[Federal Register Volume 73, Number 138 (Thursday, July 17, 2008)]
[Proposed Rules]
[Pages 41007-41022]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: E8-16041]
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DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[FWS-R8-ES-2008-0081; 92220-1113-0000-C5]
Endangered and Threatened Wildlife and Plants; 12-Month Finding
on a Petition To Delist Astragalus magdalenae var. peirsonii (Peirson's
milk-vetch)
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 remove Astragalus magdalenae var.
peirsonii (Peirson's milk-vetch) from the Federal List of Threatened
and Endangered Plants under the Endangered Species Act. After reviewing
the best scientific and commercial information available, we find that
the petitioned action is not warranted. We ask the public to submit to
us any new information that becomes available concerning the status of,
or threats to, the species. This information will help us monitor and
encourage the conservation of this species.
DATES: The finding announced in this document was made on July 17,
2008.
ADDRESSES: This finding is available on the Internet at http://www.regulations.gov, http://www.fws.gov/endangered, and http://www.fws.gov/Carlsbad. Supporting documentation we used in preparing
this finding is available for public inspection, by appointment, during
normal business hours at the Carlsbad Fish and Wildlife Office, U.S.
Fish and Wildlife Service, 6010 Hidden Valley Road, Carlsbad, CA 92011;
telephone 760-431-9440; facsimile 760-431-5901. Please submit any new
information, materials, comments, or questions concerning this finding
to the above street address or via electronic mail (e-mail) at
[email protected].
FOR FURTHER INFORMATION CONTACT: Jim Bartel, Field Supervisor, U.S.
Fish and Wildlife Service, Carlsbad Fish and Wildlife Office (see
ADDRESSES section). If you use a telecommunications device for the deaf
(TDD), call the Federal Information Relay Service (FIRS) at 800-877-
8339.
SUPPLEMENTARY INFORMATION:
Background
Section 4(b)(3)(A) of the Endangered Species Act (Act) (16 U.S.C.
1531 et
[[Page 41008]]
seq.) requires that we make a finding on whether a petition to list,
delist, or reclassify a species presents substantial information to
indicate the petitioned action may be warranted. Section 4(b)(3)(B) of
the Act requires that within 12 months after receiving a petition to
revise the Lists of Threatened and Endangered Wildlife and Plants
(Lists) that contains substantial information indicating that the
petitioned action may be warranted, the Secretary shall make one of the
following findings: (a) The petitioned action is not warranted, (b) the
petitioned action is warranted, or (c) the petitioned action is
warranted but precluded by pending proposals to determining whether any
species is an endangered or threatened species and expeditious progress
is being made to add qualified species to, and remove species from, the
Lists. Such 12-month findings are to be published promptly in the
Federal Register.
Astragalus magdalenae var. peirsonii (Peirson's milk-vetch) was
listed as threatened on October 6, 1998 (63 FR 53596). At the time of
listing, the primary threat to A. magdalenae var. peirsonii was the
destruction of individuals and dune habitat from off-highway vehicle
(OHV) use and associated recreational development. On October 25, 2001,
we received a petition to delist A. magdalenae var. peirsonii dated
October 24, 2001, from David P. Hubbard, Ted J. Griswold, and Philip J.
Giacinti, Jr. of Procopio, Cory, Hargreaves & Savitch, LLP, that was
prepared for the American Sand Association (ASA), the San Diego Off-
Road Coalition, and the Off-Road Business Association (ASA 2001). On
September 5, 2003, we announced a 90-day finding in the Federal
Register that the petition presented substantial information to
indicate the petitioned action may be warranted (68 FR 52784). In
accordance with section 4(b)(3)(A) of the Act, we completed a status
review of the best available scientific and commercial information on
the species, and published our 12-month finding on June 4, 2004 (69 FR
31523). We determined that the petitioned action was not warranted at
that time.
On July 8, 2005, we received an updated petition to delist
Astragalus magdalenae var. peirsonii (Peirson's milk-vetch) that was
prepared by David P. Hubbard for the American Sand Association, the
Off-Road Business Association, the San Diego Off-Road Coalition, the
California Off-Road Vehicle Association, and the American Motorcycle
Association District 37 (ASA 2005). On November 30, 2005, we announced
our 90-day finding that the updated petition presented substantial
scientific or commercial information indicating that the petitioned
action may be warranted, and initiated a status review for A.
magdalenae var. peirsonii (70 FR 71795). The updated petition claims to
``demonstrate, through four years of additional data collection, that
the Peirson's milk-vetch is even more abundant than was reported in
ASA, et al.'s original petition, and that the plant's population and
reproductive capacity are so stable and strong as to warrant
delisting'' (ASA 2005, p. 5).
Included again in the updated petition and its associated documents
(ASA 2005) is the assertion made in the ASA 2001 petition that
Astragalus magdalenae var. peirsonii was listed without the support of
abundance data. That assertion was addressed in our June 4, 2004, 12-
month finding (69 FR 31523) on their previous petition to delist A.
magdalenae var. peirsonii, and the updated petition did not provide any
additional information that would alter our previous analysis. All of
the information in our prior (June 4, 2004) 12-month finding (69 FR
31523) applies to this action, and the status review provided in this
document continues to validate that our original decision to list A.
magdalenae var. peirsonii as a threatened species (63 FR 53596) was not
made in error or without supporting data.
Species Information
Species Description
Astragalus magdalenae var. peirsonii (Peirson's milk-vetch) is an
erect to spreading, herbaceous, short-lived perennial in the Fabaceae
(Pea family) (Barneby 1959, 1964). Plants may reach 8 to 27 inches (in)
(20 to 70 centimeters (cm)) in height and develop taproots (Barneby
1964, pp. 862-863) that penetrate to the deeper, moister sand.
According to Phillips and Kennedy (2003), plants largely die back to a
root crown in the summer. The stems and leaves are covered with fine,
silky appressed hairs. The leaflets, which may fall off in response to
drought, are small and widely spaced, giving the plants a brushy
appearance. This taxon is unusual in that the terminal leaflet (leaflet
at the tip) is continuous with the rachis (the central axis of a
compound leaf along which leaflets are attached) rather than
articulated with it (Barneby 1959, p. 879; Spellenberg 1993, p. 598).
Each flower stalk (classified as a raceme) arises from a point where a
leaf joins the stem (axil), and supports 10 to 17 purple flowers
(Barneby 1959, p. 879).
Taxonomy
The taxonomic status of Astragalus magdalenae var. peirsonii was
discussed in the final listing rule (63 FR 53596). Although originally
described at the species rank, Peirson's milk-vetch is currently
recognized at the varietal level as A. magdalenae var. peirsonii
(Spellenberg 1993, p. 598). Although two other recognized varieties
exist for A. magdalenae, these taxa are restricted to Mexico. However,
recent genetic analysis suggests that Barneby's (1964, pp. 862-863)
reduction of A. peirsonii to varietal status may be inappropriate and
that A. magdalenae var. peirsonii should be recognized as a species [as
originally described by Munz and McBurney (Munz 1932, p. 7)] (Porter
and Prince 2006, p. 7; 2007, pp. 10-11).
Two other Astragalus taxa occur in the vicinity of the Algodones
Dunes. They are A. lentiginosus var. borreganus (Spellenberg 1993, p.
597), easily distinguished by its conspicuously broad leaflets, and A.
insularis var. harwoodii (Spellenberg 1993, p. 594), which is easily
distinguished by its smaller stature and shorter banner petals.
Range and Distribution
In the United States, Astragalus magdalenae var. peirsonii is
restricted to specific habitat areas within about 53,000 acres (ac)
(21,500 hectares (ha)) in a narrow band running 40 miles (64
kilometers) northwest to southeast along the western portion of the
Algodones Dunes (= Imperial Sand Dunes) of eastern Imperial County,
California, which is the largest sand dune field in North America.
Astragalus magdalenae var. peirsonii has also been documented from the
Gran Desierto of Sonora, Mexico (Felger 2000, p. 300), from an area
south and southeast of the Sierra Pinacate lava field, but the Service
has no additional information on the extent of area occupied, the size
of the population, or its current condition (see 63 FR 53599).
Astragalus magdalenae var. peirsonii was also noted from the Borrego
Valley, California, by Barneby (1959, p. 879), but not verified,
reproducing population exists (Porter et al. 2005, pp. 9-10). Other
observations from Yuma, Arizona, and San Felipe, Baja California,
Mexico, were based on misidentified specimens (see Porter et al. 2005,
pp. 9-10, and Phillips et al. 2001, p. 7, for detailed accounts).
The Algodones Dunes are often referred to as the Imperial Sand
Dunes. Nearly all of the lands in the Algodones Dunes are managed by
the Bureau of Land Management (BLM) as the Imperial Sand Dunes
Recreation Area
[[Page 41009]]
(ISDRA). However, the State of California and private individuals own
small inholdings in the dune area. On August 4, 2004, approximately
21,836 ac (8,838 ha) of the 167,800-ac (67,900-ha) ISDRA were
designated as critical habitat for Astragalus magdalenae var. peirsonii
(69 FR 47330). In a September 25, 2006, court order, the District Court
for the Northern District of California ordered the Service to submit a
new final critical habitat rule to the Federal Register for publication
no later than February 1, 2008 (Center for Biological Diversity et al.
v. Bureau of Land Management et al., Civ. No. C 03-2509 SI). On
February 14, 2008, the Service designated revised critical habitat for
A. magdalenae var. peirsonii (73 FR 8748). In total, approximately
12,105 ac (4,899 ha) in Imperial County, California, fall within the
boundaries of the revised designation of critical habitat.
Life History
Astragalus magdalenae var. peirsonii has variously been considered
an annual or perennial plant (Munz 1932, p. 7; 1974, p. 432; Barneby
1959, p. 879; 1964, p. 862; Spellenberg 1993, p. 598; Willoughby 2001,
p. 21; Porter et al. 2005, p. 7). Willoughby (2001, p. 21) observed
that A. magdalenae var. peirsonii is a short-lived perennial and, as
such, its response to rainfall was predictable. Recent evidence
confirms this observation (Phillips and Kennedy 2004, p. 5; Groom et
al. 2007, p. 121) and that, depending upon conditions and germinating
time, A. magdalenae var. peirsonii is capable of flowering before it is
a year old (Barneby 1964, p. 862; Romspert and Burk 1979 p. 16;
Phillips et al. 2001, p. 10; Phillips and Kennedy 2005, p. 22; Porter
et al. 2005, p. 31).
Based on current understanding of the species' life history,
sufficient rain in conjunction with cool fall temperatures appears to
trigger germination events. Seedlings are often present in suitable
habitat throughout the dunes, especially during above-normal
precipitation years. In intervening dry years, plant numbers decrease
as individuals die and are not replaced by new seedlings. Porter et al.
(2005, p. 35) estimated that a total or near-total failure of seedling
recruitment occurs 20 percent of the time (once every 5 years). This
species likely depends on the production of seeds in the wetter years
and the persistence of the seed bank from previous years to survive
until appropriate conditions for germination occur again. However,
individual plants that perennate (i.e., survive from year to year with
a period of reduced activity) likely give ``continuity'' to the
presence of Astragalus magdalenae var. peirsonii through years of low
recruitment (Beatley 1970, p. 331).
If winter rains begin in early November, seeds germinating in early
December may develop rapidly to produce flowering plants by February
and set seed in March (Barneby 1964, p. 862; Romspert and Burk 1979,
pp. 15-16). In wetter years, a second germination event may occur in
late winter (Phillips et al. 2001, p. 10; Phillips and Kennedy 2005, p.
22), but these plants often fail to reproduce and die in large numbers
at the onset of summer drought (Phillips et al. 2001, p. 10; Phillips
and Kennedy 2003, p. 20). If winter rains do not occur until late
January, sufficient soil moisture or time may not exist for young
plants to develop the root structure needed to flower and set seeds
before the onset of desiccating summer heat. Young plants often die
during summer drought in significant numbers probably because such
plants lack a sufficiently developed root system to tap water at lower
horizons, i.e. deeper soil layers. Older plants also die during this
period. However, some plants develop an adequate root system and
perennate to live 2 to 3 years. Some perennial individuals will flower
and produce seeds in years with no precipitation (Phillips and Kennedy
2006, pp. 5, 9; USFWS 2007, pp. 13, 15), thereby assuring the
continuity of the seed bank. Years with optimal or prolonged
precipitation may experience two or more germinations and increased
seed production (Phillips and Kennedy 2005, p. 20).
Plants, regardless of age, may flower from as early as mid-November
through May (Barneby 1964, p. 862; Phillips and Kennedy 2002, p. 2;
Porter et al. 2005, p. 11). The onset of germination and flowering are
expected to vary from year to year depending upon the timing of winter
rains. As a result, the life stages are coincident with cooler
temperatures and a likely hydrated dune substrate. Barneby (1964, p.
