# Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition to List Abronia ammophila, Agrostis rossiae, Astragalus proimanthus, Boechera (Arabis) pusilla, and Penstemon gibbensii as Threatened or Endangered; Proposed Rule

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URL: https://www.frixlaw.com/law-library/documents/fr%3A2011-13910

## Record

- **Collection:** Federal Register
- **Document type:** Proposed Rule
- **Published:** June 9, 2011
- **Citation:** 76 FR 33924

## Text

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R6-ES-2011-0023; MO 92210-0-0008-B2]

Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List
Abronia ammophila, Agrostis rossiae, Astragalus proimanthus, Boechera (Arabis) pusilla,
and
Penstemon gibbensii
as Threatened or Endangered

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Notice of 12-month petition finding.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), announce a 12-month finding on a petition to list
Abronia ammophila
(Yellowstone sand verbena),
Agrostis rossiae
(Ross' bentgrass),
Astragalus proimanthus
(precocious milkvetch),
Boechera
(
Arabis
)
pusilla
(Fremont County rockcress or small rockcress), and
Penstemon gibbensii
(Gibbens' beardtongue) as threatened or endangered, and to designate critical habitat under the Endangered Species Act of 1973, as amended (Act). After review of all available scientific and commercial information, we find that listing
A. ammophila, A. rossiae, A. proimanthus,
and
P. gibbensii
is not warranted at this time. However, we ask the public to submit to us any new information that becomes available concerning the threats to
A. ammophila, A. rossiae, A. proimanthus,
and
P. gibbensii
or their habitats at any time. After a review of all the available scientific and commercial information, we find that listing
B. pusilla
as threatened or endangered is warranted. However, currently listing
B. pusilla
is precluded by higher priority actions to amend the Federal Lists of Endangered and Threatened Wildlife and Plants. Upon publication of this 12-month petition finding, we will add
B. pusilla
to our candidate species list. We will develop a proposed rule to list
B. pusilla
as our priorities allow. We will make any determinations on critical habitat during development of the proposed listing rule. In any interim period, we will address the status of the candidate taxon through our annual Candidate Notice of Review.

DATES:

The finding announced in this document was made on June 9, 2011.

ADDRESSES:

This finding is available on the Internet at
http://www.regulations.gov
at Docket Number FWS-R6-ES-2011-0023. Supporting documentation used in preparing this finding is available for public inspection, by appointment, during normal business hours at the U.S. Fish and Wildlife Service, Wyoming Ecological Services Field Office, 5353 Yellowstone Road, Suite 308A, Cheyenne, WY 82009. Please submit any new information, materials, comments, or questions concerning this finding to the above address.

FOR FURTHER INFORMATION CONTACT:

R. Mark Sattelberg, Field Supervisor, Wyoming Ecological Services Field Office (see
ADDRESSES
); by telephone at 307-772-2374; or by facsimile at 307-772-2358. If you use a telecommunications device for the deaf (TDD), please 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: (1) Not warranted, (2) warranted, or (3) warranted, but the 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
.

Previous Federal Actions

Federal action for
Agrostis rossiae
and
Astragalus proimanthus
began as a result of section 12 of the original Act, 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. That document lists
A. rossiae
as a threatened species and
A. proimanthus
as an endangered species (House Document 94-51, pp. 57, 90, 163). On July 1, 1975, we published a notice in the
Federal Register
(40 FR 27823) accepting the Smithsonian Institution report as a petition within the context of section 4(c)(2) (petition provisions are now found in section 4(b)(3) of the Act), and giving notice of the Service's intention to review the status of the plant taxa listed therein.

As a result of that review, we published a proposed rule on June 16, 1976, in the
Federal Register
(41 FR 24523) to determine endangered status pursuant to section 4 of the Act for approximately 1,700 vascular plant taxa, including
Astragalus proimanthus.
This list of plant taxa was assembled based on 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 section 4(f)(5) of the Act required that all proposals over 2 years old be withdrawn. However, proposals already over 2 years old were given a 1-year grace period. On December 10, 1979, we 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. This removed both
A. proimanthus
and
Agrostis rossiae
from proposed status, but retained both species as candidate plant taxa that “may qualify for listing under the Act.”

On December 15, 1980, we published a current list of those plant taxa native to the United States being considered for listing under the Act; this identified both
Agrostis rossiae
and
Astragalus proimanthus
as category 1 taxa (45 FR 82480). The Service defined category 1 taxa as a taxonomic group for which we presently had sufficient information on hand to support the biological appropriateness of these taxa being listed as threatened or endangered species (45 FR 82480). On November 28, 1983,
A. rossiae
was lowered to a category 2 taxon “currently under review,” whereas
A. proimanthus
was moved to the “taxa no longer under review” list, and given a 3C rank, indicating the species was more abundant or widespread than previously believed or not subjected to any identifiable threat (48 FR 53640). We defined category 2 taxa as those for which we had information at that time that indicated proposing to list was possibly appropriate, but for which substantial data on biological

vulnerability and threat(s) was not currently known or on file to support proposed rules.
Boechera
(formerly
Arabis
)
pusilla
and
Penstemon gibbensii
were added as category 2 taxa during the same review (48 FR 53640). These four species retained the same ranking for the subsequent review on September 27, 1985 (50 FR 39526). The February 21, 1990, list kept
A. rossiae, B. pusilla,
and
P. gibbensii
as category 2 taxa, and reverted
A. proimanthus
back to a category 2 taxon (55 FR 6184).

The September 30, 1993, review changed the status of
Boechera pusilla
to a category 1 species (58 FR 51144). This review added a “status trend” column. Each species was identified as increasing (I), stable (S), declining (D), or unknown (U). The 1993 review added
Abronia ammophila
and assigned it a 2U rank, moved
Boechera pusilla
up to a 1D rank, and listed
Agrostis rossiae
as 2U,
Astragalus proimanthus
as 2S, and
Penstemon gibbensii
as 2U (58 FR 51144).

On February 28, 1996, we proposed discontinuing the designation of category 2 species as candidates due to the lack of sufficient information to justify issuance of a proposed rule (61 FR 7596). This proposal included eliminating candidate status for four of the five species addressed in this finding; only
Boechera pusilla
was proposed to remain a candidate (61 FR 7596). This policy change was finalized on December 5, 1996, stating that the listing of category 2 species was not needed because of other lists already maintained by other entities such as Federal and State agencies (61 FR 64481).

On September 19, 1997, we published a notice of review that retained
Boechera pusilla
as a candidate species (62 FR 49398). However, on October 25, 1999, we published a notice of review that indicated our intent to remove several species, including
B. pusilla,
from the list of candidate species because evidence suggested that these taxa were either more abundant than previously believed or that the taxa were not subject to the degree of threats sufficient to warrant continuance of candidate status, issuance of a proposed listing, or a final listing (64 FR 57534). The change of status for
B. pusilla
was finalized on October 20, 2000, on the basis that regulatory mechanisms and changes to management of the associated land reduced or eliminated the threats facing
B. pusilla
and ensured the survival and conservation of this species (65 FR 63044).

On July 30, 2007, we received a formal petition dated July 24, 2007, from Forest Guardians (now WildEarth Guardians), requesting that we: (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 threatened or endangered. The petition identified 206 species as petitioned entities, including the 5 species we address in this status review. A species ranking of G1 is defined as a species that is critically imperiled across its entire range (or global range) (NatureServe 2010b, p. 3). A ranking of G1G2 means the species is either ranked as a G1 or a G2 species, with G2 defined as imperiled across its entire range (NatureServe 2010b, pp. 3-4). The petition incorporated all analysis, references, and documentation provided by NatureServe in its online database at
http://www.natureserve.org/
into the petition. The petition clearly identified itself as a petition and included the identification information, as required in 50 CFR 424.14(a). We sent a letter to the petitioners, dated August 24, 2007, acknowledging receipt of the petition and stating that, based on preliminary review, we found no compelling evidence to support an emergency listing for any of the species covered by the petition.

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 mountain-prairie species and one for southwest species. We subsequently published two initial 90-day findings on January 6, 2009 (74 FR 419), and February 5, 2009 (74 FR 6122). The February 5, 2009, finding determined that there was not substantial scientific or commercial information indicating that listing 165 of the 206 petitioned species in the mountain-prairie region may be warranted (74 FR 6122). Two additional species were evaluated in a January 6, 2009, 90-day finding (74 FR 419), and no determination was made on whether substantial information had been presented on the remaining 39 species included in the petition (74 FR 6122). The 5 species covered in this 12-month finding were among the remaining 39 species. An additional species was determined to qualify for candidate status (73 FR 75175; December 10, 2008). 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' petitions present substantial information indicating that the petitioned actions may be warranted for the remaining 38 mountain-prairie species by August 9, 2009.

On June 18, 2008, we received a petition from WildEarth Guardians dated June 12, 2008, to emergency list 32 species under the Administrative Procedure Act and the Endangered Species Act. Of those 32 species, 11 were included in the July 24, 2007, petition to be listed on a non-emergency basis. Although the Act does not provide for a petition process for an interested person to seek to have a species emergency listed, section 4(b)(7) of the Act authorizes the Service to issue emergency regulations to temporarily list a species. In a letter dated July 25, 2008, we stated that the information provided in both the 2007 and 2008 petitions and in our files did not indicate that an emergency situation existed for any of the 11 species. The Service's decisions whether to exercise its authority to issue emergency regulations to temporarily list a species are not judicially reviewable.
See Fund for Animals
v.
Hogan,
428 F.3d 1059 (DC Cir. 2005).

On August 18, 2009, we published a notice of 90-day finding (74 FR 41649) on the remaining 38 species from the petition to list 206 species in the mountain-prairie region of the United States as threatened or endangered under the Act. We found that the petition presented substantial scientific and commercial information for 29 of the 38 species, indicating that listing may be warranted for those species. The 5 species we address in this 12-month finding were included within these 29 species. We also opened a 60-day public comment period to allow all interested parties an opportunity to provide information on the status of the 29 species (74 FR 41649). The public comment period closed on October 19, 2009. We received 224 public comments. Of these, 38 specifically addressed
Abronia ammophila, Agrostis rossiae, Astragalus proimanthus, Boechera pusilla,
and
Penstemon gibbensii.
All information received has been carefully considered in this finding. This notice constitutes the 12-month finding on 5 of the 206 species identified in WildEarth Guardians' petition dated July 24, 2007, to list
Abronia ammophila, Agrostis rossiae, Astragalus proimanthus, Boechera pusilla,
and
Penstemon gibbensii
as threatened or endangered.

Summary of Procedures for Determining the Listing Status of Species

Review of Status Based on Five Factors

Section 4 of the Act (16 U.S.C. 1533) and implementing regulations (50 CFR part 424) set forth procedures for adding species to, removing species from, or reclassifying species on 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 these findings, information pertaining to each species in relation to the five factors provided in section 4(a)(1) of the Act is discussed below. In considering what factors might constitute threats to a species, we must look beyond the exposure of the species to a particular 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 during the status review, 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 by the Act. However, the identification of factors that could impact a species negatively may not be sufficient to compel a finding that the species warrants listing. The information must include evidence sufficient to suggest that the potential threat has the capacity (
i.e.,
it should be of sufficient magnitude and extent) to affect the species' status such that it meets the definition of endangered or threatened under the Act.

Findings

Distinct Population Segments

After considering the five factors, we assess whether each species is threatened or endangered throughout all of its range. Generally, we next consider in our findings whether a distinct vertebrate population segment (DPS) or any significant portion of the species' range meets the definition of endangered or is likely to become endangered in the foreseeable future (threatened).

Section 3(16) of the Act defines a species to include only a vertebrate species as a DPS. Therefore, the Service's Policy Regarding the Recognition of Distinct Vertebrate Population Segments Under the Endangered Species Act (DPS Policy) (61 FR 4722; February 7, 1996) is not applicable to plants and no population segments under the review could qualify as DPSs under the Act. Although the Service's DPS Policy is not applicable to plants, we do determine in our findings whether a plant species is threatened or endangered in a significant portion of its range.

Significant Portion of the Range

In determining whether a species is threatened or endangered in a significant portion of its range, we first identify any portions of the range of the species that warrant further consideration. The range of a species can theoretically be divided into portions an infinite number of ways. However, there is no purpose to analyzing portions of the range that are not reasonably likely to be both (1) significant and (2) threatened or endangered. To identify only those portions that warrant further consideration, we determine whether there is substantial information indicating that: (1) The portions may be significant, and (2) the species may be in danger of extinction there or likely to become so within the foreseeable future. In practice, a key part of this analysis is whether the threats are geographically concentrated in some way. If the threats to the species are essentially uniform throughout its range, no portion is likely to warrant further consideration. Moreover, if any concentration of threats applies only to portions of the species' range that are not significant, such portions will not warrant further consideration.

