Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Astragalus ampullarioides, 15966-16002 [06-2840]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 71, Number 60 (Wednesday, March 29, 2006)]
[Proposed Rules]
[Pages 15966-16002]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 06-2840]



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Part III





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants--Designation of Critical 
Habitat; Proposed Rule

Federal Register / Vol. 71, No. 60 / Wednesday, March 29, 2006 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AU45


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for Astragalus ampullarioides (Shivwits Milk-Vetch) 
and Astragalus holmgreniorum (Holmgren Milk-Vetch)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), propose to 
designate critical habitat for two endangered plants, Astragalus 
ampullarioides (Shivwits milk-vetch) and Astragalus holmgreniorum 
(Holmgren milk-vetch), pursuant to the Endangered Species Act of 1973, 
as amended (Act or ESA). In total, approximately 2,620 hectares (ha) 
(6,475 acres (ac)) fall within the boundaries of the proposed critical 
habitat designation for A. holmgreniorum in Mohave County, Arizona, and 
Washington County, Utah, and approximately 980 ha (2,421 ac) fall 
within the boundaries of the proposed critical habitat designation for 
A. ampullarioides in Washington County, Utah.

DATES: We will accept comments from all interested parties until May 
30, 2006. We must receive requests for public hearings, in writing, at 
the address shown in the ADDRESSES section by May 15, 2006.

ADDRESSES: If you wish to comment, you may submit your comments and 
materials concerning this proposal by any one of several methods:
    1. You may submit written comments and information to Henry Maddux, 
Field Supervisor, U.S. Fish and Wildlife Service, Utah Fish and 
Wildlife Office, 2369 West Orton Circle, Suite 50, West Valley City, 
Utah 84119.
    2. You may hand-deliver written comments to our office, at the 
above address.
    3. You may send comments by electronic mail (e-mail) to 
hsmilkvetch@fws.gov. Please see Public Comments Solicited section below 
for file format and other information about electronic filing.
    4. You may fax your comments to 801-975-3331.
    5. You may submit comments via the Federal E-Rulemaking Portal at 
https://www.regulations.gov.
    Comments and materials received, as well as supporting 
documentation used in the preparation of this proposed rule, will be 
available for public inspection, by appointment, during normal business 
hours at the Utah Fish and Wildlife Office at the above address.

FOR FURTHER INFORMATION CONTACT: Field Supervisor, Utah Fish and 
Wildlife Office, 2369 West Orton Circle, Suite 50, West Valley City, 
Utah 84119. (telephone 801-975-3330; facsimile 801-975-3331).

SUPPLEMENTARY INFORMATION:

Public Comments Solicited

    We intend that any final action resulting from this proposal will 
be as accurate and as effective as possible. Therefore, comments or 
suggestions from the public, other concerned governmental agencies, the 
scientific community, industry, or any other interested party 
concerning this proposed rule are hereby solicited. Comments 
particularly are sought concerning:
    (1) The reasons any habitat should or should not be determined to 
be critical habitat as provided by section 4 of the Act, including 
whether the benefit of designation will outweigh any threats to the 
species due to designation;
    (2) Specific information on the amount and distribution of 
Astragalus holmgreniorum and A. ampullarioides habitat, and what 
habitat has features essential to the conservation of the species and 
why;
    (3) Specific information on the potential significance of a small 
site of Astragalus holmgreniorum, found north of Atkinville wash and 
west of Interstate Highway 15 (I-15) and not currently included in the 
proposed designation, to the conservation of the species (see Occupied 
Area not Included in Proposal);
    (4) Information regarding the inclusion of: (a) Occupied habitat 
for Astragalus holmgreniorum and A. ampullarioides found in intervening 
areas of I-15 (i.e., between the northbound and southbound lanes and 
within the highway right-of-way but outside the highway prism) (see 
Proposed Critical Habitat Designation for A. holmgreniorum, Subunit 1a: 
State Line, and Proposed Critical Habitat Designation for A. 
ampullarioides, Subunit 4a: Harrisburg Bench and Cottonwood); and (b) 
the intervening lands between occupied sites in Arizona (see Proposed 
Critical Habitat Designation for A. holmgreniorum, Subunit 1a: State 
Line);
    (5) Information regarding the benefits of excluding specific lands 
from, or including specific lands in, the designation of critical 
habitat including but not limited to, lands managed by Shivwits Band of 
Paiutes, Utah School and Institutional Trust Lands Administration 
(SITLA), Arizona State Land Department (ASLD), and lands recently 
burned due to wildfire (see Proposed Critical Habitat Designation for 
Astragalus holmgreniorum, Unit 4a);
    (6) Land use designations and current or planned activities in the 
subject areas and their possible impacts on proposed critical habitat;
    (7) Any foreseeable economic, national security, or other potential 
impacts resulting from the proposed designation and, in particular, any 
impacts on small entities; and
    (8) Whether our approach to designating critical habitat could be 
improved or modified in any way to provide for greater public 
participation and understanding, or to assist us in accommodating 
public concerns and comments.
    If you wish to comment, you may submit your comments and materials 
concerning this proposal by any one of several methods (see ADDRESSES 
section). Please submit Internet comments to hsmilkvetch@fws.gov in 
ASCII file format and avoid the use of special characters or any form 
of encryption. Please also include ``Attn: Shivwits or Holmgren milk-
vetch'' in your e-mail subject header and your name and return address 
in the body of your message. If you do not receive a confirmation from 
the system that we have received your Internet message, contact us 
directly by calling our Utah Fish and Wildlife Office at phone number 
801-975-3330. Please note that the Internet address hsmilkvetch@fws.gov 
will be closed at the termination of the public comment period.
    Our practice is to make comments, including names and home 
addresses of respondents, available for public review during regular 
business hours. Individual respondents may request that we withhold 
their home addresses from the rulemaking record, which we will honor to 
the extent allowable by law. There also may be circumstances in which 
we would withhold from the rulemaking record a respondent's identity, 
as allowable by law. If you wish us to withhold your name and/or 
address, you must state this prominently at the beginning of your 
comment, but you should be aware that the Service may be required to 
disclose your name and address pursuant to the Freedom of Information 
Act. However, we will not consider anonymous comments. We will make all 
submissions from organizations or businesses, and from individuals

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identifying themselves as representatives or officials of organizations 
or businesses, available for public inspection in their entirety. 
Comments and materials received will be available for public 
inspection, by appointment, during normal business hours at the above 
address.

