 400 individuals (USFWS 2010a, pp. 1-4).

In 1989, the BLM developed a protocol to provide long-term trend data for selected populations of Astragalus microcymbus (BLM 1989b, pp. 1-4). They applied the protocol in select locations in 1990, 1994, and 2008. The number of individuals between 1990 and 2008 was not statistically different, and both years had similar low annual precipitation (20 cm (8 in.)) compared to the average of 25 cm (10 in.) (USFWS 2010c, pp. 1-8; DBG 2010a, p. 12; Western Regional Climate Center [WRCC] 2010a, pp. 1-8). However, there were significantly more plants in 1994 (three to four times) than either 1990 or 2008. Precipitation was higher in 1994, roughly 10 cm (4 in.) more than in 1990 or 2008 (USFWS 2010c, pp. 1-8). We conclude that there are more above-ground plants in years with more precipitation.

The DBG has been monitoring Astragalus microcymbus annually since 1995 (Carpenter 1995, pp. 1-7; DBG 2003, pp. 1-23; 2007, pp. 1-16; 2008, pp. 1-20; 2010a, pp. 1-17). The DBG found a decline in the number of A. microcymbus individuals from 1995-2009 (Figure 2), especially from 1995-2002 (DBG 2010a, p. 5). When comparing the first year of monitoring to the last, this decline is not statistically significant because of a partial rebound in the last few years (DBG 2010a, pp. 5, 10-11). This decline is apparent, although not significant, when considering only above-ground individuals (p = 0.11) as well as when combining above-ground individuals with dormant individuals (p = 0.19) (Figure 2). Dormant individuals are unknown for the first and last years of the study (1995 and 2008) because of problems associated with finding dormant individuals in the first year, and because dormant individuals cannot be distinguished from dead individuals in the last year

ove-ground individuals (p = 0.11) as well as when combining above-ground individuals with dormant individuals (p = 0.19) (Figure 2). Dormant individuals are unknown for the first and last years of the study (1995 and 2008) because of problems associated with finding dormant individuals in the first year, and because dormant individuals cannot be distinguished from dead individuals in the last year.

BILLING CODE 4310-55-P EP15DE10.011 BILLING CODE 4310-55-C In conjunction with the life-history monitoring, the DBG conducted a population viability analysis using data from 1995-2006. They found that all monitored populations of Astragalus microcymbus were in rapid decline, and predicted that all populations will comprise 20 individuals or less—their definition of extinct—by 2030 (DBG 2010a, p. 10). This analysis has not been updated incorporating more recent monitoring data. However, a preliminary review for a subsequent population viability analysis has found still declining trends but with a more gradual decline that would likely delay the predicted extinction date (DePrenger-Levin 2010e, pers. comm.). Unfortunately, the population viability analysis including the 2007 and 2008 data has not been completed. The 2009 data cannot be used because of the problems associated with identifying dead or dormant individuals.

Astragalus microcymbus numbers are positively correlated with precipitation. In a statistical comparison, annual rainfall from August of the previous growing season to July of the current growing season positively influenced the number of A. microcymbus individuals, average maximum temperature in May and July negatively influenced the number of individuals, and rainfall in May and July positively influenced the number of individuals significantly (DBG 2010a, p. 6). In addition, rainfall in springtime months during the growing season was statistically correlated with more above-ground growth (DBG 2010a, p. 6)

nfluenced the number of A. microcymbus individuals, average maximum temperature in May and July negatively influenced the number of individuals, and rainfall in May and July positively influenced the number of individuals significantly (DBG 2010a, p. 6). In addition, rainfall in springtime months during the growing season was statistically correlated with more above-ground growth (DBG 2010a, p. 6).

Survey efforts, trend monitoring, life-history monitoring, and the corresponding population viability analysis all suggest that Astragalus microcymbus numbers are declining. In both of the more rigorous monitoring efforts, the decline seems to be correlated with precipitation. The drought in the early 2000s caused a huge decline in numbers, with a rebound in the later 2000s (DBG 2010a, p. 5). However, the very low survey numbers from this decade as compared to the 1980s and 1990s seem less correlated with precipitation (USFWS 2010a, pp. 1-4; WRCC 2010a, pp. 1-8). The reasons for these declines are not fully understood.

Habitat

Astragalus microcymbus is found in the sagebrush steppe ecosystem at elevations of 2,377-2,597 meters (m) (7,800-8,520 feet (ft)). The plant is most commonly found on rocky or cobbly, moderate to steep (9-38 degrees) slopes of hills and draws (Heil and Porter 1990, p. 16), although there are some sites that are flat. Plants are generally found on southeast to southwest aspects, but are occasionally found on northern exposures (Heil and Porter 1990, p. 13). The average annual precipitation is around 25 cm (10 in.) a year, and is fairly consistently spread across the year, except for July and August when roughly twice the precipitation falls compared to the other months (WRCC 2010b, pp. 3, 8). Snow falls in the winter and remains on the ground from November/December through March/April (WRCC 2010a, pp. 3, 8). Winters are cold with an average daily high in January of -3 °C (26.5 °F) and an average daily low of -20 °C (-4.0 °F). Summers are warmer

ead across the year, except for July and August when roughly twice the precipitation falls compared to the other months (WRCC 2010b, pp. 3, 8). Snow falls in the winter and remains on the ground from November/December through March/April (WRCC 2010a, pp. 3, 8). Winters are cold with an average daily high in January of -3 °C (26.5 °F) and an average daily low of -20 °C (-4.0 °F). Summers are warmer. July is the hottest month with an average daily high of 27 °C (81 °F) and an average daily low of 6 °C (44 °F) (WRCC 2010b, pp. 3-8).

Astragalus microcymbus is found in open park-like landscapes dominated by several sagebrush species, cacti, sparse grasses, and other scattered shrubs. Shrubs are primarily represented by Artemisia tridentata ssp. vaseyana (mountain big sagebrush), Artemisia tridentata ssp. wyomingensis (Wyoming sagebrush), Artemisia frigida (fringed sagebrush or prairie sagewort), and Artemisia nova (black sagebrush); cacti include Yucca harrimaniae (Spanish bayonet) , and Opuntia polyacantha (plains pricklypear); grasses most commonly include Achnatherum hymenoides (formerly Oryzopsis hymenoides —Indian ricegrass) , Elymus elymoides (formerly Sitanion hystrix —squirreltail), Hesperostipa comata (formerly Stipa comata —needle and thread grass), and Poa sp. (fescue); and the most common forbs include Cryptantha cinerea (James' Cryptantha) Penstemon teucrioides (germander beardtongue). Other shrubs and small trees found within A. microcymbus' habitat include Ribes cereum (wax currant), Symphoricarpos oreophilus (mountain snowberry), and Juniperus scopulorum (Rocky Mountain juniper).

Soils are well drained and vary from sandy to rocky, but are primarily a thin cobble-clay loam (Heil and Porter 1990, p. 13)

nerea (James' Cryptantha) Penstemon teucrioides (germander beardtongue). Other shrubs and small trees found within A. microcymbus' habitat include Ribes cereum (wax currant), Symphoricarpos oreophilus (mountain snowberry), and Juniperus scopulorum (Rocky Mountain juniper).

Soils are well drained and vary from sandy to rocky, but are primarily a thin cobble-clay loam (Heil and Porter 1990, p. 13). The primary soils within Astragalus microcymbus units are stony rock land (46 percent), Lucky-Cheadle gravelly sandy loams with 5-45 percent slopes (39 percent), alluvial land (8 percent), and Kezar-Cathedral gravelly sandy loams with 5-35 percent slopes (4 percent) (Natural Resource Conservation Service (NRCS) 2008; USFWS 2010b, pp. 12-13). Geologically, A. microcymbus is associated with: (1) Felsic and hornblendic gneiss (metamorphic from igneous) substrates; (2) granitic (igneous) rocks of 1,700 million-year age group; and (3) biotitic gneiss, schist, and migmatite (sedimentary) substrates with 52, 37, and 11 percent, respectively, in each geology (Knepper et al. 1999, pp. 21-22; USFWS 2010b, pp. 10-11).

The areas where Astragalus microcymbus is found are generally distinct from surrounding habitats. They are more sparsely vegetated, drier than surrounding areas, more heavily occupied by cacti, and appear to have some specific soil properties as described above. This habitat is limited and patchily distributed on the landscape.

Summary of Information Pertaining to the Five Factors

Section 4 of the Act (16 U.S.C. 1533) and implementing regulations (50 CFR 424) set forth procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants

cupied by cacti, and appear to have some specific soil properties as described above. This habitat is limited and patchily distributed on the landscape.

Summary of Information Pertaining to the Five Factors

Section 4 of the Act (16 U.S.C. 1533) and implementing regulations (50 CFR 424) set forth procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of the Act, a species may be determined to be endangered or threatened based on any of the following five factors:

(A) The present or threatened destruction, modification, or curtailment of its habitat or range;

(B) Overutilization for commercial, recreational, scientific, or educational purposes;

(C) Disease or predation;

(D) The inadequacy of existing regulatory mechanisms; or

(E) Other natural or manmade factors affecting its continued existence.

In making this 12-month finding, we evaluated the best scientific and commercial information available. Our evaluation of this information is presented below.

In considering what factors might constitute threats to a species, we must look beyond the exposure of the species to a factor to evaluate whether the species may respond to the factor in a way that causes actual impacts to the species. If there is exposure to a factor and the species responds negatively, the factor may be a threat and we attempt to determine how significant a threat it is. The threat is significant if it drives, or contributes to, the risk of extinction of the species such that the species warrants listing as endangered or threatened as those terms are defined in the Act.

Factor A

ctual impacts to the species. If there is exposure to a factor and the species responds negatively, the factor may be a threat and we attempt to determine how significant a threat it is. The threat is significant if it drives, or contributes to, the risk of extinction of the species such that the species warrants listing as endangered or threatened as those terms are defined in the Act.

Factor A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range

The following potential factors that may affect the habitat or range of Astragalus microcymbus are discussed in this section, including: (1) Residential and urban development; (2) recreation, roads, and trails; (3) utility corridors; (4) nonnative invasive plants; (5) wildfire; (6) contour plowing and nonnative seedings; (7) livestock, deer and elk use of habitat; (8) mining, oil and gas leasing; (9) climate change; and (10) habitat fragmentation and degradation.

Residential and Urban Development

The majority of Astragalus microcymbus is located between 3.2 and 11 km (2 and 7 mi) of the town of Gunnison, Colorado, the largest town in Gunnison County (Figure 1). Rapid population growth in the rural Rocky Mountains, including the Gunnison area, is being driven by the availability of natural amenities, recreational opportunities, aesthetically desirable settings, grandiose viewscapes, and perceived remoteness (Riebsame 1996, pp. 396, 402; Theobald et al. 1996, p. 408; Gosnell and Travis 2005, pp. 192-197; Mitchell et al. 2002, p. 6; Hansen et al. 2005, pp. 1899-1901). Gunnison County grew from 5,477 people in 1960 to 15,048 people in 2007, constituting a 300 percent increase in population in less than 50 years (CensusScope 2010, pp. 1-3; Colorado State Demography Office 2008, p. 1). The population of Gunnison County is predicted to more than double by 2050 to approximately 31,100 residents (Colorado Water Conservation Board 2009, p. 53)

l. 2005, pp. 1899-1901). Gunnison County grew from 5,477 people in 1960 to 15,048 people in 2007, constituting a 300 percent increase in population in less than 50 years (CensusScope 2010, pp. 1-3; Colorado State Demography Office 2008, p. 1). The population of Gunnison County is predicted to more than double by 2050 to approximately 31,100 residents (Colorado Water Conservation Board 2009, p. 53).

Human population growth results in increased fragmentation of habitat ( see Factor E below) (Theobald et al. 1996, pp. 410-412), increased recreation and more roads ( see Recreation, Roads, and Trails below) (Mitchell et al. 2002, pp. 5-6; Hansen et al. 2005, p. 1899), more utility corridors (see Utility Corridors below), more nonnative invasive plants (see Nonnative Invasive Plants below) (Hansen et al. 2005, p. 1896), and changes to ecological processes (Hansen et al. 2005, p. 1901). A recent but common pattern of population growth in the Gunnison area is “exurban” or “ranchette” development. These ranchettes consist of larger lots (generally more than 14 ha (35 ac)) each with an isolated large house. This type of development, because of its location outside of urban footprints, may have more impacts to ecosystems and biodiversity than urban or urban fringe development (Hansen et al. 2005, p. 1903). Much of this development occurs on steeper slopes, like those where Astragalus microcymbus is found, where views are better.