If we identify portions that warrant further consideration, we then determine whether the species is threatened or endangered in these portions of its range. Depending on the biology of the species, its range, and the threats it faces, the Service may address either the significance question or the status question first. Thus, if the Service considers significance first and determines that a portion of the range is not significant, the Service need not determine whether the species is threatened or endangered there. Likewise, if the Service considers status first and determines that the species is not threatened or endangered in a portion of its range, the Service need not determine if that portion is significant. However, if the Service determines that both a portion of the range of a species is significant and the species is threatened or endangered there, the Service will specify that portion of the range as threatened or endangered under section 4(c)(1) of the ESA.

Evaluation of the Status of Each of the Five Plant Species

For each of the five species, we provide a description of the species and its life-history and habitat, an evaluation of listing factors for that species, and our finding that the petitioned action is warranted or not for that species. We follow these descriptions, evaluations, and findings with a discussion of the priority and progress of our listing actions.

Species Information for
Abronia ammophila

Species Description

Abronia ammophila
is a low-growing, mat-forming perennial herb (Clark
et al.
1989, p. 7; Fertig 1994, unpaginated; (National Park Service (NPS) 1999b, p. 3; Fertig 2000b, unpaginated; Saunders and Sipes 2006, p. 76).
A. ammophila
is a highly restricted endemic (occurring only in one location or region) to the Yellowstone Plateau (NPS 1999a, p. 1). In addition to the common name of Yellowstone sand verbena,
A. ammophila
has been called Tweedy's sand verbena (Clark
et al.
1989, p. 7; Marriott 1993, p. 1) and Wyoming sand verbena (Integrated Taxonomic Information System 2010a, unpaginated).

Abronia ammophila
has a large taproot (primary root that grows vertically downward, not highly branched) that can be over 0.5 meter (m) (1.6 feet (ft)) in length, which helps the plant root into the loose sand (Whipple 1999, p. 3; Whipple 2002, p. 257; Saunders and Sipes 2004, p. 9). Its stems can grow up to 2 to 4 decimeters (dm) (0.66 to 1.31 ft) in length; however, this plant is only 2.5 to 10.2 centimeters (cm) (1 to 4 inches (in.)) tall (Rydberg 1900, p. 137; Galloway 1975, p. 344; Fertig 1994, unpaginated; NPS 1999b, p. 3; Fertig 2000b, unpaginated; NPS 2000, unpaginated).
A. ammophila
is covered by sticky glands, which result in the plants being covered with sand (Coulter and Nelson 1909, p. 175; NPS 1999b, p. 3; NPS 2000, unpaginated; Whipple 2002, pp. 257-258; Saunders and Sipes 2006, p. 76). The leaf blades are succulent (fleshy) and oval or diamond-shaped with smooth edges (Fertig 1994, unpaginated; NPS 1999b, p. 3).

The flowers of
Abronia ammophila
are whitish to light pink or light green and grow in a capitulum (head-like group of flowers) typically containing 4 to 21 flowers (Saunders and Sipes 2006, p. 79). The flowers are hermaphroditic (possessing both male and female reproductive organs) (Saunders and Sipes 2004, p. 9; 2006, p. 76). As with other members of the Nyctaginaceae (the Four O'Clock) family,
A. ammophila
lacks true petals (Saunders and Sipes 2004, p. 9; 2006, p. 76).

Discovery and Taxonomy

Frank Tweedy made the first collection of
Abronia ammophila
in 1885; however, he labeled it as
Abronia villosa
(desert sand verbena). The collection was from the sandy beaches on the north side of Yellowstone Lake at the mouth of Pelican Creek (Tweedy 1886, p. 59).
A. villosa
is a common purple-flowered species of the American southwest (Whipple 2002, p. 256). In 1900, Per Axel Rydberg determined that Tweedy's sample was sufficiently different from other
Abronia
to warrant recognition as a unique species; he named it
Abronia arenaria
(coastal sand verbena) (NPS 1999b, p. 2; Whipple 1999, p. 3; 2002, p. 256). However, the name
A. arenaria
had previously been used (NPS 1999b, p. 2; Whipple 1999, p. 2; 2002, p. 256). E.L. Greene proposed the name
A. ammophila
for the Yellowstone sand verbena species (Greene 1900 as cited in Whipple 2002, p. 256).

The name
Abronia ammophila
was formally recognized (Coulter and Nelson 1909, p. 175); however, midway through the 20th century it was combined with
Abronia fragrans
(snowball sand verbena), a widespread western species (Hitchcock
et al.
1964 and Despain 1975 as cited in Whipple 2002, p. 257). In 1975, a study of the
Abronia
genus determined that the Yellowstone species was unique (Galloway 1975, p. 344; NPS 1999b, p. 3; Whipple 2002, p. 257). Plant material collected from scrub communities of sandy hills near Big Piney, Sublette County, Wyoming, also was included under
A. ammophila
(Galloway 1975, p. 344, NPS 1999b, p. 3; Whipple 2002, p. 257). Further examination revealed that the specimens from Sublette County are actually
Abronia mellifera
(white sand verbena) (Marriott 1993, pp. 6, 9; Fertig 1994, unpaginated).

Abronia ammophila
is a member of the New World plant family Nyctaginaceae that typically lives in warmer climates, such as deserts and tropical areas (NPS 2000, unpaginated). The genus
Abronia
contains approximately 20 to 30 species (NPS 1999b, p. 2, Flora of North America 2010a, unpaginated). Most
Abronia
occur in the western United States and Mexico, but some extend into southern Canada and east into the Great Plains and Texas (NPS 1999b, p. 2).
A. ammophila
is similar to
Abronia mellifera
(Fertig 1994, unpaginated) and
Abronia fragrans
(Flora of North America 2010, unpaginated). We recognize
A. ammophila
as a valid species and a listable entity.

Biology and Life History

Abronia ammophila
starts to flower by the middle of June and continues producing flowers until a frost occurs that kills its aboveground parts, usually in late August or early September (NPS 1999b, p. 6; Whipple 1999, p. 3; NPS 2000, unpaginated; Whipple 2002, p. 258). This extended blooming period is unusual in comparison to other plants in Yellowstone National Park (YNP) (Whipple 1999, p. 3). Additionally, unlike many of its associated species,
A. ammophila
continues to flower vigorously even after setting fruit (NPS 1999b, p. 6; Whipple 2002, p. 258).

Abronia ammophila
is visited by several orders of insects (Saunders and Sipes 2004, p. 10; 2006, p. 80). The most frequent visitors to
A. ammophila
are lepidopterans (butterflies and moths) (Saunders and Sipes 2004, p. 10; 2006, p. 80). Even though
Abronia ammophila
is visited by a diverse range of pollinators, the total number of pollinator visitations is extremely low (Saunders and Sipes 2006, p. 81). The low level of pollinator visits may be offset by
A. ammophila
exhibiting a mixed-mating system (Saunders and Sipes 2004, pp. 6, 10, 12; 2006, p. 82). In addition to cross-pollination facilitated by pollinators,
A. ammophila
is able to self-pollinate with or without a pollen vector (Saunders and Sipes 2004, pp. 6, 10, 12; 2006, pp. 80-82; Whipple 2010b, pers. comm.). Self-pollination is highly likely due to the floral morphology (the structure of the flower) and the functional phenology (life cycle) of
A. ammophila
(Saunders and Sipes 2006, p. 81).

Abronia ammophila
is capable of producing large numbers of flowers (Saunders and Sipes 2004, p. 13). Seed dispersal mechanisms of
Abronia ammophila
have not been extensively studied. Primary seed dispersal appears to occur beneath the parent plant (Saunders and Sipes 2006, p. 79). Seeds also accumulate in depressions of the sand, where the wind has blown them (NPS 1999b, p. 6; Whipple 2002, p. 258). The sticky surface of the seeds may facilitate dispersal, for example on the feet of waterfowl (NPS 1999b, pp. 6-7; Whipple 2002, p. 258). Water also may facilitate dispersal (Saunders and Sipes 2006, p. 79). As
A. ammophila
occurs in locations that are not located adjacent to each other, there appears to be an effective method of seed dispersal (NPS 1999b, pp. 6-7; Whipple 2002, p. 258). However, the longevity of
A. ammophila
seeds in the seed bank in unknown (NPS 1999b, p. 7; Whipple 2002, p. 258).

Habitat

Abronia ammophila
is endemic to YNP, within Park and Teton Counties of Wyoming (Whipple 2002, p. 256; Fertig 2000b, unpaginated; Saunders and Sipes 2006, p. 76). Specifically,
A. ammophila
occurs around Yellowstone Lake typically within 40 m (131.2 ft) of the shoreline (NPS 1999b, p. 5; Whipple 1999, p. 3; Fertig 2000b, unpaginated; Whipple 2002, p. 262). The plant has been found up to 60 m (196.9 ft) inland and up to approximately 10 m (32.8 ft) above the high-water line (NPS 1999b, p. 5; Whipple 1999, p. 3; Fertig 2000b, unpaginated; Whipple 2002, p. 262).
A. ammophila
generally occurs above the high-water mark; no plants grow in areas that are regularly inundated (NPS 1999b, p. 5; Whipple 1999, p. 3; 2002, p. 262). Yellowstone Lake is a high-elevation (2,360 m (7,742 ft)), freshwater lake that was formed by volcanic activity (Pierce
et al.
2007, pp. 131-132; NPS 2006a, unpaginated). The lake level was originally 61 m (200 ft) higher than its present level, and the level is not entirely stable (Pierce
et al.
2007, pp. 131-132; NPS 2006a, unpaginated).
A. ammophila
appears to be able to adapt to the continually changing boundaries of its habitat as defined by Yellowstone Lake's fluctuations.

Occurring between the area of beach affected by wave action and the more densely vegetated areas inland,
Abronia ammophila
prefers open, sunny, sparsely vegetated sites (NPS 1999b, p. 5; Whipple 2002, p. 262; Saunders and Sipes 2006, p. 77). Associated vegetative species include
Phacelia hastata
(silver-leaf scorpion-weed),
Rumex venosus
(veiny dock),
Polemonium pulcherrimum
(Jacob's-ladder), and
Lupinus argenteus
(silvery lupine)

(NPS 1999b, p. 5; Whipple 2002, p. 262; Saunders and Sipes 2006, p. 77).
A. ammophila
loses its competitive advantage on more stable soils or in areas where
Artemisia tridentata
(big sagebrush)

or
Eriogonum umbellatum
(sulfur flower buckwheat) occur (Whipple 2002, p. 262; Saunders and Sipes 2006, p. 77).

Abronia ammophila
occurs at four locations around Yellowstone Lake; these locations are identified as North

Shore, Rock Point, Pumice Point, and South Arm (NPS 1999a, pp. 3-6; NPS 1999b, pp. 4-5; Whipple 2002, p. 262). These populations cover an area of 0.6 hectares (ha) (1.48 acres (ac)) (Whipple 2011, pers. comm.). The populations all occur in loose, unconsolidated (loosely arranged) sand with a minimal amount of fines (powdered material), gravel, or organic matter (NPS 1999b, p. 5; Whipple 2002, p. 262; Saunders and Sipes 2006, p. 77). All sites are located on beach sand except the Pumice Point site, which occurs on black sand (NPS 1999b, p. 5; Whipple 2002, p. 262). Some of the populations occur in horseshoe-shaped, sandy depressions (blowouts) (NPS 1999a, p. 3; 1999b, p. 5; Whipple 2002, p. 262; Saunders and Sipes 2006, p. 77). Additionally, the largest subpopulation in the North Shore area—the “Thermal” site—is located adjacent to a small thermal barren (area where no vegetation grows) (NPS 1999a, p. 6; NPS 1999b, p. 6). This area hosts an extremely dense population of
Abronia ammophila
with some of the largest individuals (NPS 1999b, p. 6).
A. ammophila
is able to coexist with thermal influences; however, most of the populations grow on ground that is not thermally influenced (NPS 1999a, p. 6).

Distribution and Abundance

Herbarium records show that
Abronia ammophila
was previously more widely distributed along the northern shore of Yellowstone Lake (NPS 1999b, p. 9; Whipple 2002, p. 258). Locations such as 0.40 kilometer (km) (0.25 mile (mi)) west of the mouth of Pelican Creek and several locations near the current Fishing Bridge development have been recorded as collection locations of
A. ammophila
(NPS 1999b, p. 9; Whipple 2002, pp. 258-259). Many additional areas of the northern shoreline provide suitable habitat for
A. ammophila,
such as west of Pelican Creek to the outlet of the Yellowstone River and Mary Bay (NPS 1999b, p. 9; Whipple 2002, p. 259; Whipple 2010a, pers. comm.). Construction of the East Entrance Road and the Fishing Bridge campground, an area that was near the current parking area for the Fishing Bridge Museum, as well as higher human use may have extirpated populations of
A. ammophila
in these areas (NPS 1999b, pp. 8-9; Whipple 2002, pp. 258-259; Whipple 2010a, pers. comm.).

