[Federal Register Volume 76, Number 196 (Tuesday, October 11, 2011)]
[Proposed Rules]
[Pages 62722-62740]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-25470]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R2-ES-2011-0081; MO92210-0-0008]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To List Amoreuxia gonzalezii, Astragalus hypoxylus, and
Erigeron piscaticus as Endangered or Threatened
AGENCY: Fish and Wildlife Service, Interior.
ACTION: Notice of 12-month petition finding.
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SUMMARY: We, the U.S. Fish and Wildlife Service (Service), announce a
12-month finding on a petition to list Amoreuxia gonzalezii (Santa Rita
yellowshow), Astragalus hypoxylus (Huachuca milk-vetch), and Erigeron
piscaticus (Fish Creek fleabane) as endangered or threatened with
critical habitat under the Endangered Species Act of 1973, as amended
(Act). After review of the best scientific and commercial information
available, we find that listing Amoreuxia gonzalezii, Astragalus
hypoxylus, and Erigeron piscaticus is not warranted at this time.
However, we ask the public to submit to us any new information that
becomes available concerning the threats to Amoreuxia gonzalezii,
Astragalus hypoxylus, and Erigeron piscaticus or their habitats at any
time.
DATES: The finding announced in this document was made on October 11,
2011.
ADDRESSES: This finding is available on the Internet at http://www.regulations.gov at Docket Number FWS-R2-ES-2011-0081. Supporting
documentation we used in preparing this finding is available for public
inspection, by appointment, during normal business hours by contacting
the U.S. Fish and Wildlife Service, Arizona Ecological Services Field
Office, 2321 W. Royal Palm Road, Suite 103, Phoenix, AZ 85021;
telephone (602) 242-0210; facsimile (602) 242-2513. If you use a
telecommunications device for the deaf (TDD), please call the Federal
Information Relay Service (FIRS) at (800) 877-8339. Please submit any
new information, comments, or questions concerning this finding to the
above street address.
FOR FURTHER INFORMATION CONTACT: Steve Spangle, Field Supervisor, U.S.
Fish and Wildlife Service, Arizona Ecological Services Field Office,
2321 W. Royal Palm Road, Suite 103, Phoenix, AZ 85021; telephone (602)
242-0210; facsimile (602) 242-2513. If you use a telecommunications
device for the deaf (TDD), please call the Federal Information Relay
Service (FIRS) at (800) 877-8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(B) of the Act (16 U.S.C. 1531 et seq.) requires
that, for any petition to revise the Federal Lists of Threatened and
Endangered Wildlife and Plants that contain substantial scientific or
commercial information indicating that listing a 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 endangered or threatened, and expeditious progress is being made to
add or remove qualified species from the Lists of Endangered and
Threatened Wildlife and Plants. Section 4(b)(3)(C) of the Act requires
that we treat a petition for which the requested action is found to be
warranted but precluded as though resubmitted on the date of such
finding, that is, requiring a subsequent finding to be made within 12
months. We must publish these 12-month findings in the Federal
Register.
Previous Federal Actions
Amoreuxia gonzalezii, Astragalus hypoxylus, and Erigeron piscaticus
were formerly Category 2 candidate species, which are taxa for which
information in our possession indicated that proposing to list was
possibly appropriate, but for which persuasive data on biological
[[Page 62723]]
vulnerability and threats were not available to support a proposed
listing rule (58 FR 51144; September 30, 1993). The designation of
Category 2 candidate species was discontinued in 1996; therefore, these
species are not currently considered candidates.
On June 25, 2007, we received a formal petition dated June 18,
2007, from Forest Guardians (now WildEarth Guardians), requesting that
we do the following: (1) Consider for listing all full species in our
Southwest Region ranked as G1 or G1G2 by the organization NatureServe,
except those that are currently listed, proposed for listing, or
candidates; and (2) list each species under the Act as either
endangered or threatened and designate critical habitat. The
petitioners presented two tables that collectively listed 475 species
for consideration and requested that the Service incorporate all
analyses, references, and documentation provided by NatureServe in its
online database http://www.natureserve.org/ into the petition. The
petition clearly identified itself as a petition and included the
appropriate identification information, as required in 50 CFR
424.14(a). We acknowledged the receipt of the petition in a letter to
WildEarth Guardians dated July 11, 2007.
On December 16, 2009, we made a 90-day finding (74 FR 66866) that
the petition presented substantial scientific information indicating
that listing 67 of the 475 species may be warranted; Amoreuxia
gonzalezii, Astragalus hypoxylus, and Erigeron piscaticus were in that
group of 67 species. For Amoreuxia gonzalezii, the petition listed
urban and mining development and herbivory as threats to the species
and its habitat, along with competition from nonnative species. For
Astragalus hypoxylus, the petition listed degradation of habitat from
livestock grazing and impacts from recreation, as well as indirect
effects to bees, which may be the primary pollinator of this species.
For Erigeron piscaticus, the petition listed recreational impacts, poor
watershed conditions, flooding, and small population size as threats to
the species and its habitat. The 90-day finding initiated a status
review for these three plants (74 FR 66866; December 16, 2009). This
notice constitutes the 12-month finding on the June 18, 2007, petition
to list Amoreuxia gonzalezii, Astragalus hypoxylus, and Erigeron
piscaticus as endangered or threatened.
Evaluation of the Status of Each of the Three Plant Species
Section 4 of the Act (16 U.S.C. 1533) and implementing regulations
(50 CFR part 424) set forth procedures for adding species to, removing
species from, or reclassifying species on the Federal Lists of
Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of
the Act, a species may be determined to be endangered or threatened
based on any of the following five factors:
(A) The present or threatened destruction, modification, or
curtailment of its habitat or range;
(B) Overutilization for commercial, recreational, scientific, or
educational purposes;
(C) Disease or predation;
(D) The inadequacy of existing regulatory mechanisms; or
(E) Other natural or manmade factors affecting its continued
existence.
In making these findings, information pertaining to each species in
relation to the five factors provided in section 4(a)(1) of the Act is
discussed below. In considering what factors might constitute threats
to a species, we must look beyond the exposure of the species to a
particular factor to evaluate whether the species may respond to the
factor in a way that causes actual impacts to the species. If there is
exposure to a factor and the species responds negatively, the factor
may be a threat, and during the status review, we attempt to determine
how significant a threat it is. The threat is significant if it drives,
or contributes to, the risk of extinction of the species such that the
species warrants listing as endangered or threatened as those terms are
defined by the Act. However, the identification of factors that could
impact a species negatively may not be sufficient to compel a finding
that the species warrants listing. The information must include
evidence sufficient to suggest that the potential threat has the
capacity (i.e., it should be of sufficient magnitude and extent) to
affect the species' status such that it meets the definition of
endangered or threatened under the Act.
Evaluation of the Status of Each of the Three Plant Species
For each of the three species, we provide a description of the
species and its life-history and habitat, an evaluation of threats for
that species, and our finding that the petitioned action is warranted
or not for that species.
Species Information for Amoreuxia gonzalezii
Species Description
Amoreuxia gonzalezii is an herbaceous perennial (plant living 3 or
more years) in the Bixaceae family (Lipstick tree). The plant has a
thickened starchy to woody rootstock, erect stems to 50 centimeters
(cm) (20 inches (in)) in height, and long-petioled (long-stalked)
leaves that are deeply parted into five to seven spathulate (spoon-
shaped) lobes (Poppendieck 1981, p. 24). The inflorescences (clusters
of flowers) are few-flowered terminal cymes (branched flower clusters)
with salmon- to yellow-colored flowers with maroon marks at the base of
the upper and lower petals (Hodgson 1994, p. 3). The densely silky hair
of the ovary is one of two main characteristics that separate this
species from its more common relative A. palmatifida (Hodgson 1994, p.
4). The second characteristic separating the two species is the mature
fruit. The capsule in A. gonzalezii is ellipsoid and the seeds
spherical; in A. palmatifida, the capsules are ovoid with reniform
(kidney-shaped) seeds (Hodgson 1993, p. 27). Recent molecular work by
Fulton (2011, pers. comm.) verifies that A. gonzalezii is a valid
taxon, and we consider the species a listable entity.
Habitat and Biology
Amoreuxia gonzalezii is the farthest north-occurring species within
this tropical and sub-tropical genus found primarily in South America
(the primary center of diversification), Central America, and Mexico
(Poppendieck 1981, p. 24). Northern Mexico is the secondary center of
diversification for the genus and contains the majority of documented
locations of A. gonzalezii (Hodgson 1994, p. 5). In Mexico, A.
gonzalezii is found in tropical areas in foothills thornscrub and
tropical deciduous forest. Rainfall amounts range from 28 cm per year
(11 in) near the coast (thornscrub) to 60 cm (24 in) in tropical
deciduous forest. Freezes are very uncommon, and the bulk of rainfall
occurs from July through mid-September. The plants in these vegetation
communities are rainfall sensitive; in other words, the shrubs and
trees leaf out only when the rains begin, and drop their leaves when
the rainy season ends, usually in October (Yetman and Van Devender
2002, pp. 9-12). Geology of collection sites varies from granitic, to
quartz, to shale with quartz nodules and intrusives (molten igneous
rock that is forced into cracks or between other layers of rocks). In
the state of Sonora in Mexico, A. gonzalezii has been collected from
the vicinity of [Aacute]lamos, Choquincahui, El Oasis, Guirocoba,
Magdalena, Moctezuma, Onavas, Santa Ana, T[oacute]nichi, and Yocogigua,
as well as the Curea-Guadalupe Tayopa area. In the state of Sinaloa in
Mexico, the plant was
[[Page 62724]]
described from near Choix in the north. The specimens were found on
both shallow and steep hill slopes at elevations from 160 to775 meters
(m) (525 to 2542 feet (ft)).
In the United States, Amoreuxia gonzalezii has been collected from
the Devil's Cashbox area in the Santa Rita Mountains and Thomas Canyon
in the Baboquivari Mountains (Southwest Environmental Information
Network 2011). Both locations are in southeastern Arizona. We believe
that the Arizona locations represent the northernmost distribution of
this species. The Santa Rita A. gonzalezii plants are on lands
administered by the Coronado National Forest, Nogales Ranger District.
The plants occur in the foothills at an elevation of 1,311 to 1,402 m
(4,300 to 4,599 ft) on steep limestone slopes and ridgetops. The
habitat is described as the transition zone between Upper Sonoran
desertscrub and grassland (NatureServe 2010). The collection from the
granitic Baboquivari Mountains was from the sandy bank of a small
drainage on private land at 1,280 to 1,371 m (4,198 to 4,497 ft)
elevation. This site was described as an oak woodland and grassland
(Southwest Environmental Information Network 2011).
Very little is known about the biology of this species. Amoreuxia
gonzalezii has a drought avoidance adaptation and only produces stems,
leaves, flowers, and fruits following monsoon rains; it remains dormant
under the ground the remainder of the year (Coronado National Forest
1991, p. 3). Flowering occurs from July through September; flowers
remain open only in the morning hours, closing by 11:00 a.m. (Hodgson
1994, p.7). The species is an obligate outcrosser (needs pollen from
another individual to successfully produce seed) and may be pollinated
by unknown species of bees (Hodgson 1994, p. 7). Fruits develop in late
July and August, maturing in September to mid-October (Hodgson 1994, p.
7). Both flower and fruit production is dependent on the quantity of
summer precipitation. Amoreuxia gonzalezii also reproduces vegetatively
(asexually) from thick, tuberous or woody roots (Hodgson 2001, p. 94).
In 1987 and 1988, staff from the Desert Botanical Garden (Garden)
collected 142 seeds from the Devil's Cashbox area as part of the Center
for Plant Conservation National Collection program for conserving rare
plants and their seeds. The Garden's purpose was to determine viability
of stored seed and increase the number of plants in their living
collection (Desert Botanical Garden 1991, p. 1). An additional 72 seeds
were collected by Garden staff from one population in Sonora, Mexico at
an unknown date prior to 1991. In greenhouse trials, the Garden had
variable low rates of success, from 0 to 43 percent, in germinating 4-
year-old seed stored both at room temperature and in a freezer
facility. Viability of the seed bank and germination success in the
wild is unknown, though Hodgson did report finding 10 seedlings in 1991
in the Devil's Cashbox area (Southwest Environmental Information
Network 2011). In a greenhouse experiment, 4 plants produced 7 fruits
with a total of 232 seeds (Hodgson 1994, p. 7). Assuming this may be
optimum fruiting potential given ample water and greenhouse care, the
small population sizes from known populations (4to 24 individuals) may
produce few seeds in typical years. There are no monitoring plots or
current research in any of the populations in Arizona and Mexico.
Abundance
There are virtually no population estimates for any locations in
Mexico, although Hodgson (1994, p. 7) reported that one population in
Mexico in 1988 had ``well over two dozen'' individuals. The information
is not much better for the Arizona populations. Population estimates
for the Santa Rita population ranged from 14 individuals in 1988
(Southwest Environmental Information Network, 2011), to 4 individuals
in 1989 (Hodgson 1989, p. 2), and 25 individuals in 1991 (Southwest
Environmental Information Network, 2011). Hodgson (1994, p. 7) reports
fewer than 24 individuals from 2 micro-populations in the Santa Rita
Mountains. There were an estimated six to eight individuals in the
Thomas Canyon population (Toolin 2011, pers. comm.) in the 1990s.
Thomas Canyon was surveyed in 2011 and 30 plants were found (M. Baker
2011, pers. comm.).
In summary, there is very little ecological information available
regarding Amoreuxia gonzalezii. The species is found in Mexico, and the
United States, where the Arizona locations seem to represent the
northernmost locations for this species. The best available scientific
information does not indicate that this species was more widespread or
that known populations have been extirpated. Both populations in
Arizona seem to support a few individuals that are widely scattered
over appropriate habitat. The species' growth is tied to the summer
rains (monsoon), and in the fall, the plants become dormant. It seems
likely that this species is more abundant in Mexico, and may be more
closely tied with the thornscrub and tropical deciduous forest plant
communities, which are more humid, and where many plant species grow in
response to summer rainfall.
