Endangered and Threatened Wildlife and Plants; Designation of Critical Habitat for Lepidium papilliferum (Slickspot Peppergrass), 27184-27215 [2011-10753]

Agencies

• Fish and Wildlife Service
• DEPARTMENT OF THE INTERIOR

[Federal Register Volume 76, Number 90 (Tuesday, May 10, 2011)]
[Proposed Rules]
[Pages 27184-27215]
From the Federal Register Online via the Government Printing Office [www.gpo.gov]
[FR Doc No: 2011-10753]



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Vol. 76

Tuesday,

No. 90

May 10, 2011

Part II





Department of the Interior





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Fish and Wildlife Service



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50 CFR Part 17



Endangered and Threatened Wildlife and Plants; Designation of Critical 
Habitat for Lepidium papilliferum (Slickspot Peppergrass); Proposed 
Rule

Federal Register / Vol. 76 , No. 90 / Tuesday, May 10, 2011 / 
Proposed Rules

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DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R1-ES-2010-0071; MO 92210-0-0009]
RIN 1018-AX16


Endangered and Threatened Wildlife and Plants; Designation of 
Critical Habitat for Lepidium papilliferum (Slickspot Peppergrass)

AGENCY: Fish and Wildlife Service, Interior.

ACTION: Proposed rule.

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SUMMARY: We, the U.S. Fish and Wildlife Service, propose to designate 
critical habitat for Lepidium papilliferum (slickspot peppergrass) 
under the Endangered Species Act of 1973, as amended. In total, we are 
proposing to designate 23,374 hectares (57,756 acres) as critical 
habitat for Lepidium papilliferum, in Ada, Elmore, Payette, and Owyhee 
Counties in Idaho.

DATES: To provide us with adequate time to consider your comments, 
comments must be received on or before July 11, 2011. Please note that 
if you are using the Federal eRulemaking Portal (see ADDRESSES section, 
below), the deadline for submitting an electronic comment is 11:59 p.m. 
Eastern Standard Time on this date. We must receive requests for public 
hearings, in writing, at the address shown in the FOR FURTHER 
INFORMATION CONTACT section by June 24, 2011.

ADDRESSES: You may submit comments by one of the following methods:
     Federal eRulemaking Portal: https://www.regulations.gov. In 
the box that reads ``Enter Keyword or ID,'' enter the docket number for 
this proposed rule, which is FWS-R1-ES-2010-0071. Check the box that 
reads ``Open for Comment/Submission,'' and then click the Search 
button. You should see an icon that reads ``Submit a Comment.'' Please 
ensure that you have found the correct rulemaking before submitting 
your comment.
     U.S. mail or hand-delivery: Public Comments Processing, 
Attn: FWS-R1-ES-2010-0071; Division of Policy and Directives 
Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, 
Suite 222; Arlington, VA 22203.
    We will post all comments on https://www.regulations.gov. This 
generally means that we will post any personal information you provide 
us (see the Public Comments section below for more information).

FOR FURTHER INFORMATION CONTACT: Brian Kelly, State Supervisor, U.S. 
Fish and Wildlife Service, Idaho Fish and Wildlife Office, 1387 S. 
Vinnell Way, Room 368, Boise, ID 83709; telephone 208-378-5243; 
facsimile 208-378-5262. If you use a telecommunications device for the 
deaf (TDD), call the Federal Information Relay Service (FIRS) at 800-
877-8339.

SUPPLEMENTARY INFORMATION:

Public Comments

    We intend that any final action resulting from this proposal will 
be based on the best scientific and commercial data available and be as 
accurate and as effective as possible. Therefore, we request comments 
or information from other concerned government agencies, the scientific 
community, industry, or other interested parties concerning this 
proposed rule. We particularly seek comments concerning:
    (1) The reasons why we should or should not designate habitat as 
``critical habitat'' under section 4 of the Endangered Species Act of 
1973, as amended (Act) (16 U.S.C. 1531 et seq.), including whether 
there are threats to Lepidium papilliferum from human activity, the 
degree to which threats from human activity can be expected to increase 
due to the designation, and whether that increase in threats outweighs 
the benefit of designation such that the designation of critical 
habitat may not be prudent.
    (2) Specific information on:
     The amount and distribution of Lepidium papilliferum 
habitat;
     What areas occupied at the time of listing and that 
contain features essential to the conservation of Lepidium papilliferum 
should be included in the designation and why;
     The habitat components (primary constituent elements) 
essential to the conservation of the species, such as specific soil 
characteristics, plant associations, or pollinators, and the quantity 
and spatial arrangement of these features on the landscape needed to 
provide for the conservation of the species;
     What areas not occupied at the time of listing are 
essential for the conservation of the species, if any, and why; and
     Special management considerations or protections that the 
features essential to the conservation of Lepidium papilliferum may 
require, including managing for the potential effects of climate 
change.
    (3) Land use designations and current or planned activities in the 
subject areas and their possible impacts on proposed critical habitat.
    (4) Any probable economic, national security, or other relevant 
impacts of designating any area that may be included in the final 
designation. We are particularly interested in any impacts on small 
entities, and the benefits of including or excluding areas that are 
subject to these impacts.
    (5) Whether the benefits of excluding any particular area from 
critical habitat outweigh the benefits of including that area in 
critical habitat under section 4(b)(2) of the Act, after considering 
both the potential impacts and benefits of the proposed critical 
habitat designation. Under section 4(b)(2) of the Act, we may exclude 
an area from critical habitat if we determine that the benefits of such 
exclusion outweigh the benefits of including that particular area as 
critical habitat, unless failure to designate that specific area as 
critical habitat will result in the extinction of the species. We are 
considering the possible exclusion of areas under private ownership, in 
particular, as we anticipate the benefits of exclusion may outweigh the 
benefits of inclusion in those areas. We therefore request specific 
information on:
     The benefits of including any specific areas in the final 
designation and supporting rationale,
     The benefits of excluding any specific areas from the 
final designation and supporting rationale, and
     Whether any specific exclusions may result in the 
extinction of the species and why (see Exclusions section below).
    (5) The use of Public Land Survey System quarter-quarter sections 
to delineate the proposed critical habitat designation; we used 
quarter-quarter sections in this proposed rule because they are the 
most-commonly-used minimum size and method for delineating land 
ownership boundaries within the range of Lepidium papilliferum.
    (6) Information on the projected and reasonably likely impacts of 
climate change on Lepidium papilliferum and on the critical habitat 
areas we are proposing.
    (7) Whether we could improve or modify our approach to designating 
critical habitat in any way to provide for greater public participation 
and understanding, or to better accommodate public concerns and 
comment.
    Our final determination concerning critical habitat for Lepidium 
papilliferum will take into consideration all written comments we 
receive during the comment period,

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including comments from peer reviewers, comments we receive during any 
public hearing should one be requested, and any additional information 
we receive during the 60-day comment period. All comments will be 
included in the public record for this rulemaking. On the basis of peer 
reviewer and public comments, we may, during the development of our 
final determination, find that areas within the proposed designation do 
not meet the definition of critical habitat, that some modifications to 
the described boundaries are appropriate, or that areas may or may not 
be appropriate for exclusion under section 4(b)(2) of the Act.
    You may submit your comments and materials concerning this proposed 
rule by one of the methods listed in the ADDRESSES section. We will 
post your entire comment--including any personal identifying 
information--on https://www.regulations.gov. If you provide personal 
identifying information, such as your name, street address, phone 
number, or e-mail address, you may request at the top of your document 
that we withhold this information from public review. However, we 
cannot guarantee that we will be able to do so.
    Comments and materials we receive, as well as supporting 
documentation we used in preparing this proposed rule, will be 
available for public inspection on https://www.regulations.gov, or by 
appointment, during normal business hours, at the U.S. Fish and 
Wildlife Service, Idaho Fish and Wildlife Office (see FOR FURTHER 
INFORMATION CONTACT).

