52014 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

DEPARTMENT OF THE INTERIOR 

Fish and Wildlife Service 

50 CFR Part 17 

[RIN 1018-AW34] 

[FWS-R1-ES-2008-0096] 

[MO 922105-0008-B2] 

Endangered and Threatened Wildlife 

and Plants; Listing Lepidium 

papilliferum (Slickspot Peppergrass) 

as a Threatened Species Throughout 

Its Range 

AGENCY: Fish and Wildlife Service, 

Interior. 

ACTION: Final rule. 

SUMMARY: We, the U.S. Fish and 

Wildlife Service (Service), determine 

that Lepidium papilliferum (slickspot 

peppergrass), a plant species from 

southwest Idaho, is a threatened species 

under the Endangered Species Act of 

1973, as amended (Act). This final rule 

implements the Federal protections 

provided by the Act for this species. We 

have determined that critical habitat for 

L. papilliferum is prudent but not 

determinable at this time. 

DATES: This rule becomes effective 

December 7, 2009. The effective date 

has been extended to 60 days after 

publication in the Federal Register to 

allow the U.S. Bureau of Land 

Management (BLM) to finish conferring 

with the Service under section 7(a)(4) of 

the Act on the BLM’s issuance of 

grazing permits within the range of 

Lepidium papilliferum. 

ADDRESSES: This final rule is available 

on the Internet at http:// 

www.regulations.gov and also at http:// 

www.fws.gov/idaho. Comments and 

materials received, as well as supporting 

documentation used in the preparation 

of this rule, will be available for public 

inspection, by appointment, during 

normal business hours at: U.S. Fish and 

Wildlife Service, Idaho Fish and 

Wildlife Office, 1387 S. Vinnell Way, 

Room 368, Boise, ID 83709; by 

telephone at 208-378-5243; by facsimile 

at 208-378-5262. 

FOR FURTHER INFORMATION CONTACT: Jeff 

Foss, Field Supervisor, at above address, 

telephone, and facsimile, or by 

electronic mail at: 

fw1srbocomment@fws.gov. Persons who 

use a telecommunications device for the 

deaf (TDD) may call the Federal 

Information Relay Service (FIRS) at 800- 

877-8339. 

SUPPLEMENTARY INFORMATION: 

Background 

Lepidium papilliferum is a small, 

flowering plant in the mustard family 

(Brassicaceae). The plant grows in 

unique microsite habitats known as 

slickspots, which are found within the 

semiarid sagebrush-steppe ecosystem of 

southwestern Idaho. The species is 

endemic to this region, known only 

from the Snake River Plain and its 

adjacent northern foothills (an area 

approximately 90 by 25 miles (mi) (145 

by 40 kilometers (km)), or 2,250 square 

miles (mi2) (5,800 square kilometers 

(km2)), with a smaller disjunct 

population on the Owyhee Plateau (an 

area of approximately 11 by 12 mi (18 

by 19 km), or 132 mi2 (342 km2). The 

restricted distribution of L. papilliferum 

is likely due to its adaptation to the 

specific conditions within these 

slickspot habitats. The absence of all 

perennial plant species from these sites 

likewise demonstrates the specialization 

of L. papilliferum persisting in the 

unique conditions provided by 

slickspots (Fisher et al. 1996, p. 16). The 

primary threat to L. papilliferum (as 

described under The Present or 

Threatened Destruction, Modification, 

or Curtailment of Its Habitat or Range, 

below) is the present or threatened 

destruction, modification, or 

curtailment of its habitat and range due 

to the increased frequency and extent of 

wildfires under a wildfire regime 

modified and exacerbated by the spread 

of invasive nonnative plants, 

particularly nonnative annual grasses 

such as Bromus tectorum (cheatgrass). 

In addition, even under conservative 

projections of the consequences of 

future climate change, the threats posed 

by wildfire and the invasion of B. 

tectorum are expected to further 

increase within the foreseeable future. 

Other threats to the species include 

competition and displacement by 

nonnative plant species, development, 

potential seed predation by harvester 

ants, and habitat fragmentation and 

isolation of small populations. 

Previous Federal Actions 

On July 15, 2002, we proposed to list 

Lepidium papilliferum as endangered 

(67 FR 46441). On January 12, 2007, we 

published a document in the Federal 

Register withdrawing that proposed rule 

(72 FR 1622). For a description of 

Federal actions concerning L. 

papilliferum prior to the 2007 

withdrawal, please refer to that 2007 

withdrawal document. The withdrawal 

of the proposal to list L. papilliferum 

was based on our conclusion that, while 

its sagebrush-steppe matrix habitat is 

becoming increasingly degraded, the 

best available data at the time provided 

no evidence indicating that this 

degradation was impacting L. 

papilliferum within its slickspot 

microsites. Furthermore, we concluded 

that, although we found that abundance 

on the Idaho Army National Guard’s 

Orchard Training Area (OTA) had 

decreased in recent years, the observed 

rangewide fluctuations in population 

numbers appeared to be consistent with 

varying levels of spring rainfall, as 

expected. On April 6, 2007, Western 

Watersheds Project filed a lawsuit 

challenging our decision to withdraw 

the proposed rule to list L. papilliferum. 

On June 4, 2008, the U.S. District Court 

for the District of Idaho (Court) reversed 

the decision to withdraw the proposed 

rule, with directions that the case be 

remanded to the Service for further 

consideration consistent with the 

Court’s opinion (Western Watersheds 

Project v. Kempthorne, Case No. CV 07- 

161-E-MHW (D. Idaho)). 

After issuance of the Court’s remand 

order, we published a public 

notification of the reinstatement of our 

July 15, 2002, proposed rule to list 

Lepidium papilliferum as endangered 

and announced the reopening of a 

public comment period on September 

19, 2008 (73 FR 54345). The initial 

comment period closed on October 20, 

2008. After the close of the comment 

period, new information became 

available that was relevant to our 

evaluation. Much of this information 

was contained in reports based on 

several independent analyses of the 

available information regarding L. 

papilliferum population trends on the 

OTA in southwest Idaho, the rangewide 

Habitat Integrity and Population (HIP) 

monitoring, and a recent analysis of L. 

papilliferum data collected on the 

Inside Desert (Owyhee Plateau) from 

2000 to 2002. To ensure that our review 

of the species’ status was complete, we 

announced another reopening of the 

comment period on March 17, 2009, for 

a period of 30 days (74 FR 11342). We 

posted several documents on http:// 

www.regulations.gov for public review 

and comment, including the additional 

information and statistical analyses we 

received after the January 2007 

withdrawal notice (72 FR 1622; January 

12, 2007). A summary of the comments 

we received and our responses is 

provided in this document, following 

our finding. 

Species Information 

Description 

Lepidium papilliferum is an 

intricately branched, tap-rooted plant, 

averaging 2 to 8 inches (in) (5 to 20 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52015 

centimeters (cm)) high, but occasionally 

reaching 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 millimeters 

(mm)) in diameter, white, and four 

petalled. Fruits (siliques) are 0.1 in (3 to 

4 mm) across, round in outline, 

flattened, and two-seeded (Moseley 

1994, pp. 3, 4; Holmgren et al. 2005, p. 

260). The species is monocarpic (it 

flowers once and then dies) and 

displays two different life history 

strategies—an annual form and a 

biennial form. The annual form 

reproduces by flowering and setting 

seed in its first year, and dies within 

one growing season. The biennial life 

form initiates growth in the first year as 

a vegetative rosette, but does not flower 

and produce seed until the second 

growing season. Biennial rosettes must 

survive generally dry summer 

conditions, and consequently many of 

the biennial rosettes die before 

flowering and producing seed. The 

number of prior-year rosettes is 

positively correlated with the number of 

reproductive plants present the 

following year (ICDC 2008, p. 9; 

Unnasch 2008, p. 14; Sullivan and 

Nations 2009, p. 44). The proportion of 

annuals versus biennials in a population 

can vary greatly (Meyer et al. 2005, p. 

15), but in general annuals appear to 

outnumber biennials (Moseley 1994, p. 

12). 

Seed Production 

Depending on an individual plant’s 

vigor, the effectiveness of its 

pollination, and whether it is 

functioning as an annual or a biennial, 

each Lepidium papilliferum plant 

produces varying numbers of seeds 

(Quinney 1998, pp. 15, 17). Biennial 

plants normally produce many more 

seeds than annual plants (Meyer et al. 

2005, p. 15). Average seed output for 

annual plants at the OTA (an Idaho 

Army National Guard (IDARNG) 

training area on BLM land) was 125 

seeds per plant in 1993 and 46 seeds per 

plant in 1994. In contrast, seed 

production of biennials at this site in 

1993 and 1994 averaged 787 and 105 

seeds per plant, respectively (Meyer et 

al. 2005, p. 16). Based on data collected 

from a 4–year demography study on the 

OTA, survivorship of the annual form of 

L. papilliferum was demonstrated to be 

higher than survivorship of biennials 

(Meyer et al. 2005, p. 16). For example, 

of the 4,065 plants counted in spring of 

1993, a total of 2,503 survived to fruit 

as annuals, while only 85 survived to 

fruit as biennials in spring of 1994. 

Meyer et al. (2005, p. 21) hypothesize 

that the reproductive strategy of L. 

papilliferum is a plastic response, 

meaning that larger plants will flower 

and produce seed in their first season, 

whereas smaller plants that stand less 

chance of successfully setting seed in 

their first season will delay 

reproduction until the following year. 

The biennial life form is thus 

maintained, despite the higher risk of 

mortality. 

Like many short-lived plants growing 

in arid environments, above-ground 

numbers of Lepidium papilliferum 

individuals can fluctuate widely from 

one year to the next, depending on 

seasonal precipitation patterns 

(Mancuso and Moseley 1998, p. 1; 

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

et al. 2005, p. 9; Menke and Kaye 2006a, 

p. 8; Menke and Kaye 2006b, pp. 10, 11; 

Sullivan and Nations 2009, p. 44). 

Mancuso and Moseley (1998, p. 1) note 

that sites with thousands of aboveground plants one year may have none 

the next, and vice versa. Above-ground 

plants represent only a portion of the 

population; the seed bank (a reserve of 

dormant seeds, generally found in the 

soil) contributes the other portion, and 

in many years constitutes the majority 

of the population (Mancuso and 

Moseley 1998, p. 1). Seed banks are 

adaptations for survival in a ‘‘risky 

environment,’’ because they buffer a 

species from stochastic (random) 

impacts, such as lack of soil moisture 

(Baskin and Baskin 2001, p. 160). 

Seed Viability and Germination 

The seeds of Lepidium papilliferum 

are found primarily within the slickspot 

microsites where the plants are found 

(Meyer and Allen 2005, pp. 5, 6). 

Slickspots, also known as mini-playas 

or natric (high sodium content) sites, are 

visually distinct openings in the 

sagebrush-steppe created by unusual 

soil conditions characterized by 

significantly greater sodium and clay 

content relative to the surrounding area 

(Moseley 1994, p. 7). The vast majority 

of L. papilliferum seeds in slickspots 

have been located near the soil surface, 

with lower numbers of seeds located in 

deeper soils (Meyer et al. 2005, p. 19; 

Palazzo et al. 2005, p. 3). Lepidium 

papilliferum seeds have been found in 

slickspots even if no above-ground 

plants are present (Meyer et al. 2005, p. 

22; Palazzo et al. 2005, p. 10). When 

above-ground plants are present, 

flowering usually takes place in late 

April and May, fruit set occurs in June, 

and the seeds are released in late June 

or early July. 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 the initially 

viable seeds produced in a given year 

germinate annually (Meyer et al. 2005, 

pp. 17, 18). When combined with an 

average annual 3 percent loss of seed 

viability, approximately 9 percent of the 

original seed cohort per year is lost after 

the first year. Thus, after 12 years, all 

seeds in a given cohort will likely have 

either died or germinated, resulting in a 

maximum estimated longevity of 12 

years for seeds in the seed bank (Meyer 

et al. 2005, p. 18). 

Billinge and Robertson (2008, pp. 

1005-1006) report that both small and 

large Lepidium papilliferum 

populations share similar spatial 

structure, and that spatial structuring 

within its unique microsite slickspot 

habitats suggests that both pollen 

dispersal and seed dispersal are low for 

this species and occur over short 

distances (Robertson et al. 2006a, p. 3; 

Billinge and Robertson 2008, pp. 1005- 

1006). Modeling of dispersal and seed 

dormancy characteristics of desert 

annual plants predicts that plants with 

long-range dispersal will have few 

dormancy mechanisms and thus quick 

germination (Venable and Lawlor 1980, 

p. 272). Contrary to this prediction, 

however, L. papilliferum has delayed 

germination (Meyer et al. 2005, pp. 17- 

18), and, therefore, according to the 

model, may not disperse long distances. 

The primary seed dispersal mechanism 

for L. papilliferum is not known 

(Robertson and Ulappa 2004, p. 1708), 

although viable seeds have been found 

outside of slickspots, indicating that 

some seed dispersal is occurring beyond 

slickspot habitat (Palazzo et al. 2005, p. 

10). Additionally, beginning in midJuly, entire dried-up biennial plants and 

some larger annual plants have been 

observed to break off at the base and are 

blown by the wind (Stillman, pers. obs., 

as reported in Robertson et al. 2006b, p. 

44). This tumbleweed-like action may 

have historically resulted in occasional 

long-distance seed dispersal (Robertson 

et al. 2006b, p. 44). Ants are not 

considered to be a likely disperser 

despite harvesting an average of 32 

percent of fruits across six sites 

(Robertson and White 2007, p. 11). 

Lepidium papilliferum seeds located 

near the soil surface show higher rates 

of germination and viability (Meyer and 

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

p. 10) and the greatest seedling 

emergence success rate (Meyer and 

Allen 2005, pp. 6-8). Viable seeds were 

more abundant and had greater 

germination rates from the upper 2 in (5 

cm) of soil (Palazzo et al. 2005, pp. 8, 

10), while Meyer and Allen (2005, pp. 

6-8) observed the upper 0.08 in (2 mm) 

optimal for germination. Deep burial of 


srobinson on DSKHWCL6B1PROD with RULES4
52016 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

L. papilliferum seeds (average depths 

greater than 5.5 in (14 cm)) can entomb 

viable seeds and may preserve them 

beyond the 12–year period previously 

assumed as the maximum period of 

viability for L. papilliferum seeds 

(Meyer and Allen 2005, pp. 6, 9). 

However, seeds buried at such depth, 

even if they remain viable, are unlikely 

to regain the surface for successful 

germination. The effects of 

environmental factors such as wildfire 

on L. papilliferum seed dormancy and 

viability are currently unknown, 

although L. papilliferum abundance is 

reduced in burned areas (see discussion 

of Wildfire under Summary of Factors 

Affecting the Species). 

Pollination 

Lepidium papilliferum is primarily an 

outcrossing species requiring pollen 

from separate plants for more successful 

fruit production and has a low seed set 

in the absence of insect pollinators 

(Robertson 2003a, p. 5; Robertson and 

Klemash 2003, p. 339; Robertson and 

Ulappa 2004, p. 1707; Billinge and 

Robertson 2008, pp. 1005-1006). 

Lepidium papilliferum is able to selfpollinate; however, with a selfing rate 

(rate of self-pollination) of 12 to 18 

percent (Billinge 2006, p. 40; Robertson 

et al. 2006a, p. 40). In pollination 

experiments where researchers moved 

pollen from one plant to another, fruit 

production was observed to be higher 

with pollen from distant sources (4 to 

12.4 mi (6.5 to 20 km) distance between 

patches of plants) compared to fruit 

production for plants pollinated with 

pollen from plants within the same 

patch (246 to 330 feet (ft) (75 to 100 

meters (m)) distance within a plant 

patch) (Robertson and Ulappa 2004, p. 