Role of Critical Habitat in Actual Practice of Administering and 
Implementing the ESA

    Attention to and protection of habitat is paramount to successful 
conservation actions. The role that designation of critical habitat 
plays in protecting habitat of listed species, however, is often 
misunderstood. As discussed in more detail below in the discussion of 
exclusions under ESA section 4(b)(2), there are significant limitations 
on the regulatory effect of designation under ESA section 7(a)(2). In 
brief, (1) designation provides additional protection to habitat only 
where there is a Federal nexus; (2) the protection is relevant only 
when, in the absence of designation, destruction or adverse 
modification of the critical habitat would in fact take place (in other 
words, other statutory or regulatory protections, policies, or other 
factors relevant to agency decision-making would not prevent the 
destruction or adverse modification); and (3) designation of critical 
habitat triggers the prohibition of destruction or adverse modification 
of that habitat, but it does not require specific actions to restore or 
improve habitat.
    Currently, only 470 species, or 37 percent of the 1,264 listed 
species in the United States under the jurisdiction of the Service, 
have designated critical habitat. We address the habitat needs of all 
1,264 listed species through conservation mechanisms such as listing, 
section 7 consultations, the section 4 recovery planning process, the 
section 9 protective prohibitions of unauthorized take, section 6 
funding to the States, the section 10 incidental take permit process, 
and cooperative, nonregulatory efforts with private landowners. The 
Service believes that it is these measures that may make the difference 
between extinction and survival for many species.
    In considering exclusions of areas proposed for designation, we 
evaluated the benefits of designation in light of Gifford Pinchot Task 
Force v. United States Fish and Wildlife Service. In that case, the 
Ninth Circuit invalidated the Service's regulation defining 
``destruction or adverse modification of critical habitat.'' In 
response, on December 9, 2004, the Director issued guidance to be 
considered in making section 7 adverse modification determinations. 
This proposed critical habitat designation does not use the invalidated 
regulation in our consideration of the benefits of including areas in 
this final designation. The Service will carefully manage future 
consultations that analyze impacts to designated critical habitat, 
particularly those that appear to be resulting in an adverse 
modification determination. Such consultations will be reviewed by the 
Regional Office prior to finalizing to ensure that an adequate analysis 
has been conducted that is informed by the Director's guidance.
    On the other hand, to the extent that designation of critical 
habitat provides protection, that protection can come at significant 
social and economic cost. In addition, the mere administrative process 
of designation of critical habitat is expensive, time-consuming, and 
controversial. The current statutory framework of critical habitat, 
combined with past judicial interpretations of the statute, make 
critical habitat the subject of excessive litigation. As a result, 
critical habitat designations are driven by litigation and courts 
rather than biology, and made at a time and under a time frame that 
limits our ability to obtain and evaluate the scientific and other 
information required to make the designation most meaningful.
    In light of these circumstances, the Service believes that 
additional agency discretion would allow our focus to return to those 
actions that provide the greatest benefit to the species most in need 
of protection.

Procedural and Resource Difficulties in Designating Critical Habitat

    We have been inundated with lawsuits for our failure to designate 
critical habitat, and we face a growing number of lawsuits challenging 
critical habitat determinations once they are made. These lawsuits have 
subjected the Service to an ever-increasing series of court orders and 
court-approved settlement agreements, compliance with which now 
consumes nearly the entire listing program budget. This leaves the 
Service with little ability to prioritize its activities to direct 
scarce listing resources to the listing program actions with the most 
biologically urgent species conservation needs.
    The consequence of the critical habitat litigation activity is that 
limited listing funds are used to defend active lawsuits, to respond to 
Notices of Intent (NOIs) to sue relative to critical habitat, and to 
comply with the growing number of adverse court orders. As a result, 
listing petition responses, the Service's own proposals to list 
critically imperiled species, and final listing determinations on 
existing proposals are all significantly delayed.
    The accelerated schedules of court-ordered designations have left 
the Service with limited ability to provide for public participation or 
to ensure a defect-free rulemaking process before making decisions on 
listing and critical habitat proposals, due to the risks associated 
with noncompliance with judicially imposed deadlines. This in turn 
fosters a second round of litigation in which those who fear adverse 
impacts from critical habitat designations challenge those 
designations. The cycle of litigation appears endless, and is very 
expensive, thus diverting resources from conservation actions that may 
provide relatively more benefit to imperiled species.
    The costs resulting from the designation include legal costs, the 
cost of preparation and publication of the designation, the analysis of 
the economic effects and the cost of requesting and responding to 
public comment, and in some cases the costs of compliance with the 
National Environmental Policy Act (NEPA). These costs, which are not 
required for many other conservation actions, directly reduce the funds 
available for direct and tangible conservation actions.

Background

    We intend to discuss only those topics directly relevant to the 
designation of critical habitat in this proposed rule. For more 
information on the Astragalus holmgreniorum and A. ampullarioides refer 
to the final listing rule published in the Federal Register on 
September 28, 2001 (66 FR 49560).
    Both Astragalus holmgreniorum and A. ampullarioides are members of 
the pea family (Fabaceae or Leguminosae). A. holmgreniorum is found in 
both Washington County, Utah (UT), and Mohave County, Arizona (AZ), 
while A. ampullarioides is only found in Washington County, UT. Both 
species are narrowly distributed Mojave Desert endemics. Three 
populations of A. holmgreniorum and five populations of A. 
ampullarioides are known to exist (66 FR 49560; September 28, 2001). 
However, the distribution of plants within these populations is not 
always continuous; therefore, some populations are split into more than 
one site or proposed critical habitat unit.
    For the purposes of this proposed rule, the term ``population'' 
refers to an area of species concentration of either Astragalus 
holmgreniorum or A. ampullarioides individuals. The term ``occurrence'' 
indicates a record of one

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or more individual plants. A ``site'' refers to the land that supports 
individuals of the species, while a ``unit'' refers to specific sites 
that are being considered for critical habitat designation.