To the best of our knowledge, residential and urban development (aside from roads) has impacted only one Astragalus microcymbus unit: the Beaver Creek Southeast Unit. The original type locality along Highway 50 may have been lost to highway activities, and the nearby private lands where the plant was located in the late 1970s and early 1980s may have been lost to a gravel pit (Sherwood 1994, pp. 18-19). No more than 30 plants were reported from this unit in any given year from 1955-1994 (USFWS 2010a, p. 1). Only two A

mbus unit: the Beaver Creek Southeast Unit. The original type locality along Highway 50 may have been lost to highway activities, and the nearby private lands where the plant was located in the late 1970s and early 1980s may have been lost to a gravel pit (Sherwood 1994, pp. 18-19). No more than 30 plants were reported from this unit in any given year from 1955-1994 (USFWS 2010a, p. 1). Only two A. microcymbus sites are near buildings: There is a cabin near one of the larger A. microcymbus sites within the South Beaver Creek 1 Unit (BLM 1989a, p. 31), and there is a house within the Cebolla Creek Unit. We do not know if construction of either of these structures impacted A. microcymbus.

Twenty-five percent of the Astragalus microcymbus units are on private land, mostly along South Beaver Creek (Table 2). Five parcels of private land (with an additional parcel nearby) are currently within A. microcymbus units along South Beaver Creek ranging in size from 17 to 263 ha (43 to 650 ac), only one of which has any housing or agricultural developments. All of these parcels are used primarily for livestock ranching operations that have a much lower impact than urban or residential development.

These private land parcels bisect the South Beaver Creek 1 and South Beaver Creek 2 Units, and clip portions of the South Beaver Creek 3 and South Beaver Creek 4 Units (USFWS 2010b, pp. 2-3). Roughly half of the known Astragalus microcymbus individuals are within the South Beaver Creek 1, 2, and 4 Units (Table 2), making them especially important to the conservation of the species. These three units all have at least 30 percent of their area on private

Residential or urban development of these parcels would likely lead to the destruction of Astragalus microcymbus individuals, as well as fragment and alter the plants' habitat. In 2005, it was estimated that only 30 percent of the private lands in Gunnison County remained undeveloped (Gunnison County 2005, p. 1)

the species. These three units all have at least 30 percent of their area on private

Residential or urban development of these parcels would likely lead to the destruction of Astragalus microcymbus individuals, as well as fragment and alter the plants' habitat. In 2005, it was estimated that only 30 percent of the private lands in Gunnison County remained undeveloped (Gunnison County 2005, p. 1). Because only 30 percent of the private lands in Gunnison County remain undeveloped, and because the population of Gunnison County is expected to double by 2050, we conclude that the currently undeveloped private lands where A. microcymbus occurs are likely to be developed by 2050. The potential loss of up to 25 percent of the area (habitat) and even more of the individuals of A. microcymbus is a significant threat for a species with such limited numbers and a limited range (Table 2). This development also would fragment the habitat, potentially isolating small populations from one another leading to the further loss of individuals.

Currently, the impact of development on the species is relatively minor, consisting of the few examples provided above. Although 25 percent of Astragalus microcymbus individuals are on private lands with no protective mechanisms in place for the species, little development is currently occurring on these private lands. However, we believe that the threat of development to the species may increase in the foreseeable future based on future human population growth. Future development on these lands is likely, because of the rate of growth in the Gunnison area. Given that Gunnison County has seen a 300 percent increase in population in less than 50 years, that only 30 percent of the private lands remain undeveloped, and A. microcymbus' close proximity to the town of Gunnison, we expect that some of these private land parcels will be developed in the next several decades

lopment on these lands is likely, because of the rate of growth in the Gunnison area. Given that Gunnison County has seen a 300 percent increase in population in less than 50 years, that only 30 percent of the private lands remain undeveloped, and A. microcymbus' close proximity to the town of Gunnison, we expect that some of these private land parcels will be developed in the next several decades. Based on the population projections presented above, the foreseeable future for development is 40 years, as the population of Gunnison County is predicted to more than double by 2050. Based on the above information, we consider residential and urban development to be a threat to the species in the foreseeable future.

Recreation, Roads, and Trails

It is difficult to separate the effects of roads and trails from the effects of recreation where Astragalus microcymbus resides. Most forms of recreation within A. microcymbus' range include the use of roads and trails either as a form of recreation ( e.g., vehicle use, mountain biking, or hiking) or as a way to access recreation areas ( e.g., target shooting and rock climbing areas). For these reasons, we have chosen to address recreation, roads, and trails together in this section.

Roads cause habitat fragmentation because they create abrupt transitions in vegetation; add edge to adjacent patches; are sources of pollutants; and act as filters (allowing some species to cross but not others) and barriers (prohibiting movement) (Spellerberg 1998, pp. 317-333). Road networks contribute to exotic plant invasions via introduced road fill, vehicle transport of plant parts, and road maintenance activities (Forman and Alexander 1998, p. 210; Forman 2000, p. 32; Gelbard and Belnap 2003, p. 426). Many of these invasive species are not limited to roadsides, but also encroach into surrounding habitats (Forman and Alexander 1998, p. 210; Forman 2000, p. 33; Gelbard and Belnap 2003, p. 427)

o exotic plant invasions via introduced road fill, vehicle transport of plant parts, and road maintenance activities (Forman and Alexander 1998, p. 210; Forman 2000, p. 32; Gelbard and Belnap 2003, p. 426). Many of these invasive species are not limited to roadsides, but also encroach into surrounding habitats (Forman and Alexander 1998, p. 210; Forman 2000, p. 33; Gelbard and Belnap 2003, p. 427).

Aside from the indirect effects discussed above, a road typically removes all vegetation from about 0.7 ha (1.7 ac) per 1.6 km (1 mi), while a single track trail removes all vegetation from about 0.1 ha (0.25 ac) per 1.6 km (1 mi) (BLM 2005a, p. 13). Roads also act as corridors that facilitate human interaction with species and increase the opportunities and the likelihood of travel across undisturbed (non-road) areas. The recreational use of roads is on the rise. From 1991 to 2006, off-highway vehicle registrations increased 937 percent (from 11,744 to 109,994 within the state), with an average annual increase of 16 percent (Summit County Off Road Riders 2009, p. 1). Recreational activities within the Gunnison Basin are widespread, occur during all seasons of the year (especially summer and hunting season), and have expanded as more people move to the area or come to recreate (BLM 2009a, pp. 7-8). Motorized and mechanized use has been increasing within the Gunnison Basin and is expected to increase in the future based on increased population (USFS and BLM 2010, pp. 5, 9, 85, 124-125, 136, 158, 177, 204, 244, 254, 269, 278).

Because Astragalus microcymbus generally occurs on slopes, it is somewhat protected from the further development of large roads. And many of the existing roads, although not all, run immediately along the bottom or top of sites instead of through the middle of sites. However, these slopes appear to be the preferred location for dirt bike and mountain bike trails, especially those that were user-created instead of formally designed. Many of the trails within the range of A

otected from the further development of large roads. And many of the existing roads, although not all, run immediately along the bottom or top of sites instead of through the middle of sites. However, these slopes appear to be the preferred location for dirt bike and mountain bike trails, especially those that were user-created instead of formally designed. Many of the trails within the range of A. microcymbus are user-created and run across or up through the slopes where the plant is found (USFWS 2010, pers. comm.). These user-created trails, when redesigned, often require a series of switchbacks, which could increase the opportunity for impacts to the plant. Travel management (the allocation and utilization of motorized and nonmotorized use), and route designation and design, both within the Hartman Rocks Recreation Area and outside that area, are described in further detail below.

Except for the one disjunct population, all of the Astragalus microcymbus units are within 11 km (7 mi) of the town of Gunnison, the closest of which is 3.2 km (2 mi) away. This close proximity to an urban area makes the species more susceptible to recreational impacts than if it were located more remotely. The Hartman Rocks Recreation Area is a popular urban interface recreation area and contains roughly 40 percent of the A. microcymbus units (BLM 2005a, p. 3; USFWS 2010b, pp. 4-5). The Hartman Rocks Recreation Area is located between 3 and 10 km (2 and 6 mi) from the town of Gunnison on BLM lands (BLM 2005a, p. 3). The Hartman Rocks Recreation Area covers 3,380 ha (8,350 ac), but trails expand out onto adjacent lands. These lands also have A. microcymbus plants and habitat that are being impacted by these trails (BLM 2005a, p. 3).

We have no detailed information on how much use occurs, how this use is increasing, or when the use is occurring in the Hartman Rocks Recreation Area. In 2005, it was estimated that the Hartman Rocks Recreation Area received 15,000-20,000 user days each year (BLM 2005a, p. 3)

ss use in the winter and early spring when trails are snow covered or muddy. Closures during A. microcymbus' growing season (likely late April through August) would benefit the species by reducing impacts to seedlings and plants, and by lessening disruptions to pollinators. The Aberdeen Loop trail that runs through the South Beaver Creek 1, South Beaver Creek 5, and South Beaver Creek 6 occupied A. microcymbus habitat is subject to seasonal closures for the Gunnison sage grouse from June 15 until August 31. This closure provides partial protection for A. microcymbus in the growing season.

The South Beaver Creek Area of Critical Environmental Concern (ACEC) (also a Colorado Natural Area) was designated in 1993 by the BLM with the intent of protecting and enhancing existing populations of Astragalus microcymbus (BLM 1993, pp. 2.18, 2.29; Colorado Natural Areas Program [CNAP] 1997, pp. 1-7). The South Beaver Creek ACEC is 1,847 ha (4,565 ac), and includes 60 percent of the A. microcymbus units rangewide (BLM 1993, p. 2.18; USFWS 2010b, pp. 8-9). Seventy percent of the South Beaver Creek ACEC is within the Hartman Rocks Recreation Area, although the South Beaver Creek ACEC was developed at least 8 years prior to the Hartman Rocks Recreation Area (BLM 2005a, p. 44). Because of its designation as a recreation area, the Hartman Rocks Recreation Area draws users to the area, which is in conflict with the ACEC's intent to protect and enhance A. microcymbus.

When the South Beaver Creek ACEC was designated, motorized vehicle traffic was limited to designated routes, whereas it had previously been open on all lands (BLM 1993, p. 2.30). Outside the South Beaver Creek ACEC, all lands within the range of Astragalus microcymbus remained open to motorized vehicle traffic. In 2001, mechanized travel, including mountain bikes, on all lands within the Gunnison Resource Area including the South Beaver Creek ACEC and the Hartman Rocks Recreation Area was limited to designated routes (U.S. Forest Service (USFS) and BLM 2001a, p

, p. 2.30). Outside the South Beaver Creek ACEC, all lands within the range of Astragalus microcymbus remained open to motorized vehicle traffic. In 2001, mechanized travel, including mountain bikes, on all lands within the Gunnison Resource Area including the South Beaver Creek ACEC and the Hartman Rocks Recreation Area was limited to designated routes (U.S. Forest Service (USFS) and BLM 2001a, p. 3; 2001b, pp. 1-2; BLM 2005a, p. 14). This closure resulted in new protections for A. microcymbus from mountain bikes and vehicular use on BLM lands outside the South Beaver Creek ACEC, and from mountain bikes within the ACEC.

Enforcement of travel designations and trail closures is difficult given the large area of the BLM's Gunnison Resource Area and limited law enforcement personnel (USFS and BLM 2010, p. 259). Illegal trails are always an issue in well-used recreation areas (BLM 2010, p. 4). Furthermore, the open park-like habitat of Astragalus microcymbus makes it difficult to disguise trails that have been closed. Numerous undesignated trails running through A. microcymbus habitat are visible on satellite images ( see below). Law enforcement with the Gunnison Resource Area is provided by the BLM's Montrose Area Office, which is located over 105 km (65 mi) away. Law enforcement within this area is intermittent, and tickets are rarely, if ever, issued for trespass use (USFS and BLM 2010, p. 259).

As an example, the Quarry Drop trail that runs through the South Beaver Creek 1 Unit was closed in 2005 with the Hartman Rocks Recreation Plan, because it ran directly through two Astragalus microcymbus sites (BLM 2010, p. 4). Although this trail is posted as closed, it was still in use during the summer of 2009, when rocks were placed to close the trail entrance (BLM 2010, p. 4). The Gunnison Trails group (a local non-profit trail-building group) and the BLM have increased their efforts on finding illegal trails and closing them before they become more established

ough two Astragalus microcymbus sites (BLM 2010, p. 4). Although this trail is posted as closed, it was still in use during the summer of 2009, when rocks were placed to close the trail entrance (BLM 2010, p. 4). The Gunnison Trails group (a local non-profit trail-building group) and the BLM have increased their efforts on finding illegal trails and closing them before they become more established. Continued pressure from the recreation community for new trail construction is likely, as well as trespass use (BLM 2010, p. 4). In an effort to control illegal use, the BLM has put up educational signs where roads enter the South Beaver Creek ACEC explaining what A. microcymbus is and why the species and its habitat are important to preserve (BLM 2010, p. 6). Trails that have been closed are planned to be rehabilitated where they meet open trails during the summer of 2011 in an attempt to ensure they will no longer be used (Japuntich 2010d, pers. comm.).

The BLM and the USFS finalized a joint Environmental Impact Statement for a Gunnison Basin Federal Lands Travel Management Plan that includes areas on BLM lands outside the Hartman Rocks Recreation Area (USFS and BLM 2010, pp. 1-288). This plan builds upon the Gunnison Travel Interim Restrictions of 2001 by closing additional routes, mostly for resource-related reasons (USFS and BLM 2010, p. 1). Astragalus microcymbus is not considered in detail in this plan, nor does the plan designate roads be closed specifically to protect A. microcymbus (USFS and BLM 2010, pp. 47, 78-79). None of the closures proposed in the plan will benefit A. microcymbus nor do they address routes within the Hartman Rocks Recreation Area.