1705; Robertson et al. 2006a, p. 3). 

Fruits produced from fertilized 

flowers reach full size approximately 2 

weeks after pollination (Robertson and 

Ulappa 2004, p. 1706). Each fruit 

typically bears two seeds that drop to 

the ground when the fruit dehisces 

(splits open) in midsummer (Billinge 

and Robertson 2008, p. 1003). 

Known Lepidium papilliferum insect 

pollinators include several families of 

bees (Hymenoptera), including Apidae, 

Halictidae, Sphecidae, and Vespidae; 

beetles (Coleoptera), including 

Dermestidae, Meloidae, and Melyridae; 

flies (Diptera), including Bombyliidae, 

Syrphidae, and Tachinidae; and others 

(Robertson and Klemash 2003, p. 336; 

Robertson et al. 2006b, p. 6). Seed set 

was not limited by the number of 

pollinators at any study site (Robertson 

et al. 2004, p. 14). Studies have shown 

a strong positive correlation between 

insect diversity and the number of L. 

papilliferum flowering at a site 

(Robertson and Hannon 2003, p. 8). 

Measurement of fruit set per visit 

revealed considerable variability in the 

effectiveness of pollination by different 

types of insects, ranging from 0 percent 

in dermestid beetles to 85 percent in 

honeybees (Robertson et al. 2006b, p. 

15). 

Genetics 

The majority of species in the genus 

Lepidium have a base chromosome 

count of eight (Mummenhoff et al. 2001, 

p. 2051). Chromosome numbers for 

pollen mother cells in L. papilliferum 

ranged from 15 to 17 (n = 15.96 ± 0.16; 

Table 3; Figure 3), confirming that the 

plant is a tetraploid (has four sets of 

homologous chromosomes, as opposed 

to the more usual set of two) (Robertson 

et al. 2006b, p. 38). 

The genetics of Lepidium papilliferum 

have been studied using samples 

collected from areas across the entire 

range of the species (Stillman et al. 

2005, pp. 6, 8, 9; Larson et al. 2006, p. 

14 and Fig. 4; Smith et al. in press, pp. 

15-16). Genetic exchange can occur 

either through pollen or seed dispersal. 

Some researchers consider L. 

papilliferum to be closely related to L. 

montanum, and L. papilliferum was 

originally described as L. montanum 

var. papilliferum in 1900 by Louis 

Henderson. Results of 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). A more recent study 

examining the relationship between L. 

montanum, L. papilliferum, and L 

fremontii found that L. papilliferum is 

considered a sister taxa or closely 

related to L. fremontii, a native mustard 

of western North America (Smith et al. 

in press, pp. 15-16). Both L. fremontii 

and L. papilliferum are morphologically 

and ecologically distinct from L. 

montanum, and recent analyses reflect 

that both are monophyletic (organisms 

that share a common ancestor) with 

apparently little gene flow between 

them and L. montanum (Smith et al. in 

press, p. 18). 

Some genetic differences have been 

observed between Lepidium 

papilliferum occurring on the Snake 

River Plain (now separated into the 

Boise Foothills and Snake River Plain 

regions) and the Owyhee Plateau. Plants 

in the Snake River Plain and the 

Owyhee Plateau populations are 

separated by a minimum of 44 mi (70 

km), which is considered beyond the 

distance that insect pollinators can 

travel or that seed dispersal can occur. 

Sites in the Snake River Plain with 

fewer numbers of plants (16 to 746 

flowering individuals) had less genetic 

diversity than sites with larger numbers 

of plants (more than 3,000 flowering 

individuals) (Robertson et al. 2006b, p. 

42; Billinge and Robertson 2008, p. 

1006), although this correlation between 

population size and genetic diversity 

was not evident in the Owyhee Plateau 

region (Stillman et al. 2005, p. 9; 

Robertson et al. 2006b, p. 41). The 

lowest values for average number of 

alleles per locus were detected in two of 

the smallest populations (Seaman’s 

Gulch in the Boise Foothills region and 

Orchard in the Snake River Plain 

region); in contrast, the largest number 

of alleles per locus was detected in the 

second largest population (Kuna Butte 

SW in the Snake River Plain) (Robertson 

et al. 2006b, Table 4). Larson et al. 

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

geographically well-defined populations 

of L. 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). 

In summary, recent genetic studies 

thus confirm that Lepidium papilliferum 

is a full species distinct from L. 

montanum. 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), 2009). In 

addition, populations of L. papilliferum 

in the Owyhee Plateau demonstrate 

distinctive genetic differences from 

individuals in the Snake River Plain, 

likely a reflection of the isolation of 

these two populations due to limited 

seed dispersal and the limited range of 

pollinators, resulting in little current 

gene flow between them. Finally, there 

is some evidence that L. papilliferum 

has reduced genetic variability relative 

to other native species of Lepidium, 

such as L. montanum, and that smaller 

populations of L. papilliferum have less 

genetic diversity than larger 

populations. 

Monitoring of Lepidium papilliferum 

Populations 

There are several biological programs 

designed to monitor populations of 

Lepidium papilliferum over time, and, 

in some cases, its habitat as well. The 

primary monitoring programs are 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52017 

described here to assist in 

understanding subsequent references to 

them in this document. 

The Idaho Natural Heritage Program 

(INHP) uses element occurrences (EOs) 

to broadly describe the distribution of 

Lepidium papilliferum and assigns 

rankings to each EO based on measures 

of habitat quality and species 

abundance. EOs of L. papilliferum are 

defined by grouping occupied slickspots 

that occur within 1 km (0.6 mi) of each 

other; all occupied slickspots within a 1 

km (0.6 mi) distance of another 

occupied slickspot are aggregated into a 

single EO. The definition of a single EO 

is based on the distance over which 

individuals of L. papilliferum are 

believed to be capable of genetic 

exchange through insect-mediated 

pollination (Colket and Robertson 2006). 

Due to the nature of their definition, 

individual EOs may differ greatly in 

size, based on whether there are many 

occupied slickspots distributed widely 

across the landscape relatively close to 

one another (which would comprise a 

single, large EO), or whether there are 

only a few (or even a single) slickspot(s) 

that occur close together but are 

relatively isolated from other occupied 

slickspots (which would comprise a 

single, small EO). 

Each EO is assigned a qualitative rank 

defined by population size and habitat 

quality; EO ranks are periodically 

updated when new ranking information 

becomes available. Currently, no 

Lepidium papilliferum EOs are ranked 

A, which is defined as an EO with 

greater than 1,000 detectable aboveground plants occurring in the best 

habitat and landscape quality. The 

habitat quality rank diminishes from the 

highest of A to the lowest quality of D. 

An E ranking signifies that at least one 

plant was observed, but no abundance, 

habitat, or landscape data are available 

(Colket et al. 2006, p. 4). A rank of F 

indicates the most recent survey failed 

to find any L. papilliferum plants. A 

rank of H indicates L. papilliferum 

plants have not been documented at that 

location since 1970 based on old 

herbarium records with geographically 

vague location descriptions, such as a 

town name. A rank of X indicates L. 

papilliferum plants had been extirpated 

from that EO, based on agricultural 

conversion, commercial or residential 

development, or other documented 

habitat destruction where L. 

papilliferum plants had been previously 

recorded. An EO can also be ranked as 

X if it receives an F rank five times 

within a 12–year period (Colket et al. 

2006, p. 4). The current rankings for L. 

papilliferum are reviewed below in the 

section Element Occurrences 

Rangewide. 

The Habitat Integrity Index (HII) 

program conducted by the Idaho 

Conservation Data Center (ICDC, now 

the INHP) was the first rangewide effort 

aimed at monitoring Lepidium 

papilliferum and its habitat. The HII was 

initiated in 1998 and ran for 5 years 

through 2002 (Mancuso and Moseley 

1998; Mancuso et al. 1998; Mancuso 

2000, 2001, 2002, 2003). Although 52 

transects were established over the 

years, a total of 17 transects were 

sampled during all years of HII 

monitoring (Mancuso 2003, p. 3); no 

rangewide monitoring of L. papilliferum 

was conducted in 2003. Monitoring was 

initially based on a system of transects 

of varying lengths across the range of L. 

papilliferum, each subjectively located 

to include 10 slickspots on sites known 

to contain L. papilliferum (summarized 

in Sullivan and Nations 2009, p. 33; see 

Mancuso et al. 1998 for details). The 

primary goal of the HII methodology 

was to assess the overall habitat 

condition, including attributes 

associated with the slickspots and the 

sagebrush-steppe habitat; L. 

papilliferum abundance was assessed 

categorically (assigned to a range of 

values) in this program. 

In 2004, the HII was replaced by the 

Habitat Integrity and Population (HIP) 

monitoring protocol, also implemented 

by the ICDC. HIP monitoring has been 

conducted annually since its 

implementation, thus 5 years of HIP 

data are now available (through 2008) 

(ICDC 2008, p. 2; State of Idaho 2008). 

The HIP protocol was designed to 

provide data more replicable and 

specific to the monitoring required for 

the Candidate Conservation Agreement 

(CCA) developed by the State of Idaho, 

BLM, and others in 2003 (State of Idaho 

et al. 2003). HIP presents measures of 

habitat, disturbance, and plant 

community attributes at each transect as 

well as counts of L. papilliferum rosettes 

and reproductive plants observed (with 

the exception of 2004, which still 

utilized categorical assessments of plant 

abundance). Similar to the HII protocol, 

HIP is based on transects of varying 

lengths subjectively located to include 

10 slickspots along their lengths (see 

Colket 2005 for details on the HIP 

methodology); however, the HIP 

protocol includes a significantly greater 

number of rangewide transects, having 

increased from the original 70 

established in 2004 to 80 today (ICDC 

2008, p. 3). 

HIP monitoring has been annually 

conducted since 2004 and consists of 

the following procedures: (1) Establish 

and permanently mark HIP transects; (2) 

record location information; (3) take 

photographs; (4) measure population, 

habitat, and disturbance attributes at 

selected slickspots; (5) measure plant 

community attributes; and (6) analyze 

and describe the results (Colket 2008, p. 

3). 

The INHP’s EO records and the HII– 

HIP monitoring programs cover the 

entire range of Lepidium papilliferum. 

In addition, monitoring that has 

occurred within a subset of the species’ 

range, on the Idaho Army National 

Guard’s Orchard Training Area (OTA), 

provides particularly important 

information on the status of L. 

papilliferum due to the long-term nature 

of the monitoring programs. The 

sagebrush-steppe on the OTA is 

considered to be some of the highestquality habitat remaining within the 

range of L. papilliferum, and the OTA is 

home to one of the largest and most 

expansive EOs of the species (Sullivan 

and Nations 2009, p. 22). Two of the 

OTA programs have been monitoring 

the same locations annually (with a few 

exceptions) since the early 1990s, and 

hence provide up to 18 years of 

population data for L. papilliferum. 

These two monitoring programs are 

known as rough census areas and 

special-use plots; both are conducted by 

staff or contractors of the OTA. 

The methods of the rough census 

monitoring areas are presented in 

Sullivan and Nations 2009 (pp. 28-29). 

Briefly, the program began in 1990 by 

monitoring 5 areas but expanded to the 

current total of 15 rough census areas by 

1994; the combined extent of the rough 

census areas on the OTA is 866.1 ac 

(350.5 ha). Counts are conducted by 

technicians who walk across parallel 

transects 66 ft (20 m) apart and record 

the total number of Lepidium 

papilliferum individuals observed in 

any occupied slickspots that are found; 

reproductive status is not noted. The 

sizes of the 15 rough census areas differ, 

ranging from 4.1 ac (1.7 ha) to 138.3 ac 

(56.0 ha), and not all areas have been 

monitored in all years; thus, analyses of 

the data must be standardized by 

transforming the raw count data to plant 

density (number of plants per unit area) 

to account for these differences 

(Sullivan and Nations 2009, p. 36). 

Using density as the index of population 

abundance instead of total counts also 

allowed for the use of 18 years of rough 

census data, from 1990 through 2008 

(there were no counts in 1999), although 

only a few of the rough census areas 

were monitored in the earlier years. 

The special-use plots are also located 

on the OTA. Although called ‘‘plots,’’ 

these are actually a series of 16 belt 

transects, each containing a single 


srobinson on DSKHWCL6B1PROD with RULES4
52018 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

slickspot (see Sullivan and Nations 

2009, pp. 29-33, for details). A stake is 

centered in the single slickspot, and 

each year the number of Lepidium 

papilliferum individuals with a 16.4-ft 

(5-m) radius of that stake (comprising a 

32.8-ft (10-m) diameter circle) are 

counted (additional habitat information 

is collected from the remainder of the 

belt transect). Lepidium papilliferum 

abundance estimates for each of the 16 

central circular plots has been collected 

annually each year from 1991 through 

2008; thus, 18 years of special-use plot 

data are available. As all special-use 

plots were the same size and were 

surveyed in all years, estimates of 

abundance are based on reported total 

counts of individual plants (Sullivan 

and Nations 2009, p. 37). Beginning in 

2000, the special-use plot data 

distinguished between blooming and 

nonblooming individuals. 

All of these programs provide 

information regarding the status of 

Lepidium papilliferum and its habitat, 

and will be referenced throughout this 

rule. In addition, we reference L. 

papilliferum Management Areas, which 

are units containing multiple EOs in a 

particular geographic area with similar 

land management issues or 

administrative boundaries as defined in 

the 2003 CCA (State of Idaho, p. 9). At 

a larger scale is the L. papilliferum (or 

‘‘LEPA’’) Consideration Zone, an area 

also designated by the 2003 CCA and 

defined as all areas that may or do 

contain L. papilliferum (State of Idaho 

2003, p. 21). The LEPA Consideration 

Zone includes the entire range of the 

species, including all Management 

Areas and all EOs. 

Ecology and Habitat 

The native, semiarid sagebrush-steppe 

habitat of southwestern Idaho where 

Lepidium papilliferum is found can be 

divided into two plant associations, 

each dominated by the shrub Artemisia 

tridentata ssp. wyomingensis (Wyoming 

big sagebrush): A. tridentata ssp. 

wyomingensis–Achnatherum 

thurberianum (formerly Stipa 

thurberiana) (Thurber’s needlegrass) 

and A. tridentata ssp. wyomingensis– 

Agropyron spicatum (bluebunch 

wheatgrass) habitat types (Moseley 

1994, p. 9). The perennial bunchgrasses 

Poa secunda (Sandberg’s bluegrass) and 

Sitanion hysrix (bottlebrush squirreltail) 

are commonly found in the understory 

of these habitats, and the species 

Artemisia tridentata ssp. tridentata 

(basin big sagebrush), Chrysothamnus 

nauseosus (grey rabbitbrush), 

Chrysothamnus viridiflorus (green 

rabbitbrush), Eriogonum strictum (strict 

buckwheat), Purshia tridentata 

(bitterbrush), and Tetradymium glabrata 

(little-leafed horsebrush) form a lesser 

component of the shrub community 

(Moseley 1994, p. 9; Mancuso and 

Moseley 1998, p. 17). Under relatively 

undisturbed conditions, the understory 

is populated by a diversity of perennial 

bunchgrasses and forbs, including 

species such as Achnatherum (formerly 

Oryzopsis) hymenoides (Indian 

ricegrass), Achillea millefolium 

(common yarrow), Phacelia 

heterophylla (varileaf phacelia), 

Astragalus purshii (Pursh’s milkvetch), 

Phlox longifolia (longleaf phlox), and 

Aristida purpurea var. longiseta (purple 

threeawn) (Moseley 1994, p. 9; Mancuso 

and Moseley 1998, p. 17; Colket 2005, 

pp. 2-3). Menke and Kaye (2006a, p. 1) 

describe high quality matrix habitat 

conditions for L. papilliferum as 

sagebrush-steppe habitat in late seral 

condition, and Fisher et al. (1996, p. 1) 

note that ‘‘habitat with vigorous 

Lepidium populations has not been 

recently burned, is not heavily grazed, 

has an understory of native 

bunchgrasses, and a well developed 

microbiotic soil crust.’’ Moseley (1994, 

p. 4) suggests that L. papilliferum serves 

as an indicator species for the health of 

the sagebrush-steppe ecosystem in the 

western Snake River Plain. 