862), Phillips and Kennedy (2005, p. 22), and Porter et al. (2005, p.
34) recorded plants that germinate in November can produce fruit in as
little as 3 months. Mature fruits are found on plants from the
beginning of February to late June (Phillips and Kennedy 2005, p. 13;
Porter et al. 2005, pp. 22-24; Romspert and Burk 1979, p. 16), with
peak production occurring in March and April (USFWS 2007, Figure 6).
Not all plants, even those seemingly capable of flowering and even
under favorable conditions, flower in a given year (Phillips and
Kennedy 2003, p. 20; Willoughby 2005b, p. 11; USFWS 2007, p. 15). In
2005, the BLM surveys recorded that 75 percent of all plants counted
flowered (Willoughby 2005b, p. 11), while the Service recorded 54
percent of plants flowered during the 2006 surveys (USFWS 2007, p. 15).
Smaller first season specimens, if flowering, produce relatively few
flowers and contribute little to the seed bank of Astragalus magdalenae
var. peirsonii compared with larger, older individuals that have more
flowers (Romspert and Burk 1979, p. 19; Phillips and Kennedy 2005, p.
20). In low rainfall years, the reproductive output of older plants may
range from as few as one seed pod to hundreds of pods per plant
(Phillips and Kennedy 2005, pp. 16-17; USFWS 2007, p. 15). Phillips and
Kennedy (2002, p. 27) estimated that plants counted in the spring 2001
survey averaged five fruits per plant. From a small sample in winter
2001-2002, they calculated that plants about 6 months older had an
average of 171 fruits per plant (Phillips and Kennedy 2002, p. 27). In
the 2006 survey, the Service calculated the median number of pods per
plant on plants more than 1 year old at 139 (USFWS 2007, p. 15).
Pollination and Breeding System
Porter et al. (2005, p. 32) identified a white-faced, medium-sized,
solitary bee (Habropoda pallida) as the only effective pollinator of
Astragalus magdalenae var. peirsonii. Otherwise, little is known about
the pollination ecology of A. magdalenae var. peirsonii. Porter et
al.'s (2005, p. 34) preliminary experiments in the field and under
greenhouse conditions indicate that A. magdalenae var. peirsonii plants
are not capable of self-pollination, and thus require pollinators for
outcrossing. Moreover, Porter et al. (2005, p. 34) reported from
microscopic examination of hand-pollinated flowers that pollen from the
same flowers did not adhere to the stigmatic surface, while pollen from
another plant did adhere. Unless pollen grains adhere, fertilization
cannot occur. These results indicate that A. magdalenae var. peirsonii
exhibits traits consistent with self-incompatibility (Porter and Prince
2007, pp. 10-11). Self-incompatibility (SI) is a genetic mechanism in
plants that prevents self-fertilization, or fertilization by pollen
from plants that share the same SI allele. This means that inbreeding
depression is avoided because only pollen from plants that do not share
SI alleles with the maternal plant will be able to successfully
fertilize eggs (Frankham et al. 2002, pp. 37-38; Castric and Vekemans
2004, p. 2873). This observation is a significant
[[Page 41010]]
consideration for assessing the adequacy of population size, structure,
and function. Large populations of standing individuals, with high SI
allele diversity, are likely necessary to provide adequate numbers of
individuals that can potentially fertilize the available eggs and
ensure that seed is produced. In the Algodones Dunes, large SI allele
diversity may be necessary spatially across the dunes, and temporally
through periods of drought. Further research and modeling are necessary
to better understand the dynamics of the A. magdalenae var. peirsonii
breeding system and how the species may be responding to natural and
man-made disturbances within its range.
Seed Biology
Seed development. The fruits or pods of Astragalus magdalenae var.
peirsonii are 0.8 to 1.4 in (2 to 3.5 cm) long, single-chambered,
hollow, and inflated. Developing pods contain 11 to 16 ovules
(structures containing immature eggs, or seeds, prior to fertilization)
(Barneby 1964, p. 862). The seeds, among the largest seeds of any
Astragalus in North America (Barneby 1964, pp. 862-863), average less
than 0.1 ounce (oz) (15 milligrams (mg)) each in weight and are up to
0.2 in (4.7 millimeters (mm)) in length (Bowers 1996, p. 69; McKinney
et al. 2006, p. 85).
Only a portion of a pod's ovules develop into mature seeds. Some
desiccate, while others are lost to insects (McKinney et al. 2006, p.
85). Seeds are either dispersed locally by falling from partly opened
fruits (pods) retained on the parent plant or disperse over greater
distances by their release from fruits (pods) blown across the sand
after falling from the parent plant.
Seed germination. Astragalus magdalenae var. peirsonii seeds
require no pre-treatment to induce germination, but germination success
improved dramatically when the outer seed coat was scarified (e.g.,
scratched, chipped). Porter et al. (2005, p. 29) reported about 99.1
percent of scarified seeds germinated in laboratory trials, while only
5.3 percent of unscarified seeds germinated. However, in artificial
dune experiments, Porter et al. (2005, p. 29) reported the germination
rate dropped to 27 percent. In germination trials conducted by Romspert
and Burk (1979, pp. 45-46), 92 percent or more seeds germinated within
29 days at temperatures of 77 [deg]F (25 [deg]C) or less, and no seeds
germinated at temperatures of 86 [deg]F (30 [deg]C) or higher. This
observation indicates that seeds on the dunes likely germinate in the
cooler months of the year. Porter et al. (2005, p. 29) identified the
primary dormancy mechanism in A. magdalenae var. peirsonii is the
impermeability of the seed coat to water and demonstrated little loss
of viability in seeds stored for 5 years. Impermeability of the seed
coat to water as a dormancy mechanism is consistent with species having
a seed bank (Given 1994, p. 67; Bowers 1996, p. 71). Dispersed seeds
that do not germinate during the subsequent growing season become part
of the soil seed bank (Given 1994, p. 67).
Annual or short-lived perennial plant populations can fluctuate
between large numbers of plants to few or even no plants. Many species,
and Astragalus magdalenae var. peirsonii may be one of them, rely on
periodic ``rescue'' episodes from the seed bank where large numbers of
plants germinate when conditions are suitable (Elzinga et al. 1998, p.
285; Pake and Venable 1996, pp. 1433-1434). Lincoln et al. (1993, p.
223) define the soil seed bank as ``the store of dormant seed buried in
soil,'' the store of seeds that do not germinate when otherwise
adequate conditions are present. The number of seeds in the seed bank
changes, depending upon the balance between processes or factors that
remove seeds from the seed bank and those that contribute seeds to it.
Deposition to the A. magdalenae var. peirsonii seed bank depends upon
standing plants that successfully produce seeds. This deposition is
diminished to the extent that plants are precluded from adding seeds to
the seed bank (Harper 1977, pp. 457-468; Louda and Potvin 1995, pp.
240-243). Other decreases to the seed bank can be attributed to loss of
plants or reduced reproductive output due to herbivory (Louda 1982, pp.
47-49; Baron and Bros 2005, pp. 49-51), direct or indirect OHV damage
(Pavlik 1979, pp. 73-85), or environmental conditions (e.g., summer or
winter drought, wind blown sand damage, dune shifts, or deep burial)
(Baskin and Baskin 2001, pp. 149-160). Increases in the available seed
bank can be attributed to rescue episodes in years favorable for
reproduction (Pake and Venable 1996, p. 1434).
Development of a seed bank and the associated dormancy allows plant
species to grow, flower, and set seed in years with most favorable
conditions (Given 1994, p. 67). When measuring seed bank dynamics,
estimations of the rate of seed mortality and aging, the amount of seed
lost to predators, and the variability in germination events are among
the information considered necessary to determine the viability and
productivity of a seed bank (Elzinga et al. 1998, p. 284).
Abundance and Population Trend
The updated petition (ASA 2005, pp. 11-12, 38-46) asserts that
Astragalus magdalenae var. peirsonii is abundant and thriving, and
therefore should not be listed, and also again asserts that the
original listing (63 FR 53596) was made without the support of
abundance data. In fact, for a species that fluctuates widely in
numbers from year to year, an assessment of abundance may not be the
most meaningful measure of the likelihood of persistence. Assessing the
population trend, resilience, and long-term viability of A. magdalenae
var. peirsonii is more relevant but is complex due to (1) the large
fluctuations in numbers of above-ground plants from year to year (often
the result of variations in rainfall or other climate conditions from
year to year), and (2) the intricacies associated with studying and
understanding seed banks and their dynamics. Although abundance data
will not likely completely clarify the likelihood of persistence for A.
magdalenae var. peirsonii, we review the available data below because
it has been the subject of much discussion over recent years. The data
presented in this section supports our original decision to list A.
magdalenae var. peirsonii as threatened. In addition, we discuss the
suitability of comparing available surveys. This is relevant because
multiple years of survey data are needed to detect population trends,
and using data from different surveys together to detect a trend can
only be legitimately done if the survey methodologies are comparable.
Finally, we discuss the available data on seed production and seed bank
dynamics, which is also relevant to our analysis of the long-term
persistence of A. magdalenae var. peirsonii.
Overview of survey data. A number of abundance surveys have been
conducted for Astragalus magdalenae var. peirsonii. Early surveys
incorporated a methodology whereby plants encountered along driving or
walking transects covering the entire 167,000 ac (67,900 ha) ISDRA were
qualitatively indexed to an abundance value (see WESTEC 1977, Table 2-
3) and represented in quadrants measuring 0.45 mile on each side.
Analysis of these coarse, dune-wide surveys conducted by WESTEC in
1977, and BLM (Willoughby) in 1998 through 2002, could only provide
relative comparisons of mean abundance values between years. In
comparing survey results for these years, the species was most abundant
in 1998, the highest rainfall year, and least abundant in 2000, the
lowest rainfall year (Willoughby 2001,
[[Page 41011]]
p. 21; 2004, p. 10). Mean abundance values for the years 1998 through
2002 were based upon total plant counts ranging from 86 plants in 2000
to 5,930 plants in 2001 (Willoughby 2004, p. 36). From this comparative
analysis, Willoughby (2004, p. 26) determined that there was little
change in A. magdalenae var. peirsonii abundance between 1977 and 2002.
In 2001, Dr. Arthur M. Phillips began a multi-year effort to
monitor Astragalus magdalenae var. peirsonii. Astragalus magdalenae
var. peirsonii abundance values were tabulated for 4 years: 2001, 2003,
2005, and 2006. In 2001, during an initial reconnaissance of the dunes,
Phillips et al. (2001, p. 6) counted 71,926 A. magdalenae var.
peirsonii from 127 specific locations covering an unspecified area of
about 35,000 ac (14,165 ha) (Phillips and Kennedy 2002, p. 8, Appendix
A), and they therefore calculated a density of about 2 plants/ac (5/
ha). From the 127 locations, Phillips and Kennedy (2002, p. 10)
selected 25 monitoring sites to use for the multi-year effort. The
effective area (i.e., the total area represented by data) covered by
the 25 sites was about 138 ac (56 ha) (Phillips and Kennedy 2005, p.
9). Phillips and Kennedy reported 30,771 plants in 2001 (Phillips and
Kennedy 2002, Appendix A); 33,202 plants in 2003 (Phillips and Kennedy
2003, Appendix A); 77,922 plants in 2005 (Phillips and Kennedy 2005, p.
10); and 1,233 plants in 2006 (Phillips and Kennedy 2006, p. 6) for
these 25 monitoring sites. Plant density ranged from 565 plants/ac
(1,392/ha) in 2005, to 8.9 plants/ac (22/ha) in 2006. In addition, in
2005 and 2006, Phillips and Kennedy used the data from the 25
monitoring sites to estimate the population for 60 of their original
sites at 173,328 and 2,035, respectively (Phillips and Kennedy 2005, p.
11; 2006, p. 6).
The BLM embarked on a new sampling methodology in 2004 that sampled
a larger portion of the dunes in greater detail (Willoughby 2005a, pp.
