Federal Register: December 15, 2010 (Volume 75, Number 240)
DOCID: fr15de10-21 FR Doc 2010-31225
DEPARTMENT OF THE INTERIOR
Workers Compensation Programs Office
CFR Citation: 50 CFR Part 17
FWS ID: [FWS-R6-ES-2010-0080; MO 92210-0-0008-B2]
NOTICE: Part V
DOCUMENT ACTION: Notice of 12-month petition finding.
Endangered and Threatened Wildlife and Plants; 12-Month Finding on a Petition To List Astragalus microcymbus and Astragalus schmolliae as Endangered or Threatened
DATES: The finding announced in this document was made on December 15, 2010.
We, the U.S. Fish and Wildlife Service (Service/USFWS), announce a 12month finding on a petition to list Astragalus microcymbus (skiff milkvetch) and Astragalus schmolliae (Schmoll's milkvetch) as endangered or threatened, and to designate critical habitat under the Endangered Species Act of 1973, as amended (Act). After a review of all the available scientific and commercial information, we find that listing A. microcymbus and A. schmolliae is warranted. However, currently listing of A. microcymbus and A. schmolliae is precluded by higher priority actions to amend the Lists of Endangered and Threatened Wildlife and Plants. Upon publication of this 12month petition finding, we will add A. microcymbus and A. schmolliae to our list of candidate species. We will make any determinations on critical habitat during development of the proposed listing rule. In any interim period, the status of the candidate taxon will be addressed through our annual Candidate Notice of Review.
Interior Department, Fish and Wildlife Service
Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.), requires that, for any petition to revise the Federal Lists of Endangered and Threatened Wildlife and Plants that contains substantial scientific or commercial information that listing the species may be warranted, we make a finding within 12 months of the date of receipt of the petition. In this finding, we will determine that the petitioned action is: (a) Not warranted, (b) warranted, or (c) warranted, but immediate proposal of a regulation implementing the petitioned action is precluded by other pending proposals to determine whether species are threatened or endangered, and expeditious progress is being made to add or remove qualified species from the Federal Lists of Endangered and Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires that we treat a petition for which the requested action is found to be warranted but precluded as though resubmitted on the date of such finding, that is, requiring a subsequent finding to be made within 12 months. We must publish these 12month findings in the Federal Register.
In accordance with the President's memorandum of April 29, 1994,
GovernmenttoGovernment Relations with Native American Tribal
Governments (59 FR 22951), Executive Order 13175, titled Consultation
and Coordination with Indian Tribal Governments (65 FR 67249), and the
Department of the Interior's manual on Departmental Responsibilities
for Indian Trust Resources, at 512 DM 2, we acknowledge our
responsibility to communicate meaningfully with recognized Federal
Tribes on a governmenttogovernment basis. In accordance with
Secretarial Order 3206 of June 5, 1997 (American Indian Tribal Rights,
FederalTribal Trust Responsibilities, and the Endangered Species Act),
we readily acknowledge our responsibilities to work directly with the
Tribes in developing programs for healthy ecosystems, to acknowledge
that Tribal lands are not subject to the same controls as Federal
public lands, to remain sensitive to Indian culture, and to make information available to Tribes. In fulfilling our trust
responsibilities for governmenttogovernment consultation with Tribes, we met with the Ute Mountain Ute Tribe regarding the process we would take to conduct a 12month status review of Astragalus schmolliae. As an outcome of our governmenttogovernment consultation, we recognize the sovereign right of the Ute Mountain Ute Tribe to manage the habitat for A. schmolliae on its tribal lands, and acknowledge that right in this 12month finding.
Previous Federal Actions
Federal action for Astragalus microcymbus and Astragalus schmolliae (then A. schmollae) began as a result of section 12 of the Act of 1973, as amended (16 U.S.C. 1531 et seq.), which directed the Secretary of the Smithsonian Institution to prepare a report on plants considered to be endangered, threatened, or extinct in the United States. This report, designated as House Document No. 9451, was presented to Congress on January 9, 1975. In that document, both species were designated as endangered (House Document 9451, pp. 5758). On July 1, 1975, the Service published a notice in the Federal Register (40 FR 27823, p. 27847) of its acceptance of the Smithsonian report as a petition within the context of section 4(c)(2) (now section 4(b)(3)) of the Act, and giving notice of its intention to review the status of the plant taxa therein.
As a result of that review, the Service published a proposed rule
on June 16, 1976, in the Federal Register (41 FR 24523, pp. 24543
24544) to determine endangered status pursuant to section 4 of the Act
for approximately 1,700 vascular plant taxa, including Astragalus
microcymbus and Astragalus schmolliae. The list of 1,700 plant taxa was
assembled on the basis of comments and data received by the Smithsonian
Institution, and the Service in response to House Document No. 94 51
and the July 1, 1975, Federal Register publication. General comments
received in response to the 1976 proposal are summarized in an April
26, 1978, Federal Register publication (43 FR 17909). In 1978,
amendments to the Act required that all proposals more than 2 years old
be withdrawn. A 1year grace period was given to proposals already more
than 2 years old. On December 10, 1979, the Service published a notice
in the Federal Register (44 FR 70796) withdrawing the portion of the
June 16, 1976, proposal that had not been made final which removed both
A. microcymbus and A. schmolliae from proposed status but retained both species as candidate plant
taxa that ``may qualify for listing under the Act.''
On December 15, 1980, the Service published a current list of those plant taxa native to the United States being considered for listing under the Act where Astragalus microcymbus and Astragalus schmolliae were identified as a category 2 taxon ``currently under review'' (45 FR 82479, pp. 8249082491). On November 28, 1983, A. schmolliae was moved to the ``taxa no longer under review'' list, and given a 3C rank indicating the species was proven to be more abundant or widespread than previously believed or not subjected to an identifiable threat (48 FR 53640, pp. 53641, 53662). The two species also were included as a category 2 species (A. schmolliae was not included as a 3C species despite the conclusions of the 1983 review) on September 27, 1985 (50 FR 39525, p. 3953339534), February 21, 1990 (55 FR 6184, p. 6190), and September 30, 1993 (58 FR 51144, pp. 5115151152). The category 2 species designation was defined as having enough information to indicate that listing the species as an endangered or threatened species was possibly appropriate.
On October 22, 1993, we received a petition dated October 19, 1993, from the Biodiversity Legal Foundation and Lee Dyer requesting that Astragalus microcymbus be listed as endangered under the Act, and that critical habitat be designated (Carlton et al. 1993, pp. 111). The petition included biological information regarding the species and several scientific articles in support of the petition. After careful consideration, we did not issue a 90day finding on the petition because the species was already included as a category 2 species (Spinks 1994, pp. 18).
On February 28, 1996, we proposed removing all category 2 species, including Astragalus microcymbus and Astragalus schmolliae, from our candidate species notice of review (61 FR 7596). This policy change was finalized on December 5, 1996, stating that the list was not needed because of other lists already maintained by other entities such as Federal and State agencies (61 FR 64481).