Background

    Lepidium papilliferum was listed as a threatened species under the 
Act on October 8, 2009 (74 FR 52014). In this proposed rule, we intend 
to discuss only those topics directly relevant to the designation of 
critical habitat for this species. For more detailed information on the 
genetics and biology of L. papilliferum, please refer to the final 
listing rule published in the Federal Register on October 8, 2009 (74 
FR 52014). Detailed information on L. papilliferum directly relevant to 
designation of critical habitat is discussed under the Primary 
Constituent Elements section below.

Species Information

    Lepidium papilliferum is a small, flowering plant in the mustard 
family (Brassicaceae). The plant grows in unique microsite habitats 
known as slickspots (described below, under ``Ecology and Habitat''), 
which are found within the semiarid sagebrush-steppe ecosystem of 
southwestern Idaho. The species is endemic to this region, known only 
from the Snake River Plain and its adjacent northern foothills (an area 
approximately 145 by 40 kilometers (km) (90 by 25 miles (mi)), or 5,800 
square kilometers (km\2\) (2,250 square miles (mi\2\))), with a 
smaller, disjunct population on the Owyhee Plateau (an area of 
approximately 18 by 19 km (11 by 12 mi), or 342 km\2\ (132 mi\2\)). 
Rangewide, L. papilliferum is associated with slickspots that cover a 
relatively small cumulative area within the larger sagebrush-steppe 
ecosystem. Additionally, although L. papilliferum is found almost 
exclusively in slickspots, very few existing slickspots are occupied by 
L. papilliferum.
    Lepidium papilliferum is herbaceous and relatively low-growing, 
averaging 5 to 20 centimeters (cm) (2 to 8 inches (in)) high, but 
occasionally reaching up to 40 cm (16 in) in height. It is an 
intricately branched, tap-rooted plant, with numerous, small, white, 
four-petalled flowers. Fruits (siliques) are round in outline, 
flattened, and two-seeded (Moseley 1994, pp. 3, 4; Holmgren et al. 
2005, p. 260). The species is monocarpic (it flowers once and then 
dies) and displays two different life history strategies--an annual 
form and a biennial form. The annual form reproduces by flowering and 
setting seed in its first year, and dies within one growing season. The 
biennial life form initiates growth in the first year as a vegetative 
rosette, but does not flower and produce seed until the second growing 
season. The proportion of annuals versus biennials in a population can 
vary greatly (Meyer et al. 2005, p. 15), but in general annuals appear 
to outnumber biennials (Moseley 1994, p. 12).
    Like many short-lived plants growing in arid environments, above-
ground numbers of Lepidium papilliferum individuals can fluctuate 
widely from one year to the next, depending on seasonal precipitation 
patterns (Mancuso and Moseley 1998, p. 1; Meyer et al. 2005, pp. 4, 12, 
15; Palazzo et al. 2005, p. 9; Menke and Kaye 2006a, p. 8; Menke and 
Kaye 2006b, pp. 10, 11; Sullivan and Nations 2009, p. 44). Mancuso and 
Moseley (1998, p. 1) note that sites with thousands of above-ground 
plants one year may have none the next, and vice versa. Above-ground 
plants represent only a portion of the population; the seed bank (a 
reserve of dormant seeds, generally found in the soil) contributes the 
other portion, and in many years constitutes the majority of the 
population (Mancuso and Moseley 1998, p. 1).

Ecology and Habitat

    Lepidium papilliferum gets its common name, slickspot peppergrass, 
from its almost exclusive association with slickspot microsite 
habitats. ``Slickspots'' are visually distinct openings in the 
sagebrush-steppe community characterized by soils with high sodium 
content and distinct clay layers; they tend to be highly reflective and 
light in color, making them easy to detect on the landscape (Fisher et 
al. 1996, p. 3). Within the range of L. papilliferum, slickspots cover 
a relatively small cumulative area within the larger sagebrush-steppe 
ecosystem. For example, an intense field inventory within the U.S. Air 
Force Juniper Butte Range in 2002 found that of the 4,480 ha (11,070 
ac) surveyed, approximately 1 percent (44.1 ha) (109 ac) consisted of 
slickspot microsites; of those slickspots, only 4 percent were occupied 
by individuals of L. papilliferum. It is not known how long slickspots 
take to form, but it is hypothesized to take several thousands of years 
(Nettleton and Peterson 1983, p. 193; Seronko 2006, in litt.). Climate 
conditions that allowed for the formation of slickspots in southwestern 
Idaho are thought to have occurred during a wetter Pleistocene period. 
As slickspots appear to have formed during the Pleistocene and new 
slickspots are not being formed, the loss of a slickspot is considered 
a permanent loss. Some slickspots subjected to only light disturbance 
in the past may apparently be capable of re-forming (Seronko 2006, in 
litt.). Disturbances that alter the physical properties of the soil 
layers, however, such as deep disturbance and the addition of organic 
matter, may lead to destruction and permanent loss of slickspots.
    Several analyses have shown a positive association between above-
ground abundance of Lepidium papilliferum and spring precipitation in 
the same year. More recently, Sullivan and Nations (2009, pp. 30, 41) 
analyzed 18 years of data and found that both plant density and plant 
abundance were positively related to mean monthly precipitation in late 
winter and spring (January through May). This correlation of abundance 
with spring rainfall is important, as it at least partially explains 
annual fluctuations in L. papilliferum population numbers. In contrast, 
precipitation in the fall or early winter may have a negative effect on 
L. papilliferum abundance the following spring (Meyer et al. 2005, p. 
15; Sullivan and Nations 2009, p. 39). It has been suggested this 
negative relationship may be the result of prolonged flooding of the 
slickspot microsites, causing

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subsequent mortality of overwintering biennial rosettes (Meyer et al. 
2005, pp. 15-16).