Five-Factor Evaluation for Amoreuxia gonzalezii
In making this finding, information pertaining to Amoreuxia
gonzalezii in relation to the five factors provided in section 4(a)(1)
of the Act is discussed below.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Potential factors that may affect the habitat or range of Amoreuxia
gonzalezii are discussed in this section, including: (1) Nonnative,
invasive species; (2) fire; (3) development; (4) mining; (5) watershed
degradation; (6) drought; and (7) climate change.
Nonnative, Invasive Species
Throughout the Sonoran Desert ecosystem, invasions of the
introduced Pennisetum ciliare (buffelgrass), Bromus rubens (red brome),
Eragrostis lehmanniana (Lehmann lovegrass), Schismus barbatus
(Mediterranean grass), and Pennisetum setaceum (crimson fountaingrass)
have altered nutrient regimes; species composition and structure; and
fire frequency, duration, intensity, and magnitude (Brooks and Pyke
2001, p. 5). Although most of these species were intentionally
introduced as forage for livestock, erosion control, or as ornamentals,
each is now considered invasive and a threat to this ecosystem. Species
such as P. ciliare are expected to increase their range even with
continued and predicted drought events (Ward et al. 2006, p. 724). It
is generally thought that invasion by exotic annual grasses will
continue unchecked in the Sonoran Desert ecosystem in the future,
reducing native biodiversity through direct competition and alteration
of nutrient and disturbance regimes (Franklin and Molina-Freaner 2010,
p. 1671).
Although exotic grasses are reported to threaten Amoreuxia
gonzalezii (Hodgson 1989, p. 3), no exotic grasses were noted within
the Devil's Cashbox habitat during field surveys in May 2011 (Service
2011a, p. 1). We have reviewed the best available scientific
information on exotic plants in or near populations of A. gonzalezii in
Thomas Canyon and in Mexico. In order to verify the identification and
location of plants, specimens are collected, pressed and placed on
sheets that are stored in herbaria. The labels on herbarium sheets
often note associated plant species that
[[Page 62725]]
are found in association with the collected specimen. There are no
exotic species noted as associates on any of the 12 specimen herbarium
sheets located at the Arizona State University, University of Arizona,
or the Sonoran University Herbarium collections, nor were any exotics
noted in the Devil's Cashbox and Sonora A. gonzalezii habitat
descriptions in Hodgson 1994 (pp. 5-6). Therefore, the best available
information does not provide evidence that nonnative invasive species
are a threat to the continued existence of A. gonzalezii or are likely
to become so.
Fire
There has been no scientific study on the impacts of fire on
Amoreuxia gonzalezii. This species is present aboveground in July
through October, and is dormant the remainder of the year. Because
fires in Arizona usually burn in the premonsoon season (May-June), it
seems unlikely that fire would affect this species (Alford et al. 2005,
p. 453). In addition, the plant has a large starchy root, which is
protected underground. It is possible that the root would be protected
from surface fire, allowing the plant to resprout after fire. In
summary, given the limited available information about the effect of
fire on A. gonzalezii, we have determined that fire is not a threat to
the continued existence of A. gonzalezii, or is likely to become so.
Development
The Santa Rita Amoreuxia gonzalezii population is located below the
Smithsonian Fred Whipple Observatory, located on Mt. Hopkins. There is
a visitor center for the observatory located at the base of Mt.
Hopkins, and Hodgson (1989, p. 4) noted that during the construction of
the visitor center, disturbance came very close to some A. gonzalezii
plants on the Devil's Cashbox ridge, but none of the plants were harmed
during construction. Hodgson (1994, p. 9) noted that communication is
vital among researchers, land managers, and potential developers in
regards to development near populations of A. gonzalezii. Available
information does not indicate any other development planned for this
area, and the area is fairly remote. In addition, the population is on
National Forest land, where development is not likely to occur. There
is also no information indicating any development near the Thomas
canyon site, nor any development near Amoreuxia populations in Mexico.
We have evaluated and determined, on the basis of the best available
scientific and commercial data, that development is not a threat to the
continued existence of A. gonzalezii, nor is it likely to become so.
Mining
NatureServe (2010) reports mining as a threat to this species,
perhaps due to the proximity of two active mining claims to the south
of the Devil's Cashbox plants (Ahern 2011, pers. comm.). There are
currently no known direct impacts of active or proposed mines on any
known population of Amoreuxia gonzalezii in the United States; these
impacts are unknown for populations in Mexico. Hodgson (2001, p. 93)
notes that A. gonzalezii tubers were collected frequently by native
peoples from ``a graphite mine site'' in Mexico, implying no negative
impact on the plant from this particular mine. It is unknown if the
mine was active or inactive at the times of harvesting. In summary,
based upon our review of the best available information, we conclude
that mining is not a threat to the continued existence of A.
gonzalezii, nor is it likely to become so.
Watershed Degradation
Improper livestock grazing can lead to habitat degradation and
watershed degradation. Overgrazing removes the vegetative cover which
can lead to erosion. The Santa Rita population is located within the
Agua Caliente grazing allotment on the Nogales Ranger District.
Degradation of habitat due to livestock grazing was noted as a threat
by NatureServe (2010) to Amoreuxia gonzalezii, although this was not
evident in a 2011 visit to the Devil's Cashbox area (Service 2011a, p.
1). The area that was assessed during that visit had no signs of
livestock trailing, or sign of livestock. The Forest Service reports
that this allotment, comprised of one pasture, is permitted for a 110
cow-calf operation (Lockwood 2011, pers. comm.). The grazing season is
May to November, but only 40 cows are presently grazing due to drought
conditions (Lockwood 2011, pers. comm.). The ridges where the plants
are located are quite steep, and it is unlikely that cattle graze in
these locations. The status of livestock grazing with regard to the
Thomas Canyon population is unknown, and no information is available
regarding livestock grazing near Amoreuxia populations in Mexico. After
reviewing the best available scientific information, we have determined
that watershed degradation as a result of livestock grazing is not a
threat to the continued existence of this species, nor is it likely to
become so.
Drought
Amoreuxia gonzalezii is dependent upon monsoon rains both for
growth and the production of flowers and fruits (Hodgson 1989, p. 3).
Hodgson (2001, p. 94) states that, ``With little precipitation, few
fruits are produced from very depauperate plants.'' The Thomas Canyon
location experienced less than average monsoon precipitation in 27 of
49 recorded years (July to August, period of record for average was
1961-2010, Kit Peak Weather Station, WRCC 2011). Similarly, the Devil's
Cashbox area has had less than average monsoon precipitation during 33
of 63 recorded years (period of record for average was 1946-2010,
Tumacacori National Historic Park (NHP) Weather Station, WRCC 2011). In
both locations, monsoon patterns varied yearly, with periods of below-
average precipitation never exceeding 7 consecutive years (Tumacacori
NHP 1998-2004), thus giving A. gonzalezii periods of recovery.
The climate pattern in the vicinity of [Aacute]lamos at the
southern end of the Amoreuxia gonzalezii range in Sonora is very
similar to Arizona, with the [Aacute]lamos-El Veranito weather station
reporting below-average monsoon precipitation in 14 of 28 recorded
years (July to August, period of record for average was 1977-2009,
Comisi[oacute]n Nacional del Agua (CNA), 2011). At the near center of
A. gonzalezii's Sonora range, the Carbo Weather station reported below
average monsoon precipitation in 30 of 50 recorded years, 10 of which
were consecutive from 1960-1969 (July to August, period of record for
average was 1960-2009, CNA, 2011).
It is not known whether Amoreuxia gonzalezii is drought-tolerant,
but the observation that plants are still present in sites that have
experienced reduced summer precipitation leads us to conclude that the
species is at least adapted to drought conditions. A. gonzalezii has
fleshy underground tubers, which can store food and water, and that is
an adaptation for dealing with drought. The best available information
does not indicate that drought is a threat to the continued existence
of A. gonzalezii, and the plant may have some adaptations for dealing
with drought; therefore, we conclude that drought is not a threat to
this species, or is likely to become so.
Climate Change
``Climate'' refers to an area's long-term average weather
statistics (typically for at least 20- or 30-year periods), including
the mean and variation of surface variables such as temperature,
[[Page 62726]]
precipitation, and wind; ``climate change'' refers to a change in the
mean or variability of climate properties that persists for an extended
period (typically decades or longer), whether due to natural processes
or human activity (Intergovernmental Panel on Climate Change (IPCC)
2007a, p. 78). Although changes in climate occur continuously over
geological time, changes are now occurring at an accelerated rate. For
example, at continental, regional and ocean basin scales, recent
observed changes in long-term trends include: a substantial increase in
precipitation in eastern parts of North American and South America,
northern Europe, and northern and central Asia, and an increase in
intense tropical cyclone activity in the North Atlantic since about
1970 (IPCC 2007a, p. 30); and an increase in annual average temperature
of more than 2 [deg]F (1.1[deg]C) across the U.S. since 1960 (Global
Climate Change Impacts in the United States (GCCIUS) 2009, p. 27).
Examples of observed changes in the physical environment include: an
increase in global average sea level, and declines in mountain glaciers
and average snow cover in both the northern and southern hemispheres
(IPCC 2007a, p. 30); substantial and accelerating reductions in Arctic
sea-ice (e.g., Comiso et al. 2008, p. 1), and a variety of changes in
ecosystem processes, the distribution of species, and the timing of
seasonal events (e.g., GCCIUS 2009, pp. 79-88).
The IPCC used Atmosphere-Ocean General Circulation Models and
various greenhouse gas emissions scenarios to make projections of
climate change globally and for broad regions through the 21st century
(Meehl et al. 2007, p. 753; Randall et al. 2007, pp. 596-599), and
reported these projections using a framework for characterizing
certainty (Solomon et al. 2007, pp. 22-23). Examples include: (1) It is
virtually certain there will be warmer and more frequent hot days and
nights over most of the earth's land areas; (2) it is very likely there
will be increased frequency of warm spells and heat waves over most
land areas, and the frequency of heavy precipitation events will
increase over most areas; and (3) it is likely that increases will
occur in the incidence of extreme high sea level (excludes tsunamis),
intense tropical cyclone activity, and the area affected by droughts
(IPCC 2007b, p. 8, Table SPM.2). More recent analyses using a different
global model and comparing other emissions scenarios resulted in
similar projections of global temperature change across the different
approaches (Prinn et al. 2011, pp. 527, 529).
All models (not just those involving climate change) have some
uncertainty associated with projections due to assumptions used, data
available, and features of the models; with regard to climate change
this includes factors such as assumptions related to emissions
scenarios, internal climate variability and differences among models.
Despite this, however, under all global models and emissions scenarios,
the overall projected trajectory of surface air temperature is one of
increased warming compared to current conditions (Meehl et al. 2007, p.
762; Prinn et al. 2011, p. 527). Climate models, emissions scenarios,
and associated assumptions, data, and analytical techniques will
continue to be refined, as will interpretations of projections, as more
information becomes available. For instance, some changes in conditions
are occurring more rapidly than initially projected, such as melting of
Arctic sea ice (Comiso et al. 2008, p. 1; Polyak et al. 2010, p. 1797),
and since 2000, the observed emissions of greenhouse gases, which are a
key influence on climate change, have been occurring at the mid- to
higher levels of the various emissions scenarios developed in the late
1990s and used by the IPCC for making projections (e.g., Raupach et al.
2007, Figure 1, p. 10289; Manning et al. 2010, Figure 1, p. 377; Pielke
et al. 2008, entire). Also, the best scientific and commercial data
available indicates that average global surface air temperature is
increasing and several climate-related changes are occurring and will
continue for many decades even if emissions are stabilized soon (e.g.
Meehl et al. 2007, pp. 822-829; Church et al. 2010, pp. 411-412;
Gillett et al. 2011, entire).
Changes in climate can have a variety of direct and indirect
impacts on species, and can exacerbate the effects of other threats.
Rather than assessing ``climate change'' as a single threat in and of
itself, we examine the potential consequences to species and their
habitats that arise from changes in environmental conditions associated
with various aspects of climate change. For example, climate-related
changes to habitats, predator-prey relationships, disease and disease
vectors, or conditions that exceed the physiological tolerances of a
species, occurring individually or in combination, may affect the
status of a species. Vulnerability to climate change impacts is a
function of sensitivity to those changes, exposure to those changes,
and adaptive capacity (IPCC 2007, p. 89; Glick et al 2011, pp. 19-22).
As described above, in evaluating the status of a species, the Service
uses the best scientific and commercial data available, and this
includes consideration of direct and indirect effects of climate
change. As is the case with all potential threats, if a species is
currently affected or is expected to be affected by one or more
climate-related impacts, this does not necessarily mean the species is
an endangered or threatened species as defined under the Act. If a
species is listed as endangered or threatened, this knowledge regarding
its vulnerability to, and impacts from, climate-associated changes in
environmental conditions can be used to help devise appropriate
strategies for its recovery.
While projections from global climate model simulations are
informative and in some cases are the only or the best scientific
information available, various downscaling methods are being used to
provide higher-resolution projections that are more relevant to the
spatial scales used to assess impacts to a given species (see Glick et
al, 2011, pp. 58-61).
Regional landscapes can be examined by analyzing climate models
that operate at small spatial scales; however, this approach involves
some uncertainty. The uncertainty arises due to various factors related
to difficulty in applying climate modeling to a smaller scale or
unknown information, including regional weather patterns, local
physiographic conditions, and fine-scale weather factors. Also, climate
models do not model biological responses, such as life stages of
individual species, generation time of species, and species' reactions
to changing carbon dioxide levels not being included in the models.