The biological soil crust, also known 

as a microbiotic crust or cryptogamic 

crust, is one component of quality 

habitat for Lepidium papilliferum. Such 

crusts are commonly found in semiarid 

and arid ecosystems, and are formed by 

living organisms, primarily bryophytes, 

lichens, algae, and cyanobacteria, that 

bind together surface soil particles 

(Moseley 1994, p. 9; Johnston 1997, p. 

4). Microbiotic crusts play an important 

role in stabilizing the soil and 

preventing erosion, increasing the 

availability of nitrogen and other 

nutrients in the soil, and regulating 

water infiltration and evaporation levels 

(Johnston 1997, pp. 8-10). In addition, 

an intact crust appears to aid in 

preventing the establishment of invasive 

plants (Brooks and Pyke 2001, p. 4, and 

references therein; see also Serpe et al. 

2006, pp. 174, 176). These crusts are 

sensitive to disturbances that disrupt 

crust integrity, such as compression due 

to livestock trampling or off-roadvehicle (ORV) use, and are also subject 

to damage by fire; recovery from 

disturbance is possible but occurs very 

slowly (Johnston 1997, pp. 10-11). 

As described earlier, Lepidium 

papilliferum occurs in slickspot habitat 

microsites scattered within the greater 

semiarid sagebrush-steppe ecosystem of 

southwestern Idaho. Lepidium 

papilliferum has infrequently been 

documented outside of slickspots, on 

occasion being found on disturbed soils, 

such as along graded roadsides and 

badger mounds. These are rare 

observations and the vast majority of 

plants documented over the past 19 

years of surveys and monitoring for the 

species are documented within 

slickspot microsite habitats (USFWS 

2006, p. 20). For example, in 2002, a 

complete census of an 11,070-ac (4,480- 

ha) area recorded approximately 56,500 

slickspots (U.S. Air Force, 2003, p. 15), 

of which approximately 2,450 (about 4 

percent) were occupied by L. 

papilliferum plants (Bashore, pers. 

comm. 2003, p. 1). Of the approximately 

11,300 L. papilliferum plants 

documented during the survey effort, 

only 11 plants were documented 

outside of slickspots (U.S. Air Force 

2002, in summary attachment of 

document). 

Slickspots are visually distinct 

openings characterized by soils with 

high sodium content and distinct clay 

layers; they tend to be highly reflective 

and relatively light in color, which 

makes them easy to detect on the 

landscape (Fisher et al. 1996, p. 3). 

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), sparse 

native vegetation, distinct soil layers 

with a columnar or prismatic structure, 

higher alkalinity and clay content and 

natric properties (Fisher et al. 1996, pp. 

15-16; Meyer and Allen 2005, pp. 3-5, 

8; Palazzo et al. 2008, p. 378), and 

reduced levels of organic matter and 

nutrients due to lower biomass 

production (Meyer and Quinney 1993, 

pp. 3, 6; Fisher et al. 1996, p. 4). Fisher 

et al. (1996, p. 11) describe slickspots as 

having a ‘‘smooth, panlike surface’’ that 

is structureless and slowly permeable 

when wet, moderately hard and cracked 

when dry. Although the low 

permeability of slickspots appears to 

help hold moisture (Moseley 1994, p. 8), 

once the thin crust dries, out the 

survival of L. papilliferum seedlings 

depends on the ability to extend the 

taproot into the argillic horizon (soil 

layer with high clay content), to extract 

moisture from the deeper natric zone 

(Fisher et al. 1996, p. 13). 

Slickspots have three primary layers: 

The surface silt layer, the restrictive 

layer, and an underlying moist clay 

layer. Although slickspots can appear 

homogeneous on the surface, the actual 

depth of the silt and restrictive layer can 

vary throughout the slickspot (Meyer 

and Allen 2005; Tables 9, 10, and 11). 

The top two layers (surface silt and 

restrictive) of slickspots are normally 

very thin; the surface silt layer varies in 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52019 

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 rangewide mean 

surface silt layer depth was 0.31 in (0.78 

cm) based on a 2005 study of 769 

slickspots of unknown occupancy 

sampled at 79 transects (Colket 2006, p. 

38). Additionally, measurements of the 

depth of the clay layer next to L. 

papilliferum plants at the Juniper Butte 

Training Range were taken in 2007 and 

2008 to assess if depth of the clay layer 

could be a significant factor for plant 

germination. The average depth of the 

clay layer next to plants measured in 

2007 was 2.5 in (6.3 cm), with a range 

from 1.2 to 4.7 in (3.0 to 12.0 cm) 

(n=18), and in 2008 was 2.1 in (5.4 cm) 

with a range from 1.6 to 3.1 in (4.0 to 

8.0 cm) (n=16) (CH2MHill 2008a, p. 13). 

It appears that depth to the clay layer is 

not as critical to germination at the 

Juniper Butte Training Range as other 

factors may be (such as depth to surface 

of the soil, the timing and amount of 

moisture, seed bank, and ability of the 

slickspot to capture and maintain 

adequate moisture). 

It is not known how long slickspots 

take to form, but it is hypothesized to 

take several thousands of years 

(Nettleton and Peterson 1983, p. 193; 

Seronko 2006). Climate conditions that 

allowed for the formation of slickspots 

in southwestern Idaho are thought to 

have occurred during a wetter 

Pleistocene period. Holocene additions 

of wind-carried salts (often loess 

deposits) produced the natric soils (high 

in sodium) characteristic of slickspots 

(Nettleton and Peterson 1983, p. 191; 

Seronko 2006). It may take several 

hundred years to alter or lose slickspots 

through natural climate change or 

severe natural erosion (Seronko 2006). 

Some researchers hypothesize that, 

given current climatic conditions, new 

slickspots are no longer being created 

(Nettleton and Peterson 1983, pp. 166, 

191, 206). As slickspots appear to have 

formed during the Pleistocene and new 

slickspots are not being formed, the loss 

of a slickspot is apparently a permanent 

loss. 

Some slickspots subjected to light 

disturbance in the past may apparently 

be capable of re-forming (Seronko 2006). 

Disturbances that alter the physical 

properties of the soil layers, however, 

such as deep disturbance and the 

addition of organic matter, may lead to 

destruction and permanent loss of 

slickspots. For example, such 

techniques as deep soil tilling, the 

addition of organic matter, and addition 

of gypsum have been recommended for 

the elimination of slickspots from 

agricultural lands in Idaho (Peterson 

1919, p. 11; Rasmussen et al. 1972, p. 

142). Slickspot soils are especially 

susceptible to mechanical disturbances 

when wet (Rengasmy et al. 1984, p. 63; 

Seronko 2004). Such disturbances 

disrupt the soil layers important to 

Lepidium papilliferum seed germination 

and seedling growth, and alter 

hydrological function. 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 regain their 

pre-disturbance configuration, yet not 

support the species. Thus, while the 

slickspot appears to have regained its 

former character, some essential 

component required to sustain the life 

history requirements of L. papilliferum 

has apparently been lost, or the active 

seed bank is no longer present. 

Most slickspots are between 10 square 

feet (ft2) and 20 ft2 (1 square meter (m2) 

and 2 m2) in size, although some are as 

large as 110 ft2 (10 m2) (Mancuso et al. 

1998, p. 1). 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 2002 

inventory of the 11,070 acre (ac) (4,480 

hectare (ha)) Juniper Butte Range on the 

Owyhee Plateau found approximately 1 

percent (109 ac (44 ha)) of the 

sagebrush-steppe area consisted of 

slickspot habitat, and of that slickspot 

habitat, only 4 percent (4 ac (1.6 ha)) 

was occupied by above-ground L. 

papilliferum plants (U.S. Air Force 

2002, p. 9). It is not known why L. 

papilliferum is not found in a greater 

proportion of slickspot microsites 

(Fisher et al. 1996, p. 15). 

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)). 

Precipitation tends to fall as rain, 

primarily in winter and spring 

(November to May); the lowest rainfall 

occurs in July and August, with the 

months of June, September, and October 

receiving slightly more rainfall than July 

and August. Average annual 

precipitation patterns vary within the 

species’ range, and are generally higher 

in the northern regions (e.g., 11.7 in 

(29.7 cm) near Boise, 7.4 in (18.8 cm) at 

the city of Bruneau, and 9.9 in (25.1 cm) 

at Mountain Home). 

Several analyses have shown a 

positive association between aboveground abundance of Lepidium 

papilliferum and spring precipitation in 

the same year. Evaluating rangewide HII 

monitoring data collected over 4 years 

from 1998 to 2001, Palazzo et al. (2005, 

p. 9) found a positive relationship (pvalue less than 0.01) between 

abundance of above-ground plants and 

February to June precipitation. 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 based on L. 

papilliferum census and survival data 

collected from 1993 to 1995. CH2MHill 

(2007a, p. 14) analyzed data from 2005 

to 2007 collected at the Juniper Butte 

Range in the Owyhee Plateau region and 

found a positive correlation between 

spring precipitation and plant numbers. 

Utilizing HII monitoring data collected 

from 1998 to 2002, as well as 2004 HIP 

monitoring data, Menke and Kay (2006a, 

b) found that March to May 

precipitation accounted for 99.4 percent 

of the variation in L. papilliferum 

abundance for the years 1998 to 2001 

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

years 1998 to 2002, and 2004 (2006b, 

pp. 10-11). These results appear to have 

been strongly influenced by the data 

point for 1998, which was an unusually 

wet spring (Unnasch 2008, p. 16). 

Because the 1998 HII data represents an 

outlier with respect to both L. 

papilliferum abundance and 

precipitation, it largely determines the 

regression relationship by itself; thus, 

Menke and Kaye’s 2006 conclusion that 

abundance increases with spring 

precipitation is not well supported 

(Sullivan and Nations 2009, p. 140). 

More recently, however, Sullivan and 

Nations (2009, pp. 30, 41) analyzed data 

collected at the OTA over a period of 18 

years between 1990 and 2008, and 

found evidence that both plant density 

at the rough census areas and plant 

abundance at special-use plots were 

positively related to mean monthly 

precipitation in late winter and spring 

(January through May). Thus, analysis of 

this long-term dataset again points to a 

strong relationship between L. 

papilliferum abundance and spring 

precipitation. This correlation of 

abundance with spring rainfall is 

important, as it at least partially 

explains annual fluctuations in L. 

papilliferum population numbers. 

In contrast, precipitation in the fall or 

early winter may have a negative effect 

on Lepidium papilliferum abundance 

the following spring (Meyer et al. 2005, 

p. 15; Sullivan and Nations 2009, p. 39). 

It has been suggested that this negative 


srobinson on DSKHWCL6B1PROD with RULES4
52020 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

relationship may be the result of 

prolonged flooding of the slickspot 

microsites, causing subsequent 

mortality of overwintering biennial 

rosettes (Meyer et al. 2005, pp. 15-16). 

This suggestion is supported by the 

analysis of 9 years of OTA data from the 

period 2000-2008 that shows a negative 

association between October to January 

precipitation and abundance of nonblooming L. papilliferum the following 

spring, although only the relationship 

with October to December precipitation 

is statistically significant (Sullivan and 

Nations 2009, p. 43). For blooming 

plants, the negative association between 

October to January precipitation and 

spring abundance was highly significant 

(Sullivan and Nations 2009, pp. 43-44). 

However, Unnasch (2008, p. 2) found 

no relationship between precipitation 

and the abundance of Lepidium 

papilliferum in an analysis of HIP data 

collected over a 3–year period from 

2005 to 2007. Unnasch hypothesized 

that L. papilliferum may manifest 

threshold effects in germination and 

that there is a pulse of germination 

following a requisite amount of rainfall 

that could lead to a major flush of L. 

papilliferum germination during very 

wet years. If total rainfall is below that 

threshold, annual germination is more 

random (Unnasch 2008, p. 16). 

Comparing his results to those of Menke 

and Kaye, Unnasch (2008, p. 15) 

suggests that the relationship with 

spring precipitation reported by Menke 

and Kaye was strongly affected by 

abundance data from the year 1998, 

although in turn the relatively short 3– 

year study period may have influenced 

Unnasch’s study results. Sullivan and 

Nations (2009, pp. 140, 142) likewise 

suggested that the exceptionally high 

precipitation in 1998 likely influenced 

the results of Menke and Kaye’s 

analysis. However, as described above, 

Sullivan and Nation’s more robust 

analysis of 18 years of data from the 

OTA confirmed a positive correlation 

between spring precipitation and the 

abundance of L. papilliferum (Sullivan 

and Nations 2009, pp. 40-44). As both 

annual precipitation and plant 

abundance are highly variable, the 

numbers of years included in the data 

set for evaluation is of great importance 

in determining the degree of confidence 

in the outcome of any statistical 

analysis. For this reason, the Service 

believes the Sullivan and Nations (2009, 

pp. 40-44) evaluation of the 18–year 

dataset from the OTA is the best 

available data regarding the relationship 

between precipitation and abundance of 

L. papilliferum. 

Recent analyses suggest that 

temperature also influences the annual 

abundance of Lepidium papilliferum. 

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

found that minimum and maximum 

temperatures were not statistically 

correlated with L. papilliferum 

abundance based on a limited number 

of years of data, Sullivan and Nations 

(2009, p. 46-57) used more precise 

temperature data in concert with the 

18–year L. papilliferum abundance 

dataset from the OTA to evaluate the 

potential interaction between 

precipitation, temperature, and plant 

abundance. Their analysis of the data 

collected between 1990 and 2008 

suggests a complex relationship 

between temperature and precipitation 

that influences the abundance of L. 

papilliferum on an annual basis. In 

short, they found that temperature and 

precipitation interact during the months 

of October through January such that the 

lowest density or abundance of L. 

papilliferum in the spring follows a fall 

or early winter when both precipitation 

and temperature are low, or both are 

high. Spring plant density or abundance 

is greatest following a fall or early 

winter when either precipitation is high 

and temperature is low, or precipitation 

is low and temperature is high (Sullivan 

and Nations 2009, p. 56). During late 

winter and spring, analysis of one OTA 

dataset (the ‘‘rough census’’ areas) 

suggested that temperature had a 

negative impact on L. papilliferum 

density, such that density is greater 

when precipitation is high but 

temperatures during March through 

May are lower (Sullivan and Nations 

2009, p. 47), whereas the model of the 

OTA special-use plots suggests only a 

positive interaction of L. papilliferum 

abundance with precipitation during 

this time period, with no temperature 

effect (Sullivan and Nations 2009, p. 

47). Sullivan and Nations caution that 

the limited geographic area within 

which the interactions of precipitation 

and temperature were studied limits the 

ability to extrapolate the observed 

relationship beyond the bounds of the 

OTA (Sullivan and Nations 2009, p. 57). 

