Endangered and Threatened Wildlife and Plants; Withdrawal of Proposed Rule to List the Plants Astragalus lentiginosus var. micans (shining milk-vetch) and Astragalus lentiginosus var. sesquimetralis (Sodaville milk-vetch) as Threatened

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

RIN 1018-AB75

Endangered and Threatened Wildlife and Plants; Withdrawal of

Proposed Rule to List the Plants Astragalus lentiginosus var. micans

(shining milk-vetch) and Astragalus lentiginosus var. sesquimetralis

(Sodaville milk-vetch) as Threatened

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule; withdrawal.

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SUMMARY: The U.S. Fish and Wildlife Service (Service) withdraws the

proposed rule to list Astragalus lentiginosus var. micans (shining

milk-vetch) and Astragalus lentiginosus var. sesquimetralis (Sodaville

milk-vetch) as threatened, pursuant to the Endangered Species Act of

1973, as amended (Act). These plants are two of seven desert Astragalus

taxa from California and Nevada that were included in a proposed rule

published on May 8, 1992 (57 FR 19844). Since the proposed rule was

published, management of the lands which support one population of A.

lentiginosus var. sesquimetralis and both locations where A.

lentiginosus var. micans occurs, have been transferred to wilderness

under management of the National Park Service at Death Valley National

Park. Based on evaluation of this information and public comments, and

reevaluation of existing data, the Service has determined that evidence

of sufficient threat warranting the listing of Astragalus lentiginosus

var. micans and Astragalus lentiginosus var. sesquimetralis is not

present at this time. The Service will continue to monitor the status

of these species and may reevaluate the need for their listing at any

time in the future on the basis of new information and/or actual or

potential habitat alteration detrimental to the plants' continued

existence.

ADDRESSES: The complete files for these actions are available for

inspection, by appointment, during normal business hours. For

Astragalus lentiginosus var. sesquimetralis contact the Nevada State

Office, U.S. Fish and Wildlife Service, 1340 Financial Blvd., Suite

234, Reno, NV 89502. For A. lentiginosus var. micans contact the

Ventura Fish and Wildlife Office, U.S. Fish and Wildlife Service, 2493

Portola Road, Suite B, Ventura, CA 93003.

FOR FURTHER INFORMATION CONTACT: Nevada State Office Supervisor, at the

above address; telephone 702-861-6300 (for Astragalus lentiginosus var.

sesquimetralis) or Ventura Field Supervisor, above address; telephone

805-644-1766 (for Astragalus lentiginosus var. micans).

SUPPLEMENTARY INFORMATION:

Background

On May 8, 1992, the Service published a proposal in the Federal

Register (57 FR 19844) to list as endangered or threatened seven desert

plant taxa in the genus Astragalus which occur in California and

Nevada. The proposed listing was followed by a 60-day comment period

that closed on July 7, 1992. A final determination on the proposal was

delayed by other listing priorities, a limited budget, and the Federal

moratorium on final listing actions. After the proposed rule was

published, changes in the management of desert lands occurred and new

conservation activities were initiated in some of the areas where these

taxa occur. Due to these changes and the amount of time that had

elapsed since the original publication, the Service reopened a 45-day

comment period for the proposed listing on September 3, 1996 (61 FR

46430).

The Service has considered all available information and withdraws

its proposal to list these two taxa. The proposal for Astragalus

lentiginosus var. micans is withdrawn because the Service lacks

sufficient evidence to indicate that vehicle trespass, visitor use, and

the presence of Russian thistle (Salsola sp.), an invasive, nonnative

plant, currently subject this taxon to significant threat. The proposal

for A. lentiginosus var. sesquimetralis is withdrawn because the

Service lacks sufficient evidence to indicate that livestock and

vehicle trespass, or development of its habitat are currently

threatening this taxon.

Astragalus lentiginosus var. micans (shining milk-vetch) was

described by Rupert Barneby (1956) based on two specimens (co-types)

collected on the lower slopes of sand dunes at the southeast end of

Eureka Valley, Inyo County, California in 1955. A flowering collection

was made by Philip Munz and John Roos in April 1955 and a fruiting

specimen was collected by Roos in May 1955. The plant is an erect

white-silky perennial with a hardened base. The leaves range from 4.5

to 9.5 centimeters (cm) (1.8 to 3.7 inches (in.)) in length and consist

of 11 to 17 leaflets. The flowers are cream to pale yellow with

lavender or indigo distally, and are arranged in loose, 20-to 35-

flowered racemes. The pods are stiffly papery, inflated, and often

angled upward to a distinct beak (Barneby 1964).