Table 1 below presents available information regarding the four populations of
Abronia ammophila.
The 1998-1999 survey was a rigorous population count (NPS 1999a, entire). The other years were generally estimates, except for some of the smaller populations where an exact count was easily obtained (Correy 2009, entire; Whipple 2010d, pers. comm.).

Table 1—Population Estimates of Abronia ammophila

Population
(year of discovery)

Estimated numbers (year)

North Shore (prior to 1998)

Approx. 1,000 (early 1990s).
7,978 (1998-1999) rigorous count.
Approx. 3,600 (2010).

Rock Point (1998)

325 (1998).
120 (2009).

Pumice Point (1998)

22 (1998).
1 (2001).
5 (2009).
24 (2010).

South Arm (1998)

1 (1998).
3 (2005).
2 (2010).

Totals

1,000 (early 1990s) (only North Shore known).
8,326 (1998-1999) rigorous count.
2,728 (2009) estimate.
3,626 (2010) estimate.

References: NPS 1999a, Appendix A; Corry 2009, Table 1; Whipple 2002, p. 259; 2010d pers. comm.

The majority of
Abronia ammophila
is found in the North Shore population scattered along a 2.41-km (1.5-mi) stretch of beach on the northern shoreline of Yellowstone Lake between the mouth of Pelican Creek and Storm Point (NPS 1999a, p. 3; 1999b, p. 4; Correy 2009, p. 2). This population contains 95 percent or more of all
A. ammophila
(NPS 1999a, pp. 2, Appendix A; Whipple 2002, p. 264; Correy 2009, p. 4). Prior to surveys conducted between 1995 and 1999, the North Shore population of
A. ammophila
was the only known population (NPS 1999a, p. 3; Correy 2009, p. 2). Of the additionally discovered sites, two are located on the west shore of Yellowstone Lake: One at Rock Point, and one at a picnic area 1.6 km (1 mi) west of Pumice Point (NPS 1999a, p. 5; NPS 1999b, p. 4). Additionally, a single plant was found during surveys on the east shore of the South Arm (NPS 1999a, p. 5). Not all suitable habitat within YNP has been surveyed (NPS 1999a, pp. 6-7).

Casual surveys of the North Shore area in the early 1990s estimated the population to be around 1,000 plants (Correy 2009, pp. 1-2), with the majority of the plants of a large-size class representing mature, older plants (NPS 1999a, p. 1; 1999b, p. 7). No seedlings were observed (NPS 1999b, p. 7). Extensive surveys during the 1998-1999 field seasons conservatively estimated the North Shore population to consist of 7,978
Abronia ammophila
plants, with 45 percent of the population represented by young recruitment within the prior 2 years (recruit and medium class plants) (NPS 1999a, p. 1). The record high lake levels of 1996 and 1997 appeared to improve the habitat conditions for
A. ammophila
by eroding the southern edge of the stabilized sand along the northern shoreline (NPS 1999b, p. 7; Whipple 2002, p. 265). Although this erosion washed away part of the existing habitat, it also improved conditions for recruitment of seedlings (NPS 1999b, p. 7; Whipple 2002, p. 265).

During the 2009-2010 field season, surveys of the North Shore population yielded an approximate count of 3,600
A. ammophila
plants (Correy 2009, p. 3; Whipple 2010d, pers. comm.; Whipple 2011, pers. comm.). The North Shore population can be split into four subpopulations (Correy 2009, p. 2). Two of these subpopulations had comparable population counts during both the 1998-1999 survey and the 2009-2010 estimate (Correy 2009, pp. 3-4). The remaining two subpopulations, the Thermal and Long Skinny groups, had decreased in both total area populated and total number of plants (Correy 2009, p. 5). The central portion of the Thermal group is now bare or mostly bare sand due to increased ground temperatures (due to changes within the Yellowstone geothermal basin), ground subsidence, increased scouring during storms, or a combination of such factors (Correy 2009, p. 5). The Long Skinny group also may have been affected by increased ground temperatures, particularly on the western end; furthermore, some of the habitat may have eroded (Correy 2009, p. 5). Additional factors potentially affecting the low population count include many years of drought (Whipple 2002, p. 265; Correy 2009, pp. 5-6) and lack of rigorous survey methods (Correy 2009, pp. 5-6).

The Rock Point and Pumice Point
Abronia ammophila
populations were accurately counted in 1998 and 2009 (Correy 2009, Table 1). In 1998, the Rock Point population consisted of 324 individual plants; the 2009 survey counted 120 individual plants (NPS 1999a, p. 6; Correy 2009, Table 1). An area of Rock Point surveyed in 1998 had no
A. ammophila
in June, but contained many medium-sized plants later in the summer (NPS 1999a, p. 6). The Pumice Point population consisted of 22 plants in 1998, whereas only 5 were counted in 2009 (NPS 1999a, p. 6; Correy 2009,

Table 1). In 1998, the Pumice Point population contained a higher percentage of large (diameter greater than or equal to 5 up to 30 cm (2 up to 11.8 in.)) and very large (diameter greater than or equal to 30 cm (11.8 in.)) plants when compared to the North Shore population distribution (NPS 1999a, p. 6). Additionally, the Pumice Point population contained 24 plants in the 2010 field survey (Whipple 2010e, pers. comm.), which is comparable to the 1998 population count.

The South Arm population contained only one large
Abronia ammophila
plant when it was discovered in 1998 (NPS 1999a, p. 6). When this site was revisited in 2005, the large individual found in 1998 was no longer present, but three small
A. ammophila
plants were present (Correy 2009, p. 2). Additionally, during the 2010 field survey, this population consisted of two plants (Whipple 2010e, pers. comm.).

Dead and dying plants were counted during the 1998-1999 field surveys. Dead and dying
Abronia ammophila
plants accounted for 1.3 percent of the total population (NPS 1999a, Appendix A). Of the dead
A. ammophila
plants, many were large individuals; however, some were failed seedlings (NPS 1999b, p. 7). The majority of dead and dying plants did not display obvious causes of mortality; they were interspersed throughout the communities (NPS 1999b, p. 7). Additionally, stressed
A. ammophila
plants are able to recover and put out new growth later in the season (NPS 1999b, p. 7).

The Wyoming Natural Diversity Database (WNDD) has designated
Abronia ammophila
as a plant species of concern with ranks of G1 and S1 (Heidel 2007, p. 1). This designation indicates that
A. ammophila
is considered to be critically imperiled because of extreme rarity (
i.e.,
often less than five occurrences (a location where a plant or plants has been recorded)) or because some factor makes it highly vulnerable to extinction both at the global and State level; however, this ranking does not grant
A. ammophila
any special status under State legislation (WNDD 2009, unpaginated; WNDD 2010, unpaginated). Since
A. ammophila
is endemic to Wyoming, the Wyoming occurrences encompass the entire global range. Additionally, YNP considers
A. ammophila
to be a sensitive species of concern; therefore, it evaluates effects to this species in conjunction with any project or action that has the potential to affect the plant (Whipple 2011, pers. comm.).

Trends

Natural fluctuations in the
Abronia ammophila
population from year to year or even within a season are not understood (Correy 2009, p. 6). From the first population estimates of the North Shore population in the early 1990s to the more rigorous survey conducted in 1998-1999, there was extensive recruitment and the
A. ammophila
population increased approximately 87 percent (NPS 1999a, p. 1; Correy 2009, pp. 6, Table 1). Notably, 1996 and 1997 had high precipitation, with resultant high lake levels (NPS 1999a, p. 2). The 1998-1999 surveys recorded approximately 20 percent of the population to be seedlings or recruit size class (NPS 1999a, Appendix A). The 2009 population estimate of the North Shore populations shows a decrease from the 1998-1999 survey (Correy 2009, Table 1). However, the 1998-1999 survey was an exact count, whereas the 2009 was an estimate. Additionally, the subsequent 2010 population estimate shows a slight increase in the population size compared to the 2009 population estimate (Whipple 2010e, pers. comm.). Hypotheses for population fluctuations are changing thermal activity of the underlying area, ground subsidence, changing precipitation levels, and human and animal activity (Correy 2009, pp. 5-6). The
A. ammophila
population seems to be stable within the parameters of a population that lives in an unstable habitat that fluctuates with wave action and weather (Whipple 2010a, pers. comm.).

Five Factor Evaluation for
Abronia ammophila

Information pertaining to
Abronia ammophila
in relation to the five factors provided in section 4(a)(1) of the Act is discussed below.

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

Potential factors that may affect the habitat or range of
Abronia ammophila
are discussed in this section, including: (1) Development, (2) trampling, (3) nonnative invasive plants, (4) climate change, and (5) drought.

Development

Abronia ammophila
occurs entirely inside YNP, which limits potential threats to its habitat. By statute, regulation, and policy, YNP conserves wildlife and habitat; preserves and maintains biological processes, ecosystem components, and ecological integrity; controls invasive plants; and protects and monitors populations of sensitive plants and animals (See
Yellowstone National Park
under
Factor D. The Inadequacy of Existing Regulatory Mechanisms
in this Five Factor Evaluation for
Abronia ammophila
section). YNP was established prior to the States in which it is located (Mazzu 2010, pers. comm.; Whipple 2010e, pers. comm.). This means that YNP owns not only the land, but also the mineral rights; therefore, energy development is not a threat (Mazzu 2010, pers. comm.; Whipple 2010e, pers. comm.). Construction of new roads, trails, or structures within YNP is rare, with reconstruction of existing features occurring occasionally. When new construction or reconstruction occurs in areas where there are sensitive species, YNP analyzes and carries out construction in a manner that minimizes adverse effects.
A. ammophila
populations are located a sufficient distance from roads; therefore, road reconstruction does not impact any of the
A. ammophila
populations (Whipple 2010e, pers. comm.).

As noted above (see Distribution and Abundance),
Abronia ammophila
has been extirpated in some areas in which there is no longer habitat due to the construction of roads or structures. However, the construction in these areas occurred prior to YNP identifying
A. ammophila
as a species of conservation concern. Now, when new construction or reconstruction occurs, YNP analyzes and carries out construction in a manner that avoids adverse effects to sensitive species. Additionally, projects must be accompanied by a Resource Compliance Checklist that requires the evaluation of any potential impacts to resources including rare plants; if there are impacts, mitigation measures are developed (Schneider 2010, pers. comm.). The majority of YNP remains undeveloped, and we have no information that this will change; therefore, we do not consider development to be a threat to the species now or in the foreseeable future.

Trampling

Trampling of
Abronia ammophila,
by both humans and wildlife, is a potential concern at most sites (Whipple 2010a, pers. comm.). The
Abronia
genus is vulnerable to disturbance by trampling (NPS 1999b, p. 8; Whipple 2010e, pers. comm.). Trampling is frequently indicated as a threat to
A. ammophila
(
e.g.,
NPS 1999a; 1999b); however, studies that seek to document trampling indicate that there is very little foot traffic actually impacting the populations of
A. ammophila
(NPS 1999a, pp. 2, 5).

The North Shore population is located in one of the least visited portions of the north side of Yellowstone Lake's shoreline (NPS 1999b, p. 8). A large wetland restricts access to this site from the west (NPS 1999b, p. 8). The Storm Point Trail approaches the east end of the North Shore population, and visitors occasionally walk down the beach toward this population (NPS 1999b, p. 8). The YNP plans to install a sign just past the Storm Point Trail requesting that visitors remain near the water and avoid sensitive vegetation areas (Schneider 2010, pers. comm.).

The Pelican Creek Nature Trail is also near the North Shore population (Schneider 2010, pers. comm.). No plants currently occur in this area; however, it is historical habitat (Whipple

2010a, pers. comm.; Schneider 2010, pers. comm.). YNP is currently considering conservation measures, including closing all or part of this trail to protect the potential habitat (Whipple 2010a, pers. comm.; Schneider 2010, pers. comm.). A final decision, on this trail, has not been made at this time (Whipple 2011, pers. comm.).

The Pumice Point population of
Abronia ammophila
is located near an unmarked picnic area; the plants are located within 10 m (32.8 ft) of the picnic tables (NPS 1999b, p. 8). This area is currently unsigned (not marked as a picnic area from the main road), and the entrance is inconspicuous (Whipple 2010c, pers. comm.). Additionally, the
A. ammophila
in this area may be benefiting from the disturbance; if foot traffic did not occur, the area might be more densely vegetated and not available as habitat for
A. ammophila
(NPS 1999b, p. 8; Whipple 2010c, pers. comm.).

The two remaining populations are in areas with little visitation (NPS 1999b, p. 8). The Rock Point population is approximately a half-hour walk from the closest access point (Whipple 2010c, pers. comm.). The South Arm population is accessible by boat, with a backcountry campsite located about 200 m (656.2 ft) from the population (Whipple 2010c, pers. comm.). This backcountry campsite has no trail access (Whipple 2010c, pers. comm.).

