1622 Federal Register / Vol. 72, No. 8 / Friday, January 12, 2007 / Proposed Rules 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

RIN 1018–AU99 

Endangered and Threatened Wildlife 

and Plants; Withdrawal of Proposed 

Rule To List Lepidium papilliferum 

(Slickspot Peppergrass) 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Proposed rule; withdrawal. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), again 

withdraw our July 15, 2002, proposal 

(67 FR 46441) to list Lepidium 

papilliferum (slickspot peppergrass) as 

an endangered species under the 

Endangered Species Act of 1973, as 

amended (Act). The best available data 

for L. papilliferum indicates that, while 

its sagebrush-steppe matrix habitat is 

degraded, there is little evidence of 

negative impacts on the abundance of L. 

papilliferum, which inhabits slickspot 

microsites within this system. Annual 

abundance of the plant is strongly 

correlated with spring precipitation, 

therefore a high degree of variability in 

annual abundance is to be expected. 

Data on overall population trends are 

inconsistent; although recent declines 

that do not correlate with spring rainfall 

are noted in one portion of the species’ 

range, range-wide data demonstrate 

increases in abundance that continue to 

track consistently with rainfall during 

those same years. The best available 

range-wide data indicate that abundance 

of the population range-wide is strongly 

correlated with precipitation and has 

increased in recent years in association 

with increased rainfall, as expected. 

ADDRESSES: Supporting documentation 

for this action is available for public 

inspection, by appointment, during 

normal business hours at the Snake 

River Fish and Wildlife Office, 1387 S. 

Vinnell Way, Boise, ID 83709. 

FOR FURTHER INFORMATION CONTACT: 

Jeffery Foss, Field Supervisor, Snake 

River Fish and Wildlife Office at the 

above address; by telephone at 208/378– 

5243; by facsimile at 208/378–5262; or 

by electronic mail at: 

fw1srbocomment@fws.gov. 

SUPPLEMENTARY INFORMATION: 

Species Information 

Lepidium papilliferum was originally 

described as L. montanum var. 

papilliferum in 1900 by Louis 

Henderson. It was renamed L. 

papilliferum by Aven Nelson and J. 

Francis Macbride in 1913, based on its 

distinctive growth habit, short lifespan, 

and unusual pubescence (Nelson and 

Macbride 1913, p. 474). Hitchcock 

regarded L. papilliferum as L. 

montanum var. papilliferum (Hitchcock 

et al. 1964, p. 516; Hitchcock and 

Cronquist 1973). In a review of taxa in 

the mustard family (Brassicaceae), 

Rollins (1993) maintained the species 

based on differences in the physical 

features between L. papilliferum and L. 

montanum. More recently, a taxonomic 

review concluded that L. papilliferum 

warrants species recognition based on 

distinct morphological features (Lichvar 

2002), and a contrasting life history 

when compared to L. montanum 

regarding seed dormancy and its seed 

bank (Meyer et al. 2005, p. 21). The 

preliminary results of recent genetic 

studies comparing L. papilliferum with 

L. montanum indicate that L. 

papilliferum forms a monophyletic 

group or subgroup that is genetically 

distinct from L. montanum (Larson et al. 

2006, p. 13 and Figs. 4, 8; Smith 2006, 

pp. 5–7, Fig. 1). The currently accepted 

taxonomy recognizes Lepidium 

papilliferum (Henderson) A. Nels and 

J.F. Macbr as a full species (Taxonomic 

Serial No. 53383, Integrated Taxonomic 

Information System (ITIS), 2006). 

Biology 

Lepidium papilliferum is a taprooted, 

intricately branched plant. The plant 

flowers once and then dies (it is 

monocarpic), and displays two different 

life cycles, an annual and a biennial 

form. The plant averages 2 to 8 inches 

(in) (5 to 20 centimeters (cm)), but can 

reach up to 16 in (40 cm) in height. 

Leaves and stems are covered with fine, 

soft hairs, and the leaves are divided 

into linear segments. Flowers are 

numerous, 0.1 in (3 to 4 millimeter 

(mm)) diameter, white, and 4-petalled. 

Fruits (siliques) are 0.1 in (3 mm), round 

in outline, flattened, and 2-seeded 

(Moseley 1994, pp. 3 and 4; Holmgren 

et al. 2005, p. 260). 

The annual form of the Lepidium 

papilliferum matures, reproduces by 

setting seed, and dies in one growing 

season. The biennial life form initiates 

growth in the first year as a rosette, but 

does not produce seed and die until the 

second year. Biennial rosettes must 

survive dry summers on the Snake River 

Plain and Owyhee Plateau, and 

consequently many of these rosettes die 

before flowering and producing seed. 

The proportion of annuals versus 

biennials in a population can vary 

greatly (Meyer et al. 2005, p. 15). 

Depending on individual plant vigor 

and the effectiveness of pollination, 

dozens, if not thousands, of seeds can be 

produced by a single L. papilliferum 

plant (Quinney 1998, pp. 15 and 17), 

with individual biennial plants 

producing a much greater number of 

seeds than annual plants (Meyer et al. 

2005, p. 15). Average seed output for 

annual plants at the Orchard Training 

Area (OTA) (an Idaho Army National 

Guard training area on BLM land) in 

1993, was 125 seeds per plant, and in 

1994, was 46 seeds per plant. Biennial 

seed production in 1993 and 1994 

averaged 787 and 105 seeds per plant, 

respectively (Meyer et al. 2005, p. 16). 

Lepidium papilliferum seeds 

produced in a given year are dormant 

for at least a year before any germination 

takes place. Following this year of 

dormancy, approximately 6 percent of 

seeds produced in a given year 

germinate annually and approximately 3 

percent die annually (Meyer et al. 2005, 

pp. 17, 18). After 12 years, all seeds in 

a given cohort will likely have either 

died or germinated (Meyer et al. 2005, 

p. 18). Seeds are released in late June or 

early July. 

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). In an analysis of monitoring data, 

minimum and maximum temperatures 

were not statistically correlated with L. 

papilliferum abundance (Menke and 

Kaye 2006b, p. 8). 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 

apparently in many years constitutes the 

majority of the population (Mancuso 

and Moseley 1998, p. 1). According to 

Meyer et al. (2005, p. 21), ‘‘Without a 

persistent seedbank, L. papilliferum 

could probably not succeed as an 

annual in its stochastically varying 

habitat.’’ Seed banks are adaptations for 

survival in a ‘‘risky environment,’’ 

because they buffer a species from 

stochastic impacts such as lack of soil 

moisture (Baskin and Baskin 2001, p. 

160). 

Lepidium papilliferum seeds have an 

extremely patchy distribution, making it 

difficult to estimate seed density 

without taking a large number of 

samples (Meyer and Allen 2005, pp. 5, 

6). The vast majority of L. papilliferum 

seeds in slickspots (see Ecology and 

Habitat section) have been located near 

the soil surface, with lower numbers of 

seeds located in deeper soils (Meyer et 


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al. 2005, p. 19; Palazzo et al. 2005, p. 

3). L. papilliferum seeds have been 

found in slickspots with no aboveground plants (Meyer et al. in press, p. 

18; Palazzo et al. 2005, p. 10). Viable 

seeds have also been located outside of 

slickspots, indicating that some seed 

dispersal is occurring beyond slickspot 

habitat (Palazzo et al. 2005, p. 10). The 

primary seed dispersal mechanism for L. 

papilliferum has not been identified and 

is not known (Robertson and Ullappa 

2004, p. 1708). 

Lepidium papilliferum seeds located 

near the soil surface show higher rates 

of germination and viability (Meyer and 

Allen 2005, pp. 6 to 8; Palazzo et al. 

2005, p. 10), and the greatest seedling 

emergence success rate (Meyer and 

Allen 2005, pp. 6 to 8). Seeds were more 

abundant, more viable, and had greater 

germination percentages and rates from 

the upper 2 in (5 cm) of soil (Palazzo et 

al. 2005, pp. 8, 10). In another study, the 

highest level (60 percent) of seedling 

emergence was observed at a seed depth 

of 0.1 in (approximately 2 mm), with a 

marked decrease in seedling emergence 

at 0.2 in (approximately 5 mm) (Meyer 

and Allen 2005, pp. 6, 7). 

Deep burial of slickspot peppergrass 

seeds (average depths greater than 5.5 in 

(14 cm)) entombs seeds that are still 

viable and preserves them beyond the 

12-year period previously assumed as 

the maximum period of viability for 

Lepidium papilliferum seeds (Meyer 

and Allen 2005, pp. 6, 9). While there 

may be processes such as badger 

(Taxidea taxus) burrow-digging that 

could return these buried viable seeds to 

the near-surface, the successful 

establishment of seedlings may be 

reduced due to modification of soil 

layers following previous disturbance 

events (Meyer and Allen 2005, pp. 6, 8). 

The effects of environmental threats 

such as wildfire on L. papilliferum seed 

dormancy and viability are currently 

unknown. 

Lepidium papilliferum has low seed 

set in the absence of pollinators, and is 

primarily an outcrossing species 

requiring pollen from separate plants for 

more successful fruit production 

(Robertson 2003a, p. 5; Robertson and 

Klemash 2003, p. 339; Robertson and 

Ulappa 2004, p. 1707). In pollination 

experiments where researchers moved 

pollen from one plant to another, fruit 

production was observed to be higher 

with pollen from distant sources 246 to 

330 feet (ft) (75 to 100 meters (m)) away 

within a plant patch, and 4 to 12.4 miles 

(mi) (6.5 to 20 kilometers (km)) away 

from another patch of plants (Robertson 

and Ulappa 2004, p. 1705). Genetic 

exchange can occur either thorough 

pollen or seed dispersal. 

Lepidium papilliferum has been 

observed to be visited by at least 25 

families of insects, although only some 

of these insects serve as effective 

pollinators (Robertson 2003b, pp. 10, 11; 

Robertson and Klemash 2003, p. 336). 

Scarcity of pollinators were not found to 

limit seed set at any site (Robertson et 

al. 2004, p. 14). Pollinators include 

insects from several families of bees and 

ants (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). 

The pollen transfer efficiency for L. 

papilliferum varies among these insects. 

Pollinators of L. papilliferum with high 

pollen transfer efficiencies and 

visitation rates include sphecid and 

vespid wasps, bombyliid and tachnid 

flies, and honeybees, with lesser 

contributions from halictid bees. 

The genetics of Lepidium papilliferum 

were studied using samples collected 

from areas across the entire range of the 

species, including both the Snake River 

Plain and a disjunct range on the 

Owyhee Plateau (Stillman et al. 2005, 

pp. 6, 8, 9). The largest amounts of 

genetic difference occurred between the 

Snake River Plain and the Owyhee 

Plateau populations. The Snake River 

Plain and the Owyhee Plateau 

populations are separated by 44 mi (70 

km), which is considered beyond the 

distance that insect pollinators can 

travel or that seed dispersal can occur. 

Despite the distance that separates the 

Snake River Plain and the Owyhee 

Plateau populations, plants from these 

two areas share a 94-percent similarity 

in allelic diversity. This high degree of 

similarity suggests that they were either 

part of one continuous distribution or 

they originated from similar ancestral 

material (Stillman et al. 2005, pp. 6, 8, 

9). Sites in the Snake River Plain with 

fewer numbers of plants had less genetic 

diversity than sites with larger numbers 

of plants. Interestingly, a correlation 

between population size and genetic 

diversity did not exist in the Owyhee 

Plateau region. The authors suggested 

that this may be because the Owyhee 

Plateau region is less fragmented than 

the Snake River Plain, but suggested 

further genetic research is needed. 

Larson (2006, p. 14 and Fig. 4) also 

found geographically well-defined 

populations of Lepidium papilliferum 

between the Snake River Plain and 

Owyhee Plateau based on genetics. In 

contrast to the Stillman et al. (2005) 

study, Larson’s findings indicate the 

possibility of depressed genetic 

diversity in L. papilliferum based on 

significantly greater average similarity 

coefficients within collection sites of L. 

papilliferum compared to those of L. 

montanum, (Larson et al. 2006, p. 13). 

Ecology and Habitat 

The habitat of Lepidium papilliferum 

is found within semiarid sagebrushsteppe habitats in southern Idaho. This 

plant is known from the extensive 

volcanic plains of the Snake River Plain 

(and foothills) and the Owyhee Plateau, 

with most element occurrences (EOs) 

occurring on flat to gently sloping 

terrain (see Figure 1 below). Element 

occurrences are defined as ‘‘an area of 

land in which a species is or was 

present’’ (NatureServe 2002). L. 

papilliferum is associated with basalt 

ridges and plains, stable piedmont, and 

older alluvial floodplains and deposits 

(Fisher et al. 1996, pp. 14, 16). 

BILLING CODE 4310–55–C 


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BILLING CODE 4310–55–P 

Range-wide, Lepidium papilliferum is 

associated with visually distinct 

microsites known as slickspots (miniplayas or natric sites) (Moseley 1994, p. 

7). Slickspots are distinguished from the 

surrounding sagebrush matrix as having 

the following characteristics—

microsites where water pools when rain 

falls (Fisher et al. 1996, pp. 2, 4); little 

vegetation; more distinct soil layers 

with a more columnar or prismatic 

structure; higher alkalinity and clay 

content and natric (higher sodium) 

properties (Fisher et al. 1996, pp. 15, 16; 

Meyer and Allen 2005, pp. 3 to 5, 8); 

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). The 

slickspots range in size from less than 

10 square feet (ft 2) (1 square meter (m 2)) 

to about 110 ft 2 (10 m 2) (Mancuso et al. 

1998, p. 1), but most are between 10 ft 2

and 20 ft 2 (1 m 2 and 2 m 2). 

Slickspots cover a relatively small 

cumulative area within the larger 

sagebrush-steppe matrix, and only a 

small percentage of slickspots are 

known to be occupied by Lepidium 

papilliferum. For example, a thorough 

field inventory within the Juniper Butte 

Range in 2002 found that of the 11,070 


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acres (ac) (4,480 hectares (ha)) surveyed, 

approximately 1 percent (109 ac (44 ha)) 

consisted of slickspot habitat, and only 

4 percent of the slickspot habitat was 

occupied by above-ground L. 

papilliferum plants (U.S. Air Force 

2002, p. 9). The total amount of 

occupied slickspot habitat (aboveground plants and known occurrences 

of seed in the soil) within this large 

occurrence was approximately 4 ac (1.6 

ha) at the time it was surveyed (0.1 

percent of the acreage). 

Based on studies in 2004 on the 

Orchard Training Area (OTA), a training 

area of the Idaho Army Reserve National 

Guard (IARNG) on the Snake River 

Plain, slickspots have three primary 

layers: the surface silt layer, the 

restrictive layer, and the moist clay 

layer beneath. The top two layers 

(surface silt and restrictive) of slickspots 

are very thin; the surface silt layer varies 

in thickness from 0.1 to 1.2 in (a few 

mm to 3 cm) in slickspots known to 

support Lepidium papilliferum, and the 

restrictive layer varies in thickness from 

0.4 to 1.2 in (1 to 3 cm) (Meyer and 

Allen 2005, p. 3). The moist clay basal 

layer, which continues down to 

bedrock, is consistently below the 

restrictive layer (Meyer and Allen 2005, 

p. 3). All slickspots have variations in 

surface silt thickness. 

As part of the Lepidium papilliferum 

Habitat Integrity and Population (HIP) 

monitoring conducted range-wide in 

2005, the depth of the surface silt layer 

was measured 3 times in every slickspot 

along 79 transects across the range of L. 

papilliferum; a total of 769 slickspots 

were sampled. Measurements were 

taken directly adjacent to live L. 

papilliferum plants; the range-wide 

mean surface silt layer depth was 0.31 

in (0.78 cm) (Colket 2006a). 

The surrounding sagebrush matrix 

soils are distinguished from slickspot 

soils by a deeper silt layer with a clay 

layer beneath, and usually the 

restrictive layer is lacking (Meyer and 

Allen 2005, pp. 3 to 5). Non-slickspot 

soils at the OTA had thick silt layers 

with a mean depth of 4.7 in (12 cm); the 

silt layer typically transitioned directly 

into the clay layer beneath, although 

some samples had restrictive layers 

which were abnormally thickened (over 

3.9 in (10 cm)) (Meyer and Allen 2005, 

pp. 3 to 5, 8). 

It is unknown how long slickspots 

take to form, but it is hypothesized to 

take several thousands of years 

(Nettleton and Petersen 1983, p. 193; 

Seronko 2006, p. 1). The conditions that 

allowed for the formation of slickspots 

in southwestern Idaho are thought to 

have occurred during a wetter 

Pleistocene climate. Holocene additions 

of wind-carried salts (often loess 

deposits) produced soils high in sodium 

(natric) (Nettleton and Petersen 1983, p. 

191; Seronko 2006, p. 1). It may take 

several hundred years to alter or lose 

slickspots through natural climate 

change or severe natural erosion 

(Seronko 2006, p. 1). Some researchers 

hypothesize that, given current climatic 

conditions, new slickspots are no longer 

being created (Nettleton and Petersen 

1983, pp. 166, 191, 206), but that some 

slickspots subjected to light disturbance 

in the past may re-form (Seronko 2006, 

p. 1). Slickspots may be destroyed and 

lost to disturbances that alter the 

physical properties of the soil layers. 

The forces that hold clay particles 

together are greatly weakened when 

sodium-clay and water come into 

contact. In this condition, clay particles 

are easily detached or dispersed from 

larger aggregates, i.e., slickspot soils are 

especially susceptible to mechanical 

disturbances when wet (Rengasmy et al. 

1984, p. 63; Seronko 2004, pp. 1, 2). 

Such disturbances disrupt the soil 

layers important to Lepidium 

papilliferum’s seed germination and 

seedling growth. Meyer and Allen 

(2005, p. 9) suggest that if sufficient 

time passes following the disturbance of 

slickspot soil layers, it is possible that 

the slickspot soil layers may reform 

similar to their pre-disturbance 

configuration. Slickspots that no longer 

support L. papilliferum, but still retain 

the thin silt and restrictive layer 

structure, are the most likely sites to 

support reintroductions. Restoration 

and species reintroduction potential for 

L. papilliferum habitat have not been 

studied. 

The highest monthly temperatures 

within the range of Lepidium 

papilliferum normally occur in July 

(approximately in the low 90 degrees 

Fahrenheit (approximately 33 degrees 

Celsius)), and lowest monthly 

temperatures occur in January 

(approximately in the low 20 degrees 

Fahrenheit (minus 7 degrees Celsius)). 

Average precipitation within the 

species’ range is 11.7 in (29.7 cm) for 

Boise, 7.4 in (18.8 cm) for Bruneau, and 

9.9 in (25.1 cm) for Mountain Home. 