Astragalus lentiginosus var. micans is restricted to sands of the

lower slopes and base of dunes at two sites located about 6 kilometers

(km) (4 miles (mi)) apart in the Eureka Valley. These two sites, the

Eureka Dunes and the Saline Spur Dunes, represent the entire known

historic and the current range of this taxon (Barneby 1956; Spellenberg

1993; Bruce Pavlik, Mills College, in litt. 1983 and 1996). Potential

populations from Big Dune, Nevada, erroneously noted in the proposed

rule as possibly being A. lentiginosus var. micans (57 FR 19845), had,

in fact, already been identified from past collections as A.

lentiginosus var. variabilis (Pavlik, in litt. 1980, 1996; R. Barneby,

New York Botanical Garden, in litt. 1981).

Of the two sites in the Eureka Valley where this plant occurs, the

Eureka Dunes, approximately 5 km (3 mi) long and up to 2.4 km (1.5 mi)

in width, appears to support the most substantial population of

Astragalus lentiginosus var. micans. As mapped (Bagley 1986), the

distribution of this taxon on the Saline Spur Dunes, to the east, is

more restricted. In the 1960s and 1970s, increasing off-highway vehicle

(OHV) use on the Eureka Dunes destroyed vegetation over the northern

end of the lower dunes and flats, an area that supports A. lentiginosus

var. micans (Bureau of Land Management (BLM) 1976, Service 1982). Two

other taxa endemic to dunes of the Eureka Valley, Oenothera californica

ssp. eurekensis (Eureka Valley evening primrose, formerly O. avita ssp.

eurekensis) and Swallenia alexandre (Eureka Valley dune grass), co-

occur with A. lentiginosus var. micans and were federally listed as

endangered in 1978 (43 FR 17910) as a result of this activity. The BLM

closed the dunes to OHV use in 1976, although active enforcement of the

closure wasn't effective until 1980. Since that time, botanists have

noted that A. lentiginosus var. micans appears to be recolonizing the

formerly disturbed areas (Pavlik 1979; Service 1982; Mark Skinner,

California Native Plant Society (CNPS), in litt. 1995), although

censuses before and after the closure are not available. The dunes were

managed by the BLM until 1994, when passage of the California Desert

Protection Act (CDPA) of 1994 transferred the area to the National Park

[[Page 53632]]

Service (NPS) at Death Valley National Park. Both sites are now

included in wilderness areas within the park.

The primary threats to Astragalus lentiginosus var. micans

identified in the proposed rule were illegal off-road vehicle activity

at the Eureka Dunes and competition with Russian thistle. These issues

are discussed within this document under factors A, D, and E of the

``Summary of Factors Affecting the Species'' section of this rule.

Astragalus lentiginosus var. sesquimetralis (Sodaville milk-vetch)

was first collected by W.H. Shockley in 1882 near Sodaville, Mineral

County, Nevada, and described by Per Axel Rydberg as Cystium

sesquimetrale (Rydberg 1929). The segregate genus Cystium, however, is

not recognized by other botanists, and in 1945, Barneby reclassified

the plant as Astragalus lentiginosus var. sesquimetralis. The plant is

a prostrate perennial with straw-colored stems up to 80 cm (31 in.)

long and covered with silky hairs. The leaflets are 6 to 18 millimeters

(mm) (0.2 to 0.7 in.) long. The light purple flowers have white silky

calyces 7 to 8 mm (0.3 in.) long, arranged on 6-to 12-flowered racemes.

The pod is moderately inflated, 1.6 to 2.6 cm (0.6 to 1.0 in.) long,

with an upwardly curved beak.

Astragalus lentiginosus var. sesquimetralis occurs on powdery clay

saline soils adjacent to springs. The taxon is known globally from

three sites that are arrayed along a north-south line through a low

topographic corridor of the western Great Basin, known as the Lahontan

Trough. Those sites are Big Sand Spring, Death Valley National Park,

Inyo County, California; Cold Springs, Nye County, Nevada; and

Sodaville, Mineral County, Nevada (Morefield 1993).