Threats

    The primary threat factors that affect the habitat and survival of 
Lepidium papilliferum in southwest Idaho include the invasion of 
nonnative annual grasses, such as Bromus tectorum (cheatgrass), and 
increased fire frequency. Bromus tectorum can impact L. papilliferum 
directly through competition, but it also acts indirectly on the 
species by providing continuous fine fuels that contribute to the 
documented increased frequency and extent of wildfires in southwest 
Idaho. Frequent wildfires ultimately result in the conversion of the 
sagebrush-steppe habitat to nonnative annual grasslands, with 
consequent losses of native species diversity and natural ecological 
function. This creates a positive feedback loop between nonnative 
annual grasses and fire, which makes it difficult to separate out the 
effects that each of these threats independently have on L. 
papilliferum.
    Development also poses a threat to Lepidium papilliferum, both 
directly through the destruction of populations and loss of slickspot 
microsites, as well as indirectly through habitat fragmentation. The 
loss of slickspots is a permanent loss of habitat for L. papilliferum, 
because the species is specifically adapted to occupy these unique 
microsite habitats that developed in the Pleistocene era, and new 
slickspots are no longer being formed (Nettleton and Peterson 1983, pp. 
166, 191, 206).
    In addition to wildfire, nonnative plants, and development, 
livestock use poses a secondary threat to Lepidium papilliferum, 
primarily through mechanical damage to individual plants and slickspot 
habitats. Livestock trampling can disrupt the soil layers of 
slickspots, altering slickspot function (Seronko 2004, in litt.; Colket 
2005, p. 34; Meyer et al. 2005, pp. 21-22). Trampling when slickspots 
are dry can lead to mechanical damage to the slickspot soil crust, 
potentially resulting in the invasion of nonnative plants and altering 
the hydrologic function of slickspots. In water-saturated slickspot 
soils, trampling by livestock can break through the restrictive clay 
layer; this is referred to as penetrating trampling (State of Idaho et 
al. 2006, p. 9). Trampling that alters the soil structure and the 
functionality of slickspots (Rengasamy et al. 1984, p. 63; Seronko 
2004, in litt.) likely impacts the suitability of these microsites for 
L. papilliferum. Trampling can also negatively affect the seed bank by 
pushing seeds too deeply into the soil for subsequent successful 
germination and emergence. The current livestock management conditions 
and associated conservation measures address this threat such that it 
does not appear to pose a significant risk to the species at this time, 
but more monitoring information is needed to determine the significance 
of this threat to L. papilliferum rangewide.
    Lepidium papilliferum is primarily an outcrossing species, and 
depends upon a diversity of insect pollinators for more successful 
fruit production and to maintain genetic variability by genetic 
exchange with distant populations. Some of the primary threats 
identified may have indirect effects on L. papilliferum by negatively 
impacting the native insect populations that the species depends on for 
pollination and genetic exchange. Changes in native habitat caused by 
residential or agricultural development, or conversion of the native 
plant community to nonnative species, may impact insect pollinator 
populations by removing specific food sources or habitats required for 
breeding or nesting. In addition, habitat isolation and fragmentation 
resulting from activities such as development or road construction may 
result in decreased pollination of L. papilliferum from distant 
sources, possibly resulting in decreased reproductive potential (e.g., 
lower seed set) and reduced genetic diversity.
    The Owyhee harvester ant was recently identified as a potentially-
important seed predator of Lepidium papilliferum. A native species, the 
harvester ants appear to favor areas dominated by nonnative annual 
grasses, such as Bromus tectorum, and in the wake of disturbance 
factors such as wildfire, these ants are beginning to colonize areas 
that were historically unsuitable for nesting. This expansion is 
increasingly bringing them into contact with L. papilliferum, which 
experiences high rates of seed predation by the ants with potential 
negative consequences for the seed bank and recruitment. Our current 
understanding of how pervasive harvester ant colonies have become 
within the range of L. papilliferum, and their overall significance on 
the long-term viability of the species, is limited due to the short-
term nature of the research so far.
    For a detailed analysis of the threats to Lepidium papilliferum, 
please refer to the final listing rule for the species published 
October 8, 2009 (74 FR 52014).

Previous Federal Actions

    On July 15, 2002, we proposed to list Lepidium papilliferum as 
endangered (67 FR 46441). On January 12, 2007, we published a document 
in the Federal Register withdrawing the proposed rule (72 FR 1622), 
based on a determination at that time that listing was not warranted 
(for a description of Federal actions concerning L. papilliferum 
between the 2002 proposal to list and the 2007 withdrawal, please refer 
to the 2007 withdrawal document). On April 6, 2007, Western Watersheds 
Project filed a lawsuit challenging our decision to withdraw the 
proposed rule to list L. papilliferum. On June 4, 2008, the U.S. 
District Court for the District of Idaho (Court) reversed the decision 
to withdraw the proposed rule, with directions that the case be 
remanded to the Service for further consideration consistent with the 
Court's opinion (Western Watersheds Project v. Kempthorne, Case No. CV 
07-161-E-MHW (D. Idaho)).
    After issuance of the Court's remand order, we published a public 
notification of the reinstatement of our July 15, 2002, proposed rule 
to list Lepidium papilliferum as endangered and announced the reopening 
of a public comment period on September 19, 2008 (73 FR 54345). To 
ensure that our review of the species' status was complete, we 
announced another reopening of the comment period on March 17, 2009, 
for a period of 30 days (74 FR 11342). On October 8, 2009, we published 
a final rule (74 FR 52014) listing L. papilliferum as a threatened 
species throughout its range.

Critical Habitat

Background

    Critical habitat is defined in section 3 of the Act as:
    (i) The specific areas within the geographical area occupied by the 
species, at the time it is listed in accordance with the Act, on which 
are found those physical or biological features.
    (I) Essential to the conservation of the species, and
    (II) Which may require special management considerations or 
protection; and
    (ii) Specific areas outside the geographical area occupied by the 
species at the time it is listed, upon a determination that such areas 
are essential for the conservation of the species.
    Conservation, as defined under section 3 of the Act, means to use 
and the use of all methods and procedures that are necessary to bring 
an