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 (e.g., Moseley 1994, p. 8, 14; 

Fisher et al. 1996, pp. 11, 16). Plant 

ecology literature suggests that plants 

tolerant of stress (e.g., plants that are 

capable of growing in harsh alkaline 

soils) are poor competitors (Grime 1977, 

p. 1185), making L. papilliferum a 

potentially poor competitor with other 

plants. In recent years, there are 

increasing observations of nonnative 

plants encroaching into slickspots, and 

consistent with theory, the evidence 

suggests that L. papilliferum is not able 

to successfully compete with these 

invasive exotics. Sullivan and Nations 

(2009, p. 111) report an ‘‘apparent 

mutual exclusivity’’ between nonnative 

plant species examined and L. 

papilliferum in slickspots. In other 

words, if plants such as Bassia prostrata 

(prostrate kochia or forage kochia, 

formerly Kochia prostrata) or Bromus 

tectorum are present in a slickspot, L. 

papilliferum is most often reduced in 

numbers or entirely absent. 

Range and Distribution 

The range of Lepidium papilliferum is 

restricted to the volcanic plains of 

southwest Idaho, occurring primarily in 

the Snake River Plain and its adjacent 

northern foothills, with a single disjunct 

a population on the Owyhee Plateau 

(Figure 1). 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- 

9). Based on differences in topography, 

soil, and relative abundance, we have 

further divided the extant Lepidium 

papilliferum populations into three 

physiographic regions: the Boise 

Foothills, the Snake River Plain, and the 

Owyhee Plateau. The nature and 

severity of factors affecting the species 

also vary between the three 

physiographic regions for the purposes 

of analysis. For example, urban and 

rural development, agriculture, and 

infrastructure development has been 

substantial in the sagebrush-steppe 

habitat of the Boise Foothills and the 

Snake River Plain regions, while very 

little of these types of development has 

occurred within the Owyhee Plateau 

region. Genetic analyses reveal some 

separation between the greater Snake 

River Plain and Owyhee Plateau 

populations of L. papilliferum (Larson et 

al. 2006, p. 14), as might be expected 

due to their relative isolation. We are 

not aware of any studies that may have 

examined the relative genetic 

differentiation, if any, of the Boise 

Foothills population from the remainder 

of the Snake River Plain. 

Figure 1. Range of Lepidium 

papilliferum in southwest Idaho, 

showing its distribution in the three 

physiographic provinces of the Snake 

River Plain, Boise Foothills, and 

Owyhee Plateau. 

BILLING CODE 4310–55–S 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52021 

BILLING CODE 4310–55–C 

As of February 2009, there were 80 

extant EOs in the three physiographic 

regions that collectively comprise 

approximately 15,801 ac (6,394 ha) of 

total area that is broadly occupied by 

Lepidium papilliferum (Cole 2009b, 

Threats Table). The area actually 

occupied by L. papilliferum is a small 

fraction of the total acreage, since 

slickspots occupy only a small 

percentage of the landscape, and L. 

papilliferum then occupies only a 

fraction of those slickspots (see U.S. Air 

Force 2002, p. 9, for an example). Table 

1 presents the distribution and 

landownership and management 

information for all L. papilliferum EOs, 

in total and by region. 


srobinson on DSKHWCL6B1PROD with RULES4ER08OC09.000</GPH>
52022 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

TABLE 1. DISTRIBUTION AND LAND OWNERSHIP OF Lepidium papilliferum ELEMENT OCCURRENCES BY PHYSIOGRAPHIC

REGION (COLE 2009B, THREATS TABLE; SULLIVAN AND NATIONS 2009, P. 77). 

All areas are estimates, and may not total exactly due to rounding. 

Lepidium papilliferum 

EOs 

Number of EOs 

[percent of total] 

Federal ownership in 

acres 

(hectares) 

[percent of total] 

State ownership 

in acres 

(hectares) 

[percent of total] 

Private ownership 

in acres 

(hectares) 

[percent of total] 

Total EO Area 

(hectares) 

[percent of total 

rangewide 

EO area] 

Snake River Plain 43 

[54] 

12,754 ac 

(5,160 ha) 

[98] 

55 ac 

(22 ha) 

[0.5] 

164 ac 

(66 ha) 

[1.5] 

12,980 ac 

(5,250 ha) 

[82] 

Boise Foothills 16 

[20] 

89 ac 

(36 ha) 

[48] 

0 ac 

(0 ha) 

0 

96 ac 

(39 ha) 

[52] 

185 ac 

(75 ha) 

[1.2] 

Owyhee Plateau 21 

[26] 

2,636 ac 

(1,067 ha) 

[99.7] 

7 ac 

(3 ha) 

[0.3] 

0 ac 

(o ha) 

[0] 

2,643 ac 

(1,070 ha) 

[16. 8%] 

All extant 

EOs 

80 

[100] 

15,479 ac 

(6,264 ha) 

[98.0] 

62 ac 

(25 ha) 

[0.4] 

260 ac 

(105 ha) 

[1.6] 

15,801 ac 

(6,394 ha) 

[100] 

The range of Lepidium papilliferum 

was first estimated in 1994 (Moseley 

1994, p. 6). Expanded survey efforts in 

recent years have resulted in an increase 

in the amount of known occupied 

habitat, particularly on the Owyhee 

Plateau and in the Boise Foothill 

regions. Between 2003 and 2006, 16 

new EOs were documented, all within 

3 mi (4.8 km) of previously existing 

EOs: 2 on the Snake River Plain with a 

total area of 2.7 ac (1 ha), and 14 on the 

Owyhee Plateau with a total area of 46.6 

ac (18 ha) (Colket et al. 2006, Tables and 

Appendix A). Since 2006, additional 

surveys of previously unsurveyed lands 

have resulted in the discovery of several 

new occupied sites. Because most of 

these newly discovered sites were 

within 1 km (0.6 mi) of a documented 

EO, they typically resulted in the 

expansion or merging of existing EOs 

rather than the creation of a new EO. 

For example, in 2007, 2,560 ac (1,036 

ha) of BLM land on the Owyhee Plateau 

were inventoried for L. papilliferum just 

south of the U.S. Air Force’s Juniper 

Butte Training Range. Of the 2,171 

slickspots surveyed, 200 (9 percent) 

were occupied by L. papilliferum with 

a total of 1,059 flowering plants and 214 

rosettes (ERO 2007, pp. 1, 7-8), resulting 

in the expansion of EO 16 (Cole 2009a, 

p. 38). Surveys conducted in 2008 in the 

vicinity of the Ada County landfill in 

the Boise Foothills region revealed 

nearly 5,000 plants in 75 slickspots 

(Cole 2008, p. 8), which expanded the 

size of existing EOs 38 and 65 (Cole 

2009a, p. 39). Pre-development surveys 

conducted during 2007 by URS 

Corporation (URS) on BLM and private 

lands in the Boise Foothills region 

northwest of the City of Eagle detected 

43 occupied slickspots out of 187 

surveyed, with approximately 17,880 L. 

papilliferum plants (URS 2008, p. 10). 

These observations expanded the total 

area of EO 76 (Cole 2009a, p. 39). 

Finally, additional survey efforts on 

previously surveyed areas at the OTA 

resulted in the documentation of 365 

new occupied slickspots in 2005, 

resulting in further expansion of 

existing EO 27 (URS 2005, pp. 6-7). 

Not all potential Lepidium 

papilliferum habitats in southwest 

Idaho have been surveyed, and it is 

possible that additional L. papilliferum 

sites may be found outside of areas that 

are currently known to be occupied. 

Recent modeling was completed to 

develop a high-quality, predictivedistribution model of L. papilliferum to 

identify potential habitat (Colket 2008, 

p. 1). Although surveys were conducted 

in 2008 in some areas identified as 

potential, previously unsurveyed 

habitat, these did not result in any new 

locations of the species (Colket 2008, 

pp. 4-6). There have also been searches 

for L. papilliferum in eastern Oregon, 

but the species has never been found 

there (Findley 2003, p. 1). We have no 

historical records indicating that L. 

papilliferum has ever been found 

anywhere outside of its present range in 

southwestern Idaho, as described in this 

rule. 

Abundance and Population Trend 

Forming a reliable estimate of any 

trend in the abundance of Lepidium 

papilliferum over time is complicated 

by multiple factors. For one, since 

individuals of the species may act as 

either an annual or a biennial, in any 

given year there will be varying 

numbers of plants acting as springflowering annuals versus overwintering 

rosettes. The relative proportions of 

these two life history forms can 

fluctuate annually depending on a 

variety of factors, including 

precipitation, temperature, and the 

abundance of rosettes produced the 

previous year (Unnasch 2008, pp. 14-15; 

Sullivan and Nations 2009, pp. 43-44, 

134-135). Secondly, L. papilliferum has 

a long-lived seed bank, likely as an 

adaptation to unpredictable conditions, 

in which years of good rainfall favorable 

for germination and survival may be 

followed by periods of drought; a 

persistent seed bank provides a 

population buffer against years of poor 

reproductive potential in such a highly 

variable environment (Meyer et al. 2005, 

p. 21). Only a small percentage of L. 

papilliferum seeds germinate annually, 

resulting in an estimated maximum 

longevity of 12 years for seeds in the 

seed bank (Meyer et al 2005, p. 18). The 

presence of this persistent seed bank 

confounds the ability to determine any 

trend in abundance over time, as the 

number of above-ground plants that can 

be counted in any one year represents 

only a subset of the latent population 

that is present in the seed bank. In 

effect, it takes at least 12 years to trace 

the fate of a single year’s cohort of 

seeds, resulting in a significant lag effect 

in detecting any real underlying change 

in total population abundance over the 

long term. 

An additional complicating factor in 

trying to detect any population trend for 

Lepidium papilliferum is the extreme 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52023 

variability of annual abundance or 

density of the plant. As is common for 

desert annuals, the numbers of L. 

papilliferum can vary dramatically from 

year to year, depending on 

environmental conditions. As an 

example, the total number of plants on 

the 16 special-use plots at the OTA went 

from 624 individuals in 1997 to 3,330 

plants in 1998, subsequently dropping 

back down again to 756 plants in 1999; 

total abundance over the years 1991 

through 2008 ranged from a low of 249 

plants to 15,236 individuals (Weaver 

2008). Some of the great variation in 

yearly plant numbers is likely due to the 

relationship between L. papilliferum 

and precipitation, as described above. 

The annual abundance or density of L. 

papilliferum shows a significant 

positive association with levels of 

spring rainfall, roughly from March 

through May (Meyer et al. 2005, p. 15; 

Palazzo et al. 2005, p. 9; Sullivan and 

Nations 2009, pp. 39-41), and survival 

of potential biennials is associated with 

increased summer rainfall (Meyer et al. 

2005, p. 15). There is also some 

suggestion that increased winter 

precipitation may show a negative 

association with plant abundance, 

although not all analyses are 

consistently significant on this point 

(Meyer et al. 2005, pp. 15-16; Sullivan 

and Nations 2009, pp. 39-41). 

Temperature also appears to play a role 

in annual abundance of L. papilliferum 

in concert with precipitation, although 

the exact nature of the relationship is 

complex and not well understood 

(Sullivan and Nations 2009, p. 57). 

Furthermore, the interaction between 

temperature, precipitation, and L. 

papilliferum abundance appears to vary 

regionally between the Boise Foothills, 

Owyhee Plateau, and Snake River Plain 

(Sullivan and Nations 2009, pp. 103- 

104). 

Because the population dynamics of 

Lepidium papilliferum are complicated, 

surrogate methods of monitoring the 

status of the species, such as monitoring 

the status of the ecosystem upon which 

it depends, may be preferable to counts 

of individual plants. For example, due 

to the extreme annual fluctuations in 

annual plant abundance and the 

complicating nature of the long-lived 

seed bank for this species, Mancuso and 

Moseley (1998, p. 1) note that 

‘‘estimating the number of above-ground 

plants is by itself not a reliable measure 

to evaluate population and species 

viability.’’ As an alternative or 

supplement to population monitoring, 

they suggest monitoring the ecological 

integrity of L. papilliferum habitat, 

essentially using measures of habitat 

quality and quantity as a surrogate for 

assessing the status or viability of L 

papilliferum. Habitat monitoring is a 

recommended method of monitoring 

annual plants with a long-lived seed 

bank, where in some years the majority 

of the plant population is expressed in 

the seed bank rather than as aboveground plants (Elzinga et al. 1998, p. 

55). For these reasons, we consider that 

data regarding the trends in habitat 

quality and quantity for L. papilliferum 

provide us with information that is 

equally important, if not more so, than 

direct counts of individual plants in 

evaluating the overall status of the 

species. Trends in habitat quality are 

discussed in the Habitat Quality section 

of this document, as well as under The 

Present or Threatened Destruction, 

Modification, or Curtailment of Its 

Habitat or Range in the Summary of 

Threats Affecting the Species section, 

below. 

From a statistical standpoint, the 

extreme variability in annual abundance 

or density estimates greatly reduces the 

ability to reliably detect a long-term 

trend in the population without many 

years of standardized data. The presence 

of the persistent seed bank adds further 

uncertainty to the determination of 

population trend, as 12 years may 

effectively be considered to represent a 

single generation of the plant. Relatively 

short-term analyses of abundance 

estimates for the purposes of estimating 

a population trend are thus of limited 

utility due to the high variance observed 

in the data (Sullivan and Nations 2009, 

p. 93). In our evaluation, we weighed 

the relative quality of the available 

datasets for discerning population trend 

in Lepidium papilliferum according to 

the degree of confidence we had in the 

results of any analyses, given the great 

degree of variability observed and the 

multiple factors potentially influencing 

annual counts of the plant. 

Four data sets are available that 

provide some index or measure of 

Lepidium papilliferum abundance: 

Rangewide EO records, rangewide HII– 

HIP transects, rough census data 

collected on the OTA, and special-use 

plot data from the OTA. Each of these 

programs is described in the Monitoring 

of Lepidium papilliferum 

Populations section, above, and the 

degree to which we relied on the 

information provided by them is 

described below. 

The INHP records of Lepidium 

papilliferum EOs provide only 

estimated ranges or categorical estimates 

of abundance, and are so variable in 

both size and space over time that we 

considered these records to be 

informative in terms of evaluating the 

current overall condition of the species, 

but we did not rely on EO records for 

temporal population trend estimates. 

Five years of HII monitoring data 

(1998 to 2002) and 5 years of HIP 

monitoring data (2004 to 2008) are 

available on Lepidium papilliferum 

abundance and habitat condition 

rangewide. Although the HII–HIP 

program provides valuable information 

regarding the relationship between L. 

papilliferum abundance and measures 

of habitat quality or disturbance, the 

time series of this data set is considered 

too short to reliably detect any trend in 

rangewide population abundance, due 

to the extreme annual variability in the 

data (Sullivan and Nations 2009, p. 93). 

We consider the best available data 

regarding Lepidium papilliferum 

abundance to be the long-term datasets 

from the OTA, including the rough 

census areas and special-use plots, 

which provide 18 years of population 

monitoring information. The relative 

value of the OTA dataset is supported 

by the analysis of Sullivan and Nations 

(2009), a report resulting from our 

contract with an independent 

consulting firm to evaluate the available 

population trend data for L. 

papilliferum, as well as to analyze any 

information available regarding 

potential relationships between the 

abundance of L. papilliferum and 

measures of habitat quality or 

disturbance. Considering the available 

data from the HII–HIP monitoring, and 

the rough census area and special-use 

plot monitoring from the OTA, Sullivan 

and Nations considered that the longterm nature of the datasets from the 

OTA make these data the best available 

data when attempting to model trends 

through time (Sullivan and Nations 

2009, p. 56). Furthermore, they placed 

slightly greater confidence in the 

analyses based on the rough census 

areas as opposed to the special-use 

plots, since the special-use plots are in 

effect a subset of the rough census areas 

and are based on counts from only a 

single slickspot, and are therefore 

subject to greater variability in response 

to localized impacts (Sullivan and 

Nations 2009, pp. 55, 96). They also 

noted that the HII and HIP programs do 

not yet have sufficient data to determine 

population trends rangewide (Sullivan 

and Nations (2009, p. 93). However, 

they determined that all three 

programs—rangewide HIP, OTA rough 

census areas, and OTA special-use 

plots— track annual changes in L. 

papilliferum abundance similarly, and 

each can act as an index of abundance. 