YNP has received approximately 3 million visitors a year for the past 20 years; visitation was over 3 million for 11 of those years (NPS 2010a, unpaginated). From January to September of 2010, YNP received 3.4 million visitors, an increase of 8.7 percent over the previous year (NPS 2010b, unpaginated). Even with increases to visitation, we have no information indicating that the number of visitors correlates with increased trampling of
Abronia ammophila
populations to a level that poses a threat to the species.

Wildlife trampling, particularly by ungulates, is occasionally indicated as a concern (Whipple 2010a, pers. comm.) We believe that these anecdotal observations do not add up to routine impacts on a scale that would cause the species to be threatened or endangered. Additionally, we believe that trampling by wildlife represents a natural ecological interaction in YNP that the species would have evolved with and poses no threat to long-term persistence.

In summary, the populations of
Abronia ammophila
are located in areas of YNP that do not receive the bulk of visitor traffic. When surveys have attempted to document trampling by humans, observers had determined that the impact is minor. We have only anecdotal evidence of wildlife trampling. Therefore, we have no information indicating that trampling by either humans or wildlife is a threat to the species now or in the foreseeable future.

Nonnative Invasive Plants

After habitat loss, the spread of nonnative invasive species is considered the second largest threat to imperiled plants in the United States (Wilcove
et al.
1998, p. 608). Nonnative invasive plants alter 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 (D'Antonio and Vitousek 1992, pp. 74-75; DiTomaso 2000, p. 257; Mooney and Cleland 2001, p. 5449; Levine
et al.
2003, p. 776; Traveset and Richardson 2006, pp. 211-213).

As of 2010, YNP has documented 218 nonnative plant species occurring within its boundaries (NPS 2010e, p. 1). Encroachment of invasive plants may potentially affect
A. ammophila,
as this species prefers open, sparsely vegetated sites and does not compete well in areas that are more densely vegetated.

Currently, nonnative invasive plants have affected only a few sites occupied by
Abronia ammophila
(NPS 1999b, p. 8; Whipple 2010a, pers. comm.). The invasive grass
Bromus tectorum
(cheatgrass) has been noted in the vicinity of the North Shore population, and
Cirsium arvense
(Canada thistle) occurs near the Rock Point population (Whipple 2010a, pers. comm.). Additionally, some
B. tectorum
was documented around the Storm Point population (NPS 1999b, p. 8). To combat these occurrences, YNP has an exotic vegetation management plan in place that emphasizes prevention, education, early detection and eradication, control, and monitoring (Olliff
et al.
2001, entire).

In summary, nonnative invasive plants occur within YNP; however, the majority of these species do not impact the habitat of
Abronia ammophila.
A few nonnative invasive species have been documented near the habitat of
A. ammophila.
These species are being monitored and the National Park System (NPS) has mechanisms in place to help control these encroachments.

We have no information indicating that nonnative invasive species are modifying the species habitat to the extent that it represents a threat to the species now or in the foreseeable future.

Climate Change

The Intergovernmental Panel on Climate Change (IPCC) was established in 1988 by the World Meteorological Organization and the United Nations Environment Program in response to growing concerns about climate change and, in particular, the effects of global warming. The IPCC Fourth Assessment Report (IPCC 2007, entire) synthesized the projections of the Coupled Model Intercomparison Project (CMIP) Phase 3, a coordinated large set of climate model runs performed at modeling centers worldwide using 22 global climate models (Ray
et al.
2010, p. 11). Based on these projections, the IPCC has concluded that the warming of the climate system is unequivocal, as evidenced from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level (IPCC 2007, pp. 6, 30; Karl
et al.
2009, p. 17). Changes in the global climate system during the 21st century are likely to be larger than those observed during the 20th century (IPCC 2007, p. 19). Several scenarios are virtually certain or very likely to occur in the 21st century including: (1) Over most land, weather will be warmer, with fewer cold days and nights, and more frequent hot days and nights; (2) areas affected by drought will increase; and (3) the frequency of warm spells and heat waves over most land areas will likely increase (IPCC 2007, pp. 13, 53).

In some cases, climate change effects can be demonstrated and evaluated (
e.g.,
McLaughlin
et al.
2002, p. 6073). Where regional effects from global climate change have been demonstrated, we can

rely on that empirical evidence to predict future impacts, such as increased stream temperatures (see status review for Rio Grande cutthroat trout, 73 FR 27900; May 14, 2008) or loss of sea ice (see determination of threatened status for the polar bear, 73 FR 28212; May 15, 2008), and treat these effects as a threat that can be analyzed. In instances for which a direct cause and effect relationship between global climate change and regional effects to a specific species has not been documented, we rely primarily on synthesis documents (
e.g.,
IPCC 2007, entire; Independent Scientific Advisory Board 2007, entire; Karl
et al.
2009, entire) to inform our evaluation of the extent that regional impacts due to climate change may affect our species. These synthesis documents present the consensus view of climate change experts from around the world. Additionally, we have examined models downscaled to specific regions (
e.g.,
Ray
et al.
2010, entire; WRCC 2011, p. 1; CIG 2011, p. 1)—including some in-progress finer-scaled models that include Wyoming and the surrounding area—in order to inform our evaluation of the extent that regional impacts may threaten species. Typically, the projections of downscaled models agree with the projections of the global climate models (Ray
et al.
2010, p. 25). Climate change projections are based on models with assumptions and are not absolute.

Portions of the global climate change models can be used to predict changes at the regional-landscape scale; however, this approach contains higher levels of uncertainty than using global models to examine changes on a larger scale. The uncertainty arises due to various factors related to difficulty in applying data to a smaller scale, and to the paucity of information in these models such as regional weather patterns, local physiographic conditions, life stages of individual species, generation time of species, and species reactions to changing carbon dioxide levels. Additionally, global climate models do not incorporate a variety of plant-related factors that could be informative in determining how climate change could affect plant species (
e.g.,
effect of elevated carbon dioxide on plant water-use efficiency, the physiological effect to the species of exceeding the assumed (modeled) bioclimatic limit, the life stage at which the limit affects the species (seedling versus adult), the life span of the species, and the movement of other organisms into the species' range) (Shafer
et al.
2001, p. 207). Moreover, empirical studies are needed on what determines the distributions of species and species assemblages.

Regional landscapes also can be examined by downscaling global climate models. Two common methods of downscaling are statistical downscaling and dynamic downscaling (Fowler
et al.
2007, p. 1548). These downscaled models typically inherit the broad-scale results of global climate change models, imbed additional information, and run the models at a finer scale (Ray
et al.
2010, p. 25, Hostetler 2011, pers. comm.). These methods provide additional information at a finer spatial scale (
i.e.,
all of Wyoming downscaled to a 15-km (9.3-mi) resolution (Hostetler 2010, pers. comm.). However, they are not able to account for the myriad of processes that may affect a species that only inhabits a narrow range, as local effects may reduce or amplify the large-scale patterns that are projected over the larger spatial resolution of the global climate models (Ray
et al.
2010, p. 24). In summary, global climate models can play an important role in characterizing the types of changes that may occur, so that the potential impacts on natural systems can be assessed (Shafer
et al.
2001, p. 213). However, they are of limited use to assess local impacts to species with a limited range, such as the five plants discussed in this finding.

Climate change is likely to affect the habitat of
Abronia ammophila,
but we lack scientific information on what those changes may ultimately mean for the status of the species
.
Yellowstone Lake water levels affect habitat conditions for
A. ammophila.
As noted previously, the record high lake levels of 1996 and 1997 (due to increased snowpack and subsequent spring snowmelt) had both positive and negative effects on
A. ammophila
(NPS 1999b, p. 7; Whipple 2002, p. 265). In general, the outflow and maximum water surface elevation of Yellowstone Lake are functions of winter snow accumulation and spring precipitation inputs; these vary significantly from year to year (Farnes 2002, p. 73). Analysis of snow depth and last date of snow cover in YNP from 1948 to 2003 has shown that winters are getting shorter, as measured by the number of days with snow on the ground (Wilmers and Getz 2005, entire). This change is due to decreased snowfall and an increase in the number of days with temperatures above freezing (Wilmers and Getz 2005, entire).

Climate change effects are not limited to the timing and amount of precipitation; other factors potentially influenced by climate change may in turn affect the habitat conditions for
Abronia ammophila.
For example, fire frequency, insect populations (
e.g.,
mountain pine beetle,
Dendroctonus ponderosae
), and forest pathogens may be influenced by climate change (Logan and Powell 2001, p. 170; Westerling
et al.
2006, pp. 942-943) and may in turn affect forest canopy cover and the timing of snowmelt within the Yellowstone Lake watershed. The increased rate of snowmelt caused by fire-generated openings in the forest canopy from the 1988 fires in YNP may have slightly reduced the annual maximum Yellowstone Lake level because it spread the snowpack melt rate over a longer period of time (Farnes 2002, p. 73). Impacts of specific events on
A. ammophila
and its habitat have not been analyzed.

Climate change is likely to affect multiple variables that may influence the availability of habitat for
A. ammophila.
As lake levels have fluctuated in the past and
A. ammophila
has adapted to these fluctuations, this species should be able to persist so long as climate change does not result in extreme changes to important characteristics of the species habitat, such as the complete loss of water from Yellowstone Lake. At this time, the best available scientific information does not indicate that impacts from climate change are likely to threaten the species now or in the foreseeable future.

Drought

Precipitation studies show that YNP weather cycles typically follow the larger weather patterns across the larger Northern Rockies ecosystem (Gray
et al.
2007, p. 24). The reconstruction of precipitation levels in YNP from AD 1173-1998 shows strong interannual variability (Gray
et al.
2007, entire). Moreover, extreme wet and dry years, which have occurred recently, fall within the range of past variability (Gray
et al.
2007, entire).

We believe that
Abronia ammophila
has evolved to adapt to recurring drought conditions because it persists in this type of environment. Short-term population fluctuations appear to be typical for the species. The population at Rock Point was thought to have been extirpated due to drought; however, a survey in 2004 located seedlings at this site (Saunders and Sipes 2004, p. 4). The Pumice Point population completely vanishes some years. It is located on sand that does not connect to the aquifer, and during drought years the population can be 9.1 m (30 ft) above water (Whipple 2010e, pers. comm.). Although drought may temporarily influence the abundance of

plants at some specific locations, we have no information indicating that drought threatens the species now or in the foreseeable future.

Summary of Factor A

YNP offers protection of
Abronia ammophila
populations from all kinds of development including roads, campgrounds, buildings, mining, and energy development. There are currently no plans for any further development in YNP near the existing populations or potential habitat of
A. ammophila.
We have no information to suggest that trampling, nonnative invasive plants, climate change, or drought represents a threat to the species.

We conclude that the best scientific and commercial information available indicates that
Abronia ammophila
is not in danger of extinction or likely to become so within the foreseeable future because of the present or threatened destruction, modification, or curtailment of its habitat or range.

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

There has been limited use and collection of
Abronia ammophila
and its parts for scientific study (Saunders and Sipes 2006, p. 77). Additionally, the Denver Botanical Gardens (DBG) collected approximately 3,300
A. ammophila
seeds in 2005 (DBG 2008, p. 3). The DBG is a participating institution in the Center for Plant Conservation, an organization dedicated to preventing the extinction of plants native to the United States (Center for Plant Conservation 2010, unpaginated). Because these collections were limited, we do not believe this collection constituted a threat to the species. The collections also contribute to the long-term conservation of the species.

Specimens, seeds, and parts of
Abronia ammophila
are occasionally collected for scientific purposes in order to increase the knowledge of this species (
e.g.,
Saunders and Sipes 2006; DBG 2008); however, these collections are rare. We do not have any evidence of risks to
A. ammophila
from overutilization for commercial, recreational, scientific, or educational purposes, and we have no reason to believe this factor will become a threat to the species in the future. We conclude that the best scientific and commercial information available indicates that
A. ammophila
is not in danger of extinction or likely to become so within the foreseeable future because of overutilization for commercial, recreational, scientific, or educational purposes.

Factor C. Disease or Predation

Disease

Abronia ammophila
is not known to be affected or threatened by any disease. Therefore, we do not consider disease to be a threat to
A. ammophila
now or in the foreseeable future.

Predation—Grazing and Herbivory

No studies have been conducted investigating the effects of grazing or herbivory on
Abronia ammophila.
Minimal insect herbivory has been noted. Sphingid moth larvae and others tentatively identified in the family
Noctuidae
have been seen feeding on the aboveground plant parts (Saunders and Sipes 2004, p. 11). Also, what appeared to be an army cutworm caterpillar was observed eating the belowground parts of an uprooted plant (NPS 1999b, p. 7).