We have found roads, trails, and gravel parking areas atop Astragalus microcymbus individuals and polygons (USFWS 2010, pers. comm.). These roads, trails, and parking areas have no vegetation. A. microcymbus individuals can be found along the margins of these roads, trails, and parking areas, sometimes with tire tracks atop (USFWS 2010, pers. comm.)

utes within the Hartman Rocks Recreation Area.

We have found roads, trails, and gravel parking areas atop Astragalus microcymbus individuals and polygons (USFWS 2010, pers. comm.). These roads, trails, and parking areas have no vegetation. A. microcymbus individuals can be found along the margins of these roads, trails, and parking areas, sometimes with tire tracks atop (USFWS 2010, pers. comm.). Cheatgrass is spreading from the old road bed upslope and into the one site where invasion is occurring (USFWS 2010, pers. comm.). Trails sometimes are deeply incised and eroded (USFWS 2010, pers. comm.).

We conducted a spatial analysis overlaying the distribution of Astragalus microcymbus units with designated routes within and near the Hartman Rocks Recreation Area. We found 8.8 km (5.5 mi) of roads (3.5 km (2.3 mi)) and trails (5.3 km (3.2 mi)) overlap with A. microcymbus units (Table 3) (BLM 2010; USFWS 2010b, pp. 14-15). Through this mapping effort, we found four of the polygons within the Gold Basin Creek Unit are being directly impacted by these roads and trails (USFWS 2010b, p. 16). We also are aware of at least three other polygons that are being directly impacted by roads and trails (USFWS 2010, pers. comm.). Estimating that a road typically removes all vegetation from about 0.7 ha (1.7 ac) per 1.6 km (1 mi) while a single track trail removes all vegetation from about 0.1 ha (0.25 ac) per 1.6 km (1 mi) (BLM 2005a, p. 13), designated roads directly impact 1.6 ha (3.9 ac) and designated trails directly impact 0.3 ha (0.8 ac) of habitat within A. microcymbus units

ads and trails (USFWS 2010, pers. comm.). Estimating that a road typically removes all vegetation from about 0.7 ha (1.7 ac) per 1.6 km (1 mi) while a single track trail removes all vegetation from about 0.1 ha (0.25 ac) per 1.6 km (1 mi) (BLM 2005a, p. 13), designated roads directly impact 1.6 ha (3.9 ac) and designated trails directly impact 0.3 ha (0.8 ac) of habitat within A. microcymbus units.

Table 3—Roads, Trails, and Paths Within Astragalus microcymbus Units [Designated routes are those included in the BLM's geospatial layers, undesignated are those located using satellite imagery] Unit name Designated Roads km (mi) Trails km (mi) Undesignated Roads km (mi) Trails km (mi) Paths km (mi) Total km (mi) Henry 0.1 (0.06) 0.1 (0.06) 0.1 (0.06) 0.3 (0.2) Gold Basin Creek 2.2 (1.4) 1.4 (0.9) 0.1 (0.06) 0.4 (0.2) 1.3 (0.8) 5.4 (3.4) South Beaver Creek 1 1.2 (0.7) 3.5 (2.2) 6.3 (3.9) 3.4 (2.1) 1.6 (1.0) 16.0 (9.9) South Beaver Creek 2 2.4 (1.5) 0.3 (0.2) 3.6 (2.2) 6.3 (3.9) South Beaver Creek 3 0.7 (0.4) 0.7 (0.4) South Beaver Creek 4 South Beaver Creek 5 0.2 (0.1) 0.2 (0.1) South Beaver Creek 6 0.2 (0.1) 0.2 (0.1) Cebolla Creek 0.6 (0.4) 0.6 (0.4) Total (km) 3.5 (2.2) 5.3 (3.3) 10.2 (6.4) 4.2 (2.6) 6.5 (4.0) 29.7 (18.5) While travel is officially limited to designated routes only on BLM lands, there are numerous roads, trails, and paths that are not designated, with some receiving regular use. Some of these roads have been closed, but their footprint remains. Some of these roads are on private lands along South Beaver Creek, but many are trails or old roads on BLM lands that are undesignated, that either show evidence of use or could be receiving use. We used the NRCS' 2005 National Agriculture Imagery Program satellite imagery to look for roads, trails, and paths in occupied Astragalus microcymbus units additional to those BLM roads and trails included in the analysis above. We designated roads, trails, and paths based on the width of the disturbance

n BLM lands that are undesignated, that either show evidence of use or could be receiving use. We used the NRCS' 2005 National Agriculture Imagery Program satellite imagery to look for roads, trails, and paths in occupied Astragalus microcymbus units additional to those BLM roads and trails included in the analysis above. We designated roads, trails, and paths based on the width of the disturbance. Roads were the widest, trails were narrower, and paths were the narrowest. We found almost 21 km (13 mi) of additional roads, trails, and paths, including: 10.2 km (6.3 mi) of roads, 4.2 km (2.6 mi) of trails, 6.5 km (4.0 mi) of paths (Table 3) (USFWS 2010b, pp. 21-22). Using the BLM's estimates of direct impacts (BLM 2005a, p. 13), undesignated roads directly impact 4.4 ha (10.9 ac), undesignated trails directly impact 0.3 ha (0.8 ac), and undesignated paths directly impact less than 0.4 ha (1 ac) of A. microcymbus habitat. Because we were using satellite imagery, we cannot say for certain what the level of use is on the trails, or even say if they are still in use. Some of the paths may have been livestock trails. Livestock trails may receive more or less use than other trails, but the effects are likely similar.

All units except the South Beaver Creek 4 Unit have roads and trails. Designated and undesignated roads denude about 5.7 ha (14.1 ac), designated and undesignated trails denude about 0.6 ha (1.6 ac), and undesignated paths denude less than 0.4 ha (1 ac) within Astragalus microcymbus units, or less than 0.8 percent (Table 4). To estimate the indirect effects of roads and trails, we used a 20-m (66-ft) buffer on either side of roads and trails. This distance represents the area where invasive nonnative species are most likely to invade, pollinators may be impacted or disturbed by passing vehicles, off-trail use is most likely, and impacts from dust may occur. This distance results in a conservative estimate of impacts, as it is probably more accurate for trails than roads (summarized in DBG 2010b, p. 1)

n either side of roads and trails. This distance represents the area where invasive nonnative species are most likely to invade, pollinators may be impacted or disturbed by passing vehicles, off-trail use is most likely, and impacts from dust may occur. This distance results in a conservative estimate of impacts, as it is probably more accurate for trails than roads (summarized in DBG 2010b, p. 1). Using this buffer distance, we estimate that roughly 14.5 percent of A. microcymbus' total habitat may currently be impacted by roads and trails (Table 4) (USFWS 2010b, pp. 23-25). We expect our 15-percent estimate is low. For example, plumes of dust are known to travel hundreds of meters, especially in arid climates (Gilles et al. 2005, p. 2346). Also, we expect that the two known pollinators of A. microcymbus travel at least 100 m (328 ft) from their nests, and impacts within this area could impact the nests of these pollinators (Greenleaf et al. 2007, pp. 589-596). In the case of the A. microcymbus site with cheatgrass, we estimate that the cheatgrass invasion was facilitated by the road and has since moved roughly 20 m (66 ft) upslope into the site (USFWS 2010, pers. comm.). A 100-m (328-ft) buffer (that would better account for indirect dust and invasive nonnative species effects) on either side of these roads and trails would cover roughly 46 percent of the A. microcymbus units.

Table 4—Direct and Indirect (20 Meter (66 Foot)) Effects to Astragalus microcymbus Units From Roads, Trails, and Paths Unit name Road km (mi) Trail and path km (mi) Direct Area ha (ac) % of unit 20-m (66-ft) buffer Area ha (ac) % of unit Henry 0.2 (0.1) 0.1 (0.06) 0.1 (0.2) 1.9 1.8 (4.6) 42.0 Gold Basin Creek 2.3 (1.4) 3.1 (1.9) 1.2 (3.0) 1.0 22.7 (56.0) 17.8 South Beaver Creek 1 7.5 (4.7) 8.5 (5.3) 3.8 (9.4) 1.0 69.7 (172.1) 18.7 South Beaver Creek 2 2.4 (1.5) 3.9 (2.4) 1.3 (3.2) 0.5 26.9 (66.3) 9.7 South Beaver Creek 3 0.7 (0.4) 0.3 (0.7) 0.4 3.2 (7.9) 4.8 South Beaver Creek 4 South Beaver Creek 5 0.2 (0.1) 0.01 (0.02) 0.05 0.9 (2.2)

0.2 (0.1) 0.1 (0.06) 0.1 (0.2) 1.9 1.8 (4.6) 42.0 Gold Basin Creek 2.3 (1.4) 3.1 (1.9) 1.2 (3.0) 1.0 22.7 (56.0) 17.8 South Beaver Creek 1 7.5 (4.7) 8.5 (5.3) 3.8 (9.4) 1.0 69.7 (172.1) 18.7 South Beaver Creek 2 2.4 (1.5) 3.9 (2.4) 1.3 (3.2) 0.5 26.9 (66.3) 9.7 South Beaver Creek 3 0.7 (0.4) 0.3 (0.7) 0.4 3.2 (7.9) 4.8 South Beaver Creek 4 South Beaver Creek 5 0.2 (0.1) 0.01 (0.02) 0.05 0.9 (2.2) 5.8 South Beaver Creek 6 0.2 (0.1) 0.01 (0.02) 0.2 0.9 (2.2) 19.4 Cebolla Creek 0.6 (0.4) 0.3 (0.7) 2.8 2.7 (6.8) 27.7 Total (km) 13.7 (8.5) 16.0 (9.9) 6.9 (17.1) 0.8 128.7 (318.1) 14.5 Given the numerous roads and trails within Astragalus microcymbus' habitat (impacting between 15 and 46 percent of the units), the dispersed and bisecting nature of these roads and trails, the numerous trespass trails, the likely increase in nonnative invasive plants from road and trail use, and the fact that a recreation area was designated on 40 percent of the species habitat, we find the magnitude of the threat from recreation, roads, and trails to be high. The threat is ongoing with a high likelihood that it will continue to increase over time. Given that off-road vehicle use in Colorado is increasing 16 percent annually, that the population of Gunnison County is estimated to double by 2050, and that other recreational impacts also are increasing at a rapid pace, we expect a significant increase in the threat from recreation, roads, and trails in the next 40 years. The Hartman Rocks Recreation Area's Management Plan is applicable for 10-15 years from 1995, although there is no definitive expiration date (BLM 2005a, p. 7). We are unsure if and when an update is planned. The most recent Travel Management Plan (USFS and BLM 2010, entire) for the Gunnison Basin will have a similar lifespan. During this time period travel management is not likely to change while we anticipate use will increase

ea's Management Plan is applicable for 10-15 years from 1995, although there is no definitive expiration date (BLM 2005a, p. 7). We are unsure if and when an update is planned. The most recent Travel Management Plan (USFS and BLM 2010, entire) for the Gunnison Basin will have a similar lifespan. During this time period travel management is not likely to change while we anticipate use will increase. Based on the above information, we consider recreation, roads, and trails to be a significant threat to the species now and in the foreseeable future.

Utility Corridors

Utility corridors have similar effects to habitats as roads because both are linear disturbances ( see Recreation, Roads, and Trails above for a review of effects). The impact from a utility corridor is greater than its actual footprint, because utility corridors fragment habitat and facilitate the invasion of nonnative invasive plants. We are aware of one large electrical transmission line in Astragalus microcymbus habitat. The Curecanti to Poncha 230-kilovolt electrical transmission line bisects the South Beaver Creek 1 Unit and was built in 1962 (Japuntich 2010e, pers. comm.). A 500-foot right-of-way (ROW) (largely not disturbed) is on both sides of the power line (Japuntich 2010e, pers. comm.), which overlays with about 38 ha (94 ac) or 10 percent of the South Beaver Creek 1 Unit and 4 percent of the total area of all A. microcymbus units. Only a small proportion of the 500-foot ROW is disturbed. We estimate 1.2 km (0.75 mi) of transmission line with at least six large structures (power poles) within the unit. Given the close proximity of A. microcymbus individuals to the transmission line, we assume some individuals were impacted during construction. At least one access road to a power pole also provides vehicular access to an A. microcymbus site where plants are being impacted by vehicles driving on them. This transmission line is used recreationally by snowmobile riders in the winter (BLM 2005a, p. 53)

ven the close proximity of A. microcymbus individuals to the transmission line, we assume some individuals were impacted during construction. At least one access road to a power pole also provides vehicular access to an A. microcymbus site where plants are being impacted by vehicles driving on them. This transmission line is used recreationally by snowmobile riders in the winter (BLM 2005a, p. 53). We do not know if there are any impacts to A. microcymbus from these snowmobiling activities. Direct impacts seem unlikely from the snowmobiling because the plants are dormant and under snow when the use is occurring. Compaction to the habitat is a possibility.