The Big Sand Spring site of Astragalus lentiginosus var.

sesquimetralis, like the Eureka Dunes and Saline Sand Spur localities

of A. lentiginosus var. micans, was under BLM management until 1994.

Passage of the CDPA transferred the site to NPS management by inclusion

within a wilderness area of Death Valley National Park. The site was

maintained within a cattle grazing allotment and a wild burro Herd

Management Area by BLM, and it currently retains those designations

under NPS management. Although a fenced exclosure was constructed

around the Big Sand Spring site and adjacent spring habitat in 1986 as

an effort to protect A. lentiginosus var. sesquimetralis, cattle and

burros continued to access the site on occasion by breaking through the

fence or by climbing over the fence from the dredge spoils just outside

of the exclosure (California Department of Fish and Game (CDFG) in

litt. 1988). In the fall of 1996, NPS tore down and replaced sections

of the old fence (NPS, in litt. 1996). Population surveys at this

location has not been completed annually or systematically and

population size probably varies according to precipitation, as well as

other environmental factors. Several hundred to a thousand individuals

have been recorded at this site in the last decade (Constance

Rutherford, BLM, in litt. 1989, James Morefield, Nevada Natural

Heritage Program (NNHP), in litt. 1991).

The privately owned and maintained sites of Astragalus lentiginosus

var. sesquimetralis at Cold Springs (10 hectares (ha) (25 acres (ac))

in Nye County) and Sodaville (10 ha (25 ac) in Mineral County), Nevada

are adjacent to BLM grazing allotments. Although the sites are subject

to cattle and burro trespass, the Service has no evidence of grazing or

trampling damage on either site from cattle and burros (Morefield

1993). Because both sites are adjacent to highways, potential damage to

the plants and their habitat by vehicular trespass, commercial

development, and/or associated roadside activities has been suggested

(Morefield 1993, 57 FR 19844). To date, however, no permit requests for

development of either property site or the waters thereon have been

filed with state or county permitting authorities, and no evidence of

vehicular trespass has been recorded since 1978 (Morefield 1993). The

Sodaville property is also the site of a refugia population of Railroad

Valley Springfish (Chrenichthys nevadae), a federally threatened

species that occupies adjacent springs (Mike Sevon, Nevada Division of

Wildlife (NDOW), in litt. 1996). At the time of the last census of

these sites in 1992, about 600 to 750 plants were known to exist at the

Sodaville site (Morefield 1993) and about 500 plants at the Cold

Springs site (Morefield 1993). No population trend data are available

for these populations and their current population status is unknown.

Threats to A. lentiginosus var. sesquimetralis identified in the

proposed rule are discussed further under factors A and E of the

``Summary of Factors Affecting the Species'' section of this notice.

Public Comments on the Proposed Rule

During the two comment periods in 1992 and 1996, all interested

parties were requested to submit factual reports or information to be

considered in making a final listing determination. Appropriate Federal

and State agencies, the Mexican government, local governments,

scientific organizations, and other interested parties were notified

and their comments solicited regarding the 1992 proposed rule and on

any changes in management or threats that may have occurred since that

time. Legal notices inviting general public comment were published in

the appropriate California and Nevada local newspapers.

Comments specifically relevant to Astragalus lentiginosus var.

micans or A. lentiginosus var. sesquimetralis are incorporated into

this withdrawal notice where appropriate. The Service has not prepared

a discussion or response to several additional comments that were

received in support of withdrawal of A. lentiginosus var.

sesquimetralis because these comments did not provide any additional

relevant information concerning the species' biology, population size,

numbers or distribution; threats or lack thereof; or conservation

agreements or other protection instruments and their possible impacts

to the species.

Of the parties specifically addressing A. lentiginosus var. micans,

two expressed concern that NPS does not have adequate funds or staff to

protect the Eureka Dunes from vehicle trespass, three expressed concern

about the occurrence of Russian thistle at the base of the Dunes, one

suggested that Indian rice grass (Oryzopsis hymenoides) might threaten

A. lentiginosus var. micans in the future, and one requested that the

final determination on this listing action be delayed until completion

of the Northern and Eastern Mojave Ecosystem Management Plan (NEMO).