Precipitation tends to fall as rain, 

primarily in winter and spring 

(November to May); the lowest rainfall 

occurs in July and August, and June, 

September, and October receive slightly 

more. Freeze-free days average about 

120 days in Boise, 146 days in Bruneau, 

and 138 days in Mountain Home (WRCC 

2006). 

Spring precipitation has been 

correlated with above-ground numbers 

of Lepidium papilliferum in several 

analyses. Palazzo et al. (2005, p. 9) and 

Menke and Kaye (2006a, p. 8) utilized 

Habitat Integrity Index (HII) range-wide 

data collected from 1998 to 2001. Menke 

and Kaye (2006b, pp. 10, 11) utilized HII 

data collected from 1998 to 2002, as 

well as 2004 Habitat Integrity and 

Population (HIP) data. Meyer et al. 

(2005, p. 15) utilized demographic data 

from the OTA collected from 1993 to 

1995. Palazzo et al. (2005, p. 9) found 

a positive relationship (p-value of less 

than 0.01) between above-ground plants 

and February to June precipitation. 

Menke and Kaye (2006a, p. 8) found 

March to May precipitation accounted 

for 99.4 percent (2006a, p. 8) and 89 

percent (2006b, pp. 10, 11) of the 

variation in L. papilliferum numbers. 

Meyer et al. (2005, p. 15) found that an 

increase in February through May 

precipitation increased the number of L. 

papilliferum seedlings at the OTA. This 

correlation of abundance with spring 

rainfall is important, as it at least 

partially explains past fluctuations in 

population numbers, and suggests that 

perceived declines were largely a result 

of years with low precipitation levels. 

Menke and Kaye (2006b, p. 8) also 

found that minimum and maximum 

temperatures were not statistically 

correlated with L. papilliferum 

abundance. 

The sparse native vegetation naturally 

present at slickspots suggests that 

Lepidium papilliferum is more tolerant 

than surrounding vegetation at 

surviving in alkaline soils and spring 

inundation. Plant ecology literature 

suggests that plants tolerant of stress 

(e.g., alkaline soils) are poor competitors 

(Grime 1977, p. 1185). 

Range and Distribution 

Lepidium papilliferum is known only 

from the Snake River Plain and its 

adjacent northern foothills (an area 90 

by 25 mi (145 by 40 km)) in southwest 

Idaho, and a disjunct population on the 

Owyhee Plateau in Idaho (see Figure 1 

above). The plant occurs at elevations 

ranging from approximately 2,200 ft 

(670 m) to 5,400 ft (1,645 m) in Ada, 

Canyon, Gem, Elmore, Payette, and 

Owyhee Counties (Moseley 1994, pp. 3 

to 9). The separation of population 

centers into two physiographic regions 

is important for the conservation of L. 

papilliferum. We regard the two 

physiographic regions as two distinct 

metapopulations, the Snake River Plain 

metapopulation and the Owyhee 

Plateau metapopulation. 

Metapopulation concepts are useful 

when considering fragmented habitats, 

such as those within L. papilliferum’s 

range, because they include discussion 

of when extinction events exceed 

colonization events, which can cause 


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the species to not persist (Husband and 

Barrett 1996, pp. 461 to 462). 

In 2003, a ‘‘Candidate Conservation 

Agreement for Slickspot Peppergrass 

(Lepidium papilliferum)’’ (CCA) was 

developed by several State, Federal, and 

private entities in Idaho (State of Idaho 

et al. 2003) (see Previous Federal 

Actions section). The CCA is based on 

two geographical management areas that 

include known EOs, one on the Snake 

River Plain and a second on the Owyhee 

Plateau, called ‘‘consideration zones.’’

Although somewhat arbitrary in nature, 

this designation is useful for 

management purposes. There are 

1,595,205 ac (645,597 ha) within the 

Snake River Plain consideration zone, 

and 126,946 ac (51,373 ha) within the 

Owyhee Plateau consideration zone. 

Factors affecting the species vary 

between the two physiographic regions. 

For example, urban and rural 

development, agriculture, and 

infrastructure development of 

sagebrush-steppe habitat has been 

substantial within the Snake River 

Plain, but little development has 

occurred within the Owyhee Plateau 

portion of L. papilliferum’s range. 

Element occurrences have been used 

to describe distribution of Lepidium 

papilliferum by assuming that slickspots 

within 1 kilometer (0.6 mi) of each other 

are capable of genetic exchange through 

pollination (Colket and Robertson, pers. 

comm. 2006). As of February 2006, there 

were 85 delineated EOs that occupied 

13,359 ac (5,406 ha) (Colket et al. 2006). 

We estimate that the actual acreage 

occupied by L. papilliferum is only a 

fraction of a percent of this total acreage 

number because the majority of 

slickspots are not occupied by L. 

papilliferum and slickspots occupy a 

small percentage of the landscape (see 

U.S. Air Force 2002, p. 9, for an 

example). Of these EOs, 60 (11,025.3 ac 

(4,461.8 ha)) occur on the Snake River 

Plain, and 25 (2,333.8 ac (944.5 ha)) 

occur on the Owyhee Plateau (Colket et 

al. 2006, Table 14). Of the total EO 

acreage, 521 ac (211 ha) (3.9 percent) 

occur on private lands, 1,254 ac (507 ha) 

(9.4 percent) occur on lands managed by 

the State of Idaho, and 11,582 ac (4,687 

ha) (86.7 percent) occur on Federal 

lands (USFWS 2006c). On the Snake 

River Plain, 85 percent of the EO 

acreage occurs on federally managed 

lands, 10.3 percent of the EO acreage 

occurs on State-managed lands, and 4.7 

percent of the EO acreage occurs on 

private lands. On the Owyhee Plateau, 

94.7 percent of the EO acreage occurs on 

Federally managed lands, with the 

remaining 5.3 percent occurring on 

State managed lands; no EOs on the 

Owyhee Plateau occur on private lands. 

The approximate extant range of the 

plant was first described in 1994 

(Moseley 1994, p. 6), and has not 

changed substantially since, although 

the amount of known occupied habitat, 

particularly on the Owyhee Plateau, has 

expanded in recent years. Since 2003, 

sixteen new occurrences, all within 3 mi 

(4.8 km) of previously existing 

occurrences, have been documented: 2 

on the Snake River Plain with an area 

of 2.7 ac (1 ha) and approximately 2,500 

individuals, and 14 on the Owyhee 

Plateau with an area of 46.6 ac (18 ha) 

and approximately 650 individuals 

(Colket et al. 2006, Tables and 

Appendix A). It should be noted that 

not all potential L. papilliferum habitat 

in southwest Idaho has been surveyed, 

and it is likely that additional occupied 

L. papilliferum sites will be found. 

Estimating the number of individuals 

(abundance) of Lepidium papilliferum is 

confounded by its annual or biennial 

life cycle, because the number of 

individuals of each life form can 

fluctuate widely depending on 

precipitation. To assess abundance, we 

utilized four available data sets: rangewide EO records maintained by the 

Idaho Conservation Data Center (CDC), 

range-wide data associated with the HII/ 

HIP monitoring, transect monitoring 

data collected on the OTA, and special 

use plot data from the OTA. 

As of February 2006, the Idaho CDC 

had ranked 101 EO records for Lepidium 

papilliferum (Colket et al. 2006a, pp. 15 

to 41); 9 are ranked as extirpated (lost) 

or probably extirpated, and 7 are 

considered historical (information for 

most is too vague for relocation). All 9 

extirpations were verified locations 

from old herbarium collections, the 

most recent from 1955, where the 

habitat has been completely converted 

to urban or agricultural lands (Colket et 

al. 2006, Table 13). The remaining 85 

records (as of February 2006) are for EOs 

considered extant (existing). In the 

review of EO specifications and ranks 

conducted in February 2006, observed 

abundance was categorized as being 

greater than 1,000 plants, 400 to 999 

plants, 50 to 399 plants, less than 50 

plants, 0 plants, or an unknown number 

of plants. This classification was based 

on the number of plants present at the 

last survey, regardless of year and 

associated precipitation patterns. 

Existing data provide an estimated 

abundance for extant EOs: 15 (18 

percent) have over 1,000 plants, 11 (13 

percent) have between 400 and 999 

plants, 1 (1 percent) has about 400 

plants, 18 (21 percent) have between 50 

and 399 plants, 22 (26 percent) have 

fewer than 50 plants, 9 (11 percent) had 

no plants at the last visit, and 9 (11 

percent) have an unknown number of 

individuals. 

Two monitoring methods, HII and 

HIP, have been used range-wide for 

Lepidium papilliferum. Each included 

different methodologies, but are still 

useful for tracking abundance at 

transects across the two efforts. HII 

monitoring was developed to assess the 

overall habitat condition that includes 

attributes associated with the slickspots 

and the sagebrush-steppe habitat, 

occurred for 4 years (1998 to 2001), and 

is presented in various reports 

(Mancuso and Moseley 1998; Mancuso 

et al. 1998; Mancuso 2000, 2001, 2002; 

Menke and Kaye 2006a, b). HIP 

monitoring was developed to assess the 

overall habitat condition that includes 

those attributes associated with the 

slickspots and the sagebrush-steppe 

habitat, and also the effectiveness of the 

CCA. HIP monitoring was conducted in 

2004 and 2005 (State of Idaho et al. 

2006, p. 18), and is expected to 

continue. HIP monitoring results in 

2004 are reported in Menke and Kaye 

2006b, and results through 2005 are 

included in our report ‘‘Best Available 

Biological Information for Slickspot 

Peppergrass (Lepidium papilliferum)’’

(USFWS 2006f, Figures 8, 9). Although 

neither the HII nor HIP methodologies 

have been peer reviewed, they represent 

the best available survey and monitoring 

techniques for L. papilliferum. 

Abundance data for Lepidium 

papilliferum have been collected rangewide since 1998, and collected at the 

OTA since the early 1990s. The rangewide HII and HIP transect data illustrate 

that plant abundance is positively 

correlated with spring precipitation, and 

specifically that rainfall in the months 

of March through May accounts for 89 

percent of the variability in plant 

numbers (Menke and Kaye 2006b, p. 

10). Plant abundance therefore 

fluctuates widely between years in 

association with precipitation. In the 

areas monitored by HII and HIP, Menke 

and Kaye (2006b, p. 10) report that L. 

papilliferum abundance decreased 

range-wide between 1998 and 1999, 

remained low through 2002, and began 

to increase again beginning in 2002. 

This pattern closely tracks that of 

rainfall during those same years. 

Abundance data from transects at the 

OTA illustrate declines in abundance 

first noted in 1996, with a declining 

trend in recent years that is not 

correlated with spring precipitation 

(Weaver 2006, pp. 1–6). Abundance data 

from the range-wide HII and HIP 

transects showed increasing trends in L. 

papilliferum between the years 2002 

and 2005 (no data were collected in 

2003) (USFWS 2006f, Figures 8, 9). 


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Thus range-wide abundance data from 

the HII and HIP transects continue to 

show a consistently positive correlation 

with spring precipitation. We consider 

this range-wide data to be the best 

available at this time. 

We conducted a review of the 

abundance data and study methodology 

following the reopened comment period 

on the proposal to list L. papilliferum as 

endangered (October 23, 2006, to 

November 13, 2006; 71 FR 62078). A 

review of the special use plot counts at 

the OTA (USFWS 2006e, Figure 7) 

shows a decline in plant numbers 

during the drought years of 1992 (249 

plants), 1997 (624 plants), and 2002 

(270 plants) followed by a positive 

response in plant numbers as spring 

precipitation increased in subsequent 

years 1993 (6,369 plants), 1998 (3,330 

plants), and 2003 (4,080 plants). 

Reviewing the special use plot data at 

OTA for 2004–2006 illustrates a 

relatively stable or declining number of 

plants despite increases in spring 

precipitation. 

We reviewed the OTA population 

monitoring transect study and updated 

the description of the study methods 

from our BAI based upon clarification of 

new information provided by IARNG 

staff during the reopened comment 

period on the proposal to list L. 

papilliferum as endangered (October 23, 

2006, to November 13, 2006; 71 FR 

62078). The BAI cited study methods as 

described by IARNG staff and stated that 

the census effort occurred annually at 

the OTA and that observers cover 98 

percent of the plants’ habitat at OTA. 

New information obtained since the BAI 

was written suggests that 90 percent 

may be a more accurate estimate of the 

amount of habitat surveyed at OTA. 

Since 2003, additional plant inventories 

have increased the size of the known 

population of L. papilliferum at OTA, 

including the documentation of 365 

new occupied slickspots in 2005 (URS 

Corporation 2005, pp. 6–7). The OTA 

population monitoring transects for 

2005 reported 18,599 plants in the 

transect areas; the survey inventory by 

URS corporation reported 43,925 plants 

(365 new slickspots with L. 

papilliferum, 125 historic slickspots 

with L. papilliferum, 66 historic 

slickspots without L. papilliferum) in 

the areas surveyed at OTA (URS 

Corporation 2005, p. 7). 

We reviewed the results of range-wide 

HII and HIP monitoring, including 

reported plant abundance since these 

studies were initiated in 1998, and new 

information available to us since the 

time we last issued a listing finding on 

this species. These data illustrate a 

general pattern of plant numbers 

correlating with spring precipitation 

(USFWS 2006f, Figures 8, 9). Data are 

incomplete for 2002 and 2003. Menke 

and Kaye (2006b, p. 19) report that 

‘‘populations generally decreased 

during 1998–2004 and these trends 

appear to be strongly influenced by 

spring precipitation.’’ In contrast to the 

results reported from the OTA, rangewide abundance of Lepidium 

papilliferum as measured by the HII and 

HIP increased as spring precipitation 

increased in the years 2002 through 

2005 (USFWS 2006f, Figures 8, 9). 

Comparing years 1998 and 2005, which 

are relatively comparable in terms of 

range-wide spring precipitation (6.6 

inches and 6.3 inches, respectively), 

plant numbers are also similar (17,611 

and 15,226 respectively), indicating 

little change in overall abundance of L. 

papilliferum range-wide over this time 

interval, despite the intervening 

fluctuations in yearly abundance that 

are to be expected for an ephemeral 

annual plant. In general, the HII and HIP 

data from 1998–2005 indicate that the 

abundance of L. papilliferum rangewide remained relatively stable over 

this time interval (USFWS 2006f, Figure 

8). We consider this range-wide data to 

be the best available at this time. 

Habitat Quality 

Vegetation community data are 

collected as one component of Lepidium 

papilliferum HIP monitoring. One of the 

attributes documented in HIP 

monitoring is the fire history pattern. 

Observations are recorded to document 

if there is evidence of fires at four 

landscape scales; in the HIP transects, 

and in the surrounding habitat at 65 

meters, 250 meters, and 500 meters from 

the transect. Given the mosaic pattern of 

wildfire burns, often the surrounding 

habitat may be burned while an 

individual HIP transect is unburned or 

predominately unburned. In 2004, 

vegetation communities were sampled 

at 71 HIP transects, and 41 (58 percent) 

of the transects were classified as 

unburned, with predominantly big 

sagebrush cover and less than 33 

percent introduced annual cover; 7 (10 

percent) were classified as unburned, 

with moderate big sagebrush cover and 

at least 33 percent introduced annual 

cover; 6 (8 percent) were classified as 

burned, with predominantly native 

vegetation, although introduced annual 

cover sometimes comprised up to 50 

percent of the total plant cover; 2 (3 

percent) were classified as burned, with 

predominantly introduced annual cover 

(Salsola kali (Russian thistle or 

tumbleweed) and Ceratocephala 

testiculata (bur buttercup, formerly 

Ranunculus testiculatus)), with low 

cheatgrass (Bromus tectorum) and some 

crested wheatgrass (Agropyron 

cristatum); 11 (14 percent) were 

classified as burned and dominated by 

cheatgrass; and 4 (6 percent) were 

classified as burned and seeded with 

crested wheatgrass (Colket 2005a, p. 8). 

In summary, over 42 percent of the HIP 

vegetation plots along HIP transects 

were in habitats with over 33 percent 

nonnative, invasive plant cover. 

Menke and Kaye (2006b) evaluated 

the association between measures of 

habitat quality measured by HIP and 

abundance of L. papilliferum. For the 

one year for which data were available 

(2004), they report that L. papilliferum 

abundance was not significantly 

correlated with soil crust cover or 

weedy species cover in slickspots, and 

that the proportion of flowering plants 

had a positive correlation with soil crust 

cover, but was not significantly 

correlated with livestock print cover or 

weedy species cover (Menke and Kaye 

2006b, p. 15). In their overall evaluation 

of habitat condition, they report that 

total vascular plant cover, species 

richness, and species diversity had 

declined between 1998 and 2004, and 

suggest that past fires have been a factor 

in degrading slickspot condition (Menke 

and Kaye 2006b, p. 19). Several features 

of slickspots, including soil crust cover 

and weedy species cover, were 

consistently more degraded in burned 

areas. Although slickspots in burned 

areas had more dense weedy annual 

species cover (Menke and Kaye 2006b, 

p. 19), Menke and Kaye state that 

‘‘Competition from weedy annual 

species (which may be promoted by 

fire), does not appear to influence 

abundance of L. papilliferum plants in 

a given year, but may influence 

reproductive output, other plant traits, 

and other life history stages’ (Menke and 

Kaye 2006b, p. 17). Soil crust cover was 

significantly lower in 2004 transects 

with evidence of livestock grazing, but 

there was no direct relationship 

between abundance of L. papilliferum 

and total livestock print cover or cover 

of print penetrating to the slickspot clay 

layer (Menke and Kaye 2006b, p. 15). 

Another measure of habitat quality 

within Lepidium papilliferum’s range is 

the EO ranking by the Idaho CDC. The 

first EO ranks for L. papilliferum were 

assigned in 1993 (Colket et al. 2006, 

Tables 1–13). In 2006, EO specifications 

and ranking were revised by the Idaho 

CDC (Colket et al. 2006, pp. 15 to 44). 

Due to the change in methodology, it is 

difficult to draw conclusions about 

changes in EO rankings over time. EO 

ranks are designed as an assessment of 

estimated viability or probability of 

persistence and help prioritize 


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conservation planning or actions 

(NatureServe 2002, p. 36). We consider 

EO rankings to be part of the best 

available data on the species at this 

time. 

Table 1 summarizes the rankings for 

85 EOs based on the 2006 revised 

methodology. A-ranked EOs have one or 

more of the following conditions that 

are summarized through a formula: (1) 

Over 1,000 detectable above-ground 

plants; (2) intact native plant 

communities with trace nonnative 

species cover; (3) slickspots with zero or 

trace nonnative cover or livestock 

disturbance; (4) zero or few minor 

anthropogenic disturbances; (5) a lack of 

burning; and (6) a surrounding 

landscape within 0.6 mi (1 km) that is 

not fragmented by agricultural lands, 

residential or commercial development, 

introduced annual grasslands, or drill 

seeding projects (Colket et al. 2006, p. 