Future ROW developments are allowed in the South Beaver Creek ACEC provided that the surface disturbance does not impair or degrade Astragalus microcymbus sites (BLM 1993, p. 2.30). The one known utility corridor impacts only one A. microcymbus unit, representing 4 percent of the total rangewide area within units. Given the population growth in the area, we believe there is a moderate likelihood of additional utility corridors in the future. We are unaware of any plan to develop other utility corridors through A. microcymbus habitat. Although an existing utility corridor in A. microcymbus habitat may impact a small percentage of the overall range of the species, we have no information to indicate that utility corridors occur at a level that threatens the species now or in the foreseeable future.

Nonnative Invasive Plants

Nonnative invasive plants (weeds) invade and alter all types of plant communities, sometimes resulting in nonnative plant monocultures that support little wildlife or native plants. Many experts believe that, following habitat destruction, nonnative invasive plants are the next greatest threat to biodiversity (Randall 1996, pp. 370-383). Nonnative invasive plants alter different ecosystem attributes including geomorphology, fire regime, hydrology, microclimate, nutrient cycling, and productivity (Dukes and Mooney 2004, pp. 411-437)

at support little wildlife or native plants. Many experts believe that, following habitat destruction, nonnative invasive plants are the next greatest threat to biodiversity (Randall 1996, pp. 370-383). Nonnative invasive plants alter different ecosystem attributes including geomorphology, fire regime, hydrology, microclimate, nutrient cycling, and productivity (Dukes and Mooney 2004, pp. 411-437). Nonnative invasive plants can detrimentally affect native plants through competitive exclusion, altered pollinator behaviors, niche displacement, hybridization, and changes in insect predation. Invasive grasses can replace native plants such as Astragalus microcymbus by outcompeting them for resources, such as soil nutrients or moisture (Brooks and Pyke 2001, p. 6). Examples are widespread among taxa and locations or ecosystems (D'Antonio and Vitousek 1992, pp. 63-87; Olson 1999, pp. 6-18; Mooney and Cleland 2001, pp. 5446-5451).

The only nonnative invasive plant species that has been documented impacting Astragalus microcymbus is cheatgrass or downy brome ( Bromus tectorum ). Cheatgrass has become dominant in many sagebrush areas during the last century, primarily from livestock use, agriculture, and wildfire impacts (Pickford 1932, p. 165; Piemeisel 1951, p. 71; Peters and Bunting 1994, p. 34; Vail 1994, pp. 3-4; Brooks and Pyke 2001, pp. 4-6; Menakis et al. 2003, p. 284). Cheatgrass displaces native plants by prolific seed production, early germination, and superior competitive abilities for the extraction of water and nutrients (Pellant 1996, pp. 3-4; Pyke 2007, pp. 1-2). Cheatgrass is capable of modifying ecosystems by altering the soil temperatures and soil water distribution (Pellant 1996, p. 4). In addition, the invasion of cheatgrass increases fire frequency within the sagebrush ecosystem (see Wildfire below) (Zouhar et al. 2008, p. 41; Miller et al. in press, p. 39)

ilities for the extraction of water and nutrients (Pellant 1996, pp. 3-4; Pyke 2007, pp. 1-2). Cheatgrass is capable of modifying ecosystems by altering the soil temperatures and soil water distribution (Pellant 1996, p. 4). In addition, the invasion of cheatgrass increases fire frequency within the sagebrush ecosystem (see Wildfire below) (Zouhar et al. 2008, p. 41; Miller et al. in press, p. 39).

In the mid to late 1980s, cheatgrass was seen in very small patches in the Gunnison Basin but can now be found in some abundance throughout the Basin (BLM 2009a, pp. 7-8). Cheatgrass is increasing in the South Beaver Creek drainage and has been identified as a major threat to Astragalus microcymbus. This threat assessment was made because of how cheatgrass is rapidly expanding elsewhere in the Gunnison Basin (BLM 2010, p. 5). Cheatgrass is moving upslope into A. microcymbus areas (BLM 2010, p. 5). In 2009, nine polygons within the South Beaver Creek 1 Unit were discovered with cheatgrass totaling 0.2 ha (0.6 ac) (USFWS 2010b, pp. 16-17). These polygons did not exist 4 years prior to their discovery (Japuntich 2010f, pers. comm.). In 2010, another small site of cheatgrass was mapped immediately adjacent to the South Beaver Creek 5 Unit, and a 9-ha (22-ac) site with cheatgrass was located 250 m (820 ft) away from the South Beaver Creek 4 Unit (Japuntich 2010f, pers. comm.).

Herbicide use to control cheatgrass in the South Beaver Creek is limited by the close proximity of South Beaver Creek, because chemical spraying within the South Beaver Creek ACEC is not allowed, and vegetative treatments in the South Beaver Creek ACEC must not adversely affect Astragalus microcymbus (BLM 1993, p. 2.29; BLM 2010, p. 6). In the spring of 2010, the BLM conducted a mechanical removal A. microcymbus at the South Beaver Creek 1 Unit at the nine polygons mentioned above (BLM 2010, pers. comm.). A manual hand-pulling effort in 2010 that treated several acres of cheatgrass was partially successful (Japuntich 2010g, pers. comm.)

eek ACEC must not adversely affect Astragalus microcymbus (BLM 1993, p. 2.29; BLM 2010, p. 6). In the spring of 2010, the BLM conducted a mechanical removal A. microcymbus at the South Beaver Creek 1 Unit at the nine polygons mentioned above (BLM 2010, pers. comm.). A manual hand-pulling effort in 2010 that treated several acres of cheatgrass was partially successful (Japuntich 2010g, pers. comm.). Cheatgrass spread also may be affected by climate change (see Climate Change below).

Other nonnative invasive species known from the Hartman Rocks Recreation Area include: Canada thistle ( Cirsium arvense ), scentless chamomile ( Matriacaria perforata ), yellow toadflax ( Linaria vulgaris ), and Russian knapweed ( Acroptilon repens ) (BLM 2005a, p. 47). These species have not been reported from or near Astragalus microcymbus areas and are said to have been controlled (BLM 2005a, p. 47). We expect other nonnative invasive species are likely in the area. Other nonnative invasive species known from the Gunnison Resource Area that are reported to take over large areas include: spotted knapweed ( Centaurea maculosa ), oxeye daisy ( Leucanthemum vulgare), and field bindweed ( Convolvulus arvensis) (BLM 2009a, p. 7). The following weeds also are known from the Gunnison Basin, where they are currently limited in extent; however, they are known to cover large expanses in other parts of western North America: diffuse knapweed ( Centaurea diffusa ), and whitetop ( Cardaria draba ). Other invasive plant species present within the Gunnison Basin that are problematic yet less likely to overtake large areas include: musk thistle ( Carduus nutans ), bull thistle ( Cirsium vulgare ), black henbane ( Hyoscyamus niger), kochia ( Kochia sp.), common tansy (Tanacetum vulgare ), and absinth wormwood ( Artemisia biennis ) (BLM 2009a, p. 7; Gunnison Watershed Weed Commission (GWWC) 2009, pp. 4-6) .

We believe the invasion of nonnative invasive plants, particularly cheatgrass, is likely to be a threat to A

s include: musk thistle ( Carduus nutans ), bull thistle ( Cirsium vulgare ), black henbane ( Hyoscyamus niger), kochia ( Kochia sp.), common tansy (Tanacetum vulgare ), and absinth wormwood ( Artemisia biennis ) (BLM 2009a, p. 7; Gunnison Watershed Weed Commission (GWWC) 2009, pp. 4-6) .

We believe the invasion of nonnative invasive plants, particularly cheatgrass, is likely to be a threat to A. microcymbus in the near future because: (1) Cheatgrass appears to be quickly expanding into the habitat (it was unknown just 2 years ago and there are several cheatgrass sites nearby now); (2) the dry, sparsely-vegetated, south-facing slopes where A. microcymbus is found are the warmest sites with little competition from other native vegetation (Japuntich 2010h, pers. comm.) and, therefore, are inherently vulnerable to cheatgrass invasion; (3) cheatgrass likely competes with seedlings and resprouting adult plants for water and nutrients; (4) no landscape-scale successful control methods are available for cheatgrass; and (5) the proven ability of cheatgrass to increase fire frequency, thereby facilitating further rapid spread. We conclude that cheatgrass invasion is currently not a threat but we expect that the existing invasion will increase quickly in the near future, and will likely cause fire frequency to increase.

Wildfire

To date, we are aware of only one recent wildfire near Astragalus microcymbus habitat (BLM2009a, p. 6). The wildfire burned in 2007 and was 8.1 ha (20 ac) (BLM 2009a, p. 6) in size. The fire burned at a distance of 2-2.5 km (1.25-1.5 mi) away from two A. microcymbus units-Henry and Gold Basin Creek. This wildfire was just outside the northwest edge of the Hartman Rocks Recreation Area, adjacent to private land. Three wildfires have burned within the sagebrush of the Gunnison Basin in the last 15 years, the biggest was 200 ha (500 ac) (Japuntich 2010h, pers. comm.). To date there has not been a demonstrated change in the fire cycle where A. microcymbus is found, and fire frequency is low

reek. This wildfire was just outside the northwest edge of the Hartman Rocks Recreation Area, adjacent to private land. Three wildfires have burned within the sagebrush of the Gunnison Basin in the last 15 years, the biggest was 200 ha (500 ac) (Japuntich 2010h, pers. comm.). To date there has not been a demonstrated change in the fire cycle where A. microcymbus is found, and fire frequency is low.

A common result of the invasion of cheatgrass is an increase in fire frequency within the sagebrush ecosystem (Whisenant 1990, pp. 4-10; D'Antonio and Vitousek 1992, pp. 63-87; Hilty et al. 2004, pp. 89-96; Zouhar et al. 2008, p. 41; Miller et al. in press, p. 39). Cheatgrass changes historical fire patterns by providing an abundant and easily ignitable fuel source that facilitates fire spread. While sagebrush is killed by fire and is slow to reestablish, cheatgrass recovers within 1-2 years of a fire event (Young and Evans 1978, p. 285). This annual recovery ultimately leads to a reoccurring fire cycle that prevents sagebrush reestablishment (Eiswerth et al. 2009, p. 1324). The highly invasive nature of cheatgrass poses increased risk of fire and permanent loss of sagebrush habitat, as areas disturbed by fire are highly susceptible to further invasion and ultimately habitat conversion to an altered community state. For example, Link et al. (2006, p. 116) show that risk of fire increases from approximately 46-100 percent when ground cover of cheatgrass increases from 12-45 percent or more. While cheatgrass cover is still very low within Astragalus microcymbus habitat, within the Intermountain West, invasion has occurred rapidly, especially after wildfire.

Organisms adapt to disturbances such as historical wildfire regimes (fire frequency, intensity, and seasonality) with which they have evolved (Landres et al. 1999, p. 1180), and different species respond differently to wildfire (Hessl and Spackman 1995, pp. 1-90)

ry low within Astragalus microcymbus habitat, within the Intermountain West, invasion has occurred rapidly, especially after wildfire.

Organisms adapt to disturbances such as historical wildfire regimes (fire frequency, intensity, and seasonality) with which they have evolved (Landres et al. 1999, p. 1180), and different species respond differently to wildfire (Hessl and Spackman 1995, pp. 1-90). We do not know what Astragalus microcymbus' response to wildfire is at this time because none of the species' habitat has burned. Other Astragalus species have demonstrated varying responses to wildfire (see A. schmolliae below; and A. anserinus in 74 FR 46526-46529, September 10, 2009). If fire frequency increases in the area, we expect it would have deleterious effects to the habitat, given that big sagebrush recovers slowly, which would presumably affect the ecosystem, and cheatgrass tends to thrive after a wildfire.

We have no information to indicate that wildfires currently occur at levels that impact the species. No fires have burned Astragalus microcymbus habitat. However, wildfires have occurred in the area. Furthermore, we realize there is a strong relationship between cheatgrass invasions and fire frequency. If cheatgrass invasion continues to expand as discussed above, the threat of wildfire is likely to increase in the future. Given the small population size of A. microcymbus and the potential damage a wildfire could cause, we consider future wildfires to be a threat to the species.

Contour Plowing and Nonnative Seedings

Areas within the Hartman Rocks Recreation Areas (but largely outside of the Astragalus microcymbus units) have been subject to contour plowing and the subsequent seeding of nonnative species, as well as the development of silt and water impoundment structures (BLM 2005a, p. 57), which can destroy A. microcymbus habitat. Contour plowing is the past practice of plowing across a slope following elevation lines and is commonly done to prevent soil erosion

rgely outside of the Astragalus microcymbus units) have been subject to contour plowing and the subsequent seeding of nonnative species, as well as the development of silt and water impoundment structures (BLM 2005a, p. 57), which can destroy A. microcymbus habitat. Contour plowing is the past practice of plowing across a slope following elevation lines and is commonly done to prevent soil erosion. We are unsure why contour plowing and seeding efforts were undertaken near A. microcymbus habitat but expect that erosion control and improving livestock forage may have been the primary reasons for these efforts. We have no site-specific data regarding these activities, nor do we know when they occurred. We expect the contour plowing was done to improve range conditions by eliminating sagebrush and increasing grazing and drought-tolerant grasses for forage by livestock. The contour lines from these efforts can be seen through satellite imagery and occur largely on BLM-managed lands. Within the Hartman Rocks Recreation Area, we estimate that roughly 18 percent (617 ha (1,524 ac)) have been contour plowed. Only 1.2 percent (11 ha (27 ac)) of the A. microcymbus units have been A. microcymbus in the past. We speculate there may have been an impact to the species from these seeding efforts in the past given that there is very little overlap between the Gold Basin Creek Unit and the contoured areas, despite the contoured areas surrounding the unit on the east, north and west sides (USFWS 2010b, p. 19).