1-5), and increased the number of sample transects from 135 in 2004 to
510 for the spring 2005 surveys (Willoughby 2005b, p. 2). Willoughby's
(2005a and 2005b) analyses were based upon these sample transects,
which were comprised of 37,169 25-by-25-meter sample cells in 2004
(USFWS 2006a, Table 1) and 123,488 sample cells in 2005 (USFWS 2006b,
Table 1). Willoughby (2005a, Table 1-1) estimated the total population
size at 286,374 plants in 2004, for an estimated density of 5.5 plants/
ac (13.5/ha). Plants were most abundant in 2005 in what was an
exceptional year with well-timed rainfall and cool temperatures from
October 2004 through March 2005 (Willoughby 2005b, p. 6). In 2005,
Willoughby (2005b, Table 4) estimated 1,831,076 plants were in the
dunes, with an estimated density of 35 plants/ac (86.3/ha). A
randomized sample of 2005-occupied cells during the very dry winter and
spring of 2006 yielded an estimated population size of 83,451 plants,
or 1.5 plants/ac (3.9/ha) (Willoughby 2006, p. 6). The effective area
of these surveys covered about 53,000 ac (21,200 ha) and encompassed
all BLM management areas containing Astragalus magdalenae var.
peirsonii. In 2007, the BLM estimated the population size as 293,102
plants, or 14.2 plants/ac (35/ha), for portions of the Gecko, AMA and
Ogilby management areas, with an effective area of 20,692 ac (8,374 ha)
(Willoughby 2007, Table 5). However, the precision of the 2006 and 2007
population estimates was poor due to the low numbers of plants sampled
and their spatial variability (Willoughby 2006, p. vi; 2007, p. 11).
The disparity among these three survey methods and the data
collected make it difficult to assess the Astragalus magdalenae var.
peirsonii population. As presented in Table 1 below, the 2005 survey
conducted by BLM is the most extensive and precise effort to determine
overall population abundance and distribution. The amount of data
gathered in 2005 was the result of an exceptionally good rainfall year
and an extraordinary monitoring effort, and represents the best
estimate of the potential population and extent of habitat for A.
magdalenae var. peirsonii. The year 2006 was exceptionally dry, with no
reported A. magdalenae var. peirsonii germination and few surviving
plants from 2005. The 2007 rainfall pattern was not evenly distributed
throughout the dunes and contributed to the spatial variability that
yielded poor precision for the population estimates of that year
(Willoughby 2007, pp. 6-7 and Table 2).
Table 1.--Abundance Values Submitted for A. Magdalenae var. Peirsonii in the Algodones Dunes in 14 Unpublished Reports
--------------------------------------------------------------------------------------------------------------------------------------------------------
No. plants Estimated x8 abundance
Year Surveyor counted population class No. samples Effective area
--------------------------------------------------------------------------------------------------------------------------------------------------------
1977............................ WESTEC............ N/A N/A 4.3 1,611 167,800 ac (67,900 ha).
1998............................ BLM \1\........... 5,064 N/A 6.3 542 167,800 ac (67,900 ha).
1999............................ BLM \1\........... 942 N/A 2.8 542 167,800 ac (67,900 ha).
2000............................ BLM \1\........... 86 N/A 1.1 542 167,800 ac (67,900 ha).
2001............................ BLM \1\........... 5,930 N/A 4.7 542 167,800 ac (67,900 ha).
2002............................ BLM \1\........... 2,297 N/A 3.3 542 167,800 ac (67,900 ha).
2001............................ Phillips \2\...... \3\ 71,926 N/A .............. 127 35,000 ac (14,165 ha).
2001............................ Phillips \2\...... 30,771 N/A .............. 25 138 ac (56 ha).
2003............................ Phillips \2\...... 33,202 N/A .............. 25 138 ac (56 ha).
2005............................ Phillips \2\...... 77,922 \4\ 173,328 .............. 25 138 ac (56 ha).
2006............................ Phillips \2\...... 1,233 \4\ 2,035 .............. 25 138 ac (56 ha).
2004............................ BLM \1\........... 25,798 286,374 .............. 135 53,000 ac (21,200 ha).
2005............................ BLM \1\........... 739,805 1,831,076 .............. 510 53,000 ac (21,200 ha).
2006............................ BLM \1\........... 761 83,451 .............. 775 53,000 ac (21,200 ha).
2007............................ BLM \1\........... 1,435 293,102 .............. 735 20,692 ac (8,374 ha).
--------------------------------------------------------------------------------------------------------------------------------------------------------
\1\ BLM reports cited as Willoughby.
\2\ Phillips reports cited as Phillips et al. or Phillips and Kennedy.
\3\ Reconnaissance of unspecified area.
\4\ Estimated population for 60 specific sample sites.
As illustrated in Table 1, two substantial issues are associated
with the body of survey work for Astragalus magdalenae var. peirsonii.
These two issues are (1) comparison of BLM data with WESTEC data and
(2)
[[Page 41012]]
interpretation of abundance values. Each issue is discussed below.
Comparison of BLM data with WESTEC data. The first issue concerns
the early surveys conducted between 1977 and 2002. Although mean
abundance class values were calculated from sample transects across the
entire dunes, class values were only comparable between years. It is
not appropriate to compare these class values with more recent or finer
scale data that is based on counts of plants (rather than abundance
classes). Willoughby (2000, p. 7) recognized that the 1998 BLM data,
and the data BLM collected through 2002, might not be directly
comparable to the 1977 (WESTEC 1977) data (Willoughby 2000, p. 7).
Therefore, he (Willoughby 2000, p. 34, and reiterated 2001, p. 28)
addressed the limitations of the monitoring data to that point in time
by recognizing that statistically significant sample values between
1977 and 1998 were not ``proof'' that Astragalus magdalenae var.
peirsonii had increased significantly. Our assessment of the data
indicates that the density classes of WESTEC (1977) and BLM (Willoughby
1998-2002) are qualitative and are not based on particular numbers of
individual plants but rather on the apparent visual density of plants
as a feature of the landscape. These reports (WESTEC 1977 and BLM 1998-
2002) do not include quantitative measures of density, based upon
counts of numbers of plants per unit area. We are not aware of any
quantitative measures of density for A. magdalenae var. peirsonii for
the years included in these reports.
Although Willoughby (2000, p. 7) noted the limitations of the
WESTEC (1977) data, he converted the qualitative measures into
quantitative measures for comparison with the BLM survey data in an
attempt to assess abundance among years. The magnitude of non-sampling
error (subjective errors arising from activities other than sampling or
measuring) in the WESTEC (1977) study, however, makes comparison with
the BLM data problematic (L. Ball USFWS in litt. 2003, p. 2, comment
for ASA (2001) petition). In addition, peer reviewers also commented on
the inappropriateness of comparisons between the BLM study results and
those of WESTEC (1977). In his peer review comments for the ASA (2001)
petition, Pavlik (in litt. 2003, p. 3, comment for ASA (2001) petition)
stated that ``[a]ny attempt to establish population trends by
comparison to the 1977 WESTEC study should be rejected because there is
no objective way to replicate with certainty WESTEC's vague and highly
subjective relative abundance codes'' (see WESTEC 1977, Table 2-3).
Climatic variability should also be considered when comparing the
1977 WESTEC study with more recent surveys. Pavlik (in litt. 2003, p.
4, comment for ASA (2001) petition) stated that rainfall during the
October through March period, most critical for germination, was less
in 1977 than in 1998, and, therefore, if more plants were present in
1998, it could have been due to increased rainfall rather than lack of
OHV impacts. He noted that this was stated explicitly in Willoughby
(2000, p. 34), but not in ASA (2001). In her peer review, Bowers (in
litt. 2006) noted that the updated petition (ASA 2005, p. 36) stated
that despite increasing OHV traffic, Astragalus magdalenae var.
peirsonii rebounded after the 1977 survey made by WESTEC. Bowers (in
litt. 2006, pp. 6-7) stated that:
at the time of the 1977 surveys, when PMV [A. magdalenae var.
peirsonii] was apparently at a low ebb, the southwestern United
States had only recently emerged from a long and serious drought
[see Swetnam and Betancourt 1998, p. 3131]. This suggests that under
relatively light OHV use, PMV is sensitive to severe drought. The
post-1977 increase in PMV occurred during the wettest two decades in
the twentieth century. In fact, the period from 1976 to 1998 was
among the wettest during the past one thousand years [see Swetnam
and Betancourt 1998, pp. 3140-3141; Willoughby 2006, Figure 3]. This
suggests that PMV thrived under increasing OHV pressure only because
climate favored regeneration. I cannot emphasize too strongly that
our belief in the resilience of this species is biased by unusually
favorable conditions for reproduction in recent years.
Kalisz and McPeet (1993, p. 319) note that multiple years of poor
conditions magnify this impact on population growth rates and the
dormant seed bank.
Therefore, the information available to us indicates that using the
WESTEC data, in comparison with other data, to assess abundance trends
in Astragalus magdalenae var. peirsonii is inappropriate. This suggests
that claims of trends of population increases based on comparisons of
BLM surveys (Willoughby 2000, 2001, and 2004) and the WESTEC survey
(1977) are not supportable, both because the surveys are not comparable
due to differences in methodology and because of climatic variability
between the years surveyed (i.e., any increases observed could be due
to increases in rainfall in later years rather than to actual increases
in numbers of plants). At the time of listing in 1998, the available
data (WESTEC 1977) indicated that A. magdalenae var. peirsonii was not
abundant within the Algodones Dunes, and an analysis of threats to the
species, in light of the species' life history traits, indicated that
listing the species as threatened was warranted.
Interpretation of abundance values. The second issue associated
with the survey work for Astragalus magdalenae var. peirsonii concerns
the abundance values reported from 2001 through 2006 by Phillips et al.
(2001), Phillips and Kennedy (2003, 2005, and 2006), and Willoughby
(2005a, 2005b, 2006, and 2007). The Phillips reports (Phillips et al.
(2001), Phillips and Kennedy (2003, 2005, and 2006)) and the BLM
reports (Willoughby (2005a, 2005b, 2006, and 2007)) used different
sampling protocols and estimation procedures. Because the methodologies
for these surveys differed from one another, caution should be used in
comparing them. Phillips et al.'s (2001) reconnaissance covered an
unspecified large area, but observations were reported from only 127
locations (Phillips et al. (2001, Appendix A). The 25 monitoring sites
established by Phillips and Kennedy (2001, 2002) were subjectively
selected for A. magdalenae var. peirsonii presence and not designed to
estimate abundance beyond the extent of the 138-ac (56-ha) sampling
area (Phillips and Kennedy 2002, p. 10). In contrast, the BLM surveys
were designed to estimate the standing A. magdalenae var. peirsonii
population (Willoughby 2005a, 2005b, 2006) throughout its entire range
in the dunes. Data were compiled in 25-by-25-meter cells derived from
transects totaling 577 mi (930 km) in 2004 (Willoughby 2005a, Table 1)
and 1,922 mi (3,095 km) in 2005 (Willoughby 2005b, Table 1), covering
the full length of the dunes and sampling all micro-habitats along each
transect (Willoughby 2005b, pp. 1-3).
According to the updated petition, the survey method used by
Phillips et al. (2001) ``eliminated the need for a sampling methodology
and statistical extrapolations'' because they counted every plant
encountered (ASA 2005, p. 41; Phillips et al. 2001, p. 3). At each
sample site, ``relatively dense'' clusters that best fit the
requirements of the sampling design were systematically sampled
(Phillips and Kennedy 2002, p. 10). In assessing the Phillips survey
efforts conducted to date, we focused on Phillips et al. (2001) because
this study was the basis for all subsequent field studies conducted by
Phillips and Kennedy. Monitoring sites which would be sampled
repeatedly over several years (Phillips and Kennedy 2002 through 2006)
were randomly chosen from 60 areas designated as sites in Phillips et
al. (2001). Twenty-five sites (40 percent of designated sites) were
selected.
[[Page 41013]]
As routinely cautioned against in standard sampling or monitoring
protocols (e.g., Elzinga et al. 1998, p. 64; Thompson et al. 1998, p.
12; Morrison et al. 2002, pp. 62-63; Ott and Longnecker 2001, p. 21),
or protocols for assessing demographics and censusing rare plants
(e.g., Falk and Holsinger 1991, pp. 225-238; Pavlik and Barbour 1988,
pp. 218-224; others as noted in Porter in litt. 2003, p. 1, comment for
ASA (2001) petition), this sampling methodology is subject to
introduced selection error. Kalisz (in litt. 2006, p. 6), Converse (in
litt. 2006, pp. 2-4), and Porter (in litt. 2003, pp. 1-5, comment for
ASA (2001) petition) commented in their peer reviews on the
inappropriate methodology used by Phillips and Kennedy. Specifically,
Converse (in litt. 2006, p. 4) noted that Phillips and Kennedy (2005)
calculated plant density ``not for a pre-selected area, but for areas
that were found to have concentrated numbers of plants, thus leading to
seriously inflated estimates.'' In fact, density values reported by
Phillips and Kennedy (2005) and Willoughby (2005b) are consistent with
the concern that Phillips and Kennedy's estimates may be inflated.
Phillips and Kennedy (2005, p. 11) estimated plant densities of 0.18 to
0.78 plants per square meter (1,800 to 7,800 plants per hectare or 728
to 3,156 plants per acre) as compared to Willoughby's (2005b, p. v.)