The issues of vehicle trespass and the occurrence of Russian thistle

are discussed under factors A, D, and E of the ``Summary of Factors

Affecting the Species'' section of this notice. In regard to Indian

rice grass, the Service is not aware of any information to suggest that

this native species is currently a threat to this taxon. In response to

the suggestion to delay the final determination of this listing action,

the Service cannot delay action on a proposed rule, except in

circumstances where there is substantial disagreement among

knowledgeable scientists regarding the sufficiency or accuracy of data

relevant to the determination (50 CFR 424.17).

Several comments received during the 1992 comment period questioned

the varietal distinctiveness of Astragalus lentiginosus var. micans. In

preparing this withdrawal notice, the Service has determined that the

most recent taxonomic treatment of the genus (Spellenburg 1993) and

information received from an expert on the species during the 1996

comment period

[[Page 53633]]

(Pavlik, in litt. 1996) treat the taxon as distinct at the varietal

level.

Issue 1: Five commenters raised issues specifically relating to

Astragalus lentiginosus var. sesquimetralis. The comment concerning a

delayed determination of the proposed listing of this taxon was

addressed in the above paragraph regarding A. lentiginosus var. micans.

This commenter also expressed concern that competition from wild

licorice (Glycyrrhiza lepidota) was an additional potential threat to

the Death Valley population.

Service Response: The Service is not aware of any information

suggesting that wild licorice poses a threat to A. lentiginosus var.

sesquimetralis.

Issue 2: One comment expressed concern about livestock and burro

trespass and the feasibility of burro-proof fencing at the Death Valley

site.

Service Response: Livestock and burro trespass is addressed in

factors A, B, and C of the ``Summary of Factors Affecting the Species''

section of this notice.

Issue 3: One comment challenged the appropriateness of listing

plant varieties under the Act.

Service Response: Section 3(16) of the Act states that ``(t)he term

``species'' includes any subspecies of fish or wildlife or plants * * *

which interbreeds when mature.'' The Service discussed in a Federal

Register notice published on April 16, 1978 (43 FR 17912) the common

use of the terms ``species'' and ``varieties'' by botanists and

concluded that plants named as ``varieties'' are essentially subspecies

and, therefore, ``species'' as defined in the Act.

Issue 4: One commenter stated that Astragalus lentiginosus var.

sesquimetralis is a poisonous, narcotic plant that, as such, should not

be protected by the Federal government. This commenter also expressed

concern over Federal protection of a species that the State of Nevada

referred to as ``locoweed'' and had gone so far as to ban its commerce

under a Nevada Revised Statute (NRS).

Service Response: In response to the latter concern, no Astragalus

fit the characteristics of noxious species as classified by the State

of Nevada, and therefore, none are listed as noxious weeds under the

NRS (NRS 555) (John O'Brien, Nevada Division of Agriculture, in litt.

1996). Because many plants are commonly called ``locoweeds,'' plant

identities are often confused when common names are used in literature,

and the commenter may have confused Astragalus with other locoweeds.

Astragalus lentiginosus var. sesquimetralis does contain compounds that

may cause toxic and/or narcotic reactions when eaten by animals, as do

most Astragalus species and many other species of plants, including

some that are common in human diets (e.g., the potato Solanum

tuberosum) (Kingsbury 1964). That characteristic alone does not affect

a listing decision under the Act.

Issue 5: A ``joking reference'' to vandalizing A. lentiginosus var.

sesquimetralis on the private property where it exists was made at a

local public meeting in Nye County, NV (Pahrump Valley Times, October

4, 1996).

Service Response: Because this comment was not made by the private

property owner, nor was there any evidence that this threat was

supported by the property owner, vandalism is not currently considered

by the Service to be a threat to A. lentiginosus var. sesquimetralis,

particularly since this species is being withdrawn from consideration

for listing.

Summary of Factors Affecting the Species

The Act and implementing regulations found a 50 CFR 424.17(3)

provide the basis for determining a species to be endangered or

threatened and for withdrawing a proposed rule when it has not been

found to be supported by available information. The five factors

described in section 4(a)(1) of the Act, as they apply to the

withdrawal of the proposed listing of Astragalus lentiginosus Dougl.

var. micans Barneby (shining milk-vetch) and Astragalus lentiginosus

Dougl. var. sesquimetralis (Rydb.) Barneby (Sodaville milk-vetch), are

as follows:

A. The Present or Threatened Destruction, Modification, or Curtailment

of its Habitat or Range.