Most climate models do not incorporate a variety of plant-related
factors that could be informative in determining how climate change
could affect plant species (e.g., effect of elevated carbon dioxide on
plant water-use efficiency, the physiological effects on species of
exceeding the assumed (modeled) bioclimatic limit, the life stage at
which the limit affects the species (seedling versus adult), the
lifespan of the species, and the movement of other organisms into the
species' range) (Shafer et al. 2001, p. 207).
For southern Arizona, the most current downscaled climate
projections are available with \1/8\ degree resolution (approximately
12 km x 12 km) from the Coupled Model Intercomparision Project (Maurer
et al. 2007, entire). A West-Wide Climate Risk Assessment (Bureau of
Reclamation 2011) has been completed, but the focus of this study
[[Page 62727]]
was downscaled surface water projections for major river systems in the
West. As such, it is less useful for predicting upland effects from
future climate change scenarios, although stream flow is highly
correlated with precipitation and temperature, which also affect upland
ecosystems. Downscaled climate projections represent a consensus of
multiple climate models, but climate models alone are not able to
account for the myriad of biological processes that may affect a
species that only inhabits a narrow range, as local effects may reduce
or amplify the large-scale patterns that are projected over the larger
spatial resolution of the global climate models (Ray et al. 2010, p.
24). In summary, global and regional climate models can play an
important role in characterizing general changes to climate, which is a
major determinant of species distributions, so that the potential
impacts on natural systems can be assessed (Shafer et al. 2001, p.
213). However, they are less able to assess local impacts to species
with a limited range, such as the three plants discussed in this
finding.
Climate change is likely to affect the long-term survival and
distribution of native species, such as Amoreuxia gonzalezii, through
changes in temperature and precipitation. Hot extremes, heat waves, and
heavy precipitation will increase in frequency, with the Southwest
experiencing the greatest temperature increase in the continental
United States (Karl et al. 2009, pp. 28, 129). In the southwestern
United States, average temperatures increased approximately 1.5 [deg]F
(0.8 [deg]C) compared to a 1960 to 1979 baseline (Karl et al. 2009, p.
129). By the end of this century, temperatures are expected to warm a
total of 4 to 10 [deg]F (2 to 5 [deg]C) in the Southwest (Karl et al.
2009, p. 129).
Annual mean precipitation levels are expected to decrease in
western North America and especially the southwestern States by
midcentury (IPCC 2007, p. 8; Seager et al. 2007, p. 1181). The levels
of aridity of recent drought conditions and perhaps those of the 1950s
drought years will become the new climatology for the southwestern
United States (Seager et al. 2007, p. 1181). As mentioned previously,
southern Arizona is currently experiencing drought conditions, and
there has been a decline in winter precipitation over the last 34
years.
Atmospheric levels of carbon dioxide are expected to double before
the end of the 21st century, which may increase the dominance of
invasive grasses leading to increased fire frequency and severity
across western North America (Brooks and Pyke 2002, p. 3; IPCC 2002, p.
32; Walther et al. 2002, p. 391). Elevated levels of carbon dioxide
lead to increased invasive annual plant biomass, invasive seed
production, and pest outbreaks (Smith et al. 2000, pp. 80-81; IPCC
2002, pp. 18, 32; Ziska et al. 2005, p. 1328) and will put additional
stressors on rare plants already suffering from the effects of elevated
temperatures and drought.
In summary, climate change is affecting and will affect temperature
and precipitation events in the future. We expect that Amoreuxia
gonzalezii may be negatively affected by climate change with respect to
drought or alteration in summer precipitation. However, we believe that
A. gonzalezii is adapted to arid conditions, and the species has
survived previous periods of low summer rainfall in Arizona. Although
we believe climate change will impact plants in the future, the best
available information does not allow us to determine the magnitude and
scope of the potential effects on a local scale to A. gonzalezii, and
therefore, we conclude that climate change is not a threat to the
continued existence of this species, nor is it likely to become so.
Summary of Factor A
In conclusion, based on our review of the best available scientific
and commercial information, we have determined that nonnative invasive
species, fire, development, mining, and watershed degradation are not
threats to Amoreuxia gonzalezii. Nonnative invasive species are not
present in or near A. gonzalezii populations; therefore, they are not a
threat to the species. The best available information does not indicate
that fire, development, mining, or watershed degradation are threats to
the species. Drought may influence the population structure of A.
gonzalezii, but we conclude that drought is not a threat to the species
because the species has some adaptations for living in arid
environments and has survived periods of reduced summer precipitation.
We acknowledge that climate change, particularly the predictions of
less frequent, but perhaps more intense, summer precipitation, and
increasing temperatures in the Southwest, will affect individuals
populations of A. gonzalezii. However, the species is adapted to arid
conditions, and therefore we have determined that climate change is not
a threat to A. gonzalezii. Thus, the present or threatened destruction,
modification, or curtailment of its habitat or range is not a threat to
A. gonzalezii.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Hodgson (2001, p. 91) notes that roots, young leaves, fruits, and
seeds of Amoreuxia gonzalezii are edible. She says that, historically,
the plant had been collected in great amounts and was ``once an
important food source to various southwestern people.'' For example,
the Onavas Pimas Tribe historically harvested this species frequently,
although more recently, harvest is only incidental (Hodgson 2001, p.
92). The tubers are collected and roasted by the Seri Indians on
Tiburon Island, and by residents of Baja California. Evidently, the
tubers of this species can be broken up and new plants will grow from
the tuber pieces. In 1959, the noted anthropologist Homer Aschmann
(Hodgson 2001, p. 94) observed with the similar and sympatric species
Amoreuxia palmatifida that ``when the larger aboriginal population
[native peoples of Mexico] exploited more regularly the flats where
they grow, a larger yield of roots may have been maintained,'' implying
that local peoples who relied on Amoreuxia for food may have enhanced
populations by disturbing the soil and cutting roots. He stated that
areas that were visited more regularly looked as if they had been
plowed; the more disturbance, the more A. palmatifida grew. Both A.
palmatifida and A. gonzalezii were historically, and continue to be,
used by native peoples in a similar fashion, although we are unaware of
this type of harvesting in Arizona. In summary, A. gonzalezii plants
and roots have been used historically in parts of Mexico. There is no
information regarding the current use of this species in Mexico, or its
use in Arizona. Therefore, based on our review of the best available
information, we have determined that collection of the plants or the
roots is not a threat to A. gonzalezii, or is likely to become so.
Amoreuxia gonzalezii is not a plant of horticultural interest.
There is no documentation of any instances where A. gonzalezii was
collected from the wild other than as voucher specimens to document
occurrences (http://ag.arizona.edu/herbarium) or seed collection for
the purposes of conserving the species. Therefore, based on the best
available information, we have determined that collection is not a
threat to the continued existence of the species, or is likely to
become so.
Factor C. Disease or Predation
There is no information indicating that disease affects Amoreuxia
[[Page 62728]]
gonzalezii. However, A. gonzalezii is very palatable to cattle and
other ungulates (Hodgson 2001, p. 94). While some of the known
locations in Arizona occur on steep limestone cliffs largely precluding
cattle herbivory, plants in other locations are more susceptible.
Hodgson (1989, p. 2) noted finding Amoreuxia plants in the Devil's
Cashbox area with inflorescences (flowers) eaten. She was unable to
ascertain if these plants were A. gonzalezii, or the more common A.
palmatifida because the plants had no fruit (Hodgson 1989, p. 2). She
also noted 13 missing plants from the Devil's Cashbox area just weeks
after a previous site visit in 1990 (Hodgson 1989, p. 7). It is unknown
how susceptible populations in Mexico are to grazing pressure. During a
1988 visit to a population of A. gonzalezii outside of Moctezuma,
Sonora, Hodgson (1989, p. 2) noted that most plants had been browsed or
grazed. Grazing precludes sexual reproduction and, if it occurs on a
frequent basis, may lead to reduced seed production (Hodgson 1994, p.
9). However, A. gonzalezii also reproduces asexually; hence, the
populations are not totally dependent on seed production for
reproduction (Hodgson 2001, p. 94). Our review of the best available
information did not produce any evidence that the long-term viability
of A. gonzalezii populations in Arizona and Mexico has been affected by
grazing, and therefore, we conclude that grazing is not a threat to
this species.
It has been suggested that javelinas (hoofed mammals in the peccary
family) dig up the roots of Amoreuxia gonzalezii and that this may
constitute a threat to the species (NatureServe 2010). The Service
(2011a, p. 1) saw no evidence of this during the 2011 site visit, and
there is no information available on how often javelina dig up the
plants, or on what the long-term effects are to the populations. In
addition, if the plants respond to digging by producing more plants,
javelinas rooting in the soil may promote asexual reproduction.
Therefore, after review of the best available information, we conclude
that javelina digging up the plants and eating the roots of A.
gonzalezii is not a threat to the species.
Based on the best available information, we have determined that
disease and predation are not threats to the continued existence of
Amoreuxia gonzalezii, nor are they likely to become so.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
Amoreuxia gonzalezii is not protected by Arizona Native Plant Law
(Arizona Revised Statutes, Chapter 7 1993, entire). It does not appear
under any of the law's four categories of protection, although
previously it was given consideration to be included for protection
within the ``Salvage Restricted Protected Native Plants'' (Hodgson
1994, p. 9), a level of protection that Hodgson considered inadequate.
It was, however, never placed on this list (Hodgson 2011, pers. comm.).
This means that the populations that occur on private land in Arizona
have no protections. However, regardless of any protection under the
Arizona Native Plant Law, our five-factor analysis suggests that A.
gonzalezii populations are not subject to negative impacts at such a
level that would place the species at risk. Evidence of this can be
found in the Thomas Canyon population, which is on private property,
and remains intact, as evidenced by surveys completed this year.
Although A. palmatifida and A. wrightii are on the list of protected
animals and plants for Mexico, A. gonzalezii is not listed and
therefore receives no management considerations within its Mexican
range (SEMARNAT 2008). Even so, we have determined that populations in
Mexico are not subject to negative impacts at a level that would place
the species overall at risk.
Amoreuxia gonzalezii is considered by the Forest Service to be a
``sensitive species'' in the Coronado National Forest. A sensitive
species is defined as one not yet warranting listing as endangered or
threatened, but which is sufficiently rare that its future survival is
of concern (Forest Service Manual (FSM) 2670). The management of
sensitive species is described in FSM 2670, and the management
objectives are to develop and implement management practices to ensure
that species do not become endangered or threatened because of Forest
Service actions; maintain viable populations of all native and desired
nonnative wildlife, fish, and plant species in habitats distributed
throughout their geographic range on National Forest System lands; and
develop and implement management objectives for populations or habitat
of sensitive species or both.
In addition, the Forest Service has to consider the effects of
their actions on the viability of sensitive species through the
National Environmental Policy Act (NEPA; 42 U.S.C. 4321 et. seq.)
process. As defined by Forest Service policy, actions must not result
in loss of species viability or create significant trends toward the
need for Federal listing. A. gonzalezii receives these protective
measures through NEPA on Coronado National Forest land.
In summary, Amoreuxia gonzalezii populations in the Coronado
National Forest are protected by their status as sensitive species. We
believe that the requirement to consider the species' long-term
viability in the NEPA planning process provides adequate protection for
the populations of A. gonzalezii in the Coronado National Forest. Any
one factor in our analysis may constitute a threat; however, it is the
combined analysis of all the potential threats to the species that
determine whether a species warrants listing as an endangered or
threatened species under the Act. In this case, there is no indication
of actions or potential threats to the species on private land or in
Mexico that rise to a level such that listing is warranted. As such, we
conclude that the best available information indicates that A.
gonzalezii is not threatened by inadequate existing regulatory
mechanisms.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Amoreuxia gonzalezii has been classified as the global rank of G1,
Critically Imperiled, by NatureServe (2010) due to the small number of
small populations globally, palatability to cattle, and threat of
exotic annual grasses. Even though there are only 2 occurrences in the
United States, there seem to be at least 12 occurrences in Mexico.
There have been no systematic surveys in Mexico, and very few
population estimates.
Information on a species' rarity is relevant to the conservation
status of a species. Generally speaking, a species that has a
geographically restricted range is likely to be more susceptible to
environmental threats (e.g., fire, flood, drought, human land use),
should they occur, than a species that is not rare, because one fire or
flood could affect a larger total percentage of the range of a rare
species than of a widespread species. However, there is no available
information in this case to evaluate whether any environmental threats
are currently acting upon this potentially rare species in a negative
way, or are reasonably likely to act on it in the future. The fact that
a rare species is potentially vulnerable to stochastic processes does
not necessarily mean that it is reasonably likely to experience, or
have its status affected by, a given
[[Page 62729]]
stochastic process within timescales that are meaningful under the Act.
A species that has always been rare, yet continues to survive,
could be well-equipped to continue to exist into the future. Many
naturally rare species have persisted for long periods within small
geographic areas, and many naturally rare species exhibit traits that
allow them to persist despite their small population sizes.
Consequently, the fact that a species is rare does not necessarily
indicate that it may be in danger of extinction in the foreseeable
future.
The best available information provides no evidence that effects
often associated with small populations that were not naturally rare,
such as inbreeding depression or genetic drift, may be occurring in A.
gonzalezii populations. There is also no evidence that potential
effects to the species or its habitat may be more significant than
historically present such that a naturally rare species, such as A.
gonzalezii, would be at risk. Therefore, we conclude that overall
rarity and small population size are not a threat to A. gonzalezii, nor
are they likely to become so.
Finding for Amoreuxia gonzalezii
As required by the Act, we evaluated the five factors in assessing
whether Amoreuxia gonzalezii is endangered or threatened throughout all
or a significant portion of its range. We examined the best scientific
and commercial information available regarding the past, present, and
future threats faced by A. gonzalezii. We reviewed the petition,
information available in our files, other available published and
unpublished information, and we consulted with recognized species
experts.