2005 estimates of 9 to 53 plants per acre (22 to 132 plants/ha). Only
0.1 percent of the 37,169 cells sampled by BLM in 2004 had a density
equal to or greater than 1,800 plants/ha (USFWS 2006a), and 1 percent
of the 123,488 cells sampled by BLM in 2005 contained a density equal
to or greater than 1,800 plants/ha (USFWS 2006b).
The updated petition asserted that plant counts conducted from 1998
to 2005 by Phillips and Kennedy and BLM confirm that the Imperial Sand
Dunes support more than 100,000 individual Astragalus magdalenae var.
peirsonii and confirm that A. magdalenae var. peirsonii is abundant and
thriving throughout the dunes (ASA 2005, p. 46). As noted above, there
are weaknesses in the sampling methodology used in Phillips and Kennedy
(2002, 2003, 2004, 2005, and 2006). These weaknesses affect the
reliability of the estimates presented in the Phillips and Kennedy
reports (2002, 2003, 2004, 2005, and 2006). However, we do not disagree
with the updated petition that the Imperial Sand Dunes can support
100,000 or more individual A. magdalenae var. peirsonii plants. The BLM
surveys of 2005 confirm this point (USFWS 2006b, Table 2; Willoughby
2005, p. 25).
Distribution of Astragalus magdalenae var. peirsonii in the
Algodones Dunes. The updated petition (ASA 2005, p. 23) cites Phillips
et al. (2001, p. 13) in qualitatively assessing the presence and
abundance of Astragalus magdalenae var. peirsonii in open versus closed
areas. Phillips et al. (2001, p. 4) stated that a ``general
reconnaissance of virtually all portions of the dunes outside of the
administrative closures and wilderness area was performed'' and that
``specific survey areas were selected and intensively searched for
occurrences.'' Phillips et al. (2001, p. 13), in this reconnaissance,
state that they observed A. magdalenae var. peirsonii colonies that
``appeared to be similar in number and abundance'' in both the open and
closed areas of the dunes. However, this statement is inconsistent with
other portions of the report. For example, the report also states that
the ``area with dense occurrences in the large central closure was
perhaps twice the size of the area with sites south of the closure and
north of I-8. Although no counts were possible from the helicopter,
many sites with large numbers of plants were observed within the
closure.'' Phillips and Kennedy (2005, p. 7) also stated that the
purpose of the 2001 surveys ``was to locate as many occurrences of the
subject plants as possible, and to completely census and document
reproductive and habitat data from every area in the dune system in
which they were found,'' but noted that ``mappable concentrations of
plants were noted * * * in less than 25% of the dunes proper''
(Phillips and Kennedy 2002, p. 17). Converse (in litt. 2006, p. 3)
noted that some areas were not searched as intensively as others. In
sum, it appears that all extant plants were probably not found within
the large expanse of the dunes, that A. magdalenae var. peirsonii was
unevenly distributed in the dunes, and that large concentrations of A.
magdalenae var. peirsonii were noticeable within the areas closed to
OHV use.
Survey efforts to date have clarified the uneven distribution of A.
magdalenae var. peirsonii throughout the dunes. Even in the best of
years, BLM observed A. magdalenae var. peirsonii in just 21 percent of
the sample cells (USFWS 2006b, Table 1). In that year, 2005, half the
observed A. magdalenae var. peirsonii, approximately 370,000 plants,
occurred in 0.7 percent of the survey area (USFWS 2006b, Table 2) or
about 145 acres (58 ha). Just over 11 percent of the survey area, or 54
percent of the occupied area, contained a trace density of plants (less
than 39 plants/ac (100/ha)) (USFWS 2006b, p. 3). Further, the Service
conducted a Chi-square analysis of BLM's 2005 data which revealed that
the odds of finding A. magdalenae var. peirsonii in areas closed to OHV
activity was 2.63 times greater than finding it in areas open to OHVs
(USFWS 2006b, pp. 3-4). Phillips and Kennedy's 2005 (2005, Appendix A)
and 2006 (2006, p. 8) reports further illustrate the fact that dense
concentrations of plants produce large quantities of seed pods, which
can, in turn, lead to high seed production estimates and high plant
persistence in localized areas.
Astragalus magdalenae var. peirsonii exhibits high variability in
density throughout the dunes, but density is highest in the southern
half of the dunes (Willoughby 2005, Table 4; USFWS 2006b, Tables 1 and
2, Map 1). Phillips et al. (2001) established 19 of their 25 monitoring
sites in close proximity to areas with high plant density (USFWS 2006b,
Map 2). The difference between the current BLM studies and those of
Phillips and Kennedy is one of detection rate. BLM systematically
sampled the entire dunes and reported a detection rate of 0.21 (A.
magdalenae var. peirsonii detected in 21 percent of the sample cells)
in the best of years (USFWS 2006b, Table 1). Phillips and Kennedy
systematically sampled areas selected for plant density yet can neither
calculate nor report a rate of detection.
Phillips and Kennedy (2002, p. 10) observed that 70 to 75 percent
of the dunes is not suitable habitat for A. magdalenae var. peirsonii.
This observation closely corresponds to the 79 percent of unoccupied
cells sampled by BLM and calculated by the Service (USFWS 2006b, Table
1) for 2005. As noted above, 11 percent of the area surveyed by BLM in
2005 contained a trace density of A. magdalenae var. peirsonii,
suggesting that these areas are marginal habitat that supported plants
due to the favorable conditions of 2005. Therefore, optimal habitat for
A. magdalenae var. peirsonii may be substantially less than the 21
percent reported (USFWS 2006b). Considering that A. magdalenae var.
peirsonii only occurs in the United States within the Algodones Dunes,
and only within a small percentage of the dunes, it is a rare plant.
Astragalus magdalenae var. peirsonii is a relatively rare plant as
further illustrated by comparison of its abundance and density to other
psammophytic (dune loving) plants. The State endangered Helianthus
niveus ssp. tephrodes (Algodones Dunes
[[Page 41014]]
sunflower), a psammophytic plant with closely parallel distribution to
A. magdalenae var. peirsonii, was more abundant than A. magdalenae var.
peirsonii in nearly all years surveyed (Willoughby 2004, p. 36;
Willoughby 2005a, Table 2-1). Pavlik (in litt. 2006) commented on plant
densities for common desert Astragalus and herbs. As noted by Rundel
and Gibson (1996, Table 5.11), density for three Astragalus taxa in the
Mojave Desert ranged from 400 to 1,200 plants per acre (1,000 to 3,000
plants/ha). Pavlik (in litt. 2006, p. 2) stated that ``if any of the
densities of established plants of common species * * * were multiplied
by the size of their geographic ranges, the total populations would be
on the order of 10\8\ to 10\10\.'' Bowers (1996) also found similar
plant densities for psammophytic dune plants in the Sierra del Rosario
Dunes of northern Sonora, Mexico, only 60 miles (100 km) away from the
Algodones Dunes and with a similar climate. Density of four annual
plant taxa ranged from 1,170 to 11,600 plants/ac (2,900 to 28,700
plants/ha) and for three perennial plants ranged from 5,000 to 6,200
plants/ac (12,500 to 15,400 plants/ha) (Bowers 1996, Table 2).
Astragalus magdalenae var. peirsonii, with a density of 9 to 53 plants/
ac (22 to 132 plants/ha), is 2 to 4 orders of magnitude lower than
other common desert and dunes plants of the California desert. By even
a qualitative comparison with data collected by other researchers, A.
magdalenae var. peirsonii is quite rare relative to other species and
in its spatial distribution in the dune landscape.
In summary, Astragalus magdalenae var. peirsonii is restricted to
one area within the United States with a comparatively lower density
than other dune species, with high variability in population size and
density, climate, spatial distribution, and area occupied. The
different population estimates presented in Table 1 above are valid in
and of themselves but cannot be compared to one another due to
differences in scale and methodology. Because of the differences
between the total number of samples and the total area sampled, we
recognize the recent BLM surveys as the most informative population
estimates for Astragalus magdalenae var. peirsonii. The work of
Phillips and Kennedy has been valuable in providing information on
various parameters of A. magdalenae var. peirsonii life history, but
cannot be used to support the assertions of the updated petition.
Phillips and Kennedy's population estimates are appropriate only in the
areas of their limited surveys, making it difficult to use their
estimates to predict overall population health, trend, or stability. As
the evidence suggests in Table 1, the size of the reproductive
population of A. magdalenae var. peirsonii varies widely among all
years surveyed and varies in density across the dunes (Willoughby 2005,
Appendix 1; USFWS 2006b, Map 1). We expect these natural annual and
spatial variations will continue and, therefore, detecting overall
trends will be difficult for this species.
Seed Production and Seed Bank Dynamics
As described above in the Background section, many annual and
short-lived perennial plants have a substantial soil seed bank. This
life-history trait complicates assessment of viability for these
species. When seed banks are important features of the demography of a
species, census and demographic information for adult populations may
mislead us about population viability. Understanding the seed bank
would help us better assess the long-term viability of a species.
However, seed banks are complex and difficult to quantify (Doak et al.
2002, pp. 312, 317; Given 1994, pp. 66-67).
Phillips and Kennedy (i.e., Phillips and Kennedy 2006, p. 10) and
the updated petition (i.e., ASA 2005, p. 44) emphasize the importance
of understanding the seed bank to understanding the status of
Astragalus magdalenae var. peirsonii. However, the updated petition
seems to confuse the number of seeds produced (i.e., fecundity) with
the number of seeds in the seed bank. In fact, the updated petition
appears to equate seed production with recovery (ASA 2005, pp. 4-6).
For example, Phillips and Kennedy (2002, p. 28) estimated seed
production on their 25 survey sites at approximately 2.5 million seeds.
However, they erroneously refer to estimated seed production as the
seed bank (Phillips and Kennedy 2002, p. 30; 2003, pp. 13, 21; 2004, p.
16; 2005, pp. 16-17). Lincoln et al. (1993, p. 223) define a soil seed
bank as ``the store of dormant seed buried in soil'' whereas fecundity
is defined as ``the potential reproductive capacity of an organism or
population, measured by the number of gametes or asexual propagules''
(Lincoln et al. 1993, p. 93).
Phillips and Kennedy (2005, Table 6) emphasize that a high seed
estimate is, in and of itself, enough to ensure stability. Pavlik (in
litt. 2006, p. 3), in his peer review, commented that this is incorrect
``knowing what we know about the high rates of seed mortality observed
in other rare plants.'' In her peer review, Bowers (in litt. 2006, p.
8) stated that ``multiplying average fecundity per plant by number of
plants in a sample or population yields an estimate for sample or
population fecundity. It is incorrect to substitute fecundity for seed-
bank size.'' Phillips and Kennedy do not estimate the size of the
persistent seed bank (Baskin and Baskin 2001, pp. 141-143) but rather
attempt to assess the potential seed bank, and therefore population
size, based on an estimated reproductive rate where seed pod production
roughly equals reproductive stability.
In addition, Phillips and Kennedy (2002-2006) compound their
sampling bias discussed above into hypothetical seed production values.
Annual seed production was calculated from a few sample sites and
extrapolated to 60 sites from the Phillips et al. (2001) reconnaissance
(Phillips and Kennedy 2006, p. 5). The average number of 171 seed pods
per plant, median of 113 per plant (Phillips and Kennedy 2002, p. 27),
was determined from only 10 plants (Phillips and Kennedy 2003, p. 12;
2004, p. 16). Phillips and Kennedy (2006, p. 9) calculated seed pod
production based on the assumption that 100 percent of perennial plants
are reproductive. They estimated an average 14 seeds per pod using
Barneby's (1964, p. 862) observation of 11 to 16 ovules per pod
(Phillips and Kennedy 2002, p. 27). Phillips and Kennedy's population
and seed production estimates are based on sample sites selected for
Astragalus magdalenae var. peirsonii abundance (Phillips and Kennedy
2001, p. 10), thereby introducing a sample bias to the stated estimate
of 2.5 to 5.7 million seeds.
In addition to this sample bias, the estimate is biased by the
assumption that most plants were reproductive. Kalisz (in litt. 2006,
p. 3) noted this problem in her peer review, stating that it was
incorrect to multiply the number of pods by the total number of plants
since many were seedlings. In fact, not all plants reproduce in a given
year, even when the climate is favorable for reproduction. Phillips and
Kennedy reported 45 percent of plants were reproductive in 2001
(Phillips and Kennedy 2003, Appendix A) and 63 percent were
reproductive in 2005 (Phillips and Kennedy 2005, Appendix A). The BLM
estimated that 75 percent of plants were reproductive in the 2005
surveys (Willoughby 2005, Table 4). In field surveys conducted in 2006,
a year with no germination where the only Astragalus magdalenae var.
peirsonii individuals alive in the Algodones Dunes were perennating
plants, the BLM reported that 68 percent of plants
[[Page 41015]]
were flowering adults (Willoughby 2006, p. vi). The Service reported 54
percent of plants as being reproductive in their study areas during
2006 (USFWS 2007, p. 13).