These contoured areas were seeded with crested wheatgrass ( Agropyron cristatum ). Most areas where Astragalus microcymbus is found do not overlap with sites where crested wheatgrass is found in abundance (USFWS 2010b, pp. 18-19). Crested wheatgrass is commonly found outside the contoured areas at the Gold Basin Creek and Henry Units (USFWS 2010, pers. comm.), and we assume it has spread into these adjacent native habitats from the contoured areas

tgrass ( Agropyron cristatum ). Most areas where Astragalus microcymbus is found do not overlap with sites where crested wheatgrass is found in abundance (USFWS 2010b, pp. 18-19). Crested wheatgrass is commonly found outside the contoured areas at the Gold Basin Creek and Henry Units (USFWS 2010, pers. comm.), and we assume it has spread into these adjacent native habitats from the contoured areas. Crested wheatgrass is often used for rangeland seedings because seed is widely available, it establishes easily, provides suitable forage for livestock, provides some erosion control, and controls competition from other nonnative invasive plants (Walker and Shaw 2005, p. 56). Crested wheatgrass is extremely competitive and can out-compete other vegetation in several ways (Pellant and Lysne 2005, pp. 82-83). Grasses, such as crested wheatgrass, are wind pollinated and, therefore, do not provide resources such as nectar or edible pollen for pollinators.

The contour plowings and seedings of crested wheatgrass affect only a small proportion (1.2 percent) of the Astragalus microcymbus units. The likelihood of future seedings is low because vegetative treatments that would adversely affect A. microcymbus are no longer allowed (BLM 1993, p. 2.29). Because crested wheatgrass continues to invade native habitats from these seedings, and because the plowed areas may not provide good floral resources for pollinators, we find these continuing effects of past contour plowing and nonnative seeding to impact the species but not to the point where it poses a threat to the continued existence of the species. We expect crested wheatgrass and pollinator impacts to continue into the foreseeable future since it does not appear that the crested wheatgrass is disappearing.

Livestock, Deer, and Elk Use of Habitat

Livestock Use—Potential threats related to livestock, deer, and elk use include the eating of individual plants (included in Factor C below), physical effects from the trampling, and the indirect effects of habitat degradation

pollinator impacts to continue into the foreseeable future since it does not appear that the crested wheatgrass is disappearing.

Livestock, Deer, and Elk Use of Habitat

Livestock Use—Potential threats related to livestock, deer, and elk use include the eating of individual plants (included in Factor C below), physical effects from the trampling, and the indirect effects of habitat degradation. We are unaware of any research or monitoring that has evaluated the effects of livestock, deer, or elk use on Astragalus microcymbus. However, the deleterious effects of livestock on western arid ecosystems are well documented (Milchunas et al. 1992, pp. 520-531; Jones 2000, pp. 155-164). Some of the adverse effects from livestock include changes in the timing and availability of pollinator food plants (Kearns and Inouye 1997, pp. 298-299); changes to insect communities (Kearns and Inouye 1997, pp. 298-299; Debano 2006, pp. 2547-2564); damage to ground-nesting pollinators and their nests (Sugden 1985, p. 309); changes in water infiltration due to soil compaction (Jones 2000, Table 1); disturbance to soil microbiotic crusts (Belnap et al. 1999, p. 167; Jones 2000, Table 1); subsequent nonnative invasive plant invasions (Parker et al. 2006, pp. 1459-1461); and soil erosion from hoof action (Jones 2000, Table 1).

Without any species-specific research or monitoring of livestock use, our understanding of impacts to Astragalus microcymbus is limited and observational in nature. Little livestock grazing has been recorded within A. microcymbus areas; most plants are located on steep slopes with little vegetation that do not draw cows to them (BLM 2010, p. 4). We expect that the plant was always found primarily on slopes, but do not know if the current distribution has been influenced by increased livestock use in flatter areas. In 2008, after visiting all A. microcymbus sites, only one appeared to have been directly grazed by livestock (BLM 2010, p. 5). Several observers have attributed increased erosion within A

not draw cows to them (BLM 2010, p. 4). We expect that the plant was always found primarily on slopes, but do not know if the current distribution has been influenced by increased livestock use in flatter areas. In 2008, after visiting all A. microcymbus sites, only one appeared to have been directly grazed by livestock (BLM 2010, p. 5). Several observers have attributed increased erosion within A. microcymbus sites to cattle use, but this impact also could be from deer or elk use (CNHP 2010a, pp. 12, 27, 32). Grazing utilization levels were reportedly low in 1994 but physical damage to A. microcymbus individuals from trampling at two sites was noted (Sherwood 1994, pp. 11, 17, 20). In another review, the authors speculated the periodicity and intensity of grazing may influence the success of A. microcymbus by the removal of individuals and ground cover, thereby influencing seedling success (Peterson et al. 1981, p. 16). Numerous livestock trails, feces, and tracks were found within most A. microcymbus sites visited in 2010 (USFWS 2010, pers. comm.). Within the Hartman Rocks Recreation Area, overall plant cover has been reduced by historic excessive livestock grazing, drought, grazing during the extreme drought years of 1990 through 1992, 2000, and 2001, and the physical impacts from roads and trails (BLM 2005a, p. 56).

Although grazing damage is minimal, all Astragalus microcymbus areas receive at least some livestock use. Aside from the Cebolla Creek Unit, all units on BLM lands are either in the Gold Basin or Iola grazing allotments and are actively grazed by cattle. Those units with private lands also are grazed on their private portions. In total, 56.1 percent of the A. microcymbus units fall within the Gold Basin allotment and 43.9 percent fall within the Iola allotment, with no ungrazed areas (BLM 2010; USFWS 2010b, pp. 6-7)

Cebolla Creek Unit, all units on BLM lands are either in the Gold Basin or Iola grazing allotments and are actively grazed by cattle. Those units with private lands also are grazed on their private portions. In total, 56.1 percent of the A. microcymbus units fall within the Gold Basin allotment and 43.9 percent fall within the Iola allotment, with no ungrazed areas (BLM 2010; USFWS 2010b, pp. 6-7). Within the South Beaver Creek ACEC, no additional forage allocations, beyond those already authorized for the allotments will be made and domestic sheep grazing will not be authorized (BLM 2005a, pp. 2-29 to 2-30).

Fences and water developments have been constructed within the range of Astragalus microcymbus to help manage livestock grazing activities, increase the number of livestock that the landscape can support, keep animals in specific areas, and distribute grazing more evenly on the landscape (BLM 2005a, p. 12). All of the pastures are fenced, so the four A. microcymbus units with multiple pastures or allotments also have fences (Gold Basin Creek, South Beaver Creek 1, South Beaver Creek 2, and South Beaver Creek 3).

Water developments occur across the range of Astragalus microcymbus (Japuntich 2010i, pers. comm.). One water development is within 300 m (985 ft) of the Henry Unit: one is within and three are just outside the Gold Basin Creek Unit; and an additional three developments are just outside the unit: one within the South Beaver Creek 1 Unit; and one within 400 m (1,312 ft) of the South Beaver Creek 6 Unit (Japuntich 2010i, pers. comm.). Within the Henry Unit, several livestock trails run through the A. microcymbus site. We assume these trails are from livestock travelling to and from the water development 300 m (985 ft) away and expect that similar effects are occurring from the other water developments listed above

aver Creek 1 Unit; and one within 400 m (1,312 ft) of the South Beaver Creek 6 Unit (Japuntich 2010i, pers. comm.). Within the Henry Unit, several livestock trails run through the A. microcymbus site. We assume these trails are from livestock travelling to and from the water development 300 m (985 ft) away and expect that similar effects are occurring from the other water developments listed above. Water developments concentrate livestock use in areas near these developments, and fence lines often funnel livestock, and even deer and elk, into certain areas that will receive a disproportionate amount of use. We do not have further information regarding whether the close proximity of water developments or fence lines is causing increased impacts A. microcymbus habitat, but we expect this is the case because there are several fences running through sites and because livestock grazing is found atop all sites.

In addition, salt blocks draw livestock (and deer and elk) to the areas where they are placed. We know of one instance where a salt block has been placed within an Astragalus microcymbus site. This area was extensively trampled, there were fewer A. microcymbus individuals in trampled areas than surrounding polygons, and those plants that remained were located almost exclusively under shrubs (USFWS 2010, pers. comm.). Trails to and from the salt block were impacting adjacent A. microcymbus polygons (USFWS 2010, pers. comm.). We do not know of any protective mechanisms to prevent salt block placement within A. microcymbus sites and expect this may be occurring elsewhere.

The Gold Basin allotment is authorized for use between May 16 and September 30 each year, but is used from May 25-July 31, the time when Astragalus microcymbus is growing and reproducing, in most years (BLM 2010, p. 5). Pastures used by cow/calf pairs are generally used for 5-15 days a year and those used by yearlings are generally used for 15-30 days each year

t this may be occurring elsewhere.

The Gold Basin allotment is authorized for use between May 16 and September 30 each year, but is used from May 25-July 31, the time when Astragalus microcymbus is growing and reproducing, in most years (BLM 2010, p. 5). Pastures used by cow/calf pairs are generally used for 5-15 days a year and those used by yearlings are generally used for 15-30 days each year. Pastures are rested occasionally some years, although when and how often this occurs is unknown. The Gold Basin allotment is permitted for 4,253 animal unit months (AUMs) a year but has averaged 1,405 AUMs over the last 6 years. Approximately 30 percent of the AUMs are within the pastures where A. microcymbus units are located (BLM 2010, p. 5). In 2007, this allotment was found to have heavy use in some riparian areas and poor herbaceous cover in the lowest elevation uplands, where A. microcymbus would be found. These results were attributed to historic vegetation manipulation and livestock grazing practices (BLM 2009b, pp. 1-2). Given that damage is occurring at lower than permitted stocking rates and shorter than permitted periods of time, the potential for further damage exists.

The Iola allotment is authorized for use between May 15 and November 14 each year, but is used from late May/early June (sometimes late June/early July) generally 15-20 days in most years (BLM 2009b, pp. 1-2; BLM 2010, p. 5). These times again coincide with the time when Astragalus microcymbus is growing and reproducing. The permittee is authorized up to 1,258 AUMs in the pasture, but has used an average of 250 AUMs for the last 6 years (BLM 2010, p. 5). A new allotment management plan and grazing system was developed for this allotment in 2002. During this analysis, grass cover was below potential, and riparian vegetation was being consistently grazed to less than 10 cm (4 in.) (BLM 2009b, pp. 1-2)

d reproducing. The permittee is authorized up to 1,258 AUMs in the pasture, but has used an average of 250 AUMs for the last 6 years (BLM 2010, p. 5). A new allotment management plan and grazing system was developed for this allotment in 2002. During this analysis, grass cover was below potential, and riparian vegetation was being consistently grazed to less than 10 cm (4 in.) (BLM 2009b, pp. 1-2). Again, given that damage is occurring at lower than permitted stocking rates and shorter than permitted periods of time, the potential for further damage exists.

Deer and Elk Use—Livestock impacts to the habitat are similar to those impacts to the habitat caused by excessive deer and elk use (Japuntich et al. in press, pp. 1-15). For example, Hobbs et al. (1996, pp. 200-217) documented a decline in available perennial grasses as elk densities increased. All Astragalus microcymbus areas are within areas that receive deer and elk use. Grazing and browsing by deer and elk occurs primarily during the winter months when there is less snow in the valley than the surrounding hills. Deer numbers have seen a strong increase in the Gunnison Basin since 1999 (Gunnison-Crested Butte 2010, p. 2). A. microcymbus is found within the Powderhorn Creek Game Management Unit (deer). In 2005, this unit had between 600 and 1,600 more deer than its objective of 4,500-5,500 individuals (Colorado Division of Wildlife (CDOW) 2006, p. 3). Since 1980, deer numbers within this unit have been as high as 8,000 individuals in 1993 and as low as 4,500 individuals in 1984; and averaging near 7,000 individuals from 2000 to 2005 (CDOW 2006, p. 3). From 1980 to 2000, elk numbers in the Lake Fork Managment Unit (where A. microcymbus is found) rose from 5,600 individuals to 9,256 individuals; both numbers are substantially greater than the 3,000-3,500 population objective (CDOW 2001, pp. 3, appendix A). Currently in the Gunnison Basin, deer and elk populations have 8,000 more individuals than the desired population objectives (Japuntich et al

From 1980 to 2000, elk numbers in the Lake Fork Managment Unit (where A. microcymbus is found) rose from 5,600 individuals to 9,256 individuals; both numbers are substantially greater than the 3,000-3,500 population objective (CDOW 2001, pp. 3, appendix A). Currently in the Gunnison Basin, deer and elk populations have 8,000 more individuals than the desired population objectives (Japuntich et al. in press, p. 4).