3). By contrast, D-ranked EOs exist in 

the most highly degraded habitats, with 

the fewest plants, and with the most 

degraded surrounding landscape (Colket 

et al. 2006, p. 3). 

TABLE 1.—NUMBER OF ELEMENT OCCURRENCES IN 2006 BY CDC RANKING (PERCENT OF TOTAL) 

[Colket et al. 2006, Tables 1 to 13 and Appendix C] 

A B BC C pC 1 D pD 1 E2 F Total 

0 ................................. 15 (18) 1 (1) 26 (31) 4 (5) 19 (22) 1 (1) 10 (12) 9 (11) 85 

1Probable ranks assigned when incomplete information available. 

2 Not enough habitat information available to make a ranking. 

Of the 66 EOs with B through D 

rankings (13,123 ac (5,310 ha)), 51 occur 

on the Snake River Plain (10,804 ac 

(4,372 ha)), and 15 on the Owyhee 

Plateau (2,318 ac (938 ha)). Of these 66 

middle-ranked EOs, 50 are ranked as a 

C or D (averaging fewer than 399 plants, 

partial to nonexistent native plant 

communities that are partially to 

predominately burned, and partially to 

predominantly fragmented landscapes). 

The 40 EOs on the Snake River Plain 

cover 3,170 ac (1,283 ha), and the 10 

EOs on the Owyhee Plateau cover 73 ac 

(30 ha). 

Habitat data (HII, HIP) have been 

collected annually for approximately 

one-half of the extant EOs since 1998. 

Given that monitoring methodologies 

and the specifications for determining 

EO rank changed in 2004/2005, and not 

every EO is monitored annually, it is not 

possible to draw definitive conclusions 

about the change in habitat quality over 

time. It is possible, however, to gain an 

understanding of the current condition 

of habitat quality from the available 

data. Based on the most recent EO 

ranks, at least 75 percent (n = 49) were 

ranked as C, D, or F, indicating that 

most EOs occurred in partially or 

predominantly fragmented landscapes 

with partial to nonexistent native plant 

communities. As discussed below we 

don’t have any data that correlate L. 

papilliferum population numbers with 

effects to habitat. 

Previous Federal Actions 

For a description of Federal actions 

concerning Lepidium papilliferum that 

occurred prior to January 22, 2004, 

please refer to the document to 

withdraw our July 15, 2002, proposal 

published in the Federal Register on 

January 22, 2004 (69 FR 3094). 

On January 22, 2004, we published a 

document withdrawing our proposed 

rule to list Lepidium papilliferum as 

endangered (69 FR 3094). That action 

was based on our conclusion that there 

was ‘‘a lack of strong evidence of a 

negative population trend, and the 

formalized conservation plans (e.g., the 

CCA and INRMPs) had sufficient 

certainty that they would be 

implemented and effective such that the 

risk to the species was reduced to a 

level below the statutory definition of 

endangered or threatened.’’

On April 5, 2004, Western Watersheds 

Project filed a lawsuit challenging our 

decision to withdraw the proposed rule 

to list Lepidium papilliferum as 

threatened or endangered (Western 

Watersheds Project v. Jeffery Foss, et al., 

Case No. CV 04–168–S–EJL). On August 

19, 2005, the U.S. District Court for the 

District of Idaho reversed the decision to 

withdraw the proposed rule, with 

directions that the case be remanded to 

the Secretary of the Department of 

Interior for reconsideration of ‘‘whether 

a proposed rule listing the slickspot 

peppergrass as either threatened or 

endangered should be adopted.’’

After issuance of the District Court’s 

remand order, we notified Federal, State 

and local agencies, county governments, 

elected officials, and other interested 

parties of the Court’s decision in a letter 

dated October 13, 2005. We requested 

new scientific data and comments about 

Lepidium papilliferum. We also stated 

that scientific data received from the 

public would be included in an updated 

‘‘Draft Best Available Biological 

Information for Slickspot Peppergrass 

(Lepidium papilliferum)’’ (BAI) 

document. In response to our request, 

we received a total of 13 comment 

letters. The updated BAI combined all 

existing and new information about the 

species and its habitat, and we utilized 

it in making this final listing 

determination. 

On February 27, 2006, we opened a 

30-day public comment and peer review 

period, through an electronic process 

referred to as VOCUS, for our 

comprehensive document entitled 

‘‘Draft Best Available Biological 

Information for Slickspot Peppergrass 

(Lepidium papilliferum)’’ (USFWS 

2006f). Following public and peer 

review, we used new data and technical 

corrections, along with existing data, for 

our analysis described below as the best 

available scientific and commercial 

data. 

After an order by the district Court on 

October 4, 2006, which requires ‘‘a final 

listing determination on the slickspot 

peppergrass by January 4, 2007,’’ we 

opened a 22-day public comment period 

that closed on November 13, 2006 (71 

FR 62078). A variety of documents were 

posted on the FWS Web site for public 

comment, including peer review 

comments on the draft BAI and results 

of the expert panel. 

Summary of Comments and Responses 

We received a total of 13 comment 

letters in response to our October 13, 

2005, request for additional information 

to assist with the listing determination 

for Lepidium papilliferum; 17 public 

comment letters and 19 peer review 

responses on the Draft BAI released on 

February 27, 2006; and 20 public 

comment letters in response to our 

October 23, 2006, reopening of the 

public comment period. The majority of 

comments were specific to the draft BAI 

and associated data as well as issues 

surrounding the 2003 CCA developed to 

conserve L. papilliferum. Comments 

that were substantive or that provided 

new information were incorporated into 

the final determination where 

appropriate, or are addressed below. We 

consolidated the comments into 

categories by issue. 


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Issue 1: Several commenters provided 

new data and information regarding the 

biology, ecology, life history, genetics, 

and factors affecting Lepidium 

papilliferum, and requested that it be 

incorporated into the body of existing 

knowledge concerning the species and 

considered by us in making any future 

management determinations. 

Our response: In making this final 

listing determination, we have 

considered scientific and commercial 

data contained in over 75 technical 

reports, published journal articles, and 

other general literature documents, 

including nearly 30 reports received 

since the January 23, 2004. The body of 

available information specific to this 

species has greatly expanded since 

2004, with new information regarding 

species locations, known condition of 

its habitat, slickspot soil characteristics 

and disturbance, Lepidium 

papilliferum’s pollinators, seed viability 

and germination, ongoing conservation 

efforts, genetics, and factors affecting 

the species. This information was 

contained in various State agency 

reports (Colket 2005a; Colket 2006; 

Colket et al. 2006; IDARNG 2005; State 

of Idaho et al. 2006) and other scientific 

reports and peer reviewed articles 

(Menke and Kaye 2006a, b; Meyer and 

Allen 2005; Meyer et al. 2005; Meyer et 

al. 2006; Palazzo et al. 2005; Robertson 

2003a; Robertson and Klemesh 2003; 

Robertson and Ulappa 2004; Robertson 

et al. 2005; Stillman et al. 2005). 

Additionally, we reviewed and 

considered data from ongoing L. 

papilliferum conservation efforts 

(Binder 2006; Boise Airport 2003; 

Hoffman 2005; IDARNG 2005; State of 

Idaho et al. 2006; U.S. Air Force 2004). 

Further research and continued 

monitoring would provide a more 

thorough understanding of the species; 

however, we have a legal obligation to 

make a final listing determination based 

on the best available scientific and 

commercial data. 

Issue 2: Some commenters stated that 

an urgent need to list Lepidium 

papilliferum exists due to ongoing and 

current threats. One commenter 

suggested that there is evidence for 

widespread and rapid population 

decline. Another commenter stated that 

the species is at such risk of extinction 

that it should be listed to ensure that the 

BLM and other Federal land 

management agencies implement 

management actions that result in 

substantive conservation. Other 

commenters stated that existing 

regulations are insufficient in providing 

for the long-term persistence of the 

species. Conversely, some commenters 

stated that existing regulatory 

mechanisms, primarily through the CCA 

and its associated conservation 

measures, are sufficient or more than 

sufficient to preclude the need to list L. 

papilliferum under the Act. 

Our response: The Act requires us to 

make listing decisions based solely on 

the best scientific and commercial data 

available at the time the decision is 

made (section 4(b)(1)(A) of the Act). We 

thoroughly reviewed all available 

scientific and commercial data for 

Lepidium papilliferum in preparing this 

final determination. We reviewed 

historical and recent publications, and 

unpublished reports concerning L. 

papilliferum and the sagebrush-steppe 

habitat of southwestern Idaho. From this 

information, we produced the document 

‘‘Draft Best Available Biological 

Information for Slickspot Peppergrass 

(Lepidium papilliferum)’’ (BAI); we 

solicited public comment and peer 

review on the BAI in February 2006. We 

also convened a panel of seven 

scientific experts to review the scientific 

information available to us pertaining to 

L. papilliferum. Additionally, we 

reopened the public comment period on 

the proposed rule in October 2006 (71 

FR 62078) to solicit additional review 

and comment on new data that we have 

considered in this final determination. 

We followed our Policy on 

Information Standards Under the 

Endangered Species Act, published in 

the Federal Register on July 1, 1994 (59 

FR 34272), and our associated 

Information Quality Guidelines in 

preparing this final determination. Our 

evaluation of the significance of these 

numerous ongoing threats across the 

range of Lepidium papilliferum is 

presented in the Summary of Factors 

Affecting the Species section of this 

final determination. This analysis 

includes the adequacy of existing 

regulatory mechanisms, including 

public land management practices. 

During the listing process, we provided 

6 public comment periods that were 

open for a total of 262 days, and held 

2 public hearings. We received new 

information since the proposed rule 

specific to L. papilliferum that ranged 

from additional Idaho CDC survey data 

to slickspot soils information. While the 

body of available information specific to 

this species is limited, our legal 

obligation is to make a final listing 

determination based on the best 

available data. 

Issue 3: Several comments regarded 

the effectiveness of the CCA (first 

approved in 2003 and subsequently 

revised in 2006) in conserving Lepidium 

papilliferum. Some commenters stated 

that the voluntary commitment of nongovernmental cooperators developed 

during the CCA process is equal to or 

better for conservation of L. papilliferum 

than mandated actions that would be 

associated with listing the species. One 

commenter suggested that the 

commitment to better livestock grazing 

management by the L. papilliferum 

Conservation Committee and permittees 

continues, and is still strong after 2 

years of implementation, and that the 

follow-through on implementing CCA 

conservation measures, such as 

responding to grazing triggers and offhighway vehicle (OHV) events during 

2005, was good. The State of Idaho 

reported that, of the 203 conservation 

measures identified in the CCA, 193 

were accomplished in either 2004 or 

2005, and 7 measures were not 

implemented due to wildfire or ongoing 

litigation. One commenter stated that 

the inclusion of an adaptive 

management process within the CCA 

will ensure that the identified 

conservation measures, if initially 

ineffective, would become effective well 

before the probable extinction of L. 

papilliferum given existing threats. The 

U.S. Air Force provided comments on 

our October 23, 2006 draft description 

and analysis of conservation measures 

(71 FR 62078). The U.S. Air Force 

believed that several more conservation 

measures have been implemented and 

are effective in conserving L. 

papilliferum at the Juniper Butte Range 

than what we had determined. 

Conversely, some comments 

suggested that there is little certainty 

that implementation of Lepidium 

papilliferum conservation measures 

identified in the CCA will occur. One 

commenter stated that the adaptive 

management approach used in the CCA 

provides no certainty of protection for L. 

papilliferum. Another commenter 

suggested that any cooperator can drop 

out of the CCA at any time without 

repercussion. Another comment 

asserted that the adaptive management 

approach as currently described in the 

CCA allows for a one-time disturbance 

event that could result in irreversible 

harm to L. papilliferum habitat. 

Comments indicated that the CCA 

provides vast opportunity for a one-time 

livestock penetrating trampling event to 

occur, and is therefore insufficient. 

Other comments suggested that the CCA 

does not protect L. papilliferum and its 

habitat from soil disturbance, and did 

not include active restoration measures 

for the vast majority of the species’

habitats. Commenters stated that, due to 

the downward trend in L. papilliferum 

abundance, reintroduction of the 

species should be considered. One 

commenter stated that management 


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1630 Federal Register / Vol. 72, No. 8 / Friday, January 12, 2007 / Proposed Rules 

under an Instruction Memorandum (IM) 

is uncertain, and that because the IM is 

not a legal requirement, interpretation 

will be inconsistent among field staff. 

Our response: We support utilizing a 

collaborative conservation approach to 

address factors affecting species being 

considered for listing under the Act. 

Prior to July 18, 2003, we worked with 

various agencies and individuals to 

assess the status of Lepidium 

papilliferum, and also to identify and 

implement conservation actions. Since 

February 2000, we have been an active 

technical advisor in an interagency 

group of biologists and stakeholders to 

share data and coordinate conservation 

actions for L. papilliferum. 

Using our Policy for Evaluation of 

Conservation Efforts When Making 

Listing Decisions (PECE) (68 FR 15100), 

we reviewed the conservation measures 

in five plans, or conservation strategies, 

for L. papilliferum: (1) The Candidate 

Conservation Agreement for Slickspot 

Peppergrass (CCA), which was initially 

approved in 2003 and revised in 2006; 

(2) the Idaho Army National Guard 

Integrated Natural Resource 

Management Plan for Gowen Field/ 

Orchard Training Area; (3) the U.S. Air 

Force Integrated Natural Resource 

Management Plan for Mountain Home 

Air Force Base, which was modified in 

2004 and contains more measures that 

promote the conservation of L. 

papilliferum than the 2000 version; (4) 

the Conservation Agreement (Hull’s 

Gulch Agreement) by and between Boise 

City and the U.S. Fish and Wildlife 

Service for Allium aasea (Aase’s onion), 

Astragalus mulfordiae (Mulford’s 

milkvetch), and Lepidium papilliferum 

(slickspot peppergrass), which was in 

place until it expired on October 22, 

2006, and (5) the Conservation 

Agreement for slickspot peppergrass 

(Lepidium papilliferum) at the Boise 

Airport, Ada County, Idaho. These five 

agreements and plans include a wide 

array of conservation measures to 

address the need to maintain and 

enhance slickspot peppergrass, and to 

potentially avoid or reduce adverse 

effects that might occur in relation to 

various types of activities. We recognize 

that many of the conservation efforts 

identified in the plans are having 

conservation benefits for the species, 

particularly as they relate to limiting the 

effects of wildfire and livestock use. We 

believe conservation efforts are 

important for this species because, 

while we do not have sufficient 

information to determine that potential 

threats are having a population level 

impact on the species, further research 

is necessary. To the extent that there are 

effects from activities, these 

conservation efforts should offset them. 

We evaluated conservation efforts 

within each plan under PECE (60 FR 

15100). PECE is relevant in situations 

where it is necessary to determine 

whether individual conservation efforts 

that have not been implemented, or that 

have been implemented but have not yet 

demonstrated whether they are 

effective, are sufficiently certain to be 

implemented and effective so as to have 

contributed to the elimination or 

adequate reduction of one or more 

threats to the species identified through 

our threats analysis conducted pursuant 

to section 4(a)(1) of the Act. In this case, 

the efforts that met the standard in PECE 

for sufficient certainty of 

implementation and effectiveness were 

not used as a basis for our conclusion, 

because our analysis did not show that 

the species met the definition of 

threatened or endangered. However, this 

does not mean that conservation efforts 

which have yet to be implemented, or 

which have yet to be demonstrated to be 

effective, are unimportant. In fact we 

strongly encourage continued 

implementation of all on-going and 

planned conservation efforts, as they 

can contribute to maintaining or 

improving the status of L. papilliferum. 

Issue 4: There were several comments 

regarding the use of available 

monitoring and survey data in 

determining the historical and existing 

distribution, population size, and trend 

information for Lepidium papilliferum. 

One commenter suggested there have 

been no comprehensive systematic 

surveys for L. papilliferum, and 

therefore, we do not fully understand 

the distribution or status of the species. 

Numerous commenters stated that 

monitoring protocols and methods used 

to gather data regarding L. papilliferum 

trends and distribution were biased 

toward documenting declines, were 

insufficient, or were poorly timed, and 

therefore conclusions are poor. Several 

commenters stated that there is no clear 

relationship between L. papilliferum 

trends and threat factors affecting the 

species. Some commenters suggested 

that the data demonstrate a negative 

population trend for L. papilliferum; 

other commenters suggested the data are 

inconclusive, and no trend can be 

determined. One commenter thought 

the trend from 2004 to 2005 was 

positive or stable due to implementation 

of the CCA, a wet spring, and a minimal 

wildfire season. Another commenter 

identified that the number of extant EOs 

have increased from 45 in 1998 to 85 in 

2006, and there has been only 1 EO that 

has been extirpated since 1955. Several 

commenters cited information relating 

L. papilliferum annual abundance to 

precipitation, while other commenters 

disputed the claim that annual 

abundance is related to precipitation. 

Several commenters stated that the 

number of element occurrences has 

increased from 1998 (45 extant EOs) to 

2006 (85 extant EOs). 

Several commenters thought that the 

soil type (slickspots) used by Lepidium 

papilliferum is a limited resource that is 

not reforming, because the processes 

that originally created it no longer 

occur. Slickspots being modified, 

altered, or developed are lost to the 

ecosystem forever. 

Our response: In this determination, 

we have reviewed and considered 

scientific and commercial data 

contained in over 75 technical reports, 

published journal articles, and other 

documents, including nearly 30 reports 

received since January 22, 2004. We 

must base our listing determination for 

Lepidium papilliferum on the best 

available data regarding the plant’s 

current known population status, the 

known condition of its habitat, and the 

current factors affecting the species, 

along with ongoing conservation efforts, 

as described in the Summary of Factors 

Affecting the Species section of this 

final determination. We also 

acknowledge that uncertainties exist. 

While a systematic survey, utilizing 

similar techniques, has not been 

conducted for Lepidium papilliferum 

range-wide, at least 30 separate survey 

efforts for L. papilliferum have occurred 

(Baczkowski 2006; USFWS 2006d). 

Some of these surveys were within the 

known range of L. papilliferum habitat, 

and others were outside of the known 

distribution, for example, in the State of 

Oregon, in the Saylor Creek area 

between the Snake River Plain and the 

Owyhee Plateau, and the City of 

Hagerman. In 2003, for example, 2,350 

acres were surveyed in the Saylor Creek 

area between the Snake River Plain 

metapopulations and the Owyhee 

Plateau metapopulations. During these 

surveys, 1,727 slickspots were 

documented, but no L. papilliferum 

individuals were found (U.S. Air Force 

2003, p. 16). We agree that undiscovered 

sites occupied by L. papilliferum likely 

exist. Inventories for L. papilliferum 

have not been completed on the 

majority of private lands within its 

range due to restricted access. Recent 

discoveries of new occupied slickspot 

sites and new EOs since 1998 have not 

added substantially to our knowledge of 

where the species exists. For example, 

an inventory survey at the OTA in 2005 

found 365 new slickspots with L. 

papilliferum all within the range of 

known habitat on the OTA (URS 


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Corporation 2005, p. 6). Since 2003, 16 

new EOs on approximately 50 ac (28 ha) 

(0.4 percent of the total acreage) have 

been documented, all within 3 mi (4.8 

km) of previously existing EOs (Colket 

et al. 2006, Tables 1 to 14). Although 

there has been only one documented 

extirpation since 1955, up to 9 small 

and isolated EOs had no plants detected 

during one or more recent monitoring 

surveys. 