On July 30, 2007, we received a petition dated July 24, 2007, from Forest Guardians (now WildEarth Guardians) requesting that the Service: (1) Consider all full species in our Mountain Prairie Region ranked as G1 or G1G2 by the organization NatureServe, except those that are currently listed, proposed for listing, or candidates for listing; and (2) list each species as either endangered or threatened (Forest Guardians 2007, pp. 137). The petition incorporated all analyses, references, and documentation provided by NatureServe in its online database at http://www.natureserve.org/into the petition. We acknowledged the receipt of the petition in a letter to the Forest Guardians, dated August 24, 2007 (Slack 2007, p. 1). In that letter we stated that, based on preliminary review, we found no evidence to support an emergency listing for any of the species covered by the petition, and that we planned work on the petition in Fiscal Year (FY) 2008.
On March 19, 2008, WildEarth Guardians filed a complaint (1:08CV 472CKK) indicating that the Service failed to comply with its mandatory duty to make a preliminary 90day finding on their two multiple species petitionsone for the MountainPrairie Region, and one for the Southwest Region (WildEarth Guardians v. Kempthorne 2008, case 1:08CV472CKK). We subsequently published two 90day findings on January 6, 2009 (74 FR 419), and February 5, 2009 (74 FR 6122), identifying species for which we were then making negative 90day findings, and species for which we were still working on a determination. On March 13, 2009, the Service and WildEarth Guardians filed a stipulated settlement in the District of Columbia Court, agreeing that the Service would submit to the Federal Register a finding as to whether WildEarth Guardians' petition presents substantial information indicating that the petitioned action may be warranted for 38 MountainPrairie Region species by August 9, 2009 (WildEarth Guardians v. Salazar 2009, case 1:08CV472CKK).
On August 18, 2009, we published a partial 90day finding for the 38 MountainPrairie Region species, and found that the petition presented substantial information to indicate that listing of Astragalus microcymbus may be warranted based on threats from offroad vehicle use and drought; and that listing Astragalus schmolliae may be warranted based on threats from fire, nonnative species invasions, road construction, grazing, and drought; and went on to request further information from the public pertaining to both species (74 FR 41649, pp. 4165541656).
This notice constitutes the 12month finding on the July 24, 2007,
petition to list Astragalus microcymbus and Astragalus schmolliae as
threatened or endangered. Given that we are doing 12month findings for
38 species from this petition, and 67 species from the Southwest Region
multiple species petition (74 FR 419, January 6, 2009; 74 FR 66866,
December 16, 2009), and given the amount of resources that it takes to
complete a 12month finding, we are unable to complete 12month findings for all these species at this time.
Species InformationAstragalus Microcymbus
Species Description and Taxonomy
Astragalus microcymbus is a perennial forb (a plant that can live to more than 3 years of age and without grasslike, shrublike, or treelike vegetation) that dies back to the ground every year. The plant has slender stems that are sparsely branched with dark green pinnate leaves, with 915 leaflets arranged in an evenly spaced fashion along either side of a central axis. It is in the pea (Fabaceae) family. The spindly red to purple branches grow from 3060 centimeters (cm) (1224 inches (in.)) long to 30 cm (12 in.) high, and may trail along the ground, arch upwards, or stand upright, often being supported by neighboring shrubs. Flowers are small (0.5 cm (0.2 in.)), pealike, are found at the end of branches in clusters of 714 flowers, and have white petals that are tinged with purple. Fruits are boatshaped (hence the common name ``skiff'' and the Latin name microcymbus meaning ``small boat''), grow to less than 1 cm (0.4 in.), are triangular in crosssection, and hang abruptly downward from the branches. These characteristics, particularly the plant's diffuse branching, small whitepurple pealike flowers, and boatlike fruit pods distinguish this species from other Astragalus species in the area (description adapted from Peterson et al. 1981, pp. 57; Heil and Porter 1990, pp. 56; Isley 1998, p. 349).
Astragalus microcymbus was discovered in 1945 by Rupert Barneby roughly 6 kilometers (km) (4 miles (mi)) west of Gunnison, Colorado (Barneby 1949, pp. 499500). The species was not located again until 1955 by the Colorado botanical expert William Weber, who originally considered it to be nonnative because of its dissimilarity to the other numerous Astragalus species in the region (Barneby 1964, p. 193). Both of these early collections were from alongside Highway 50 near Gunnison, Colorado, at a location that has likely been destroyed. The plant was not located in its more intact and native habitat along South Beaver Creek until Joseph Barrell rediscovered the species in 1966 (Barrell 1969, p. 284; Colorado Natural Heritage Program (CNHP) 2010a, p. 14).
The Astragalus genus is large, with over 1,500 species that are
found on all continents except Antarctica and Australia, and with almost 600 species
in the United States, primarily in the West (Isley 1998, p. 149). The genus is divided into many sections. A. microcymbus is not similar in appearance to other Astragalus species in the region. Its presumed closest relative (from the Strigulosi section of Astragalus) is found in New Mexico, with other relatives extending southward, and being found mostly in Mexico (Barneby 1964, p. 193; Isley 1998, pp. 349350). The taxonomic status of A. microcymbus has not been disputed, although the monophyly (all members descended from a single common ancestor) of the Strigulosi section, and the placement of A. microcymbus within the section has been debated (Spellenberg 1974, pp. 394395; Heil and Porter 1990, pp. 1213). For the purposes of this finding, we consider A. microcymbus to represent a valid species and, therefore, a listable entity.
Biology and Life History
Astragalus microcymbus individuals live on average 2.23 years (with a range of 114 years). Most frequently, plants are alive for only 1 year (DePrengerLevin 2010a, pers. comm.). The plant flowers from mid to late May into July (Heil and Porter 1990, p. 18; Japuntich 2010a, pers. comm.). There are more flowering plants in early June than at any other time, and flowering then drops off or stops, with a second bloom occurring in July (Japuntich 2010a, pers. comm.). The earlier flowering plants are reportedly larger and more vinelike, and later flowering plants are much smaller sized and less vinelike (Japuntich 2010a, pers. comm.).
Little is known of how Astragalus microcymbus reproduces. For example, we do not know if the plant requires pollinators, or what pollinators are important for reproduction. A single plant that was caged in 1980 did not produce fruit (Heil and Porter 1990, p. 18). Although this was suggested as evidence that the plant may require pollinators, we believe that this speculation is premature, because the study was completed for only one individual. Studies of other Astragalus species have found some species to be totally reliant on pollinators, and others to be somewhat selfcompatible (able to produce seed without pollen from a different plant) but still relying on pollinators to some degree (Karron 1989, p. 337; Kaye 1999, p. 1254). Astragalus species with limited ranges are somewhat more self compatible than wider ranging relatives (Karron 1989, p. 337).
Several pollinators have been observed visiting Astragalus microcymbus, suggesting that pollinators may be important for reproduction, but little is known about what pollinators these are (with the exception of the two listed below) and which are most important. Two insects that regularly visit the flowers of A. microcymbus were collected in 1989 (Heil and Porter 1990, pp. 1819). One visitor was a small, black carpenter bee, Ceratina nanula that was collected from 3 sites (Heil and Porter 1990, pp. 1819), and is known from at least 11 western States (Discover Life 2009, p. 1). The other visitor was a small, yellow and brown satyr butterfly, Coenonympha ochracea ssp. ochracea, a species of the Rocky Mountains (Heil and Porter 1990, p. 19). We expect there are more pollinators than these two species, based on the limited number of observations and collections to date (Heil and Porter 1990, pp. 6, 1819; Sherwood 1994, p. 12), and because other Astragalus species are visited by many different pollinator species (Karron 1989, p. 322; Kaye 1999, pp. 1251 1252; Sugden 1985, p. 303).