Excessive but localized deer and elk grazing has been documented in the Gunnison Basin (BLM 2005b, pp. 17-18). For example, drought and big game were having large impacts on the survivability and size of high-protein shrubs including mountain mahogany ( Cercocarpus utahensis ), bitterbrush ( Pushia tridentata ), and serviceberry ( Amelanchier alnifolia ) in the Gunnison Basin (Japuntich et al. in press, pp. 7-9). These shrub species are not the most common within A. microcymbus habitat but are generally found nearby. These authors raised concerns that observed reductions in shrub size and vigor will reduce drifting snow accumulation resulting in decreased moisture availability to grasses and forbs during the spring melt, affecting the overall composition of the plant community.

Impacts to Astragalus microcymbus habitat from deer and elk are occurring. For example, extensive moderate to severe hedging of shrubs, attributed to fairly heavy concentrations of wintering big game animals, has been documented at one A. microcymbus site in the South Beaver Creek 5 Unit (Sherwood 1994, p. 16). Deer and elk feces can be found at most A. microcymbus sites (USFWS 2010, pers. comm.). Deer and elk use occurs primarily in the winter when A. microcymbus is dormant, which minimizes some of the direct effects to the plants. However, deer and elk are more likely to spend time on steeper slopes than livestock and so may cause more direct trampling impacts to A. microcymbus habitat including soils, seed banks, and plant communities

most A. microcymbus sites (USFWS 2010, pers. comm.). Deer and elk use occurs primarily in the winter when A. microcymbus is dormant, which minimizes some of the direct effects to the plants. However, deer and elk are more likely to spend time on steeper slopes than livestock and so may cause more direct trampling impacts to A. microcymbus habitat including soils, seed banks, and plant communities.

Summary of Livestock, Deer, and Elk Use—Describing livestock, deer, and elk use is complicated because the management of these animals is complicated. Although we lack good monitoring data, we find livestock, deer, and elk use of Astragalus microcymbus habitat to be a threat to the species. We have made this determination based upon observations that suggest moderate use levels from livestock and heavy deer and elk use in the winter. Use from livestock, deer, and elk is virtually ubiquitous across the range of the species, and habitat degradation is occurring, although we recognize that these indirect effects to A. microcymbus habitat are difficult to quantify. Authorized AUMs are significantly greater than those currently utilized. If livestock use were to increase, this threat would increase in the foreseeable future. The current number of deer and elk is above population objectives, and past fluctuations suggest that more animals are a possibility, which would also increase this threat in the foreseeable future. In addition, the accompanying habitat degradation with livestock, deer, and elk use makes this an increasing threat especially in light of the cheatgrass invasion.

Mining; Oil and Gas Leasing

The South Beaver Creek ACEC has one active lode claim and one active placer claim for mining. Lode claims are those which generally follow some deposited vein while placer mining is everything else and can include sand and gravel deposits. One of these active claims is within the Gold Basin Creek Unit, and the other is nearby

lly in light of the cheatgrass invasion.

Mining; Oil and Gas Leasing

The South Beaver Creek ACEC has one active lode claim and one active placer claim for mining. Lode claims are those which generally follow some deposited vein while placer mining is everything else and can include sand and gravel deposits. One of these active claims is within the Gold Basin Creek Unit, and the other is nearby. Neither of these claims have Notices of Intent or Plans of Operation that are required for most disturbances (BLM 2010, pp. 5-6). A. microcymbus from this gravel operation. A gravel pit was said to be on private lands at the Beaver Creek Southeast Unit, but we have no further information and, based on our maps, do not make a similar conclusion (Sherwood 1994, p. 15).

No lands for oil and gas development have been leased by the BLM within the Gunnison Basin area (USFS and BLM 2010, pp. 272-273). All habitats where Astragalus microcymbus is currently found are mapped as having no potential for oil and gas development (Gunnison Sage-Grouse Resource Steering Committee 2005, p. 130). Despite this lack of potential, the entire Federal oil, gas, and geothermal estates in the South Beaver Creek ACEC are open to leasing but with a controlled surface use stipulation (BLM 1993, pp. 2.29, K.5). This stipulation requires that inventories be conducted prior to the approval of operations and relocations of operations. These inventories will be used to prepare mitigative measures to reduce the impacts of surface disturbance to the species (BLM 1993, p. K.5).

Given that there are only two existing active mining claims (but without current activity) within Astragalus microcymbus units and that there is no potential for oil and gas development in the area, we do not consider mining or oil and gas leases to threaten the species at this time nor do we expect these factors to pose a threat to the species in the foreseeable future

ecies (BLM 1993, p. K.5).

Given that there are only two existing active mining claims (but without current activity) within Astragalus microcymbus units and that there is no potential for oil and gas development in the area, we do not consider mining or oil and gas leases to threaten the species at this time nor do we expect these factors to pose a threat to the species in the foreseeable future.

Climate Change

According to the Intergovernmental Panel on Climate Change (IPCC), “Warming of the climate system in recent decades is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global sea level” (IPCC 2007, p. 1). Average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than during any other 50-year period in the last 500 years and likely the highest in at least the past 1,300 years (IPCC 2007, p. 30). Over the past 50 years, cold days, cold nights, and frosts have become less frequent over most land areas, and hot days and hot nights have become more frequent. Heat waves have become more frequent over most land areas, and the frequency of heavy precipitation events has increased over most areas (IPCC 2007, p. 30). For the southwestern region of the United States, including western Colorado, warming is occurring more rapidly than elsewhere in the country (Karl et al. 2009, p. 129). Annual average temperature in west-central Colorado increased 3.6 °C (2 °F) over the past 30 years, but high variability in annual precipitation precludes the detection of long-term trends (Ray et al. 2008, p. 5). At one weather station in Gunnison, Colorado, temperature has increased roughly 1.8 °C (1 °F) since 1900 (WRCC 2010c, pp. 1-9).

Future projections for the southwestern United States, including the Gunnison Basin, show increased probability of drought (Karl et al. 2009, pp. 129-134)

, but high variability in annual precipitation precludes the detection of long-term trends (Ray et al. 2008, p. 5). At one weather station in Gunnison, Colorado, temperature has increased roughly 1.8 °C (1 °F) since 1900 (WRCC 2010c, pp. 1-9).

Future projections for the southwestern United States, including the Gunnison Basin, show increased probability of drought (Karl et al. 2009, pp. 129-134). Additionally, the number of days over 32 °C (90 °F) could double by the end of the century (Karl et al. 2009, p. 34). Annual temperature is predicted to increase approximately 2.2 °C (4 °F) in the southwest by 2050, with summers warming more than winters (Ray et al. 2008, p. 29). Projections also show declines in snowpack across the West with the most dramatic declines at lower elevations (below 2,500 m (8,200 ft)) (Ray et al. 2008, p. 29). Overall, future projections for the Southwest predict increased temperatures, more intense and longer-lasting heat waves, an increased probability of drought that are worsened by higher temperatures, heavier downpours, increased flooding, and increased erosion (Karl et al. 2009, pp. 129-134).

Colorado's complex, mountainous topography results in a high degree of spatial variability across the State. As a result, localized climate projections are problematic for mountainous areas because current global climate models are unable to capture this variability at local or regional scales (Ray et al. 2008, pp. 7, 20). To obtain climate projections specific to the range of Astragalus microcymbus, we used a statistically downscaled model from the National Center for Atmospheric Research for a region covering western Colorado

limate projections are problematic for mountainous areas because current global climate models are unable to capture this variability at local or regional scales (Ray et al. 2008, pp. 7, 20). To obtain climate projections specific to the range of Astragalus microcymbus, we used a statistically downscaled model from the National Center for Atmospheric Research for a region covering western Colorado. The resulting projections indicate that temperature could increase an average of 2.5 °C (4.5 °F) by 2050 with the following seasonal increases: summer (July through September) 2.8 °C (5.0 °F), fall (October through December) 2.2 °C (4.0 °F), winter (January through March) 2.3 °C (4.1 °F), and spring (April through June) 2.5 °C (4.5 °F) (University Corporation of Atmospheric Research (UCAR) 2009, pp. 1-14). This increase in temperature could be problematic for A. microcymbus because the species is negatively affected by warm temperatures during May and July (DBG 2010a, p. 6).

Annual mean precipitation projections for Colorado are unclear; however, multi-model averages show a shift toward increased winter precipitation and decreased spring and summer precipitation by the end of the century (Ray et al. 2008, p. 34; Karl et al. 2009, p. 30). Similarly, the National Center for Atmospheric Research results show the highest probability of a 7.5 percent increase in average winter (January through March) precipitation, an 11.4 percent decrease in average spring (April through June) precipitation, a 2.1 percent decrease in average summer (July through September) precipitation, and a 1.3 percent increase in average fall precipitation with an overall very slight decrease in 2050 (UCAR 2009, pp. 1-14). Seasonal trends from the past 100 years at a local weather station do not yet match this scenario, and overall precipitation has declined by roughly 2 cm (0.75 in.) or 10 percent (WRCC 2010a, pp. 1-8)

percent decrease in average summer (July through September) precipitation, and a 1.3 percent increase in average fall precipitation with an overall very slight decrease in 2050 (UCAR 2009, pp. 1-14). Seasonal trends from the past 100 years at a local weather station do not yet match this scenario, and overall precipitation has declined by roughly 2 cm (0.75 in.) or 10 percent (WRCC 2010a, pp. 1-8). This actual data is in contrast to regional maps that show precipitation has increased roughly 5 percent from 1958 to 2008 within the general area where Astragalus microcymbus resides (Karl et al. 2009, p. 30). A. microcymbus responds negatively to declines in overall precipitation and periods of drought, as well as declines in spring precipitation (May and July) (DBG 2010a, p. 6). Given the observed decline in precipitation at a local weather station, predictions of increased drought, and a predicted significant decline in spring precipitation, we expect A. microcymbus will be affected negatively by climate change effects to precipitation.

Climate change is likely to alter fire frequency, community assemblages, and the ability of nonnative species to proliferate. Increasing temperature as well as changes in the timing and amount of precipitation will alter the competitive advantage among plant species (Miller et al. in press, p. 44), and may shift individual species and ecosystem distributions (Bachelet et al. 2001, p. 174). Dominant plant species such as big sagebrush have a disproportionate control over resources et al. 2009, p. 1). For sagebrush communities, spring and summer precipitation comprises the majority of the moisture available to species; thus, the interaction between reduced precipitation in the spring-summer growing season and increased summer temperatures will likely decrease growth of big sagebrush and could result in a significant long-term reduction in the distribution and composition of sagebrush communities (Miller et al. in press, pp. 41-45)

summer precipitation comprises the majority of the moisture available to species; thus, the interaction between reduced precipitation in the spring-summer growing season and increased summer temperatures will likely decrease growth of big sagebrush and could result in a significant long-term reduction in the distribution and composition of sagebrush communities (Miller et al. in press, pp. 41-45). In the Gunnison Basin, increased summer temperature was strongly correlated with reduced growth of big sagebrush (Poore et al. 2009, p. 558). Although we do not fully understand how changes in plant communities will affect Astragalus microcymbus, we expect that a decrease in the dominant plant species will not be a benefit because it could drastically alter the way the ecosystem functions where A. microcymbus resides. In addition, changes in the plant community could likely influence wildfire frequency and erosion rates.

Temperature increases may increase the competitive advantage of cheatgrass in higher elevation areas where it is currently limited (Miller et al. in press, p. 47), like the Gunnison Basin. Decreased summer precipitation, as predicted in the model, reduces the competitive advantage of summer perennial grasses, reduces sagebrush cover, and subsequently increases the likelihood of cheatgrass invasion (Prevey et al. 2009, pp. 1-13). This impact could increase the susceptibility of areas within Astragalus microcymbus' range to cheatgrass invasion (Bradley 2009, p. 204). In addition, cheatgrass and other C3 grasses (C3 refers to one of three alternative photosynthetic pathways) are likely to thrive as atmospheric carbon dioxide increases (Mayeux et al. 1994, p. 98). An increase in cheatgrass would likely increase wildfire frequency. See Nonnative Invasive Plants above for a discussion of cheatgrass and effects to A. microcymbus.

Climate change predictions are based on models with assumptions, and are not absolute

ers to one of three alternative photosynthetic pathways) are likely to thrive as atmospheric carbon dioxide increases (Mayeux et al. 1994, p. 98). An increase in cheatgrass would likely increase wildfire frequency. See Nonnative Invasive Plants above for a discussion of cheatgrass and effects to A. microcymbus.