Numerous monitoring efforts have 

been conducted for Lepidium 

papilliferum, including population 

trend monitoring transects at the OTA 

(IDARNG 2005) completed since 1991, 

demographic monitoring at the OTA 

from 1993 to 1996 (Meyer et al. 2005), 

Habitat Integrity Index (HII) monitoring 

done by the Idaho CDC at L. 

papilliferum EOs range-wide conducted 

from 1998 to 2002 (Mancuso and 

Moseley 1998; Mancuso et al. 1998; 

Mancuso 2000; Mancuso 2001; Mancuso 

2002), Habitat Integrity Population (HIP) 

monitoring built on HII monitoring at L. 

papilliferum EOs range-wide conducted 

by the Idaho CDC in 2004 and 2005 

(Colket 2005a, Colket 2005b), and 

monitoring done at the Juniper Butte 

Range in 2003 and 2005 (U.S. Air Force 

2003). HIP monitoring, the most 

extensive range-wide effort to date, was 

developed by the Idaho CDC in 

conjunction with the L. papilliferum 

Technical Team to statistically analyze 

and detect trends in L. papilliferum and 

its habitat (the technical team includes 

IDARNG, BLM, Air Force, the Service, 

Idaho Department of Agriculture, and 

other interested parties) (Colket 2005a, 

p. 3). Both the HII and HIP monitoring, 

because of the difficulties associated 

with tracking numbers of L. 

papilliferum individuals across years, 

utilize habitat information as a metric of 

L. papilliferum health (Mancuso et al. 

1998, pp. 1 to 7). 

Because of the fluctuations in 

Lepidium papilliferum numbers 

associated with precipitation (Meyer et 

al. 2005, pp. 4, 12, 15; Palazzo et al. 

2005, p. 9; Menke and Kaye 2006b, p. 

10), determining trends requires longterm monitoring data sets. Two longterm monitoring data sets in which we 

see a downward trend in recent years in 

numbers of individuals that do not 

mimic precipitation are the population 

trend monitoring transect data and 

special use plot data at the OTA. In 

contrast, an analysis by Palazzo et al. 

(2005, p. 9) for all 4 years of HII data 

found a relationship (p-value less than 

0.01) between February to June 

precipitation and numbers of L. 

papilliferum. In their analysis of rangewide HII and HIP data collected from 

1998–2002 and 2004 (no data was 

collected in 2003), Menke and Kaye 

(2006b, p. 10) further refined this 

relationship and found a strong positive 

relationship between precipitation from 

March through May and L. papilliferum 

abundance. In contrast to the 

monitoring data from OTA, the rangewide data shows that L. papilliferum 

continues to track consistently with 

precipitation throughout all years of the 

data set (Menke and Kaye 2006b, p. 10 

and Figs. 1, 2). We consider this rangewide data to be the best available at this 

time. 

The conditions that allowed for the 

formation of slickspots in southwestern 

Idaho are thought to have occurred 

during a wetter Pleistocene climate 

(Nettleton and Petersen 1983, p. 191; 

Seronko 2006). Under natural 

conditions, several hundred years may 

be necessary to alter or lose slickspots, 

generally through climate change or 

severe natural erosion (Seronko 2006). 

Meyer and Allen (2005, p. 9) suggest 

that if sufficient time passes following 

the disturbance of slickspot soil layers, 

it is possible that slickspots can reform 

similar to their pre-disturbance 

configuration. 

Issue 5: Numerous commenters 

provided information or opinions 

regarding how various threats may or 

may not affect Lepidium papilliferum, 

its habitat, and its possible probability 

of extirpation. Threats specifically 

mentioned included residential, 

commercial, and agricultural 

development; military training; OHV 

use; nonnative, invasive plant species; 

wildfire; wildfire rehabilitation methods 

(including drill seeding and invasive, 

nonnative plant seedings); 

fragmentation; soil disturbance; 

herbicide spraying; wildlife grazing; 

herbivory; and agricultural pesticides 

(e.g., insecticide for grasshoppers or 

Mormon crickets) affecting L. 

papilliferum pollinators. One 

commenter suggested that the decreased 

quality of sagebrush grassland (steppe) 

habitat is the primary problem with the 

apparent decline of L. papilliferum. 

Our response: Our evaluation of the 

significance of the various threats across 

the range of Lepidium papilliferum is 

discussed in the Summary of Factors 

Affecting the Species section of this 

final determination. We analyzed the 

adequacy of existing regulatory 

mechanisms, including the effectiveness 

of ongoing, recently implemented, and 

proposed conservation efforts that 

attempt to conserve L. papilliferum in 

three conservation agreements, and two 

INRMPs from the IDARNG and the U.S. 

Air Force. The primary factors 

impacting L. papilliferum and its 

surrounding habitat include habitat 

degradation and modification of the 

sagebrush-steppe ecosystem from the 

current wildfire regime (i.e., increasing 

frequency, size, and duration of 

wildfires), invasion of nonnative weed 

species (e.g., cheatgrass), effects of 

livestock use (e.g., trampling and 

disruption of soils), and habitat loss due 

to agricultural and urban development. 

Less important factors that may affect 

the species include effects from 

rangeland revegetation projects, wildfire 

management practices, recreation, and 

military use. Herbivory is reported as 

sparse or at low levels, and is mainly by 

insects. Herbivory impacts to L. 

papilliferum from native ungulates such 

as elk, deer, and antelope have not been 

observed. However, pronghorn antelope 

tracks and droppings (U.S. Air Force 

2003, p. 14), and elk tracks and 

droppings (State of Idaho et al. 2006, 

Appendix A) have been infrequently 

documented in slickspots that support 

L. papilliferum. Herbicide spraying was 

not considered by the Expert Panel to be 

an important threat to L. papilliferum, 

and is not discussed in this listing 

determination. While the decreased 

quality of sagebrush-steppe and the 

development and implementation of 

successful habitat restoration may 

impact the species, we have found no 

correlation to date between the 

existence of these threats and 

population numbers. 

Issue 6: Several comments referred to 

the effects of livestock use on Lepidium 

papilliferum and its habitat. They 

suggested that livestock use (past, 

current, or future) adversely affects L. 

papilliferum by trampling and 

uprooting individual plants, 

transporting nonnative invasive seeds, 

disturbing slickspot habitat soil crusts, 

burying L. papilliferum seeds to a soil 

depth at which germination cannot 

occur, accelerating erosion of slickspots, 

compacting soils, and changing 

slickspot soil chemistry through the 

deposition of manure. 

Conversely, several commenters 

suggested that livestock use has 

minimal effects and can even provide 

beneficial effects to Lepidium 

papilliferum and its habitat. One 

commenter suggested that only three 

documented examples exist in which 

livestock use has been implicated as the 

primary factor in either a reduction or 

elimination of L. papilliferum from a 

given area. In each case, the incident 

was isolated and occurred prior to 

implementation of the CCA. Several 

commenters suggested that L. 

papilliferum co-evolved with historical 

livestock use and wild ungulate grazing 

pressure; therefore the impact of 

existing livestock use is as likely to be 


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beneficial as it is to be adverse, although 

effects generally remain unknown. 

Commenters suggested that potential 

benefits to L. papilliferum from 

livestock use include reduced 

frequency, intensity, and magnitude of 

wildfire; reduced nonnative invasive 

annual grasses; and improved 

germination of L. papilliferum seeds as 

a result of abrasion and reduced 

physical resistance of the surface soil 

crust. One commenter suggested that 

without authorized livestock grazing 

permits on Federal lands, some 

conservation benefits would not occur, 

including weed control, wildfire 

suppression, habitat rehabilitation, and 

a ready source of information regarding 

the land upon which ranchers run their 

livestock. Other commenters suggested 

that insufficient information exists, so 

we cannot draw conclusions regarding 

the effects of livestock use on L. 

papilliferum and its habitat. 

Our response: The most visible effect 

on Lepidium papilliferum and its 

slickspot habitat from livestock use is 

trampling impacts. Penetrating 

trampling is defined as livestock 

trampling of water-saturated slickspot 

soils that break through the restrictive 

soil layer (see Ecology and Habitat 

section above). Penetrating livestock 

trampling can affect the fragile soil 

layers of slickspots (Meyer et al. 2005, 

pp. 21, 22; Seronko 2004, pp. 1, 2), 

especially when it occurs during wet 

periods when slickspots are most 

vulnerable to disturbance. Penetrating 

trampling also potentially affects the 

seed bank for L. papilliferum by pushing 

the seeds below their ability to 

germinate (i.e., below 1.5 in (3 cm)) 

(Meyer et al. in press, pp. 3, 24, 25). 

Livestock use at an appropriate level, 

and during dry conditions, may reduce 

the spread of nonnative annual grasses 

at some L. papilliferum sites. However, 

using livestock to control nonnative 

annual grasses would need to occur 

during early spring when the grasses are 

growing strongly, and spring is when 

slickspots are most likely to be wet and 

most susceptible to damage. Responsive 

management, involving quickly 

removing livestock during rain events 

and moving them regularly to prevent 

soil disturbance, would be difficult over 

large areas. 

Livestock use has been documented 

(Colket et al. 2006, Appendix C) within 

62 of the 75 Lepidium papilliferum EOs 

for which habitat information has been 

collected (49 of 60 on the Snake River 

Plain and 13 of 15 on the Owyhee 

Plateau). Penetrating hoof prints have 

been documented within 21 EOs on the 

Snake River Plain, and 9 on the Owyhee 

Plateau (Colket et al. 2006, Appendix 

C). 

Data limitations have made it difficult 

to establish impact (or effect) thresholds 

from livestock management activities for 

Lepidium papilliferum. Based on a 

single year of HIP data (2004), there was 

no correlation between L. papilliferum 

abundance in the short-term and total 

livestock print cover or cover of prints 

penetrating to the slickspot clay layer 

(Menke and Kaye 2006b, p. 15). The HIP 

data are observational in nature; 

controlled experiments are needed to 

more accurately assess the effects of 

livestock on L. papilliferum and its 

habitat. At this time we have no data 

that long-term declines in abundance 

will arise from livestock grazing. 

Adaptive management techniques for 

areas occupied by L. papilliferum and 

affected by livestock use could result in 

new information from ongoing and 

proposed livestock use studies and 

monitoring conservation efforts for the 

species. We anticipate that additional 

information regarding L. papilliferum 

and livestock use, from research 

currently underway by the U.S. Air 

Force and University of Idaho will be 

available for use in species 

conservation. 

A more complete discussion on the 

effects of livestock use on Lepidium 

papilliferum and its habitat is found in 

the Summary of Factors Affecting the 

Species section. 

Issue 7: One commenter suggested 

that wildfire historically (prior to 

European influence) occurred on a 60- 

to 100-year frequency and resulted in 

small burned areas where wind erosion 

could scour slickspots, maintaining the 

thin silt layer on the slickspot and the 

mini-playa as a depression. Wind scour 

likely occurred, since the only species 

growing on the slickspot was Lepidium 

papilliferum. With exotic species 

currently occupying slickspots, wind 

erosion may not be effectively scouring 

them, and in fact, deposition may be 

occurring. One commenter suggested 

that historical wildfire intervals in 

Wyoming big sagebrush communities 

were much longer, and some areas 

rarely, if ever, burned. 

Conversely, one commenter stated 

that while an abundance of information 

exists regarding wildfire in Lepidium 

papilliferum habitat, no long-term 

monitoring data confirmed the 

significance of its effect on L. 

papilliferum. 

Our response: As previously stated in 

the July 15, 2002, proposed rule (67 FR 

46441) and January 22, 2004, document 

to withdraw the proposed rule (69 FR 

3094), wildfire affects Lepidium 

papilliferum EOs throughout the 

species’ range. Where habitat 

information is known, 42 of 60 EOs on 

the Snake River Plain and 6 of 15 on the 

Owyhee Plateau have been at least 

partially burned; 57 EOs on the Snake 

River Plain and 12 on the Owyhee 

Plateau have adjacent landscapes that 

are at least partially burned (Colket et al. 

2006, Appendix C). 

Current research indicates wildfire 

frequency in the sagebrush-steppe 

ecosystem throughout the range of 

Lepidium papilliferum has increased, 

from a historical average of once every 

60 to 110 years to once every 5 years at 

many sites, due to the invasion of 

nonnative annuals such as cheatgrass 

that became common on the Snake 

River Plain rangelands in the 1950’s 

(Wright and Bailey 1982, p. 158; Billings 

1990, pp. 307 to 308; Whisenant 1990, 

p. 4; USGS 1999, pp. 1 to 9; West and 

Young 2000, p. 262). Wildfires in 

cheatgrass tend to be larger, burn more 

uniformly, and leave fewer patches of 

unburned vegetation, all of which 

influence 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 sagebrushsteppe ecosystem into nonnative annual 

grasslands (USGS 1999, pp. 1 to 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 seed germination (Meyer 

and Allen 2005, pp. 6 to 7), and that 

allows weedy species to invade 

slickspots. See the Summary of Factors 

Affecting the Species section for a more 

complete discussion. 

Following wildfire events, the use of 

nonnative forage grass species (such as 

crested wheatgrass and Russian wildrye 

(Elymus junceus)) for rehabilitation can 

result in successful establishment of 

perennial plants, ultimately reducing 

and diminishing the impacts of 

cheatgrass and its accelerated wildfire 

frequency. The use of nonnative species 

that closely mimic the biology and 

ecological function of species native to 

the area may be a necessary first step in 

restoring a site following wildfire if 

native seed cannot be used due to 

limited availability or prohibitive cost. 

Of the known Lepidium papilliferum 

occurrences, 14 (19 percent) are located 

within areas where wildfire 

rehabilitation projects and crested 

wheatgrass seedings have occurred 

(Colket et al. 2006, Appendix C). 

Although L. papilliferum still occurs in 

these areas, most support lower 

numbers of plants (Mancuso and 


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Moseley 1998). See ‘‘Factor A’’ in the 

Summary of Factors Affecting the 

Species section below for a more 

detailed discussion. 

In a review of available information, 

the Expert Panel considered the current 

wildfire regime the most important 

factor affecting Lepidium papilliferum 

and its remaining habitat. 

Issue 8: One commenter expressed 

concerns regarding the U.S. Air Force’s 

development of the Juniper Butte Range 

(beginning in 1998) on the Owyhee 

Plateau where Lepidium papilliferum 

and its habitat occur. Development and 

use of this training range, along with 

resulting road construction, human 

presence, and proposed use of aerial 

flares/white phosphorus munitions 

during training exercises, has increased 

the risk of wildfire within a substantial 

portion of L. papilliferum’s range. 

Our response: Currently, the impact of 

military training activities does not 

represent a principal threat to Lepidium 

papilliferum. Both the IDARNG and 

U.S. Air Force are implementing 

conservation efforts that potentially 

avoid or reduce adverse effects of 

military training on the species and its 

habitat. Threats from military activities 

are localized and have little significance 

across the range of the species. 

Military activities within the range of 

Lepidium papilliferum include 

ordnance use, facility development, and 

transportation, all of which create an 

increased risk of wildfire and nonnative 

plant invasions. Military training occurs 

on the Snake River Plain at the OTA, on 

all or portions of seven EOs, and on the 

Owyhee Plateau at the Juniper Butte 

Range on a portion of one EO (sub EO 

704). The U.S. Air Force intends to use 

300 ac (121 ha) of the 11,070-acre 

Juniper Butte Range as the actual 

bombing impact area (U.S. Air Force 

2000). It anticipates that a small amount 

of ordnance will be dropped outside the 

bombing impact area, but the potential 

impact to L. papilliferum would likely 

be minimal. 

The Integrated Natural Resource 

Management Plan (INRMP) developed 

for the Juniper Butte Range provides 

management directions that ameliorate 

many of the threats from military 

training exercises. Range-wide, the most 

intact Lepidium papilliferum habitat 

occurs at the OTA, where similar 

conservation efforts have been 

implemented for 14 years (Colket et al. 

2006, pp. 22 to 23; Meyer 2005, p. 1). 

The IDARNG has implemented a variety 

of actions to meet the conservation 

needs of L. papilliferum, while still 

providing for military training activities. 

These actions include wildfire 

suppression efforts, and restricting 

ground-operated military training to 

areas where the plants are not found. 

Issue 9: Some commenters asserted 

the taxonomic status of Lepidium 

papilliferum is problematic and 

warrants further evaluation. For 

example, one commenter suggested that 

our failure to complete a genetic study 

of Lepidium montanum seriously flaws 

any discussion assessing L. papilliferum 

as a species on its own. A few 

commenters suggested that if L. 

papilliferum is a subspecies or variety it 

is not eligible for protection under the 

Act. 

Our response: Lepidium papilliferum 

was originally described as L. 

montanum var. papilliferum in 1900 by 

Louis Henderson. It was renamed L. 

papilliferum by Aven Nelson and J. 

Francis Macbride in 1913 based on its 

distinctive growth habit, short lifespan, 

and unusual pubescence (Nelson and 

Macbride 1913, p. 474). Hitchcock 

regarded L. papilliferum as L. 

montanum var. papilliferum, 

influencing several publications 

including Flora of Idaho and Flora of 

the Pacific Northwest (Hitchcock et al. 

1964, p. 516; Hitchcock and Cronquist 

1973, p. 170; Steele 1981, p. 55; Moseley 

1994, p. 2). In a review of taxa in the 

mustard family (Brassicaceae), Rollins 

(1993) maintained the species based on 

differences in the physical features 

between L. papilliferum and L. 

montanum such as: (1) L. papilliferum 

has trichomes (hair-like structures) 

occurring on the filaments of stamens 

(part of flower that produces pollen), 

and L. montanum does not; (2) all the 

leaves on L. papilliferum are pinnately 

divided, and L. montanum has some 

leaves that are not divided; (3) the shape 

of the silicle [silique] (seed capsule) of 

L. papilliferum is different from that of 

L. montanum; and (4) the silicle of L. 

papilliferum has no wings, or even 

vestiges of wings, at its apex (end of the 

capsule), unlike that of L. montanum 

(Rollins 1993, p. 578; Moseley 1994, p. 

2). 