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endangered or threatened species to the point at which the measures 
provided under the Act are no longer necessary. Such methods and 
procedures include, but are not limited to, all activities associated 
with scientific resources management such as research, census, law 
enforcement, habitat acquisition and maintenance, propagation, live 
trapping, and transplantation, and, in the extraordinary case where 
population pressures within a given ecosystem cannot be otherwise 
relieved, may include regulated taking.
    Critical habitat receives protection under section 7 of the Act 
through the prohibition against Federal agencies carrying out, funding, 
or authorizing the destruction or adverse modification of critical 
habitat. Section 7(a)(2) requires consultation on Federal actions that 
may affect critical habitat. The designation of critical habitat does 
not affect land ownership or establish a refuge, wilderness, reserve, 
preserve, or other conservation area. Such designation does not allow 
the government or public to access private lands. Such designation does 
not require implementation of restoration, recovery, or enhancement 
measures by non-Federal landowners. Where a landowner seeks or requests 
Federal agency funding or authorization for an action that may affect a 
listed species or critical habitat, the consultation requirements of 
section 7(a)(2) would apply, but even in the event of a destruction or 
adverse modification finding, the Federal action agency and the 
applicant's obligation is not to restore or recover the species, but to 
implement reasonable and prudent alternatives to avoid destruction or 
adverse modification of critical habitat.
    For inclusion in a critical habitat designation, the habitat within 
the geographical area occupied by the species at the time it was listed 
must contain the primary constituent elements (PCEs) essential to the 
conservation of the species, and be included only if those features may 
require special management considerations or protection. Critical 
habitat designations identify, to the extent known using the best 
scientific data available, habitat areas that provide essential life-
cycle needs of the species (areas on which are found the PCEs laid out 
in the appropriate quantity and spatial arrangement for the 
conservation of the species). Under the Act and regulations at 50 CFR 
424.12, we can designate critical habitat in areas outside the 
geographical area occupied by the species at the time it is listed only 
when we determine that those areas are essential for the conservation 
of the species and that a designation limited to those areas occupied 
at the time of listing would be inadequate to ensure the conservation 
of the species.
    Section 4 of the Act requires that we designate critical habitat on 
the basis of the best scientific data available. Further, our Policy on 
Information Standards under the Endangered Species Act (published in 
the Federal Register on July 1, 1994 (59 FR 34271)), the Information 
Quality Act (section 515 of the Treasury and General Government 
Appropriations Act for Fiscal Year 2001 (Pub. L. 106-554; 114 Stat. 
2763A-153-54)), and our associated Information Quality Guidelines 
(available online at https://www.fws.gov/informationquality/topics/IQAguidelines-final82307.pdf), provide criteria, establish procedures, 
and provide guidance to ensure that our decisions are based on the best 
scientific data available. They require our biologists, to the extent 
consistent with the Act and with the use of the best scientific data 
available, to use primary and original sources of information as the 
basis for recommendations to designate critical habitat.
    When we are determining which areas should be designated as 
critical habitat, our primary source of information is generally the 
information developed during the listing process for the species. 
Additional information sources may include the recovery plan for the 
species (if available), articles in peer-reviewed journals, 
conservation plans developed by States and counties, scientific status 
surveys and studies, biological assessments, or other unpublished 
materials, including expert opinion or personal knowledge.
    Habitat is often dynamic, and species may move from one area to 
another over time. In particular, we recognize that climate change may 
cause changes in areas of occupied habitat. In the Pacific Northwest, 
regionally averaged temperatures have risen 0.8 degrees Celsius (C) 
(1.5 degrees Fahrenheit (F)) over the last century (as much as 2 
degrees C (4 degrees F) in some areas), and are projected to increase 
by another 1.5 to 5.5 degrees C (3 to 10 degrees F) over the next 100 
years (Mote et al. 2003, p. 54; Karl et al. 2009, p. 135). Arid regions 
such as the Great Basin where Lepidium papilliferum occurs are likely 
to become hotter and drier, fire frequency is expected to accelerate, 
and fires may become larger and more severe (Brown et al. 2004, pp. 
382-383; Neilson et al. 2005, p. 150; Chambers and Pellant 2008, p. 31; 
Karl et al. 2009, p. 83). Under projected future temperature 
conditions, the cover of sagebrush in the Great Basin region is 
anticipated to be dramatically reduced (Neilson et al. 2005, p. 154). 
Warmer temperatures and greater concentrations of atmospheric carbon 
dioxide create conditions favorable to the invasive annual grass Bromus 
tectorum, and perpetuate the positive feedback cycle between annual 
grasses and fire frequency that poses a significant threat to the 
sagebrush matrix habitat of L. papilliferum (Chambers and Pellant 2008, 
p. 32; Karl et al. 2009, p. 83).
    The direct, long-term impact from climate change to the habitat of 
Lepidium papilliferum is yet to be determined. Under the current 
climate-change projections discussed above, we anticipate that future 
climatic conditions will favor further invasion by Bromus tectorum, 
that fire frequency will continue to increase, and that the extent and 
severity of fires may increase as well, further changing the species 
composition of southwest Idaho's sagebrush-steppe habitat.
    Although the Intergovernmental Panel on Climate Change (IPCC) 
projects that the changes to the global climate system in the 21st 
century will likely be greater than those observed in the 20th century 
(IPCC 2007, p. 45), there are, nonetheless, limitations to our ability 
to estimate the scope or magnitude of the effects. Therefore, we 
recognize that critical habitat designated at a particular point in 
time may not include all of the habitat areas that we may later 
determine necessary for the recovery of the species. For these reasons, 
a critical habitat designation does not signal that habitat outside the 
designated area is unimportant or may not be required for recovery of 
the species.
    Areas that are important to the conservation of the species, but 
are outside the critical habitat designation, will continue to be 
subject to conservation actions we implement under section 7(a)(1) of 
the Act. Those areas outside the critical habitat designation that 
support populations are also subject to the regulatory protections 
afforded by the section 7(a)(2) jeopardy standard, as determined on the 
basis of the best available scientific information at the time of the 
agency action. Federally funded or permitted projects affecting listed 
species outside their designated critical habitat areas may still 
result in jeopardy findings in some cases. Similarly, critical habitat 
designations made on the basis of the best available information at the 
time of designation will not control the direction and substance of 
future recovery plans, habitat conservation plans (HCPs), or other 
species conservation planning efforts if new information available at 
the time of

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these planning efforts calls for a different outcome.