Based on their analysis, they concluded 

that the trend observed on the OTA may 

be considered likely representative of 


srobinson on DSKHWCL6B1PROD with RULES4
52024 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

the trend across the entire range of the 

species (Sullivan and Nations 2009, p. 

96). 

Analysis of Population Trend 

Sullivan and Nations analyzed the 

data on Lepidium papilliferum numbers 

(density or total abundance) from both 

the rough census areas and the specialuse plots at the OTA, assuming a simple 

linear trend and using a repeated 

measures implementation of the general 

negative binomial regression model to 

account for the large variances in the 

data (a statistical technique for 

determining whether a statistically 

significant trend exists when using a 

data set with counts from the same areas 

every year and large changes in the 

values between years). The model was 

not intended to describe the complex 

pattern in the relative density or 

abundance of L. papilliferum over time, 

but only to determine whether there is 

evidence of any overall population 

trend (Sullivan and Nations 2009, p. 

38). 

Based on this model, of the two OTA 

datasets, Sullivan and Nations (2009, 

pp. 3, 55, 96) considered the rough 

census data to be slightly more reliable. 

Their analysis of this rough census data 

showed a negative trend in density with 

a slope of -0.086 over the years 1990 to 

2008; this trend was statistically 

significant (p = 0.0087, two-sided pvalue) (Sullivan and Nations 2009, pp. 

38-39). Because plant density was 

unusually high on a single rough census 

area, the Study 4 Site, the data were 

reanalyzed, removing that site as a 

potentially highly influential data point. 

The result was a more shallow negative 

slope (-0.059), but the trend remained 

statistically significant (p = 0.0046) 

(Sullivan and Nations 2009, p. 39). 

Rough census area densities were 

further regressed against 3–month 

running averages of precipitation. 

Lepidium papilliferum density was 

positively associated with mean 

monthly precipitation in each of the 

January to March, February to April, 

and March to May periods, and 

negatively associated with mean 

monthly precipitation for the periods 

October to December, November to 

January, and December to February; 

these relationships were all significant 

at p < 0.0001 (Sullivan and Nations 

2009, pp. 39-40). These findings are 

consistent with those of Meyer et al. 

2005 (pp. 15-16), which reported a 

positive association between Lepidium 

seedlings recruited and spring 

precipitation, and a likely negative 

association with winter precipitation, 

which is postulated to drown 

overwintering rosettes. 

The analysis of abundance data from 

the special-use plots on the OTA reveals 

a similarly negative slope over the years 

1991 through 2008, but the results were 

not statistically significant (p = 0.2857) 

(Sullivan and Nations 2009, p. 4). In 

other words, based on the count data 

from the special-use plots, there was not 

sufficient evidence to conclude that the 

slope of abundance over time was 

significantly different from zero. The 

relationship between abundance and 

spring precipitation on the special-use 

plots was similar to that observed on the 

rough census areas; mean monthly 

precipitation in January to March, 

February to April, and March to May 

were all positively associated with 

abundance and all were statistically 

significant (p < 0.0001). There was no 

significant relationship, however, 

between fall or winter precipitation and 

Lepidium papilliferum abundance on 

the special-use plots (Sullivan and 

Nations 2009, p. 41). Using a shorter 

time-series of data from 2000 to 2008, 

Sullivan and Nations (2009, pp. 43-44) 

found that the abundance of blooming 

plants was positively associated with 

both the current year’s precipitation and 

the number of rosettes present in the 

previous year, and that the number of 

rosettes was negatively associated with 

precipitation in the prior October to 

December period. 

The researchers concluded that there 

is ‘‘limited evidence for declining 

populations,’’ because trends on the 

OTA are negative but only statistically 

significant for the rough census areas 

(Sullivan and Nations 2009, pp. 2, 44). 

In earlier analyses of Lepidium 

papilliferum population HII–HIP data, 

Menke and Kaye had initially reported 

a negative rangewide population trend 

for the periods 1998 through 2002 

(Menke and Kaye 2006a) and for 1998 

through 2004 (Menke and Kaye 2006b). 

However, Sullivan and Nations (2009, p. 

141) point out that the fact that the HII 

transects were first monitored during a 

higher-than-average abundance year in 

1998 greatly influenced the 

interpretation of the short time-series 

dataset, and suggest that the negative 

trend in abundance is not supported 

when abundance in subsequent years is 

included. Additionally, as described 

above, the HII–HIP data collection has 

not yet occurred over a long enough 

period to allow for reliable trend 

analyses (Sullivan and Nations 2009, p. 

93). In comparing the mean number of 

L. papilliferum per transect resulting 

from his own analyses of HIP data from 

2005 through 2007 with the results 

reported by Menke and Kaye (2006b), 

Unnasch (2008, p. 14) suggests that, 

since 1999, there has been no consistent 

rangewide population trend for the 

species. 

Although Sullivan and Nations did 

not attempt to discern a trend in 

population numbers based on the HIP 

data, they did compare mean total 

abundance of Lepidium papilliferum per 

transect between physiographic regions, 

based on the HIP data from 2004 

through 2008. They found that relative 

abundance was significantly different 

between regions, being greatest in the 

Boise Foothills region and lowest on the 

Owyhee Plateau region; abundance on 

the Snake River Plain region was 

intermediate between the other two 

(Sullivan and Nations 2009, p. 103). 

In summary, we have reviewed all of 

the best available scientific and 

commercial data available to us to 

determine whether we can discern a 

long-term trend in the abundance of 

Lepidium papilliferum. The extreme 

variability in annual counts of the 

species makes it difficult to discern a 

trend in numbers with statistical 

confidence. For this reason, we place 

greater confidence in the longest time 

series of monitoring data available to us, 

that from the OTA (up to 18 years of 

data for some rough census areas and all 

special-use plots). In addition, as 

described above, Sullivan and Nations 

suggest that the data from the rough 

census areas may be considered slightly 

more reliable than that from the specialuse plots (Sullivan and Nations 2009, 

pp. 3, 55). The long-term data from the 

OTA, which we considered to be the 

best available data for attempting to 

model trends through time in agreement 

with Sullivan and Nations (2009, pp. 3, 

56), suggest that population numbers 

may be trending downward on the OTA. 

Although numbers on both the rough 

census areas and the special-use plots 

showed a slightly negative slope over 

time, only the analysis of the rough 

census areas was statistically significant 

(Sullivan and Nations 2009, pp. 38-40). 

We considered this to be relatively 

limited evidence of a downward trend 

in the population, given the lack of 

consistently significant results between 

the two monitoring programs. 

Furthermore, the slope is not steep, 

annual variation in plant numbers 

continues to be extremely high, and the 

plant has demonstrated an ability to 

rebound from low numbers due to the 

persistent seed bank. 

We do recognize, however, that the 

OTA provides some of the highest 

quality habitat remaining for Lepidium 

papilliferum. Therefore, we believe it is 

reasonable to infer that if the population 

is trending downward there, then 

conditions are likely worse in the 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52025 

remainder of the plant’s range where 

habitat conditions are more degraded. 

This conclusion is supported by the 

analysis of Sullivan and Nations (2009, 

p. 96), which suggests that the trends on 

the OTA, as a general index of 

abundance, might reasonably be 

considered representative of trends 

rangewide (Sullivan and Nations 2009, 

p. 96). Direct evidence in support of this 

argument, however, is lacking. In 

addition, since the abundance of L. 

papilliferum is associated with annual 

precipitation, we considered whether 

any trend in precipitation over the same 

time period for which the rough census 

areas and special-use plot data were 

collected might be correlated with the 

observed negative trend in plant 

numbers. Assuming a simple linear 

trend, analogous to the model used by 

Sullivan and Nations in their analysis of 

L. papilliferum density and abundance 

at the OTA over time, we found no 

significant trend in precipitation at the 

OTA over the years 1991 through 2007 

(data were not available for 2008). 

Although we evaluated total annual 

precipitation, total and mean winter 

precipitation, total and mean spring 

precipitation, and 3–month moving 

averages across the year, least squares 

regression did not yield any slopes of 

precipitation over time that were 

statistically significant from zero 

(Zwartjes 2009, p. 1). Any observed 

negative trend in L. papilliferum density 

or abundance at the OTA thus appears 

to be independent of any trend in 

precipitation over the time period of 

interest. 

In weighing all of this information, we 

conclude that the best available 

evidence suggests that Lepidium 

papilliferum numbers may be trending 

downward. The dataset from the rough 

census areas on the OTA shows a 

significant downward trend in density 

over the last 18 years. Furthermore, we 

believe it is reasonable to infer that this 

negative trend may be similar or 

possibly even greater rangewide in areas 

outside the high quality habitat of the 

OTA, and this trend appears to be 

independent of any trend in 

precipitation. The best available 

scientific and commercial data therefore 

suggest that over the past two decades, 

L. papilliferum has likely significantly 

declined in abundance. 

In terms of projecting this trend into 

the future, however, there are many 

uncertainties associated with both the 

data and the model that preclude our 

ability to do so; these include, but are 

not limited to: Great annual variability 

in plant numbers, the confounding 

influence of the long-lived seed bank, 

the complications associated with 

annual variability in both precipitation 

and temperature, and the inconsistent 

results between the special-use plots 

and the rough census areas on the OTA. 

The evaluation of Sullivan and Nations 

was based on a simple model of 

Lepidium papilliferum abundance or 

density as a linear function of time, and 

intended only to discern whether there 

was any general trend in the population. 

The authors acknowledge that the 

dynamics are complicated, and note 

their model is not intended to describe 

(nor explain) the details of the temporal 

pattern of abundance or density of L. 

papilliferum (Sullivan and Nations 

2009, p. 38). In addition, we do not have 

any models for L. papilliferum based on 

multivariate analyses, which would 

simultaneously take into account 

additional variables such as 

precipitation, to potentially allow for 

the prediction of abundance or density 

of L. papilliferum over time based on 

projected conditions. Although the 

currently available model is helpful in 

terms of interpreting the population 

information available to date and 

indicates that L. papilliferum has likely 

been trending downward, for all of the 

reasons outlined above, it would be 

inappropriate to rely on this model to 

predict any future population trajectory 

for L. papilliferum. 

Habitat Quality 

As described above under ‘‘Ecology 

and Habitat,’’ the natural sagebrushsteppe community that surrounds the 

slickspot microsites in which Lepidium 

papilliferum occurs is dominated by 

sagebrush (primarily Artemisia 

tridentata ssp. wyomingensis) with a 

diverse understory of native perennial 

bunchgrasses and forbs. Historically, 

fires were relatively infrequent in this 

ecosystem, likely occurring on the order 

of every 100 years (Whisenant 1990, p. 

4). Data on the plant community and 

fire history pattern are some of the 

habitat quality attributes collected as 

part of Lepidium papilliferum HIP 

monitoring, which has been conducted 

rangewide since 2004. Results from the 

2008 HIP monitoring conducted at 80 

HIP transects indicated that over the 

past 5 years, 14 of the transects (18 

percent) that were initially 

characterized by predominantly native 

vegetation have undergone overall 

declines in habitat quality, primarily 

due to increased nonnative species 

cover (Colket 2009, pp. 10). 

Furthermore, this increase in nonnatives 

was observed not only in the 

surrounding plant community, but in 

the slickspots occupied by L. 

papilliferum as well. Bromus tectorum 

was the most common nonnative 

species in slickspots, followed by 

Agropyron cristatum (crested 

wheatgrass), Ceratocephala testiculata, 

formerly Ranunculus testiculatus (bur 

buttercup), and Lepidium perfoliatum 

(clasping-leaf pepperweed) (ICDC 2008, 

p. 9). Noxious or aggressive nonnatives 

detected in HIP transect slickspots 

include Linum perenne (‘Appar’ blue 

flax), Centaurea cyanus (garden 

cornflower), Bassia prostrata (prostrate 

kochia or forage kochia), Chondrilla 

juncea (rush skeletonweed), and 

Cardaria draba (whitetop) (Colket 2009, 

pp. 8-9). 

A review of the rangewide HIP 

transect data for evidence of fire history 

reveals that 38 of 80 HIP transects (48 

percent) currently show no effects from 

wildfire and 6 others (7.5 percent) were 

predominantly unburned. Five transects 

(6.25 percent) had partially burned 

(with approximately half of the area 

unburned), 13 (16.25 percent) were 

predominantly burned, and 18 (22.5 

percent) have completely burned 

(Colket 2009, Table 5). HIP classifies 

areas as burned if they are devoid of 

shrub cover or have patchy shrub cover 

in areas that exhibit the site capacity to 

support a healthy sagebrush-steppe 

community; this may include areas that 

have recently or historically burned. 

Four HIP transects were burned in 2007 

in the Murphy Complex Fire in the 

Owyhee Plateau geographic region 

(Colket 2009, p. 23). Sixty-six of the 80 

HIP transects (83 percent) have nearby 

wildfire effects within 1,640 ft (500 m) 

(Colket 2009, p. 26). A recent geospatial 

data analysis evaluating the total 

Lepidium papilliferum EO area affected 

by wildfire from 1957 to 2007 found 

that the perimeter of 107 wildfires that 

had occurred encompassed 

approximately 11,442 ac (4,509 ha), or 

73 percent of the total EO area 

rangewide (Stoner 2009, p. 48). 

However, caution should be used in 

interpreting this geospatial information, 

as this represents relatively coarse 

vegetation information that may not 

reflect that some EOs may be located 

within remnant unburned islands of 

sagebrush habitat within fire perimeters. 

Several features of slickspots and 

their surrounding habitat were 

consistently more degraded in areas that 

had burned. Slickspots in burned areas 

had lower soil crust cover and greater 

exotic (nonnative) species cover, and 

the total native species cover and shrub 

cover were consistently lower in burned 

transects, while total exotic species 

cover,, including Bromus tectorum, was 

consistently higher in burned transects 

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

and Nations (2009, p. 3) found a 

significantly negative relationship 


srobinson on DSKHWCL6B1PROD with RULES4
52026 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

between the abundance or density of 

Lepidium papilliferum and both the 

presence of B. tectorum and past fire. 

The positive association between the 

abundance of B. tectorum and fire 

frequency is well established 

(Whisenant 1990, p. 6). The complex 

and positive feedback loop between the 

encroachment of invasive annual 

grasses such as B. tectorum, increased 

fire frequency, and decreased integrity 

of biological soil crusts contributes to 

the degradation of sagebrush-steppe 

habitat quality for L. papilliferum (for 

additional details, see the Modified 

Wildfire Regime and Invasive Nonnative 

Plant Species discussions under Factor 

A of Summary of Factors Affecting the 

Species). 

Element Occurrences Rangewide 

The EO ranking system utilized by the 

INHP is described above in the 

Monitoring of Lepidium papilliferum 

Populations section. In brief, 

occurrences of Lepidium papilliferum 

are ranked based on measures of habitat 

quality and species abundance. The first 

EO ranks for L. papilliferum were 

assigned in 1993 (Colket et al. 2006, 

Tables 1-13). In 2006, L. papilliferum 

EO specifications and ranking were 

updated and revised by the ICDC to 

apply more consistent EO specifications 

rangewide (Colket et al. 2006, pp. 15- 

44). Due to the change in methods in 

2006, EO rankings assigned before 2006 

are not comparable to those assigned 

after 2006. Currently, EO ranks are more 

consistently assigned, are useful as an 

assessment of estimated viability or 

probability of persistence, and help 

prioritize conservation planning or 

actions (NatureServe 2002). 