Fruits of Astragalus microcymbus have been observed as early as lateMay, are always present by midJune, with peak fruiting occurring in midJuly, and all fruits falling off the plants by lateAugust (Heil and Porter 1990, p. 18). Fruit production varies greatly. For example, during a lifehistory study (discussed in further detail in Distribution and Abundance below), no fruits were counted in 2002, and 33,819 fruits were counted in 2008 (Denver Botanic Gardens [DBG] 2010a, p. 5). In the same 14year life history study (19952009), fruit production was high in only 3 years: 1995, 1997, and 2008 (DBG 2010a, p. 5). This type of synchronous seeding is sometimes referred to as mast seeding or mast years. Mast seedings may be a strategy to release enough seeds to feed seed predators, that are kept at lower numbers in years with little or no seed production, and still allow other seeds to germinate. Alternatively, it may be a product of increased pollination success (Crone and Lesica 2004, p. 1945). We are unsure of the conditions that lead to good seed and fruit set; overall annual precipitation does not explain the variability (DBG 2010a, p. 12).
Seed dispersal mechanisms have not been researched, but wind and rain are considered candidates (Heil and Porter 1990, p. 19). Seed dormancy, seed survival, and seed longevity in the soil are unknown. We do not know if specific cues (e.g., temperature, precipitation, or seed coat alterations) are needed to break seed dormancy. Seed bank studies for other Astragalus species indicate that the group generally possesses hard impermeable seed coats with a strong physical germination barrier. As a result, the seeds are generally longlived in the soil, and only a small percentage of seeds germinate each year (summarized in Morris et al. 2002, p. 30). Conversely, the DBG looked at soil cores taken from A. microcymbus monitoring sites and found only one seed. The authors concluded that A. microcymbus does not have an active seed bank (DBG 2010a, p. 6). More research is needed to better understand the seed bank's role in the life history of the species.
Astragalus microcymbus individuals may exhibit prolonged dormancy (remaining underground throughout a growing season). This trait may help a species better cope with drought or resourcelimiting conditions (Lesica and Steele 1994, pp. 209210). Between 6 and 90 percent of A. microcymbus individuals are dormant in a given year (DBG 2008, pp. 6, 13, 18). Dormancy varies significantly from year to year and between plots (DBG 2010a, p. 15). Of the individuals that exhibited prolonged dormancy, 54 percent remained dormant for 1 year, 10 percent were dormant for 2 years, with a decreasing percentage of individuals remaining dormant for each successively longer time period to 11 years (DBG 2008, p. 6). These numbers for prolonged dormancy are not definitive because researchers are unable to say with certainty if a plant returning to a spot where an individual was previously found is a new individual or an individual returning from prolonged dormancy (DePrengerLevin 2010a, pers. comm.).
Distribution and Abundance
We use several terms to discuss various sizes or groupings of
Astragalus microcymbus individuals: Element Occurrence, site, polygon,
point, and units. We consider the term Element Occurrence synonymous
with population and it is further defined below. Within a population,
various smaller ``sites'' have been hand drawn on maps between 1955 and
1994, and counted or tracked by site. To distinguish these older sites
from more recent Global Positioning System (GPS) mapping efforts, we
have used the term ``polygon'' (circles around clusters of individuals)
or ``point'' (points representing one or a few plants within the
immediate area) to describe data that was collected after 2003 with a
GPS unit. Finally, we have taken the polygons and points and created
``units'' on which to conduct our spatial analyses for this 12month finding. The
reasons for creating these units are described in further detail below.
The CNHP, the agency that tracks rare plant species in the State of Colorado, operates within the national NatureServe network and follows NatureServe protocols. NatureServe guidelines on designating Element Occurrences state they are to be designated to best represent individual populations, and are typically separated from each other by barriers to movement or dispersal (NatureServe 2002, p. 11). The CNHP assigns overall species ranks for rare plants within the State of Colorado. Astragalus microcymbus has a Global rank of G1 indicating the species is critically imperiled across its range, and a State rank of S1 indicating the species is critically imperiled within the State of Colorado (CNHP 2010b, pp. 1, 5). Since the species is known only from the State of Colorado, the State (S) and Global (G) ranks are the same.
Astragalus microcymbus has a very limited range. It is found in an
area roughly 5.6 km (3.5 mi) from east to west and 10 km (6 mi) from
north to south with a small, disjunct (widely separated) population
found 17 km (10.5 mi) to the southwest on Cebolla Creek (Figure 1). The
species is known primarily from Gunnison County with one site located
in Saguache County. The majority of sites and individuals are along
South Beaver Creek just southwest of Gunnison, Colorado. The species
occurs on lands managed by the Bureau of Land Management (BLM) Gunnison
Resource Area and adjacent private lands. Within known areas, A.
microcymbus has a spotty distribution, most likely linked to the
habitat being spotty on the landscape (Heil and Porter 1990, p. 16).
Using the highest counts across years and across all sites, we estimate
the total maximum historic population to be around 20,500 individuals
in 5 populations (Table 1; USFWS 2010a, pp. 14). However, more recent
counts indicate there are substantially fewer individuals than this
today (DBG 2010a, p. 7; BLM 2010, p. 3). We estimate A. microcymbus
occupied roughly 34 hectares (ha) (83 acres (ac)) in 2008 (BLM 2010,
pp. 810). In previous handdrawn estimates, A. microcymbus occupied roughly 131 ha (324 ac) (CNHP 2010a).
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Table 1Summary of Astragalus Microcymbus Populations (Element Occurrences) (USFWS 2010a, pp. 14) Number of sites Estimated number Population name Population No. (pre[dash]2004) of individuals Ownership Population rank Beaver Creek SE........................ 9 unknown 25 private................... Historic Henry.................................. 10 1 513 BLM....................... B Gold Basin Creek....................... 1 4 5,618 BLM....................... A South Beaver Creek..................... 2 39 14,317 BLM/private............... A Cebolla Creek.......................... none 1 unknown private................... C or D
Total.............................. ................. 45 20,473 Population rankings are categorized from A through D, with ``A'' ranked occurrences generally representing higher numbers of individuals and higher quality habitat, and ``D'' ranked occurrences generally representing lower numbers of individuals and lower quality (or degraded) habitat. A historic rank (H) indicates an occurrence that has not been visited for more than 20 years.