Methods

    As required by section 4(b)(2) of the Act, in developing this 
proposed rule we used the best scientific data available in determining 
those specific areas within the geographical area occupied at the time 
of listing that contain the features essential to the conservation of 
Lepidium papilliferum and that may require special management 
considerations or protection.
    We reviewed available information that pertains to the habitat 
requirements of this species. These sources of information included, 
but were not limited to, data used to complete the final rule to list 
the species (74 FR 52014; October 8, 2009); information from biological 
surveys, peer reviewed articles, various agency reports and databases 
for or by the Idaho Natural Heritage Program (INHP), U.S. Bureau of 
Land Management (BLM), Idaho Army National Guard, State of Idaho, U.S. 
Air Force, and nongovernmental cooperators; discussions with species 
experts; and data and information presented in academic research 
theses. Additionally, we utilized regional Geographic Information 
System (GIS) data (such as species occurrence data, land use, 
topography, aerial imagery, soil data, and land ownership maps) for 
area calculations and mapping.
    The long-term probability of the survival and recovery of Lepidium 
papilliferum is dependent upon protecting existing population sites of 
sufficient quality and viability to contribute meaningfully to the 
conservation of the species; maintaining ecological function within 
these sites, including preserving the integrity of the slickspot soils 
and connectivity within and between populations in close geographic 
proximity to one another (to facilitate pollinator activity); and 
keeping these areas free of major habitat-disturbing activities, 
including the establishment of invasive, nonnative plant species and 
frequent wildfire. Because slickspots cover a relatively small 
cumulative area within the larger sagebrush-steppe matrix, we did not 
restrict the designation to individual occupied slickspots, but 
included some adjacent sagebrush-steppe habitat to provide for 
ecosystem function. This contiguous habitat provides the requisite PCEs 
for L. papilliferum, including native flowering plants and habitat to 
support pollinators, and additionally provides the essential feature of 
habitat free from disturbances, such as invasive species, development, 
and recreation. The areas we are proposing to designate as critical 
habitat were all occupied at the time of listing, and provide physical 
and biological features essential for the conservation of L. 
papilliferum that may require special management considerations or 
protection. We do not propose to designate areas outside of the 
geographical area presently occupied by the species.
    Our first step in delineating proposed critical habitat units was 
to identify areas that provide for the conservation of Lepidium 
papilliferum within the three physiographic regions where the species 
was known to occur at the time of listing (74 FR 52020; October 8, 
2009). These areas include the Boise Foothills, the Snake River Plain 
and its adjacent northern foothills, and a single disjunct population 
on the Owyhee Plateau. We are proposing to designate critical habitat 
in all three physiographic regions to conserve the genetic variability 
represented by L. papilliferum across its range and because these areas 
are representative of the entire known historical geographic 
distribution of the species (50 CFR 424.12(b)(5)).
    We then identified areas within these geographic units that were 
occupied by Lepidium papilliferum at the time of listing utilizing the 
element occurrence (EO) data provided to us by the Idaho Natural 
Heritage Program (INHP), and information used in the final rule to list 
Lepidium papilliferum published in the Federal Register on October 8, 
2009 (74 FR 52014). Element occurrences of L. papilliferum are defined 
by grouping occupied slickspots that occur within 1 km (0.6 mi) of each 
other; all occupied slickspots within a 1-km (0.6-mi) distance of 
another occupied slickspot are aggregated into a single EO. The 
definition of a single EO is based on the distance over which 
individuals of L. papilliferum are believed to be capable of genetic 
exchange through insect-mediated pollination (Colket and Robertson 
2006, pp. 1-2). INHP assigned to each EO an identifying number and a 
qualitative rank based on measures of population size and habitat 
quality. Using the EO area ranking system developed by the INHP, we 
evaluated specific areas to propose for designation as critical habitat 
(see Criteria Used to Identify Critical Habitat, below). The ranking 
given to each area takes into account those features that are essential 
to L. papilliferum, including the presence of slickspots, habitat 
conditions within and surrounding the area, and the conditions of the 
surrounding landscape features necessary to support pollination and 
other life-history requirements. Each EO for L. papilliferum is given a 
ranking of A, B, C, D, E, F, H, or X by the INHP; higher rankings (the 
highest rank would be an ``A'') indicate sites with greater habitat 
quality and larger population sizes, which we infer are more likely to 
persist and sustain the species. As of February 2009, there were no A-
ranked EOs of L. papilliferum. Rankings of B, C, and D indicate a 
decreasing continuum of detectable plants, native plant community, 
habitat condition, and overall landscape context within 1 km (0.6 mi) 
of occupied slickspots, with a B ranking signifying a greater number of 
plants and better habitat conditions and a D ranking signifying few 
plants and poor conditions. Areas ranked E are those records with 
confirmed L. papilliferum presence but for which no additional habitat 
information is available. Areas ranked H indicate historical 
occurrences, X rankings connote extirpated occurrences, and F rankings 
indicate areas where no L. papilliferum individuals were found when 
last visited by a qualified surveyor.
    Critical habitat boundaries were initially determined based on the 
minimum delineation of EO areas. Using GIS, we included an area of 
approximately 250 meter (m) (820 feet (ft)) around each EO to provide 
the PCEs for the species, including habitat of sufficient quantity and 
quality to support pollinators of Lepidium papilliferum in occupied 
slickspots. This areal extent was chosen to provide the minimum area 
needed to sustain an active pollinator community for L. papilliferum. 
This distance is not meant to capture all habitat that is potentially 
used by pollinators, but it is meant to capture a sufficient area to 
allow for pollinators to nest, feed, and reproduce in habitat that is 
adjacent and connected to L. papilliferum EOs. Although the species is 
served by a variety of pollinators, we delineated this pollinator-use 
area based on one of L. papilliferum's important pollinators with a 
relatively limited flight distance, the solitary bee, assuming that 
potential pollinators with long-range flight capabilities would be 
capable of using this habitat as well. Research suggests that solitary 
bees have fairly small foraging distances (Steffan-Dewenter et al. 
2002, pp. 1427-1429; Gathmann and Tscharntke 2002, p. 762); a study by 
Gathmann and Tscharntke suggested a maximum foraging range between 150 
and 600 m (495 and 1,970 ft). Based on this data, we chose 250 m (820 
ft) as a reasonable mid-range estimate of the distance needed to 
provide sufficient

[[Page 27189]]

habitat for the pollinator community. As noted, many other insects also 
contribute to the pollination of L. papilliferum, and some of these 
insects may travel greater distances than solitary bees; however, these 
pollinators may also find habitat within 250 m (820 ft) of L. 
papilliferum EOs. We did not delineate a pollinator use area larger 
than 250 m (820 ft) around L. papilliferum EOs, because that could 
include habitats that may not directly contribute to the survival or 
recovery of the species. In addition to supporting the pollinator 
community, this area surrounding EOs of L. papilliferum provides the 
essential feature of habitat free from disturbance, such as development 
and recreation, for the species.
    Using GIS, we intersected the 250-m (820-ft) buffered EOs with a 
quarter-quarter section shapefile based on the Public Land Survey 
System. The Public Land Survey System is a rectangular survey system 
commonly used in the western United States that divides the land into 
6-mile square townships (equivalent to 1,554 ha), which are then 
further subdivided into 1-mile square sections (259 ha). These sections 
may be surveyed into smaller squares by repeated halving and 
quartering; a quarter section is 160 ac (65 ha), and the smallest unit 
normally utilized is a ``quarter-quarter section,'' equal in size to 40 
ac (16 ha) (about \1/16\ of a square mile, or 400 m across). Quarter-
quarter sections that contained delineated EOs and surrounding buffers 
were initially identified as proposed critical habitat. We chose this 
strategy because, in our judgment, this scale of analysis is the 
appropriate scale for defining the critical habitat boundaries of this 
particular species. We based our determination to use this scale of 
analysis on the following reasons: (1) Quarter-quarter sections are the 
most-commonly-used minimum size and method for delineating land 
ownership boundaries within the range of Lepidium papilliferum; (2) the 
Public Land Survey System is a commonly-used method in Idaho and the 
sections are easily identified on standard maps, which will assist the 
public and land management agencies in easily identifying proposed 
critical habitat areas; (3) quarter-quarter section boundaries are 
commonly used for partitioning lands for management purposes such as 
livestock allotment boundaries; and (4) quarter-quarter section 
descriptions minimize the number of coordinates necessary to define the 
shapes of the critical habitat units, and avoid a false sense of 
precision that might be inferred from the use of other mapping tools; 
we would not consider mapping on a finer scale to represent reliable 
data with regard to location information.