Additionally, some uprooted, partially eaten taproots were found in areas with abundant rodent tunnels (NPS 1999b, p. 7). Ungulate grazing has been noted on species that grow near
Abronia ammophila;
however, none has been noted on
A. ammophila
(NPS 1999b, p. 7). Any predation, as noted above, would represent a natural ecological interaction in YNP. We have no evidence that the extent of such predation represents a population level threat to
A. ammophila.
Therefore, we do not consider predation to be a threat to the species now or in the foreseeable future.

Summary of Factor C

We have no evidence of adverse impacts to
Abronia ammophila
from disease or predation. We conclude that the best scientific and commercial information available indicates that
A. ammophila
is not in danger of extinction or likely to become so within the foreseeable future because of disease or predation from herbivory or grazing.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

The Act requires us to examine the adequacy of existing regulatory mechanisms with respect to threats that may place
Abronia ammophila
in danger of extinction or likely to become so in the future. Existing regulatory mechanisms that could have an effect on potential threats to
A. ammophila
include (1) local land use laws, processes, and ordinances; (2) State laws and regulations; and (3) Federal laws and regulations.
A. ammophila
occurs entirely on Federal land under the jurisdiction of the YNP; therefore, the discussion below focuses on Federal laws. Actions adopted by local groups, States, or Federal entities that are discretionary, including conservation strategies and guidance, are not regulatory mechanisms; however, we may discuss them in relation to their effects on potential threats to the species.

Federal Laws and Regulations

Yellowstone National Park

All known populations of
Abronia ammophila
occur within YNP. The YNP was established as the first national park on March 1, 1872, under control of the Secretary of the Department of the Interior (NPS 2010c, unpaginated). The NPS was established by the NPS Organic Act of 1916, and reaffirmed by the General Authorities Act, as amended (NPS 2008a, unpaginated; Schneider 2010, pers. comm.). The NPS Organic Act states, “[The NPS] shall promote and regulate the use of the Federal areas known as national parks, monuments, and reservations* * * to conserve the scenery and the natural and historic objects and the wild life therein and to provide for the enjoyment of the same in such manner and by such means as will leave them unimpaired for the enjoyment of future generations” (16 USC 1) (NPS 2006b, p. 8; NPS 2008a, unpaginated; Schneider 2010, pers. comm.).

Additionally, the Management Policies of the NPS state that conservation is paramount in situations of conflict between conserving resources and values and providing for enjoyment of them (NPS 2006b, p. 9; Schneider 2010, pers. comm.). These policies also charge the NPS with preserving the fundamental physical and biological processes, and maintaining all the components and processes of a naturally evolving park ecosystem, including the natural abundance, diversity, and genetic and ecological integrity of the plant and animal species native to those ecosystems (NPS 2006b, pp. 35-36; Schneider 2010, pers. comm.). The NPS is responsible for the inventory of native species that are of special management concern to parks (such as rare, declining, sensitive, or unique species and their habitats) and will manage them to maintain their natural distribution and abundance (NPS 2006b, pp. 45-46; Schneider 2010, pers. comm.). The Management Policies also direct the NPS to control detrimental nonnative species and manage detrimental visitor access (NPS 2006, p. 45).

As stated above, YNP is required, to the maximum extent practicable, to

prevent exotic (nonnative invasive) plant introduction and to control established exotic plants by law, executive order, and management policy (
e.g.,
Executive Order 13112, National Park Service Management Policies (NPS 1988), and the Federal Noxious Weed Act of 1974) (Olliff
et al.
2001, pp. 348-349). YNP's approach emphasizes prevention, education, early detection and eradication, control, and monitoring (Olliff
et al.
2001, entire).

Visitors to national parks are prohibited from removing, defacing, or destroying any plant, animal, or mineral; this includes collecting natural or archeological objects (NPS 2006c, p. 2). Visitors are prohibited from driving off roadways or camping outside of designated campgrounds (NPS 2010d, unpaginated). Additionally, YNP has developed a Conservation Plan for
Abronia ammophila
(NPS 1999b, entire). This plan recommends the protection of all known (and any newly discovered) populations, monitoring of the populations, reestablishment of historical occupancy areas, long-term seed storage, and research (NPS 1999b, pp. 10-11).

National Environmental Policy Act

All Federal agencies are required to adhere to the National Environmental Policy Act (NEPA) of 1970 (42 U.S.C. 4321
et seq.
) for projects they fund, authorize, or carry out. The Council on Environmental Quality's regulations for implementing NEPA (40 CFR 1500-1518) state that agencies shall include a discussion on the environmental impacts of the various project alternatives, any adverse environmental effects which cannot be avoided, and any irreversible or irretrievable commitments of resources involved (40 CFR 1502). Additionally, activities on non-Federal lands are subject to NEPA if there is a Federal nexus. The NEPA is a disclosure law, and does not require subsequent minimization or mitigation measures by the Federal agency involved. Although Federal agencies may include conservation measures for sensitive species as a result of the NEPA process, any such measures are typically voluntary in nature and are not required by the statute.

Summary of Factor D

We considered the adequacy of existing regulatory mechanisms to protect
Abronia ammophila.
We believe the existing regulatory mechanisms, especially the NPS Organic Act, adequately protect the Yellowstone Lake shore habitat of
Abronia ammophila
from the potential threats of development, trampling, and nonnative invasive plants. We expect that
A. ammophila
and its habitat will be generally protected from direct human disturbance. Therefore, we conclude that the existing regulatory mechanisms are adequate to protect
A. ammophila
from the known potential threat factors.

We conclude that the best scientific and commercial information available indicates that
Abronia ammophila
is not in danger of extinction or likely to become so within the foreseeable future because of inadequate regulatory mechanisms.

Factor E. Other Natural or Manmade Factors Affecting Its Continued Existence

Natural and manmade factors with the potential to affect
Abronia ammophila
include: (1) Small population size, (2) pollination, and (3) genetic diversity.

Small Population Size

Small populations can be especially vulnerable to environmental disturbances such as habitat loss, nonnative species, grazing, and climate change (Barrett and Kohn 1991, p. 7; Oostermeijer 2003, p. 21; O'Grady 2004, pp. 513-514). However, plants that are historically rare may have certain adaptations to rarity (
e.g.,
early blooming, extended flowering, or mixed-mating systems) that enable them to persist (Brigham 2003, p. 61).

Based on herbarium records, extirpation of
Abronia ammophila
sites has occurred (see Distribution and Abundance discussion above). However, additional sites also have been recently discovered, and not all suitable habitat within YNP has been surveyed (NPS 1999a, pp. 6-7). We have no information on whether these new sites represent recent expansion of the species or if surveys were not previously conducted in these areas.

We do not have any indication that
Abronia ammophila
was ever present on the landscape over a more extensive range. Existing sites are monitored, and surveys have located new occurrences. We have no information indicating that random demographic or environmental events are a threat to the species now or in the foreseeable future because of its small population size.

Pollination

Small populations may represent an unreliable food source, which may be visited by fewer pollinators than larger, less fragmented populations (Oostermeijer 2003, p. 23). However, low visitation rates may be more of a concern in currently rare species that were historically abundant (Brigham 2003, p. 84). We have no information suggesting that
Abronia ammophila
was previously more abundant across the landscape. Co-flowering species (species that flower during the same timeframe) also may be important to pollination of
A. ammophila;
the pollinators recorded as visiting
A. ammophila
also were observed visiting other dune plants in the vicinity (Saunders and Sipes 2004, p. 13).

Only very limited information is available regarding pollination of
Abronia ammophila.
However,
A. ammophila
is a historically rare species that exhibits a mixed-mating system. A mixed-mating system and co-flowering species may help alleviate negative effects that may occur due to low pollination visitation rates. Therefore, we have no information indicating that poor pollination is a threat to the species now or in the foreseeable future.

Genetic Diversity

Small population size can decrease genetic diversity due to genetic drift (the random change in genetic variation each generation), and inbreeding (mating of related individuals) (Antonovics 1976, p. 238; Ellstram and Elam 1993, pp. 218-219). Genetic drift can decrease genetic variation within a population by favoring certain characteristics and, thereby, increasing differences between populations (Ellstram and Elam 1993, pp. 218-219). Self-fertilization and low dispersal rates can cause low genetic diversity due to inbreeding (Antonovics 1976, p. 238; Barrett and Kohn 1991, p. 21). This decreased genetic diversity diminishes a species' ability to adapt to the selective pressures of a changing environment (Newman and Pilson 1997, p. 360; Ellstrand 1992, p. 77).

Limited information is available regarding the genetic diversity of the
Abronia
genus. No information is available regarding the genetic diversity exhibited by
Abronia ammophila.
Therefore, we have no information indicating that a lack of genetic diversity is a threat to the species now or in the foreseeable future.

Summary of Factor E

Abronia ammophila
is a historically rare species that, as such, has adaptations such as a mixed-mating system and prolific flowering, which minimize the risks of small population size, low pollinator abundance, and genetic diversity. Therefore, we conclude that the best scientific and commercial information available indicates that
Abronia ammophila
is not in danger of extinction or likely to become so within the foreseeable future because of small population size,

pollination, or reduced genetic diversity.

Finding for
Abronia ammophila

As required by the Act, we considered the five factors in assessing whether
Abronia ammophila
is threatened or endangered throughout all of its range. We examined the best scientific and commercial information available regarding the past, present, and future threats faced by
A. ammophila.
We reviewed the petition, information available in our files, other available published and unpublished information, and we consulted with recognized
A. ammophila
experts and other Federal and State agencies.

The primary factor potentially impacting
Abronia ammophila
is human disturbance through trampling. However, studies that have sought to quantify foot traffic in the habitat of
A. ammophila
have found that there is little foot traffic occurring (NPS 1999a, pp. 2, 5). Additionally,
A. ammophila
prefers open sites and thrives under some disturbance. Other factors potentially affecting
A. ammophila
—including nonnative invasive plants, drought, small population size, limited pollinators, and genetic diversity—are either limited in scope, or lacking evidence apparent to us indicating that they adversely impact the species. We have no evidence that overutilization, disease, or predation are affecting this species. Although climate change will likely impact the status of some plant species in the future, we do not have enough information to determine that climate change will result in a species-level response from
A. ammophila.
Additionally, the existing regulatory mechanisms directing management of YNP appear to be adequate to protect the species from potential threats.

Based on our review of the best available scientific and commercial information pertaining to the five factors, we find that the threats are not of sufficient imminence, intensity, or magnitude to indicate that
Abronia ammophila
is in danger of extinction (endangered) or likely to become endangered within the foreseeable future (threatened), throughout all of its range. Therefore, we find that listing
A. ammophila
as a threatened or endangered species is not warranted throughout its range.

Significant Portion of the Range

Having determined that
Abronia ammophila
does not meet the definition of a threatened or endangered species, we must next consider whether there are any significant portions of the range where
A. ammophila
is in danger of extinction or is likely to become endangered in the foreseeable future.

In determining whether
Abronia ammophila
is threatened or endangered in a significant portion of its range, we first addressed whether any portions of the range of
A. ammophila
warrant further consideration. We evaluated the current range of
A. ammophila
to determine if there is any apparent geographic concentration of the primary stressors potentially affecting the species including trampling, nonnative invasive plants, drought, small population size, limited pollinators, and genetic diversity. This species' small range suggests that stressors are likely to affect it in a uniform manner throughout its range. However, we found the stressors are not of sufficient imminence, intensity, magnitude, or geographically concentrated such that it warrants evaluating whether a portion of the range is significant under the Act. We do not find that
A. ammophila
is in danger of extinction now, nor is likely to become endangered within the foreseeable future, throughout all or a significant portion of its range. Therefore, listing
A. ammophila
as threatened or endangered under the Act is not warranted at this time.

We request that you submit any new information concerning the status of, or threats to,
Abronia ammophila
to our Wyoming Ecological Services Field Office (see
ADDRESSES
section) whenever it becomes available. New information will help us monitor
A. ammophila
and encourage its conservation. If an emergency situation develops for
A. ammophila,
or any other species, we will act to provide immediate protection.

Species Information for
Agrostis rossiae

Species Description

Agrostis rossiae
is a small annual grass in the family Poaceae (Clark
et al.
1989, p. 8; Fertig 1994, unpaginated; 2000c, unpaginated).
A. rossiae
grows as a dense clump about 5 to 15 cm (2.0 to 5.9 in.) high (Fertig 2000c, unpaginated). The short leaves are 1.0 to 2.5 cm (0.39 to 0.98 in.) long, and 0.5 to 2.0 millimeters (mm) (0.02 to 0.08 in.) wide, with slightly inflated and smooth sheaths (the lower part of the leaf that surrounds the stem) (Clark
et al.
1989, p. 8; Clark and Dorn 1981, p. 10; Fertig 1994, unpaginated; 2000c, unpaginated). The one-flowered spikelets (flowers) form at the top of the stems in a narrow, compact panicle (a structure in which the flowers mature from the bottom upwards) that is 2.0 to 6.0 cm (0.79 to 2.36 in.) long (Dorn 1980, p. 59; Fertig 2000c, unpaginated). The panicle remains compact at maturity (Fertig 1994, unpaginated). Branches of the panicle are scabrous (rough), purple, and lack spikelets at the base (Clark
et al.
1989, p. 8; Dorn 1980, p. 59; Fertig 2000c, unpaginated).