The CNHP defines an Element Occurrence of Astragalus microcymbus as any naturally occurring population that is separated by a sufficient distance or barrier from a neighboring population. More specifically, for A. microcymbus, a population is separated by 1.6 km (1 mi) or more across unsuitable habitat, or 3.2 km (2 mi) across apparently suitable habitat (CNHP 2010b, p. 1). Given this definition, the CNHP has four populations of A. microcymbus in its database (CNHP 2010b, p. 2). Of these four populations, one (likely the type locality) has not been relocated since 1985 and is considered historic. This site was partially searched (because of private land access) in 1994 and not relocated, although there have not been subsequent visits. It is considered historic because it has not been seen in 20 years. The site along Cebolla Creek has not yet been incorporated into the CNHP's database, but when incorporated will comprise a separate population based on the separation distances described above.
While individuals of the species have been lost, we are unaware of the loss of any Astragalus microcymbus populations, although we are unsure of the status of Beaver Creek Southeast population. Two A. microcymbus populations comprise multiple sites (Gold Basin Creek and South Beaver Creek), and a few of these sites may have been extirpated (locally extinct). Site revisits using more accurate GPS mapping equipment from 20042008 generally relocated historical sites but decreased the overall footprint of most sites into smaller polygons and points. We roughly estimate the new mapping of polygons and points generally represents a reduction of about 75 percent in aerial extent from the original sites. We are unsure if the reduction of the site footprints is because of an actual contraction in the size of the sites, if the sites moved over time, or if it is an artifact of mapping efforts using improved technology. We expect it may be a combination of all three. At three sites in the South Beaver Creek area, no plants were relocated despite several survey efforts; these sites may have been extirpated (USFWS 2010a; pp. 14; BLM 2010, pp. 710; DePrenger Levin 2010b, pers. comm.). In an extreme example, one site along South Beaver Creek (02303331975), was reduced from a larger 4ha (10ac) site to two small polygons that are 97 percent smaller than previously mapped (USFWS 2010a; pp. 14; BLM 2010, pp. 710).
The lumping of multiple sites into populations makes sense biologically because it generally represents areas where genetic exchange is possible (e.g., populations). However, past mapping efforts, site assessments, and count data have often been collected for smaller sites within a population (USFWS 2010a, pp. 14). The information gathered for these smaller sites is essential for tracking the status of the species but is somewhat problematic for an over arching analysis for several reasons. First, the confusion between numbering protocols makes it difficult to ensure that particular counts, habitat specifics, or threats discussed by different sources are from the same sites. Second, mapping methodologies have resulted in varying delineations, especially with the advent of GPS technology.
For our analyses in this 12month finding, we evaluated the sites,
polygons, and points within Astragalus microcymbus populations, and
created what we call units from which to conduct our analysis. We did
this for several reasons: (1) To simplify the problems associated with
tracking sites (i.e., different sources used different descriptors,
making it difficult to ensure that they were talking about the same
site); (2) to more broadly characterize and analyze the threats to the
species' habitat (we believe that sites, polygons, and points are too
fine scale); (3) because the polygons mapped in 2008 were on average
much smaller than the original handdrawn sites, we wanted to include
more of the potential or previously occupied habitat rather than
restricting our analysis to the 2008 mapped polygons; and (4) to
provide for a more detailed analysis than would occur if we were to
look at populations. To designate the units, we drew a perimeter around
all GPSderived polygons and points that were within 200 m (656 ft) of
one another, and then buffered each perimeter by an additional 100 m
(328 ft) (Figure 1; Table 2). This 100m (328ft) buffer was included
so that previously occupied habitat, as drawn on maps, fell within the
boundaries of these units. As a result of this exercise, all of the
sites within the Gold Basin Creek population were lumped. As shown in
Figure 1 above, this methodology divided the South Beaver Creek
population into six separate units. The Beaver Creek Southeast
population, located entirely on private land, is not included in our
units because we are unsure of its exact location and current existence.
Table 2Astragalus microcymbus Units for Our Spatial Analysis in This 12Month Finding (USFWS 2010a, pp. 14; 2010b, pp. 13). Est. number of Unit name Population No. individuals Acres Hectares Ownership Beaver Creek SE.................... 9..................... 25.................... Unknown.............. Unknown.............. private Henry.............................. 10.................... 513................... 10.8................. 4.4.................. BLM Gold Basin Creek................... 1..................... 5,618................. 315.1................ 127.5................ BLM [[Page 78520]]
South Beaver Creek 1............... 2..................... 6,136................. 918.5................ 371.7................ 70% BLM, 30% private South Beaver Creek 2............... 2..................... 3,667................. 684.5................ 277.0................ 68% BLM, 32% private South Beaver Creek 3............... 2..................... 2,464................. 163.6................ 66.2................. 96% BLM, 4% private South Beaver Creek 4............... 2..................... 778................... 24.1................. 9.75................. 70% BLM, 30% private South Beaver Creek 5............... 2..................... 1,232................. 38.3................. 15.5................. BLM South Beaver Creek 6............... 2..................... unknown............... 11.5................. 4.6.................. BLM Cebolla Creek...................... none.................. unknown............... 24.6................. 9.9.................. 6% BLM, 94% private
TOTAL.......................... ...................... 20,433*............... 2,190.8.............. 886.6................ 75% BLM, 25% private *Number is different from Table 1 above because the counts from two historical sites were excluded from the units.
Comprehensive surveys for Astragalus microcymbus were conducted in 1989 (BLM 1989a, pp. 131) and 1994 (Sherwood 1994, pp. 124). In 2008, the BLM conducted a comprehensive mapping effort without counts or population assessments (BLM 2010, p. 3). Several other efforts have counted individuals within certain sites (Japuntich 2010b, pers. comm.; DePrengerLevin 2010b, pers. comm.; 2010c, pers. comm.; 2010d, pers. comm.; USFWS 2010a, pp. 14). Count data from various sites are difficult to compare because there is no way of knowing if two observers, during different years, travelled across similar areas, and if the effort between the two counts were similar. In general, counts in 1994 were higher than 1989 (Sherwood 1994, p. 13; USFWS 2010a, pp. 14). Several other observers have subsequently returned to these sites and found that A. microcymbus numbers in 2004, 2005, 2007, and 2008 were much lower than those of 1994 and the 1980s, with many sites shrinking from thousands to hundreds of individuals (DBG 2010a, p. 7; BLM 2010, p. 3; USFWS 2010a, pp. 14). Site counts and estimates from the 1980s and 1990s often reported the number of A. microcymbus individuals as more than 500, and sometimes as more than 2,000 individuals. Most counts in the last 5 years have been far less, generally under 150 individuals with only 1 count over 400 individuals (USFWS 2010a, pp. 14).
In 1989, the BLM developed a protocol to provide longterm trend data for selected populations of Astragalus microcymbus (BLM 1989b, pp. 14). They applied the protocol in select locations in 1990, 1994, and 2008. The number of individuals between 1990 and 2008 was not statistically different, and both years had similar low annual precipitation (20 cm (8 in.)) compared to the average of 25 cm (10 in.) (USFWS 2010c, pp. 18; DBG 2010a, p. 12; Western Regional Climate Center [WRCC] 2010a, pp. 18). However, there were significantly more plants in 1994 (three to four times) than either 1990 or 2008. Precipitation was higher in 1994, roughly 10 cm (4 in.) more than in 1990 or 2008 (USFWS 2010c, pp. 18). We conclude that there are more aboveground plants in years with more precipitation.