Off highway vehicle use has been the primary threat to Astragalus

lentiginosus var. micans. Beginning in the 1960s, the Eureka Dunes

became a popular location to ride OHVs, including dune buggies (Service

1982). On Easter weekend in 1976, for example, almost 50 vehicles were

reported at the Eureka Dunes (BLM 1976). The height of vehicle damage

to the endemic plants of the Eureka Dunes probably occurred by the mid

to late 1970s (Service 1982). Two other plant taxa endemic to the

Eureka Valley were listed as endangered in 1978 (43 FR 17910) as a

result of OHV activity.

Due, in part, to public concern over the declining condition of the

dune's endemic flora, BLM officially closed the Eureka Dunes to OHV use

in 1976. However, it was not until 1980 that BLM rangers and other

personnel effectively enforced the closure (Service 1982). In the 1980s

and early 1990s, BLM continued to maintain the closure and installed

pipe barriers, wooden barriers, and signs around the northwest and

central parking areas to block vehicle access to the dunes and to

direct visitor use. During the past decade, the patrols and barriers

have effectively prevented most vehicle trespass outside the confines

of the parking area, although occasional trespass has still occurred

(BLM, in litt. 1992; Glenn Harris, BLM, pers. comm. 1996). During

transfer of the management of the Eureka Valley to NPS, the wooden

barriers in the northwest parking area were stolen (G. Harris, pers.

comm. 1996) and a few individual plants of Astragalus lentiginosus var.

micans recolonizing the parking area were run over by vehicles (Renee

Beymer, NPS, in litt. 1996; Diane Steeck, Service, pers. obs. 1996). In

the fall of 1996, NPS installed temporary t-post barriers in the

parking area, which they replaced with NPS wilderness markers a few

months later. The Park is in the process of placing more permanent

barriers and reducing the size of the parking area to allow the milk-

vetch to recolonize an area at the dune base previously denuded by

vehicles. The NPS reports that ranger patrols of the area occur at

about the same level as before the Eureka Valley was transferred to its

management (NPS, in litt. 1996).

The Service concludes that the BLM's earlier efforts to reduce

vehicle trespass at the north end of the Eureka Dunes, combined with

the current reduction in the size of the northwest parking area to

allow Astragalus lentiginosus var. micans to continue recolonizing the

sandy flats, and the continuation of enforcement patrols by NPS have

reduced vehicle trespass into the population to the extent that vehicle

trespass does not currently constitute a significant threat to the

survival of this taxon. The Service is working with NPS to identify and

implement additional conservation activities to manage visitor numbers

and use patterns into the future.

The second location where Astragalus lentiginosus var. micans

occurs, the Saline Spur Dunes, is also located within wilderness under

NPS management. This location is fairly isolated, lacks road access,

and receives little human visitation, consequently the Service believes

threats to this location are minimal.

The alkaline spring-associated habitat of Astragalus lentiginosus

var. sesquimetralis is vulnerable to surface developments, water

diversions, vehicular traffic, and trampling by

[[Page 53634]]

domestic and wild herbivores. The Cold Spring and Sodaville populations

of this taxon occur entirely on private land. Any development

activities that result in surface disturbances or decreased spring

flows could threaten these populations. While the owner of the

Sodaville property has expressed future intent to develop a portion of

the 64 ha (160 ac) surrounding the springs, his intention is not to

disturb or threaten A. lentiginosus var. sesquimetralis or its habitat

(Durk Pearson, HRH Resources, pers. comm. 1996). To date, neither

property owner has filed for any of the State or county permits

necessary for development of property or the waters thereon. The

Service has no evidence of activity that would represent a substantial

threat to A. lentiginosus var. sesquimetralis on private property at

this time.

The Big Sand Spring site recently has passed from BLM authority to

that of NPS by inclusion in Death Valley National Park through the CDPA

of 1994. While under BLM authority, this site was managed as both an

Area of Critical Environmental Concern and a Wild Horse and Burro Herd

Management Area. As such, it was vulnerable to trampling by feral

burros and livestock due to breaks in exclosure fencing and other means

of access. As part of NPS's current management activities to mitigate

or eliminate potential threats to this taxon (NPS, in litt. 1996), new

fencing has been constructed around Big Sand Spring. The NPS has

identified and implemented further conservation activities, such as

monitoring and increased patrol efforts.