A review of the taxonomic status by 

Lichvar (2002), using classic 

morphological features and study of 

herbarium specimens, concluded that L. 

papilliferum has distinct morphological 

features that warrant species 

recognition. Meyer et al. (2005, p. 17) 

described a life history contrast when 

compared to L. montanum regarding 

seed dormancy and the seed bank. L. 

papilliferum seeds can remain dormant 

(and viable) and persist in the seed bank 

for about 12 years, whereas L. 

montanum has largely non-dormant 

seeds (Meyer et al. 2005, p. 17). Most 

recently, L. papilliferum has been 

accepted as a distinct species by 

Intermountain Flora, a recognized 

regional text (Holmgren et al. 2005, p. 

259); the U.S. Department of 

Agriculture’s ‘‘PLANTS Database’’

(USDANRCS 2006); and the Biota of 

North America Project, the recognized 

taxonomic reference for the United 

States (ITIS 2006). 

The preliminary results of two studies 

on the genetics of Lepidium 

papilliferum recently became available. 

The first, based on a relatively small 

sample size and more limited 

methodology, found that L. papilliferum 

forms a distinct monophyletic group 

that is most closely related to L. 

fremontii (Smith 2006, pp. 5 to 7 and 

Fig. 1). The second, utilizing larger 

sample sizes and additionally applying 

the methodology of AFLP (amplified 

fragment length polymorphisms, 

recognized for greater resolution or 

discriminatory power in detecting 

genetic differentiation) (Mueller and 

Wolfenbarger 1999, pp. 389 to 393; 

Savelkoul et al. 1999, p. 3085)), found 

that L. papilliferum forms a distinct 

monophyletic group or subgroup, and 

indicates that it is most closely related 

to L. montanum var. montanum (Larson 

et al. 2006, p. 13, 15, and Fig. 4). These 

genetic studies are consistent with the 

interpretation that L. papilliferum is 

either a variety or subspecies of L. 

montanum, or that it is a full and 

distinct species that has recently 

diverged from L. montanum. Plant 

species and subspecies (or varieties) are 

eligible for protection under the Act. 

Issue 10: One commenter stated that 

very little scientific research has been 

conducted on Lepidium papilliferum, 

and subsequently very little peerreviewed literature is available for the 

species. Most of the information we 

have is based on technical reports and 

personal communications. 

Our response: The Act requires us to 

make listing decisions based on the best 

scientific and commercial data available 

at the time the decision is made (section 

4(b)(1)(A) of the Act). Following the 

August 19, 2005, Federal Court decision 

regarding our January 22, 2004, 

document to withdraw the proposed 

rule to list Lepidium papilliferum as 

endangered, we sought and received 

new scientific and commercial data 

pertaining to the species. We 

incorporated all relevant new 

information into the ‘‘Draft Best 

Available Information (BAI) for 

Slickspot peppergrass (Lepidium 

papilliferum)’’ document, which was 

updated from the 2003 version. We 

solicited public comment and peer 

review on the draft BAI document and 

requested additional scientific data 

pertaining to the species. We followed 


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1634 Federal Register / Vol. 72, No. 8 / Friday, January 12, 2007 / Proposed Rules 

our Information Quality Guidelines in 

preparing this final determination (see 

Information Quality Act discussion 

below). We also convened a panel of 

seven scientific experts (see Expert 

Panel discussion below) to review the 

available data pertaining to L. 

papilliferum prior to making this final 

determination. 

Information Quality Act 

In our review of the status of 

Lepidium papilliferum, we assembled 

information that addressed the current 

biological and ecological condition of 

the plant and its habitats. This 

information included reports from 

private industry, public universities, 

State and Federal resource agencies, 

published texts on a variety of biological 

topics, and peer-reviewed literature 

from the primary scientific journals. 

Additionally, we included unpublished 

scientific and commercial data , 

documents written and included in 

literature, and personal 

communications. Personal 

communications were used when they 

represented information that was 

pertinent and not available through 

other sources such as technical reports 

or published texts. 

We carefully evaluated each piece of 

data for its usefulness in the review 

process, and used those that contributed 

important information to the review. 

State and Federal government 

documents are generally considered to 

be of high utility, objectivity, and 

integrity. These documents are often 

subject to public review and comment, 

and State and Federal agencies generally 

employ the current standards in 

resource survey, monitoring, and 

analysis methodologies. The peerreviewed scientific literature and 

scientific textbooks are rigorously 

reviewed and edited at several levels 

before publication, and represent the 

highest degree of utility, objectivity, and 

integrity. 

In compiling this document, we tried 

to present the information in an 

accurate, clear, complete, and unbiased 

manner. Given that the data available on 

this species covered a wide spectrum 

from peer-reviewed literature to 

personal communications, we 

developed this document with the goal 

of providing a high degree of 

transparency regarding the source of 

data. 

We followed our Information Quality 

Act Guidelines in developing this 

document. These guidelines provide 

direction for ensuring and maximizing 

the quality of information disseminated 

to the public. The guidelines define 

quality as an encompassing term that 

includes utility, objectivity, and 

integrity. Utility refers to the usefulness 

of the information to its intended users, 

including the public. Objectivity 

includes disseminating information in 

an accurate, clear, complete, and 

unbiased manner and ensuring accurate, 

reliable, and unbiased information. If 

data and analytic results have been 

subjected to formal, independent peer 

review, we generally presume that the 

information is of acceptable objectivity. 

Integrity refers to the security of 

information, i.e., protection of the 

information from unauthorized access 

or revision to ensure that the 

information is not compromised 

through corruption or falsification. 

One of our goals in obtaining public 

comment and peer review of the draft 

BAI was to ensure that we were 

considering the best available data 

while accurately representing the source 

of the information. Background 

information on the taxonomy, 

distribution, abundance, life history, 

conservation actions, and needs of 

Lepidium papilliferum, and threats 

affecting the species, were derived from 

previous petition findings, previous 

Federal Register notices, Idaho’s 

Conservation Data Center EO records, 

and other pertinent references from 

1897 (when the species was first 

collected) through 2006. 

The supporting information, 

administrative finding, and other 

relevant materials can be reviewed in 

person at the address listed in the 

ADDRESSES section, or copies of 

information can be made available to 

you (see References Cited at the end of 

this rule). 

Summary of Factors Affecting the 

Species 

Section 4 of the Act and its 

implementing regulations (50 CFR part 

424) set forth the procedures for adding 

species to the Federal Lists of 

Endangered and Threatened Wildlife 

and Plants. A species may be 

determined to be an endangered or 

threatened species due to one or more 

of the five factors described in section 

4(a)(1) of the Act. The five listing factors 

are: (A) The present or threatened 

destruction, modification, or 

curtailment of its habitat or range; (B) 

overutilization for commercial, 

recreational, scientific, or educational 

purposes; (C) disease or predation; (D) 

the inadequacy of existing regulatory 

mechanisms; and (E) other natural or 

manmade factors affecting its continued 

existence. 

A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of its Habitat or Range 

Current Wildfire Regime 

The invasion of nonnative plant 

species, particularly annual grasses such 

as cheatgrass and medusahead 

(Taeniatherum caput-medusae), 

beginning in the early 1900’s has 

increased the amount and continuity of 

fine fuels across the landscape. As 

cheatgrass became more dominant on 

the rangelands of the Snake River Plain 

in the 1950’s, wildfire frequency 

intervals began to shorten from the 

historic average of between 60 to 110 

years to the current frequency intervals 

of less than 5 years in many areas on the 

Snake River Plain where Lepidium 

papilliferum resides (Whisenant 1990, 

p. 4) and within the sagebrush-steppe 

ecosystem as a whole (Wright and 

Bailey 1982, p. 158; Billings 1990, pp. 

307 to 308; USGS 1999, pp. 1 to 9, West 

and Young 2000, p. 262). Wildfires tend 

to be larger and burn more uniformly 

when annual grasses are present, 

resulting in fewer patches of unburned 

vegetation, which can affect the post-fire 

recovery of native sagebrush-steppe 

vegetation (Whisenant 1990, p. 4). This 

altered wildfire regime has contributed 

to the conversion of vast areas of 

sagebrush-steppe ecosystem into 

nonnative annual grasslands (USGS 

1999, pp. 1 to 9). More frequent 

wildfires 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 to 7). 

Of the 75 EOs for which habitat 

information is known, 48 (42 of 60 on 

the Snake River Plain and 6 of 15 on the 

Owyhee Plateau) have been at least 

partially burned, and 69 (57 on the 

Snake River Plain and 12 on the 

Owyhee Plateau) have adjacent 

landscapes that are at least partially 

burned (Colket et al. 2006, Appendix C). 

Within the Snake River Plain, 

approximately 448,917 acres (181,670 

ha) (28 percent) were burned between 

1970 and 2003 (calculated from USBLM 

2004). Within the Owyhee Plateau 

60,467 acres (24,470 ha) (47 percent) 

have burned between 1970 and 2003 

(calculated from BLM 2004). 

Table 3 shows the evidence of 

wildfire documented through HIP rangewide transect monitoring in 2005. 

Wildfire evidence can remain on the 

landscape for up to 20 years, and 

evidence documented in Table 3 

includes both recent and historical fires. 


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TABLE 3.—EVIDENCE OF WILDFIRE DOCUMENTED AT HIP TRANSECTS IN 2005 (COLKET 2005A, TABLES 1 AND 2) 

Number of transects at 

least partially burned 

Number of 

transects not 

burned 

Total 

transects 

Adjacent landscapes within 

0.31 mi (500 m) of EOs 

burned or partially burned 

Snake River Plain .............................................................. 26 31 57 45 

Owyhee Plateau ................................................................ 12 10 22 21 

Total ............................................................................ 38 41 79 66 

In a statistical analysis of HII data 

between 1998 and 2001, burned areas at 

the beginning of the study had depleted 

shrub and soil crust cover that persisted 

throughout the monitoring period 

(Menke and Kaye 2006a, p. iii). In 

addition, burned areas had less native 

plant cover, greater nonnative plant 

cover, increased slickspot perimeter 

compromise, and increased organic 

debris accumulation (Menke and Kaye 

2006a, p. iii). Similarly, in a statistical 

analysis of HII and HIP data between 

1998 and 2004, burned areas had less 

soil crust cover and higher nonnative 

plant cover (Menke and Kaye 2006b, p. 

3). Although the proportion of flowering 

plants was positively correlated with 

soil crust cover, there was no 

relationship between L. papilliferum 

plant abundance and soil crust cover or 

weedy species cover in slickspots based 

on the 2004 HIP data (Menke and Kaye 

2006b, p. 15). In their analysis, Menke 

and Kaye (2006b, p. 17) concluded that 

competition from weedy annual species 

does not appear to influence abundance 

of L. papilliferum plants in a given year, 

although it may influence reproductive 

output or other traits, and that past fire 

disturbance does not appear to 

significantly alter longer-term trends in 

plant abundance. Past fires have 

apparently degraded slickspot 

condition, as evidenced by lower soil 

crust cover and greater exotic species 

cover (Menke and Kaye 2006b, p. 19), 

however Lepidium papilliferum 

abundance was statistically similar 

between burned and unburned transects 

from 1998 to 2004 (Menke and Kaye 

2006b, p. 10), and the proportion of L. 

papilliferum in flower was similar 

between burned and unburned transects 

in 2004 (Menke and Kaye 2006b, p. 15). 

Past fires appear to have had a lasting 

negative impact on the plant community 

surrounding slickspots, including 

increased exotic species cover and 

decreased soil crust cover (Menke and 

Kaye 2006b, p. 19). Menke and Kaye 

(2006b, p. 17) note that the HII and HIP 

data are observational only, and 

controlled experiments are needed to 

more accurately assess the impacts of 

factors such as fire and grazing on L. 

papilliferum (Menke and Kaye 2006b, p. 

17). At this point, given the equivocal 

nature of the habitat integrity and 

population monitoring data, the effects 

of an altered sagebrush steppe wildfire 

regime on L. papilliferum need further 

study. We have no data at this point that 

indicates that fire has a long-term 

impact on the species abundance; the 

available data show no correlation 

between fire and L. papilliferum 

population numbers. 

Existing conservation measures 

designed to reduce the adverse effects of 

wildfire apply to approximately 96 

percent of Lepidium papilliferum’s 

occupied range. For example, the 

IDARNG, U.S. Air Force, and BLM will 

continue their rapid response or mutual 

support agreement for wildfire control. 

BLM has established wildfire 

suppression goals for management areas 

in the CCA (State of Idaho et al. 2006, 

Table 5). 

The military is implementing a 

number of efforts that address wildfire 

suppression that have been shown to be 

effective in certain respects at 

controlling this threat. However, we are 

not relying on the implementation of 

conservation measures to make this 

finding. Implemented and effective 

conservation measures will, however, 

help to counter habitat degradation 

generally and may help conserve the 

species. Since the late 1980s, the 

policies of the IDARNG included 

immediate wildfire suppression during 

military activities to prevent damage to 

intact sagebrush-steppe and Lepidium 

papilliferum sites within the OTA 

(IDARNG 2004, pp. 65 to 67). Seven 

occurrences of L. papilliferum occur 

within this area (Colket et al. 2006, pp. 

8 to 9). Since 2002, the U.S. Air Force 

has instituted a high-level rapid 

response for wildfire suppression on the 

Juniper Butte Range (U.S. Air Force 

2004, pp. 6–45 to 6–47). The U.S. Air 

Force addresses wildfire prevention 

through reducing standing fuels and 

weeds, planting fire-resistant vegetation 

in areas with a higher potential for 

ignition sources (e.g., along roads), and 

using wildfire indices to determine 

wildfire hazard ratings and restricting 

activities when the rating is extreme 

(U.S. Air Force 2004, pp. 6–45 through 

6–47). The BLM and IDARNG are 

continuing their mutual support 

agreement for wildfire suppression in 

the Snake River Birds of Prey National 

Conservation Area (IDARNG 2004, p. 

83). 

On the OTA, the reduction in 

wildfires within EOs has demonstrated 

that management efforts to suppress 

wildfire can be effective. The 7 EOs on 

the OTA represent nearly 40 percent of 

the total area occupied by Lepidium 

papilliferum (see Figure 1 above), and 

aggressive wildfire suppression has 

occurred for over 12 years. The 

feasibility of implementing rapid 

response wildfire suppression 

techniques elsewhere is complicated by 

the fact that many of the remaining L. 

papilliferum EOs are in remote areas 

away from wildfire control facilities. 

The current wildfire regime is 

interrelated with several other factors 

that may affect L. papilliferum, 

including the replacement of large areas 

of native vegetation with more 

flammable nonnative grasses, increased 

sedimentation of slickspots, and habitat 

fragmentation. While these effects may 

be occurring, the existing data do not 

correlate them with declines in 

abundance of L. papilliferum. 

Invasive Nonnative Species 

The most common nonnative annual 

grasses known to occur in Lepidium 

papilliferum’s habitat include 

cheatgrass and medusahead. Annual 

forbs most commonly associated with 

slickspots include clasping pepperweed 

(Lepidium perfoliatum), tumbleweed 

(also known as Russian thistle), tumble 

mustard (Sisymbrium altissimum) (also 

known as tall tumble mustard), and bur 

buttercup (Colket 2005a, p. 6). 

Nonnative plants may become 

established in L. papilliferum habitats 

by spreading through natural dispersal 

(unseeded) or may be intentionally 

planted through re-vegetation projects 

(seeded). Invasive nonnative plants can 

alter attributes of ecosystems, including 

geomorphology, wildfire regime, 

hydrology, microclimate, nutrient cycle, 

and productivity (Dukes and Mooney 

2003, pp. 1 to 35). They can also 

negatively affect native plants through 


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competitive exclusion, niche 

displacement, hybridization, and 

competition for pollinators; examples 

are widespread among taxa and 

ecosystems (D’Antonio and Vitousek 

1992, pp. 63 to 87; Olson 1999, p. 5; 

Mooney and Cleland 2001, p. 1). All 75 

EOs for which habitat information is 

available have nonnative, unseeded 

plants present (Colket et al. 2006a, 

Appendix C). 

The results from 2004 HIP monitoring 

revealed that all 71 HIP transects 

monitored within EOs (49 on the Snake 

River Plain and 22 on the Owyhee 

Plateau) had nonnative, unseeded plant 

cover. For example, within the Snake 

River Plain (49 transects), 1 had 

nonnative plant cover occurring over 50 

percent of the transect, 7 transects had 

nonnative plant cover between 25 and 

50 percent of the transect, and 10 

transects had nonnative plant cover 

between 10 and 25 percent. Two 

transects on the Owyhee Plateau had 

nonnative plant cover between 10 and 

25 percent (Colket 2005a, pp. 46 to 47). 

In their analysis of Lepidium 

papilliferum population trends in 

association with plant community 

trends and habitat quality based on HII 

and HIP monitoring data from 1998–

2002 and 2004, Menke and Kaye (2006b, 

p. 12) report that species diversity and 

species richness of the plant community 

had declined, but that exotic species 

cover and shrub cover had remained the 

same. Total exotic species cover and 

exotic grass cover was high in burned 

transects in all years (Menke and Kaye 

2006b, p. 15). Weedy species cover was 

higher in burned slickspots, but there 

was no significant correlation between 

weedy species cover and either 

abundance of L. papilliferum or 

proportion of L. papilliferum in flower 

(Menke and Kaye 2006b, p. 15). The 

authors note that although competition 

from weedy annuals does not appear to 

influence the short-term abundance of L. 

papilliferum, it may be influencing 

other plant traits or life history stages 

not assessed in this study (Menke and 

Kaye 2006b, p. 17). However, we have 

no data to corroborate that this threat 

will result in future declines in 

abundance. 

Existing conservation measures 

designed to reduce the potential adverse 

effects of nonnative, unseeded species 

apply to approximately 96 percent of 

Lepidium papilliferum’s occupied range 

(CCA, U.S. Air Force INRMP, IDARNG 

INRMP). Conservation measures 

identified within the CCA include 

protecting remnant blocks of native 

vegetation, prioritized weed control 

measures at L. papilliferum EOs, 

protective weed control techniques, 

revegetation requirements in disturbed 

areas, education on nonnative species 

and their spread, vehicle wash points 

and stations, and research support and 

funding for nonnative species control 

(State of Idaho et al. 2006, pp. 131 to 

132). 

The military has a number of ongoing 

efforts to suppress non-native species. 

The IDARNG requires all military 

vehicles entering the OTA from a 

distance greater than 50 mi (80.4 km) to 

be washed at a high-pressure wash rack 

facility to prevent weed seed 

introduction. Noxious weeds at small 

sites are hand-pulled when they are 

found by IDARNG staff, and noxious 

weed sites on the OTA are reported 

annually to BLM for treatment (IDARNG 

2004, p. 67). The U.S. Air Force reduces 

the spread of exotic annual species by 

reseeding disturbed areas with native 

vegetation to the maximum extent 

practicable, eradicating noxious weeds 

prior to spread, and requiring cleaning 

of U.S. Air Force vehicles and 

equipment on a wash rack upon return 

to base. They avoid the use of pesticides 

within 25 feet of slickspots and use 

pesticides only if wind conditions are 

favorable (away from the slickspot) to 

prevent the loss of Lepidium 

papilliferum (U.S. Air Force 2004, pp. 