Furthermore, accurate estimates of seed production depend on
accurate estimates of the number of seed pods produced and the number
of seeds produced per pod. Median seed pod production, and therefore
mean seed production, likely varies annually. Using a mean production
value from only 10 plants at a single site will not yield an accurate
estimate for a population. Phillips and Kennedy reported that first-
year plants produce about five seed pods per plant and plants 1 year or
more in age produce large quantities of seed pods (Phillips and Kennedy
2002, p. 27). Phillips and Kennedy (2005, p. 17) stressed that plants
in their second year of growth and older produce many times more seed
pods than first-year plants. Whether median seed pod production on
older plants is 113 (Phillips and Kennedy 2002, p. 27) or 139 (USFWS
2007, p. 14), one of the limiting variables in Astragalus magdalenae
var. peirsonii stability is the ability or capability of the plant to
survive long enough to replenish the seed bank with enough seeds to
ensure continuing cohorts of plants.
To estimate seed production per pod, in 2005 field surveys, the
Service collected seed pods at random from plants throughout their
survey area in April 2005. In this study, 416 seed pods from 78 plants
were dissected and the undeveloped ovules were counted and separated
from mature seeds. We observed an average of 5.2 mature seeds per pod.
The total of mature seeds and undeveloped ovules (which are undeveloped
seeds) averaged 11.4 per pod (McKinney et al. 2006, p. 85). One pod
contained 15 mature seeds, while another pod contained 17 undeveloped
ovules and mature seeds, closely matching the account of Barneby (1964,
p. 862). The average of 5.2 mature seeds per pod is considerably less
than the 14 seed per pod value used by Phillips and Kennedy in their
seed production estimates (Phillips and Kennedy 2002, p. 27).
The BLM conducted a pilot seed bank study during spring 2007. This
pilot study randomly sampled 735 of the total cells sampled during the
spring 2005 surveys in the Gecko, Adaptive and Ogilby management areas.
All Astragalus magdalenae var. peirsonii seeds on the sand surface
within each cell were counted and then the cell was systematically
sampled with 49 cores to a depth of 4 inches (10.16 cm), counting
subsurface seed. BLM estimates a total of 53,200,000 seeds in the
Gecko, AMA, and Ogilby management areas in 2007, corresponding to a
density of 2,572 seeds/ac (6,356 seeds/ha) (Willoughby 2007, p. v,
Table 5).
Finally, it is important to note that only a small fraction of seed
produced in a given year survive to emerge as seedlings (Harper 1981,
pp. 111-147; Fenner 1985, pp. 57-71). Dormant seeds that persist in the
seed bank are subjected to many factors that may limit or preclude
their ability to germinate. These factors include predation from
animals or invertebrates, attack by microorganisms or fungi, habitat
altered by wind, flood or mechanical events, or senescence (Baskin and
Baskin 2001, pp. 149-160). After 5 years of greenhouse experiments,
Porter et al. (2005, p. 29) reported high germination rates and little
loss in seed viability. However, in artificial dune experiments the
germination rate dropped to 27 percent and only another 2 percent of
seeds germinated in the second season.
As noted above, Phillips and Kennedy (2005, p. 22) substantiated
that plants in their first season could produce seed, although on a few
seed-per-plant basis. The updated petition asserts that these first-
year plants contribute significantly to the seed bank and that the seed
bank is replenished within two or three growing seasons (ASA 2005, pp.
7-8). Phillips and Kennedy (2002, p. 27 and Table 7; 2003, pp. 20-21;
2004, p. 17) continually calculate the number of seeds produced per
pod, per plant, and per site and equate that production with
replacement of the seed bank. However, we know of no research or
studies that provide information specifically on the replacement rate
of A. magdalenae var. peirsonii to its seed bank or the seed bank
baseline size. Phillips and Kennedy's field observations were all
conducted in years with highly variable precipitation as compared to
the previous two decades (see Willoughby 2006, Figure 3), and their
studies cover a period with large variation in demographic rates.
However, seed banks are governed by demographic rates that can be
difficult to quantify over short study periods (Doak et al. 2002, p.
312). Willoughby (2007, p. 11) could not determine the seed bank age or
associate it with the very productive year of 2005, so it is difficult
to assign his estimate of 53,200,000 seeds as the seed bank baseline
for the 2007 study areas. Also, no analysis of seed viability was
conducted from the seeds sampled in spring 2007, further limiting the
assessment of the seed bank size. Willoughby (2007, p. 11) suggests
that seed bank sampling in a good rainfall year, after germination and
before seed set, would address the question of seed bank depletion and
seed bank age.
Kalisz and McPeek (1993, p. 319) emphasize that longer runs of bad
precipitation years can magnify the negative effects on populations.
Negative effects can include reduced germination, lower recruitment and
reproduction, and runs of bad years exceeding the seed viability time
in the seed bank. Because Phillips and Kennedy's (2002, p. 27 and Table
7; 2003, pp. 20-21; 2004, p. 17) estimates equate one seed produced
with one plant germinated and we have no information on the seed bank
baseline, their assertion that the seed bank is replaced within 2 or 3
growing seasons is speculative.
We agree with the updated petition (ASA 2005) that understanding
the soil seed bank is important to understanding the long-term
viability of Astragalus magdalenae var. peirsonii. However, for the
reasons stated above, we do not agree that the work of Phillips and
Kennedy (2002, 2003, 2004, and 2006) effectively elucidates the nature,
extent, and dynamics of the seed bank for A. magdalenae var. peirsonii
to the point that we fully understand the seed bank's contribution to
the long-term persistence of A. magdalenae var. peirsonii. We also do
not agree that these data provide evidence that A. magdalenae var.
peirsonii will continue to persist because of the extent and nature of
its seed bank. In fact, the information suggests that estimates of
plant persistence and reproduction based on the anecdotal observations
in the literature or single-year observations may not be accurate
predictors of the nature or dynamics of the seed bank. Evidence
suggests that not all plants (i.e., not 100 percent) reproduce in any
given year, that seed pod production may be as much as one-third less
than reported by Phillips and Kennedy, that seed production is as much
as two-thirds less than that reported by Phillips and Kennedy, that
only a small fraction of seeds may germinate from the persistent seed
bank, and that under managed conditions about one-quarter of seeds in
the wild may germinate. Phillips and Kennedy (2006, Table 3) did not
consider any of these variables in their seed bank estimates. These
variables and others (e.g., rate of seed mortality and aging, amount of
seed lost to predators (Elzinga et al. 1998, p. 284)) must be
considered for inclusion in models to estimate long-term persistence of
A. magdalenae var. peirsonii. Pavlik (in litt. 2003, p. 4, comment for
ASA (2001) petition) and Bowers (in litt. 2006, p. 9) noted that
[[Page 41016]]
Phillips and Kennedy have, however, begun to collect data valuable as
initial parameters for these models.
Summary of Factors Affecting the Species
Section 4 of the Act and its implementing regulations (50 CFR part
424) set forth the procedures for listing species, reclassifying
species, or removing species from listed status. ``Species'' is defined
by the Act as including any species or subspecies of fish or wildlife
or plants, and any distinct vertebrate population segment of fish or
wildlife that interbreeds when mature (16 U.S.C. 1532(16)). Once the
``species'' is determined we then evaluate whether that species may be
endangered or threatened because of one or more of the five factors
described in section 4(a)(1) of the Act. We must consider these same
five factors in delisting a species. We may delist a species according
to 50 CFR 424.11(d) if the best available scientific and commercial
data indicate that the species is neither endangered nor threatened for
one or more of the following reasons: (1) The species is extinct; (2)
the species has recovered and is no longer endangered or threatened; or
(3) the original scientific data used at the time the species was
classified were in error.
A recovered species is one that no longer meets the Act's
definition of threatened or endangered. Determining whether a species
is recovered requires consideration of the same five categories of
threats specified in section 4(a)(1) of the Act. For species that are
already listed as threatened or endangered, this analysis of threats is
an evaluation of both the threats currently facing the species and the
threats that are reasonably likely to affect the species in the
foreseeable future following the delisting or downlisting and the
removal or reduction of the Act's protections.
A species is ``endangered'' for purposes of the Act if it is in
danger of extinction throughout all or a ``significant portion of its
range'' and is ``threatened'' if it is likely to become endangered
within the foreseeable future throughout all or a ``significant portion
of its range.'' The word ``range'' in the significant portion of its
range phrase refers to the range in which the species currently exists.
For the purposes of this analysis, we will evaluate whether the
currently listed species, Astragalus magdalenae var. peirsonii, should
be considered threatened or endangered. Then we will consider whether
there are any portions of A. magdalenae var. peirsonii's range in which
the status of the species differs from that determined for the species
range-wide.
Merriam-Webster's Collegiate Dictionary defines ``foreseeable'' as
``being such as may be reasonably anticipated'' and ``lying within the
range for which forecasts are possible'' (Merriam-Webster 2001, p.
456). For the purposes of this finding, the ``foreseeable future'' is
the period of time over which events or effects reasonably can or
should be anticipated, or trends reasonably extrapolated. Habitat for
Astragalus magdalenae var. peirsonii in the United States is almost
entirely in public ownership and management at the BLM Imperial Sand
Dunes Recreation Area (ISDRA). Due to recent litigation, the specifics
of how the BLM will manage the ISDRA in the short term are unclear. As
described under ``A. The Present or Threatened Destruction,
Modification, or Curtailment of Its Habitat or Range,'' the current
Recreation Area Management Plan (RAMP) (BLM 2003a) is not being
implemented due to a court order, but is the most recent plan available
for analysis. At some point, BLM will implement a RAMP for the area,
but when that will occur is also unclear. However, based on past
management by BLM and the management direction for the ISDRA described
in the current RAMP, we can reasonably anticipate that BLM will
continue to manage habitat within the ISDRA in the long-term for
multiple use, including OHV recreation. In light of such long-term
management direction and the available data regarding impacts to A.
magdalenae var. peirsonii resulting from anticipated continued and
increased OHV use within the ISDRA, as analyzed below, we believe that
reliable predictions can be made concerning the future as it relates to
the status of A. magdalenae var. peirsonii.
In making this finding, we evaluated the best scientific and
commercial data available (including the updated petition and
associated documents (ASA 2005), our analysis (USFWS 2006a and 2006b)
of BLM's raw data for the 2004 and 2005 surveys (Willoughby 2005a and
2005b, respectively), field studies conducted by the Service (Groom et
al. 2007, USFWS 2007), the most recent reports by Phillips and Kennedy
(2005 and 2006), BLM (Willoughby 2005b and 2006), and McGrann and
McGrann (2005), and other information available to us) to determine
whether delisting Astragalus magdalenae var. peirsonii is warranted.
The following analysis examines the five factors described in section
4(a)(1) of the Act and those activities and conditions currently
affecting, or that are likely to affect, A. magdalenae var. peirsonii
within the foreseeable future.
A. The Present or Threatened Destruction, Modification, or Curtailment
of Its Habitat or Range
In the final rule listing Astragalus magdalenae var. peirsonii (63
FR 53596, pp. 53605-53606) and in our 12-month finding on the previous
petition to delist A. magdalenae var. peirsonii (69 FR 31523, pp.
31527-31529), we identified off-highway vehicle (OHV) use as a serious
threat to A. magdalenae var. peirsonii. We continue to consider such
activity, and the development associated with it, to present
significant threats to A. magdalenae var. peirsonii and its dune
habitat. The studies supporting this conclusion and the extent with
which A. magdalenae var. peirsonii is threatened by OHVs are discussed
below, as are probable effects of OHVs on seedling establishment, and
visitation patterns in the Algodones Dunes.
Studies on desert plants other than Astragalus magdalenae var.
peirsonii. Although few quantitative data are available, early studies
documented general OHV impacts on desert and psammophytic vegetation in
California. Bury et al. (1977, pp. 16-19, Fig. 11) compared eight
paired sites in the Mojave Desert in 1974 and 1975, examining the
impact of OHV use on creosote bush scrub and associated wildlife.
Pavlik (1979, p. 75-79) quantified the immediate physical effects of
direct contact with an OHV on the Eureka Dunes in Inyo County,
California. Luckenbach and Bury (1983, p. 280) in non-replicated
studies of paired plots along State Route 78 through the Algodones
Dunes, reported reduced numbers of herbaceous and perennial plants,
arthropods, lizards, and mammals between areas closed to entry (i.e.,
control plots) and those exposed to heavy OHV use. The results of these
studies indicated that OHV impacts were higher or had a greater effect
on habitat outside control plots. However, all of these studies were
limited in scope because they either observed impacts on a small number
of sample plants or the sample areas were limited in distribution.