As of February 2009, the INHP has 

ranked 80 extant EO records for 

Lepidium papilliferum based on habitat 

quality and abundance (Cole 2009b, 

Threats Table). In addition, nine EOs are 

ranked as extirpated or probably 

extirpated, and seven EOs are 

considered historical (information is too 

vague for relocation of the sites). All 

nine extirpations were formerly verified 

locations from old herbarium 

collections (the most recent from 1955) 

where the habitat is now completely 

developed or converted to agricultural 

lands (Colket et al. 2006, Table 13). The 

80 extant (as of February 2009) EOs 

represent a reduction in the number of 

extant EOs (85) known in 2006. 

However, this reduction in the number 

of EOs is due to the merging of EOs 

associated with new locations of plants 

rather than from the loss of individual 

EOs. As of February 2009, there are no 

A-ranked EOs for L. papilliferum; the 

most common EO ranks for L. 

papilliferum rangewide are C and D 

(Table 2). EO ranks also vary by 

physiographic region. A little more than 

one-half of the extant EO area in the 

Boise Foothills region is ranked as C, 

which means there are 50 to 399 aboveground plants, low to moderate 

introduced nonnative plant species 

cover, and EOs are partially burned. 

Approximately three-quarters of the 

total EO area in the Snake River Plain 

is ranked B, meaning there are 400 to 

999 above-ground plants, the native 

plant community is intact with low 

introduced nonnative plant species 

cover, and EOs are largely unburned. 

The majority of the B-ranked EO acreage 

rangewide occurs on the Idaho Army 

National Guard’s Orchard Training Area 

(OTA). The majority of the total EO area 

in the Owyhee Plateau physiographic 

region is also ranked B. 

EO size can also influence the ranking 

of an EO as a percentage of total 

rangewide EO area. For example, one 

EO (number 27) located on the OTA in 

the Snake River Plain region has a total 

area of 7,163 acres (2,899 ha) and 

accounts for roughly 59 percent of all 

the area within Lepidium papilliferum 

EOs assigned a B rank throughout the 

entire range of the species. There are 

less than 2.2 ac (1 ha) of B-ranked area 

in the Boise Foothills region, and nearly 

2,540 B-ranked ac (1,028 ha) on the 

Owyhee Plateau. Therefore, according to 

the EO rankings, the majority of the 

highest quality remaining habitat for L. 

papilliferum occurs on the Snake River 

Plain (see Table 2), with most of that 

occurring within the OTA. 

TABLE 2. EXTANT ELEMENT OCCURRENCE (EO) RANKS ACROSS THE ENTIRE RANGE OF Lepidium papilliferum 

(INHP data from February 2009). 

Element Occurrence Rank No. EO’s Hectares Acres Percent of Area 

Boise Foothills 

B 1 0.84 2.07 1.65 

BC 1 1.79 4.41 3.53 

C 5 28.34 70.03 56.05 

D 6 15.37 37.99 30.40 

F 3 4.23 10.46 8.37 

TOTAL 16 50.57 124.96 100.00 

Snake River Plain 

B 5 3,875.14 9,575.47 73.77 

BC 1 1.42 3.51 0.03 

C 19 935.06 2,310.53 17.80 

D 12 350.44 865.94 6.67 

D? 1 0.78 1.93 0.01 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52027 

TABLE 2. EXTANT ELEMENT OCCURRENCE (EO) RANKS ACROSS THE ENTIRE RANGE OF Lepidium papilliferum— 

Continued 

(INHP data from February 2009). 

Element Occurrence Rank No. EO’s Hectares Acres Percent of Area 

F 4 89.82 221.94 1.71 

NR 1 0.20 0.48 0.00 

TOTAL 43 5,252.86 12,979.81 100.00 

Owyhee Plateau 1

B 5 1,027.50 2,537.00 96.02 

C 4 21.85 53.99 2.04 

D 5 18.42 45.52 1.72 

E 0 0.00 0.00 0.00 

F 7 2.36 5.83 0.22 

TOTAL 21 1070.13 2,644.35 100.00 

1 Note that Sullivan and Nations (2009, pp. 79-81) differed in their overview of extant EOs in the Owyhee Plateau as they presented EO 16 as 

each of its 27 individual sub-EOs (sub-EOs 700-726). Table 2 combines all Owyhee Plateau sub-EOs into the single EO 16 and also incorporates changes as described in the February 2009 INHP Lepidium papilliferum data. 

Summary of Factors Affecting the 

Species 

Section 4 of the Act and its 

implementing regulations (50 CFR 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: (A) The present or 

threatened destruction, modification, or 

curtailment of its habitat or range; (B) 

overutilization for commercial, 

recreational, scientific, or educational 

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

the inadequacy of existing regulatory 

mechanisms; or (E) other natural or 

manmade factors affecting its continued 

existence. Listing actions may be 

warranted based on any of the above 

threat factors, singly or in combination. 

Each of these factors relevant to 

Lepidium papilliferum is discussed 

below. 

A. The Present or Threatened 

Destruction, Modification, or 

Curtailment of Its Habitat or Range 

Several threat factors are contributing 

to the destruction, modification, or 

curtailment of Lepidium papilliferum’s 

habitat or range. The sagebrush-steppe 

habitat of the Great Basin where L. 

papilliferum occurs is becoming 

increasingly degraded due to the 

impacts of multiple threats, including 

the invasion of nonnative annual 

grasses, such as Bromus tectorum, and 

increased frequency of fire. As 

described below, B. tectorum can 

impact L. papilliferum directly through 

competition, but also indirectly by 

providing continuous fine fuels that 

contribute to the increased frequency 

and extent of wildfires. Frequent 

wildfires have numerous negative 

consequences in the sagebrush-steppe 

system, which is adapted to much 

longer fire-return intervals, ultimately 

resulting in the conversion of the 

sagebrush community to nonnative 

annual grasslands, with associated 

losses of native species diversity and 

natural ecological function. Because the 

modified wildfire regime and invasion 

of B. tectorum create a positive feedback 

loop, it is difficult to separate out the 

effects of each of these threat factors 

independently. We have attempted to 

do so here, but much of the discussion 

may overlap due to the inherent 

synergism between these two threat 

factors. 

In addition to wildfire and nonnative 

plants, development poses a threat to 

Lepidium papilliferum, both directly 

through the destruction of populations 

and loss of slickspot microsites, and 

indirectly through habitat fragmentation 

and isolation (discussed separately 

under Factor E, below). The loss of 

slickspots is a permanent loss of habitat 

for L. papilliferum, since the species is 

specialized to occupy these unique 

microsite habitats that were formed in 

the Pleistocene, and once lost, 

slickspots cannot be recreated on the 

landscape. 

Livestock pose a threat to Lepidium 

papilliferum, primarily through 

mechanical damage to individual plants 

and slickspot habitats. However, the 

current livestock management 

conditions and associated conservation 

measures address this potential threat 

such that it does not pose a significant 

risk to the viability of the species as a 

whole. 

All of these threats have long been 

recognized as contributing to the 

ongoing degradation of the sagebrushsteppe ecosystem of southwestern 

Idaho. However, we have only recently 

received independent evaluations of the 

direct relationship between the more 

significant threats and indicators of 

population viability specifically for 

Lepidium papilliferum. New evidence 

suggests that there is a significant 

negative association between cover of 

nonnative plant species and wildfire 

and the abundance of L. papilliferum, 

such that the species appears to be in 

decline across its range, with adverse 

impacts continuing and likely 

increasing into the foreseeable future. 

Each of the threat factors contributing to 

the present or threatened destruction, 

modification, or curtailment of L. 

papilliferum’s habitat or range is 

assessed in detail below. 

Modified Wildfire Regime 

Fire was historically infrequent in the 

desert shrublands of the Great Basin, as 


srobinson on DSKHWCL6B1PROD with RULES4
52028 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

the native plant communities of the 

native annuals and bunchgrasses did 

not provide sufficient fine fuels to carry 

large scale wildfires. The bare spaces 

between widely spaced shrubs and 

relatively low fuel loads in such 

ecosystems as the sagebrush-steppe 

generally prevented fires from spreading 

very far, and any fires that did burn 

were usually restricted to relatively 

small, isolated patches (Brookes and 

Pyke 2001, p. 5; Whisenant 1990, pp. 4, 

6). Natural fire return intervals in 

sagebrush-steppe prior to the arrival of 

European settlers are estimated to have 

ranged from 60 to 110 years; the 

estimate for the more xeric Artemisia 

tridentata ssp. wyomingensis sagebrush 

community inhabited by Lepidium 

papilliferum is estimated to have been 

as long as 100 years (Wright and Bailey 

1982, p. 158) and possibly up to 240 

years (Baker 2006, p. 181). Beginning in 

the early 1900s, however, the 

widespread invasion of nonnative plant 

species, particularly annual grasses such 

as Bromus tectorum and Taeniatherum 

caput-medusae, has created a bed of 

continuous fine fuels across the 

southwest Idaho landscape. The 

continuous fine fuels provided by these 

nonnative annual grasses result in more 

frequent fires due to greater horizontal 

fuel continuity, increased fuel surfaceto-volume ratio, and various properties 

that facilitate wildfire ignition, such as 

lower moisture content and thus 

increased flammability (Whisenant 

1990, p. 6; Pellant 1996, p. 3 and 

references therein; Brooks et al. 2004a, 

p. 679). Nonnative annual grasses also 

provide for more continuous and 

uniform fires, burning across extensive 

areas of the landscape. Native 

bunchgrasses provide a patchy, 

discontinuous fuelbed such that fires 

are not easily carried and tend to burn 

only in small patches. The continuous 

fires carried by nonnative annual 

grasses such as B. tectorum, on the other 

hand, leave few or no patches of 

unburned vegetation, which can inhibit 

the post-fire recovery of native 

sagebrush-steppe vegetation by 

eliminating seed sources for regrowth of 

the native species (Whisenant 1990, p. 

4; Pyke 2007). Bromus tectorum, in 

particular, apparently alters the soil 

environment such that it creates a 

positive feedback loop, enhancing the 

environment for its own growth and 

generating conditions conducive to 

further invasion (Pyke 2007). As B. 

tectorum has become more dominant in 

the sagebrush-steppe habitat of the 

Snake River Plain over the past several 

decades, wildfire frequency intervals 

have become shortened from the 

historical average of 60 to 110 years to 

the current frequency intervals of 5 

years or less (Wright and Bailey 1982, p. 

158; Billings 1990, pp. 307-308; 

Whisenant 1990, p. 4; USGS 1999; West 

and Young 2000, p. 262; Launchbaugh 

et al. 2008, p. 3; Zouhar et al. 2008, pp. 

40-41). 

The dramatic increase in the 

frequency of wildfires has a particularly 

negative effect on the native plant 

community in this region that has 

historically experienced fire relatively 

infrequently, and thus is dominated by 

plants that are not adapted to short firereturn intervals. Many of the native 

species of the sagebrush-steppe 

ecosystem are killed outright by 

wildfires and do not have adaptations 

such as underground rhizomes for postfire vegetative regrowth, but must 

reproduce by seed. As a result, under a 

regime of increasingly frequent fire, 

perennial plants tend to be lost from the 

landscape (Whisenant 1990, p. 9). 

Sagebrush (Artemisia spp.), for example, 

are easily killed by fire (Baker 2006, p. 

178 and references therein; Cooper et al. 

2007, p. 8; USDA Forest Service Fire 

Effects Information System 2009). 

Because they are not adapted to frequent 

fires, sagebrush does not resprout after 

burning, as many fire tolerant species do 

(Young and Evans 1978, pp. 283, 287; 

Brooks and Pyke 2001, pp. 6-7; USDA 

Forest Service Fire Effects Information 

System 2009), but must rely upon seed 

sources for reestablishment. Natural 

revegetation requires a nearby remnant 

seed source, as from an unburned patch 

of sagebrush, which now rarely occurs 

because of the more continuous and 

extensive fires that occur if a B. 

tectorum understory is present (USDA 

Forest Service Fire Effects Information 

System 2009). In addition, when fires 

occur as frequently as every 3 to 5 years, 

even if seedlings should begin to grow 

there is not sufficient time for sagebrush 

to regenerate prior to the next fire cycle. 

Thus, sagebrush is eliminated from the 

plant community, which in turn allows 

for conversion to annual grassland 

(Whisenant 1990, p. 9; Pyke 2007; 

USDA Forest Service Fire Effects 

Information System 2009). The short 

fire-return intervals now experienced in 

this region prevent the sagebrush-steppe 

community from recovering and 

attaining late seral stage condition, thus 

eliminating high quality habitat for L. 

papilliferum. 

The dramatic increase in frequency 

and extent of wildfires has contributed 

to the conversion of vast areas of 

sagebrush-steppe into invasive annual 

grasslands (USGS 1999). Since post-fire 

conditions are favorable for further 

invasion and establishment of nonnative 

annual grasses, invasive grasses soon 

dominate the community, leading to the 

establishment of an invasive grassincreased fire frequency cycle 

(Whisenant 1990, p. 4; Brooks and Pyke 

2001, p. 5; D’Antonio and Vitousek 

1992, pp. 73, 75; Brooks et al. 2004a, p. 

678). Invasive grasses promote recurrent 

fires, which in turn convert high 

diversity native shrublands to low 

diversity alien grasslands; these 

grasslands then burn more frequently 

and expansively across the landscape, 

creating disturbance conditions that 

promote the further expansion of the 

invasive grasses, and so on. This 

invasive grass-fire cycle has been 

recognized in Great Basin shrub 

ecosystems since the 1930s (Brooks and 

Pyke 2001, p. 5, and references therein). 

As an example, at the Snake River Birds 

of Prey National Conservation Area in 

the Snake River Plain area of southern 

Idaho, nearly half of the native 

sagebrush-steppe habitat (a total of 

494,211 ac (200,000 ha)) converted to 

nonnative annual grasslands in less than 

10 years by a series of 200 fires (Smith 

and Collopy 1998, as cited in Brooks 

and Pyke 2001, p. 7). 

The rate of conversion from 

sagebrush-steppe to annual grasslands 

continues to accelerate in the Snake 

River Plain of southwest Idaho 

(Whisenant 1990, p. 4). As the coverage 

of Bromus tectorum continues to 

increase in the region, it is reasonable to 

expect that the extent and frequency of 

wildfires will likewise continue to 

increase, given the demonstrated 

positive feedback cycle between these 

factors (Whisenant 1990, p. 4; Brooks 

and Pyke 2001, p. 5; D’Antonio and 

Vitousek 1992, pp. 73, 75; Brooks et al. 

2004a, p. 678). Climate change models 

also project a likely increase in fire 

frequency within the semiarid Great 

Basin region inhabited by Lepidium 

papilliferum (see Climate Change under 

Factor E, below). 