There are no obvious threats to Amoreuxia gonzalezii or its
habitat. The species has been used historically as a food source by
indigenous people, but we have no information that collection and use
of the plants and tubers are currently a threat to the species or
likely to become so. Long-term drought and reduced summer rainfall will
likely affect individual plants and populations. However, the plants
are tolerant of moderate disturbance, and the species is adapted to
arid condition, as evidenced by the plants' survival during recent
periods of reduced summer rainfall. Based on the limited information
available, we conclude that drought is not threat to this species or
likely to become so. Climate change will likely affect the status of A.
gonzalezii in the future; however, the limited information available
that can be applied at a local scale does not suggest that climate
change is likely to threaten the species. Regarding other factors
potentially affecting A. gonzalezii, including nonnative, invasive
species; fire; development; mining; and watershed degradation, the best
available scientific information provides no evidence indicating that
they are currently threatening the species or likely to do so in the
future. Similarly, there is no evidence that overutilization, disease,
or predation are affecting this species. In addition, we have
determined that small population size is also not a threat to the
species because the species appears to be naturally rare and there are
no potential threats acting on the species above historical levels.
Further, because we have determined there are no threats on the
species, and none likely, existing regulatory mechanisms are adequate.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the potential
threats are not of sufficient imminence, intensity, or magnitude to
indicate that Amoreuxia gonzalezii is in danger of extinction
(endangered) or likely to become endangered within the foreseeable
future (threatened), throughout all of its range.
Significant Portion of the Range
Having determined that Amoreuxia gonzalezii is not in danger of
extinction, or likely to become so, throughout all of its range, we
must next consider whether there are any significant portions of the
range where A. gonzalezii is in danger of extinction or is likely to
become endangered in the foreseeable future.
The Act defines an endangered species as one ``in danger of
extinction throughout all or a significant portion of its range,'' and
a threatened species as one ``likely to become an endangered species
within the foreseeable future throughout all or a significant portion
of its range.'' The term ``significant portion of its range'' is not
defined by the statute. For the purposes of this finding, a portion of
a species' range is ``significant'' if it is part of the current range
of the species, and it provides a crucial contribution to the
representation, resiliency, or redundancy of the species. For the
contribution to be crucial, it must be at a level such that, without
that portion, the species would be in danger of extinction. We also
considered the historical range of the species, and have determined
that the current range is no different from the historical range.
Therefore, there has been no loss of the historical range, and no
further analysis of the historical range is required.
In determining whether Amoreuxia gonzalezii is endangered or
threatened in a significant portion of its range, we considered status
first to determine if any threats or potential threats acting
individually or collectively endanger or threaten the species in a
portion of its current range. We evaluated the current range of A.
gonzalezii to determine if there is any apparent geographic
concentration of the primary stressors potentially affecting the
species including nonnative, invasive plants; fire; development;
mining; watershed degradation; and drought. We have analyzed the
stressors to the degree possible, and determined that they are
essentially uniform throughout the species' range. We also found the
stressors are not of sufficient imminence, intensity, magnitude, or
geographically concentrated such that it warrants evaluating whether a
portion of the range is significant under the Act. We do not find that
A. gonzalezii is in danger of extinction now, nor is likely to become
endangered within the foreseeable future, throughout all or a
significant portion of its range. Therefore, listing A. gonzalezii as
an endangered or threatened species under the Act is not warranted at
this time.
We request that you submit any new information concerning the
distribution and status of, or threats to, Amoreuxia gonzalezii to our
U.S. Fish and Wildlife Service Office (see ADDRESSES section) whenever
it becomes available. New information will help us monitor A.
gonzalezii and encourage its conservation. If an emergency situation
develops for A. gonzalezii, or any other species, we will act to
provide immediate protection.
Species Information for Astragalus hypoxylus
Species Description
Barneby (1964, pp. 1028-1029) and Warren et al. (1991, pp. 3-4)
describe Astragalus hypoxylus as an herbaceous perennial, in the
Fabaceae (Pea) family. The species forms a compact mat of stems that
typically lay flat against the ground, although the outer ends of the
stems may turn up. The mat can be up to 15 cm (6 in) in diameter. The
species forms a tap root that is dense and fibrous. The alternate
leaves are compound with 11 to 13 ovate leaflets that are each 2 to 4.5
millimeters (mm) (0.1 to 0.2 in) long. The leaflets are bicolored; the
undersides are gray with sparse tiny hairs; the tops of the leaflets
are yellowish-green, smooth, and
[[Page 62730]]
hairless. The leaflets have a distinct fold along the midrib.
The inflorescence is very compact and ball-shaped, approximately 1
cm (0.4 in) in diameter and 1 to 1.5 cm (0.4 to 0.6 in) long and looks
somewhat like clover flowers. The flowers are approximately 6 mm (0.2
in) long with petals that are whitish, with light purple tips. The
flower stalks are erect above the vegetative mat. Fruits are small,
oval pods 7 to 9 mm (0.3 to 0.35 in) long and 2 to 2.5 mm (0.1 to 0.16
in) diameter. The pods are yellowish at the base and purplish towards
the tip when ripe. The pods do not split open, but drop whole from the
plant (Warren et al. 1991, pp. 3-4).
Astragalus hypoxylus most closely resembles A. parvus (no common
name) and A. nothoxys (sheep milkvetch). Astragalus parvus is only
known from Mexico, but A. nothoxys may be found with A. hypoxylus
(Johnson et al. 1992, p. 3). There are field characteristics that
differentiate the two species. A. nothoxys has much longer flowering
stalks, and the inflorescence is spread out along the flowering stems,
unlike the compact, clover-like flowers of A. hypoxylus. The seed pods
of A. nothoxyus are longer, narrower, three-sided, and green when fully
ripe, while those of A. hypoxylus are oval and yellowish-purple when
ripe. There has never been any disagreement in the scientific
literature regarding the taxonomy of this species; thus we consider A.
hypoxylus to be a valid taxon and a listable entity.
Habitat and Biology
Levin (1987, pp. 170-171) described the habitat that supports
Astragalus hypoxylus as ``stony openings in pine-oak juniper woodland,
restricted to limestone derived soils.'' Van Devender (1986, pers.
comm.) noted the same type of habitat, on a south-to-southwest
exposure. Warren et al. (1991, p. 7) observed that A. hypoxylus is
found in open, rocky clearings in woodlands comprised of Quercus emoryi
(Emory oak), Q. oblongifolia (Mexican blue oak), Juniperus deppeana
(alligator juniper), and Pinus cembroides (Mexican pinyon). The ground
is characterized by loosely consolidated, gravelly soil composed of
limestone and weathered rock. The plants are found at an elevation of
approximately 1,676 m (5,500 ft) (Warren et al. 1991, p. 7). This
habitat type is referred to as oak-savannah and is relatively common in
the mountains of southeastern Arizona between elevations of 1,370 to
1,830 m (4,494 to 6,000 ft) (Brown 1982, p. 59).
Astragalus hypoxylus produces flowers in the spring (April-May),
with fruits maturing approximately 3 weeks after the onset of flowering
(Johnson et al. 1992, p. 5). Pollination studies on different species
of Astragalus (Karron 1988, p. 332; Sugden 1985, pp. 303-304; Green and
Bohart 1975, pp. 383-384; Geer et al. 1995, p. 23) reported that
several bee species in the genera Bombus, Osmia, and Anthophora were
the primary pollinators. However, there have been no studies on the
pollinators for A. hypoxylus.
The pods of Astragalus hypoxylus do not split open when ripe and
usually fall to the ground near the parent plant. However, the pods are
light and may be blown to other locations by the wind (Johnson et al.
1992, p. 6). Seedlings are often detected in open places away from the
parent plants; however, nothing is known regarding seed dispersal of
this species (Falk, 2011, pers. obs.).
Germination studies of Astragalus hypoxylus were carried out by the
Desert Botanical Garden (Garden) as part of the Center for Plant
Conservation National Collection program for conserving rare plants and
their germplasm. Seeds were collected from the Harshaw and Bear Canyon
populations in 1991 and 1992. During the seed collection trips, the
biologists noted that ``plants were frequent along disturbed areas
(erosion cuts, dirt roads)'' (Pritchett-Kozak and Ecker 1992, p. 20).
Two germination tests were done in 1992, with germination rates of 66
and 76 percent (Pritchett-Kozak and Ecker 1992, p. 20). Tests done in
1991 with fresh seed and previously frozen seed were used, and the
germination rates were high for both sets of seeds, indicating that
freezing does not interfere with seed viability. Germination took place
during an average daytime temperature range of 73 to 86 [deg]F (23 to
30 [deg]C) (Ecker 1991, p. 1). These warm daytime temperatures may
indicate that the seeds germinate in the summer, in response to summer
rainfall, rather than in the winter. Also, the seeds readily germinated
in August, indicating that there is no summer dormancy for these seeds
(Ecker 1991, p. 1). Currently, there are approximately 14,000 seeds in
frozen storage at the Garden and the National Seed Storage Lab in Ft.
Collins, Colorado (http://www.centerforplantconservation.org). These
seeds are available for re-introduction efforts or augmentation of
existing populations.
In 1993, plants produced from collected seed were initiating floral
buds in the greenhouse by February 20. These were plants that were
produced from previous seedling experiments. On March 16, the plants
were placed outside on the grounds of the Garden, underneath native
trees. The plants began flowering profusely by early April. Open
pollination (plants were left in the open and pollination occurred
naturally) was successful, and the plants were producing numerous
fruits by April 20. There was no indication of pollinators in the area.
Plants that had been previously left in the greenhouse had not produced
seed, probably due to a lack of pollinators in the greenhouse.
Controlled cross-pollination of two plants (two flowers per plant) was
conducted on April 13, which resulted in two fruits per plant
(Pritchett-Kozak 1993, p. 20). Earlier attempts at self-pollination
failed, but the technique (use of a small paintbrush to transfer the
pollen) may not have been optimal (Pritchett-Kozak and Ecker 1992, p.
21). The results of the open pollination and the controlled cross-
pollination experiment likely indicate that Astragalus hypoxylus is an
obligate outcrosser (Pritchett-Kozak 1993, p. 20).
In conclusion, there is not a great deal of information on the
biology and ecology of this species. The pollinators of the species are
unknown; it is surmised that the plants are obligate outcrossers, and
that pollination takes place in the field because fruit and seeds are
produced. It is not known how seed is dispersed. Based on the
germination experiments conducted by the Desert Botanical Garden, the
best available information suggests that plants germinate in response
to summer rainfall. Also, there is some anecdotal information that
these plants occupy disturbed areas and may be tolerant of moderate
disturbance.
Distribution, Abundance, and Trends
Astragalus hypoxylus was first collected by J. G. Lemmon in 1882 in
Cochise County, Arizona, at a location described as ``Mahoney's Ranch,
near Ft. Huachuca.'' (Johnson et al. 1992, p. 4). This site description
proved to be so vague that this area was never able to be located again
(Johnson et al. 1992, p. 4). The species was not detected again until
1986, when it was collected in the Patagonia Mountains, approximately
4.5 kilometers (km) (2.8 miles (mi)) south of Harshaw on the road to
Washington Camp, in the Coronado National Forest (Levin 1987, pp. 170-
171). Later in 1986, botanists visited this same location and counted
approximately 107 plants in the area, again noting that the plants were
``common in grassy openings in oak woodland on relatively steep slopes
with coarse sandy soils'' (Van Devender 1986, pers. comm.; Kennedy
1986, pers. comm.). In 1991, Malusa et al. (1992, p. 25) found two
additional populations in the Patagonia
[[Page 62731]]
Mountains, near the Harshaw site. Approximately 180 plants were found
in adjacent canyons. These populations are within a couple of miles of
the Harshaw site and, for the purposes of this finding, will be
referred to as the Harshaw2 populations.
In addition, many surveys were undertaken by staff at the Nature
Conservancy and other botanical contractors to the Coronado National
Forest, and populations of Astragalus hypoxylus were found in the
Huachuca Mountains in Scotia, Bear, and Sycamore canyons, and in
Collins Canyon in the Canelo Hills (Warren et al. 1989, p 30; Gori et
al. 1990, p. 36; Gori et al. 1991, p. 45; Fishbein and Warren 1994, pp.
6-7). Populations in Bear, Sycamore, and Scotia canyons are dispersed
over a wide area and composed of several sub-populations, but, for the
purposes of this finding, will be referred to as individual
populations. All of these locations are on the Sierra Vista Ranger
District of the Coronado National Forest. In addition, suitable habitat
on Ft. Huachuca and in Sonora, Mexico was searched, but plants were not
found (Warren et al. 1991, pp. 5-6; Johnson et al. 1992, pp. 4-5;
Warren and Reichenbacher 1991, p. 26; Fishbein and Warren 1994, pp. 6-
7; Malusa 1995, p. 1). Therefore, the current distribution encompasses
only plants that occur along Harshaw Road in the Patagonia Mountains,
in Bear, Scotia, and Sycamore canyons in the Huachuca Mountains, and in
Collins Canyon in the Canelo Hills.
The Nature Conservancy established monitoring plots for Astragalus
hypoxylus in several of the populations (Warren et al. 1991, p. 8). Two
plots were established to monitor growth, reproduction, and mortality
of individual plants in the Harshaw population. These plots were
established in 1988, but one plot was abandoned in 1989 because the
site was steep and the survey was causing damage to the plants within
the monitoring plot. The remaining plot was monitored annually, from
1989-1991 and in 1993. Another plot was established at the Bear Creek
population in 1989, and data were collected from this plot in the same
years as the Harshaw plot. All plots were monitored in late April or
May, when the plants flower and set fruit. Neither monitoring plot has
been evaluated since 1993. However, some occupied sites were visited in
1995, in 2010, and in 2011, and population estimates were made,
although no other data were collected in the monitoring plots. Table 1
presents population estimates for the known locations.