Astragalus holmgreniorum

    All known populations of Astragalus holmgreniorum occur within 
approximately 16 kilometers (km) (10 miles (mi)) of St. George, UT in 
Washington County, UT and in Mohave County, AZ. Populations are found 
between 756 and 914 meters (m) (2,480 and 3,000 feet (ft)) in elevation 
in areas that drain to the Santa Clara and Virgin rivers. The landscape 
has small and large hill and plateau formations which are broken up by 
water erosion. A. holmgreniorum is most frequently found on the skirt 
edges of hill and plateau formations, slightly above or on the edge of 
drainage areas (e.g., Harper and Van Buren 1997, 2004; Service, 
unpublished data, 2005). In areas where A. holmgreniorum is found, a 
large portion of the soil surface is non-vegetated, and is 
characterized by small stone and gravel deposits (Van Buren and Harper 
2003a). A. holmgreniorum frequently occur near intermittent drainage 
and receive ``run on'' water from nearby sloping areas (Harper 1997; 
Harper and Van Buren 1997). This, combined with slower evaporation due 
to shading produced by the small stone and gravel, may create better 
water relations in excess of regional rainfall (Harper 1997; Harper and 
Van Buren 1997).
    Astragalus holmgreniorum is a short-lived perennial; few plants 
live past three years, with 4 years being the oldest documented 
lifespan (Stubben 1997; Van Buren and Harper 2003a). Second-year and 
older plants appear several weeks before seedlings, generally in late 
February or early March. The best time to detect the species is while 
it is producing flowers (typically between March and April) and fruit 
(the majority of plants set fruits by the end of April). Seed pods are 
persistent until the end of May. Plants die back to roots between late 
May and mid-June (Van Buren and Harper 2003a).
    Annual fluctuations in the number of individuals within a 
population are great. Years with adequate precipitation produced a 
population estimated at 10,000 individuals, while populations in dry 
years may be as few as 500 individuals (Van Buren and Harper 2003a). 
Surveys conducted in different areas in 2003 and 2004 found individual 
numbers at 12,315 and 15,902 respectively (Van Buren 2003; Van Buren 
2004). These more intensive surveys indicate that in some years 
population numbers are higher than the 10,000 individuals estimated at 
the time of the listing rule. However, surveys in 2003 and 2004 
occurred in the spring and nearly all individuals counted were 
seedlings. More seedlings are found when precipitation in the first 
quarter of the year is higher (Van Buren and Harper 2003a). In the most 
recent years (2000, 2001, 2003, 2004), high flushes of seedlings have 
been coupled with a low survivorship rate (58.9 to 96.8 percent 
mortality) most likely due to the timing of precipitation; this 
mortality has resulted in relatively few reproductive adults (Van Buren 
and Harper 2004a). There is not a current total population estimate.
    Although the landscape holds an unknown quantity of seeds (referred 
to as a seed bank), high mortality may be depleting the seed bank (Van 
Buren 2004). Low survivorship and reproductive results would make this 
species vulnerable to extinction due to chance events, in the event 
that the population declines. In addition, in relationship to genetic 
fitness, seed germination may decrease as a population declines in size 
(Menges 1991; Heschel & Paige 1995). According to Menges (1990), if a 
population is to survive, offspring must be produced in quantity to 
replace the parent population. Currently, A. holmgreniorum seedling 
mortality continues to be very high, and adults are lacking (Van Buren 
2003 and 2004; Van Buren and Harper 2004a).
    Habitat is often dynamic, and species may move from one area to 
another over time. Seeds are thought to be dispersed by water as plants 
are generally found on the skirt edges of washes or in run-off channels 
around mounds (Harper and Van Buren 1997; Van Buren and Harper 2003a). 
Rodents and smaller ground-dwelling birds are likely other dispersal 
agents (Dr. Stanley Welsh, Brigham Young University, pers. comm. 2005).
    Astragalus holmgreniorum does not reproduce through vegetative 
methods; therefore, the setting of seed is necessary for future 
offspring. Flowers on some A. holmgreniorum plants can produce fruit 
without insect visitation (i.e., autogamously) (Tepedino 2005). 
However, self-fertilized flowers produced fewer fruits, and this 
ultimately negatively influences the number of offspring. A loss in 
pollinators could decrease genetic diversity and population fitness 
(Tepedino 2005).

Astragalus ampullarioides

    All known populations of Astragalus ampullarioides occur within 
Washington County, UT. Locations of A. ampullarioides populations are 
associated with the Chinle Formation, an often purple-hued patch of 
soft clay soil (Harper and Van Buren 1997; Stubben 1997). Isolated 
outcrops of the Chinle formation are found around St. George, UT 
(Armstrong and Harper 1991; Stubben 1997). This substrate, which is 
light and airy when dry, expands greatly with precipitation, becoming 
slick and glue-like (Harper 1997). In dry periods, this soil is 
considered unstable (Van Buren and Harper 2003b). During soil 
expansion, areas rise up into mounds (Harper 1997). Equal contraction 
upon drying often results in the formation of deep, wide cracks (Harper 
1997). This quality tends to constrict root systems so that few 
perennial plants persist on the Chinle formation (Harper 1997). Within 
Zion National Park (Zion NP), known sites of A. ampullarioides may 
possibly contain materials from later geologic formations.
    Astragalus ampullarioides populations are found between 920 to 1330 
m (3,018 to 4,367 ft) in elevation. Because occupied sites are small in 
area, it is difficult to link the presence of A. ampullarioides to any 
given soil type. Soil series information for 6 locations, representing 
42 A. ampullarioides occurrences, lacked strong correlations between 
presence of A. ampullarioides and any given soil type (Service, 
unpublished, 2005). A. ampullarioides is documented from the following 
soil types described by USDA et al. (1977): Stony colluvial land; 
Naplene silt loam, 2 to 6 percent slope; Eroded land-Shalet complex; 
Badland, very steep; Mathis-Rock outcrop complex, 20 to 50 percent 
slopes; Rock land, stony; Bond sandy loam, 1 to 10 percent; Clovis fine 
sandy loam, 1 to 5 percent slopes; Badland; and Rock land Hobog 
association (Service, unpublished, 2005).
    Astragalus ampullarioides is a perennial herb. Its lifespan is 
unknown, but available data indicate a lifespan of at least 9 years 
(Van Buren and Harper 2004b). Flowering occurs between March and late 
May. In most years, plants dry up by the end of June; however, vestiges 
of dried plants may persist longer. The perennial rootstock allows A. 
ampullarioides to survive dry years; in a drought year (e.g., 2002) 
plants may not emerge (Van Buren and Harper 2003b). Dormancy is one 
documented method by which longer-lived plant species can survive 
changing climatic conditions, particularly in areas

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with variable and unpredictable rainfall (Epling and Lewis 1952). 
Epling and Lewis (1952) indicate that the adaptive traits of a plant 
species utilizing dormancy, with some individuals remaining dormant in 
one growing season while others develop and reproduce, produces 
populations with some resiliency to environmental fluctuation.
    Due to climatic or other conditions, the number of Astragalus 
ampullarioides individuals documented in a given year at a given site 
varies. The total number of A. ampullarioides individuals was estimated 
at 1,000 individuals at the time of listing, with numbers in Zion NP 
estimated at 300 to 500 individuals (R. Van Buren 2000, in 66 FR 
49560). More recent site visits and surveys at Zion NP have expanded 
this number to 1,500 individuals (J. Alexander, pers. comm. 2004). 
Yearly information at other sites has varied, and total numbers are 
likely to be under 2,000 individuals (Dr. Renee Van Buren, Utah Valley 
State College, pers. comm. 2005). Variables (such as plant dormancy and 
population shift due to extinction and colonization of new sites) make 
estimating the total number of individuals in any given year difficult.
    According to Van Buren and Harper (2003a), the number of new 
Astragalus ampullarioides seedlings is related to precipitation in the 
year of observation, while percent mortality reflects moisture 
relations experienced in the prior year. Excluding 2002, when plants 
were not seen due to extreme drought conditions, the percent of adults 
and overall representation of age classes documented at a single site 
(Pahcoon Spring Wash) is considered stable (Van Buren and Harper 2003a; 
Van Buren and Harper 2004b). In the years 2000, 2001, 2003, 2004, 
seedlings comprised 7.5 to 54 percent of the population, and adults 
ranged from 40 to 77 percent (Van Buren and Harper 2004b). However, 
data on population size, reproductive output, and percent survivorship 
indicate a decline occurred in conjunction with severe drought in 2002 
(Van Buren and Harper 2004b). The small population size of most A. 
ampullarioides populations and limited geographic range make these 
populations vulnerable to randomly occurring catastrophic events, as 
well as small-scale habitat degradation (66 FR 49560).
    No methods of seed dispersal have been documented. Water drainage 
patterns, landscape erosion, and soil slumping may contribute to the 
development of appropriate habitat sites and may move seeds within 
sites (Van Buren and Harper 2003). The disjunct populations of 
Astragalus ampullarioides suggest bird dispersal, as pockets of Chinle 
are sufficiently far apart (Dr. S. Welsh, pers. comm. 2005).