Climate change predictions are based on models with assumptions, and are not absolute. In addition, we do not fully understand how climate change will affect the species or the habitat in which it resides. These factors make it difficult to predict the effects of climate change to Astragalus microcymbus. However, endemic species with limited ranges that are adapted to localized conditions, like A. microcymbus, are expected to be more severely impacted by climate change (Midgley et al. 2002, p. 448) than those considered habitat generalists. Furthermore, we expect the predicted increases in spring temperature, increased drought, and decreased spring precipitation will affect A. microcymbus negatively. Climate change has the potential to change the plant community, allow cheatgrass to increase, and potentially increase the risk of wildfire, which would likely have a negative effect to A. microcymbus. It is difficult to assess the threat of climate change to A. microcymbus given the uncertainties associated with future projections. However, based on the best available information on climate change projections into the next 40 years, we find climate change to be a threat to A. microcymbus based on how predicted changes could negatively influence the species. We recognize there are many uncertainties, and projections further into the future become even more uncertain, making it even more difficult to predict how climate change might affect the species.

Habitat Fragmentation and Degradation

Habitat fragmentation can have negative effects on biological populations

o A. microcymbus based on how predicted changes could negatively influence the species. We recognize there are many uncertainties, and projections further into the future become even more uncertain, making it even more difficult to predict how climate change might affect the species.

Habitat Fragmentation and Degradation

Habitat fragmentation can have negative effects on biological populations. Often fragments are not of sufficient size to support the natural diversity prevalent in an area and so exhibit a decline in biodiversity (Noss and Cooperrider 1994, pp. 50-54). Habitat fragments are often functionally smaller than they appear because edge effects (such as increased nonnative species or wind speeds) impact the available habitat within the fragment (Lienert and Fischer 2003, p. 597). Habitat fragmentation has been shown to disrupt plant-pollinator interactions and predator-prey interactions (Steffan-Dewenter and Tscharntke 1999, pp. 432-440), alter seed germination percentages (Menges 1991, pp. 158-164), and result in low fruit set (Cunningham 2000, pp. 1149-1152). Extensive habitat fragmentation can result in dramatic fluxes in available solar radiation, water, and nutrients (Saunders et al. 1991, pp. 18-32).

Fragmentation within Astragalus microcymbus habitat is largely from linear features such as roads and utility corridors (see Recreation, Roads, and Trails and Utility Corridors above) that are pervasive at every A. microcymbus unit except the South Beaver Creek 4 Unit. In addition, past contour plowings and subsequent seeding efforts have created blocks of altered and degraded habitat around A. microcymbus units that may affect the overall plant community, nonnative invasive plants, and pollinator habitat and resources. This type of fragmentation does not carry the same negative consequences as that of more highly fragmented habitats impacted by agricultural or urban development because of its more limited extent.

However, the aforementioned type of fragmentation leads to habitat degradation

ymbus units that may affect the overall plant community, nonnative invasive plants, and pollinator habitat and resources. This type of fragmentation does not carry the same negative consequences as that of more highly fragmented habitats impacted by agricultural or urban development because of its more limited extent.

However, the aforementioned type of fragmentation leads to habitat degradation. Habitat degradation, the gradual deterioration of habitat quality, can lead to a species decline, decrease, or loss of reproductive ability. Habitat degradation may be difficult to detect because it takes place over a long time period, and species with long life-cycles may continue to be present in an area even if they are unable to breed (Fisher and Lindenmayer 2007, pp. 268-269).

In the case of Astragalus microcymbus, habitat degradation is coming from multiple sources: Development; recreation, roads, and trails; utility corridors; nonnative invasive plants; contour plowing and nonnative seedings; and accentuated by periodic drought. In addition, wildfire and climate change will likely contribute to further habitat degradation. Detailed monitoring is needed to detect population changes and signal the need to implement conservation measures that could counteract habitat degradation, but this monitoring has not been done for A. microcymbus.

Habitat fragmentation and habitat degradation is occurring as a result of multiple sources including virtually all the threats and factors previously described in this document. As a result, we find habitat degradation to be a threat to Astragalus microcymbus. Habitat fragmentation is currently a lesser threat, but because it is so tightly linked with habitat degradation, we have treated them jointly

itat fragmentation and habitat degradation is occurring as a result of multiple sources including virtually all the threats and factors previously described in this document. As a result, we find habitat degradation to be a threat to Astragalus microcymbus. Habitat fragmentation is currently a lesser threat, but because it is so tightly linked with habitat degradation, we have treated them jointly.

Summary of Factor A

The biggest habitat-related threats to Astragalus microcymbus are recreation (including roads and trails); the potential for increases in nonnative invasive plants (especially cheatgrass); potential residential and urban development; livestock, deer, and elk use; and potential effects from climate change. In addition, the habitat degradation and fragmentation occurring from these stressors threatens A. microcymbus.

Recreational impacts are not likely to lessen given the close proximity of Astragalus microcymbus to the town of Gunnison and the increasing popularity of mountain biking, motorcycling, and all-terrain vehicles. The fact that the Hartman Rocks Recreation Area was designated on 40 percent of the A. microcymbus units will only serve to draw more users, and there is little enforcement to control trespass use.

Although the impacts from nonnative invasive plants, and particularly cheatgrass, are low right now, we expect this factor to increase to the level of a serious threat in the near future. Cheatgrass is increasing in the South Beaver Creek drainage and has been identified as a major threat to Astragalus microcymbus (BLM 2010, p. 5). In the mid to late 1980s, cheatgrass was seen in very small patches in the Gunnison Basin but can now be found in some abundance throughout the Basin (BLM 2009a, pp. 7-8). A. microcymbus is found on warm, sparsely vegetated, and dry, south-facing slopes, which in the Gunnison Basin, are probably more vulnerable to cheatgrass invasion. We know that cheatgrass is already invading A. microcymbus sites

n the mid to late 1980s, cheatgrass was seen in very small patches in the Gunnison Basin but can now be found in some abundance throughout the Basin (BLM 2009a, pp. 7-8). A. microcymbus is found on warm, sparsely vegetated, and dry, south-facing slopes, which in the Gunnison Basin, are probably more vulnerable to cheatgrass invasion. We know that cheatgrass is already invading A. microcymbus sites. Cheatgrass has transformed millions of acres into monocultures in the Great Basin and has dramatically shortened the wildfire return interval. We believe the potential exists for a similar conversion in A. microcymbus habitat. Although we find the current invasion of cheatgrass into A. microcymbus habitat to be small and possess little threat, because of the high potential for further invasion, we find the overall threat is increasing.

It is difficult to assess the impact of climate change to Astragalus microcymbus, but we believe climate change may be a future threat given the predictions of increased springtime temperatures, decreased springtime precipitation, and increased drought.

Because a quarter of the Astragalus microcymbus units occur on private land, and given the rapid pace of development in the Gunnison Basin, we believe residential and urban development represent a moderate threat to A. microcymbus. Given that livestock, deer, and elk use occurs across the range of A. microcymbus, that A. microcymbus individuals are being lost from this use, and that this use is causing habitat degradation that could facilitate the spread of cheatgrass, we find this threat to be moderate.

We find the potential impact of future wildfire to be a threat to the species and recognize that wildfire risk may increase with further cheatgrass invasion. We do not find utility corridors to be a threat because they currently impact only 4 percent of the A. microcymbus units and we do not know of any further utility corridor plans

the spread of cheatgrass, we find this threat to be moderate.

We find the potential impact of future wildfire to be a threat to the species and recognize that wildfire risk may increase with further cheatgrass invasion. We do not find utility corridors to be a threat because they currently impact only 4 percent of the A. microcymbus units and we do not know of any further utility corridor plans. We do not find the continuing effects from past contour plowings and nonnative seedings to be a threat because the existing plowings only impact 1.2 percent of the A. microcymbus units and we do not expect these treatments to occur in the future. Because of the low potential for oil and gas development and because there are only two other active mining claims within the species' range, we do not find that these factors are threats to the species.

Based on threats from recreation; the potential for increases in nonnative invasive plants; potential residential and urban development; livestock, deer, and elk use; and potential effects from climate change, we find that Astragalus microcymbus is threatened by the present or threatened destruction, modification, or curtailment of its habitat or range now and these threats are expected to continue or increase in the foreseeable future.

Factor B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes

We are not aware of any threats involving the overutilization or collection of Astragalus microcymbus for any commercial, recreational, scientific, or educational purposes at this time. A. microcymbus is not particularly showy or of horticultural significance; therefore, we do not expect any overutilization in the foreseeable future. We find that overutilization for commercial, recreational, scientific, or educational purposes is not a threat to A. microcymbus now or expected to become so in the foreseeable future.

Factor C

nal, scientific, or educational purposes at this time. A. microcymbus is not particularly showy or of horticultural significance; therefore, we do not expect any overutilization in the foreseeable future. We find that overutilization for commercial, recreational, scientific, or educational purposes is not a threat to A. microcymbus now or expected to become so in the foreseeable future.

Factor C. Disease or Predation

Astragalus microcymbus is subject to extensive herbivory, primarily from small mammals (Lyon 1990, pp. 2, 5; Dyer 1993, p. 2; Sherwood 1994, pp. 10-11; Japuntich 2010j, pers. comm.; DBG 2010a, pp. 6-7). On average, 26 percent of the plants have evidence of herbivory (ranging from 13 to 74 percent at a given plot) (DBG 2010a, p. 6). Browsing on the plants is very evident and in some areas, it is hard to find an A. microcymbus individual that has not had at least some portion eaten (Japuntich 2010j, pers. comm.). Some species of Astragalus are notoriously toxic to livestock, and presumably deer and elk. Often these toxic species are avoided by grazers and browsers. However, the high level of small mammal herbivory to A. microcymbus plants suggests the species is not overly toxic. We do not know if this toxicity would vary between livestock and rabbits.

Small Mammal Herbivory

Most herbivory of Astragalus microcymbus individuals is attributed to small mammals. Cottontail rabbits ( Sylvilagus audobonii ), small chipmunks ( Tamias sp.), and ground squirrels ( Citellus lateralis and others) graze on A. microcymbus (Japuntich 2010j, pers. comm.). Mice and voles also have been implicated as herbivores (Sherwood 1994, p. 11). Rabbits are generally considered the primary herbivores of A. microcymbus, and numerous observers have suggested they are in abundance within A. microcymbus habitat (Lyon 1990, p. 2; Dyer 1993, p. 2; Japuntich 2010j, pers. comm.)

ls ( Citellus lateralis and others) graze on A. microcymbus (Japuntich 2010j, pers. comm.). Mice and voles also have been implicated as herbivores (Sherwood 1994, p. 11). Rabbits are generally considered the primary herbivores of A. microcymbus, and numerous observers have suggested they are in abundance within A. microcymbus habitat (Lyon 1990, p. 2; Dyer 1993, p. 2; Japuntich 2010j, pers. comm.).

The information we have regarding rabbit herbivory is mostly anecdotal in nature; however, taken in sum, we believe this information leads to a conclusion that rabbit herbivory impacts Astragalus microcymbus in years with high rabbit populations. During one survey effort, observers found six rabbits in one of the draws they visited (Lyon 1990, p. 5), and another observer visited 10 A. microcymbus sites in a day and said that rabbit damage was heavy at nine of those sites (Dyer 1993, p. 2).

Several observers have suggested that rabbit herbivory can result in the death of Astragalus microcymbus. One observer suggested that 2 years of heavy rabbit use was more than A. microcymbus could tolerate because of all the dead plants they encountered in a heavy rabbit year (Lyon 1990, p. 5). Those plants that were not dead had only a few green leaves, again attributed to rabbit herbivory (Lyon 1990, p. 2). After 2 years of consecutive transect counts at a site another observer stated that many plants had died and attributed that death to overuse by rabbits (Sherwood 1994, p. 10). Observations of small mammal herbivory being a significant impact to the species occurs across the years (USFWS 2010a, pp. 1-4).

Rabbit and small mammal populations fluctuate widely (Korpimäki and Krebs 1996, pp. 754-764; Hanski et al. 2001, pp. 1501-1520). We have little information on how small mammal populations have changed within the range of Astragalus microcymbus over time, but the variability in observations from year to year and between sites suggest there are significant fluctuations and spatial variations

1-4).

Rabbit and small mammal populations fluctuate widely (Korpimäki and Krebs 1996, pp. 754-764; Hanski et al. 2001, pp. 1501-1520). We have little information on how small mammal populations have changed within the range of Astragalus microcymbus over time, but the variability in observations from year to year and between sites suggest there are significant fluctuations and spatial variations. For example in 1990, local authorities and those surveying for A. microcymbus stated the rabbit population was very large compared with other years; this year, herbivory of A. microcymbus was repeatedly observed (Lyon 1990, p. 2). Observations suggest that small mammal herbivory is impacting A. microcymbus, especially during years when small mammal populations are high.

Fencing to exclude small mammals was installed at monitoring plots in

Rabbit herbivory has been documented at several Astragalus microcymbus units, including Gold Basin Creek, South Beaver Creek 1, South Beaver Creek 2, and South Beaver Creek 3 (USFWS 2010a, pp. 1-4). Conversely, at several of the more isolated A. microcymbus units, Henry and South Beaver Creek 4, observers specifically mention the lack of rabbit herbivory relative to other areas (USFWS 2010a, pp. 1-4).