Table 1--Population Counts and Estimates for Astragalus Hypoxylus
------------------------------------------------------------------------
Estimated number of individuals
Population (year of discovery) (year)
------------------------------------------------------------------------
Harshaw (1986)......................... 100-200 (1986)
** plants in both monitoring plots..... 109 (1988) **
* plants in remaining monitoring plot.. 112 (1989) *
70 (1990) *
139 (1991) *
114 (1993) *
22 (2011)
Bear Canyon (1988)..................... 110 (1989) *
* plants in the monitoring plot........ 60 (1990) *
85 (1991) *
61 (1993) *
154 (1995) *
0 (2010) *
Bear Canyon (1990)..................... 50 (1990)
(plants found outside the monitoring 346 (1995)
plot and in other areas of Bear 100 (2010)
Canyon).
Scotia Canyon (1990)................... 600-700 (1990)
1058 (1995)
500-600 (2010)
Harshaw2 (1991)........................ 180 (1991)
0 (2011)
Sycamore Canyon (1993)................. 320 (1993)
70-80 (1994) (not all sub-
populations visited)
65-80 (1994) (not all sub-
populations visited)
12 (1995) (not all sub-
populations visited)
Canelo Hills (1993).................... No estimate given in 1993;
presence of ``small
population'' was noted.
------------------------------------------------------------------------
Based on the surveys and monitoring data, there have been some
declines in the numbers of individuals found in the monitoring plots
and in additional occupied locations. The Harshaw population appeared
relatively stable throughout the monitoring period, with some
fluctuations in the overall numbers. For the period 1991-1993,
survivorship was 40 percent, with 64 recruits in 1993, which
represented 56 percent of the population in the plot. It is unfortunate
that the Harshaw site as not visited again until May 2011 (Service
2011b, pp. 1-4). During this visit, 5 healthy plants, which had
flowered, were found in the cutbank of the road, and 14 additional
plants were found nearby, slightly north of the road. The area where
the original Harshaw monitoring plot was thought to have been was
searched thoroughly and only three plants were found. These plants were
very small compared to those near and in the cutbank of the road. The
entire site was described as very dry, and the native grasses
``crunched beneath our feet'' (Service 2011b, p. 2). It is possible
that the plants near the road were getting additional moisture due to
their downslope location and their proximity to the road. Additional
searches were conducted near the described locations for the Harshaw2
populations, but no plants were found. Given the 18-year gap in
monitoring or visiting this site, we are unable to determine the long-
term trend for this population.
The situation is similar for the Bear Canyon monitoring plot.
Overall numbers fluctuated, but as of 1995,
[[Page 62732]]
there were more plants in the plot than there had been when the plot
was established. Fifteen years passed before the next visit, which
occurred in October 2010 (Service 2010, p. 1). This is not the ideal
time of year for a visit, but the plants are usually visible if there
has been summer rainfall. In this case, based on the growth of the
perennial grasses in the surrounding area, it seemed as if there had
been summer precipitation (Falk 2011, pers. obs.). No plants were found
in the monitoring plot, but there were plants to the east and south of
the plot. The plants were widely scattered over the area. There was no
evidence of flowering or fruits.
Additional surveys were conducted that day (Service 2010, p. 1)
along Forest Service Road 61, near Sycamore Canyon. Plants were
scattered in several different locations adjacent to the road,
including some areas that had been recently disturbed by vehicle
traffic. The majority of the plants observed were healthy. Many of
these plants looked like juveniles produced during the summer of 2010.
The last site visited was Scotia Canyon (Service 2010, p. 1). Many
plants were observed below the uppermost pond on the former Peterson
ranch property (now part of the Coronado National Forest) and
immediately downslope of that. Some of the largest plants were in the
roadbed, associated with eroded portions of the road. The observations
of these plants growing in disturbed areas (road cuts and eroded banks)
may indicate that this species is adapted to and may tolerate moderate
disturbance. We were unable to determine long-term trends for these
populations based on inconsistent monitoring efforts.
Another type of disturbance to the plant's habitat is fire. There
is no information on the plant's adaptation to fire, but the habitat
where the species grows is subject to fire on a periodic basis (Kaib et
al. 1996, p. 261). The observation that Astragalus hypoxylus is
tolerant of moderate disturbance may indicate that the species is fire
adapted, and may need periodic fire to reduce competition from grasses
and remove overstory vegetation that may increase understory
competition and shading.
Some of the fluctuation in population size may be attributable to
variation in climate. During dry years, there was increased mortality
of plants, and larger plants died in association with consecutive dry
years (Johnson et al. 1992, p. 7). Recruitment and survival may also be
correlated with winter precipitation as evidenced by the number of
recruits that were counted in 1993 in the Bear Canyon plot; more than
72 percent of the individuals counted that year were seedlings (Falk
and Warren 1994, p. 36). Coincidentally, 1992 was an El Ni[ntilde]o
year, with above-average precipitation for southern Arizona.
There are some observations from the monitoring efforts that may
shed light on the ecology of this species. Population size and flower
production appear to fluctuate greatly from year to year. There seems
to be a correlation with winter rainfall. That is, when winter
precipitation is good, the plants are larger and they produce more
flowers and fruit (Warren et al. 1991, p. 9; Johnson et al. 1992, pp.
7-8). Astragalus hypoxylus has a taproot, and individual plants may be
dormant (no above-ground biomass visible) during dry years, but produce
growth again when there is rain (Falk 2011, pers. obs.). Consequently,
the reduction in numbers across almost all of the populations may be in
response to the on-going drought in southern Arizona. Winter rainfall
has been declining steadily for the last 34 years, and most noticeably
in the period from 1998 to the present (McPhee et al. 2004, p. 2).
Although the correlation between population size and climate is not a
formal test of this hypothesis, the sharp decline noted for most of
these populations may be the result of prolonged drought.
Five-Factor Evaluation for Astragalus hypoxylus
In making this finding, information pertaining to Astragalus
hypoxylus in relation to the five factors provided in section 4(a)(1)
of the Act is discussed below.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Potential factors that may affect the habitat or range of
Astragalus hypoxylus are discussed in this section, including: (1)
Recreation; (2) watershed degradation resulting from improper livestock
grazing; (3) nonnative invasive species; (4) fuel wood harvesting; (5)
fire; (6) road maintenance; (7) drought; and (8) climate change.
Recreation
All known populations of this species occur on the Sierra Vista
Ranger District, on the Coronado National Forest. There is no special
management for the populations on Forest Service lands. The populations
at Harshaw do not appear to be affected by any recreational activities
(Johnson et al. 1992, p. 12). There was no sign of recreational
activity or impacts during the 2011 site visit (Service 2011b, entire).
The same is true for the populations scattered along Forest Service
Road 61, near Sycamore Canyon and in Scotia Canyon. In 2010, neither of
these populations showed evidence of trampling or associated effects
from recreational activities.
The only population that has been identified as being impacted by
recreational activity has been the upper Bear Canyon population. This
population has been impacted by an informal parking lot near the
turnoff to Wakefield Camp, which allows for access to Bear Creek, and
is a very popular area for dispersed camping and hiking (Warren et al.
1991, p. 10; Gori et al. 1991, p. 45). In 2000, the Forest Service
blocked off the informal parking area, created a formal parking in a
less sensitive area, and restricted access to the Bear Creek riparian
area (Frederick 2011, pers. comm.). This site has not been evaluated to
determine if these changes reduced the impacts from recreational
activity on Astragalus hypoxylus. At any rate, this population is
relatively small (50 plants were estimated at the time of discovery in
1990) (Gori et al. 1991, p. 45) and represents less than 10 percent of
the current population. In conclusion, recreational impacts may have
affected only one of the sub-populations in the entire range of the
species, and corrective actions were taken to reduce the impacts.
Review of the best available scientific information revealed no further
evidence that recreation is negatively affecting other A. hypoxylus
populations; therefore, we determined that recreation is not a threat
to the continued existence of the species, nor is it likely to become
so.
Livestock Grazing
All of the Astragalus hypoxylus populations occur with Forest
Service grazing allotments. The Harshaw populations are within the
Bender allotment, and all of the other populations are located within
the Lone Mountain allotment. The following information is from the
Service's biological opinion on the Continuation of Livestock Grazing
on the Coronado National Forest (2-21-98-F-399-R1) and additional
details can be found in that document. The Bender allotment is 1,287
hectares (ha) (3,180 acres (ac)) and supports a 14-cow-and-calf
operation. Grazing is allowed year-round and there is only one pasture.
The allotment is reported to be in moderately good condition. The Lone
Mountain allotment is 15,435 ha (38,140 ac), divided into 27 pastures.
It supports a 1,346-cow-and-calf operation. The allotment is reported
to be on an
[[Page 62733]]
upward trend, with 75 percent of the allotment classified as being in
moderately high range condition. Both the Bender and Lone Mountain
allotments are reported to be in moderately high range condition, and
watershed degradation is not likely to be a problem in allotments that
are maintained in good to high range conditions.
The Coronado National Forest has a drought policy which directs
grazing permittees to work with the Forest when rainfall for the water
year (beginning October 1) is less than 75 percent of normal by March 1
and the long-range forecast is for less than normal precipitation. In
addition, critical habitat for Liliaeopsis schaffneriana var. recurva
(Huachuca water umbel) is within the Lone Mountain allotment. As such,
there are additional restrictions placed on the grazing practices in
this allotment to protect occupied areas and critical habitat. Several
areas within this allotment receive special protections, such as the
Peterson pasture, which contains Scotia, Sycamore and Bear canyons. The
pastures are grazed in winter (November-March) and only when winter
rains are sufficient to provide adequate water throughout the pasture
to encourage livestock dispersal away from the canyon bottom.
Utilization of upland browse is not permitted to exceed 35-45 percent.
These restrictions benefit Astragalus hypoxylus because they reduce
impacts from livestock grazing and limit use of the upland areas during
drought periods, when overgrazing and trampling of habitat are more
likely to occur.
There were a few observations of trampling on Astragalus hypoxylus
habitat in the Bear Creek population (Johnson et al. 1992, p. 12).
Warren et al. (1991, p. 10) notes that livestock grazing, although
present in the area, does not seem to pose a direct threat. Livestock
trampling may disturb the soil and disrupt seedling establishment.
Population visits in 2001 and 2011 (Service 2010, p. 1; Service 2011b,
p. 2) did not note the presence of livestock or trailing through the
populations.
Livestock have not been observed to eat Astragalus hypoxylus. Many
species of Astragalus contain poisonous compounds, known as nitro-
toxins, which are highly toxic to livestock (Williams and Barneby 1977,
p. 310). A. nothoxys, which sometimes grows near and in proximity to A.
hypoxylus populations, has been tested and does contain nitro-toxins
(Johnson et al. 1992, p. 3). Livestock have been observed to graze on
A. nothoxys, primarily when forage is lacking (Schmutz et. al. 1968,
pp. 26-27). The Forest Service has not indicated that this species has
caused any problems with livestock in the Forest. Any eradication
program to eliminate A. nothoxys could possibly harm adjacent A.
hypoxylus; however, there is no evidence of any efforts to eradicate A.
nothoxys. A. hypoxylus has not been tested for nitro-toxins, but many
species in the Leptocarpa section of Astragalus (A. hypoxylus is
classified in this section) contain these chemicals. At any rate, the
limited distribution of A. hypoxylus and the lack of observation of
cattle eating this plant indicates that the potential poisoning of
livestock is unlikely.
In summary, all populations of Astragalus hypoxylus occur in
grazing allotments. Those grazing allotments are being managed in ways
that promote healthy watershed and good range condition. The Lone
Mountain allotment has additional grazing practices that protect
riparian and upland habitat, resulting in improved watershed health,
which benefits upland species, including A. hypoxylus. The best
available information does not provide further evidence that livestock
grazing is negatively affecting populations of A. hypoxylus; therefore,
we have determined that livestock grazing is not a threat to the
continued existence of the species now, nor is it likely to become so.
Nonnative, Invasive Species
Nonnative species can have negative effects on the ecology of
native plant communities, as well as individual species (Brooks et al.
2004, p. 677; Alvarez and Cushman 2002, p. 1434; Mooney and Cleland
2001, p. 5446). However, there are no nonnative species that have been
detected in the populations of Astragalus hypoxylus. The only nonnative
grass that occurs in the vicinity of these populations is Eragrostis
lehmanniana (Lehmann lovegrass), but this grass has not been seen in
the monitoring plots or growing in the populations (Falk 2011, pers.
obs.). Eragrostis lehmanniana can form dense stands, increasing fine
fuels and fire danger (Anable et al. 1992, pp. 186-187), but there are
no continuous stands near any of the A. hypoxylus populations (Falk
2011, pers. obs.). The best available scientific information does not
suggest that nonnative invasive species are a threat to the continued
existence of A. hypoxylus, nor are they likely to become so.
Fuel Wood Harvesting
The Coronado National Forest did allow fuel wood harvesting in the
past near the known populations. It is unknown if these past activities
affected Astragalus hypoxylus populations. The collection of dead and
down wood was also allowed, with a permit, but this practice was
stopped in 1990 (Johnson et al. 1992, p. 12). Fuel wood harvesting is
no longer allowed in these areas (Frederick 2011, pers. comm.). The
best available information does not provide evidence that fuel wood
harvesting is currently affecting A. hypoxylus populations; therefore,
we have determined that fuel wood harvesting is not a threat to A.
hypoxylus, nor is it likely to become so.