Previous Federal Actions

    For more information on previous Federal actions concerning the 
Astragalus holmgreniorum and A. ampullarioides, refer to the final 
listing rule published in the Federal Register on September 28, 2001 
(66 FR 49560).
    On September 27, 2004, Center of Biological Diversity and Utah 
Native Plant Society filed a lawsuit against the Department of Interior 
(DOI) and the Service. The plaintiffs alleged that we were in violation 
of the ESA because we had failed to designate critical habitat and we 
had not developed a recovery plan for the two species. On July 15, 
2005, a court settlement was approved with a proposed critical habitat 
designation to be submitted to the Federal Register by March 17, 2006, 
and a final critical habitat designation to be submitted to the Federal 
Register by December 16, 2006. Recovery planning for these species is 
ongoing; however, a recovery plan for these species has not yet been 
completed.

Critical Habitat

    Critical habitat is defined in section 3 of the ESA as: (i) The 
specific areas within the geographical area occupied by a species, at 
the time it is listed in accordance with the ESA, on which are found 
those physical or biological features (I) essential to the conservation 
of the species and (II) that may require special management 
considerations or protection; and (ii) specific areas outside the 
geographical area occupied by a species at the time it is listed, upon 
a determination that such areas are essential for the conservation of 
the species. Conservation, as defined under section 3 of the ESA means 
to use and the use of all methods and procedures which are necessary to 
bring any endangered species or threatened species to the point at 
which the measures provided pursuant to the ESA are no longer 
necessary. Such methods and procedures include, but are not limited to, 
all activities associated with scientific resources management such as 
research, census, law enforcement, habitat acquisition and maintenance, 
propagation, live trapping, and transplantation, and, in the 
extraordinary case where population pressures within a given ecosystem 
cannot be otherwise relieved, may include regulated taking.
    Critical habitat receives protection under section 7 of the ESA 
through the prohibition against destruction or adverse modification of 
critical habitat with regard to actions carried out, funded, or 
authorized by a Federal agency. Section 7 requires consultation on 
Federal actions that are likely to result in the destruction or adverse 
modification of critical habitat. The designation of critical habitat 
does not affect land ownership or establish a refuge, wilderness, 
reserve, preserve, or other conservation area. Such designation does 
not allow government or public access to private lands. Section 7 is a 
purely protective measure and does not require implementation of 
restoration, recovery, or enhancement measures.
    To be included in a critical habitat designation, the habitat 
within the area occupied by the species must first have features that 
are essential to the conservation of the species. Critical habitat 
designations identify, to the extent known using the best scientific 
data available, habitat areas that provide essential life cycle needs 
of the species (i.e., areas on which are found the primary constituent 
elements, as defined at 50 CFR 424.12(b)).
    Habitat occupied at the time of listing may be included in critical 
habitat only if the essential features thereon may require special 
management or protection. Thus, we do not include areas where existing 
management is sufficient to conserve the species. (As discussed below, 
such areas may also be excluded from critical habitat pursuant to 
section 4(b)(2).) Accordingly, when the best available scientific data 
do not demonstrate that the conservation needs of the species so 
require, we will not designate critical habitat in areas outside the 
geographical area occupied by the species at the time of listing. An 
area currently occupied by the species but was not known to be occupied 
at the time of listing will likely, but not always, be essential to the 
conservation of the species and, therefore, typically included in the 
critical habitat designation.
    The Service's Policy on Information Standards Under the ESA, 
published in the Federal Register on July 1, 1994 (59 FR 34271), and 
section 515 of the Treasury and General Government Appropriations Act 
for Fiscal Year 2001 (Pub. L. 106-554; H.R. 5658) and the associated 
Information Quality Guidelines issued by the Service, provide criteria, 
establish procedures, and provide guidance to ensure that decisions 
made by the Service represent the best scientific and commercial data 
available. They require Service biologists to the extent consistent 
with the ESA and with the use of the best

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scientific and commercial data available, to use primary and original 
sources of information as the basis for recommendations to designate 
critical habitat. When determining which areas are critical habitat, a 
primary source of information is generally the listing package for the 
species. Additional information sources include the recovery plan for 
the species, articles in peer-reviewed journals, conservation plans 
developed by States and counties, scientific status surveys and 
studies, biological assessments, or other unpublished materials and 
expert opinion or personal knowledge. All information is used in 
accordance with the provisions of section 515 of the Treasury and 
General Government Appropriations Act for Fiscal Year 2001 (Pub. L. 
106-554; H.R. 5658) and the associated Information Quality Guidelines 
issued by the Service.
    Section 4 of the ESA requires that we designate critical habitat on 
the basis of the best scientific data available. Habitat is often 
dynamic, and species may move from one area to another over time. 
Furthermore, we recognize that designation of critical habitat may not 
include all of the habitat areas that may eventually be determined to 
be necessary for the recovery of the species. For these reasons, 
critical habitat designations do not signal that habitat outside the 
designation is unimportant or may not be required for recovery.
    Areas that support populations, but are outside the critical 
habitat designation, will continue to be subject to conservation 
actions implemented under section 7(a)(1) of the ESA and to the 
regulatory protections afforded by the section 7(a)(2) jeopardy 
standard, as determined on the basis of the best available information 
at the time of the action. Federally-funded or permitted projects 
affecting listed species outside their designated critical habitat 
areas may still result in jeopardy findings in some cases. Similarly, 
critical habitat designations made on the basis of the best available 
information at the time of designation will not control the direction 
and substance of future recovery plans, habitat conservation plans, or 
other species conservation planning efforts if new information 
available to these planning efforts calls for a different outcome.

Methods

    As required by the section 4(b)(2) of the Act and its implementing 
regulations (50 CFR 424.12), we use the best scientific data available 
in determining areas that contain the physical and biological features 
that are essential to the conservation of Astragalus holmgreniorum and 
A. ampullarioides (see Primary Constituent Elements section). We 
reviewed available information that pertains to the habitat 
requirements of these species. This information included data from our 
files that we used for listing the species; biological surveys; peer-
reviewed articles; agency reports and databases; soil series maps, 
including regional Geographic Information System (GIS) coverages for 
Mohave County, AZ, and Washington County, UT; geologic maps; aerial 
photography; information provided from the Bureau of Land Management 
(BLM), Zion NP, and SITLA; and discussions with field experts. We also 
made several visits to A. holmgreniorum and A. ampullarioides sites 
with representatives from the BLM, SITLA, the Shivwits Band of the 
Pauite Tribe, and other botanical experts and interested parties.
    We utilized herbarium locations assembled by Armstrong and Harper 
(1991) and Lee Hughes, BLM Arizona, (pers. comm. 2005); hand-sketched 
reconnaissance records from the late 1980s and early 1990s; and 
location polygons provided by BLM (2004). In addition, we examined 
2,824 occurrence points for Astragalus holmgreniorum and 42 occurrence 
points for A. ampullarioides provided by SITLA, Zion NP, and Dr. R. Van 
Buren. Field surveyors gathered these points in 2003, 2004, and 2005 
using handheld Global Positioning System (GPS) units. Although these 
points may have some spatial errors due to positions of satellites and 
overlay of different map layers, we used them as reference for baseline 
information.
    The long-term conservation of both Astragalus holmgreniorum and A. 
ampullarioides is dependent upon the protection of existing populations 
and the maintenance of ecological functions within these sites, 
including: Connectivity within and between populations within close 
geographic proximity to facilitate pollinator activity and seed 
dispersal mechanisms; population expansion; and the ability to maintain 
these areas free of major ground-disturbing activities. The areas we 
are proposing to designate as critical habitat provide some or all of 
the habitat components essential for the conservation of the A. 
holmgreniorum and A. ampullarioides. We do not propose any areas 
outside the geographical area presently occupied by the species. In 
addition, information provided in comments on the proposed critical 
habitat designation and draft economic analysis will be evaluated and 
considered in the development of the final designation for A. 
holmgreniorum and A. ampullarioides.