Primary Constituent Elements (PCEs)

    In accordance with subsections 3(5)(A)(i) and 4(b)(1)(A) of the Act 
and our implementing regulations at 50 CFR 424.12, in determining those 
areas within the geographical area occupied by the species at the time 
of listing to propose as critical habitat, we consider the physical or 
biological features essential to the conservation of the species that 
may require special management considerations or protection. These may 
include, but are not limited to:
    (1) Space for individual and population growth and for normal 
behavior;
    (2) Food, water, air, light, minerals, or other nutritional or 
physiological requirements;
    (3) Cover or shelter;
    (4) Sites for breeding, reproduction, or rearing (or development) 
of offspring; germination, or seed dispersal; and generally
    (5) Habitats that are protected from disturbance or are 
representative of the historic geographical and ecological 
distributions of a species.
    We derived the specific PCEs essential to the conservation of 
Lepidium papilliferum based on the known biological needs of the 
species. We consider the physical or biological features essential to 
the conservation of L. papilliferum to be those PCEs laid out in the 
appropriate quantity and spatial arrangement to provide for the 
conservation of the species. All areas proposed as critical habitat for 
L. papilliferum are currently occupied, were occupied at the time of 
listing, and are within the species' historical geographic range.
    With rare exception, Lepidium papilliferum is known only to occur 
in slickspot habitat microsites scattered within the greater semiarid 
sagebrush-steppe ecosystem of southwestern Idaho. The restricted 
distribution of L. papilliferum is likely due to its adaptation to the 
specific conditions within these slickspot habitats. Slickspots are 
distinguished from the surrounding sagebrush habitat as having the 
following characteristics: microsites where water pools when rain falls 
(Fisher et al. 1996, pp. 2, 4); sparse native vegetation; distinct soil 
layers with a columnar or prismatic structure, higher alkalinity and 
clay content, and natric (sodic, high sodium) properties (Fisher et al. 
1996, pp. 15-16; Meyer and Allen 2005, pp. 3-5, 8; Palazzo et al. 2008, 
p. 378); and reduced levels of organic matter and nutrients due to 
lower biomass production (Meyer and Quinney 1993, pp. 3, 6; Fisher et 
al. 1996, p. 4). Although the low permeability of slickspots appears to 
help hold moisture (Moseley 1994, p. 8), once the thin crust dries out, 
the survival of L. papilliferum seedlings depends on the ability of the 
plant to extend the taproot into the argillic horizon (soil layer with 
high clay content) to extract moisture from the deeper natric zone 
(Fisher et al. 1996, p. 13).
    Ecologically functional slickspots have the following three primary 
layers: the surface silt layer, the middle restrictive layer, and an 
underlying moist clay layer. Although slickspots can appear homogeneous 
on the surface, the actual depth of the silt and restrictive layer can 
vary throughout the slickspot (Meyer and Allen 2005, Tables 9, 10, and 
11). The top two layers (surface silt and restrictive) of slickspots 
are normally very thin; the surface silt layer varies in thickness from 
a few mm to 3 cm (0.1 to 1.2 in) in slickspots known to support 
Lepidium papilliferum, and the restrictive layer varies in thickness 
from 1 to 3 cm (0.4 to 1.2 in) (Meyer and Allen 2005, p. 3). Fisher et 
al. (1995, p. 4) describe the smooth surface layer of slickspots as 
crustlike, with prominent vesicular pores. Below the surface layer, the 
soil clay content increases abruptly and creates a strongly-structured, 
finely-textured boundary (horizon) formed by the concentration of 
silicate clay materials, known as an argillic horizon. Slickspot soil 
profiles are distinctive and distinguished from the surrounding soil 
matrix by very thin surface layers that form prominently vesicular 
crusts, natric-like argillic horizons that occur just below the soil 
surface, and by increasingly saline and sodic conditions with depth 
(Fisher et al. 1995, pp. 11, 16). Disturbances that alter the physical 
properties of slickspot soil layers, such as deep disturbance and the 
addition of organic matter, may lead to destruction and permanent loss 
of slickspots. Slickspot soils are especially susceptible to mechanical 
disturbances when wet (Rengasmy et al. 1984, p. 63; Seronko 2004, in 
litt.). Such disturbances disrupt the soil layers important to L. 
papilliferum seed germination and seedling growth, and alter 
hydrological function.
    The biological soil crust, also known as a microbiotic crust or 
cryptogamic crust, is another component of quality habitat for Lepidium 
papilliferum. Such crusts are commonly found in semiarid

[[Page 27190]]