Discovery and Taxonomy

Edith A. Ross collected the first recorded specimen of
Agrostis rossiae
in July of 1890 (Vasey 1982, p. 77; Hitchcock 1905, p. 41). The genus
Agrostis
consists of over 100 species occurring in both hemispheres, typically in cooler areas of temperate climates (Hitchcock 1905, p. 5). More recent sources list 150 to 200 species (Harvey 2007, unpaginated), or up to 220 species within the
Agrostis
genus

(Watson and Dallwitz 1992, unpaginated).

Species of the
Agrostis
genus are able to form morphologically similar ecotypes (subspecies that survives as a distinct group due to environmental pressures and isolation) in response to variations in climate, heavy metals in the soil, and other unusual soil conditions (Bradshaw 1959, entire; Jowett 1964, p. 78; Aston and Bradshaw 1966, entire; Jain and Bradshaw 1966, pp. 415-417). Therefore, morphology of
Agrostis
species is not a reliable indicator of species (Tercek 2003, p. 9).

In the geothermally influenced areas of YNP, thermal
Agrostis scabra
(rough bentgrass) is sympatric (occurs in the same area) with
Agrostis rossiae
(Tercek 2003, pp. 9-10).
A. scabra
occurs as an annual in the thermal areas of YNP; however, this species is typically a perennial when it occurs in nonthermal habitats (Fertig 2000c, unpaginated; Tercek 2003, pp. 9-10).
A. scabra
can be distinguished from
A. rossiae,
when mature, by its spreading panicle (Fertig 1994, unpaginated; 2000c, unpaginated; Tercek 2003, pp. 9-10). Another similar species, although not sympatric, is
Agrostis variabilis
(mountain bentgrass), which is a perennial with panicle branches bearing spikelets nearly to the base (whereas
A. rossiae
lacks spikelets at the base) (Fertig 1994, unpaginated; Fertig 2000c, unpaginated). Genetic studies have shown that thermal
Agrostis
species occurring in YNP are more closely related to other thermal
Agrostis
species worldwide than to the nonthermal
Agrostis scabra
(Tercek 2003, pp. 17-21). Additionally,
A. rossiae
and thermal
A. scabra
are closely related to each other (Tercek
et al.
2003, p. 1308-1309); however, additional genetic studies need to be completed to quantify their relationship. We recognize
A. rossiae
as a valid species and a listable entity.

Biology and Life History

Agrostis rossiae
is a thermal species that takes advantage of the warmth from its environment and germinates from December to January, when nonthermal areas remain covered in snow (Tercek 2003, pp. 12, 45, 51). The growing season for
A. rossiae
is from December 1 to April 1; it blooms in May, matures in June, and dies by mid-June when the thermal ground temperature reaches between 40 and 45 °C (104 and 113 °F) (a temperature that kills
A. rossiae
) (Beetle 1977, p. 40; Tercek 2003, pp. 10, 34, 12, 45, 51-52).

Agrostis rossiae
plants do not have a reduced seed set when isolated from external pollen sources; this suggests that
A. rossiae
reproduces through apomixis (reproduction that does not involve pollination) (Tercek 2003, p. 19). Seeds remain viable for about 100 years in artificial conditions, but persist for less time in natural conditions (Tercek 2010, pers. comm.). Seeds do not disperse very far from the parent plant (Whipple 2010a, pers. comm.).

Habitat

Typically,
Agrostis rossiae
grows on glacial deposits, which are at a slightly higher elevation than nearby hot springs (Tercek 2003, p. 11). These deposits border active geysers and hot springs at elevations of 2,210 to 2,256 m (7,250 to 7,400 ft) (Clark
et al.
1989, p. 8; Fertig 1994, unpaginated; 2000c, unpaginated). These geothermally influenced soils remain moist throughout the year even though they are partially isolated from the water table of nearby hot springs by the higher elevation or a nonpermeable rock layer (White
et al.
1971, p. 77; Fournier 1989, pp. 20-21; Tercek 2003, pp. 36, 45-46; Tercek and Whitbeck 2004, p. 1956).

The geysers in YNP are vapor-dominated, meaning that steam and other gases rise out of the ground (Fournier 1989, pp. 20-21; Tercek 2003, p. 36). The geysers are important to the soils because the elements and chemicals produced from the geysers affect the composition of the soil on which this species grows. The accompanying soils are rich in silica and calcium, and contain gases such as hydrogen sulfide and iron sulfide that are converted into sulfuric acid by bacteria (Tercek and Whitbeck 2004, p. 1956; White
et al.
1971, p. 77; Fournier 1989, pp. 20-21; Tercek 2003, p. 36). The sulfuric acid lowers the pH (a measure of acidity and alkalinity) of the soil (White
et al.
1971, p. 77; Fournier 1989, pp. 20-21; Tercek 2003, p. 36). YNP's thermal soils are more acidic (pH 3.9-5.6), in general, than the nonthermal soils (pH 4.3-6.4) (Tercek and Whitbeck 2004, p. 1964).
Agrostis rossiae
demonstrates peak growth in acidic soils (pH 3.0), whereas the optimal growth of both thermal and nonthermal
Agrostis scabra
occurs at a pH of 5.0 (Terceck and Whitbeck 2004, p. 1964). While
A. rossiae
is more tolerant of acidity than other sympatric
Agrostis
species, its growth declines at pH of less than 3.0 (Tercek and Whitbeck 2004, p. 1964). Many of the thermal features in YNP have a very high acidity (Whipple 2011, pers. comm.).

In addition to
Agrostis scabra,
a limited number of thermally adapted species occur in the same habitat as
Agrostis rossiae: Racomitrium canescens
(Racomitrium moss),

several heat-loving soil fungi, a heat-tolerant grass—
Dichanthelium lanuginosum
(panicgrass), and a few annual forbs (Tercek and Whitbeck 2004, p. 1956). Annual forbs include
Conyza canadensis
(Canadian horseweed),
Gnaphalium stramineum
(cottonbatting plant),
Plantago elongata
(Prairie plantain),
Mimulus guttatus
(seep monkeyflower), and
Heterotheca depressa
(hairy false goldenaster) (Fertig 2000c, unpaginated).

Distribution and Abundance

Agrostis rossiae
is endemic to YNP, occurring only in Teton County, Wyoming (Beetle 1977, p. 40; Clark and Dorn 1981, p. 10; Clark
et al.
1989, p. 8; Fertig 2000c, unpaginated, Tercek 2003, p. 10). Even though there are many thermal areas in YNP,
Agrostis rossiae
only occurs in the west-central portion of YNP (Tercek 2003, p. 10). Specifically,
A. rossiae
only occurs in the Firehole River drainage and the Shoshone Geyser Basin (Greater Yellowstone 2010, unpaginated). The reason for this restriction is not known. One proposed hypothesis is that the high acidity of some of the other thermal areas restricts the species' distribution; another is that
A. rossiae
is a fairly recently evolved species that has not had time for successive generations to disperse and colonize a wider area (Whipple 2010e, pers. comm.).

Four known populations of the plant occur in an area of approximately 4.86 ha (12 ac); these populations are named Upper Geyser Basin, Shoshone, Midway, and Lower Geyser (Whipple 2010a, pers. comm.). Many of these occurrences are ephemeral (only persist for a short period) subpopulations (Fertig 2000c, unpaginated). Because of the changing thermal habitat, subpopulation numbers and locations may fluctuate greatly (Fertig 2000c, unpaginated). One small (generally less than 50 plants) subpopulation northeast of Infant Geyser in Geyser Hill disappeared due to changes in soil temperatures between 1992 and 2008 (Fertig 2000c, unpaginated; Whipple 2010e, pers. comm.).

The WNDD has designated
Agrostis rossiae
as a plant species of concern with ranks of G1 and S1 (Heidel 2007, p. 1). This designation indicates that
A. rossiae
is considered to be critically imperiled because of extreme rarity. For background information on G1 and S1 rankings, please refer to the last paragraph under
Distribution and Abundance
in the Species Information for
Abronia ammophila
section.

Since
A. rossiae
is endemic to Wyoming, the Wyoming occurrences encompass the entire global range. Additionally, YNP considers
A. rossiae
to be a sensitive species of concern; therefore, it evaluates effects to this species in conjunction with any project or action that has the potential to affect the plant (Whipple 2011, pers. comm.).

Trends

Subpopulations can range in size from a solitary plant up to several thousand plants, in an area with a diameter of 100 m (328.1 ft) (Tercek 2003, p. 10; Tercek and Whitbeck 2004, p. 1956). Surveys conducted in 1995 suggest that the total population of all known
Agrostis rossiae
plants is approximately 5,000 to 7,500 individuals (Fertig 2000a, p. 36; 2000a, unpaginated). The 1998 survey determined the total population consisted of between 5,580 and 7,735 plants (Whipple
in litt.
2009, entire). The entire population has not been surveyed in any additional years (Whipple
in litt.
2009, entire). Surveys have been completed on a sporadic schedule, with not all populations surveyed in a given year (Whipple 2009
in litt.,
unpaginated). All population counts are estimates as
A. rossiae
is an annual with a clumped growth form, and exact counts are unable to be obtained without destroying the plants (Whipple 2010d, pers. comm.). Overall, there is not enough information to conclusively determine rangewide trends; however, the total population numbers appear to be stable despite subpopulation fluctuations. Additionally, the known populations have expanded in the last 3 years (Whipple 2010a, pers. comm.).

Five Factor Evaluation for
Agrostis rossiae

Information pertaining to
Agrostis rossiae
in relation to the five factors provided in section 4(a)(1) of the Act is discussed below.

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
Agrostis rossiae
are discussed in this section, including: (1) Development, (2) trampling, (3) nonnative invasive species, (4) climate change, (5) thermal fluctuations, (6) drought, and (7) fire.

Development

Agrostis rossiae
occurs entirely inside YNP, which limits potential threats to its habitat from development. As stated above (see Factor D under
Abronia ammophila
), YNP owns both its land and the mineral rights so energy development within the YNP's boundary is not a threat (Mazzu 2010, pers. comm.; Whipple 2010e, pers. comm.).

In the late 1970s and early 1980s, potential for geothermal energy development outside YNP was considered a threat to
Agrostis rossiae
because of the potential to affect the thermal basin that underlies YNP (Fertig 2000, unpaginated). Currently, no known applications for geothermal leases have this potential (Mazzu 2010, pers. comm.; Whipple 2010e, pers. comm.). However, applications are occasionally made for geothermal leases in the geothermal areas outside of YNP (NPS 2008b, unpaginated). The Geothermal Steam Act of 1970 (30 U.S.C. 1001-1027, December 24, 1970), as amended in 1977, 1988, and 1993, provides protections for the thermal features in YNP (see
Factor D. The Inadequacy of Existing Regulatory Mechanisms
below) (Legal Information Institute 2010, unpaginated). This law should protect the species, unless high energy costs, such as occurred in the late 1970s and early 1980s, encourage development interest that results in changes that weaken these protections. Therefore,
A. rossiae
is not threatened by geothermal energy development inside or outside of YNP's boundary.

As stated above, new construction of roads, trails, or structures occurring in YNP is rare, with reconstruction of existing features occurring occasionally (Whipple 2010e, pers. comm.). When new construction or reconstruction occurs in areas where there are sensitive species, YNP analyzes and carries out construction in a manner that minimizes adverse effects. For example, the reconstruction of the Biscuit Basin Boardwalk in the summer of 2010 included rerouting the boardwalk and restoration of
Agrostis rossiae
habitat that had been impacted during prior maintenance (Whipple 2010a, pers. comm.; 2010e, pers. comm.).

The majority of YNP remains undeveloped, and we have no information that this will change; therefore, we do not view development to be a threat to the species now or in the foreseeable future.

Trampling

Most habitat of
Agrostis rossiae
is easily accessible to visitors, as it is generally located near popular thermal features in YNP (Whipple 2010a, pers. comm.). However, visitors are required to stay on boardwalks and designated trails around thermal areas (NPS 2006c, unpaginated). Human impact to
A. rossiae
was noted in a survey of the Shoshone Geyser Basin area (Whipple 2009
in litt.,
unpaginated). This trampling was partially mitigated by the reroute discussed above; surveys in 2000, after the trail was rerouted, documented a healthy
A. rossiae
population (Whipple 2009
in litt.,
unpaginated). No studies have specifically examined disturbance due to trampling or its effects on
A. rossiae.
However,
A. rossiae
is typically located in the vicinity of thermal features that could be detrimental for humans to walk near, and any areas that have the potential for trampling are protected by YNP's policies.