Fire
As mentioned under Habitat and Biology, there is no information on
Astragalus hypoxylus and fire effects. The Forest Service's Fire
Effects Information System (http://www.fs.fed.us/database/feis/)
contains information on 7 species of Astragalus in the United States,
some of which are adapted to fire, and may even require fire, to
complete one of their life cycles (i.e., seeds need to be scarified by
fire before germinating). It is unknown if this is the case for A.
hypoxylus, but we hypothesize that this species may be tolerant of fire
because of the plant community where it grows and its tolerance for
moderate disturbance, including fire. Also, fire may be important in
maintaining habitat for A. hypoxylus by removing the overstory, thus
reducing competition and shading. In summary, given the limited
available information about the effect of fire on A. hypoxylus, we
determine that fire, or lack thereof, is most likely not a threat to
the continued existence of A. hypoxylus.
Road Maintenance
Portions of a few of the Astragalus hypoxylus populations are near
roads, and may be threatened by road maintenance activities, such as
blading (clearing and smoothing the road with a large piece of
equipment). However, the species appears to be tolerant of moderate
disturbance. In 2010, A. hypoxylus were observed near the road going
through Scotia Canyon. Portions of the road were well eroded, resulting
in rills (portions of the road that are washed out, forming small
gullies). There were 10-20 plants growing in the roadbed, on top of the
erosion rills. These were some of the largest and healthiest plants
observed in Scotia Canyon (Service 2010, p. 1). As mentioned
previously, in 2011, Service biologists found 19 plants at Harshaw that
were growing in the cutbank of the road, and these plants were larger
and
[[Page 62734]]
healthier than the plants upslope in the area of the monitoring plot
(Service 2011b, p. 1). This may indicate that plants are receiving
supplemental water due to the proximity of the road and concentrated
rainwater runoff, which may be why the plants are larger in the road
cuts.
Disturbed areas often afford the plants which grow on them reduced
competition for physical resources, such as water, and reduced
competition from other plants. However, these potential positive
effects of disturbance on Astragalus hypoxylus are unknown because
there have been no such studies. Regardless, there are only a few
portions of the populations that may be subject to Forest road
maintenance activities, and they represent a very small portion of the
total amount of occupied habitat. In addition, road maintenance
activities take place on a periodic basis, so the effects are likely to
be short-term and widely spaced over time. In conclusion, A. hypoxylus
seems to tolerate moderate disturbance, and the best available
information does not provide evidence that road maintenance activities
are a threat to the continued existence of the species, nor are they
likely to become so.
Drought
Data collected from the monitoring plots indicates that there is a
likely correlation between rainfall and the population dynamics of
Astragalus hypoxylus. As stated earlier, results from the Bear Canyon
monitoring effort indicate that seedling recruitment and establishment
was high when rainfall was high. We believe, based on data from the
monitoring plots, that winter rainfall affects the survivorship of the
seedlings. Summer rainfall may be important for germination, but
without winter rainfall, the seedlings would not survive. The
information provided in the following section was derived from data
accessed on the National Oceanic and Atmospheric Administration (NOAA)
National Climatic Data Center Web site (http://www.ncdc.noaa.gov).
Rainfall totals for Arizona (Division 7), which includes all of the A.
hypoxylus populations, for the months November through March, indicates
a severe decline over the past 34 years. Another way to illustrate the
decline is to use the Palmer Drought Severity Index (PDSI). The PDSI
``attempts to measure the duration and intensity of the long-term
drought-inducing circulation patterns.'' It is an index used to gauge
the severity of drought conditions by using a water balance equation to
track water supply and demand. When the historical PDSI values are
displayed for the years 1996-2011, 12 out of the 16 years were
classified as moderate to severe drought. In comparison, the PDSI
values for the same months during 1950-1960 (which is a well-documented
drought period in Arizona) classified 8 out of 10 years as moderate to
severe drought. There are significant differences between the two
drought periods; mainly that the current drought is much warmer than
the 1950s drought. On average, temperatures in the Four Corners region
of the Southwest were about 2 to 7 [deg]F (1 to 4 [deg]C) warmer than
in the 1950s (Weiss 2009, pp. 5920-5921). Drought with higher
temperatures creates tough growing conditions for plants because warmer
temperatures make the air drier, and drier air absorbs more moisture
from the soils, vegetation, and reservoirs. Thus, not only is there
less precipitation, but there is less moisture available in the soil
for plant growth.
It is difficult to predict how Astragalus hypoxylus populations
will fare with these drought conditions. The species apparently
persisted and survived the 1950s drought; however, this information is
of limited value as we evaluate potential conditions. The long-term
trend for these populations is unknown; it is possible that the
populations that are currently in decline will rebound when there is
sufficient moisture. Despite drought conditions, A. hypoxylus
populations in Scotia and Bear canyons seem stable, relative to the
previous population estimates presented in Table 1. The largely
circumstantial evidence available indicates that rainfall influences
population dynamics for A. hypoxylus, and drought likely contributes to
population declines. However, it is not known how the magnitude and
intensity of drought will affect the long-term status of this species.
Loss of individual plants, especially young plants, will likely occur
during drought years. Dry conditions will likely reduce seed
germination and survival. Population numbers of A. hypoxylus will
fluctuate as observed during the period of data collection in the
monitoring plots. However, this species is likely adapted to arid
conditions. The ability to remain dormant during dry periods, and
regrow when rainfall starts, is an adaptation for coping with arid
conditions. Further, A. hypoxylus populations survived the 1950s
drought, indicating the species has developed traits to survive during
dry periods. Therefore, based on the best available information, we
determine that drought is most likely not a threat to the continued
existence of A. hypoxylus.
Climate Change
No further specific information is available regarding the effects
of climate change on A. hypoxylus; therefore, please refer to the
``Climate Change'' discussion under Factor A. The Present or Threatened
Destruction, Modification, or Curtailment of Its Habitat or Range in
the Five-Factor Evaluation for Amoreuxia gonzalezii Section.
As discussed in the previous sections above, Astragalus hypoxylus
seedling establishment is likely correlated with rainfall; therefore,
reduced precipitation may reduce seedling establishment. Additionally,
the localized distribution of A. hypoxylus may make this species more
susceptible to landscape-level stochastic events, such as regional
drought. Despite these potential vulnerabilities, A. hypoxylus appears
well-adapted to a dry climate and tolerates moderate disturbance.
Plants growing in high-stress landscapes are adapted to stress, and
drought-adapted species may experience lower mortality during severe
droughts (Gitlin et al. 2006, pp. 1477, 1484).
In summary, climate change is affecting and will affect temperature
and precipitation events. We expect that Astragalus hypoxylus, like
other narrow endemics, may be negatively affected by drought associated
with climate change. However, A. hypoxylus appears to be adapted to
arid conditions, and has survived a previous long-term drought in the
1950s. Although climate change will likely affect plants in the future,
the limited available information does not suggest that the effect on
the status of the species will be significant. Therefore, based on the
best available information, we have determined that climate change is
not a threat to the continued existence of A. hypoxylus.
Summary of Factor A
In conclusion, based on the best available information, we have
determined that recreation; livestock grazing; nonnative, invasive
species; fuel wood harvesting; fire; road maintenance; or drought do
not threaten the continued existence of Astragalus hypoxylus.
Recreational impacts were associated with one population, and the
Forest Service has taken corrective action to reduce those effects. The
remaining populations are not affected by recreational activities. The
best available information does not provide evidence that livestock
grazing is a threat to this species. The plant is not eaten by
livestock, both of the grazing allotments are in good range condition,
and measures are in place to ensure
[[Page 62735]]
protection of upland and riparian areas. Nonnative, invasive species
are not present in or near A. hypoxylus populations; therefore, we have
determined that they are not a threat to the species. Fuel wood
harvesting is not allowed in the areas where A. hypoxylus is located;
therefore, we determined that this activity is not a threat to the
species. Given the limited available information, we have determined
that presence or absence of fire is most likely not a threat to the
species. Road maintenance activities may affect small portions of A.
hypoxylus populations, but we determined that these activities are not
a threat to the continued existence of the species because the effects
are short-term and the plants appear tolerant of moderate disturbance.
Drought influences the population structure of A. hypoxylus, but the
species has survived a previous long-term drought and appears to have
adaptations for dealing with drought, therefore, we have determined
that drought is not a threat to the continued existence of the species.
We acknowledge that climate change, particularly the predictions of
reduced precipitation and increasing temperatures in the Southwest,
will affect individuals and populations of A. hypoxylus. However, the
plant is adapted to arid conditions, and the limited available that can
be applied at a local scale does not suggest that climate change is
likely to threaten A. hypoxylus. Thus, the present or threatened
destruction, modification, or curtailment of its habitat or range is
not a threat to the continued existence of A. hypoxylus, nor is it
likely to become so.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Astragalus hypoxylus is not a plant of horticultural interest.
There is no evidence of any instances where A. hypoxylus was collected
from the wild other than as voucher specimens to document occurrences
(http://ag.arizona.edu/herbarium) or seed collection for the purposes
of banking seed for future conservation efforts. Therefore, we have
determined that overutilization is not a threat to the continued
existence of the species, nor is it likely to become so.
Factor C. Disease or Predation
There is no information indicating that disease affects Astragalus
hypoxylus. There are no observations or evidence that A. hypoxylus is
browsed by livestock (see Factor A, Livestock grazing). Data were
collected on A. hypoxylus seed predation by small wasps in 1988, but it
is unknown how this predation affected the A. hypoxylus population or
how often seed predation occurs (Johnson et al. 1992, p. 13). Based on
the best available information, we have determined that A. hypoxylus is
not threatened by disease or predation, nor is it likely to become so.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
The Act requires us to examine the adequacy of existing regulatory
mechanisms with respect to threats that may place Astragalus hypoxylus
in danger of extinction or likely to become so in the future. Existing
regulatory mechanisms that could have an effect on potential threats to
A. hypoxylus include (1) Local land use laws, processes, and
ordinances; (2) State laws and regulations; and (3) Federal laws and
regulations. A. hypoxylus occurs entirely on Federal land under the
jurisdiction of the Coronado National Forest; therefore, the discussion
below focuses on Federal laws.
Astragalus hypoxylus is listed as a sensitive species in the
Coronado National Forest. The management of sensitive species is
described in Forest Service Manual (FSM) 2670, and the management
objectives are to develop and implement management practices to ensure
that species do not become endangered or threatened because of Forest
Service actions; maintain viable populations of all native and desired
nonnative wildlife, fish, and plant species in habitats distributed
throughout their geographic range on National Forest System lands; and
develop and implement management objectives for populations or habitat
of sensitive species or both. In addition, the Forest has to consider
the effects of their actions on the viability of sensitive species
through the NEPA process. As defined by Forest Service policy, actions
must not result in loss of species viability or create significant
trends toward the need for Federal listing. A. hypoxylus receives these
protective measures in the Coronado National Forest, and the
designation has resulted in measures to reduce impacts from recreation
on the Bear Canyon A. hypoxylus population, and the consideration of
the species' needs in the NEPA planning process for the Bender and Lone
Mountain grazing allotments.
Summary of Factor D
We examined the existing regulatory mechanisms that protect
Astragalus hypoxylus. We have determined that the Forest Service
sensitive species designation adequately protects A. hypoxylus and its
habitat, and, thus, there is no evidence of impacts to A. hypoxylus
from inadequate existing regulatory mechanisms. We conclude that the
best available information indicates that A. hypoxylus is not
threatened by inadequate existing regulatory mechanisms.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
A threat identified by the petition was indirect effects to
pollinators, mainly bees. Johnson et al. (1992, p. 13) noted that the
use of pesticides to control insects, such as grasshoppers, may be
harmful to bees. The Coronado National Forest has not sprayed
pesticides for grasshopper control, and has no plans to do so. As
mentioned previously, the pollinators for Astragalus hypoxylus have not
been identified. As such, there is no evidence of activities that may
harm the potential pollinators of this species; therefore, we have
determined that the loss of pollinators from pesticide spraying is not
a threat to the species.
We are not aware of any other potential threats related to this
factor, such as small population size and overall rarity. Therefore, we
find that Astragalus hypoxylus is not threatened by small population
size and overall rarity, or is likely to become so.
Finding for Astragalus hypoxylus
As required by the Act, we evaluated the five factors in assessing
whether Astragalus hypoxylus is endangered or threatened throughout all
or a significant portion of its range. We examined the best scientific
and commercial information available regarding the past, present, and
future threats faced by A. hypoxylus. We reviewed the petition,
information available in our files, other available published and
unpublished information, and we consulted with recognized plant experts
and Forest Service biologists.
Astragalus hypoxylus populations are primarily affected by drought;
however, we determined that drought is not a threat to this species.
The plants are tolerant of moderate disturbance, and are adapted to
arid conditions, as evidenced by their survival during the 1950s
drought. Climate change will likely impact the status of A. hypoxylus
in the future; however, the limited available information suggests that
climate change will not threaten the continued existence of the
species. Other factors potentially affecting A. hypoxylus--including
recreation;
[[Page 62736]]
livestock grazing; nonnative, invasive species; fuel wood harvesting;
fire; and effects to potential pollinators--are either limited in
scope, or available evidence is lacking to indicate that they adversely
impact the species. There is no evidence that overutilization, disease,
or predation is affecting this species. In addition, we find that the
existing regulatory mechanisms are not a threat to the species.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the threats
are not of sufficient imminence, intensity, or magnitude to indicate
that Astragalus hypoxylus is in danger of extinction (endangered), or
likely to become endangered within the foreseeable future (threatened),
throughout all of its range.
Significant Portion of the Range
Having determined that Astragalus hypoxylus is not in danger of
extinction, or likely to become so, throughout all of its range, we
must next consider whether there are any significant portions of the
range where A. hypoxylus is in danger of extinction or is likely to
become endangered in the foreseeable future. We also considered the
historical range of the species, and have determined that the current
range is no different from the historical range. Therefore, there has
been no loss of the historical range, and no further analysis of the
historical range is required.