and arid ecosystems, and are formed by living organisms, primarily 
bryophytes, lichens, algae, and cyanobacteria, that bind together 
surface soil particles (Moseley 1994, p. 9; Johnston 1997, p. 4). 
Microbiotic crusts play an important role in stabilizing the soil and 
preventing erosion, increasing the availability of nitrogen and other 
nutrients in the soil, and regulating water infiltration and 
evaporation levels (Johnston 1997, pp. 8-10). In addition, an intact 
crust appears to aid in preventing the establishment of invasive plants 
(Brooks and Pyke 2001, p. 4, and references therein; see also Serpe et 
al. 2006, pp. 174, 176). These crusts are sensitive to disturbances 
that disrupt crust integrity, such as compression due to livestock 
trampling or off-road vehicle (ORV) use, and are also vulnerable to 
damage by fire. Recovery from disturbance is possible but occurs very 
slowly (Johnston 1997, pp. 10-11).
    The native, semiarid sagebrush-steppe habitat of southwestern Idaho 
where Lepidium papilliferum is found can be divided into two plant 
associations, each dominated by the shrub Artemisia tridentata ssp. 
wyomingensis (Wyoming big sagebrush): (1) A. tridentata ssp. 
wyomingensis-Achnatherum thurberianum (formerly Stipa thurberiana) 
(Thurber's needlegrass); and (2) A. tridentata ssp. wyomingensis-
Agropyron spicatum (bluebunch wheatgrass) habitat types. The perennial 
bunchgrasses Poa secunda (Sandberg's bluegrass) and Sitanion hysrix 
(bottlebrush squirreltail) are commonly found in the understory of 
these habitats, and the species Artemisia tridentata ssp. tridentata 
(basin big sagebrush), Chrysothamnus nauseosus (grey rabbitbrush), 
Chrysothamnus viridiflorus (green rabbitbrush), Eriogonum strictum 
(strict buckwheat), Purshia tridentata (bitterbrush), and Tetradymium 
glabrata (little-leafed horsebrush) form a lesser component of the 
shrub community. Under relatively undisturbed conditions, the 
understory is populated by a diversity of perennial bunchgrasses and 
forbs, including species such as Achnatherum (formerly Oryzopsis) 
hymenoides (Indian ricegrass), Achillea millefolium (common yarrow), 
Phacelia heterophylla (varileaf phacelia), Astragalus purshii (Pursh's 
milkvetch), Phlox longifolia (longleaf phlox), and Aristida purpurea 
var. longiseta (purple threeawn).
    Lepidium papilliferum is primarily an outcrossing species requiring 
pollen from separate plants for more successful fruit production; it 
exhibits low seed set in the absence of insect pollinators (Robertson 
2003, p. 5; Robertson and Klemash 2003, p. 339; Robertson and Ulappa 
2004, p. 1707; Billinge and Robertson 2008, pp. 1005-1006). Lepidium 
papilliferum is capable of self-pollinating, however, with a selfing 
rate (rate of self-pollination) of 12 to 18 percent (Billinge 2006, p. 
40; Robertson et al. 2006a, p. 40).
    Known Lepidium papilliferum insect pollinators include several 
families of bees (Hymenoptera), including Apidae, Halictidae, 
Sphecidae, and Vespidae; beetles (Coleoptera), including Dermestidae, 
Meloidae, and Melyridae; flies (Diptera), including Bombyliidae, 
Syrphidae, and Tachinidae; and others (Robertson and Klemash 2003, p. 
336; Robertson et al. 2006b, p. 6). Seed set does not appear to be 
limited by the abundance of pollinators (Robertson et al. 2004, p. 14). 
However, studies have shown a strong positive correlation between 
insect diversity and the number of L. papilliferum flowering at a site 
(Robertson and Hannon 2003, p. 8). Measurement of fruit set per visit 
revealed considerable variability in the effectiveness of pollination 
by different types of insects. Since L. papilliferum has a wide array 
of pollinators, general pollinator management practices for 
conservation of pollinators should be practiced at sites designated as 
critical habitat. These practices include ``a diversity of native 
plants whose blooming times overlap to provide flowers for foraging 
throughout the seasons; nesting and egg-laying sites, with appropriate 
nesting materials; sheltered, undisturbed places for hibernation and 
overwintering; and a landscape free of poisonous chemicals'' (Shepherd 
et al. 2003, pp. 49-50). An intact native sagebrush community, as 
opposed to a monoculture of nonnative annual grasslands such as Bromus 
tectorum, is more likely to support a wider array of pollinators. Many 
pollinators depend on native plants and may be unable to access 
resources from introduced species; many bees, for example, not only 
require large numbers of flowers to provide nectar and pollen, but also 
need a variety of flowering plants to sustain them throughout the 
growing season (Kearns and Inouye 1997, p. 298).
    To ensure that sufficient habitat and a diversity of native 
flowering plants are available to support the pollinator community 
required for the viability of Lepidium papilliferum populations, we 
determined that each EO should be surrounded by a minimum pollinator-
use area extending 250 m (820 ft) from the periphery. We chose this 
extent as a reasonable estimate of the area needed to sustain an active 
pollinator community for L. papilliferum (see Methods, above). The 
areas proposed as critical habitat will ensure maintenance and 
continuity of foraging habitats for insect pollinators adjacent to 
occupied slickspots, which helps to increase seed viability and 
production and is essential for maintaining genetic diversity in the 
species over the long term. Additionally, the provision of sufficient 
native sagebrush-steppe habitat protects L. papilliferum from wildfire, 
nonnative plant invasions, and colonization by harvester ants, and it 
helps to maintain local ecosystem characteristics within the larger 
landscape, which are crucial for protecting the species and its seed 
bank. The seed bank is an essential feature of L. papilliferum's 
biology because it provides the species with resilience in the face of 
stochastic impacts and variation in environmental conditions.
    All areas designated as critical habitat for Lepidium papilliferum 
were occupied at the time of listing, are within the species' 
historical geographic range, and provide sufficient PCEs to support at 
least one life-history function. Based on the above needs and our 
current knowledge of the life history, biology, and ecology of the 
species and the habitat requirements for sustaining the essential life 
history functions of the species, we have determined that Lepidium 
papilliferum's PCEs include:
    (1) Ecologically-functional microsites or ``slickspots'' that are 
characterized by:
    (a) A high sodium and clay content, and a three-layer soil 
horizonation sequence, which allows for successful seed germination, 
seedling growth, and maintenance of the seed bank. The surface horizon 
consists of a thin, silty, vesicular, pored (small cavity) layer that 
forms a physical crust (the silt layer). The subsoil horizon is a 
restrictive clay layer with an abruptic (referring to an abrupt change 
in texture) boundary with the surface layer, that is natric or natric-
like in properties (a type of argillic (clay-based) horizon with 
distinct structural and chemical features) (the restrictive layer). The 
second argillic subsoil layer (that is less distinct than the upper 
argillic horizon) retains moisture through part of the year (the moist 
clay layer); and
    (b) Sparse vegetation with low to moderate introduced, invasive, 
nonnative plant species cover.
    (2) Relatively-intact, native Artemisia tridentata ssp. 
wyomingensis (Wyoming big sagebrush) vegetation assemblages, 
represented by native bunchgrasses, shrubs, and forbs, within 250 m 
(820 ft) of Lepidium papilliferum element occurrences to protect 
slickspots and Lepidium papilliferum from disturbance

[[Page 27191]]

from wildfire, slow the invasion of slickspots by nonnative species and 
native harvester ants, and provide the habitats needed by L. 
papilliferum's pollinators.
    (3) A diversity of native plants whose blooming times overlap to 
provide pollinator species with sufficient flowers for foraging 
throughout the seasons and to provide nesting and egg-laying sites; 
appropriate nesting materials; and sheltered, undisturbed places for 
hibernation and overwintering of pollinator species. In order for 
genetic exchange of Lepidium papilliferum to occur, pollinators must be 
able to move freely between slickspots. Alternative pollen and nectar 
sources (other plant species within the surrounding sagebrush 
vegetation) are needed to support pollinators during times when 
Lepidium papilliferum is not flowering, when distances between 
slickspots are large, and in years when L. papilliferum is not a 
prolific flowerer.
    (4) Sufficient pollinators for successful fruit and seed 
production, particularly pollinator species of the sphecid and vespid 
wasp families, species of the bombyliid and tachnid fly families, 
honeybees, and halictid bee species, most of which are solitary insects 
that nest outside of slickspots in the surrounding sagebrush-steppe 
vegetation, both in the ground and within the vegetation.
    The space for individual and population growth is provided by PCEs 
1, 2, and 3; the need for food, water, air, light, minerals, or other 
physiological requirements is provided by PCEs 1 and 2; the need for 
cover and shelter is met by PCEs 1 and 2; sites for reproduction, 
germination, and seed dispersal are provided by PCEs 1, 2, 3, and 4; 
and habitat free from disturbance is met by PCE 2. All of the above 
described PCEs do not have to occur simultaneously within a unit for 
the unit to constitute critical habitat for Lepidium papilliferum. All 
units and subunits proposed in this rule as critical habitat contain at 
least one of the PCEs to provide for one or more of the life-history 
functions of L. papilliferum.

Special Management Considerations or Protection

    Within the geographical area occupied by the species at the time it 
was listed, section 3(5)(A) of the Act defines critical habitat as 
those specific areas on which are found those physical or biological 
features essential to the conservation of the species and that may 
require special management considerations or protection. Accordingly, 
when designating critical habitat, we assess whether the PCEs within 
the areas occupied at the time of listing may require special 
management consideration or protections.
    A detailed discussion of the threats affecting the physical and 
biological features essential to the conservation of Lepidium 
papilliferum, and that may require special management consideration or 
protection, can be found in the final listing rule published in the 
Federal Register on October 8, 2009 (74 FR 52014). The primary threats 
to the PCEs for L. papilliferum include the following direct and 
indirect effects: The current wildfire regime (i.e., increasing 
frequency, size, and duration), invasive, nonnative plant species 
(e.g., Bromus tectorum), and habitat loss and fragmentation due to 
agricultural and urban development. One of the indirect threats 
experienced by L. papilliferum is the negative impact on insect 
pollinators caused by conversion and fragmentation of native habitats 
due to invasive, nonnative plant species and various forms of 
development. Another indirect threat is the potential increase in seed 
predation by harvester ants resulting from the conversion of sagebrush-
steppe to nonnative annual grasses such as B. tectorum. Livestock pose 
a threat to L. papilliferum, primarily through mechanical damage to 
individual plants and slickspot habitats; however, current livestock 
management conditions and associated conservation measures address this 
potential threat such that it does not pose a significant risk to the 
viability of the species as a whole. Other, less significant factors 
that have the potential to impact the species include the effects from 
rangeland revegetation projects, wildfire management practices, 
recreation, and military use.