Wildfire therefore contributes to the 

continuing invasion and establishment 

of nonnative annual grasslands within 

the range of Lepidium papilliferum, 

which in turn further increases the 

likelihood of more frequent and intense 

wildfires across the range of the species 

(Brooks et al. 2004a, pp. 677-687). But 

wildfire’s role in promoting the invasion 

of annual grasses goes beyond its 

circular positive impact on the fire 

cycle, as nonnative annual grasses and 

other nonnative plant species that are 

likely to invade following fire have 

numerous other negative effects on L. 

papilliferum, slickspots, and the 

surrounding sagebrush-steppe 

ecosystem as well, as described below 

under Invasive Nonnative Plant Species. 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52029 

Wildfire also damages biological soil 

crusts, which are important to the 

sagebrush-steppe ecosystem and 

slickspots where Lepidium papilliferum 

occur, because the soil crusts stabilize 

and protect soil surfaces from wind and 

water erosion, retain soil moisture, 

discourage annual weed growth, and fix 

atmospheric nitrogen (Eldridge and 

Greene 1994 as cited in Belnap et al. 

2001, p. 4; Johnston 1997, pp. 8-10; 

Brooks and Pyke 2001, p. 4). Fires can 

cause severe damage to soil crusts, 

altering their ecological function and 

creating an opportunity for invasion by 

weedy annual plant species (Johnston 

1997, p. 10; Brooks and Pyke 2001, p. 

4, and references therein). 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). In general, L. papilliferum 

abundance is greatest in areas that also 

have the greatest cover of soil crust 

(Boise Foothills and Snake River Plain), 

although the populations in the Owyhee 

Plateau contrasted in showing a slightly 

negative (but not statistically 

significant) relationship with soil crust 

cover (Sullivan and Nations 2009, p. 

135). Fire in the presence of shrubs, 

particularly sagebrush, tends to be 

greater in intensity, which decreases the 

potential for soil crust recovery 

(Johnston 1997, p. 11); therefore, 

recovery of these crusts after a fire is 

less likely in the sagebrush-steppe 

habitat where L. papilliferum occurs. 

Given the generally positive association 

between soil crust cover and L. 

papilliferum, the compromised integrity 

of the microbiotic crust in response to 

fire likely has a negative impact on L. 

papilliferum as well. 

More frequent wildfires also promote 

soil erosion and consequent 

sedimentation, as perennial grasses that 

normally limit erosion are eliminated in 

arid environments such as the 

sagebrush-steppe ecosystem (Bunting et 

al. 2003, p. 82). Increased sedimentation 

can result in a silt layer that is too thick 

for optimal Lepidium papilliferum 

germination (Meyer and Allen 2005, pp. 

6-7). Wind erosion following wildfire 

can also remove the top silt layer of 

slickspots, exposing the clay vesicular 

layer below, as observed at HIP transect 

721 following the 2007 Murphy 

Complex Fire (U.S. BLM 2007, p. 23). 

However, effects of the loss of the upper 

slickspot silt layer on L. papilliferum are 

not known. 

The threats of wildfire and nonnative 

invasive species working in concert are 

considered the predominant factor 

affecting Lepidium papilliferum, 

particularly its habitat quality. In a 

statistical analysis of HII data over 5 

years between 1998 and 2001, areas that 

had burned earlier in the study and 

were left with depleted shrub and soil 

crust did not recover (Menke and Kaye 

2006a, p. iii). Burned areas had less 

native plant cover, greater nonnative 

plant cover, increased slickspot 

perimeter compromise (the slickspot 

boundaries lose definition), and 

increased organic debris accumulation 

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

mentioned above, analysis of additional 

HII and HIP data from 1998 through 

2004 showed that burned areas had less 

soil crust cover and greater nonnative 

plant cover (Menke and Kaye 2006b, p. 

3). Past wildfires thus appear to have 

had a lasting negative impact on the 

plant community surrounding 

slickspots, including increased 

nonnative species cover and decreased 

soil crust cover (Menke and Kaye 2006b, 

p. 19). Although we recognized wildfire 

as one of the primary threats affecting 

the matrix habitat of L. papilliferum in 

our 2007 finding, at that time we did not 

have any data that directly tied wildfire 

with a negative impact on the species 

itself, as would be demonstrated, for 

example, by a corresponding decline in 

L. papilliferum abundance (72 FR 1622, 

1635; January 12, 2007). 

As discussed above, several 

researchers have noted signs of 

increased habitat degradation for 

Lepidium papilliferum, most notably in 

terms of exotic species cover and 

wildfire frequency (e.g., Moseley 1994, 

p. 23; Menke and Kaye 2006b, p. 19; 

Colket 2008, pp. 33-34), but only 

recently have analyses demonstrated a 

statistically significant negative 

relationship between the degradation of 

habitat quality, both within slickspot 

microsites and in the surrounding 

sagebrush-steppe matrix, and the 

abundance of L. papilliferum. Sullivan 

and Nations (2009, pp. 114-118, 137) 

found a consistent, statistically 

significant negative correlation between 

wildfire and the abundance of L. 

papilliferum across its range. Their 

analysis of 5 years of HIP monitoring 

data indicated that L. papilliferum 

‘‘abundance was lower within those 

slickspot (sic) that had previously 

burned’’ (Sullivan and Nations 2009, p. 

137), and the relationship between L. 

papilliferum abundance and fire is 

reported as ‘‘relatively large and 

statistically significant,’’ regardless of 

the age of the fire or the number of past 

fires (Sullivan and Nations 2009, p. 

118). The nature of this relationship was 

not affected by the number of fires that 

may have occurred in the past; whether 

only one fire had occurred or several, 

the association with decreased 

abundance of L. papilliferum was 

similar (Sullivan and Nations 2009, p. 

118). 

The evidence also points to an 

increase in the geographic extent of 

wildfire within the range of Lepidium 

papilliferum. Since the 1980s, 59 

percent of the total L. papilliferum 

management area acreage rangewide has 

burned, more than double the acreage 

burned in the preceding three decades 

(from the 1950s through 1970s). Based 

on available information, approximately 

11 percent of the total management area 

burned in the 1950s; 1 percent in the 

1960s; 15 percent in the 1970s; 26 

percent in the 1980s; 34 percent in the 

1990s; and as of 2007, 11 percent in the 

2000s (data based on GIS fire data 

provided by BLM Boise and Twin Falls 

District; I. Ross 2008, pers. comm. and 

A. Webb 2008, pers. comm., as cited in 

Colket 2008, p. 33). Based on the 

negative relationship observed between 

fire, L. papilliferum, and habitat quality 

as described above, we conclude that 

this increase in area burned translates 

into an increase in the number of L. 

papilliferum populations subjected to 

the negative impacts of wildfire. 

An evaluation of Lepidium 

papilliferum EOs for which habitat 

information has been documented (79 of 

80 EOs) demonstrates that most have 

experienced the effects of fire. Fifty-five 

of 79 EOs have been at least partially 

burned (14 of 16 EOs on the Boise 

Foothills, 30 of 42 EOs on the Snake 

River Plain and 11 of 21 EOs on the 

Owyhee Plateau), and 75 EOs have 

adjacent landscapes that have at least 

partially burned (16 of 16 EOs on the 

Boise Foothills, 39 of 42 EOs on the 

Snake River Plain, and 20 of 21 EOs on 

the Owyhee Plateau) (Cole 2009b, 

Threats Table). 

In 2008, 38 of the 80 HIP transects 

were unburned, 6 were predominantly 

unburned, 5 approximately half burned 

and half unburned, 13 were 

predominantly burned, and 18 were 

completely burned. Sixty-six HIP 

transects had been at least partially 

burned to within 1,500 ft (500 m) 

(Colket 2009, p. 26). In 2007, the Inside 

Desert Fire on the Owyhee Plateau 

burned 2,695 ac (1,041 ha) within 

Management Area 11, and the Elk 

Mountain Fire burned 11,868 ac (4,083 

ha) within Management Area 11; both 

fires were part of the 652,016 ac 

(263,862 ha) Murphy Complex Fire in 

the Owyhee Plateau region (Colket 2009, 

p. 65). In 2008, the first year of HIP 

monitoring following the fire was 

completed in the four transects 

(Transects 701, 711, 719, and 721) that 

burned in the Murphy Complex Fire 


srobinson on DSKHWCL6B1PROD with RULES4
52030 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

(Colket 2009, p. 24). All 10 slickspots at 

HIP transect 701 had been previously 

burned before being burned again in 

2007. At HIP transect 711, only 1 

slickspot had been previously burned, 

but 9 of its 10 slickspots were burned 

in the Murphy Complex Fire. HIP 

transects 719 and 721 were completely 

unburned high quality big sagebrush 

habitat before the Murphy Complex Fire 

burned all 10 slickspots at both HIP 

transects (Colket 2009, p. 24). 

A 2009 geospatial data analysis 

evaluating the total Lepidium 

papilliferum EO area affected by 

wildfire from 1957 to 2007 found that 

107 wildfires have occurred, the fire 

perimeters of which included 

approximately 11,442 ac (4,509 ha), or 

73 percent of the total EO area (Stoner 

2009, p. 48). 

Table 3 shows the evidence of 

wildfires documented through HIP 

rangewide transect monitoring in 2008 

and includes both recent and historical 

fires. Wildfire evidence can remain on 

the landscape for up to 20 years. 

TABLE 3. EVIDENCE OF WILDFIRE DOCUMENTED AT HIP TRANSECTS IN 2008 (COLKET 2009, TABLE 5, PP. 50-62). 

Physiogeographic Region Number of HIP transects 

at least partially burned 

Number of HIP transects 

not burned Total HIP transects 

Adjacent landscapes 

within 0.31 miles (500 

meters) of HIP 

transects either burned 

or partially burned 

Boise Foothills 7 3 10 10 

Snake River Plain 21 26 47 38 

Owyhee Plateau 14 9 23 19 

TOTAL 42 (52.5 percent) 38 (47.5 percent) 80 (100 percent) 67 (84 percent) 

The effects of fire disturbance and 

habitat degradation are evident in some 

of the earliest photographs of HII and 

HIP transects, which show habitats 

lacking shrubs and dominated by 

Bromus tectorum. However, 

photographs from the early 1990s of 

transects that had not burned prior to 

being established were comprised 

primarily of native Artemisia tridentata 

with a nonnative B. tectorum or 

Ceratocephala testiculata understory. 

As of 2008, 14 of 80 total HIP transects 

had changed from a higher to a lower 

habitat quality classification since 2004, 

or had been partially or completely 

burned (Colket 2009, pp. 8-9). The 

photographs demonstrate that many of 

the transects that burned are now 

devoid of A. tridentata and are instead 

dominated by B. tectorum (Colket 2009, 

pp. 63-64). 

At present, ongoing control efforts 

may slow the incidence of wildfire in 

some areas, but are not capable of 

preventing wildfires across the range of 

Lepidium papilliferum. For example, 

four established HIP transects on the 

Owyhee Plateau burned in 2007 in the 

Inside Desert and Murphy Complex 

fires, even though wildfire control 

measures were in place and 

implemented (Colket 2009, p. 24). In the 

Snake River Plain region, portions of 

two EOs (EO 32, EO 26) were burned in 

2006 by the Ten York Fire and Cold Fire 

respectively. No EOs or portions of 

known EOs are documented to have 

burned in the Snake River Plain and 

Boise Foothills regions in 2007 (U.S. 

BLM 2008a, p. 21). On the OTA, the 

IDARNG has demonstrated intensive 

management efforts implemented to 

suppress wildfire and using wildfirerehabilitation activities with minimal 

ground disturbance have been effective 

in reducing the threat of wildfire and 

the rate of spread of nonnative invasive 

species (for additional information, see 

Wildfire Management and Post-Wildfire 

Rehabilitation section below). However, 

such intensive management is currently 

concentrated within L. papilliferum EOs 

and is possible only within a limited 

range of L. papilliferum. This may 

explain why the highest quality habitat 

remaining is on the OTA, where the 

greatest infrastructure is in place to 

manage and control wildfires. 

Summary of Modified Wildfire Regime 

The observed increases in frequency 

and geographic extent of wildfires, the 

negative consequences for L. 

papilliferum and its habitat associated 

with the invasion of nonnative grasses 

and wildfire, the strong positive 

feedback loop between wildfire and 

conversion of sagebrush-steppe to 

annual grasslands, and the lack of 

effective rangewide control mechanisms 

all contribute to the current modified 

wildfire regime being the greatest 

ongoing threat to L. papilliferum’s 

existence. In addition, the best available 

data indicates that fire frequency is 

likely to increase in the foreseeable 

future due to increases in cover of B. 

tectorum and the projected effects of 

climate change (see Invasive Nonnative 

Plant Species, below, and also Climate 

Change under Factor E, below). Ongoing 

habitat loss and degradation is a result 

of the current wildfire regime, which is 

interrelated with several other negative 

factors, including: Increased nonnative 

species cover, especially annual grasses; 

increased sedimentation and organic 

debris accumulation in slickspots, 

which could alter slickspot function and 

hinder germination of L. papilliferum; 

the loss of native matrix vegetation, 

particularly shrubs; decreased native 

plant species diversity; decreased cover 

of microbiotic crusts; and habitat 

fragmentation due to isolation of habitat 

patches following fire. 

Given the observed negative 

association between the abundance of 

Lepidium papilliferum and the 

increased frequency of fire, as well as 

the demonstrated negative impacts of 

frequent fire on the components that 

normally provide high quality habitat 

for L. papilliferum, such as late seral 

stage sagebrush and high microbiotic 

crust cover, we consider the current 

wildfire regime to pose a significant 

threat to L. papilliferum. Recurrent fire 

promotes the continued invasion of 

nonnative annual grasses and other 

invasive nonnative plants, along with 

all of their associated negative effects 

(see Invasive Nonnative Plant Species 

below). Based on the observed increases 

in the cover of Bromus tectorum 

throughout the range of the species, the 

lack of effective control mechanisms, 

and projections under most climate 

change models, we expect the degree of 

this threat will continue and likely 

increase within the foreseeable future. 

The significant threat posed by the 

current modified wildfire regime is 

pervasive throughout the range of the 

species. 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52031 

Invasive Nonnative Plant Species 

Invasive nonnative plants have 

become established in Lepidium 

papilliferum habitats by spreading 

through natural dispersal (unseeded) or 

have been intentionally planted as part 

of revegetation projects (seeded). 

Invasive nonnative plants can alter 

multiple attributes of ecosystems, 

including geomorphology, wildfire 

regime, hydrology, microclimate, 

nutrient cycling, and productivity 

(Dukes and Mooney 2003, pp. 1-35). 

They can also negatively affect native 

plants through competitive exclusion, 

niche displacement, hybridization, and 

competition for pollinators; examples 

are widespread among native taxa and 

ecosystems (D’Antonio and Vitousek 

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

Mooney and Cleland 2001, p. 1). 

Geospatial analyses indicate that 

approximately 20 percent of the total 

area of all L. papilliferum EOs 

rangewide is dominated by introduced 

invasive annual and perennial plant 

species (Stoner 2009, p. 81), and 

monitoring of HIP transects rangewide 

indicates that nonnative plant cover is 

continuing to increase at a relatively 

rapid pace (Colket 2008, pp. 1, 3). 

Although, historically, disturbance of 

native communities tended to pave the 

way for invasion by nonnative plants, 

today nonnative annual plants such as 

Bromus tectorum are so widespread that 

they have been documented spreading 

into areas not impacted by disturbance 

(Piemeisel 1951, p. 71; Tisdale et al. 

1965, pp. 349-351; Stohlgren et al. 1999, 

p. 45). The known impacts of nonnative 

plants on L. papilliferum are discussed 

in this section. 