The Act defines an endangered species as one ``in danger of
extinction throughout all or a significant portion of its range,'' and
a threatened species as one ``likely to become an endangered species
within the foreseeable future throughout all or a significant portion
of its range.'' The term ``significant portion of its range'' is not
defined by the statute. For the purposes of this finding, a portion of
a species' range is ``significant'' if it is part of the current range
of the species, and it provides a crucial contribution to the
representation, resiliency, or redundancy of the species. For the
contribution to be crucial it must be at a level such that, without
that portion, the species would be in danger of extinction.
In determining whether Astragalus hypoxylus is endangered or
threatened in a significant portion of its range, we considered status
first to determine if any threats or potential threats acting
individually or collectively threaten or endanger the species in a
portion of its range. We evaluated the current range of A. hypoxylus to
determine if there is any apparent geographic concentration of the
primary stressors potentially affecting the species including
recreation; livestock grazing; nonnative, invasive plants; fuel wood
harvesting; fire; road maintenance; and drought. We have analyzed the
stressors to the degree possible, and determined that they are
essentially uniform throughout the species' range. We also found the
stressors are not of sufficient imminence, intensity, magnitude, or
geographically concentrated such that it warrants evaluating whether a
portion of the range is significant under the Act. We do not find that
A. hypoxylus is in danger of extinction now, nor is likely to become
endangered within the foreseeable future, throughout all or a
significant portion of its range. Therefore, listing A. hypoxylus as an
endangered or threatened species under the Act is not warranted at this
time.
We request that you submit any new information concerning the
distribution and status of, or threats to, Astragalus hypoxylus to our
U.S. Fish and Wildlife Service Office (see ADDRESSES section) whenever
it becomes available. New information will help us monitor A. hypoxylus
and encourage its conservation. If an emergency situation develops for
A. hypoxylus, or any other species, we will act to provide immediate
protection.
Species Information for Erigeron piscaticus
Species Description
Erigeron piscaticus is a herbaceous annual (a plant that completes
its life-cycle in one year) in the Asteraceae (Sunflower) family. The
plant is typically 15 to 40 cm (6 to 16 in) in height, multi-branched,
procumbent or ascending--decumbent (trailing or lying on the ground),
and densely pubescent (covered with hair) with coarse, stiff hair. One
to 4 flower heads are produced per plant, each 5 to 7 mm (0.2 to 0.3
in) across with a white corolla (ray and disk flowers), and producing
tan-colored achenes (fruit) to 1 mm (0.04 in) in length. The very small
flower heads, coupled with entire (toothless) leaves are key factors
distinguishing this species from close relatives (Nesom 1989, p. 306).
Habitat and Biology
Oak Grove Canyon, where the plant has been most recently located,
is a narrow slot canyon with intermittent stream flow and a riparian
gallery forest of sycamore, alder, and black walnut (Gori 1992, p. 2).
Occurring at 1,000-m (3,300-ft) elevation, its steep (91 to 122 m) (300
to 400 ft)) canyon walls and northeast aspect provide for significantly
cooler temperatures than the semidesert grasslands in the adjacent
uplands (Haberstich 2011, pers. comm.). The plants are found on sandy
terraces just above the floodplain and are subject to larger flood
events; there is little associated understory (Gori 1992, p. 2). A
single collection from Turkey Creek refers to a ``riparian woodland''
habitat, while the specimen from Fish Creek has no habitat information
recorded. The collection from near Tucson refers to the plant being
found ``in rock adjacent to stream.'' (Southwest Environmental
Information Network 2011)
Erigeron piscaticus germinates following either winter or summer
rains (Arizona Game and Fish Department (AZGD) Heritage Data Management
2001, p. 2), grows quickly, and has a long flowering period from May
through October (Gori 1992, p. 2) or possibly through December
(Southwest Environmental Information Network, 2011). Pollination has
not been studied in this species, though other Erigeron species are
typically pollinated by bees and wasps (Tepedino 2011, pers. comm.).
Seed is dispersed by both wind and water; this species may also depend
on flooding events to create suitable early-successional habitat (Gori
1992, p. 2). Seed bank longevity has not been studied in E. piscaticus.
Soil moisture is necessary for most annual plants to germinate and
flower; therefore, seed production in most annuals is equally limited
by soil moisture. Following this theory, Gori (1992, p. 3) suggested
that Erigeron piscaticus populations would increase or decrease in
sequential years of above- or below-average moisture. In the case of
data collected at Oak Grove Canyon, this theory held in 1993, a wet
year, when both 1994 and 1995 had high population numbers (79 and 68
respectively). However, the theory did not hold in 2002, a dry year,
when 23 plants were found in 2003 followed by 64 plants in 2004. It is
likely that this species instead responded to flooding that occurred in
1993 and not to precipitation. There is not sufficient data available
to determine the ecological factors that influence the germination of
this species.
Distribution, Abundance, and Trends
Erigeron piscaticus is ranked by NatureServe as G1S1 (Global and
State Critically Imperiled). The species is known from two confirmed
areas: Fish Creek Canyon and the Aravaipa Canyon Preserve of south-
central Arizona. There are three populations in the Aravaipa Canyon
Preserve; one is located in Turkey Creek Canyon, and the
[[Page 62737]]
remaining two populations are in Oak Grove Canyon. An additional site
is currently under investigation in the mountains near Tucson. The
herbarium specimen location for this third site states ``Box Canyon
southwestern corner of Santa Catalina Mountains;'' the specimen was
verified by Guy Nesom, the botanist who described the species
(Southwest Environmental Information Network 2011). There have been
discussions among botanists, however, that this location may be
incorrect and Box Canyon could refer to either the Rincon or Santa Rita
Mountains. It is also possible that the specimen was misidentified and
the location is correct. The specimen currently resides at the New York
Botanic Garden Herbarium and a loan has been requested by Shelley
McMahon of the University of Arizona Herbarium for reverification.
Surveys for the species are planned in 2012 (Crawford 2011, pers.
comm.).
The species was first collected on the Tonto National Forest in
Fish Creek Canyon in October 1929 by Eastwood, then again in 1931 by
Peebles and Eaton (Nesom 1989, p. 305). Erigeron piscaticus was not
collected again until 1976 in Turkey Creek then in 1979 in Oak Grove
Canyon by Anderson and Warren (Southwest Environmental Information
Network 2011). In 2002, a second group of plants was located in Oak
Grove Canyon and those plants are counted as part of an annual census
for the canyon as a whole (Haberstich and Killeen 2002, p. 1). Both
Turkey Creek and Oak Grove Canyon are within the Aravaipa Canyon
Preserve on Bureau of Land Management land managed jointly with The
Nature Conservancy. The two locations within Oak Grove Canyon are
approximately 0.8 km (0.5 mi) apart by air and the Oak Grove
populations are approximately 3.7 air km (2.3 air mi) from the
collection site in Turkey Creek. The Fish Creek locations are
approximately 129 air km (80 air mi) from those in Aravaipa Preserve.
There are many canyons supporting what seems to be suitable habitat
between the known locations in Fish Creek and the Aravaipa Canyon
Preserve. Several surveys have been completed, and no additional
populations have been located (Gori 1991, p. 2).
Attempts were made in 1990 to locate the populations in both Fish
Creek and Turkey Creek again, but none were found (Gori and Malusa
1991, p. 2). The Arizona Game and Fish Department reports 11 plants
were located in Turkey Creek in 1992, although no other records
indicate the plant has been found in Turkey Creek since its first
collection in 1976. A letter in the files from Dave Gori to Dan Godec
of the Arizona Game and Fish Department dated June 12, 1998 stated that
E. piscaticus has not been relocated in Fish Creek Canyon or Turkey
Creek Canyon. He related that, to his knowledge, there were ``no other
extant locations for this plant except Oak Grove Canyon.'' It is
unknown how many plants originally occurred at collection sites in Fish
Creek or Turkey Creek Canyons. As these populations have not been
detected again, it is unknown if they are extant or what the current
population sizes are. Annual monitoring of plants in Oak Grove Canyon
took place between 1992 and 2008 and is scheduled to occur in the
summer of 2011 (Haberstich 2011, pers. comm.). These efforts show plant
numbers fluctuating annually, ranging from 87 individuals in 1992, to 4
individuals in 2002, and back to 81 individuals in 2008.
To summarize, there is very little biological and ecological
information known about this species. There are three known locations,
but plants have not been seen in the original location, Fish Creek,
since the 1930s. Today, plants are known from two locations, Oak Creek
Canyon and Turkey Creek on the Aravaipa Canyon Preserve. There may be
another location in the Santa Catalina Mountains, near Tucson, but it
has not been verified. The species seem to be associated with
floodplain terraces in riparian areas, but that is based on their
current locations in the Aravaipa Canyon Preserve. The species may
respond to rainfall, or germination may be triggered by flooding, or
the apt combination of rainfall and flooding.
Five-Factor Evaluation for Erigeron piscaticus
In making this finding, information pertaining to Erigeron
piscaticus in relation to the five factors provided in section 4(a)(1)
of the Act is discussed below.
Factor A. The Present or Threatened Destruction, Modification, or
Curtailment of Its Habitat or Range
Potential factors that may affect the habitat or range of Erigeron
piscaticus are discussed in this section, including: (1) Flooding; (2)
recreation; (3) watershed degradation; and (4) climate change.
Flooding
Many annual and short-lived perennial plant species have a high
rate of seed production and the ability to thrive following
disturbance. Annual plants in the southwestern United States often
increase in richness and cover following the disturbance of large flood
events (Bagstad et al. 2005, p. 219). These events reduce competition
with perennial plants, increase understory light, remove litter
accumulation from overstory tree species, redistribute seed banks, and
create nutrient-rich sediment beds for seed germination. Plants found
above the inundation zones on high flood-plain surfaces respond most to
the increased rainfall that led to flooding, while those in inundation
zones respond most to the physical disturbance of flooding (Bagstad et
al. 2005, p. 219, 221). Erigeron piscaticus is an annual riparian
species that occurs above the inundation zone on shallow terraces that
are subject to larger flooding events.
Census data for this species were collected on a nearly annual
basis between 1992 and 2008, in one of two locations within the
Aravaipa Canyon Preserve, in southeastern Arizona. Plant census data
were compared against regional precipitation data during this time
period, and no correlation was observed. In other words, population
peaks varied between wet (1991 through 1995) and dry (2004 and 2008)
years (NOAA 2011; Haberstich and Walker 2008, p. 1; Haberstich 2005, p.
1; Haberstich and Killeen 2004, p. 1; 2003, p. 1; 2002, p. 1;
Haberstich 2011, pers. comm.). Aravaipa Creek has experienced
significant flooding on four occasions (1979, 1984, 1993, and 2006)
since stream flow gage records were first kept in 1932 (USGS, 2011).
Erigeron piscaticus may be more closely associated with the physical
scouring from flooding than with precipitation. E. piscaticus
populations peaked following both the 1993 and 2006 floods.
Although periodic flooding events remove individual plants and
seeds, total Erigeron piscaticus population numbers were very similar
during the 2008 monitoring (81) to numbers the first time the species
was monitored in 1992 (87). There is, however, great year-to-year
variability in the census data, both in terms of population numbers (as
low as 4 plants in 2002, and as high as 87 plants in 1992) and
population locations (lower, middle, and upper sections of the canyon).
The species seems to establish, increase and decrease; disperse via
water or wind; and move to different locations within the canyon, which
may explain the new location discovered downstream from known sites in
2002. In addition, in particularly dry years, plants may not germinate.
This may explain why certain populations, like Fish Creek, have never
been found again. If the populations are not present every year, and
the location may move within the canyon based on flooding, it is easy
to
[[Page 62738]]
understand why populations need regular and consistent monitoring.
Erigeron piscaticus seems to be well adapted to its environment and
may require periodic flooding for survival. Too many large floods,
however, could deplete the seed bank; too few large floods could lead
to competition with perennial plants and litter accumulation (Gori
1992, p 3). We are making this conclusion based on the behavior of one
population; however, this population may not be representative of the
species. We conclude that E. piscaticus is tolerant of moderate
disturbance and may need periodic flooding for successful seed
germination. Therefore, based on the best available information, we
determined that flooding is not a threat to the continued existence of
E. piscaticus, nor is it likely to become so.
Recreation
Erigeron piscaticus plants are located near hiking and game trails
in Oak Grove Canyon. Hiking and other forms of recreation, including
all-terrain vehicle (ATV) use, occur frequently in the Aravaipa Canyon
Preserve (Haberstich 2005, p. 1; Haberstich and Killeen 2004, p. 1). As
stated above, this species seems to tolerate moderate levels of
disturbance. The populations in Oak Grove Canyon seem to be persisting
despite the levels of traffic, both human and ATV, that occur adjacent
to and through the populations. There are also observations (Haberstich
2005, p. 1; Haberstich and Killeen 2004, p. 1) that E. piscaticus
plants were found in various stages of germination and growth on an
actively eroding site, another indication that the species tolerates
disturbance. Impacts from recreation may have contributed to the loss
of the Turkey Creek population in the Aravaipa Canyon Preserve, as the
site was used as a casual camping site (AZGF Heritage Data Management
2001, p. 3). However, there is no documentary evidence that that is the
case, and because no one has surveyed that area since the 1990s, there
is no conclusive evidence that the population has been extirpated. In
summary, E. piscaticus seems to tolerate disturbance, and, based on the
best available information, we find that recreation is not a threat to
the continued existence of this species, nor is it likely to become so.
Watershed Degradation
The Aravaipa Canyon watershed has a history of intense grazing by
cattle, horses, and goats. This grazing occurred from the 1850s until
the 1980s when grazing was removed from portions of the area and a
pasture rotation system was initiated in other areas (Gori 1992, p. 4).
By 1997, the entire area, including Oak Grove and Turkey Creek Canyons,
was free of domestic grazing activity (Haberstich 2011, pers. comm.).