Current Wildfire Regime

    The current wildfire regime and invasive, nonnative plant species 
were cited in the final listing rule as the primary cause for the 
decline of Lepidium papilliferum. The invasion of nonnative plant 
species, particularly annual grasses such as Bromus tectorum and 
Taeniatherum caput-medusae (medusahead), has contributed to increasing 
the amount and continuity of fine fuels across the landscape, and as a 
result, the wildfire frequency interval has been shortened from between 
60 to 110 years historically to less than 5 years in many areas of the 
sagebrush-steppe ecosystem at present (Wright and Bailey 1982, p. 158; 
Billings 1990, pp. 307-308; Whisenant 1990, p. 4; USGS 1999, in litt., 
pp. 1-9; West and Young 2000, p. 262). These wildfires tend to be 
larger and burn more uniformly than those that occurred historically, 
resulting in fewer patches of unburned vegetation, which can affect the 
post-fire recovery of native sagebrush-steppe vegetation (Whisenant 
1990, p. 4). The result of this altered wildfire regime has been the 
conversion of vast areas of the former sagebrush-steppe ecosystem to 
nonnative annual grasslands (USGS 1999, in litt., pp. 1-9). Frequent 
wildfires can also promote soil erosion and sedimentation (Bunting et 
al. 2003, p. 82) in arid environments such as the sagebrush-steppe 
ecosystem. Increased sedimentation can result in a silt layer that is 
too thick for optimal L. papilliferum germination (Meyer and Allen 
2005, pp. 6-7).
    I. Several researchers have noted signs of increased habitat 
degradation for Lepidium papilliferum, most notably in terms of exotic 
species cover and wildfire frequency (e.g., Moseley 1994, p. 23; Menke 
and Kaye 2006b, p. 19; Colket 2008, pp. 33-34), but only recently have 
analyses demonstrated a statistically significant, negative 
relationship between the degradation of habitat quality, both within 
slickspot microsites and in the surrounding sagebrush-steppe matrix, 
and the abundance of L. papilliferum. Sullivan and Nations (2009, pp. 
114-118, 137) found a consistent, statistically significant, negative 
correlation between wildfire and the abundance of L. papilliferum 
across its range. Their analysis of 5 years of Habitat Integrity and 
Population (HIP) monitoring data indicated that L. papilliferum 
``abundance was lower within those slickspot [sic] that had previously 
burned'' (Sullivan and Nations 2009, p. 137), and the relationship 
between L. papilliferum abundance and fire is reported as ``relatively 
large and statistically significant,'' regardless of the age of the 
fire or the number of past fires (Sullivan and Nations 2009, p. 118). 
The nature of this relationship was not affected by the number of fires 
that may have occurred in the past; whether only one fire had occurred 
or several, the association with decreased abundance of L. papilliferum 
was similar (Sullivan and Nations 2009, p. 118).
    Special management to protect the proposed critical habitat areas 
and the features essential to the conservation of Lepidium papilliferum 
from the effects of the current wildfire regime may include preventing 
or restricting the establishment of invasive, nonnative plant species, 
post-wildfire restoration with native plant species, and reducing the 
likelihood of wildfires affecting the nearby plant community 
components. Local fire agencies can achieve the latter

[[Page 27192]]

by providing a rapid response or mutual support agreement for wildfire 
control.

Invasive, Nonnative Plant Species

    The conversion of sagebrush-steppe habitat to nonnative annual 
grasslands over the past several decades has reduced or degraded 
suitable habitat for Lepidium papilliferum, in addition to fragmenting 
and isolating extant occupied areas. There are two primary ways for 
invasive, nonnative plants to become established in L. papilliferum 
habitats, through natural spreading (unseeded) or revegetation projects 
(seeded). The rates at which nonnative unseeded species are spreading, 
oftentimes into relatively intact habitats, is of major concern to 
natural resource managers. Invasive, nonnative plants can alter various 
attributes of ecosystems including geomorphology, wildfire regime, 
hydrology, microclimate, nutrient cycle, and productivity (for a 
summary see Dukes and Mooney 2003, entire). Additionally, these 
invasive, nonnative plants can negatively affect native plants, 
including rare plants like L. papilliferum, through competitive 
exclusion, niche displacement, hybridization, and competition for 
pollinators; examples of these negative effects are widespread among 
different taxa, locations, and ecosystems (D'Antonio and Vitousek 1992, 
pp. 63-87; Olson 1999, p. 5; Mooney and Cleland 2001, p. 1). Recent 
analyses have revealed a significant, negative association between the 
presence of weedy species and the abundance or density of L. 
papilliferum, to the point that L. papilliferum may be excluded from 
slickspots (Sullivan and Nations 2009, pp. 109-112). Although the 
specific mechanisms are not well understood, some of these plants, such 
as Agropyrum cristatum (crested wheatgrass) and Bromus tectorum, are 
strong competitors in this arid environment for such limited resources 
as moisture, which tends to be concentrated in slickspots (Pyke and 
Archer 1991, p. 4; Moseley 1994, p. 8; Lesica and DeLuca 1998, p. 4), 
at least in the subsurface soils (Fisher et al. 1996, pp. 13-16).
    Special management to protect the features essential to the 
conservation of Lepidium papilliferum in the areas proposed as critical 
habitat from the effects of invasive, nonnative unseeded plant species 
may include the following: (1) protecting remnant blocks of native 
vegetation, (2) educating the public about invasive, nonnative species, 
(3) supporting research and funding for nonnative plant species 
control, (4) preventing or restricting the establishment of nonnative 
plant species, (5) washing vehicles prior to any travel into areas 
containing L. papilliferum, (6) quarantining livestock prior to 
entering allotments containing L. papilliferum, and (7) reducing the 
likelihood of wildfires.

Livestock Use

    The most visible effect to Lepidium papilliferum and its habitat 
from livestock use is through trampling impacts. Livestock trampling 
can affect the fragile soil layers of slickspots (Colket 2005, p. 34; 
Meyer et al. 2005, pp. 21-22; Seronko 2004, in litt.). Trampling when 
slickspots are dry can lead to mechanical damage to the slickspot soil 
crust, potentially resulting in invasion of nonnative plants into the 
slickspots and altering the hydrologic function of slickspots, but is 
hypothesized to be less of an impact to L. papilliferum habitats than 
trampling of wet slickspot soils. Livestock trampling of water-
saturated slickspot soils that breaks through the restrictive layer 
(referred to as ``penetrating trampling'' (State of Idaho et al. 2006, 
p. 9)) has the potential to alter the soil structure and the 
functionality of slickspots (Rengasamy et al. 1984, p. 63; S