For information on impacts of increased visitation to YNP, please refer to the “Trampling” discussion under
Factor A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range
in the Five Factor Evaluation for
Abronia ammophila
section. As the plant is located in YNP, it is afforded protections (see
Factor D: The Inadequacy of Existing Regulatory Mechanisms
below).

Wildlife, also, have the potential to trample
Agrostis rossiae.
American bison (
Bison bison
) scat (fecal droppings) has been found in the vicinity of
A. rossiae
at several sites; however, no trampling of
A. rossiae
was noted in the survey notes (Whipple 2009
in litt.,
unpaginated). In 1998, a small patch of
A. rossiae
was highly impacted by the actions of a rutting bull elk (
Cervus canadensis
); however, that
A. rossiae
population was reported to be healthy when resurveyed in 2000 (Whipple 2009
in litt.,
unpaginated). We believe that these anecdotal observations do not add up to routine impacts on a scale that would cause the species to be threatened or endangered. Additionally, we believe that trampling by wildlife, as noted above, represents a natural ecological interaction in YNP with which the species would have evolved and poses no threat to long-term persistence.

We have no information indicating that trampling by either humans or wildlife is a threat to the species now or in the foreseeable future.

Nonnative Invasive Plants

For general background information on nonnative invasive plants, please refer to the first paragraph of “Nonnative Invasive Plants” under
Factor A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range
in the Five Factor Evaluation for
Abronia ammophila
section
.

As stated above,

as of 2010, YNP has documented 218 nonnative plant species occurring within its boundaries (NPS 2010e, p. 1). The majority of these plants have not been documented in or around
Agrostis rossiae
habitat. Encroachment of nonnative species has the potential to affect
Agrostis rossiae.
However, at this time, none of the nonnative species are able to tolerate the hottest of the thermal habitats, where
A. rossiae
primarily grows (Whipple 2010e, pers. comm.). Several nonnative species that are considered either invasive or exotic occur near the thermal habitats of
A. rossiae
(Whipple 2009
in litt.,
entire). In order to combat nonnative invasives that can tolerate the transition areas closer to the thermal habitat of
A. rossiae,
YNP is targeting
Rumex acetosella
(common sheep sorrel) around the Shoshone Geyser Basin (Schneider 2010 pers. comm.) and
Hypericum perforatum
(St. John's wort) near the Lower Geyser Basin (Whipple 2010f, pers. comm.). Additionally, NPS plans to establish trial plots in some of the geyser basins to determine the best control mechanisms (Schneider 2010 pers. comm.). Nonnative species currently occur only within the transition zones and not in the hot thermal habitat of
A. rossiae.
Additionally, the NPS has an exotic plant management plan (see
Factor D: The Inadequacy of Existing Regulatory Mechanisms
in the Five Factor Evaluation for
Abronia ammophila
section), which includes measures to identify and treat any new nonnatives; therefore, we believe that
A. rossiae
will be protected from nonnative plant invasions.

We have no information indicating that nonnative invasive species are modifying the habitat of
Agrostis rossiae
to the extent that they represent a threat to the species now or in the foreseeable future.

Climate Change

For general background information on climate change, please refer to the first paragraphs of “Climate Change” under
Factor A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range
in the Five Factor Evaluation for
Abronia ammophila
section.

Agrostis rossiae
is adapted to an ephemeral habitat subject to lethal summer soil temperatures and appears most clearly influenced by the condition of thermal features as opposed to other climatic factors. Although climate change has the potential to affect the species' habitat, it is not clear that climate change has relevance to the condition or availability of habitat for this species because we have no information that climate change will play a significant role in altering geothermal features. Climate change may affect the timing and amount of precipitation as well as other factors linked to habitat conditions for this species. We are uncertain how these changes will affect the geothermal habitat of
A. rossiae.
At this time the available scientific information does not clearly indicate that climate change is likely to threaten the species now or in the foreseeable future.

Thermal Fluctuations

The thermal features in YNP are part of the largest and most varied geyser basin in the world; this basin is essentially undisturbed (NPS 2008b, unpaginated). Few of YNP's thermal features have ever been diverted for human use (such as bathing pools or energy), despite the proximity of roads and trails (NPS 2008b, unpaginated). Thermal features can be affected by nearby ground-disturbing activities; water, sewer, and other utility systems adjacent to YNP have likely affected the park's features in the past (NPS 2008b, unpaginated). In other countries, geothermal drill holes and wells located 4.02 to 9.98 km (2.5 to 6.2 mi) from thermal features have reduced geyser activity and hot spring discharges (NPS 2008b, unpaginated). Connections between YNP's underlying geothermal basins are not fully understood. Therefore, if geothermal activities were to occur outside YNP, they could have the potential to affect this species.

Agrostis rossiae
tends to follow very subtle geothermal features, growing along geothermal cracks and edges of sunken pools (Whipple 2010e, pers. comm.). For example, in Cathos Springs,
A. rossiae
currently grows along one crack and in a ring around the spring; however, when the water level is higher or the ground level hotter, the distribution shifts, or the plant may not be present at all in a given year (Whipple 2010e, pers. comm.). As discussed above, the Geothermal Steam Act of 1970 (30 U.S.C. 1001-1027, December 24, 1970), as amended in 1977, 1988, and 1993, prevents significant adverse effects to the thermal features in YNP (see
Factor D: The Inadequacy of Existing Regulatory Mechanisms
below) (Legal Information Institute 2010, unpaginated). Additionally, the NPS is included in discussions of activities that may affect the groundwater or geothermal areas of YNP (Mazzu 2010, unpaginated). Therefore, we have no information indicating that human-caused changes to the thermal features are likely to threaten the species now or in the foreseeable future.

Drought

For background information, please refer to the first paragraph of the “Drought” discussion under
Factor A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range
in the Five Factor Evaluation for
Abronia ammophila
section. As noted above under the
Habitat
section for this species, the vapor-dominated geothermally influenced soils on which
Agrostis rossiae
typically grows remain moist throughout the year (Tercek 2003, pp. 36, 45-46). However, these soils are influenced by the amount and timing of the rain that falls in the area (Tercek and Whitbeck 2004, p. 1958). Typically around May or June, the snow in the surrounding area has melted and rains are no longer frequent enough for the soils in the areas surrounding the habitat of
A. rossiae
to remain moist (Tercek and Whitbeck 2004, p. 1958). This decrease in soil moisture of the surrounding habitat is accompanied by a sharp increase in the thermal soil temperatures (Tercek and Whitbeck 2004, p. 1958). The typical growing season in the hot thermal habitats is approximately 120 days (Tercek and Whitbeck 2004, p. 1963).
A. rossiae
requires only 30 to 70 days to complete its life cycle (Tercek and Whitbeck 2004, p. 1963). A decrease in the growing season of 40 percent could occur prior to drought having a detrimental effect on this species. Prediction models indicate that areas already affected by drought will suffer greater effects from temperature increases caused by climate change and that high precipitation effects will become more frequent (IPCC 2007, entire). Although we do not fully understand how these changes will affect the habitat of
A. rossiae,
we do know that this species is resilient to changes in the thermal basins of its environment. Therefore, we do not believe that drought will rise to the level of a threat to the species now or in the foreseeable future.

Fire

As
Agrostis rossiae
completes its annual life cycle by mid-June, it is typically dead by the time fire season occurs (Whipple 2010e, pers. comm.); YNP's fire season generally extends from late June to the first large rain events in September. The fires in 1988 burned the area where
A. rossiae
occurs; however, the fire did not carry on the ground through the
A. rossiae
populations and, therefore, did not have any effect on the population (Whipple 2010e, pers. comm.). We have no information indicating that fire is likely to threaten the species now or in the foreseeable future.

Summary of Factor A

YNP offers protection to the populations of
Agrostis rossiae
from all kinds of development, including roads, campgrounds, buildings, mining, and energy development. There are currently no plans for any further development in YNP near the existing populations or potential habitat of
A. rossiae.
We have no information to show that
Agrostis rossiae
is likely to be threatened by trampling, nonnative species, climate change, thermal fluctuations, drought, or fire.

We conclude that the best scientific and commercial information available indicates that
Agrostis rossiae
is not in danger of extinction or likely to become so within the foreseeable future because of the present or threatened destruction, modification, or curtailment of its habitat or range.

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

There has been limited use and collection of the leaves of
Agrostis rossiae
for scientific purposes to determine the genetic relationship between different
Agrostis
species (Tercek 2003, p. 12). We have no indications of
A. rossiae
being collected for any other purposes (Whipple 2010e, pers. comm.). Therefore, we conclude that the best scientific and commercial information available indicates that
A. rossiae
is not in danger of extinction or likely to become so within the foreseeable future because of overutilization for commercial, recreational, scientific, or educational purposes.

Factor C. Disease or Predation

Agrostis rossiae
is not known to be affected or threatened by any disease. We have no records showing predation by grazing or herbivory on
A. rossiae.
Therefore, we conclude that the best scientific and commercial information available indicates that
A. rossiae
is not in danger of extinction or likely to become so within the foreseeable future because of disease or predation.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

All known populations of
Agrostis rossiae
occur within YNP, which is under the jurisdiction of the NPS. Please refer to
Yellowstone National Park
under the
Factor D: The Inadequacy of Existing Regulatory Mechanisms
section in the Five Factor Evaluation for
Abronia ammophila
section for additional information.

The Geothermal Steam Act of 1970 (30 U.S.C. 1001-1027, December 24, 1970), as amended in 1977, 1988, and 1993, governs the lease of geothermal resources on public lands (Legal Information Institute 2010, unpaginated). In addition to preventing the issuance of geothermal leases on lands in YNP, it prevents the issuance of any lease that is reasonably likely to result in a significant adverse effect on thermal features within YNP (Legal Information Institute 2010, unpaginated).

Summary of Factor D

The existing regulatory mechanisms, especially the NPS Organic Act and the Geothermal Steam Act, appear to adequately protect
Agrostis rossiae
and its habitat in YNP. We expect that
A. rossiae
and its habitat will be generally protected from direct human disturbance. Therefore, we conclude that the existing regulatory mechanisms are adequate to protect
A. rossiae
from the known potential threat factors.

We conclude that the best scientific and commercial information available indicates that
Agrostis rossiae
is not in danger of extinction or likely to become so within the foreseeable future because of the inadequacy of existing regulatory mechanisms, provided the existing mechanisms are not weakened or removed.

Factor E. Other Natural or Manmade Factors Affecting Its Continued Existence

Natural and manmade factors with the potential to affect
Agrostis rossiae
include: (1) Competition and hybridization, (2) small population size, and (3) genetic diversity.

Competition and Hybridization

Previously,
Agrostis scabra
has been listed as a threat to
Agrostis rossiae,
possibly because of competition or hybridization

(
e.g.,
Fertig 2000a; 2000c; NatureServe 2010a, p. 1). However,
A. scabra
is a native species that does not compete with or restrict
A. rossiae
(Whipple 2010a, pers. comm.). The thermal areas in which
A. rossiae
grows have lethal summer soil temperatures (greater than 45 °C (113 °F)) that preclude the growth of perennial roots and reproduction of any plant that requires greater than 120 days to complete its life cycle (Tercek 2003, p. 51). Nonthermal
A. scabra
is able to germinate in garden experiments of thermal temperatures; however, nonthermal
A. scabra
seldom occurs in the interior of the thermal habitats where
A. rossiae
occurs (Tercek 2003, p. 53). Additionally, nonthermal
A. scabra
requires a growing season of approximately 160 days in order to flower; the typical growing season in the transition zone between thermal and nonthermal ground is approximately 105 days (Tercek 2003, p. 52). Therefore, even if the nonthermal
A. scabra
germinated in the transition zone, it would be unable to reproduce before desiccation occurred.

Conversely, thermal
Agrostis scabra
is able to flower at the same time as
Agrostis rossiae
(Tercek 2003, p. 10). However, each thermal area is typically populated by only one of these species because of differences in microhabitat requirements (
e.g.,
soil temperature, soil pH) (Tercek 2003, p. 10). A few thermal areas do support populations of both
A. rossiae
and thermal
A. scabra
(Whipple 2010e, pers. comm.); however,
A. rossiae
and thermal
A. scabra
maintain separate morphologies in these locations and when they are grown under uniform laboratory conditions (Tercek
et al.
2003, p. 1311; Whipple 2010e, pers. comm.).

Additionally, attempts to cross-pollinate
A. rossiae
and thermal
A. scabra
were unsuccessful; however, experiments that are more rigorous are needed to determine conclusively whether these two
Agrostis
species can hybridize (Tercek 2003, p. 19) and to confirm that there is not a crossbreeding effect that could be a threat to
A. rossiae.

Small Population Size

For general background information on small population size, please refer to the first paragraph of “Small Population Size” under
Factor E. Other Natural or Manmade Factors Affecting Its Continued Existence
in the Five Factor Evaluation for
Abronia ammophila
section.