The years of intense grazing, coupled with fire suppression,
significantly altered plant species composition and abundance, and led
to a degraded condition of the upland vegetation of the area (Gori
1992, pp. 3-4). By the 1980s, this upland semidesert grassland was
described as being largely comprised of shrubs and annual grasses, an
unnatural condition that reduces water infiltration and can cause more
intense sheet flow during storm events (Gori 1999, pp. 41-42). Great
strides have been made in recent decades to correct this problem.
Preserve Manager Mark Haberstich reports that the uplands are fairly
healthy with increases in native perennial grasses, thus reducing
runoff and erosion (Haberstich 2011, pers. comm.). There is no evidence
that watershed degradation is affecting E. piscaticus populations in
the Aravaipa Canyon Preserve. Therefore, based on our review of the
best available information, we conclude that watershed degradation is
not a threat to the continued existence of this species, nor is it
likely to become so.
Climate Change
For general background information on climate change, please refer
to the first paragraphs of ``Climate Change'' under Factor A. The
Present or Threatened Destruction, Modification, or Curtailment of Its
Habitat or Range in the Five-Factor Evaluation for Amoreuxia gonzalezii
section.
It has been suggested that this species may be a relict of the last
ice age due to its very restricted habitat of cool, shady, narrow, and
steep slot canyons in perennial stream bottoms (Haberstich 2011, pers.
comm.). If this is the case, recent and projected increases in regional
daily temperatures and decreases in winter precipitation could
negatively impact Erigeron piscaticus. Direct impacts due to rising
temperature are unknown for this plant, although heat stress in plants
in general is known to impact germination, photosynthesis, respiration,
and a myriad of other functions (Wahid et al. 2007, p. 199). A
reduction in precipitation or increase in temperature-related stress
could preclude recruitment and therefore seed set in this annual
species. Seed bank longevity for E. piscaticus has not been determined,
although Bagstad et al. (2005, p. 219) state that ``many of the annual
plant species found in southwestern riparian areas have long-lived
seeds that are widely distributed in soil seed banks across the flood
plain, enabling them to establish opportunistically when suitable
germination sites develop.'' Similarly, other Erigeron seeds have been
reported to last roughly 10 years with no refrigeration (Murray 2011,
pers. comm.).
The information related to the effects of climate change on
Erigeron piscaticus at a local scale is limited. Predicted changes in
rainfall, temperature, and flooding frequency may all affect E.
piscaticus. However, based on the species' life history and observed
tolerances, it appears that the effects of climate change may be
limited. In conclusion, based on the best available information, we
have determined that climate change is not a threat to the continued
existence of E. piscaticus.
Summary of Factor A
Based on the best available information, we have determined that
flooding, recreation, watershed degradation, and climate change do not
threaten Erigeron piscaticus, nor are they likely to do so. Flooding
seems to play an important role in the germination and survival of E.
piscaticus populations. As such, the species seems to tolerate moderate
levels of disturbance, making the populations less vulnerable to
impacts from recreation, such as hiking and ATV use. The watershed
condition of Aravaipa Canyon has recovered from past grazing, and there
is no evidence that E. piscaticus populations have been affected by
watershed degradation. We acknowledge that climate change, particularly
the predictions of reduced precipitation and increasing temperatures in
the Southwest, may affect populations of E. piscaticus; however, the
limited available information at the local scale suggests that a
climate change will likely not be a threat to the continued existence
of the species. Thus, the present or threatened destruction,
modification, or curtailment of the habitat or range is not a threat to
the continued existence of E. piscaticus, nor is it likely to become
so.
Factor B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
Erigeron piscaticus is not a plant of horticultural interest. There
is no evidence of any instances in which E. piscaticus was collected
from the wild other than as voucher specimens to document occurrences
(http://ag.arizona.edu/herbarium). Therefore, we conclude, based on the
best available information, that overutilization is not a threat to the
continued existence of the species, nor is it likely to become so.
[[Page 62739]]
Factor C. Disease or Predation
There is no indication that any disease affects Erigeron
piscaticus. There is no livestock grazing in Oak Grove Canyon and
Turkey Creek on the Aravaipa Canyon Preserve, and there is no
information about any other source of predation on the species.
Therefore, we have determined that disease or predation is not a threat
to this species' continued existence, nor is it likely to become so.
Factor D. The Inadequacy of Existing Regulatory Mechanisms
The Act requires us to examine the adequacy of existing regulatory
mechanisms with respect to threats that may place Erigeron piscaticus
in danger of extinction or likely to become so in the future. Existing
regulatory mechanisms that could have an effect on potential threats to
E. piscaticus include (1) Local land use laws, processes, and
ordinances; (2) State laws and regulations; and (3) Federal laws and
regulations. E. piscaticus occurs entirely on Federal land under the
jurisdiction of the Bureau of Land Management (BLM) and the Tonto
National Forest; therefore, the discussion below focuses on Federal
laws.
Erigeron piscaticus is listed as a BLM sensitive species (BLM,
2010). The management of sensitive species is described in the BLM
Manual Section 6840, which states that the BLM will focus sensitive
species management on maintaining species habitat in functional
ecosystems, ensuring the species is considered in land management
decisions, and prioritizing conservation that emphasizes habitat needs
for the species, thereby preventing the need to list the species under
the Act.
Erigeron piscaticus is also listed as a sensitive species in the
Tonto National Forest (Tonto National Forest 2004, entire). The
management of sensitive species is described in U.S. Forest Service
Manual (FSM) 2670, and the management objectives are to develop and
implement management practices to ensure that species do not become
endangered or threatened because of Forest Service actions; maintain
viable populations of all native and desired nonnative wildlife, fish,
and plant species in habitats distributed throughout their geographic
range on National Forest System lands; and develop and implement
management objectives for populations or habitat of sensitive species,
or both. In addition, the Forest has to consider the effects of their
actions on the viability of sensitive species through the NEPA process.
As defined by Forest Service policy, actions must not result in loss of
species viability or create significant trends toward the need for
Federal listing. E. piscaticus receives these protective measures in
the Tonto National Forest.
Summary of Factor D
We examined the existing regulatory mechanisms that protect
Erigeron piscaticus. We have determined that the BLM and Forest Service
sensitive species designation adequately protects E. piscaticus and its
habitat and, thus, there is no evidence of impacts to E. piscaticus
from inadequate existing regulatory mechanisms. We conclude that the
best available information indicates that E. piscaticus is not
threatened by inadequate existing regulatory mechanisms.
Factor E. Other Natural or Manmade Factors Affecting Its Continued
Existence
Small Population Size
Small populations can be especially vulnerable to environmental
disturbances such as habitat loss, nonnative species, grazing, and
climate change (Barrett and Kohn 1991, p. 7; Oostermeijer 2003, p. 21;
O'Grady 2004, pp. 513-514). However, plants that are historically rare
may have certain adaptations to rarity (e.g., early blooming, extended
flowering, or mixed-mating systems) that enable them to persist
(Brigham 2003, p. 61). For more information on species rarity and its
effects on the conservation status of a species, see the discussion
under Factor E. Other Natural or Manmade Factors Affecting Its
Continued Existence in the Five-Factor Evaluation for Amoreuxia
gonzalezii.
There is no indication that Erigeron piscaticus was ever present on
the landscape over a more extensive range than it is today. Existing
sites are monitored, and surveys have located no new occurrences. There
is no information indicating that random demographic or environmental
events are a threat to the continued existence of the species because
of its small population size.
Genetic Diversity
Small population size can decrease genetic diversity due to genetic
drift (the random change in genetic variation each generation), and
inbreeding (mating of related individuals) (Antonovics 1976, p. 238;
Ellstrand and Elam 1993, pp. 218-219). Genetic drift can decrease
genetic variation within a population by favoring certain
characteristics and, thereby, increasing differences between
populations (Ellstrand and Elam 1993, pp. 218-219). Self-fertilization
and low dispersal rates can cause low genetic diversity due to
inbreeding (Antonovics 1976, p. 238; Barrett and Kohn 1991, p. 21).
This decreased genetic diversity diminishes a species' ability to adapt
to the selective pressures of a changing environment (Newman and Pilson
1997, p. 360; Ellstrand 1992, p. 77).
Limited information is available regarding the genetic diversity of
the Erigeron genus. No information is available regarding the genetic
diversity exhibited by E. piscaticus. Therefore, we have determined
that a lack of genetic diversity is not a threat to the continued
existence of the species.
Summary of Factor E
Erigeron piscaticus is a rare species known from two locations,
Fish Creek Canyon and the Aravaipa Canyon Preserve. Currently, there
are two known populations in Oak Creek Canyon, within the Aravaipa
Canyon Preserve. The other populations of E. piscaticus in Fish Creek
Canyon and Turkey Creek Canyon, in the Aravaipa Canyon Preserve, have
not been seen in quite some time. There is no evidence that this
species was at one time more widespread than its current distribution.
There is no information that E. piscaticus populations are subject to
threats resulting from small population size. The same conclusion is
drawn for the lack of genetic diversity that may affect small
populations. Therefore, based on the best available information, we
have determined that small population size and lack of genetic
diversity are not threats to the continued existence of E. piscaticus,
nor are they likely to become so.
Finding for Erigeron piscaticus
As required by the Act, we considered the five factors in assessing
whether Erigeron piscaticus is endangered or threatened throughout all
or a significant portion of its range. We examined the best scientific
and commercial information available regarding the past, present, and
future threats faced by E. piscaticus. We reviewed the petition,
information available in our files, other available published and
unpublished information, and we consulted with recognized plant experts
and land managers.
Erigeron piscaticus populations do not seem to face any obvious
threats. The species is an annual, which means that there is less
certainty about the size, location, and permanence of any given site.
In addition, the species tolerates,
[[Page 62740]]
and may possibly require, disturbance in order to complete its life
cycle. The only available information is monitoring data from one
location, and two of the other locations have not been seen in quite
some time, although attempts to find these populations again have not
occurred. As such, there is an incomplete set of information about this
species, which makes it difficult to assess threats and make valid
predictions on how potential threats may affect E. piscaticus. For
instance, climate change will affect temperature and precipitation in
the Southwest, but it is not known what that means for changes in
flooding, and how that will affect E. piscaticus.
Other factors potentially affecting Erigeron piscaticus--including
recreation and watershed degradation--are either limited in scope, or
lacking evidence indicating that they adversely impact the species.
There is no evidence that overutilization, disease, or predation are
affecting this species. Although the existing populations are small,
there is no evidence that the populations are subject to a lack of
genetic diversity or are more vulnerable to stochastic events. In
addition, we conclude that the inadequacy of existing regulatory
mechanisms is not a threat to the species.
Based on our review of the best available scientific and commercial
information pertaining to the five factors, we find that the threats
are not of sufficient imminence, intensity, or magnitude to indicate
that Erigeron piscaticus is in danger of extinction (endangered) or
likely to become endangered within the foreseeable future (threatened),
throughout all of its range.
Significant Portion of the Range
Having determined that Erigeron piscaticus is not in danger of
extinction, or likely to become so, throughout all of its range, we
must next consider whether there are any significant portions of the
range where E. piscaticus is in danger of extinction or is likely to
become endangered in the foreseeable future. We also considered the
historical range of the species, and have determined that the current
range is no different from the historical range. Therefore, there has
been no loss of the historical range, and no further analysis of the
historical range is required.
The Act defines an endangered species as one ``in danger of
extinction throughout all or a significant portion of its range,'' and
a threatened species as one ``likely to become an endangered species
within the foreseeable future throughout all or a significant portion
of its range.'' The term ``significant portion of its range'' is not
defined by the statute. For the purposes of this finding, a portion of
a species' range is ``significant'' if it is part of the current range
of the species, and it provides a crucial contribution to the
representation, resiliency, or redundancy of the species. For the
contribution to be crucial it must be at a level such that, without
that portion, the species would be in danger of extinction.
In determining whether Erigeron piscaticus is endangered or
threatened in a significant portion of its range, we considered status
first to determine if any threats or potential threats acting
individually or collectively threaten or endanger the species in a
portion of its range. We evaluated the current range of E. piscaticus
to determine if there is any apparent geographic concentration of the
primary stressors potentially affecting the species including flooding,
recreation, and watershed degradation. We have analyzed the stressors
to the degree possible, and determined that they are essentially
uniform throughout the species' range. We also found the stressors are
not of sufficient imminence, intensity, magnitude, or geographically
concentrated such that it warrants evaluating whether a portion of the
range is significant under the Act. We do not find that E. piscaticus
is in danger of extinction now, nor is likely to become endangered
within the foreseeable future, throughout all or a significant portion
of its range. Therefore, listing E. piscaticus as an endangered or
threatened species under the Act is not warranted at this time.
Conclusion of 12-Month Finding
We find that Amoreuxia gonzalezii (Santa Rita yellowshow),
Astragalus hypoxylus (Huachuca milk-vetch), and Erigeron piscaticus
(Fish Creek fleabane) are not in danger of extinction now, nor is any
of these three species likely to become endangered within the
foreseeable future throughout all or a significant portion of their
ranges. Therefore, listing any of these three species as endangered or
threatened under the Act is not warranted at this time.
We request that you submit any new information concerning the
distribution and status of, or threats to, Erigeron piscaticus to our
U.S. Fish and Wildlife Service Office (see ADDRESSES section) whenever
it becomes available. New information will help us monitor E.
piscaticus and encourage its conservation. If an emergency situation
develops for E. piscaticus or any other species, we will act to provide
immediate protection.
References Cited
A complete list of references cited is available on the Internet at
http://www.regulations.gov and upon request from the U.S. Fish and
Wildlife Service, Arizona Ecological Services Field Office (see
ADDRESSES section).
Authors
The primary authors of this finding are the staff members of the
Arizona Ecological Services Field Office.
Authority
The authority for this action is section 4 of the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: September 22, 2011.
Gregory E. Siekaniec,
Acting Director, Fish and Wildlife Service.
[FR Doc. 2011-25470 Filed 10-7-11; 8:45 am]
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