We are unsure of the long-term impact to Astragalus microcymbus over time from small mammal herbivory. Small mammal herbivory is significantly impacting seed set of A. microcymbus. Fewer seeds mean fewer opportunities for seedling and adult recruitment. In addition, small mammal herbivory occurs at most sites across the range of the species, and recent observations indicate that damage to plants is heavy. We have no information to either support or refute that rabbit herbivory levels are higher than historic levels; however, in light of other factors affecting the species and the limited range and small population level, impacts to A. microcymbus from herbivory can be large in years of high rabbit populations

the range of the species, and recent observations indicate that damage to plants is heavy. We have no information to either support or refute that rabbit herbivory levels are higher than historic levels; however, in light of other factors affecting the species and the limited range and small population level, impacts to A. microcymbus from herbivory can be large in years of high rabbit populations. Given this, we find small mammal herbivory to be a threat to the species.

Deer and Elk Herbivory

Like livestock use, overgrazing by deer and elk may cause local degradation of habitats (see “Livestock, Deer, and Elk Use of Habitat” above for a more thorough discussion). Here we address the actual eating of Astragalus microcymbus individuals as opposed to habitat degradation. We have little information on the impacts of deer and elk herbivory to A. microcymbus. Much of the deer and elk use of A. microcymbus habitat occurs during winter after the plants are no longer growing, thereby not affecting the plants, unless they are pulled up by the roots, which we assume would happen infrequently. One observer stated that the previous year's dried stalks of larger A. microcymbus plants showed almost universal use, and attributed this to wintering big game (Sherwood 1994, p. 17).

Although deer and elk use is high within Astragalus microcymbus habitat (see Deer and Elk Use above), most of the use occurs in the winter when A. microcymbus is dormant. We expect the effects of winter use to be minimal since, once dried, the previous year's growth is not important to an individual plant's success. We expect that some herbivory does occur since deer and elk will sometimes visit during the growing season. Because most use occurs in the winter when herbivory would not impact A. microcymbus, we do not consider deer and elk herbivory to be a threat now or in the foreseeable future

r use to be minimal since, once dried, the previous year's growth is not important to an individual plant's success. We expect that some herbivory does occur since deer and elk will sometimes visit during the growing season. Because most use occurs in the winter when herbivory would not impact A. microcymbus, we do not consider deer and elk herbivory to be a threat now or in the foreseeable future.

Livestock Herbivory

Livestock use may cause local degradation of habitats (see “Livestock, Deer, and Elk Use of Habitat” above for a more thorough discussion). Here we address the actual eating of Astragalus microcymbus individuals as opposed to habitat degradation. Observations on direct grazing impacts to Astragalus microcymbus vary. Heil and Porter (1990, p. 21) state that grazing animals are known to occasionally use this species as a forage plant. One observer reported the plant shows some resistance to grazing (CNHP 2010a, pp. 5-6). Livestock presence is reportedly rare on the steeper slopes where A. microcymbus resides (BLM 2010, p. 4). We believe we have seen herbivory of individuals in areas near salt licks, although we cannot be sure this was not small mammal herbivory (USFWS 2010, pers. comm.). Therefore, we do not consider the livestock herbivory to be a threat to the species now or in the foreseeable future.

Insect Herbivory

Grasshoppers (Orthopterans in the Acrididae and Tettigoniidae families) have been implicated as herbivores of Astragalus microcymbus (Dyer 1993, p. 2). Aphids have been documented on the plants at one A. microcymbus site (CNHP 2010a, p. 22). A small number of A. microcymbus individuals have been documented with insect webs within Gold Basin Creek Unit (Sherwood 1994, p. 7). Insect herbivory was measured as part of the life-history monitoring study. This study found no significant effects from insect herbivory on flowering individuals (DBG 2010a, p. 6). Therefore, we find that insect herbivory does not constitute a threat to A. microcymbus now or in the foreseeable future

viduals have been documented with insect webs within Gold Basin Creek Unit (Sherwood 1994, p. 7). Insect herbivory was measured as part of the life-history monitoring study. This study found no significant effects from insect herbivory on flowering individuals (DBG 2010a, p. 6). Therefore, we find that insect herbivory does not constitute a threat to A. microcymbus now or in the foreseeable future.

Disease

A fungus has been documented on less than 10 percent of the Astragalus microcymbus individuals at one monitoring transect (Sherwood 1994, p. 11). No other instances of disease are known. Therefore, we find that disease does not constitute a threat to A. microcymbus now or in the foreseeable future.

Summary of Factor C

Various herbivores have been documented at Astragalus microcymbus sites. Small mammal herbivory, especially from rabbits, has been documented at fairly high levels, and appears to be the only type of herbivory that is impacting the species at a low to moderate level. Exclusion research has found that small mammal herbivory was less, more individuals flowered, and there were more total fruits within fenced areas (DBG 2010a, p. 7). We expect small mammal herbivory to continue into the foreseeable future and fluctuate with small mammal populations. We do not believe that deer and elk herbivory, livestock herbivory, and insect herbivory constitute threats because they are only occasionally or minorly affecting A. microcymbus and are not expected to increase into the foreseeable future. Finally, we do not consider disease to be a threat because it is so rare. However, we do find that Astragalus microcymbus is threatened by predation now and these threats are expected to continue or increase in the foreseeable future.

Factor D. Inadequacy of Existing Regulatory Mechanisms

Under this factor, we examine whether threats to Astragalus microcymbus are adequately addressed by existing regulatory mechanisms. Existing regulatory mechanisms that could provide some protection for A

t Astragalus microcymbus is threatened by predation now and these threats are expected to continue or increase in the foreseeable future.

Factor D. Inadequacy of Existing Regulatory Mechanisms

Under this factor, we examine whether threats to Astragalus microcymbus are adequately addressed by existing regulatory mechanisms. Existing regulatory mechanisms that could provide some protection for A. microcymbus include: (1) Local land use laws, processes, and ordinances; (2) State laws and regulations; and (3) Federal laws and regulations. Regulatory mechanisms, if they exist, may preclude listing if such mechanisms are judged to adequately

An example of a regulatory mechanism is the terms and conditions attached to a grazing permit that describe how a permittee will manage livestock on a BLM allotment. They are nondiscretionary and enforceable, and would be considered a regulatory mechanism under this analysis. Other examples include city or county ordinances, State governmental actions enforced under State statute regulations, or Federal action under statute or regulation. Actions adopted by local groups, States, or Federal entities that are discretionary or are not enforceable, including conservation strategies and guidance, are typically not regulatory mechanisms. In this section we review actions undertaken by local, State, and Federal entities designed to reduce or remove threats to Astragalus microcymbus and its habitat.

Local Land Use Laws and Ordinances

We are aware of no local land use laws or ordinances that offer protection to Astragalus microcymbus. Neither the city of Gunnison nor the counties of Gunnison or Saguache have guidelines, zoning, or other mechanisms to protect the species.

State Laws and Regulations

No State regulations in Colorado protect Astragalus microcymbus. The State of Colorado has no laws protecting any rare plant species. Plants also are not included in the Colorado Wildlife Action Plan and do not qualify for funding under State Wildlife Grants

nor the counties of Gunnison or Saguache have guidelines, zoning, or other mechanisms to protect the species.

State Laws and Regulations

No State regulations in Colorado protect Astragalus microcymbus. The State of Colorado has no laws protecting any rare plant species. Plants also are not included in the Colorado Wildlife Action Plan and do not qualify for funding under State Wildlife Grants.

The State of Colorado's Natural Areas Program works to protect special resources in the State, although there are no regulatory enforcement mechanisms associated with the program. In 1997, the Colorado Natural Areas Program designated the South Beaver Creek Natural Area (CNAP 1997, pp. 1-7). The South Beaver Creek Natural Area was designated for all areas within the South Beaver Creek ACEC (CNAP 1997, p. 7). The Colorado Natural Areas Program provides a means by which Colorado's natural features and ecological phenomena can be identified, evaluated, and protected through a statewide system of natural areas (CNAP 1997, p. 1). The purpose of the South Beaver Creek Natural Area is to protect Astragalus microcymbus (CNAP 1997, p. 2).

Through this designation, the Colorado Natural Areas Program staff is entitled to visit the area at anytime and convey the results of these visits to the BLM, cooperate with the BLM on updating the Resource Management Activity Plan for the property, and provide a periodic report on the condition of the property (CNAP 1997, p. 3). In essence, this designation allows the Colorado Natural Areas Program to assist the BLM with its management. The Colorado Natural Areas Program has not been actively monitoring Astragalus microcymbus at the South Beaver Creek Natural Area. Therefore, this designation has, to-date, afforded little protection to the species. Given that the Colorado Natural Areas Program is increasing its conservation efforts, we expect the Natural Areas Program to become more active in the conservation of A

its management. The Colorado Natural Areas Program has not been actively monitoring Astragalus microcymbus at the South Beaver Creek Natural Area. Therefore, this designation has, to-date, afforded little protection to the species. Given that the Colorado Natural Areas Program is increasing its conservation efforts, we expect the Natural Areas Program to become more active in the conservation of A. microcymbus in the future but have no way of predicting what this will mean to the species.

The State of Colorado requires private landowners to control noxious (nonnative invasive) weeds. Plants considered noxious by the State of Colorado that are within or near Astragalus microcymbus' habitat include: Cheatgrass (List C), Canada thistle ( Cirsium arvense —List B), scentless chamomile ( Matriacaria perforata —List B), yellow toadflax ( Linaria vulgaris —List B), and Russian knapweed ( Acroptilon repens —List B) (Colorado Department of Agriculture [CDA] 2010, pp. 2-3). List B species are noxious weeds for which management plans are or will be developed and implemented to stop their spread (CDA 2010, p. 2). List C species are noxious weeds for which management plans are or will be developed and implemented to provide additional education, research, and biological control resources but for which the continued spread will not be halted (CDA 2010, p. 2). We have no information on how the noxious weed law is being implemented within the range of A. microcymbus. We do know that the Gunnison Watershed Weed Commission has been actively working to control and eradicate noxious weeds in Gunnison County but we have few specifics from this work (GWWC 2010, pp. 1-8). Therefore, we cannot assess the benefits to A. microcymbus.

Deer and elk populations are managed by the CDOW. We have no information to suggest that deer and elk use is being regulated to ensure Astragalus microcymbus and its habitat is not impacted by this use

ctively working to control and eradicate noxious weeds in Gunnison County but we have few specifics from this work (GWWC 2010, pp. 1-8). Therefore, we cannot assess the benefits to A. microcymbus.

Deer and elk populations are managed by the CDOW. We have no information to suggest that deer and elk use is being regulated to ensure Astragalus microcymbus and its habitat is not impacted by this use.

Federal Laws and Regulations

The BLM has promulgated regulations, policies, and guidelines to protect sensitive species on Federal lands, control wildfire and rehabilitate burned areas, and implement rangeland assessments, standards, and guidelines to assess rangeland health.

Astragalus microcymbus is included on the Colorado BLM's sensitive species list (BLM 2009c, p. 3). The management guidance afforded sensitive species under BLM Manual 6840—Special Status Species Management (BLM 2008) states that “Bureau sensitive species will be managed consistent with species and habitat management objectives in land use and implementation plans to promote their conservation and to minimize the likelihood and need for listing under the ESA” (BLM 2008, p. .05V). The BLM Manual 6840 further requires that Resource Management Plans (RMPs) should address sensitive species, and that implementation “should consider all site-specific methods and procedures needed to bring species and their habitats to the condition under which management under the Bureau sensitive species policies would no longer be necessary” (BLM 2008, p. 2A1). A. microcymbus has received some protections because of its sensitive status, including the establishment of the South Beaver Creek ACEC and limited money for survey and monitoring efforts. However, part of this ACEC is overlapped by the Hartman Rocks Recreation Area, which is resulting in some habitat loss, fragmentation, and degradation.

The Federal Land Policy and Management Act of 1976 mandates Federal land managers to develop and revise land use plans

nsitive status, including the establishment of the South Beaver Creek ACEC and limited money for survey and monitoring efforts. However, part of this ACEC is overlapped by the Hartman Rocks Recreation Area, which is resulting in some habitat loss, fragmentation, and degradation.

The Federal Land Policy and Management Act of 1976 mandates Federal land managers to develop and revise land use plans. The RMPs are the basis for all actions and authorizations involving BLM-administered lands and resources. They establish allowable resource uses, resource condition goals and objectives to be attained, program constraints and general management practices needed to attain the goals and objectives, general implementation sequences, and intervals and standards for monitoring and evaluating the plan to determine its effectiveness and the need for amendment or revision (43 CFR 1601.0-5(k)).

The RMPs provide a framework and programmatic guidance for activity plans, which are site-specific plans written to implement the RMP. Examples of activity plans include Allotment Management Plans that address livestock grazing, or other activity plans for oil and gas field development, travel management, and wildlife habitat management. Activity plan decisions normally require additional planning and National Environmental Policy Act (NEPA) analysis. The Gunnison Resource Area's RMP represe

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