The DBG has been monitoring Astragalus microcymbus annually since
1995 (Carpenter 1995, pp. 17; DBG 2003, pp. 123; 2007, pp. 116;
2008, pp. 120; 2010a, pp. 117). The DBG found a decline in the number
of A. microcymbus individuals from 19952009 (Figure 2), especially
from 19952002 (DBG 2010a, p. 5). When comparing the first year of
monitoring to the last, this decline is not statistically significant
because of a partial rebound in the last few years (DBG 2010a, pp. 5,
1011). This decline is apparent, although not significant, when
considering only aboveground individuals (p = 0.11) as well as when
combining aboveground individuals with dormant individuals (p = 0.19)
(Figure 2). Dormant individuals are unknown for the first and last
years of the study (1995 and 2008) because of problems associated with
finding dormant individuals in the first year, and because dormant
individuals cannot be distinguished from dead individuals in the last year.
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In conjunction with the lifehistory monitoring, the DBG conducted a population viability analysis using data from 19952006. They found that all monitored populations of Astragalus microcymbus were in rapid decline, and predicted that all populations will comprise 20 individuals or lesstheir definition of extinctby 2030 (DBG 2010a, p. 10). This analysis has not been updated incorporating more recent monitoring data. However, a preliminary review for a subsequent population viability analysis has found still declining trends but with a more gradual decline that would likely delay the predicted extinction date (DePrengerLevin 2010e, pers. comm.). Unfortunately, the population viability analysis including the 2007 and 2008 data has not been completed. The 2009 data cannot be used because of the problems associated with identifying dead or dormant individuals.
Astragalus microcymbus numbers are positively correlated with precipitation. In a statistical comparison, annual rainfall from August of the previous growing season to July of the current growing season positively influenced the number of A. microcymbus individuals, average maximum temperature in May and July negatively influenced the number of individuals, and rainfall in May and July positively influenced the number of individuals significantly (DBG 2010a, p. 6). In addition, rainfall in springtime months during the growing season was statistically correlated with more aboveground growth (DBG 2010a, p. 6).
Survey efforts, trend monitoring, lifehistory monitoring, and the corresponding population viability analysis all suggest that Astragalus microcymbus numbers are declining. In both of the more rigorous monitoring efforts, the decline seems to be correlated with precipitation. The drought in the early 2000s caused a huge decline in numbers, with a rebound in the later 2000s (DBG 2010a, p. 5). However, the very low survey numbers from this decade as compared to the 1980s and 1990s seem less correlated with precipitation (USFWS 2010a, pp. 1 4; WRCC 2010a, pp. 18). The reasons for these declines are not fully understood.
Astragalus microcymbus is found in the sagebrush steppe ecosystem at elevations of 2,3772,597 meters (m) (7,8008,520 feet (ft)). The plant is most commonly found on rocky or cobbly, moderate to steep (9 38 degrees) slopes of hills and draws (Heil and Porter 1990, p. 16), although there are some sites that are flat. Plants are generally found on southeast to southwest aspects, but are occasionally found on northern exposures (Heil and Porter 1990, p. 13). The average annual precipitation is around 25 cm (10 in.) a year, and is fairly consistently spread across the year, except for July and August when roughly twice the precipitation falls compared to the other months (WRCC 2010b, pp. 3, 8). Snow falls in the winter and remains on the ground from November/December through March/April (WRCC 2010a, pp. 3, 8). Winters are cold with an average daily high in January of 3 [deg]C (26.5 [deg]F) and an average daily low of 20 [deg]C (4.0 [deg]F). Summers are warmer. July is the hottest month with an average daily high of 27 [deg]C (81 [deg]F) and an average daily low of 6 [deg]C (44 [deg]F) (WRCC 2010b, pp. 38).
Astragalus microcymbus is found in open parklike landscapes
dominated by several sagebrush species, cacti, sparse grasses, and
other scattered shrubs. Shrubs are primarily represented by Artemisia
tridentata ssp. vaseyana (mountain big sagebrush), Artemisia tridentata
ssp. wyomingensis (Wyoming sagebrush), Artemisia frigida (fringed
sagebrush or prairie sagewort), and Artemisia nova (black sagebrush);
cacti include Yucca harrimaniae (Spanish bayonet), and Opuntia
polyacantha (plains pricklypear); grasses most commonly include
Achnatherum hymenoides (formerly Oryzopsis hymenoidesIndian
ricegrass), Elymus elymoides (formerly Sitanion hystrixsquirreltail),
Hesperostipa comata (formerly Stipa comataneedle and thread grass),
and Poa sp. (fescue); and the most common forbs include Cryptantha cinerea (James' Cryptantha)
and Penstemon teucrioides (germander beardtongue). Other shrubs and small trees found within A. microcymbus' habitat include Ribes cereum (wax currant), Symphoricarpos oreophilus (mountain snowberry), and Juniperus scopulorum (Rocky Mountain juniper).
Soils are well drained and vary from sandy to rocky, but are primarily a thin cobbleclay loam (Heil and Porter 1990, p. 13). The primary soils within Astragalus microcymbus units are stony rock land (46 percent), LuckyCheadle gravelly sandy loams with 545 percent slopes (39 percent), alluvial land (8 percent), and KezarCathedral gravelly sandy loams with 535 percent slopes (4 percent) (Natural Resource Conservation Service (NRCS) 2008; USFWS 2010b, pp. 1213). Geologically, A. microcymbus is associated with: (1) Felsic and hornblendic gneiss (metamorphic from igneous) substrates; (2) granitic (igneous) rocks of 1,700 millionyear age group; and (3) biotitic gneiss, schist, and migmatite (sedimentary) substrates with 52, 37, and 11 percent, respectively, in each geology (Knepper et al. 1999, pp. 21 22; USFWS 2010b, pp. 1011).
The areas where Astragalus microcymbus is found are generally distinct from surrounding habitats. They are more sparsely vegetated, drier than surrounding areas, more heavily occupied by cacti, and appear to have some specific soil properties as described above. This habitat is limited and patchily distributed on the landscape. Summary of Information Pertaining to the Five Factors
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR 424) set forth procedures for adding species to the Federal
Lists of Endangered and Threatened Wildlife and Plants. Under section
4(a)(1) of the Act, a species may be determined to be endangered or threatened based on any of the following five factors:
(A) The present or threatened destruction, modification, or curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or (E) Other natural or manmade factors affecting its continued existence.
In making this 12month finding, we evaluated the best scientific and commercial information available. Our evaluation of this information is presented below.
In considering what factors might constitute threats to a species,
we must look beyond the exposure of the species to a factor to evaluate
whether the species may respond to the factor in a way that causes
actual impacts to the species. If there is exposure to a factor and the
species responds negatively, the factor may be a threat and we attempt
to determine how significant a threat it is. The threat is significant
if it drives, or contributes to, the risk of extinction of the species
such that the species warrants listing as endangered or threatened as those terms are defined in the Act.