Studies with information on OHV damage to Astragalus magdalenae
var. peirsonii. Several studies included data and/or observations
relevant to assessing OHV damage to A. magdalenae var. peirsonii.
McGrann and McGrann (2005) assessed OHV impacts in paired plots along
OHV closure boundaries. Phillips and his colleagues' reports (2001,
2003, and
[[Page 41017]]
2005) include estimations of numbers of plants damaged, likelihood of
OHVs avoiding plants, and resilience of plants to OHV impacts.
Willoughby (2005a, 2005b) included estimates of the numbers of plants
damaged in 2004 and 2005. Groom et al. (2007) followed the fates of
individual plants (some run over by OHVs and others not (i.e.,
``controls'')) throughout the growing season. Finally, a study
conducted by Service biologists as a follow-up to Groom et al. (2007)
compared survival of A. magdalenae var. peirsonii over the growing
season in areas open to OHVs with survival in areas closed to OHVs.
Each of these studies is discussed briefly below.
McGrann and McGrann (2005, pp. 67-69), used 42 matching pairs of
plots systematically distributed along closure boundaries in three
study areas of the Algodones Dunes to assess OHV impacts on Astragalus
magdalenae var. peirsonii. However, the results of this study were
inconclusive due to the low number of plants sampled, sampling period,
and climate. Only 19 plants were found among the 42 plots, and the
Buttercup study area was sampled very late in the season. Astragalus
magdalenae var. peirsonii densities were higher for small plants and
seedlings on control plots versus impact plots with more than 30 OHV
tracks per plot when all plots were pooled, but were not significant
for adult plants (McGrann and McGrann 2005, pp. 71-72). In plots with
fewer than 30 OHV tracks, 50 percent had higher overall plant density
than in the control plot.
Because of the transient nature of the surface structure of dunes,
most quantitative measures of OHV impacts are given in terms of numbers
of plants impacted. Phillips et al. (2001, p. 12) stated that only 667
plants observed in the areas open to OHVs showed signs of contact with
OHVs. Phillips and Kennedy (2003, p. 21) noted only 430 plants damaged
by OHVs during 2003. However, we find these values to be of limited use
for several reasons. First, both of these surveys occurred from March
to May 2001 and 2003, respectively, well after the peak holidays with
high dune visitation. Second, Phillips and Kennedy's damage reports
based on their monitoring sites represent only about 138 ac (56 ha). If
we extrapolate their data to Astragalus magdalenae var. peirsonii
habitat in the area open to OHV activity, approximately 4,709 ac (1,905
ha), the number of plants potentially impacted by OHVs could be more
than 10,000 plants, but we have no way of evaluating the accuracy of
this extrapolation. Third, Phillips et al. (2001, p. 12) noted that
signs of OHV effects are transitory, observing that ``as wind
obliterated the tracks there was no sign of any effect.'' Phillips and
Kennedy may be under estimating damage by assuming that the only direct
evidence of any ``effect'' is a tire track in the sand that can be
directly associated with a damaged plant. We assume that the wind will
also obliterate any evidence of damage to plants by blowing away broken
branches and burying broken stems in sand. Fourth, Phillips et al.
(2001) did not record whether these were one-time observations over the
survey days, or if damaged plants were tracked to prevent double-
counting of individuals.
In addition, Phillips et al. (2001, p. 12) suggested that the
number of damaged plants was minimal because OHV drivers avoid
vegetated basins, where Astragalus magdalenae var. peirsonii often
grows in proximity to shrubs, to prevent potential tire damage. The
authors provided no information on plants observed outside of bowls
with woody detritus, nor did they discuss the potential damage to
plants from four-wheel quads or motorcycles that can traverse woody
basins without damaging equipment. However, Phillips and Kennedy (2005,
p. 22) also observed that A. magdalenae var. peirsonii was more widely
distributed in 2005 compared with other years, ``with low density
occurrences often observed between sites where no plants'' were before.
This suggests that plants, at least in 2005, were not isolated to bowls
with woody vegetation and therefore were unprotected.
Phillips et al. (2001, p. 12) anecdotally observed that nearly all
plants that were run over were resilient and ``popped back up'' with no
damage to the stems or flowers and that ``as soon as the wind
obliterated the tracks, there was no sign of any effect.'' These
observations of impact and resilience were made without determining the
persistence or the productivity of the plants damaged. Additionally, no
follow-up visits were noted, and no measures of impact to the habitat,
description of type of damage, or effects on plant reproductive
capacity were provided.
Willoughby (2005a, pp. 13-14) reported that 731 plants exhibited
signs of OHV impact during the 2004 surveys, and more recently he
reported that 8,113 plants exhibited signs of OHV impact along the 2005
survey transects (Willoughby 2005b, p. 24). Both of these estimates,
731 and 8,113 plants, are from one-time observations along transect
surveys conducted during spring 2004 and 2005, respectively. In light
of the number of survey transects in spring 2005, we consider
Willoughby's (2005b, p. 24) estimate of 8,113 plants damaged by OHVs as
the best single-date, dunes-wide estimate available. Nonetheless, this
number was acquired from surveys conducted from mid-February through
April 2005, well after peak-use holiday weekends. All survey cells were
visited once during this time period. The estimate, 8,113 plants, does
not include plants likely impacted during the peak holiday weekends
prior to the surveys. We estimate that the number of plants impacted
could be 2 to 3 times larger when these holidays are factored in, based
on the number of peak-use days prior to the surveys, but we have no
means to evaluate the accuracy of this estimate.
Groom et al. (2007) is the first study to date to monitor
individual plant fates through a growing season. Astragalus magdalenae
var. peirsonii GPS (Global Positioning System) coordinates were
acquired on randomly selected plants marked in an experiment conducted
from February until June 2005. Some plants (i.e., ``treatment plants'')
in an area closed to OHV activity were purposefully struck with an OHV
and their reproductive capacity and fate were tracked with repeated
monthly visits. Results indicate that plants with canopies less than 18
inches (0.5 m) had a 33 percent lower survival rate than plants in the
control group that were not struck (Groom et al. 2007, pp. 128-130).
Service biologists continued to track survivorship in a follow-up study
conducted from December 2005 until June 2006. No germination occurred
during the 2006 growing season, indicating that all live plants
encountered were greater than 1-year old. In this study, GPS
coordinates were acquired for A. magdalenae var. peirsonii plants in
two 618-ac (250-ha) study areas, one in an OHV-open area and one in an
OHV-closed area. Every plant was revisited monthly to monitor health,
reproductive state, biometrics, and seed pod production. Plants in the
OHV-open area were 20 percent less likely to survive the entire study
period than plants in the OHV-closed area (USFWS 2007, p. 14).
While the observational data reported by Phillips and Kennedy and
BLM shed some light on OHV impacts to Astragalus magdalenae var.
peirsonii, the results are of limited value. Groom et al. (2007) and
the follow-up Service study have three principal advantages over the
observational data. First, these studies were designed to test specific
hypotheses regarding plant survival, using dune bowls or individual
plants
[[Page 41018]]
that were randomly selected within each study area. Second, in both
years, these studies documented plant fates through the season, rather
than a single observation late in the season. Third, the 2006 study
(USFWS 2007) covered all major holiday weekends except Thanksgiving,
extending the time period of the study to correspond with OHV use in
the dunes. The data including major holiday periods more accurately
reflects plant fate because the risk to plants in the open area is
dependent upon dune use patterns.
Most of the studies, and in particular Groom et al. (2007) and the
follow-up Service study (USFWS 2007), indicate that Astragalus
magdalenae var. peirsonii plants can be damaged by OHV activity. In
fact, the observation by Phillips et al. (2001, p. 12) that ``the
occurrence of dune plants and heavy use areas for vehicles is, to a
large extent, mutually exclusive,'' describes similar findings by
Willoughby (2000, p. 36), WESTEC (1977, pp. 131-134), Luckenbach and
Bury (1983, p. 280), ECOS (1990, p. 81), and McGrann and McGrann (2005,
pp. 69-76). While little or no documentation exists of the graded
effects of medium- and low-use areas for vehicles, by the time the
vehicle use level can be described as ``heavy,'' the area is generally
devoid of plants. The exact process is not understood, but we postulate
that either repeated depletion of pre-flowering seedlings depletes the
seed bank, elimination of standing seed-producing plants diminishes and
eventually extinguishes input to the seed bank, or untimely or
excessive scarification of the seeds by the additional grinding actions
of sand moved by OHVs causes seeds to desiccate. The conclusion that
the petitioners reach suggesting OHVs are not damaging the A.
magdalenae var. peirsonii population originated in Phillips et al.
(2001) (see discussion in Distribution of Astragalus magdalenae var.
peirsonii in the Algodones Dunes section). This conclusion is based on
a reconnaissance of the dunes that assessed presence and abundance of
A. magdalenae var. peirsonii in a general way in open and closed areas.
It was not designed to determine whether OHVs damage A. magdalenae var.
peirsonii, and it is internally inconsistent on whether differences in
presence and abundance were observed in open and closed areas. If
presence and abundance of A. magdalenae var. peirsonii were similar in
open and closed areas, it would suggest that OHVs may not be affecting
abundance. However, the Service's analysis of BLM's 2005 data indicates
that the petitioner's assertion is incorrect (USFWS 2006b, pp. 3-4).
Finally, Willoughby (2007, p. 9) concludes that ``the closed areas of
the Gecko and Ogilby MAs have larger seed banks than the open areas.''
Seedling establishment. In addition, the coincidence of timing of
seedling establishment and the cooler months preferred by OHV
enthusiasts increases the susceptibility of Astragalus magdalenae var.
peirsonii to impacts from OHVs (Romspert and Burk 1979, pp. 29-30). The
period of plant sensitivity, approximately late October to late
February, includes seed germination and emergence (Barneby 1964, p.
862; Phillips and Kennedy 2002, p. 29). Aside from the direct crushing
of the delicate seedlings, OHVs in close proximity to the seedlings may
indirectly affect germinating seedlings by accelerating soil
desiccation that can result in root desiccation (Harper 1981, pp. 116-
117; Lathrop and Rowlands 1983, p. 144). The roots of A. magdalenae
var. peirsonii seedlings are especially sensitive to drying out if the
plants or sand surface are disturbed. Seedling death may result from
both types of impacts. Seedlings damaged but not killed may produce
fewer flowers and seeds than undamaged seedlings leading to a gradual
diminishment of the seed bank (Pavlik 1979, p. 76). This period of
sensitivity directly overlaps five of the six visitation peaks to the
Algodones Dunes, including Halloween, Thanksgiving, New Years Day,
Martin Luther King Day, and Presidents' Day (BLM 2003a, pp. 89, 201).
When Easter weekend is included, all holiday weekends, about 27 days,
account for 50 percent of annual visitation to the Dunes, with the
remaining 50 percent occurring on non-holiday weekends between October
and May (BLM 2003a, pp. 89, 201).
Visitation patterns. Since we listed Astragalus magdalenae var.
peirsonii, visitation by recreational users to the ISDRA has continued
to increase (BLM 2003b, p. 25; BLM 2006a) and has outpaced previous
projections (BLM 1987, Table 6). The updated petition (ASA 2005) did
not address visitor use patterns or increases relative to the
distribution of A. magdalenae var. peirsonii. The total number of
visitors to the dunes in 2006 (BLM 2006a) has nearly quadrupled from
1995 (BLM 2003b, p. 25). Based on figures from BLM, visitor use
increased by 69 percent from fiscal year 2000 (BLM 2003a, p. 237) to
fiscal year 2006 (BLM 2006a). Specifically, BLM recorded 867,753
visitor use days in 2000 (BLM 2003a, p. 237) and 1,464,580 in 2006 (BLM
2006a). Visitor use was up an additional 5 percent in fiscal year 2006
over fiscal year 2005 (BLM 2006a) despite a court-ordered closure of 29
percent of the ISDRA and claims that high gas prices would reduce
visitation, and was up slightly in fiscal year 2007 over fiscal year
2006 (BLM 2007). Visitor use is now more than 3 percent over the
projected estimate for 2012/2013 (BLM 1987, p. 15; 2003a, p. 237;
2006a). User groups are advocating for building as many camping pads as
possible until ``over a span of time 100 percent of both sides of
[Gecko] road would be camping pads'' in the Gecko Management Area (ASA
2002, p. 4). We conclude that visitor use in the Algodones Dunes is
likely to continue to increase.