Primary Constituent Elements

    Pursuant to our regulations, we are required to identify the known 
physical and biological features (PCEs) essential to the conservation 
of the two Astragalus species. These include, but are not limited to--
space for individual and population growth and for normal behavior; 
food, water, air, light, minerals, or other nutritional or 
physiological requirements; cover or shelter; sites for reproduction, 
germination, or seed dispersal; and habitats that are protected from 
disturbance or are representative of the historic geographical and 
ecological distributions of a species. All areas proposed as critical 
habitat for Astragalus holmgreniorum and A. ampullarioides are 
occupied, within the species' historic geographic range, and contain 
sufficient PCEs to support at least one life history function.
    The primary constituent elements required for Astragalus 
holmgreniorum and A. ampullarioides are derived from their biological 
needs as described in the Background section of this proposal. They 
include those habitat components essential for the biological needs of 
each species, including seed germination and seedling growth, flower 
production, pollination, seed set and fruit production, and genetic 
exchange.

Astragalus holmgreniorum

Space for Individual and Population Growth and Food, Water, Air, Light, 
Minerals or Other Nutritional or Physiological Requirements
    Astragalus holmgreniorum has a limited distribution; it is found 
only in a small area in UT and AZ. Within these areas, A. holmgreniorum 
requires appropriate soils, associated formations, slope, drainage and 
plant community within the landscape to provide space for individual 
and population growth and to provide food, water, air, light minerals 
or other nutritional or physiological requirements. In UT, A. 
holmgreniorum is found on the Virgin Limestone, upper redbed subunits 
of the Moenkopi formation, and on the Chinle shale formation (Petrified 
Forest member) with a thin gravel layer from the Shinarump Conglomerate 
member (Harper and Van Buren 1997). Sites in UT are most affiliated 
with the following soil series: Both Badland and Badland, very steep; 
Hobog-Rock Land association; Isom cobbly sandy loam, 3-30 percent 
slope; Eroded land-Shalet complex, warm (USDA et al., 1977).

[[Page 15971]]

Sites in AZ are believed to be associated with the Virgin Limestone 
member and middle red member of the Moenkopi Formation (L. Hughes, 
pers. comm. 2005). These sites may be affiliated with the following 
soil series: Ruesh very gravelly fine sandy loam, 3-20 percent slopes; 
Gypill-Hobog complex, 6-35 percent slopes; Gypill very cobbly sandy 
loam, 15-40 percent; and Hobog-Grapevine complex, 2-35 percent slopes 
(USDA et al. 2000).
    Astragalus holmgreniorum occurs at elevations from 756 to 914 m 
(2,480 to 3,000 ft) on sites with slight to moderate slope (Service, 
unpublished data, 2005). Slopes range from 0 to 46.55 percent (Service, 
unpublished, 2005), although most individuals of A. holmgreniorum are 
found between 1.54 and 14.01 percent slope (Service, unpublished data, 
2005).
    Astragalus holmgreniorum occurs in sparsely vegetated warm desert 
communities. Ninety-eight percent of known sites in UT occur within the 
landcover described as Sonora-Mojave Creosote-White Bursage Desert 
Scrub (NatureServe 2004). This classification contains a matrix of 
desert scrub, sparse to moderately dense (2 to 50 percent cover), found 
in the broad valleys, plains, and low hills of the Mojave and lower 
Sonora Deserts. A. holmgrenorium is not found within the lower Sonora 
Desert. Typical dominant shrubs within this landcover type are Larrea 
tridentata (creosote bush) and Ambrosia dumosa (white burrobush). 
However, in UT, areas where A. holmgreniorum is found are generally 
without Larrea tridentata and lack shrub density (Dr. R. Van Buren, 
pers. comm. 2005). In Arizona, the species occurs within Mohave Mixed 
Shrub and Mohave Creosote/Bursage habitats (Bennett, Kunzmann, and 
Graham 2004). Within this ecological system A. holmgreniorum is found 
in low vegetated areas where shrubs are sparse and creosote rarely 
resides.
    Woody plant species associated with Astragalus holmgreniorum are 
Acamptopappus sphaerocephalus (desert goldenhead), Ambrosia dumosa 
(white burrobush), Ephedra nevadensis (Neveda jointfire), E. torreyana 
(Torrey's jointfir), Krameria grayi (White ratany), K. parvifolia 
(range ratany), Lycium andersonii (Anderson wolfberry), Gutierrezia 
microcephala (threadleaf snakeweed), and G. sarothrae (broom 
snakeweed). Other commonly-associated, nonwoody species include: A. 
nuttallianus (small flowered milkvetch), Chaenactis sp. (pincushion 
flower), Cryptantha sp.(cryptantha), annual Eriogonum sp. (buckwheat), 
Eriogonum inflatum (desert trumpet), Hilaria rigida (big galleta), and 
Plantago patagonica (wholly plantain) (Armstrong and Harper 1991; Van 
Buren and Harper 2003a and b, 2004a). Depending on the moisture regime, 
A. holmgreniorum also can be seen with native annuals that are often 
ephemeral (seen only in the spring) and, like many Mohave Desert plant 
species, seasonally abundant based on climatic conditions.
Sites for Reproduction, Germination, Seed Dispersal or Pollination
    Astragalus holmgreniorum is a native species of sparsely vegetated 
warm desert communities. Sites for reproduction, germination, and seed 
dispersal, and pollination providers are found within the communities 
described above.
    Astragalus holmgreniorum relies solely on the production of seeds 
for reproduction. Optimal seed set occurs through insect visitation and 
pollination (Tepedino 2005). Thus, the presence of pollinator 
populations is essential to the conservation of A. holmgreniorum 
(Tepedino 2005). Bees require a sufficient quantity of flowers to 
attract and support their survivorship (Harper et al. 2000; Tepedino 
2005). Native bees, such as Anthophora coptognatha, A. dammersi, A. 
porterae, Anthophora sp., Eucera quadricincta, Osmia titusi, two types 
of Dialictus species, and the introduced honeybee, Apis mellifera, are 
the primary visitors and pollinators of A. holmgreniorum (Tepedino 
2005). The majority of pollinator species associated with A. 
holmgreniorum likely nest in the ground, either in vertical embankments 
or on flat surfaces (Tepedino 2005). Unlike other types of bee species 
who have aggregated nesting areas, the five anthophorid bees (A. 
coptognatha, A. dammersi, A. porterae, Anthophora sp., and Eucera 
quadricincta) have nests that are most likely dispersed and well-hidden 
(Tepedino 2005). The nesting substrate for O. titusi is unknown, while 
the two species of Dialictus nest in the ground.
    Many bees expend considerable effort to produce few offspring. 
Solitary bees, in conditions without predators and with abundant floral 
resources, have been shown to produce only 15-20 offspring per female 
(Tepedino 1979). Because solitary bees have low reproductive rates, 
their populations rebound slowly after habitat perturbations (Tepedino 
1979). Additionally, the lack of favorable natural habitat can 
negatively influence pollination productivity (Kremen et al. 2004). Bee 
populations fluctuate from year to year (Roubik 2001; Tepedino and 
Stanton 1980 in Tepedino 2005). Redundancy of pollinator species is 
important because a pollinator species may be abundant one year and 
less so the next year (Tepedino 2005). Maintaining a full suite of 
pollinators allows the likelihood that another pollinator species will 
stand in for a less abundant one (Tepedino 2005), and is essential in 
assuring adequate pollination.
    Several of the bees visiting Astragalus holmgreniorum are fairly 
generalized in their choices of flowers (Eucera quadricincta, 
Anthophora coptognatha, and two types of Dialictus); others are known 
to have flower preferences (Tepedino 2005). Anthophora porterae and 
Osmia titusi have a preference for plants in the legumes or pea family 
(Tepedino 2005). Anthophora porterae, a fast and effective forager, is 
frequently captured or observed visiting Astragalus flowers (Tepedino 
2005). Anthophora dammersi is also known to be a specialist of 
Camissonia and is known to inhabit only areas where Camissonia is 
present (Tepedino 2005).
    Bees have a limited foraging range strongly correlated to body size 
(Greenleaf, 2005; Steffan-Dewenter and Tscharntke 1999). Fragmentation 
of habitat can result in isolating plants from pollinator nesting 
sites. When the distance between plants and the natural habitats of 
pollinators increases, plant reproduction (as measured by mean seed 
set) can decline by as much as 50 percent in some plant species 
(Steffan-Dewenter and Tscharntke 1999). Optimal pollination occurs when 
there is abundance of individual pollinators and a species-rich bee 
community (Greenleaf 2005).
    Greenleaf (2005) defines the typical homing distance of a bee taxon 
as the distance at which 50 percent of individual bees of that taxon 
have the ability to return to their home (nest, etc). Pollinators for 
Astragalus holmgreniorum have average body sizes that correlate with 
typical homing distances of 0.1 to 2.9 km (0.06-1.8 mi), based on 
Greenleaf (2005). The pollinators with the smallest body size (which 
constitute one-third of A. holmgreniorum visitors) have typical homing 
distances of around 400 m (1,312 ft) or less (Service, unpublished, 
2005). A radius of 400 m (1,312 ft) around a single plant contains 
approximately 50 ha (124 ac). Thus, in the delineation of proposed 
critical habitat units when the units/subunits were smaller than 124 
ac, we expanded the boundary outward to encompass a full 124 ac to 
ensure that pollinators would have a sufficient land base to establish 
nesting sites and to provide pollinating services for A. holmgreniorum.