Factor A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range
The following potential factors that may affect the habitat or range of Astragalus microcymbus are discussed in this section, including: (1) Residential and urban development; (2) recreation, roads, and trails; (3) utility corridors; (4) nonnative invasive plants; (5) wildfire; (6) contour plowing and nonnative seedings; (7) livestock, deer and elk use of habitat; (8) mining, oil and gas leasing; (9) climate change; and (10) habitat fragmentation and degradation.
Residential and Urban Development
The majority of Astragalus microcymbus is located between 3.2 and 11 km (2 and 7 mi) of the town of Gunnison, Colorado, the largest town in Gunnison County (Figure 1). Rapid population growth in the rural Rocky Mountains, including the Gunnison area, is being driven by the availability of natural amenities, recreational opportunities, aesthetically desirable settings, grandiose viewscapes, and perceived remoteness (Riebsame 1996, pp. 396, 402; Theobald et al. 1996, p. 408; Gosnell and Travis 2005, pp. 192197; Mitchell et al. 2002, p. 6; Hansen et al. 2005, pp. 18991901). Gunnison County grew from 5,477 people in 1960 to 15,048 people in 2007, constituting a 300 percent increase in population in less than 50 years (CensusScope 2010, pp. 1 3; Colorado State Demography Office 2008, p. 1). The population of Gunnison County is predicted to more than double by 2050 to approximately 31,100 residents (Colorado Water Conservation Board 2009, p. 53).
Human population growth results in increased fragmentation of habitat (see Factor E below) (Theobald et al. 1996, pp. 410412), increased recreation and more roads (see Recreation, Roads, and Trails below) (Mitchell et al. 2002, pp. 56; Hansen et al. 2005, p. 1899), more utility corridors (see Utility Corridors below), more nonnative invasive plants (see Nonnative Invasive Plants below) (Hansen et al. 2005, p. 1896), and changes to ecological processes (Hansen et al. 2005, p. 1901). A recent but common pattern of population growth in the Gunnison area is ``exurban'' or ``ranchette'' development. These ranchettes consist of larger lots (generally more than 14 ha (35 ac)) each with an isolated large house. This type of development, because of its location outside of urban footprints, may have more impacts to ecosystems and biodiversity than urban or urban fringe development (Hansen et al. 2005, p. 1903). Much of this development occurs on steeper slopes, like those where Astragalus microcymbus is found, where views are better.
To the best of our knowledge, residential and urban development (aside from roads) has impacted only one Astragalus microcymbus unit: the Beaver Creek Southeast Unit. The original type locality along Highway 50 may have been lost to highway activities, and the nearby private lands where the plant was located in the late 1970s and early 1980s may have been lost to a gravel pit (Sherwood 1994, pp. 1819). No more than 30 plants were reported from this unit in any given year from 19551994 (USFWS 2010a, p. 1). Only two A. microcymbus sites are near buildings: There is a cabin near one of the larger A. microcymbus sites within the South Beaver Creek 1 Unit (BLM 1989a, p. 31), and there is a house within the Cebolla Creek Unit. We do not know if construction of either of these structures impacted A. microcymbus.
Twentyfive percent of the Astragalus microcymbus units are on private land, mostly along South Beaver Creek (Table 2). Five parcels of private land (with an additional parcel nearby) are currently within A. microcymbus units along South Beaver Creek ranging in size from 17 to 263 ha (43 to 650 ac), only one of which has any housing or agricultural developments. All of these parcels are used primarily for livestock ranching operations that have a much lower impact than urban or residential development.
These private land parcels bisect the South Beaver Creek 1 and
South Beaver Creek 2 Units, and clip portions of the South Beaver Creek
3 and South Beaver Creek 4 Units (USFWS 2010b, pp. 23). Roughly half
of the known Astragalus microcymbus individuals are within the South
Beaver Creek 1, 2, and 4 Units (Table 2), making them especially
important to the conservation of the species. These three units all have at least 30 percent of their area on private
lands (Table 2), more than the average across the units of 25 percent. Given their proximity to town, the rapid growth predicted for Gunnison County (Colorado Water Conservation Board 2009, p. 53), the lack of undeveloped parcels in desirable locations (Gunnison County 2005, p. 1), and their appealing views, these parcels are in a likely location for development and could be subdivided in the future. In addition, the Cebolla Creek Unit is located almost entirely on private land and is already partially developed.
Residential or urban development of these parcels would likely lead to the destruction of Astragalus microcymbus individuals, as well as fragment and alter the plants' habitat. In 2005, it was estimated that only 30 percent of the private lands in Gunnison County remained undeveloped (Gunnison County 2005, p. 1). Because only 30 percent of the private lands in Gunnison County remain undeveloped, and because the population of Gunnison County is expected to double by 2050, we conclude that the currently undeveloped private lands where A. microcymbus occurs are likely to be developed by 2050. The potential loss of up to 25 percent of the area (habitat) and even more of the individuals of A. microcymbus is a significant threat for a species with such limited numbers and a limited range (Table 2). This development also would fragment the habitat, potentially isolating small populations from one another leading to the further loss of individuals.
Currently, the impact of development on the species is relatively minor, consisting of the few examples provided above. Although 25 percent of Astragalus microcymbus individuals are on private lands with no protective mechanisms in place for the species, little development is currently occurring on these private lands. However, we believe that the threat of development to the species may increase in the foreseeable future based on future human population growth. Future development on these lands is likely, because of the rate of growth in the Gunnison area. Given that Gunnison County has seen a 300 percent increase in population in less than 50 years, that only 30 percent of the private lands remain undeveloped, and A. microcymbus' close proximity to the town of Gunnison, we expect that some of these private land parcels will be developed in the next several decades. Based on the population projections presented above, the foreseeable future for development is 40 years, as the population of Gunnison County is predicted to more than double by 2050. Based on the above information, we consider residential and urban development to be a threat to the species in the foreseeable future.
Recreation, Roads, and Trails
It is difficult to separate the effects of roads and trails from the effects of recreation where Astragalus microcymbus resides. Most forms of recreation within A. microcymbus' range include the use of roads and trails either as a form of recreation (e.g., vehicle use, mountain biking, or hiking) or as a way to access recreation areas (e.g., target shooting and rock climbing areas). For these reasons, we have chosen to address recreation, roads, and trails together in this section.
Roads cause habitat fragmentation because they create abrupt transitions in vegetation; add edge to adjacent patches; are sources of pollutants; and act as filters (allowing some species to cross but not others) and barriers (prohibiting movement) (Spellerberg 1998, pp. 317 333). Road networks contribute to exotic plant invasions via introduced road fill, vehicle transport of plant parts, and road maintenance activities (Forman and Alexander 1998, p. 210; Forman 2000, p. 32; Gelbard and Belnap 2003, p. 426). Many of these invasive species are not limited to roadsides, but also encroach into surrounding habitats (Forman and Alexander 1998, p. 210; Forman 2000, p. 33; Gelbard and Belnap 2003, p. 427).