The BLM has attempted to assess OHV impact areas on the dunes in 2
separate analyses. A vehicle track map (Willoughby 2000, Map 24) along
selected transects of the Algodones Dunes on Easter weekend 1998 showed
that considerable areas of potential habitat have been impacted. In a
more recent study, a randomized sample of 775 survey cells occupied by
Astragalus magdalenae var. peirsonii in 2005 were selected and analyzed
from digital aerial photographs acquired on Presidents' Day weekend in
2006 (Willoughby 2006, p. 3). The results indicate a slight negative
relationship between the logarithm (a common statistical transformation
of data) total number of A. magdalenae var. peirsonii plants and the
density of OHV tracks, but this relationship was not statistically
significant (P = 0.069) (Willoughby 2006, p. 10, Figure 12). The
results of both of these analyses were inconclusive because on-the-
ground counts of plants coincident with the vehicle-track mapped areas
were not performed and cumulative impacts to standing plants, seed
banks, or habitat cannot be estimated; whereas the studies of Groom et
al. (2007) and USFWS (2007) carefully monitored the fates of individual
plants damaged by OHVs or in high OHV-use areas.
Though a court order continues to require that BLM maintain 49,300
ac (19,950 ha) of temporary vehicle closures within five selected areas
in the ISDRA, BLM's 2003 Recreation Area Management Plan (RAMP) (2003a,
pp. 37-78) proposed opening to OHV use (to various extents) all
temporary closures in the dunes. Although this plan is not currently
being implemented, it is the most recent plan available for analysis.
Under this plan, the 27,700-ac (11,200-ha) North Algodones Dunes
Wilderness (Wilderness) would continue to be closed to OHV use.
However, less than 9 percent of the U.S. population of
[[Page 41019]]
Astragalus magdalenae var. peirsonii occurs within the Wilderness.
Although some areas supporting A. magdalenae var. peirsonii are remote,
technological advances, such as a fully implemented GPS navigation
system (USDoD 2005, p. 2-2), affordable GPS units and cell phones, and
OHVs with greater range, have removed the obstacles to OHV users to
penetrate further into the dunes (ASA 2006). Thus, well-equipped
vehicles can now travel farther on a tank of gas and are less likely to
get lost in the featureless expanse of the dunes, expanding potential
OHV impacts into areas that once inhibited access. If the court order
is lifted and the temporary closures are reopened to OHV activity,
adverse effects to A. magdalenae var. peirsonii populations within the
U.S. will increase.
If the court order were to be lifted, and BLM's 2003 RAMP
implemented, all areas in the Algodones Dunes with Astragalus
magdalenae var. peirsonii, except the Wilderness area, would be open to
some level of OHV use. Sixty-six percent of the U.S. population of A.
magdalenae var. peirsonii is located in the temporary closures (USFWS
2006b, Table 2), 9 percent is in the Wilderness area, and the remaining
25 percent in areas open to OHV use. Currently, the odds of finding A.
magdalenae var. peirsonii in areas closed to OHVs are 2.6 times greater
than in areas open to OHV use (USFWS 2006b, pp. 3-4). Evidence
indicates that 20 percent of the population occurring in areas open to
OHV use will not survive the entire growing season (USFWS 2007, p. 14)
and that the chances of an average plant surviving an impact will be
reduced by 33 percent (Groom et al. 2007, pp. 128-130). If the
temporary closures were removed and visitor use was equivalent to that
now documented in current open areas throughout the dunes, it is
reasonable to expect that plant density of A. magdalenae var. peirsonii
would be reduced to the mean density level now recorded for the open
areas, 23 plants/ac (56/ha) (USFWS 2006a, p. 4). We estimate that, at
that density, the dunes-wide population would be reduced by
approximately 41 percent (Bartel in litt. 2007, p. 2). This predicted
reduction in the 2005 observed population for A. magdalenae var.
peirsonii in the ISDRA may overestimate the effects of OHVs because we
did not account for the minimization of impacts via BLM's
implementation of the adaptive management proposed for the Adaptive
Management Area (AMA) of the ISDRA, nor did we account for the distance
from camping areas or access points that likely would ameliorate or
attenuate the effects of OHV use. Conversely, the 41 percent figure may
underestimate the effects of OHVs because we did not account for the
increasing trend in OHV use in the Algodones Dunes. The AMA and Ogilby
temporary closures total 37,519 ac (15,184 ha) and contain more than 50
percent of the current A. magdalenae var. peirsonii population (USFWS
2006b, Table 2). Even in light of the potential problems with this
estimate, the best data indicates that reopening the temporary closure
areas in the dunes to OHV use may reduce the A. magdalenae var.
peirsonii population in these two management areas alone by 50 percent.
In addition, the areas of highest abundance are areas closest to, and
within easy access of, the sand highway (the main unpaved thoroughfare
between staging areas and large, recreational dunes or dune complexes)
(USFWS 2006b, Map 1).
We are confident that reopening the temporary closure areas in the
dunes to OHV use would increase the impact of OHVs on Astragalus
magdalenae var. peirsonii. However, we acknowledge that there is
uncertainty with respect to the future management of the area by the
BLM. BLM and the Service are currently working together to consider
options for future management of the Algodones Dunes and the potential
impacts of various scenarios on A. magdalenae var. peirsonii. It is
conceivable that future management decisions could provide protection
and management that would ameliorate threats to A. magdalenae var.
peirsonii to such an extent that we would consider proposing to delist
the species.
In summary, areas within the dunes subject to intensive OHV use
have a lower abundance of Astragalus magdalenae var. peirsonii while
plants within the interior portions of the dunes and within temporary
closure areas appear to have been less affected by OHV use. The updated
petition and associated documents report hundreds of plants detected
during relatively brief survey periods that were impacted by OHVs (ASA
2005). Repeat visits to marked plants attest to a lower survival rate
for plants struck by OHVs (Groom et al. 2007, pp. 128-130) and for
plants in open areas in general (USFWS 2007, p. 14). Thus, studies of
the effects of OHVs on A. magdalenae var. peirsonii (e.g., Groom et al.
2007), the reported absence of dune plants from areas of heavy OHV use,
the documented trends of increasing visitorship in the Algodones Dunes,
the potential for the lifting of the temporary closures, and the
uncertainty associated with future management of the ISDRA support the
conclusion that OHV use continues to pose a significant threat to A.
magdalenae var. peirsonii and its dune habitat in the foreseeable
future, and we can reliably predict that the impacts of continued and
increasing levels of OHV use anticipated to occur, particularly if A.
magdalenae var. peirsonii is no longer listed, would likely result in a
downward trend in the population until A. magdalenae var. peirsonii is
in danger of extinction.
B. Overutilization for Commercial, Recreational, Scientific, or
Educational Purposes
We do not have any data suggesting that Astragalus magdalenae var.
peirsonii is, or may be, overutilized for commercial, recreational,
scientific, or educational purposes.
C. Disease or Predation
Herbivory was reported for some Astragalus taxa in the final rule
listing A. magdalenae var. peirsonii. As part of a series of reports on
the natural history of A. magdalenae var. peirsonii, Porter (2003a, p.
4) noted the general poor health of adult plants and attributed it to
rodent and insect herbivory. Porter (2002a, p. 07862) reported ``nearly
ubiquitous'' harvesting of leaflets and young inflorescences by rodents
in A. magdalenae var. peirsonii populations. Most of the plants had
leaves, leaflets, or terminal portions of the stems removed, likely by
unidentified rodents that had left abundant tracks around A. magdalenae
var. peirsonii plants. Porter (2003a, p. 4) also had similar results in
2003. To the extent that rodents remove photosynthetic tissue and young
inflorescences, plants are likely to exhibit a loss of vigor and
reduction in reproductive output (i.e., seeds) as noted by Hulme (1994,
pp. 647-650). Indeed, Phillips and Kennedy (2002, p. 24) noted that
seed bank counts were lower in areas where they noted kangaroo rat
tracks and dens and suggested that this should be investigated.
Astragalus magdalenae var. peirsonii, with its large seeds, may be more
prone to seed predation than the observations reported by BLM or
Phillips and Kennedy (Hoffmann et al. 1995, pp. 203-205). Pavlik (in
litt. 2003, p. 5, comment for ASA (2001) petition) noted that rodents
may be a constant, long-term source of high seed mortality that could
dramatically reduce the seed bank.
Beetles, in the family Bruchidae, were reported to contribute to
the high mortality of seeds and reduced seed crop for Astragalus
magdalenae var. peirsonii by Romspert and Burk (1979, pp. 28-29).
Larvae of these beetles eat
[[Page 41020]]
the contents of the seeds before emerging as adults. Fruits collected
in April continued to release beetles into October (Romspert and Burk
1979, p. 29). Porter (2003a, p. 5) found between 45 and 86 percent of
the fruits on the few A. magdalenae var. peirsonii plants where he
could find fruits were infested with bruchid beetles. The range of
infested fruits was 0 to 29 percent for dispersed fruits on the ground.
Similarly, for another obligate dune plant, Astragalus lentiginosus
var. micans, Pavlik and Barbour (1985, p. 61) found that dispersed
fruits had about 66 percent of the seeds eaten or damaged by insect
larvae compared to 86 percent of the seeds in fruits still on the
plant. Also the number of undamaged seeds decreased by more than 60
percent between April and May, indicating that predation is highest at
dispersal time. The reduction of productivity of any given cohort of A.
magdalenae var. peirsonii from seed predation is unknown but may
locally be considerable in a given year. Seed predation has also been
reported to cause significant loss of ovules or seeds in Sidalcea
nelsoniana, a federally threatened perennial forb (Gisler and Mienke
1997, pp. 58-60), in Astragalus canadensis (Boe et al. 1989, pp. 514-
515), and in two other species of Astragalus (Green and Palmbald 1975,
pp. 1436-1437). As yet unidentified weevils were also observed to strip
the epidermis from the stems, which would affect the movement of food
and water in the plants (Porter 2003a, p. 4).
Available information suggests that rodent herbivory and seed
predation by insects, as noted above, may play a pivotal role in plant
viability in dune bowls (Hulme 1996, pp. 610-611). We do not believe
that natural herbivory, by itself, is likely to pose a direct threat to
the conservation of Astragalus magdalenae var. peirsonii. However,
although the total impact to annual recruitment has not been quantified
in the dunes, the additional loss or damage of seeds or seedlings
through natural herbivory could exacerbate or augment threats to A.
magdalenae var. peirsonii in the presence of other stressors such as
increasing OHV activity, especially when the damage from natural
herbivory potentially impacts 30 to 60 percent, or more, of the
standing population (Porter 2003a, pp. 4-5).
D. The Inadequacy of Existing Regulatory Mechanisms
The discussion of the lack of regulatory protections for Astragalus
magdalenae var. peirsonii by the State of California cited in the final
listing rule (63 FR 53596) is still accurate. Pursuant to the Native
Plant Protection Act (California Department of Fish and Game (CDFG)
Code) and the State Endangered Species Act (CESA), A. magdalenae var.
peirsonii was listed as endangered in 1979. Because this plant
primarily occurs on BLM-managed lands, provisions of CESA do not apply.
The BLM and CDFG developed a habitat management plan (HMP) in 1987 that
included provisions for monitoring transects every other year until
trends were established. However, little monitoring specific to
sensitive species was carried out by BLM prior to the listing of A.
magdalenae var. peirsonii. Since the listing, BLM and CDFG have been
conducting periodic monitoring for the rare plants on the Algodones
Dunes.
The updated petition indicates that Astragalus magdalenae var.
peirsonii has received ``adequate regulatory protection from BLM since
1977'' (ASA 2005, p. 49). This statement is based on the premise that
BLM can only manage human activities, and human activities do not
negatively impact A. magdalenae var. peirsonii. As indicated above in
Factor A, we disagree with this assertion because we conclude that OHV
use (i.e., human activity) is a significant threat to A. magdalenae
var. peirsonii. Given our conclusion that OHV activity is a threat to
A. magdalenae var. peirsonii, we note that BLM's management of OHV
activity can affect the magnitude of the threat from OHVs to the plant.
No assessment exists of the relative contribution of the portion of the
population present in the Wilderness (permanently closed) to the
persistence of A. magdalenae var. peirsonii. Less than 9 percent of A.
magdalenae var. peirsonii plants were observed in the Wilderness in
2005, and though the Wilderness is considered closed to OHV use,
indications of occasional illegal entry in the form of OHV tracks in
the area can be found on maps (Willoughby 2000, Map 24). Designation of
the Wilderness was one of the reasons cited in the final rule for
changing the proposed status from endangered to threatened (63 FR
53609). As stated in the final listing rule (63 FR 53609), ``While this
taxon remains vulnerable to the OHV use occurring over most of its dune
habitat, the Service believes that the dispersed nature of its colonies
and the wilderness designation reduce the potential for immediate
extinction.''