[[Page 15972]]

Disturbance, Protection, and the Historical Geographical Distributions
    The areas being proposed as critical habitat are representative of 
the known historic, geographical, and ecological distributions for 
Astragalus holmgreniorum. In total, three units are being proposed that 
correspond to the three populations described in the final listing rule 
(66 FR 49560, September 28, 2001). Within these units, three subunits 
are proposed for the first population and two subunits for the second 
population, while the third is a single site. All sites contribute to 
ecological distribution and function for this species by providing 
representation across the species' limited current range.
Primary Constituent Elements for Astragalus holmgreniorum
    Based on our current knowledge of the life history, biology, and 
ecology of the species and the requirements of the habitat to sustain 
the essential life history functions of the species, the primary 
constituent elements for A. holmgreniorum are:
    (1) Appropriate geological layers or soils that support individual 
Astragalus holmgreniorum plants. A. holmgreniorum is found on the 
Virgin Limestone member, middle red member, and upper red member of the 
Moenkopi Formation and the Petrified Forest member of the Chinle 
Formation (Harper and VanBuren 1997; L. Hughes, pers. comm. 2005). 
Associated soils are defined by USDA et al. (1977 and 2000 as Badland; 
Badland, very steep; Eroded land-Shalet complex, warm; Hobog-rock land 
association; Isom cobbly sandy loam; Ruesh very gravelly fine sandy 
loam; Gypill Hobog complex, 6-35 percent slopes; Gypill very cobbly 
sandy loam, 15-40 percent slopes; and Hobog-Grapevine complex, 2-35 
percent slopes. These soils are generally found at elevations from 756 
to 914 m (2,430 to 3,000 ft) and support the associated native plant 
species described above with low presence or lack of Larrea tridentata 
(creosote bush).
    (2) Topographic features/relief (mesas, ridge remnants, alluvial 
fans and fan terraces, their summits and backslopes, and gently rolling 
to steep swales) and the drainage areas along formation edges with 
little to moderate slope (0 to 20 percent).
    These topographic features/relief contribute to the soil substrate 
and vegetative community described above, natural weathering and 
erosion, and the natural surface and subsurface structure that provides 
minimally altered or unaltered hydrological conditions (e.g., 
seasonally available moisture from surface or subsurface runoff).
    (3) The presence of insect visitors or pollinators, such as 
Anthophora captognatha, A. damnersi, A. porterae, Anthophora sp., 
Eucera quadricincta, Omia titus, and two types of Dialictus sp.