R–4, R–5). 

The OTA has demonstrated that 

management efforts to suppress 

wildfire, rehabilitating areas with native 

species, and using wildfire 

rehabilitation activities with minimal 

ground disturbance can be effective in 

reducing the wildfire threat and 

reducing rates of spread of nonnative 

unseeded species. Nonnative, unseeded 

species are increasing at the OTA, 

although not as rapidly as at other areas 

where these conservation efforts are not 

being implemented or have only been 

implemented for a short period. 

We have no evidence that correlates 

invasive species presence with declines 

of L. papilliferum or the proportion of L. 

papilliferum in flower (Menke and Kaye 

2006b, p. 15). 

Livestock Use 

Trampling of Lepidium papilliferum 

and slickspots can result from livestock 

use. Table 4 documents the extent of 

livestock use at HIP transects. Livestock 

trampling can affect the soil layers of 

slickspots (Colket 2005a, p. 34; Meyer et 

al. 2005, pp. 21 and 22; Seronko 2004, 

pp. 1 and 2). 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. 

Livestock trampling of water-saturated 

slickspot soils that breaks through the 

restrictive layer, which is 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; Seronko 2004, pp. 1 and 2). 

Penetrating trampling, which occurs 

when slickspots are wet, also has the 

potential to affect the seed bank for L. 

papilliferum. Meyer and Allen (2005, 

pp. 6 and 7); seed emergence success 

decreased with increasing depth from a 

mean of 54 percent at the shallowest 

plant depth of 2 mm to a mean of 5 

percent at 30 mm depth. 

TABLE 4.—LIVESTOCK USE DOCUMENTED AT ELEMENT OCCURRENCES AND HIP TRANSECTS IN 2004 (COLKET et al. 

2006, APPENDIX C). 

[Evidence of livestock use does not infer effects throughout a transect or EO] 

Evidence of 

penetrating 

trampling (EO) 

Evidence of 

penetrating 

trampling (HIP 

Transects) 

Snake River Plain .................................................................................................................................................... 21/60 19/49 

Owyhee Plateau ...................................................................................................................................................... 9/15 20/22 

Total .................................................................................................................................................................. 30/75 33/71 


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In a statistical analysis of HII data 

from 1998 to 2001, it was found that 

recent livestock use had neutral effects 

on Lepidium papilliferum, slickspot 

attributes, and plant community 

attributes (Menke and Kaye 2006a, p. 

iii). Recent livestock use estimated by 

HIP monitoring in the year 2004 

resulted in decreased soil crust cover in 

slickspots, decreased vascular plant 

cover, and decreased plant litter cover 

in the surrounding plant community 

(Menke and Kaye 2006b, p. 3). There 

was no significant correlation between 

total livestock print cover or cover of 

prints penetrating to the slickspot clay 

layer and abundance of L. papilliferum, 

and both the abundance of L. 

papilliferum per slickspot and 

proportion of flowering plants was 

similar between grazed and ungrazed 

transects for the single year of data 

reported in 2004 (Menke and Kaye 

2006b, p. 15). In the surrounding plant 

community, grazed and ungrazed 

transects had similar species richness, 

diversity, and soil crust cover, but total 

vascular plant cover and plant litter 

cover were significantly lower in grazed 

transects (Menke and Kaye 2006b, pp. 

15 and 16). 

Livestock trampling events that are 

most likely to adversely affect Lepidium 

papilliferum usually occur when large 

numbers of livestock are concentrated 

on or around slickspots that are 

saturated with water (Hoffman 2005; 

Meyer et al. 2005, pp. 21 to 22). 

Saturated conditions typically exist for 

short periods each year and may never 

occur in some (drought) years (Hoffman 

2005). Predicting when soils will be wet 

in a climate with few and inconsistent 

precipitation events is difficult. 

Consequently, managing livestock to 

avoid penetrating tramping events is 

difficult. Supplemental salt and 

watering sites can alter livestock 

distribution, and depending on location, 

can increase or decrease trampling of 

slickspots. 

At least two penetrating trampling 

events have been suggested as the cause 

of substantial losses in Lepidium 

papilliferum numbers. In 1996, when 

other sites at the OTA had a reasonably 

high numbers of L. papilliferum 

individuals, a study site referred to as 

the ‘‘States site’’ experienced substantial 

declines. In 1993, this site had 

thousands of plants. In the spring of 

1996, a trampling event disrupted or 

buried the in-situ seed bank (Meyer et 

al. 2005, pp. 21 and 22). Since this 

trampling event, fewer than 10 plants 

have been observed at the site despite 

yearly visits (Meyer et al. 2005, pp. 21 

and 22). In another study area, four of 

five sites experienced increases in plant 

numbers; the fifth site, Glenn’s Ferry, 

was the only one that incurred a 

trampling event, and the only one with 

a dramatic reduction in L. papilliferum 

numbers (Robertson 2003b, p. 8). 

Research designed to specifically 

examine the relationship between 

livestock use trampling effects and L. 

papilliferum is currently being 

conducted by University of Idaho and 

the State of Idaho in cooperation with 

us (State of Idaho et al. 2006, p. 119). 

However, at this point we have nothing 

but this anecdotal evidence to indicate 

a threat. Information we do have does 

not suggest that habitat threats are 

correlated with declines in species 

population levels. 

There are also indirect effects from 

livestock use that have impacted the 

sagebrush-steppe ecosystem. The spread 

of both native and nonnative plant 

species has been attributed to livestock 

use (Frost and Launchbaugh 2003, pp. 

43 to 45). The spread of cheatgrass on 

the Snake River Plain has been 

attributed to several causes, including 

the past practice of heavy livestock use 

in the late 1800s (Mack 1981, pp. 145 

to 165). Today, nonnative, annual plants 

such as cheatgrass are so widespread 

that they have been documented 

spreading into areas that have not been 

disturbed (Piemeisal 1951, p. 71; 

Tisdale et al. 1965, pp. 349 and 351; 

Stohlgren et al. 1999, p. 45); therefore, 

the absence of livestock use does not 

protect the landscape from invasive, 

nonnative weeds (Frost and 

Launchbaugh 2003, p. 44). With careful 

management, livestock grazing may be 

used as a tool to select for certain native 

species or even to control cheatgrass 

(Frost and Launchbaugh 2003, p. 43). 

There was no significant difference in 

cover of exotic plant species in 

slickspots between grazed and ungrazed 

areas in the 2004 HIP dataset, although 

soil crust cover was significantly lower 

in grazed transects (Menke and Kaye 

2006b, p. 19). Analysis of HII data from 

1999 through 2001 found no effect of 

livestock grazing on slickspot perimeter 

integrity, weedy species density, 

perennial forb or grass establishment, or 

organic debris accumulation in 

slickspots (Menke and Kaye 2006a, p. 

10). Cumulative livestock sign had a 

significant negative correlation with 

exotic grass dominance around 

slickspots (Menke and Kaye 2006a, p. 

11) and with the frequency of slickspots 

with dense weedy annuals in 2001 

(Menke and Kaye 2006a, p. 10). The 

analysis of grazing effects was limited 

since the HII data were observational 

only (no controlled experiments were 

performed), all areas were likely grazed 

at some point in the past, and grazing 

effects could only be observed in 

habitats that had been burned in the 

past (Menke and Kaye 2006a, p. 18). 

The conservation plans (CCA, U.S. 

Air Force INRMP, IDARNG INRMP) 

contain numerous measures to avoid, 

mitigate, and monitor effects of 

livestock use on the species. Livestock 

grazing conservation measures 

implemented through the CCA and the 

U.S. Air Force INRMP apply to all 

Federal and State-managed lands (96 

percent of the acreage) within the 

occupied range of Lepidium 

papilliferum. Conservation measures 

prescribed by the CCA include 

minimum distances for placement of 

salt and water troughs away from 

occurrences of the species, and several 

troughs and salt blocks have been 

moved as a result of these measures 

(State of Idaho et al. 2006, p. 133; State 

of Idaho et al. 2005). The CCA also 

includes measures to reduce trampling 

during wet periods, including trailing 

(moving cattle to, or between, 

allotments repeatedly on the same path) 

restrictions (State of Idaho et al. 2006, 

pp. 132 to 134). High priority EOs, as 

identified in the CCA, tend to have more 

restrictive conservation measures, such 

as no early spring grazing, fencing to 

exclude livestock, and delaying turnout 

of livestock when soils are saturated 

(State of Idaho et al. 2006, pp. 133 to 

134). High priority EOs were designated 

based on existing habitat quality, 

geographic location relative to other 

existing EOs, minimal land use 

activities, the absence or presence of 

resources to address threats, and the 

need to preserve enough EOs 

throughout the species’ range to prevent 

extinction in case of a catastrophic 

event. In high priority EOs, greater 

emphasis is placed on protection and 

restoration of habitat. BLM has changed 

the season of grazing use from spring to 

fall, and implemented a deferred 

rotation management system on some 

allotments to protect flowering annuals 

from grazing (State of Idaho et al. 2006, 

pp. 133 to 134). 

Under the revised Juniper Butte Range 

INRMP, the U.S. Air Force will continue 

to use livestock throughout the majority 

of the Juniper Butte Range to reduce the 

amount of standing grass biomass to 

reduce wildfire risk (U.S. Air Force 

2004, pp. 6–37 to 6–39). The grazing 

component plan for the INRMP states 

that livestock use will occur annually 

for up to 60 days while the bombing 

range is shut down for clean-up and 

target maintenance. The shutdown 

period lasts a maximum of 60 days 

within a 90-day period, from April 1 

through June 30 (U.S. Air Force 2000, 

pp. B–18 to B–21). The INRMP 


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emphasizes avoiding grazing when 

slickspots are wet in order to reduce 

trampling of slickspot habitats. It also 

provides guidance for annual 

monitoring of slickspot soil moisture to 

determine livestock turnout dates for 

Juniper Butte Range (U.S. Air Force 

2000, pp. B–18 to B–21). The U.S. Air 

Force established three fenced areas of 

173 ac (70.0 ha), 8 ac (3.2), and 30 ac 

(12.1 ha), respectively, in 2002, with the 

intent of promoting Lepidium 

papilliferum research and seed 

collection (Binder 2006), when 

compatible with the Air Force mission. 

There was no significant correlation 

between total livestock print cover or 

cover of prints penetrating to the 

slickspot clay layer and abundance of L. 

papilliferum, and both the abundance of 

L. papilliferum per slickspot and 

proportion of flowering plants was 

similar between grazed and ungrazed 

transects for the single year of data 

reported in 2004 (Menke and Kaye 

2006b, p. 15) and no other data were 

available that indicated otherwise. 

Therefore, we do not believe that 

livestock impacts are a threat to the 

species. 

Residential and Agricultural 

Development 

Past residential and agricultural 

development has been responsible for 

five documented local extirpations and 

four probable local extirpations of 

Lepidium papilliferum (Colket et al. 

2006, p. 4). The long-term viability of L. 

papilliferum occurrences on private 

land on the Snake River Plain has the 

potential to be compromised due to the 

continuation of residential and urban 

development in and around Boise 

(Moseley 1994, p. 20). Today, all or 

portions of 18 L. papilliferum EOs 

covering 457 acres (3.5 percent) (not 

including EOs managed by cities or 

counties) occur on private land. 

However, half of these 18 EOs are 

smaller than one acre, and most are 

classified as having fair to poor habitat 

quality (Colket et al. 2006, pp. 39 to 41). 

Residential and agricultural 

development can affect L. papilliferum 

and slickspot habitat through habitat 

conversion, increased nonnative plant 

invasions, increased off-highway 

vehicle use, increased wildfire, changes 

to insect populations, and increased 

fragmentation. Future residential and 

agricultural development on private 

land occupied by the species is a 

potential threat that is limited to 3.5 

percent of the total known element 

occurrence acreage, therefore such 

development is not a significant threat. 

Gravel or cinder mining may affect 

Lepidium papilliferum on State and 

Federal lands (Mancuso 2000, p. 13). 

One site was impacted by illegal mining 

activity in 1999 on BLM and private 

lands (DeBolt 1999). No other impacts 

from gravel or cinder mining have been 

documented, therefore gravel or cinder 

mining does not constitute a significant 

threat to the species. 

Power, gas, and other lines, and 

related roads, affect and fragment 

Lepidium papilliferum EOs. Utility lines 

and accompanying roads have been 

documented running through at least 

four EOs, gas lines run through two EOs, 

and roads run through at least six EOs 

(Colket et al. 2006, Appendix C). In 

addition to direct habitat destruction, 

these corridors allow off-road vehicle 

access and increase the chance of 

nonnative plant invasions and humanignited wildfires. Transportation 

corridors associated with development 

also increase the probability of humanignited wildfires and the spread of 

nonnative, invasive plants. Future 

developments associated with power, 

gas, other lines, and related roads 

through habitat occupied by the species 

may be a potential threat depending 

upon design and mitigation measures 

associated with the developments. But 

at this time we have no data that such 

development constitutes a significant 

threat to the species. 

Of the Lepidium papilliferum EOs for 

which habitat information has been 

collected, 14 of 75 (13 of 60 on the 

Snake River Plain and 1 of 15 on the 

Owyhee Plateau) have development 

(e.g., utility lines, mining, agricultural 

development, and residential 

development) within them, and 28, all 

on the Snake River Plain, have 

development adjacent to them within 

0.31 mi (500 m) (Colket et al. 2006, 

Appendix C). On the Owyhee Plateau, 

one EO has development occurring 

within it, and no EOs have development 

within 0.31 mi (500 m) (Colket et al. 

2006, Appendix C). 

Within the Snake River Plain, an 

estimated 327,549 ac (132,554 ha) (20 

percent) has been converted to 

agriculture (IDWR 1999), and 94,974 ac 

(38,435 ha) (6 percent) has been 

converted to urban areas (University of 

Idaho 2001). 

Development was not a parameter that 

was measured in 2004 through the HIP 

transect monitoring program (Colket 

2005a). In 2005, 79 HIP transects were 

monitored (57 on the Snake River Plain 

and 22 on the Owyhee Plateau); of these 

transects only one transect on the Snake 

River Plain had development occurring 

at the transect (in this case residential/ 

commercial). Monitoring in 2005 on the 

Snake River Plain also documented 

residential and commercial 

development occurring within 0.31 mi 

(500 m) of 17 transects, and agricultural 

development was documented adjacent 

to 10 transects (Colket 2005b, Table 2). 

Currently, the effects from 

development to Lepidium papilliferum 

are confined geographically to the Snake 

River Plain, however these threats are 

not significant. Development does not 

appear to be a threat at all for L. 

papilliferum EOs on the Owyhee 

Plateau. 

Nonnative Seeded Species 

A decline in habitat quality for 

Lepidium papilliferum since 1998 in 

terms of decreased vascular plant cover, 

species richness, and species diversity 

was noted by Menke and Kaye (2006b, 

p. 19), although they found no change 

in the cover of exotic grasses or forbs in 

the plant community between 1998 and 

2004, and no relationship between 

short-term abundance of L. papilliferum 

and weedy species cover in slickspots 

(Menke and Kaye 2006b, p. 15). At this 

time, we have no data supporting a 

conclusion that longer-term abundance 

will be negatively affected by the 

presence of exotic grasses. 

Rangeland revegetation priorities on 

public lands in southeast Idaho have 

included providing forage for livestock, 

erosion control, wildfire prevention, 

reducing nonnative annual grass 

density, and watershed rehabilitation. 

Some nonnative perennials can outcompete native species and decrease 

biodiversity (summarized by Harrison et 

al. 1996, 62 pp.). For example, crested 

wheatgrass, a forage species that was 

once commonly planted within the 

range of Lepidium papilliferum, is a 

competitor and its seedlings are better 

than some native species at acquiring 

moisture at low temperatures (Lesica 

and DeLuca 1998, p. 1; Pyke and Archer 

1991, p. 4; Bunting et al. 2003, p. 82). 

The results from surveys conducted on 

the Owyhee Plateau by (Popovich 2002, 

p. 16) indicated that the number of L. 

papilliferum plants per site was lower in 

habitat with crested wheatgrass 

seedings, compared to native sagebrushsteppe habitat areas or burned areas that 

had not been seeded (Popovich 2002, p. 

16). Forage kochia (Bassia prostrata, 

formerly Kochia prostrata) is another 

nonnative species that has been used for 

rangeland habitat restoration. 

Thousands of forage kochia plants have 

been observed in relatively small 

slickspots, and it is documented as a 

direct competitor with L. papilliferum 

in slickspots (DeBolt 2002; Quinney 

2005). In one study area within the Poen 

fire rehabilitation project, post-wildfire 

monitoring over a 6-year period 

following aerial seeding with forage 


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kochia showed eventual loss of L. 

papilliferum along the monitoring 

transect, and a dramatic increase in 

forage kochia (DeBolt 2002). Four other 

slickspots, containing a total of 31 

individual L. papilliferum plants and 

numerous forage kochia plants in 2000, 

were void of L. papilliferum and 

dominated by forage kochia in 2005 

(Quinney 2005). Blue flax (Linum 

lewisii) is another nonnative seeded 

plant that was found within HIP 

transects (Colket 2005a, p. 6). It is not 

clear why these L. papilliferum plants 

were absent. 

Nonnative seeded species exist in 23 

of the 75 EOs with documented habitat 

information (17 of 60 on the Snake River 

Plain and 6 of 15 on the Owyhee 

Plateau), and 18 (14 on the Snake River 

Plain and 4 on the Owyhee Plateau) 

have non-native seeded species adjacent 

to the EO within 0.31 mi (500 m). 

The effects of invasive, nonnative 

seeded plants are monitored as parts of 

HIP range-wide transect monitoring for 

Lepidium papilliferum. In 2004, 71 L. 

papilliferum HIP transects (49 on the 

Snake River Plain and 22 on the 

Owyhee Plateau) were measured (Colket 

2005a, pp. 46 to 47). Results indicate 

that 11 transects within the Snake River 

Plain and 13 transects within the 

Owyhee Plateau had introduced 

perennial plant cover (nonnative, 

seeded species) (Colket 2005a, pp. 46 to 

47). In general, the documented high 

percentage of plant cover in the 2004 

HIP transect monitoring is attributable 

to crested wheatgrass, except at the site 

with the highest percent cover. This site 

in the Snake River Plain contained 26.8 

percent cover in forage kochia (Colket 

2005a, pp. 17, 32). Approximately 80 

percent (9,163 ac (3,708 ha)) of the 

Juniper Butte Range is dominated by 

nonnative perennial plant communities 

as a result of wildfire rehabilitation 

efforts (U.S. Air Force 1998, pp. 31–120 

to 3–121). 