The Service concludes that development does not pose a threat to

this taxon, and impacts from livestock have currently been reduced to

the extent that they no longer pose a threat to this taxon.

B. Over Utilization for Commercial, Recreational, Scientific, or

Educational Purposes

There are no known commercial values or purposes for these species.

C. Disease or Predation

Disease is not known to be a factor for these taxa. As discussed

under Factor A of the ``Summary of Factors Affecting the Species''

section of this notice, Astragalus lentiginosus var. sesquimetralis may

be subject to grazing by livestock and burros in the Big Sand Spring

location, but trampling is more likely, due to toxicity of the plants

(BLM, in litt. 1992). New fencing at the site has been constructed to

prevent access by livestock and burros (C. Mullen, pers. obs. 1997).

D. The Inadequacy of Existing Regulatory Mechanisms

The Endangered Species Act should provide protection to Astragalus

lentiginosus var. micans at the Eureka Dunes and Saline Spur Dunes by

virtue of the co-existence of this taxon with two other listed plant

taxa, Oenothera californica ssp. eurekensis and Swallenia alexandre.

Although they prefer somewhat different sand depths and stability, the

majority of the mapped distribution of A. lentiginosus var. micans

coincides with that of the Oenothera at the Eureka Dunes and with both

taxa over much of the Saline Spur Dunes (BLM 1976, Bagley 1986). In

1982 the Service funded preparation of a Recovery Plan for the Eureka

Valley Dunes. The two major tasks identified in the plan involved, (1)

removing human threats to the Eureka Dunes and auxiliary dunes where

these species occur, and (2) determining population and habitat

conditions needed to ensure their survival, and then managing for those

conditions. These tasks have been partially completed and have

benefitted A. lentiginosus var. micans as well as the two listed taxa

(Harris 1994 as cited in Noell 1994). The co-occurrence of A.

lentiginosus var. micans with these listed plants should offer it

substantial protection from visitor use and vehicle trespass, providing

NPS enforces compliance and manages visitor use to adequately protect,

and promote the recovery of, the listed taxa.

Long-term management actions to mitigate or eliminate potential

threats to areas in the eastern Mojave Desert, including Park sites

that support Astragalus lentiginosus var. micans and A. lentiginosus

var. sesquimetralis are currently being formulated by NPS for inclusion

in the NEMO Plan (NPS, in litt. 1996), a joint effort of NPS, BLM, and

the Service. This plan is still being formulated, however, and does not

currently provide any additional protection to these species. NPS is

developing a monitoring program for both A. lentiginosus var. micans

and A. lentiginosus var. sesquimetralis at the sites within Death

Valley National Park where they occur.

Astragalus lentiginosus var. sesquimetralis is on the State of

Nevada's list of critically endangered species in accordance with

Nevada Revised Statute 527.270. Under the terms of State law, this

statute provides that ``no member of its kind may be removed or

destroyed at any time by any means except under special permit issued

by the State Forester Firewarden'' (NRS 527.270). Private property

development affecting the plant directly, or indirectly through habitat

modification, would require a permit from the Nevada Division of

Forestry prior to removal or destruction. The Sodaville site is also

the location of a population of Railroad Valley Springfish, a federally

listed threatened fish that is protected under the Act. Existing

regulatory mechanisms, given the current status of the species, are

adequate.

E. Other Natural or Manmade Factors Affecting Their Continued Existence

A potential threat to Astragalus lentiginosus var. micans at the

Eureka Dunes is the occurrence and spread of Russian thistle. Although

Russian thistle was documented on the dunes in the 1970s and 1980s, it

appears to have increased from the mid to late 1980s around the base of

the main Eureka Dune, particularly along the dune's east side (Bagley,

pers. comm. 1996). While there is substantial concern about the

occurrence of Russian thistle around the dunes (Mary DeDecker, CNPS, in

litt. 1996; Mark Bagley, CNPS, pers. comm. 1996, Mary Ann Henry, CNPS,

in litt. 1996), its effect on A. lentiginosus var. micans is unknown.