Aside from the indirect effects discussed above, a road typically removes all vegetation from about 0.7 ha (1.7 ac) per 1.6 km (1 mi), while a single track trail removes all vegetation from about 0.1 ha (0.25 ac) per 1.6 km (1 mi) (BLM 2005a, p. 13). Roads also act as corridors that facilitate human interaction with species and increase the opportunities and the likelihood of travel across undisturbed (non road) areas. The recreational use of roads is on the rise. From 1991 to 2006, offhighway vehicle registrations increased 937 percent (from 11,744 to 109,994 within the state), with an average annual increase of 16 percent (Summit County Off Road Riders 2009, p. 1). Recreational activities within the Gunnison Basin are widespread, occur during all seasons of the year (especially summer and hunting season), and have expanded as more people move to the area or come to recreate (BLM 2009a, pp. 78). Motorized and mechanized use has been increasing within the Gunnison Basin and is expected to increase in the future based on increased population (USFS and BLM 2010, pp. 5, 9, 85, 124 125, 136, 158, 177, 204, 244, 254, 269, 278).
Because Astragalus microcymbus generally occurs on slopes, it is somewhat protected from the further development of large roads. And many of the existing roads, although not all, run immediately along the bottom or top of sites instead of through the middle of sites. However, these slopes appear to be the preferred location for dirt bike and mountain bike trails, especially those that were usercreated instead of formally designed. Many of the trails within the range of A. microcymbus are usercreated and run across or up through the slopes where the plant is found (USFWS 2010, pers. comm.). These usercreated trails, when redesigned, often require a series of switchbacks, which could increase the opportunity for impacts to the plant. Travel management (the allocation and utilization of motorized and nonmotorized use), and route designation and design, both within the Hartman Rocks Recreation Area and outside that area, are described in further detail below.
Except for the one disjunct population, all of the Astragalus microcymbus units are within 11 km (7 mi) of the town of Gunnison, the closest of which is 3.2 km (2 mi) away. This close proximity to an urban area makes the species more susceptible to recreational impacts than if it were located more remotely. The Hartman Rocks Recreation Area is a popular urban interface recreation area and contains roughly 40 percent of the A. microcymbus units (BLM 2005a, p. 3; USFWS 2010b, pp. 45). The Hartman Rocks Recreation Area is located between 3 and 10 km (2 and 6 mi) from the town of Gunnison on BLM lands (BLM 2005a, p. 3). The Hartman Rocks Recreation Area covers 3,380 ha (8,350 ac), but trails expand out onto adjacent lands. These lands also have A. microcymbus plants and habitat that are being impacted by these trails (BLM 2005a, p. 3).
We have no detailed information on how much use occurs, how this
use is increasing, or when the use is occurring in the Hartman Rocks
Recreation Area. In 2005, it was estimated that the Hartman Rocks
Recreation Area received 15,00020,000 user days each year (BLM 2005a,
p. 3). Recreation activities within the Hartman Rocks Recreation Area
include mountain biking, motorcycling, allterrain vehicle riding, 4
wheeling, rock climbing, camping, trail running, horseback riding,
cross country skiing, snowmobiling, dog sledding, hill parties, target
shooting, hunting, paintball, and more (BLM 2005a, p. 3). We have seen most of these activities
occurring adjacent to or within Astragalus microcymbus sites (USFWS 2010, pers. comm.).
The BLM's Hartman Rocks Recreation Management Plan closed two trails and rerouted one trail to protect Astragalus microcymbus (BLM 2005a, p. 18; Japuntich 2010c, pers. comm.). These closures were for trails that were directly impacting A. microcymbus individuals. The Aberdeen Loop trail goes very close to several A. microcymbus sites within the South Beaver Creek 1, South Beaver Creek 5, and South Beaver Creek 6 Units. To protect Gunnison sagegrouse broodrearing habitat, a reroute of this trail is planned in the next few years that will put the trail further from these A. microcymbus sites (Japuntich 2010d, pers. comm.). Many trails are open yearround in the Hartman Rocks Recreation Area, but with less use in the winter and early spring when trails are snow covered or muddy. Closures during A. microcymbus' growing season (likely late April through August) would benefit the species by reducing impacts to seedlings and plants, and by lessening disruptions to pollinators. The Aberdeen Loop trail that runs through the South Beaver Creek 1, South Beaver Creek 5, and South Beaver Creek 6 occupied A. microcymbus habitat is subject to seasonal closures for the Gunnison sage grouse from June 15 until August 31. This closure provides partial protection for A. microcymbus in the growing season.
The South Beaver Creek Area of Critical Environmental Concern (ACEC) (also a Colorado Natural Area) was designated in 1993 by the BLM with the intent of protecting and enhancing existing populations of Astragalus microcymbus (BLM 1993, pp. 2.18, 2.29; Colorado Natural Areas Program [CNAP] 1997, pp. 17). The South Beaver Creek ACEC is 1,847 ha (4,565 ac), and includes 60 percent of the A. microcymbus units rangewide (BLM 1993, p. 2.18; USFWS 2010b, pp. 89). Seventy percent of the South Beaver Creek ACEC is within the Hartman Rocks Recreation Area, although the South Beaver Creek ACEC was developed at least 8 years prior to the Hartman Rocks Recreation Area (BLM 2005a, p. 44). Because of its designation as a recreation area, the Hartman Rocks Recreation Area draws users to the area, which is in conflict with the ACEC's intent to protect and enhance A. microcymbus.
When the South Beaver Creek ACEC was designated, motorized vehicle traffic was limited to designated routes, whereas it had previously been open on all lands (BLM 1993, p. 2.30). Outside the South Beaver Creek ACEC, all lands within the range of Astragalus microcymbus remained open to motorized vehicle traffic. In 2001, mechanized travel, including mountain bikes, on all lands within the Gunnison Resource Area including the South Beaver Creek ACEC and the Hartman Rocks Recreation Area was limited to designated routes (U.S. Forest Service (USFS) and BLM 2001a, p. 3; 2001b, pp. 12; BLM 2005a, p. 14). This closure resulted in new protections for A. microcymbus from mountain bikes and vehicular use on BLM lands outside the South Beaver Creek ACEC, and from mountain bikes within the ACEC.
Enforcement of travel designations and trail closures is difficult given the large area of the BLM's Gunnison Resource Area and limited law enforcement personnel (USFS and BLM 2010, p. 259). Illegal trails are always an issue in wellused recreation areas (BLM 2010, p. 4). Furthermore, the open parklike habitat of Astragalus microcymbus makes it difficult to disguise trails that have been closed. Numerous undesignated trails running through A. microcymbus habitat are visible on satellite images (see below). Law enforcement with the Gunnison Resource Area is provided by the BLM's Montrose Area Office, which is located over 105 km (65 mi) away. Law enforcement within this area is intermittent, and tickets are rarely, if ever, issued for trespass use (USFS and BLM 2010, p. 259).
As an example, the Quarry Drop trail that runs through the South Beaver Creek 1 Unit was closed in 2005 with the Hartman Rocks Recreation Plan, because it ran directly through two Astragalus microcymbus sites (BLM 2010, p. 4). Although this trail is posted as closed, it was still in use during the summer of 2009, when rocks were placed to close the trail entrance (BLM 2010, p. 4). The Gunnison Trails group (a local nonprofit trailbuilding group) and the BLM have increased their efforts on finding illegal trails and closing them before they become more established. Continued pressure from the recreation community for new trail construction is likely, as well as trespass use (BLM 2010, p. 4). In an effort to control illegal use, the BLM has put up educational signs where roads enter the South Beaver Creek ACEC explaining what A. microcymbus is and why the species and its habitat are important to preserve (BLM 2010, p. 6). Trails that have been closed are planned to be rehabilitated where they meet open trails during the summer of 2011 in an attempt to ensure they will no longer be used (Japuntich 2010d, pers. comm.).