Although the use of native plant 

species for wildfire rehabilitation is 

preferable, previously there have been 

problems with the availability and high 

cost of native seed (Jirik 1999, p. 110; 

Brooks and Pyke 2001, p. 9). In recent 

years, with an increase in research and 

agencies (e.g., BLM) investing heavily in 

projects such as the Great Basin Native 

Plant Selection and Increase Project and 

the Great Basin Restoration Initiative, 

native seeds and plants are more 

available to use in restoration of 

sagebrush-steppe habitat. However, 

restoration of sagebrush-steppe habitat, 

and Lepidium papilliferum habitat in 

particular, is still considered a difficult 

and expensive task. 

Under current policies, BLM no 

longer uses forage kochia as a wildfire 

rehabilitation species in Lepidium 

papilliferum habitat (USBLM 2002). 

BLM emphasizes the use of native 

plants, including forbs, in seed mixes 

and avoids the use of invasive, 

nonnative species (State of Idaho et al. 

2006, p. 26). In January 2004, BLM 

issued an Instruction Memorandum to 

employees on compliance with CCA 

requirements for emergency 

stabilization and wildfire rehabilitation 

activities (State of Idaho et al. 2006, p. 

71). 

The military has a number of ongoing 

efforts to address invasive nonnative, 

seeded plants. These efforts are 

implemented and effective in reducing 

this threat. The U.S. Air Force uses only 

non-invasive plant materials and will 

not use forage kochia, intermediate 

wheatgrass (Thinopyrum intermedium, 

formerly Agropyron intermedium), or 

salt-tolerant species such as four-wing 

saltbush (Atriplex canescens) in 

revegetation efforts, with native plants 

being used to the maximum extent 

practicable and in concert with the 

military mission for rehabilitation 

efforts (U.S. Air Force 2004, p. R–4). 

The IDARNG INRMP for the OTA 

includes the objectives for maintenance; 

where possible, improvement of 

Lepidium papilliferum habitat; and 

restoration of areas damaged by 

wildfire, through native species and 

broadcast seeding, collecting, and 

planting small amounts of native seed 

not commercially available, and 

monitoring the success of seeding efforts 

(IDARNG 2004, p. 72 to 73). Since 1991, 

the IDARNG has examined historical 

records and has seeded areas back to the 

native vegetation that was present prior 

to past wildfires. Care is taken to ensure 

that restoration does not damage L. 

papilliferum or its habitat, or introduce 

species into the habitat that were not 

present in presettlement times (IDARNG 

2004, p. 73). 

The IDARNG has demonstrated that 

diligent efforts to suppress wildfire, the 

use of native species, and minimal 

ground-disturbing wildfire 

rehabilitation activities can be effective 

in reducing the wildfire threat and rates 

at which nonnative species spread. 

Because of limited rainfall and harsh 

conditions, restoration is a difficult task 

and often requires repeated seedings on 

the OTA (IDARNG 2004, p.73). Methods 

currently used by the IDARNG may not 

be economically feasible for 

revegetation of large areas of damaged 

habitat found in other parts of the range 

of the species. 

Menke and Kaye (2006b, p. 19) 

evaluated rangewide data from 1998–

2004 and found a decline in the quality 

of habitat surrounding slickspots 

occupied with Lepidium papilliferum in 

terms of decreased vascular plant cover, 

species richness, and species diversity. 

They found no change in the cover of 

exotic grasses or forbs in the plant 

community between 1998 and 2004, and 

no relationship between short-term 

abundance of L. papilliferum and weedy 

species cover in slickspots (Menke and 

Kaye 2006b, p. 15). Because abundance 

cannot be correlated with habitat 

changes, we find that a decline in 

habitat quality is not threatening the 

species. 

Wildfire Management and Post-Wildfire 

Rehabilitation 

Activities associated with wildfire 

management include fuel management 

projects (e.g., greenstrips, prescribed 

fire), wildfire suppression activities, and 

post-wildfire rehabilitation. These 

activities can potentially impact existing 

Lepidium papilliferum occurrences and 

damage slickspot habitat (ILPG 1999) by 

the establishment of nonnatives or by 

mechanical disturbances. 

Drill seeding is a rehabilitation 

technique that is used after wildfire. 

Drill seeding uses a rangeland drill that 

plants and covers seed simultaneously 

in furrows. It is designed to give the 

seeds moisture and temperature 

advantages that will enhance their 

competitive fitness and, consequently, 

their success rate (Scholten and Bunting 

2001, p. 3). Drill seeding has been used 

on wildfire rehabilitation projects on 

BLM lands where Lepidium 

papilliferum occurs. It impacts 

slickspots through mechanical 

disturbance and introduces other, often 

nonnative, plant materials. Historically, 

slickspots were not understood to have 

any special ecological value, and so no 

attempt was made to avoid them during 

rehabilitation activities. We have no 

data on the extent that drill seeding may 

still be affecting L. papilliferum habitat, 

although some habitat areas have buffers 

established to protect them. 

Disk or drill seeding has occurred on 

14 of 60 EOs on the Snake River Plain 

and 10 of 15 EOs on the Owyhee Plateau 

(Colket et al. 2006, Appendix C). Drill 

seeding may have less severe impacts on 

slickspot habitat than disking the soil, 

but the success of restoring slickspots 

and Lepidium papilliferum plants varies 

considerably. The benefits of post-fire 

revegetation, and subsequent recovery 

of soil surfaces conducive to 

germination and establishment of native 

perennial grass and shrub communities, 

may outweigh the initial short-term 

disturbance associated with drill 


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seeding (Young and Allen 1996, pp. 533 

to 534; Bunting et al. 2003, pp. 82 to 85). 

Ground disturbance associated with 

wildfire control, such as establishment 

of fire lines (areas with vegetation 

removed to break fuel continuity), fire 

camps, and staging areas, and the use of 

wildfire suppression vehicles, can also 

impact existing Lepidium papilliferum 

occurrences and damage slickspot 

habitat (ILPG 1999). Similarly, 

construction of fuel breaks, while 

beneficial in slowing the movement of 

wildfire, may also impact L. 

papilliferum through ground 

disturbance or the use of invasive, 

nonnative, seeded species. Only two 

EOs, both on the Snake River Plain, are 

documented as having wildfire lines 

within them, although neither has 

documented wildfire lines within 

slickspots (Colket et al. 2006, Appendix 

C). Herbicides used to pretreat 

rehabilitation areas prior to seeding may 

also impact L. papilliferum. These 

activities may injure or kill individual 

plants or the seed bank through 

mechanical disturbance or direct 

exposure to herbicides. Indirect effects 

associated with mechanical disturbance 

of slickspot soils include increased 

probability of establishment of invasive, 

nonnative plants, burying of the seed 

bank to a depth where seedlings cannot 

emerge from the soil, and mixing of 

slickspot soil layers, which affects the 

suitability of a microsite for the species. 

The effect of drill seeding is 

monitored as part of the HIP range-wide 

transect monitoring. In 2004, of the 71 

Lepidium papilliferum transects 

monitored, 3 transects on the Snake 

River Plain and 5 transects on the 

Owyhee Plateau had evidence of old 

drill seedings within slickspots; no 

transects had evidence of firefighting 

disturbances within slickspots (Colket 

2005a, pp. 44 to 45). 

Through the CCA, BLM has 

implemented a number of conservation 

measures to avoid or minimize impacts 

to the species from wildfire prevention, 

wildfire suppression, and post-wildfire 

emergency rehabilitation activities. 

These measures are effective to reduce 

this threat at least partially. BLM and 

fire cooperators distribute maps and 

inform crew members of the location of 

Lepidium papilliferum to maximize 

wildfire protection in those areas, and to 

minimize potential impacts from 

suppression related activities (State of 

Idaho et al. 2006, p. 26). Per 

conservation measure .08 of the CCA, 

BLM uses seeding techniques that 

minimize soil disturbance, such as notill drills and rangeland drills equipped 

with depth bands, when rehabilitation 

and restoration projects have the 

potential to impact occupied or suitable 

habitat (State of Idaho et al. 2006, p. 26). 

Rehabilitation and restoration standard 

operating procedures for L. papilliferum 

were issued in an Instruction 

Memorandum in January 2004 (State of 

Idaho et al. 2005, p. 33). BLM avoids 

spraying herbicides within or near 

known occupied habitat, and conducts 

pretreatment surveys of at least 5 

percent of previously unsurveyed 

habitat prior to herbicide or ground 

disturbing treatments associated with 

emergency wildfire rehabilitation 

activities (State of Idaho et al. 2006, p. 

27). 

The military has a number of ongoing, 

effective efforts to address wildfire 

management activities. The potential for 

wildfire ignition and spread are 

decreased by the placement of 

appropriate restrictions on activities, 

and the use of wildfire indices to restrict 

activities when the wildfire rating 

hazard is extreme (U.S. Air Force 2004, 

p. R–3). The U.S. Air Force uses drill 

seeders equipped with depth bands to 

avoid unnecessary disturbance to soils, 

avoids slickspots to the maximum 

extent practicable in drill seeding 

efforts, and uses broadcast seeding to 

the maximum extent practicable 

consistent with reseeding goals (U.S. Air 

Force 2004, p. R–4). The IDARNG 

restores wildfire-damaged areas using 

native species and broadcast seeding. 

Similarly, the IDARNG provides their 

fire crews with maps of all known 

occupied habitat, and actively 

suppresses all wildfires on the OTA. 

Blading is not permitted in Lepidium 

papilliferum habitat areas on the OTA. 

Existing roadways serve as fuel breaks 

within the OTA, and allow for quick 

access for wildfire management 

(IDARNG 2004, p. 73). Since 1987, the 

IDARNG has demonstrated that efforts 

to suppress wildfire and the use of 

native species with minimal grounddisturbing fire rehabilitation activities 

can be effective in reducing the wildfire 

threat and reducing establishment rates 

of nonnative, unseeded species 

associated with wildfire management 

activities (IDARNG 2004, p. 73). 

Wildfire management has positive 

consequences (i.e., the control of 

wildfires) and potentially negative 

consequences (i.e., destruction of 

slickspots through habitat restoration 

and wildfire control practices), 

depending on how the activity is 

implemented. The Expert Panel 

considered wildfire management to be 

less of an impact than the first four 

factors discussed above. After our 

review of the available data, we have 

determined that wildfire management 

can potentially impact Lepidium 

papilliferum, although this activity is 

not threatening the species. 

Recreation 

Recreational activities that may affect 

Lepidium papilliferum include hiking, 

horseback riding, and off-highway 

vehicles. Juniper Butte Range and areas 

of the OTA are protected from 

recreational activities because of 

military restrictions. 

Off-highway vehicle use has been 

documented in 16 of the 75 EOs (16 of 

60 on the Snake River Plain, none on 

the Owyhee Plateau) for which habitat 

information has been collected (Colket 

et al. 2006, Appendix C). 

Effects from recreational activities are 

monitored as part of the HIP range-wide 

transect monitoring for Lepidium 

papilliferum. In 2004, 3 of 49 transects 

on the Snake River Plain showed offhighway vehicle tracks within the EO 

area, and 1 transect had off-highway 

vehicle tracks directly through it (Colket 

2005b, Table 1). In 2005, two EOs on the 

Snake River Plan had tracks in the 

general occurrence area, and one had 

tractor tracks running through the 

transect (Colket 2005b, Table 1). New 

tracks are documented each year, so 

monitoring reports are not cumulative. 

Off-highway vehicle use was also 

monitored within the Owyhee Plateau L. 

papilliferum EOs in 2004 and 2005, but 

no off-highway use was documented. 

An analysis of HII transects between 

1998 and 2001 indicated that only a few 

transects had OHV use in each year, that 

impacts appeared to be minimal, and 

that OHV use regionally does not appear 

to be a major agent of habitat 

degradation, while noting that 

concentrated OHV use in localized areas 

could potentially be more problematic 

(Menke and Kaye 2006a, p. 18). 

Therefore, we have determined from the 

available data that any potential impact 

to Lepidium papilliferum from 

recreation appears to be localized. 

Additionally, we have no data 

indicating that recreation is a major 

agent of habitat degradation and 

therefore is not threatening the species. 

Military Training 

Military activities within the range of 

Lepidium papilliferum include 

ordnance impact areas, training 

activities, military development, and an 

increased risk of wildfire and nonnative 

plant invasions. Military training occurs 

on the Snake River Plain at the OTA 

(seven EOs) and on the Owyhee Plateau 

at the Juniper Butte Range (a portion of 

one EO). INRMPs developed for both the 

Juniper Butte Range and the OTA 

provide management direction reducing 

or eliminating many of these threats 


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from military training exercises. The 

OTA, where 14 years of INRMP 

conservation efforts have been 

implemented, is considered the most 

intact, native L. papilliferum habitat 

range-wide (Colket et al. 2006, pp. 22 to 

23; Meyer 2005, p. 1). 

The IDARNG and the U.S. Air Force 

are implementing various conservation 

efforts to avoid or reduce adverse effects 

of military training on the species and 

its habitat, and the IDARNG has had 

measures in place that promote the 

conservation of Lepidium papilliferum 

prior to revisions to the IDARNG INRMP 

made in 2004. The threat of military 

training is localized in area, and 

minimal in significance across the range 

of the species. 

Summary of Factor A 

There is little disagreement that the 

quality and composition of the sagebrush steppe ecosystems that surrounds 

the slickspot microsites inhabited by 

Lepidium papilliferum has become 

degraded over time. Increased fire 

frequencies largely caused by the 

invasion of exotic annual grasses are of 

particular concern, as are potentially 

destructive penetrating trampling events 

of slickspots by livestock. What is not 

clear is the relationship between these 

factors and the long-term persistence or 

viability of L. papilliferum. What little 

data we have at this time does not 

indicate any direct relationship between 

the abundance of L. papilliferum and 

factors such as livestock use and weedy 

species cover. Burning appears to have 

a negative impact on slickspot 

conditions, such as increasing exotic 

species cover and decreasing soil crust 

cover, but these factors were not 

significantly correlated with L. 

papilliferum abundance. Accordingly 

we find that L. papilliferum is not 

threatened by habitat changes to the 

extent that protection under the Act is 

needed. 

B. Overutilization for Commercial, 

Recreational, Scientific, or Educational 

Purposes 

We have no data indicating that 

overutilization for commercial, 

recreational, scientific, or educational 

purposes is a threat to Lepidium 

papilliferum. 

C. Disease or Predation 

Herbivory of Lepidium papilliferum is 

reported as sparse. Herbivory by rodents 

and insects has been occasionally 

observed on L. papilliferum plants. In 

one instance, grasshoppers (possibly 

Acrididae) were observed consuming L. 

papilliferum flower petals (Geertson 

2004, p. 3). We are unaware of any 

specific studies documenting foraging 

on L. papilliferum by Mormon crickets 

(Anabrus simplex). Insect herbivores 

have been studied as part of pollinator 

and reproductive biology studies 

(Robertson et al. 2004). Flower petal 

herbivory of L. papilliferum by 

chrysomelid beetles (Phyllotreta spp.) 

was shown to be detrimental to seed 

production because of decreased 

pollinator visitation; pollinators did not 

visit flowers with missing flower petals. 

Other insect herbivores include 

plutellid moth larvae, which eat all 

portions of the plant; harvester ants 

which eat entire fruits or leaves from 

plants; mirid bugs, which probably suck 

phloem; grasshoppers (Acrididae); and 

leafhoppers (Cicadellidae), which 

probably suck phloem (Robertson et al. 

2004, p. 12). At three different sites (one 

at Kuna Butte and two at the Orchard 

Training Area), 35 percent, 37 percent, 

and 23 percent of plants showed 

evidence of insect herbivore damage 

(Robertson et al. 2004). 

Herbivory impacts to L. papilliferum 

from large, native ungulates, such as elk, 

deer and antelope, have not been 

observed. However, pronghorn antelope 

tracks and droppings (U.S. Air Force 

2003, p. 14) and elk tracks and 

droppings (State of Idaho et al. 2006, 

Appendix A) have been infrequently 

documented in slickspots that support 

L. papilliferum. Domestic sheep have 

been observed pulling the plants from 

the ground and spitting them out 

(Quinney and Weaver 1998). Herbivory 

by cattle has not been observed. 

We have no data to support the 

conclusion that disease or predation are 

a significant threat to Lepidium 

papilliferum. 

D. Inadequacy of Existing Regulatory 

Mechanisms 

Lepidium papilliferum is considered a 

sensitive species by BLM (BLM 2003, p. 

2–1). BLM has regulations that address 

the need to protect sensitive, candidate, 

and federally listed species, and BLM 

has initiated monitoring of L. 

papilliferum on Federal lands. 

Monitoring can be used to identify 

threats, which can result in management 

actions necessary for controlling L. 

papilliferum habitat degradation. 

As a signatory of the CCA (State of 

Idaho et al. 2003, 2006), BLM is the 

primary land management agency 

implementing conservation efforts for 

this species. The majority of 

implemented conservation efforts 

associated with the CCA occur on BLM 

lands. In recent years, BLM has initiated 

efforts to conserve the species, and the 

CCA represents a major commitment by 

BLM for management of lands that 

account for a majority of the range of the 

species (87 percent of the total area and 

portions of 71 of the 85 extant EOs). 

Conservation efforts are not a basis for 

our finding here, but ongoing 

conservation efforts will be helpful in 

offsetting any effects that do occur from 

potential threats, and further voluntary 

conservation efforts are encouraged. 

Therefore, available data does not 

suggest that existing regulatory 

mechanisms are inadequate. 

E. Other Natural or Manmade Factors 

Affecting Its Continued Existence 

The Expert Panel identified 

unpredictable rain events and drought 

as climate factors affecting Lepidium 

papilliferum, but did not consider them 

to be significant threats to the species. 

We have no data that climatic patterns 

of rainfall will significantly change over 

time. Therefore, we do not consider 

drought or lack of rainfall to pose an 

extinction risk, although it can cause a 

short-term decline in population 

numbers. No other threats to L. 

papilliferum were identified under 

Factor E. 

Summary of Factors Affecting the 

Species—Conclusion 

The primary factors affecting 

Lepidium papilliferum are habitat 

based. We examined other potential 

threats and determined that the 

available data does not suggest that the 

other factors are threatening the species. 