Astragalus ampullarioides

Space for Individual and Population Growth, and Food, Water, Air, 
Light, Minerals or Other Nutritional or Physiological Requirements
    Astragalus ampullarioides has a limited distribution and is found 
on clay outcroppings associated with the Chinle Formation (Harper and 
Van Buren 1997; Stubben 1997) and possibly landslide materials from 
later geologic periods (Zion NP, unpublished, 2005) in a small area in 
UT. A. ampullarioides requires appropriate soils, associated 
formations, slope, drainage, and plant community within the landscape 
to provide space for individual and population growth and to provide 
food, water, air, light minerals or other nutritional or physiological 
requirements. The texture of this soil is approximately 48.9 percent 
clay (Van Buren and Harper 2003a). The high content of minerals non-
oxidized iron minerals gives the soils purplish red hues. These clay 
outcroppings are found in limited pockets in Washington County, UT. 
Topographic relief that contains the Chinle Formation is necessary to 
maintain the soil and natural hydrologic conditions upon which A. 
ampullarioides relies, such as surface or subsurface runoff, water 
erosion, and water drainages.
    Astragalus ampullarioides occurs at elevations from 920 to 1331 m 
(3,018 to 4,367 ft) on sites with slight to moderate slope. Individual 
sites range from 3.1 to 24 percent slope (Service, unpublished, 2005). 
Most individuals of A. ampullarioides are found between 4 and 14 
percent slope (Service, unpublished, 2005).
    Astragalus ampullarioides is found on sparsely vegetated soil 
outcroppings within a variety of plant communities. Living plant cover 
is low, approximately 12.3 percent of the landscape, with annual 
exotics representing a high proportion (approximately half) of plants 
seen (Van Buren and Harper 2003a and 2004b). Associated native plant 
species include annual forbs, such as annual species, Lotus humistratus 
(hairy deer vetch) and Plantago patagonica (woolly plantain); 
perennials, such as Calochortus flexuosus (sego lily) and Dichelostemma 
pulchellum (bluedicks); native grass, such as, Hilaria rigida (big 
galetta); and shrubs, such as Colegyne ramosissima (blackbrush) and 
Gutierrezia microcephala (broom snakeweed) (Van Buren and Harper 2003a 
and 2004b).
Sites for Reproduction, Germination, Seed Dispersal or Pollination
    Sites for reproduction, germination, and seed dispersal, and 
pollination providers are found within the sparsely vegetated soil 
outcroppings of the Chinle Formation and their surrounding communities. 
The Chinle Formation provides sites for reproduction, germination, and 
seed dispersal. However, habitat for pollinator nesting and foraging 
extend beyond occupied habitat of Astragalus ampullarioides because of 
the home range size of the pollinators and the need for most 
pollinators to visit a variety of plant species. Like A. holmgreniorum, 
A. ampullarioides relies solely on the production of seeds for 
reproduction; therefore, pollination is highly linked to its survival 
as a species. Automatic self-pollination (without insect visitation) 
produces significantly fewer seeds than the number produced through 
pollination or insect visitation (Tepedino 2005). A lack of pollinators 
would gradually decrease the number of seeds in the seed bank (Tepedino 
2005).
    For optimal pollination, many plants require a diversity of 
pollinators; these pollinators in turn rely upon a sufficient quantity 
of floral resources for their survivorship (Rathcke and Jules 1993; 
Steffan-Dewenter and Tscharntke 1999; Kremen et al. 2004; Greenleaf 
2005). A. ampullarioides has many of the same insect visitors as A. 
holmgreniorum (Anthophora coptognatha, A. dammersi, A. porterae, 
Anthophora sp., Apis mellifera, Eucera quadricincta, Osmia titusi, and 
two types of Dialictus species). Additionally, A. ampullarioides 
pollinators include Bombus morrisoni, Hoplitis grinnelli, Osmia 
clarescens, and O. marginata. Bombus morrisoni is one of the most 
abundant bumblebee species in the arid areas of Utah and is the most 
abundant bumblebee in Washington County (Tepedino 2005). Queens 
overwinter and nest in rodent holes, under bark, and in wood piles. B. 
morrisoni are social bumblebees. Worker B. morrisoni bumblebees are 
active for most or all of the flowering season and must be capable of 
gathering pollen and nectar from a variety of flowers. Most individual 
workers specialize on one or a few species of flowering plants during 
their lifetime of approximately 3 to 4 weeks. The other three species 
O. clarescens, O. marginata, and H.

[[Page 15973]]

grinnellii, are generalists that visit a wide range of flowers 
(Tepedino 2005).
    As with Astragalus holmgrenorium, the associated anthophorid bees 
for A. ampullarioides have well-hidden nests in the ground, either in 
vertical embankments or on flat surfaces. Osmia clarescens, O. 
marginata, and Hoplitis grinnellii nest in existing holes in wood made 
by other insects (e.g., beetles). O. clarescens is also known to make 
its nests in abandoned mud-dauber nests (Tepedino 2005; Tepedino, pers. 
comm. 2005).
    As with Astragalus holmgrenorium, reproduction, germination, and 
pollination of A. ampullarioides is accomplished by bee populations. If 
bees are to be kept active in the area where rare plants occur, then 
they must be provided with adequate flowers for the whole flight season 
(Tepedino 2005). Known pollinators for A. ampullarioides have body 
sizes that correlate with typical homing distances ranging from 0.06 mi 
to 1.8 mi (0.1 km to 2.9 km) (derived from Greenleaf, 2005). The 
smallest pollinators are limited in the range they can fly, with 
typical homing distances of around 400 m (1,312 ft) or less (Service, 
unpublished, 2005). A radius of 400 m (1,312 ft) around a single plant 
contains approximately 50 ha (124 ac). Thus, in the delineation of 
proposed critical habitat units when the units/subunits were smaller 
than 124 ac, we expanded the boundary outward to encompass a full 124 
ac to ensure that pollinators would have a sufficient land base to 
establish nesting sites and to provide pollinating services for A. 
ampullarioides.
Disturbance, Protection, and the Historical Geographical Distributions
    The areas being proposed as critical habitat are representative of 
the known historic, geographical, and ecological distributions for 
Astragalus ampullarioides. In total, we are proposing five units, which 
correspond to the five populations described in the final listing rule 
(66 FR 49560; September 28, 2001). We are dividing one unit into two 
subunits for the Harrisburg Junction population, which was described in 
the final listing rule as having four disjunct sites (66 FR 49560; 
September 28, 2001). All sites contribute to ecological distribution 
and function for this species by providing representation across the 
known occupied range of the species.
Primary Constituent Elements for A. ampullarioides
    Based on our current knowledge of the life history, biology, and 
ecology of the species, the primary constituent elements for A. 
ampullarioides are:
    (1) Outcroppings of soft clay soil, often purple-hued, within the 
Chinle Formation, at elevations from 920 to 1,330 m (3,018 to 4,367 
ft).
    Plant species that are characteristically found on these clay soils 
within the Chinle Formation and can indicate the presence of this PCE 
for A. ampullarioides are listed above under Space for Individual and 
Population Growth, and Food, Water, Air, Light, Minerals or Other 
Nutritional or Physiological Requirements.
    (2) Topographic features/relief, including alluvial fans and fan 
terraces, and gently rolling to steep swales that are often markedly 
dissected by water flow pathways from seasonal precipitation with 
little to moderate slope (3 to 24 percent).
    Associated topographic features/relief contribute to the soil 
substrate and vegetative community described above, natural weathering 
and erosion, and the natural surface and subsurface structure that 
provide minimally altered or unaltered hydrological conditions (e.g., 
seasonally available moisture from surface or subsurface runoff) upon 
which Astragalus ampullarioides depends.
    (3) The presence of insect visitors or pollinators, such as 
Anthophora captognatha, A. damnersi, A. porterae, Anthophora species, 
Eucera quadricincta, Bombus morrissonis, Hoplitis grinnelli, Osmia 
clarescens, O. marginata, O. titus, O. clavescens, and two types of 
Dialictus species.
    All areas designated as critical habitat for Astragalus 
holmgreniorum and Astragalus ampullarioides are within the geographic 
area occupied by the species and were known to be occupied at the time 
of listing. This proposed designation is designed for the conservation 
of PCEs necessary to support the life history functions that were the 
basis for the proposal for each species. Because not all life history 
functions require all the PCEs, not all proposed critical habitat will 
contain all the PCEs. Each of the areas proposed in this rule have been 
determined to contain sufficient PCEs to provide for one or more of the 
life history functions of Astragalus holmgreniorum or Astragalus 
ampullarioides. In some cases, the PCEs exist as a result of ongoing 
Federal actions. As a result, ongoing Federal actions at the time of 
designation will be included in the baseline in any consultation 
conducted subsequent to this designation.