BLM temporarily closed areas of the Algodones Dunes to off-highway
and other vehicular traffic effective November 3, 2000. Notwithstanding
the 2005 Record of Decision, 2003 RAMP, and Final Environmental Impact
Statement for the ISDRA where BLM (2003a) proposed to reopen those
temporary closures to OHV activity, the U.S. District Court for the
Northern District of California ordered, among other things, that BLM
``maintain the vehicle closures as identified in the `Temporary Closure
of Approximately 49,300 Acres to Motorized Vehicle Use of Five Selected
Areas in the ISDRA'.'' If the court order is lifted and these areas are
reopened, the threat to A. magdalenae var. peirsonii would increase
above current levels. Such action would open 29 percent of the ISDRA to
OHV use, leaving the 27,700-ac (11,200-ha) Wilderness as the only
closed area. Removing the closures and/or increasing the number of
camping pads in the Gecko and Ogilby Management Areas is likely to
reduce A. magdalenae var. peirsonii in those management areas
significantly (Bartel in litt. 2007, p. 2). However, we expect that the
species will continue to persist in fewer numbers in Gecko and Ogilby,
even if OHV use increases.
In addition, as noted above in Factor A, there is considerable
uncertainty with respect to future management of the Algodones Dunes.
In light of the uncertain status of the 2003 RAMP, we believe that
adequate regulatory mechanisms are not yet in place to support removing
the protections of the Act.
E. Other Natural or Manmade Factors Affecting Its Continued Existence
Trespass. Although the range-wide impact is difficult to assess, we
have received an increase in reports of purposeful or unintentional
trespass into Astragalus magdalenae var. peirsonii habitat that is
closed to OHV use. Porter (2002b, pp. 2-3) described tracks and
incursions of OHVs into areas closed to OHV traffic and an instance
where all of the aerial stems of a plant had been cut off. These closed
areas are outside of the Wilderness. Activity of this nature has been
noted on maps and by ground personnel (Willoughby 2000, Map 24; Porter
2002b, p. 2).
Low reproduction. Astragalus magdalenae var. peirsonii may also be
threatened by low numbers of reproducing individuals, a circumstance
that occurs from time to time. As noted earlier, not all plants flower
each year. Movements and fluctuations of populations have not been
recorded for a long enough period to assess the significance of low
reproduction to the survival of the taxon. The BLM (Willoughby 2001, p.
22) reported a total of only 86 plants throughout their transect areas
in the 2000 survey. Phillips et al. (2001, p. 10) found only 5 plants
more than a year old out of the
[[Page 41021]]
72,000 counted in their survey covering approximately 35,000 ac (14,000
ha) open to OHV use in 2001. Having so few older individuals may be a
concern given that the older, larger plants contribute more to the seed
bank than younger, flowering juveniles (Romspert and Burk 1979, p. 28;
Phillips and Kennedy 2002, p. 27). Random events, like periodic
drought, may have a significant detrimental effect on the species when
so few individuals are present or when the habitat requirements are so
narrow that random environmental conditions can result in the demise of
an entire cohort. In 2003, the entire cohort of seedlings was lost due
to delayed germination and high temperatures (Phillips and Kennedy
2003, p. 15; Porter 2003b, p. 1). The ecological impact of any cyclic
depletion and restoration of the seed bank is unknown.
Fragmentation and isolation. As discussed above, less than 9
percent of A. magdalenae var. peirsonii plants were observed in the
Wilderness in 2005. Implementation of the 2003 RAMP, as currently
written, would fragment the entire range of the A. magdalenae var.
peirsonii population into management islands of plants separated by
large OHV-impact areas (see Willoughby 2006, Map 6). Effects to A.
magdalenae var. peirsonii from fragmentation would be difficult to
measure but may include lower seed production due to reduced visitation
by pollinators (Jennersten 1988, pp. 361-363; Steffan-Dewenter and
Tscharntke 1999, pp. 434-436; Baron and Bros 2005, pp. 48-50) and
increased local predation pressure in instances where populations are
reduced to isolated individuals (Girdler and Radtke 2006, pp. 220-222).
If the Wilderness were isolated and the total population diminished as
estimated, in light of proposed management actions, justification to
delist A. magdalenae var. peirsonii would be difficult. Astragalus
magdalenae var. peirsonii has evidently persisted at low abundance in
areas of moderate to high OHV use over the short term. However, because
protection is ensured for only 9 percent of the population, Astragalus
magdalenae var. peirsonii is at increased risk of long-term population
decreases due to events such as long-term drought, climate change, or
focused predation.
Significant Portion of the Range Analysis
On March 16, 2007, a formal opinion was issued by the Solicitor of
the Department of the Interior, ``The Meaning of `In Danger of
Extinction Throughout All or a Significant Portion of Its Range' ''
(U.S. DOI 2007). We have summarized our interpretation of that opinion
and the underlying statutory language below. A portion of a species'
range is significant if it is part of the current range of the species
and it contributes substantially to the representation, resiliency, or
redundancy of the species. The contribution must be at a level such
that its loss would result in a decrease in the ability to conserve the
species. In other words, in considering significance, the Service
should ask whether the loss of this portion likely would eventually
move the species toward extinction, but not necessarily to the point
where the species should be listed as threatened.
The first step in determining whether a species is threatened or
endangered in a significant portion of its range is to identify any
portions of the range of the species that warrant further
consideration. The range of a species can theoretically be divided into
portions in an infinite number of ways. However, there is no purpose to
analyzing portions of the range that are not reasonably likely to be
significant and threatened or endangered. To identify only those
portions that warrant further consideration, we determine whether there
is substantial information indicating that (i) the portions may be
significant and (ii) the species may be in danger of extinction there
or likely to become so within the foreseeable future. In practice, a
key part of this analysis is whether the threats are geographically
concentrated in some way. If the threats to the species are essentially
uniform throughout its range, no portion is likely to warrant further
consideration. Moreover, if any concentration of threats applies only
to portions of the range that are unimportant to the conservation of
the species, such portions will not warrant further consideration.
If we identify any portions that warrant further consideration, we
then determine whether in fact the species is threatened or endangered
in any significant portion of its range. Depending on the biology of
the species, its range, and the threats it faces, it may be more
efficient for the Service to address the significance question first,
or the status question first. Thus, if the Service determines that a
portion of the range is not significant, the Service need not determine
whether the species is threatened or endangered there; if the Service
determines that the species is not threatened or endangered in a
portion of its range, the Service need not determine if that portion is
significant.
Finding
As required by the Act, we considered the five potential threat
factors to assess whether Astragalus magdalenae var. peirsonii is
threatened or endangered throughout all or a significant portion of its
range. When considering the listing status of the species, the first
step in the analysis is to determine whether the species is threatened
or endangered throughout all of its range. The status review for A.
magdalenae var. peirsonii contained in this document is for the entire
range of this species as listed under the Act.
We have carefully assessed the best scientific and commercial
information regarding the biology of this species and its threats. We
reviewed the updated petition and associated documents, information
available in our files, and other published and unpublished information
submitted to us during the public comment period following our 90-day
petition finding. We also reviewed new data and information on the life
history and ecology of Astragalus magdalenae var. peirsonii.
For many years controversy has focused on the abundance of
Astragalus magdalenae var. peirsonii in any given year and the
implications of abundance figures for the long-term persistence of the
species. For a species that fluctuates widely in numbers from year to
year, an assessment of abundance may not be the most meaningful measure
of the likelihood of persistence. Characterizing the population trend,
resilience, and long-term viability of A. magdalenae var. peirsonii
would be more relevant but has not been done in a rigorous and
meaningful manner to date. In addition, we agree with the updated
petition (ASA 2005) that understanding the soil seed bank is important
to understanding the long-term viability of A. magdalenae var.
peirsonii. However, we do not agree that the nature, extent, and
dynamics of the seed bank for A. magdalenae var. peirsonii have been
characterized to the point that we fully understand the seed bank's
contribution to the long-term persistence of A. magdalenae var.
peirsonii. In addition, we do not agree that the available data provide
evidence that A. magdalenae var. peirsonii will continue to persist
because of the extent and nature of its seed bank. In short, we have an
incomplete understanding of the relationship of abundance data and seed
bank data to the long-term persistence of A. magdalenae var. peirsonii.
Therefore, we cannot conclude that high numbers of above-ground plants
and the purported large numbers of seeds in the seed bank
[[Page 41022]]
ensure the long-term persistence of the species.
We continue to consider OHV activity the primary threat to
Astragalus magdalenae var. peirsonii. Documentation available attests
to historical and ongoing OHV impacts to the species (WESTEC 1977, pp.
1-135; ECOS 1990, pp. 1-85; Willoughby 2000, pp. 1-37, 2001, pp. 1-31,
2004, pp. 1-20, 2005, pp. 1-; Phillips et al. 2001, pp. 1-13; Phillips
and Kennedy 2003, pp. 1-21; Groom et al. 2007, pp. 119-134; USFWS
2006b, pp. 1-9, and 2007, pp. 1-36). Areas within the dunes subject to
intensive OHV use (e.g., staging areas) have a lower abundance of A.
magdalenae var. peirsonii. Longer-term monitoring indicates that plants
exposed to OHV activity have a reduced likelihood of survival (e.g.,
Groom et al. 2007, pp. 128-130). Available information suggests that
within the foreseeable future OHV use will continue to increase and
pose a threat to the survival of A. magdalenae var. peirsonii, and we
can reliably predict that the impacts of continued and increasing
levels of OHV use anticipated to occur, particularly if A. magdalenae
var. peirsonii is no longer listed, would likely result in a downward
trend in the population until A. magdalenae var. peirsonii is in danger
of extinction. Secondary threats to A. magdalenae var. peirsonii
include rodent and insect herbivory, seed predation, and effects of
fragmentation and environmental stochasticity/catastrophes, all which
may be exacerbated by the low reproduction of A. magdalenae var.
peirsonii.
While the North Algodones Dunes Wilderness will continue to be
closed to OHV use, this area alone is not sufficient to ensure the
long-term survival of Astragalus magdalenae var. peirsonii because it
provides only a small percentage of the entire habitat for this species
within the Algodones Dunes and the area provides less available habitat
for this plant relative to the areas south of State Route 78 that have
in the past or may in the future be open to OHV use. Based on the 2005
population estimates derived by the BLM, less than 9 percent of the A.
magdalenae var. peirsonii population in the United States occurs within
the Wilderness. The distribution of A. magdalenae var. peirsonii from
pre-2003 surveys indicates a higher relative abundance of plants in the
central dunes south of State Route 78 and more recent surveys confirm
this observation. Thus, the Wilderness alone is not sufficient to
sustain this species because it does not provide sufficient habitat and
habitat quality to ensure the long-term survival of this species, and
the long-term viability of the species within the Wilderness is
dependent upon the remainder of the range remaining viable. Thus,
although direct impacts from OHV use are minimal within the Wilderness,
the overall impacts to A. magdalenae var. peirsonii within the
Wilderness that may result from the combined threats discussed above
(including indirect effects of OHV use) are essentially equal to those
present throughout the rest of the species' range.
Applying the process described above under ``Significant Portion of
the Range Analysis'' for determining whether a species is threatened or
endangered in a significant portion of its range, we next address
whether any portions of the range of Astragalus magdalenae var.
peirsonii warrant further consideration. As explained above, we have
determined that A. magdalenae var. peirsonii remains threatened
throughout all of its range due to the direct mortality, reduced
survival, and/or reduced reproductive success that we predict would
result from the effects of the identified threats analyzed in the five-
factor analysis. We do not have any data suggesting that the identified
threats to the species are concentrated in any portion of the range
such that A. magdalenae var. peirsonii may be in danger of extinction
in that portion. Therefore, we find that there are no portions of the
range that warrant further consideration.
After a thorough review and consideration of all information
available, we find that delisting Astragalus magdalenae var. peirsonii
is not warranted at this time because the plant continues to be at risk
due to the threats described above. We find that A. magdalenae var.
peirsonii remains likely to become an endangered species within the
foreseeable future throughout all of its range and should remain
classified as a threatened species. In making this determination, we
have followed the procedures set forth in section 4(a)(1) of the Act
and regulations implementing the listing provisions of the Act (50 CFR
part 424).
We will continue to monitor the status of the species, and to
accept additional information and comments from all concerned
governmental agencies, the scientific community, industry, or any other
interested party concerning this finding.
References Cited
A complete list of all references cited in this document is
available upon request from the Carlsbad Fish and Wildlife Office (see
ADDRESSES).
Author
The primary author of this document is Lloyd B. McKinney of the
Carlsbad Fish and Wildlife Office (see ADDRESSES).
Authority: The authority for this action is the Endangered
Species Act of 1973, as amended (16 U.S.C. 1531 et seq.).
Dated: July 2, 2008.
Kenneth Stansell,
Acting Director, Fish and Wildlife Service.
[FR Doc. E8-16041 Filed 7-16-08; 8:45 am]
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