We examined data available for effects 

of wildfire frequency, invasive 

nonnative plants (especially annual 

grasses), livestock impacts, and 

residential and agricultural 

development. While disturbances to L. 

papilliferum can result from wildfire, 

commercial and residential 

development, livestock use, and grounddisturbing wildfire management 

practices or recreation activities the 

available data did not support a finding 

that the species is threatened by one or 

more of these potential threats. Our 

analysis of the factors affecting the 

species indicates that there is cause for 

concern regarding the decline in quality 

of the sagebrush-steppe ecosystem and 

the slickspot microhabits within. We 

examined the increased frequency of 

fires, fueled largely by invasive exotic 

annual grasses, and how it is altering 

the diversity and composition of the 

native plant community. We found that 

there was no evidence that habitat 

degradation is a threat to the species 

such that listing is warranted at this 

time. However, the concerns generated 

by our analysis emphasize the need for 

further research and support for ongoing 

efforts to restore and manage the 


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sagebrush steppe ecosystem. This also 

underscores the necessity for close 

monitoring of L. papilliferum and other 

components of the sagebrush 

community to better determine the 

response of these species to the 

alteration of their environment. The best 

available data do not demonstrate any 

relationship between altered habitat 

conditions and the status of L. 

papilliferum. The limited data available 

do not demonstrate any significant 

relationship between the abundance of 

L. papilliferum and factors such as 

livestock use or weedy species cover. 

The two available datasets of abundance 

monitoring present conflicting results 

regarding the trend of the population 

over time. The population of L. 

papilliferum is positively correlated 

with spring precipitation. L. 

papilliferum evolved in an arid 

environment and has adapted to 

fluctuations in precipitation. We have 

no data demonstrating that precipitation 

levels are varying significantly from 

historical patterns. Accordingly, we do 

not find that fluctuation in precipitation 

is a threat to the species. 

Status Review Process 

Section 4(b)(1)(A) of the Act requires 

us to consider the best scientific and 

commercial data available, as well as 

efforts being made by States or other 

entities to protect a species, when 

making a listing decision. To meet this 

standard, we systematically collected 

information on Lepidium papilliferum, 

its habitats, and environmental factors 

affecting the species from a wide array 

of sources. In addition, we received a 

substantial amount of unpublished 

information from other Federal 

agencies, States, private industry, and 

individuals. We solicited information 

on all Federal, State, or local 

conservation efforts currently in 

operation or planned for either L. 

papilliferum or its habitat. 

In addition, we convened an Expert 

Panel of seven independent scientists 

who assisted in evaluating the available 

data and discussed threats to L. 

papilliferum. Expert Panels are not a 

required component of our analysis, but 

are used occasionally by the Service to 

help inform decision makers when there 

is uncertainty. Scientific information on 

Lepidium papilliferum and associated 

habitat is limited; data gaps and 

uncertainty exist in the scientific 

community’s knowledge of threats that 

may affect L. papilliferum populations 

across its geographical range of 

sagebrush-steppe habitat. For these 

reasons, we requested input from 

scientific experts to help us assess the 

status of L. papilliferum. The Expert 

Panel consisted of experts in the fields 

of small populations/fragmentation, 

annual desert plants, sagebrush 

community ecology, wildfire/nonnative 

species, soils and livestock use, and L. 

papilliferum. The discussion of the 

Expert Panel, and other available data, 

was then considered by our Manager 

Panel in order to develop the decision 

reported in this finding. 

We conducted three phases of 

information synthesis and evaluation. 

First, the information on individual 

planned conservation efforts was 

evaluated to determine which of the 

efforts that have not yet been 

implemented, or have been 

implemented but have not yet 

demonstrated whether they are 

effective, met the standard for sufficient 

certainty of implementation and 

effectiveness in the Policy for 

Evaluating Conservation Efforts (68 FR 

15115, March 28, 2003). Second, we 

employed the assistance of an Expert 

Panel that evaluated all factors possibly 

affecting the species’ current status. 

Subsequent to the work done by the 

expert panel new information became 

available. Our Manager Panel evaluated 

all the information, including the new 

information, on status, trends, ongoing 

conservation efforts, and potential risk 

to determine whether the species should 

be listed as threatened, listed as 

endangered, or not warranted for listing. 

We structured these three phases by 

differentiating two distinct stages of the 

analysis: (1) A risk analysis phase that 

included compiling biological 

information and estimating the risk to 

the species; and (2) a risk management 

phase where our Manager Panel 

evaluated whether the potential threats 

identified as part of our section 4(a)(1) 

analysis, and summarized in this 

finding, qualify Lepidium papilliferum 

as a threatened or endangered species 

under the Act. 

Policy for Evaluation of Conservation 

Efforts 

PECE provides a framework and 

criteria for evaluating conservation 

efforts that have not been implemented 

or have not demonstrated whether they 

are effective at the time of a listing 

decision. Recognizing that the certainty 

of implementation and effectiveness of 

various planned efforts within a 

conservation plan, strategy, or 

agreement may vary, PECE requires that 

we evaluate each individual 

conservation effort that has not been 

implemented or for which effectiveness 

has not been demonstrated, and the 

policy provides criteria to direct our 

analysis. PECE specifies that to consider 

that a conservation effort(s) contributes 

to forming a basis for not listing a 

species or listing a species as threatened 

rather than endangered, we must find 

that the conservation effort is 

sufficiently certain to be implemented 

and effective so as to have contributed 

to the elimination or adequate reduction 

of one or more threats to the species 

identified through the section 4(a)(1) 

analysis. (68 FR 15115, March 28, 2003). 

Thus, PECE is relevant in situations 

where a threats analysis, conducted 

without consideration of conservation 

efforts that meet the standard in PECE, 

indicates that listing is warranted. In 

such situations, we then consider the 

effect of conservation efforts that meet 

the ‘‘sufficient certainty’’ standard in 

PECE to determine whether such efforts 

have contributed to the elimination or 

adequate reduction of threats, leading to 

a determination that the species does 

not meet the definition of threatened or 

endangered and therefore does not 

warrant listing, or that that listing as 

threatened, rather than endangered, is 

appropriate. 

Because of the time needed to 

evaluate large numbers of individual 

conservation efforts under PECE, it 

sometimes is necessary to proceed with 

the evaluation process prior to 

completing the threats analysis pursuant 

to section 4(a)(1) of the Act, i.e., before 

we have determined whether efforts that 

meet the standard in PECE will actually 

play a role in our determination. That 

was the case in this situation. 

For the PECE analysis, we reviewed 

activities identified in five plans or 

conservation strategies. The five plans 

were: (1) The Candidate Conservation 

Agreement for Slickspot Peppergrass; (2) 

the Idaho Army National Guard 

Integrated Natural Resource 

Management Plan for Gowen Field/ 

Orchard Training Area; (3) the U.S. Air 

Force Integrated Natural Resource 

Management Plan for Mountain Home 

Air Force Base; (4) the Conservation 

Agreement by and between Boise City 

and the U.S. Fish and Wildlife Service 

for Allium aasea (Aase’s onion), 

Astragalus mulfordiae (Mulford’s 

milkvetch), and Lepidium papilliferum 

(slickspot peppergrass); and (5) the 

Conservation Agreement for Slickspot 

Peppergrass (Lepidium papilliferum) at 

the Boise Airport, Ada County, Idaho. 

We reviewed each conservation effort 

contained in the five conservation plans 

to determine which had been 

implemented and demonstrated 

effectiveness in reducing one or more 

threats. We relied on available 

documentation to determine if the effort 

was implemented by the time of our 

analysis. As explained above, 

conservation efforts that have been 


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implemented and demonstrated 

effectiveness are not subject to 

evaluation under PECE, and are 

considered as part of the section 4(a)(1) 

threats analysis (below). We also used 

the criteria in PECE to evaluate efforts 

that had not been implemented, and 

efforts that had been implemented but 

had not yet demonstrated whether they 

were effective. We did not rely on those 

efforts that met the PECE standard in 

our determination. We made our 

determination on the basis of the threats 

analysis and information about 

population status and trends (see 

below). However, we consider the 

conservation plans and the continued 

commitment of stakeholders to 

implement the conservation efforts 

important to the long-term sustainability 

of Lepidium papilliferum. 

Expert Panel 

In May 2006, we convened a panel 

composed of seven experts to provide 

assistance in understanding the ecology 

and biology of Lepidium papilliferum, 

to assess the threats and extinction risk 

to the species, and to identify areas of 

scientific uncertainty. The panelists 

brought a variety of expertise to the 

discussion, including knowledge and 

experience with wildfire, nonnative 

species, range and grazing issues, soils, 

small populations and fragmentation, 

annual desert plants, and sagebrush 

community ecology, and included a L. 

papilliferum species expert. 

The top two potential threats 

identified by the Expert Panel were the 

invasion of cheatgrass and the 

subsequent changes to the fire regime in 

the sagebrush-steppe ecosystem. Several 

members of the panel agreed that the 

expansion of cheatgrass will likely 

create annual grasslands that will 

dominate the Snake River Plain within 

the next 50 years, and would impact 

Lepidium papilliferum and its habitat. 

The invasion of exotic annual grasses in 

turn increases the frequency of fire, 

leading to further alterations of the 

native plant community. 

Following the May 2006 Expert Panel, 

the Service received additional 

information including new analysis of 

Lepidium papiliferum population and 

habitat monitoring data (e.g., Menke and 

Kaye 2006b). This information was not 

available to the expert panel and did not 

factor into their extinction risk 

estimates. The Service considers the 

extinction risk estimates by the expert 

panel to be informative in that they 

provide a context in which we were able 

to assess the new information. However, 

the estimates have limited applicability 

to our determination in light of this new 

information. In particular, the new 

information limits the Service’s 

confidence in extrapolation of L. 

papilliferum population trends at the 

OTA to population trends in the 

remaining Snake River Plain 

metapopulation and the range-wide 

population. 

Manager Panel 

Our Manager Panel reviewed 

background materials, interacted with 

the Expert Panel during their exercises, 

and participated in discussions about 

the application of the Act and specific 

terms contained in the Act. The 

managers based their assessments on the 

data in the record, including comments 

previously received; the data presented 

by the individual members of the Expert 

Panel, as well as data received 

subsequent to the Expert Panel process; 

known information gaps and 

uncertainty; the number and severity of 

the threats affecting the species; and 

mitigating circumstances that might 

ameliorate one or more of the threats. 

The Manager Panel convened on three 

occasions. This rule is based on the 

record of these discussions and all 

relevant and available information 

pertaining to the threats to and status of 

the species. 

Determination 

We examined the data regarding L. 

papilliferum populations and 

occurrence as well as the specific 

habitat needs of the species. We 

included an examination of habitat 

degradation and modification to the 

sagebrush-steppe ecosystem and the 

slickspot microhabitats from the current 

wildfire regime (i.e., increasing 

frequency, size, and duration), invasion 

of non-native weed species (e.g., 

cheatgrass), effects of livestock use (e.g., 

penetrating trampling, disruption of soil 

crust covers), and residential and 

agricultural development to determine 

whether there were any resulting effects 

on L. papilliferum.While the sagebrush 

steppe-ecosystem has experienced 

decreased native shrub cover and 

increased exotic grass cover, we have no 

data demonstrating that these factors 

affect L. papilliferum populations. Data 

at this point are limited and based on 

observational measures rather than 

controlled experiments, but indicate no 

significant relationship between the 

abundance of L. papilliferum and factors 

such as livestock use or weedy species 

cover in slickspots. The data limitations 

point to the value of the conservation 

activities and collection of data and to 

improve our understanding of the 

species, as well as preventive actions. 

However, we do not have evidence that 

the factors evaluated here have led to a 

negative population trend range-wide in 

L. papilliferum. 

Determining range-wide abundance 

and population trends of Lepidium 

papilliferum is complicated by its 

annual and biennial life histories and its 

correlation to spring precipitation, 

which can vary widely from year to 

year. Spring rainfall patterns also vary at 

the local scale, which can influence 

abundance of the plant from one 

population to another in the same local 

area. Abundance estimates are 

confounded because seeds can remain 

dormant (and viable) in the seed bank 

for at least 12 years. All of these factors 

lead to great natural variability in the 

abundance of L. papilliferum from year 

to year, which confounds our 

assessment of population trends. 

Currently we have two relatively longterm datasets of abundance monitoring 

for Lepidium papilliferum on which to 

base our evaluation of population trends 

for this species, the data from the OTA 

and the data from range-wide HII and 

HIP monitoring (which includes several 

transects on the OTA). The dataset from 

the OTA indicates recent declines in the 

abundance of the species that do not 

correlate as expected with patterns of 

spring precipitation, beginning in 2003 

(Weaver 2006, pp. 1–6). Data from the 

range-wide HII and HIP transects 

demonstrate that although the 

population declined following one of its 

highest recorded peaks in abundance in 

1998 (the first year for which HII data 

was available), the range-wide 

population then stabilized and began 

increasing after 2003 (Menke and Kaye 

2006b, Figure 3; USFWS 2006f, Figures 

8, 9). The range-wide data show 

increases in populations since 2003, and 

populations have continued to show a 

positive relationship to spring 

precipitation. The available data are not 

consistent with regard to an overall 

population trend for L. papilliferum. 

The data from OTA indicate that plant 

abundance declined after 1995 and was 

generally correlating with spring 

precipitation until 2003 through present 

when plant abundance did not increase 

with higher levels of spring 

precipitation. Range-wide data indicate 

that L. papilliferum abundance has 

correlated with spring precipitation and 

abundance of the plant range-wide has 

increased since 2004 to levels 

comparable to 1998 range-wide data. We 

consider this range-wide data to be the 

best available at this time. 

Identification of data gaps and 

uncertainties helps explain the limits of 

our understanding of future risk to 

Lepidium papilliferum. We are required 

to make a determination whether the 

species qualifies as threatened or 


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1644 Federal Register / Vol. 72, No. 8 / Friday, January 12, 2007 / Proposed Rules 

endangered under the Act based solely 

on the best available scientific and 

commercial data. To ensure that we 

considered this data in the proper 

context, the Manager Panel (see Status 

Review Process) participated in a 

structured analysis that included an 

evaluation of the Act’s statutory 

requirements, in particular the Act’s 

definitions of threatened and 

endangered, and a review of the data 

from the risk analysis and all other 

compiled biological information. They 

considered the data about risks to L. 

papilliferum, including explicit 

measures of uncertainty, and the data 

supporting the existence of those risks, 

in the context of the requirements of the 

Act. The definitions in the Act include: 

an endangered species is in danger of 

extinction throughout all or a significant 

portion of its range, and a threatened 

species is likely to become an 

endangered species within the 

foreseeable future throughout all or a 

significant portion of its range (16 

U.S.C. 1532(6), (20)). 

The Manager Panel convened on three 

occasions: once during the science 

panel and shortly after the science panel 

in May 2006, and again in November 

2006. 

When the Manager Panel convened in 

November 2006, focal points of 

discussion included results of the 

Menke and Kaye 2006 report that was 

not available at the time of the science 

panel and new insights gained from 

public comment and review of 

monitoring results. Of particular note 

were the results that spring 

precipitation (March–May) explained 89 

percent of the variation in plant 

abundance for the years 1998–2001, 

2002, and 2004 sampled by range-wide 

HII and HIP transects (Menke and Kaye 

2006b, p. 10). In addition, this report 

demonstrated a consistent correlation 

between the abundance of Lepidium 

papilliferum and spring rainfall 

throughout all years and reported 

population increases range-wide since 

2003, which contradicted trends 

reported based on data from the OTA. 

Upon reviewing the studies and plant 

abundance data, the Manager Panel 

concluded that indications of declines 

in plant abundance at OTA cannot be 

reasonably extrapolated to the rangewide population of Lepidium 

papilliferum, and that the conflicting 

data indicating range-wide population 

increases in recent years from the HII 

and HIP transects add additional 

uncertainty to our ability to assess the 

nature of any population trend for L. 

papilliferum. The high variability in 

plant numbers from year to year, 

expected for an ephemeral annual plant 

with a dormant seed bank that is highly 

dependent on seasonal rainfall, 

increases the difficulty of discerning 

any trend in abundance data over time. 

Although the quality of the sagebrushsteppe slickspot habitat of L. 

papilliferum has become degraded due 

to a variety of threats, the existing data 

do not support a determination that 

those threats are affecting L. 

papilliferum across all or a significant 

portion of its range sufficient to require 

the protections of the Act at this time. 

The managers decided that the data 

before them did not support a 

determination that L. papilliferum is 

exhibiting a population decline. The 

available data do not lead us to 

conclude that the species is declining 

range-wide, thus we are unable to 

establish that there is a point in time 

when the species is likely to be in 

danger of extinction throughout all or a 

significant part of its range. The district 

court decision found that our previous 

analysis of foreseeable future was 

unsupported in the record. In particular, 

the court noted that the expert panel 

concluded that there was a 64–80 

percent chance that L. papilliferum 

would become extinct in the next 100 

years. Thus, the court thought that our 

ultimate conclusion that the species was 

not likely to become in danger of 

extinction in the foreseeable future 

depended upon a preliminary 

conclusion that the foreseeable future 

was in this case a period of time 

considerably less than 100 years. 

Because the court found that we had not 

adequately explained why the Service 

selected the timeperiod it did for 

foreseeable future, the court held that 

our determination was arbitrary and 

capricious. In contrast, given the new 

information, the question of how much 

of the future is foreseeable is no longer 

relevant. We conclude that apparent 

abundance of the plant can fluctuate 

widely from one year to the next, and 

abundance is strongly correlated with 

spring precipitation. We have no data 

demonstrating that precipitation levels 

are varying significantly from historical 

patterns. L. papilliferum evolved in an 

arid environment and has adapted to 

fluctuations in precipitation by a 

strategy of relatively long-term seed 

viability and by increased seed 

production during favorable conditions. 

Thus, there is no current evidence that 

threats are working to threaten the 

species with endangerment and we 

cannot predict extinction at any point in 

time in the foreseeable future, regardless 

of whether the foreseeable future is 

defined as less than 100 years, 100 

years, or more than 100 years. 

In summary, the Act requires us to 

make a decision based on the best 

available data at the time of the listing 

determination. The best available data 

for Lepidium papilliferum indicate that, 

while the broad scale habitat in which 

the species exists is degraded, we have 

no data that correlates this with species 

abundance. We know that annual 

abundance is strongly correlated with 

spring precipitation (March–May) and a 

high degree of variability in annual 

abundance is therefore to be expected. 

The best available range-wide data 

indicate that abundance of the 

population range-wide is strongly 

correlated with precipitation and has 

increased in recent years in association 

with increased rainfall, as expected. 

Accordingly based solely on the best 

available data, we find that Lepidium 

papilliferum is not presently in danger 

of extinction throughout all or a 

significant portion of its range nor is it 

likely to become an endangered species 

throughout all or a significant portion of 

its range in the foreseeable future. 

References Cited 

A complete list of all references cited 

herein, as well as others, is available 

upon request from our Snake River 

Basin Office (see ADDRESSES section). 

Author(s) 

The primary authors of this final rule 

are staff of the U.S. Fish and Wildlife 

Service. 

Authority: 16 U.S.C. 1531 et seq. 

Dated January 4, 2007. 

H. Dale Hall, 

Director, U.S. Fish and Wildlife Service. 

[FR Doc. 07–60 Filed 1–11–07; 8:45 am] 

BILLING CODE 4310–55–P 


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