We do not have any indication that
Agrostis rossiae
was ever present on the landscape over a more extensive range. Nor do we have any evidence that the populations of
A. rossiae
are sufficiently small to experience the problems that occur in some species because of small population size. Additionally,
A. rossiae
has the potential to expand its habitat, although potential habitat may be limited (see Distribution and Abundance) (Whipple 2010e, pers. comm.). We have no information indicating that random demographic or environmental events are a threat to the species because of a small population size. Therefore, we do not consider small population size to be a threat to
A. rossiae
now or in the foreseeable future.

Genetic Diversity

For general background information on genetic diversity, please refer to the first paragraph of “Genetic Diversity” under
Factor E. Other Natural or Manmade Factors Affecting Its Continued Existence
in the Five Factor Evaluation for
Abronia ammophila
section.

Decreased genetic diversity diminishes a species' ability to adapt to the selective pressures of a changing environment (Newman and Pilson 1997, p. 360; Ellstrand 1992, p. 77). However,
Agrostis rossiae
continually adapts to the changing thermal conditions of its environment and is able to shift its distribution to follow these changes (Whipple 2010e, pers. comm.). Therefore, potential decreased genetic diversity does not appear to be affecting
A. rossiae.

Gene flow can also have negative effects on a species (Ellstrand 1992, p. 77). Genes favoring adaptations to a different environment or hybridization between two species can result (Ellstrand 1992, p. 77). Gene flow between
Agrostis
populations is low (Tercek 2003, p. 19). Therefore, there may be some risk to the species, but we do not fully understand this risk based on currently available information.

Limited information is available about the genetic diversity of
Agrostis rossiae.
We do not have any indication that
A. rossiae
is at risk of suffering from reduced genetic diversity and consider it capable of adapting to changes based on our current understanding of the species' genetics. Therefore, we do not consider reduced genetic diversity to be a threat to
A. rossiae
now or in the foreseeable future.

Summary of Factor E

Agrostis scabra
is a native species that does not outcompete or invade the habitat of
Agrostis rossiae.
Typically, these two species do not occur together. Additionally, we have no information to suggest that small population size or reduced genetic diversity limit
A. rossiae.
We conclude that the best scientific and commercial information available indicates that
Agrostis rossiae
is not in danger of extinction or likely to become so within the foreseeable future because of competition or hybridization, small population size, or reduced genetic diversity.

Finding for
Agrostis rossiae

As required by the Act, we considered the five factors in assessing whether
Agrostis rossiae
is threatened or endangered throughout all of its range. We examined the best scientific and commercial information available regarding the past, present, and future threats faced by
A. rossiae.
We reviewed the petition, information available in our files, and other available published and unpublished information, and we consulted with recognized
A. rossiae
experts and other Federal and State agencies.

The primary factors potentially impacting
Agrostis rossiae
are visitor impacts, the invasion of
Agrostis scabra,
and changing thermal activity. However,
A. scabra
is a native species that typically does not compete with
A. rossiae,
the existing boardwalks and trails offer sufficient pathways for visitors to navigate around the thermal areas, and sufficient regulatory mechanisms exist to prevent human-caused changes to the thermal basin by groundwater or geothermal development. Other factors affecting
A. rossiae
—including nonnative invasive plants, drought, small population size, and genetic diversity—are either limited in scope, or lacking evidence apparent to us indicating that they adversely impact the species as a whole. We have no evidence that overutilization, disease, or predation are affecting this species. Although climate change may impact the species in the future, we do not have enough information to determine that climate change will elicit a species-level response from
A. rossiae.
Based on our knowledge of the species, the regulatory mechanisms to protect the species appear appropriate.

Based on our review of the best available scientific and commercial information pertaining to the five factors, we find that the threats are not of sufficient imminence, intensity, or magnitude to indicate that
Agrostis rossiae
is in danger of extinction (endangered), or likely to become endangered within the foreseeable future (threatened), throughout all of its range. Therefore, we find that listing
A. rossiae
as a threatened or endangered species is not warranted throughout all of its range.

Significant Portion of the Range

Having determined that
Agrostis rossiae
does not meet the definition of a threatened or endangered species, we must next consider whether there are any significant portions of the range where
A. rossiae
is in danger of extinction or is likely to become endangered in the foreseeable future.

In determining whether
Agrostis rossiae
is threatened or endangered in a significant portion of its range, we first addressed whether any portions of the range of
A. rossiae
warrant further consideration. We evaluated the current range of
A. rossiae
to determine if there is any apparent geographic concentration of the primary stressors potentially affecting the species including visitor-related impacts (trampling), changing thermal activity, nonnative invasive plants, drought, small population size, and genetic diversity. This species' small range suggests that stressors are likely to affect it in a uniform manner throughout its range. Furthermore, we found the stressors are not of sufficient imminence, intensity, magnitude, or geographically concentrated such that it warrants evaluating whether a portion of the range is significant under the Act. We do not find that
A. rossiae
is in danger of extinction now, nor is it likely to become endangered within the foreseeable future throughout all or a significant portion of its range. Therefore, listing
A. rossiae
as threatened or endangered under the Act is not warranted at this time.

We request that you submit any new information concerning the status of, or threats to,
Agrostis rossiae
to our Wyoming Ecological Services Field Office (see
ADDRESSES
section) whenever it becomes available. New information will help us monitor
A. rossiae
and encourage its conservation. If an emergency situation develops for
A. rossiae,
or any other species, we will act to provide immediate protection.

Species Information for
Astragalus proimanthus

Species Description

Astragalus proimanthus
is a mat-forming, stemless, perennial herb measuring 2 to 3 dm (7.9 to 11.8 in.) in diameter (Fertig 2001, unpaginated) and up to 4 cm (1.6 in.) in height (Dorn 1979
in litt.,
unpaginated). The densely clustered, 1.0- to 3.5-cm-long (0.39- to 1.38-in.-long) leaves are divided into three narrow, 5- to 9-mm-long (0.2- to 0.4-in.-long) leaflets (small leaflike divisions of a larger compound leaf) (Fertig and Welp 2001, p. 7). The plants are covered with fine hairs and appear silvery, with leaflets that are equally hairy on both sides (Barneby 1964, p. 1153). The 17-mm-long (0.67-in.-long), asymmetrical, pea-like flowers have five petals: one large broad upper petal, two side petals, and two lower petals that form a canoe shape (Fertig and Welp 2001, p. 7). The broad upper petal, called the banner petal, is constricted along the midline, forming a fiddle shape (Roberts 1977, p. 63). The yellow to whitish flowers are often tinged with lavender or pink, especially near the center, and occur in pairs at the base of the leaves (Fertig and Welp 2001, p. 7). This plant has a taproot that is woody and branching (Barneby 1964, p. 1153).

Discovery and Taxonomy

The first specimens of
Astragalus proimanthus
were discovered and collected 9.7 km (6 mi) north of the town of McKinnon (Sweetwater County, Wyoming) on June 13, 1946, by H.C. Ripely and R.C. Barneby (Barneby 1964, p. 1154). A second population was located in 1961 (Barneby 1964, p. 1154). The population discovered in 1961 was collected from and revisited multiple times in the decades that followed; however, the population discovered in 1946 could not be relocated after multiple attempts (Fertig and Welp 2001, p. 8). In 2000, two populations were discovered, one of which may be the original site collected by Barneby in 1946 as this population was found 9.7 km (6 mi) north of the town of McKinnon (Fertig and Welp 2001, p. 9).

The flowering plant genus
Astragalus
is the largest genus of vascular plants (Montana Plant Life 2010, unpaginated). With the common names “milk-vetch” or “locoweed” (family Fabaceae or Leguminosae), the genus contains more than 2,000 species, which are distributed worldwide, although they are primarily found in the northern hemisphere (Barneby 1989, p. 1; Montana Plant Life 2010, unpaginated). Based on similar morphological features of the flower, calyx (collective term for the sepals, which are the green, leaflike structures that protect the delicate inner parts of the flower while it is developing), and fruits,
Astragalus proimanthus
is in a taxonomic grouping within
Oropahca
(subgenus) with
Astragalus gilviflorus
(Dubois milkvetch) and
Astragalus hyalinus

(summer milkvetch), which both occur in Wyoming (Fertig and Welp 2001, p. 6).
A. proimanthus
has been considered a descendant of
A. hyalinus
(Roberts 1977, p. 63).
A. proimanthus
is similar to
A. hyalinus
in its dwarf habit of growth and short flower with fiddle-shaped banner petal, but it is dissimilar in having smooth, hairless petals and an earlier flowering period (by a month or so) (Barneby 1964, p. 1154). Additionally,
A. proimanthus
grows in a small, compact form and not in a large, highly curved cushion characteristic of
A. hyalinus. A.

proimanthus
resembles
A. gilviflorus
in its growth form and has a similar range of numbers of seeds in the fruits; however, unlike
A. gilviflorus,
it has narrow, oval-shaped fruit and short, differently shaped banner petals (Barneby 1964, p. 1154). The only other
Astragalus
species in Wyoming with three leaflets have smaller flowers than
A. proimanthus
(Fertig 1994, unpaginated). All species within the subgenus
Oropahca
have 12 chromosomes (Roberts 1977, p. 1), but it is unknown if they are interfertile (capable of cross-pollinating or breeding with other
Astragalus
species) (Fertig and Welp 2001, p. 14). No evidence of hybridization between
A. proimanthus
and other
Astragalus
species has been documented (Fertig and Welp 2001, p. 14). Based on this information, we recognize
A. proimanthus
as a valid species and a listable entity.

Biology and Life History

Astragalus proimanthus
(precocious milkvetch) is named for its early flowering period. It has been observed in flower as early as April 28, and it may continue to bloom until mid-June (Fertig and Welp 2001, p. 14).
Astragalus
species are typically insect-pollinated; however, we have no information specific to
A. proimanthus
(Heidel 2003, p. 19). Both insects and birds have been observed visiting the flowers of
A. proimanthus
and may be involved in pollination (Fertig and Welp 2001, p. 14). Fruits are continuously produced from mid-May through late July (Roberts 1977, pp. 43, 97). The narrow, oval fruit pods (7 to 10 mm (0.28 to 0.39 in.) long) are attached to the stems and are covered in dense, fine hair (Fertig and Welp 2001, p. 7). The fruit pods contain 11 to 14 seeds (Barneby 1964, p. 1154) that are brown and 2.0 to 3.1 mm (0.08 to 0.12 in.) long (Roberts 1977, p. 64). Fruit production may be limited during drought years as evidenced by low fruiting rates observed in 2000 (Fertig and Welp 2001, p. 14). Due to the absence of seed structures (
e.g.,
winged edges) to enhance dispersal, seed dispersal appears passive and limited to short distances (Fertig and Welp 2001, p. 14).

Although
Astragalus proimanthus
is perennial, its lifespan may be shorter than is commonly assumed for mat-forming perennials, as is evidenced by shifts in location of plant subpopulations and disappearances of previously documented plant occurrences (Fertig and Welp 2001, pp. 13-14, 17). Longevity is an important life-history trait for the persistence and survival of species occurring in harsh environments where recruitment (reproductive success) is variable and unpredictable (Garcia
et al.
2008, p. 261).

Habitat

Astragalus proimanthus
is a narrow endemic occurring only on the shale bluffs of the Henrys Fork River, near the town of McKinnon, which is in the southern Green River Basin of southwestern Sweetwater County, Wyoming (Fertig and Welp 2001, p. 8). Sparsely vegetated rims and gullied upper slopes of benches, bluffs, and mesa-like ridges at elevations of 1,950 to 2,195 m (6,400 to 7,200 ft) provide habitat for
A. proimanthus
(Fertig and Welp 2001, p. 11).

Astragalus proimanthus
inhabits cushion plant and bunchgrass communities dominated by
Phlox hoodii
(spiny phlox or carpet phlox)
, Haplopappus nuttallii
(rayless aster)
, Cryptantha sericea
(silky cryptantha), and
Elymus spicatus
(bluebunch wheatgrass) in openings within
Artemisia tridentata
(big sagebrush) and grasslands intermixed with
Juniperus osteosperma
(Utah juniper) (Fertig and Welp 2001, p. 11).
A. proimanthus
also occurs on gentle slopes at the base of ridges within a matrix of
Artemisia nova
(black sagebrush)
, Sarcobatus vermiculatus
(greasewood),
J. osteosperma,
and
Grayia spinosa
(spiny hopsage) (Fertig and Welp 2001, p. 11). This species grows in fine-textured limestone shale clays that are dry, shallow, and covered by a dense layer of coarse cobbles, whitish flakey shale, and dark volcanic rock (Fertig and Welp 2001, pp. 11-12).

Individual
Astragalus proimanthus
plants are often separated by apparently suitable, nonvegetated habitat, and

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2011-13910. Public record. Not legal advice.