Pavlik (in litt. 1996) did not find that cover by Russian thistle

affected reproduction or survivorship of A. lentiginosus var. micans

when he conducted research on the dunes, although cover of thistle may

have increased since that time (Bagley, pers. comm. 1996). However, the

active growing season of A. lentiginosus var. micans and Russian

thistle do not coincide. Astragalus lentiginosus var. micans exhibits

most of its growth in the early spring, with flowering from March to

June (Pavlik 1979), while the period of greatest growth for Russian

thistle is late spring and summer, with flowering from August to

October (The Nature Conservancy 1986; BLM, in litt. 1992; B. Pavlik, in

litt. 1996). This reduces the likelihood of direct competition for

water between these taxa (BLM, in litt. 1992; B. Pavlik, in litt.

1996). Although Russian thistle may not exhibit a direct, measurable,

effect on A. lentiginosus var. micans, it may affect it indirectly,

through its influence on other biota or on abiotic factors of the dune

community (B. Pavlik, in litt. 1996). Nonetheless, based on the

evidence available at this time, the Service concludes that Russian

thistle does not substantially affect the long-term existence of this

taxon in the Eureka Valley.

The possibility of destruction of plants, especially seedlings, of

Astragalus lentiginosus var. micans

[[Page 53635]]

from trampling by dune visitors is also a concern (R. Beymer, pers.

comm. 1996; B. Pavlik, in litt. 1996). The road leading out of the

north end of Death Valley National Park, past the Eureka Dunes access

road, has been improved in the last 2 years, and additional portions of

it have been paved (R. Beymer, pers. comm. 1996). Although NPS has

neither publicized nor planned any improvements in facilities at the

Eureka Dunes, the area is likely to attract more visitors due to its

recent inclusion within a National Park. The Service acknowledges the

potential for trampling by visitors to affect A. lentiginosus var.

micans, but concludes that evidence is insufficient to conclude that

the Park cannot adequately manage visitor use to effectively protect

this taxon and promote the recovery of the co-occurring listed taxa on

the dunes.

The naturally limited global distribution and abundance of

Astragalus lentiginosus var. micans and A. lentiginosus var.

sesquimetralis increase their vulnerability to extirpation or

extinction by unforeseen catastrophic events, either natural (e.g.,

prolonged drought combined with disease outbreak) or human-caused. Pro-

active recovery efforts to lessen the threat of such random events

typically involves the establishment of additional populations.

However, the Service has no evidence to suggest that these taxa have

ever been found beyond the areas they currently occupy. Therefore,

their conservation would not include increasing the number or

distribution of populations beyond the dunes which they currently

inhabit. Because of the low probability of an unforeseen catastrophic

event(s), either natural (e.g., prolonged drought combined with disease

outbreak) or human-caused, taking place and affecting entire

populations or colonies of these taxa, the significance of threat from

such an event is insufficient to warrant listing at this time.

The Service has carefully assessed the best scientific and

commercial information available in the development of this withdrawal

notice. After review and consideration of all information available

regarding the past, present, and future threats, and past and current

conservation efforts by BLM and NPS, the Service has determined that

insufficient evidence of threat exists at this time to warrant listing

of Astragalus lentiginosus var. micans and Astragalus lentiginosus var.

sesquimetralis as threatened under the Act. The Service will continue

to monitor data involving population status, visitor use, vehicle

trespass, the presence of nonnative species (including livestock and

feral burros) or other activities or habitat changes affecting these

two taxa.

References Cited

A complete list of all references cited herein is available upon

request from the Ventura Field Office (see ADDRESSES section).

Authors: The primary authors of this withdrawal notice are Diane

Steeck, Ventura Field Office and Christine Mullen, Nevada State Office

(see ADDRESSES section).

Authority

The authority for this action is section 4(b)(6)(B)(ii) of the

Endangered Species Act of 1973, as amended (16 U.S.C. 1531 et seq.)

List of Subjects in 50 CFR Part 17

Endangered and threatened species, Exports, Imports, Reporting and

recordkeeping requirements, Transportation.

Dated: September 29, 1998.

Jamie Rappaport Clark,

Director, U.S. Fish and Wildlife Service.

[FR Doc. 98-26735 Filed 10-5-98; 8:45 am]

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