Criteria Used To Identify Critical Habitat

    We are proposing to designate critical habitat for Astragalus 
holmgreniorum and A. ampullarioides on lands that we have determined 
were occupied at the time of listing and contain the identified primary 
constituent elements. In identifying proposed critical habitat units 
for A. holmgreniorum and A. ampullarioides, we proceeded through a 
multi-step process.
    We obtained records of A. holmgreniorum and A. ampullarioides 
distribution from BLM Arizona Strip Field Office (BLM AZ); BLM St. 
George Field Office (BLM UT); SITLA; Zion NP; Utah Valley State College 
(R. VanBuren, unpublished GIS data); and both published and unpublished 
documentation from our files. This information included BLM hand-mapped 
polygons that outlined occupied or potentially occupied habitats in AZ 
and UT, primarily developed prior to the species listing (66 FR 49560, 
September 28, 2001).
    For some sites, recent 2003 to 2005 survey information was 
available and evaluated to identify currently known plant locations 
(provided by Zion NP, BLM UT, BLM AZ, SITLA, and Van Buren). Although 
occupied sites may gradually change, recent survey results confirm that 
plant distribution is similar to known distributions at the time of 
listing (66 FR 49560; September 28, 2001).
    Our approach to delineating critical habitat units was applied in 
the following manner:
    (1) We overlayed plant locations into a GIS database. This provided 
us with the ability to examine slope, aspect, elevation, vegetation 
community, and topographic features, such as drainages. These 
datapoints verified and slightly expanded the previously recorded 
elevation ranges for both species. Additionally, we found no 
correlation between aspect and occurrence location for either species. 
Some affiliation of slope for both species was noted; however, 
statistical correlation was not conclusive.
    To better understand the landscape, we also examined soil series 
layers, aerial photography, and hardcopy geologic maps. For Astragalus 
holmgreniorum, we focused on soil type and topographic features to 
maintain slope and natural drainage; for A. ampullarioides topographic 
features to maintain slope and natural drainage were the focus. We were 
unable to find GIS layers pertaining to geologic survey. For this we 
visually compared known sites to hard-copy geologic maps. Since

[[Page 15974]]

the maps were not of sufficient resolution to further evaluate the 
purplish red clay soil found in small outcroppings within the Chinle 
Formation, aerial photography at times was employed to further our 
understanding of these areas. We verified that Astragalus 
ampullarioides is associated with the Petrified Forest member of the 
Chinle Formation and A. holmgreniorum is associated with the Virgin 
Limestone member, upper red member of the Moenkopi Formation, Chinle 
Shale, and Shinarump conglomerate member of the Chinle Formation 
(Harper and Van Buren 1997) and may also be affliated with the middle 
red member of the Moenkopi Formation (Lee Hughes, BLM AZ, pers. comm. 
2006).
    For both A. holmgreniorum and A. ampullarioides, we looked at soil 
survey layers. No two sites of A. ampullarioides contained the same 
type of United States Geological Survey (USGS) soil description. From 
this, we determined that the clay outcroppings associated with the 
Petrified Forest Member of the Chinle Formation on which A. 
ampullarioides is found may not be of size significant to be labeled 
under the USGS soil series. In Utah, A. holmgreniorum individuals are 
associated with Badland and Badland, very steep (84 percent); Hobog-
Rock land association (9 percent); and Isom cobbly sand loam, 3-30 
percent slope (5 percent). Although we lacked the same degree of 
information in Arizona, we found that documented sites appeared to be 
related to Ruesh very gravelly fine sandy loam, 3-20 percent slopes; 
Gypill-Hobog complex, 6-35 percent slopes; Gypill very cobbly sandy 
loam, 15-40 percent slopes; and Hobog-Grapevine complex, 2-35 percent 
slopes (as defined in USDA et al. 2000).
    (2) When appropriate, we used geographic features (e.g., ridge 
lines, valleys, streams, elevation) or manmade features (e.g., roads) 
that created an obvious boundary to delineate a unit area boundary. In 
some cases, we were unable to provide obvious boundaries, so unit 
boundaries were drawn to encompass PCEs on the basis of the best 
available information.
    (3) We then drew critical habitat boundaries that captured the 
locations, soils, and slopes elucidated under (1) above while 
considering the boundaries identified in (2) above. Critical habitat 
designations were then described and mapped using Universal Transverse 
Mercator (UTM) North American Datum 83 (NAD 83) coordinates.
    (4) Finally, when the resulting units were smaller than 124 acres, 
we increased the unit size to 124 acres by using the average travel 
distance for the pollinators of Astragalus holmgreniorum and A. 
ampullarioides. We believe that this increase in unit size is essential 
to ensure sufficient pollinator populations for the reproduction of A. 
holmgreniorum and A. ampullarioides. Specifically, where necessary, 
units or subunits were enlarged to 124 acres by including habitat 
within a 400 m (1,312 ft) radius of the known plant locations within 
the unit. This step applied to A. holmgreniorum subunits 2b and 3 and 
A. ampullarioides units 1, 2, 3, and subunit 4 a. Unit 3 for A. 
ampullarioides is bordered by development on its western edge; 
therefore, we did not incorporate 400 m (1,312 ft) on the western edge 
of Unit 3.
    The proposed critical habitat designation includes representatives 
of all known populations of Astragalus holmgreniorum and A. 
ampullarioides, and habitats that possess the physical and biological 
features essential to the conservation of the species and require 
special management considerations or protection. Application of these 
criteria: (1) Protects habitat that contain the PCEs in areas where A. 
holmgreniorum and A. ampullarioides are known to occur; (2) maintains 
the current ecological distribution to preserve genetic variation 
within the range of A. holmgreniorum and A. ampullarioides to minimize 
the effects of local extinction; (3) minimizes fragmentation by 
establishing contiguous occurrences and maintaining existing 
connectivity; (4) includes sufficient pollinator habitat; and (5) 
protects the seed bank to ensure long term persistence of the species.
    Much of the survey and field data on which this proposed 
designation is based represents observed individuals during one point 
in time. Due to annual population fluctuations associated with varying 
local environmental factors (e.g., precipitation, seed germination), it 
is likely that individual plants and occurrences exist but were not 
identified in recent surveys (Van Buren and Harper 2003b; 66 FR 49560, 
September 28, 2001). Identification of these areas as critical habitat 
ensures maintenance of connectivity between currently known occupied 
habitats over the long term. Gene flow is also maintained by securing 
sufficient area for pollinator habitats and travel corridors.
    These habitats also ensure protection of seed banks, seed 
dispersal, and pollinator services that are essential fo