The BLM and the USFS finalized a joint Environmental Impact Statement for a Gunnison Basin Federal Lands Travel Management Plan that includes areas on BLM lands outside the Hartman Rocks Recreation Area (USFS and BLM 2010, pp. 1288). This plan builds upon the Gunnison Travel Interim Restrictions of 2001 by closing additional routes, mostly for resourcerelated reasons (USFS and BLM 2010, p. 1). Astragalus microcymbus is not considered in detail in this plan, nor does the plan designate roads be closed specifically to protect A. microcymbus (USFS and BLM 2010, pp. 47, 7879). None of the closures proposed in the plan will benefit A. microcymbus nor do they address routes within the Hartman Rocks Recreation Area.
We have found roads, trails, and gravel parking areas atop Astragalus microcymbus individuals and polygons (USFWS 2010, pers. comm.). These roads, trails, and parking areas have no vegetation. A. microcymbus individuals can be found along the margins of these roads, trails, and parking areas, sometimes with tire tracks atop (USFWS 2010, pers. comm.). Cheatgrass is spreading from the old road bed upslope and into the one site where invasion is occurring (USFWS 2010, pers. comm.). Trails sometimes are deeply incised and eroded (USFWS 2010, pers. comm.).
We conducted a spatial analysis overlaying the distribution of
Astragalus microcymbus units with designated routes within and near the
Hartman Rocks Recreation Area. We found 8.8 km (5.5 mi) of roads (3.5
km (2.3 mi)) and trails (5.3 km (3.2 mi)) overlap with A. microcymbus
units (Table 3) (BLM 2010; USFWS 2010b, pp. 1415). Through this
mapping effort, we found four of the polygons within the Gold Basin
Creek Unit are being directly impacted by these roads and trails (USFWS
2010b, p. 16). We also are aware of at least three other polygons that
are being directly impacted by roads and trails (USFWS 2010, pers.
comm.). Estimating that a road typically removes all vegetation from
about 0.7 ha (1.7 ac) per 1.6 km (1 mi) while a single track trail
removes all vegetation from about 0.1 ha (0.25 ac) per 1.6 km (1 mi)
(BLM 2005a, p. 13), designated roads directly impact 1.6 ha (3.9 ac)
and designated trails directly impact 0.3 ha (0.8 ac) of habitat within A. microcymbus units.
Table 3Roads, Trails, and Paths Within Astragalus microcymbus Units [Designated routes are those included in the BLM's geospatial layers, undesignated are those located using satellite imagery] Designated Undesignated Unit name Total km (mi) Roads km (mi) Trails km (mi) Roads km (mi) Trails km (mi) Paths km (mi) Henry................................................... 0.1 (0.06) .............. 0.1 (0.06) 0.1 (0.06) .............. 0.3 (0.2) Gold Basin Creek........................................ 2.2 (1.4) 1.4 (0.9) 0.1 (0.06) 0.4 (0.2) 1.3 (0.8) 5.4 (3.4) South Beaver Creek 1.................................... 1.2 (0.7) 3.5 (2.2) 6.3 (3.9) 3.4 (2.1) 1.6 (1.0) 16.0 (9.9) South Beaver Creek 2.................................... .............. .............. 2.4 (1.5) 0.3 (0.2) 3.6 (2.2) 6.3 (3.9) South Beaver Creek 3.................................... .............. .............. 0.7 (0.4) .............. .............. 0.7 (0.4) South Beaver Creek 4.................................... .............. .............. .............. .............. .............. .............. South Beaver Creek 5.................................... .............. 0.2 (0.1) .............. .............. .............. 0.2 (0.1) South Beaver Creek 6.................................... .............. 0.2 (0.1) .............. .............. .............. 0.2 (0.1) Cebolla Creek........................................... .............. .............. 0.6 (0.4) .............. .............. 0.6 (0.4)
Total (km).......................................... 3.5 (2.2) 5.3 (3.3) 10.2 (6.4) 4.2 (2.6) 6.5 (4.0) 29.7 (18.5)
While travel is officially limited to designated routes only on BLM lands, there are numerous roads, trails, and paths that are not designated, with some receiving regular use. Some of these roads have been closed, but their footprint remains. Some of these roads are on private lands along South Beaver Creek, but many are trails or old roads on BLM lands that are undesignated, that either show evidence of use or could be receiving use. We used the NRCS' 2005 National Agriculture Imagery Program satellite imagery to look for roads, trails, and paths in occupied Astragalus microcymbus units additional to those BLM roads and trails included in the analysis above. We designated roads, trails, and paths based on the width of the disturbance. Roads were the widest, trails were narrower, and paths were the narrowest. We found almost 21 km (13 mi) of additional roads, trails, and paths, including: 10.2 km (6.3 mi) of roads, 4.2 km (2.6 mi) of trails, 6.5 km (4.0 mi) of paths (Table 3) (USFWS 2010b, pp. 21 22). Using the BLM's estimates of direct impacts (BLM 2005a, p. 13), undesignated roads directly impact 4.4 ha (10.9 ac), undesignated trails directly impact 0.3 ha (0.8 ac), and undesignated paths directly impact less than 0.4 ha (1 ac) of A. microcymbus habitat. Because we were using satellite imagery, we cannot say for certain what the level of use is on the trails, or even say if they are still in use. Some of the paths may have been livestock trails. Livestock trails may receive more or less use than other trails, but the effects are likely similar.
All units except the South Beaver Creek 4 Unit have roads and trails. Designated and undesignated roads denude about 5.7 ha (14.1 ac), designated and undesignated trails denude about 0.6 ha (1.6 ac), and undesignated paths denude less than 0.4 ha (1 ac) within Astragalus microcymbus units, or less than 0.8 percent (Table 4). To estimate the indirect effects of roads and trails, we used a 20m (66ft) buffer on either side of roads and trails. This distance represents the area where invasive nonnative species are most likely to invade, pollinators may be impacted or disturbed by passing vehicles, offtrail use is most likely, and impacts from dust may occur. This distance results in a conservative estimate of impacts, as it is probably more accurate for trails than roads (summarized in DBG 2010b, p. 1). Using this buffer distance, we estimate that roughly 14.5 percent of A. microcymbus' total habitat may currently be impacted by roads and trails (Table 4) (USFWS 2010b, pp. 2325). We expect our 15percent estimate is low. For example, plumes of dust are known to travel hun
FOR FURTHER INFORMATION CONTACT
Al Pfister, Field Supervisor, Western
Colorado Ecological Services Office (see ADDRESSES); by telephone, 970 2432778; or by facsimile, 9702456933. Persons who use a
telecommunications device for the deaf (TDD), call the Federal Information Relay Service (FIRS) at 8008778339.