One of the characteristics of slickspots 

is that they are largely devoid of native 

shrubs, grasses, and forbs, with the 

exception of Lepidium papilliferum; this 

is one of the features that make 

slickspots relatively easy to detect on 

the landscape (Moseley 1994, pp. 8, 14; 

Fisher et al. 1996, pp. 3-4, 11; Colket 

2008, p. 1). Lepidium papilliferum has 

adapted to the unique edaphic and 

hydrological (soil and water) properties 

of the slickspot microsites that it 

inhabits, and has thus evolved with 

little competition from other native 

plants (Moseley 1994, p. 14). Weedy, 

nonnative plants have begun to invade 

these slickspots, however, including 

Agropyron cristatum, Bromus tectorum, 

Lepidium perfoliatum, Ceratocephala 

testiculata, and, in some areas, Bassia 

prostrata (Colket 2009, p. 3; Fisher et al. 

1996, p. 4; Sullivan and Nations 2009, 

p. 99). 

In our January 12, 2007, finding (72 

FR 1622), we recognized invasive 

nonnative plants as one of the primary 

factors degrading the quality of L. 

papilliferum’s habitat, but at the time 

we had no evidence demonstrating any 

negative association between the 

presence of nonnative plant species and 

either the abundance of L. papilliferum 

itself or the proportion of L. 

papilliferum in flower. For example, 

Menke and Kaye (2006b, p. 15) 

originally reported no correlation 

between the abundance of L. 

papilliferum and weedy species cover, 

either within slickspots or in the 

surrounding matrix vegetation. 

However, more recent analyses of the 

additional years of data now available 

have revealed a significant negative 

association between the presence of 

weedy species and the abundance or 

density of L. papilliferum, to the point 

that L. papilliferum may be excluded 

from slickspots (Sullivan and Nations 

2009, pp. 109-112). Although the 

specific mechanisms are not well 

understood, some of these plants, such 

as A. cristatum and B. tectorum, are 

strong competitors in this arid 

environment for such limited resources 

as moisture, which tends to be 

concentrated in slickspots (Pyke and 

Archer 1991, p. 4; Moseley 1994, p. 8; 

Lesica and DeLuca 1998, p. 4), at least 

in the subsurface soils (Fisher et al. 

1996, pp. 13-16). The available 

information, detailed below, indicates 

that nonnative plants in both slickspots 

and the surrounding matrix vegetation 

are negatively affecting L. papilliferum. 

Furthermore, we now have additional 

evidence that areas occupied by L. 

papilliferum formerly dominated by 

native vegetation are experiencing 

relatively rapid increases in cover of 

nonnative plant species; for example, 

Colket (2008, pp. 1, 3) reports that 22 of 

the 80 HIP transects (28 percent) have 

shown increases in nonnative plant 

species cover of 5 percent or more over 

the last 4 to 5 years. Here we discuss the 

effects of nonnative plant species on L. 

papilliferum and its habitat, detailing 

the evidence related to unseeded and 

seeded nonnative plants separately. 

Unseeded Nonnative Invasive Plants 

The most common unseeded 

nonnative annual grasses known to 

occur in Lepidium papilliferum’s habitat 

include Bromus tectorum and 

Taeniatherum caput-medusae. Annual 

nonnative forbs now commonly 

associated with slickspots include 

Lepidium perfoliatum, Salsola kali 

(tumbleweed, also known as Russian 

thistle), Sisymbrium altissimum (tumble 

mustard, also known as tall tumble 

mustard), and Ceratocephala testiculata 

(Colket 2009, pp. 8-9). 

As discussed under Modified Wildfire 

Regime above, Bromus tectorum in 

particular has become dominant in 

many sagebrush-steppe habitat areas 

during the last century due to livestock 

grazing, agriculture, and wildfire 

impacts (Pickford 1932, p. 165; 

Piemeisel 1951, p. 71; Peters and 

Bunting 1994, p. 34; Vail 1994, pp. 3- 

4; Brooks and Pyke 2001, pp. 4-6). Vast 

areas of sagebrush shrublands have been 

converted to B. tectorum in the past 

century (about 31,000 mi2 (80,000 km2) 

in the Great Basin alone) (Menakis et al. 

2003, p. 284). Low-elevation sites, 

which are relatively dry and experience 

wide variation in soil moisture, appear 

to be more vulnerable to B. tectorum 

invasion than higher elevation sites 

with more stable soil moisture. Bromus 

tectorum plants tend to be larger and 

more fecund in a post-wildfire 

environment than on unburned sites, 

potentially leading to subsequent 

increases in density on burned sites 

under favorable climatic conditions 

(Zouhar 2003a, as summarized in 

Zouhar et al. 2008, p. 154). The invasion 

of nonnative plant species, particularly 

annual grasses, has had a greater effect 

on the lower elevation sagebrush 

shrublands in the Snake River Plain of 

Idaho that historically experienced less 

frequent fire than higher elevation sites 

in the region; the higher elevation sites 

have higher precipitation and 

historically had more fine grasses and 

more frequent wildfires (Gruell 1985, 

pp. 103-104; Peters and Bunting 1994, p. 

33). These lower elevation sagebrush 

shrublands include the range of 

Lepidium papilliferum. As detailed 

under Modified Wildfire Regime, above, 

the B. tectorum–fire cycle modifies and 

degrades the native sagebrush-steppe 

ecosystems on which L. papilliferum 

depends, and recurrent fire prevents the 

system from achieving the late seral 

stage condition that characterizes highquality habitat for the species. 

In addition to perpetuating the cycle 

of increased wildfire within the range of 

Lepidium papilliferum, nonnative 

plants such as Bromus tectorum and 

Taeniatherum caput-medusae can have 

additional negative impacts on L. 

papilliferum through competition, 

displacement, and altering the 

ecological function of slickspots. 

Invasive grasses can replace native 

plants such as L. papilliferum by 

outcompeting them for resources, such 

as soil nutrients or moisture (Brooks and 

Pyke 2001, p. 6, and references therein). 

Bromus tectorum in particular appears 

to displace native plants by prolific seed 

production, early germination, and 

superior competitive abilities for the 


srobinson on DSKHWCL6B1PROD with RULES4
52032 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

extraction of water and nutrients 

(Pellant 1996, pp. 3-4; Pyke 2007). In 

addition, B. tectorum is capable of 

modifying the ecosystems by altering 

the soil temperatures and soil water 

distribution (Pellant 1996, p. 4). 

Evidence that B. tectorum is likely 

displacing L. papilliferum is provided 

by Sullivan and Nations’ (2009, p. 135) 

statistical analyses of L. papilliferum 

abundance and nonnative invasive plant 

species cover within slickspots. 

Working with 5 years of HIP data 

collected from 2004 through 2008, 

Sullivan and Nations found that the 

presence of other plants in slickspots, 

particularly invasive exotics such as 

Bassia prostrata and Bromus tectorum, 

was associated with the almost 

complete exclusion of L. papilliferum 

from those microsites (Sullivan and 

Nations 2009, pp. 111-112). Of all the 

factors considered in their analysis, only 

the amount of B. tectorum in the plant 

community around slickspots showed a 

consistent relationship with the 

abundance of L. papilliferum across all 

three physiographic regions comprising 

the range of the species, and in all cases 

this relationship was significantly 

negative (Sullivan and Nations 2009, 

pp. 131, 136-137). 

In addition to the roughly 3.3 million 

ac (1.3 million ha) of public lands in the 

Great Basin already dominated by 

Bromus tectorum (translating to about 

5,156 mi2 or 13,354 km2), Pellant (1996, 

p. 1, and references therein) identifies 

another 76.1 million ac (30.8 million ha, 

or 119,000 mi2 (308,210 km2)) either 

infested with this nonnative grass or 

susceptible to invasion by the species, 

and suggests that the spread of B. 

tectorum could increase in the future 

due to its adaptability, including the 

presence of multiple genotypes. 

The dominance of Bromus tectorum 

in an area may also be positively related 

to the density of Owyhee harvester ants 

(Pogonomyrmex salinus), which 

represent an emerging threat to 

Lepidium papilliferum. The 

replacement of sagebrush by annual 

grasses, such as B. tectorum, apparently 

creates conditions favorable to nesting 

of the native harvester ant, leading to 

expanded range and density of this 

potentially important seed predator of L. 

papilliferum. The invasion of B. 

tectorum and other nonnative annual 

grasses may thus exacerbate the threat 

posed by seed predation (see Factor C, 

Disease or Predation, below, for details). 

Bradley and Mustard (2006, p. 1146) 

found that the best indicator for 

predicting future invasions of Bromus 

tectorum was the proximity to current 

populations of the grass. Colket (2009, 

pp. 37-49) reports that 52 of 80 HIP 

transects (65 percent) had B. tectorum 

cover of 0.5 percent or greater within 

slickspots in at least 1 year between 

2004 and 2008; nearly 95 percent of 

slickspots had some B. tectorum 

present. If current proximity to B. 

tectorum is an indicator of the 

likelihood of future invasion by that 

nonnative species, then Lepidium 

papilliferum is highly vulnerable to 

future invasion by B. tectorum 

throughout its range. If the invasion of 

B. tectorum continues at the rate 

witnessed over the last century, an area 

far in excess of the total range occupied 

by L. papilliferum could be converted to 

nonnative annual grasslands within the 

foreseeable future. First introduced 

around 1889 (Mack 1981, p. 152), B. 

tectorum cover in the Great Basin is 

now estimated at approximately 30,888 

mi2 (80,000 km2) (Menakis et al. 2003, 

p. 284), translating into an historical 

invasion rate of approximately 257 mi2

(666 km2) a year over 120 years. If the 

spread of B. tectorum continues at even 

half of that rate, an area equal in size to 

the 2,250 mi2 (5,800 km2) range of L. 

papilliferum would be invaded by B. 

tectorum in less than 20 years. In 

addition, climate change models for the 

Great Basin region also predict climatic 

conditions that will favor the growth 

and further spread of B. tectorum (see 

Factor E, Climate Change, below). 

There is increasing evidence that 

nonnative plants are invading formerly 

sparsely vegetated slickspots (Moseley 

1994, p. 14), and the presence of these 

nonnative plants within slickspots is 

negatively associated with the 

abundance of Lepidium papilliferum 

(Sullivan and Nations 2009, pp. 109- 

113). Although Menke and Kaye (2006b, 

p. 15) found no significant correlation 

between weedy species cover and either 

abundance of L. papilliferum or 

proportion of L. papilliferum in flower 

based on a single year of observations 

(2004), Sullivan and Nations’ (2009, p. 

135) statistical analyses of plant 

abundance and nonnative invasive plant 

species cover within slickspots (based 

on 5 years of HIP data from 2004 

through 2008) indicated that L. 

papilliferum abundance decreased with 

increased Bromus tectorum cover in the 

Boise Foothills and the Snake River 

Plain at statistically significant levels. 

There was no relationship evident on 

the Owyhee Plateau; however, the 

authors note that there is little B. 

tectorum in the slickspots in that region. 

Therefore, the nature of any relationship 

in that region would be difficult to 

detect (Sullivan and Nations 2009, p. 

135). Although B. tectorum is not yet 

invading slickspots to a great extent in 

the Owyhee Plateau region, its 

increasing presence across the 

landscape is indicative of degraded L. 

papilliferum habitat (Sullivan and 

Nations 2009, pp. 136-137). Similarly, 

survey sites on the Owyhee Plateau 

from 2000 through 2002 with 

‘‘abundant’’ weeds (referred to as 

unseeded nonnative plants) had 26 

percent fewer total L. papilliferum 

plants when compared to the leastweedy sites, and more rosettes than 

flowering plants, indicating 

proportionally fewer flowering L. 

papilliferum plants (Popovich 2009, p. 

26). 

Another nonnative annual grass, 

Taeniatherum caput-medusae, overlaps 

in both distribution and habitat 

requirements with Bromus tectorum. 

Introduced in the late 1880s, the 

subsequent rapid spread of T. caputmedusae, has caused serious 

management concerns in the Great 

Basin because of its vigorous 

competitive nature and ability to 

transform native shrub and perennial 

grass ecosystems to annual grass 

monocultures, much like B. tectorum 

(USDA Forest Service Fire Effects 

Information System 2009).. 

Taeniatherum caput-medusae cover 

increases and rapidly spreads under 

frequent fires at the expense of native 

species, and may even replace B. 

tectorum (Hironaka 1994, pp. 89-90; 

Brooks and Pyke 2001, p. 5; USDA 

Forest Service Fire Effects Information 

System 2009). Taeniatherum caputmedusae is unpalatable to livestock and 

has low forage value. When dry, the 

dead T. caput-medusae vegetation 

decomposes slowly and forms a 

persistent dense litter on the soil 

surface. Similar to B. tectorum, 

accumulated T. caput-medusae litter 

enables stand-replacement fires to occur 

in ecosystems that are not adapted to 

frequent fire (Brooks and Pyke 2001, p. 

5; Norton et al. 2007, pp. 2-3; Hironaka 

1994, pp. 89-90). Wildfires in T. caputmedusae-infested areas usually 

minimally damage soil surfaces and soil 

erosion is limited, but enough T. caputmedusae seeds typically survive to 

produce thin, vigorous stands of T. 

caput-medusae plants the following 

year. Within a few years, stand densities 

approach pre-fire levels, perpetuating 

the modified wildfire regime (Hironaka 

1994, pp. 89-90; Brooks and Pyke 2001, 

p. 5; Norton et al. 2007, pp. 2-3; 

Chambers 2008, p. 53). As with B. 

tectorum, T. caput-medusae continues 

to expand its range in association with 

increased fire frequency (USDA Forest 

Service Fire Effects Information System 

2009). 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52033 

Other nonnative invasive species in 

sagebrush-steppe habitats have the 

ability to displace native plant species, 

such as Lepidium papilliferum. For 

example, Chondrilla juncea (rush 

skeletonweed) is an unseeded, 

nonnative, invasive, perennial plant 

found in some HIP transect slickspots 

(Colket 2009, p. 8). In 2008, C. juncea 

was observed during native plant 

surveys in the Boise Foothills to be 

widespread and occurring in small, lowdensity stands (Cole 2008, p. 13). 

Ongoing recreation-related soil 

disturbance from pedestrians and 

cyclists will likely encourage C. juncea 

invasion into L. papilliferum sites (Cole 

2008, p. 13). Chondrilla juncea moves 

into new areas primarily through windtransported seed dispersal and root 

fragment transport, but persists and 

expands primarily through bud 

formation on root systems of established 

plants (Kinter et al. 2007, p. 393; USFS 

2009). Disturbance to aboveground C. 

juncea plants stimulates formation of 

root buds, making this invasive plant 

difficult to control, and potentially 

allowing this nonnative invasive plant 

to displace L. papilliferum. 

Examining the presence of Bassia 

prostrata, Bromus tectorum, Agropyron 

cristatum, total seeded nonnative 

plants, total unseeded nonnative plants, 

and biological crust cover, Sullivan and 

Nations (2009, p. 109) concluded that 

‘‘near mutual exclusivity of these plants 

(excepting biological crust) and 

slickspot peppergrass is a dominant 

pattern.’’ Although, historically, few 

species other than L. papilliferum were 

found in slickspots, nonnative plant 

species now appear to be displacing L. 

papilliferum from its specialized 

slickspot microsite habitats. The results 

from 2008 HIP monitoring revealed that 

all 80 HIP transects (10 transects on the 

Boise Foothills, 48 transects on the 

Snake River Plain and 22 transects on 

the Owyhee Plateau) monitored within 

54 EOs had some nonnative, unseeded 

plant cover (Colket 2009, Table 4, pp. 

37-49). Within some transects, the 

amount of nonnative plant cover within 

slickspots was high. For example, 

within the Boise Foothills, 1 of 10 HIP 

transects had 85 percent nonnative 

plant cover and 1 of 10 transects had 

nonnative plant cover between 25 and 

50 percent of the transect. On the Snake 

River Plain, 2 of 48 transects had 

nonnative plant cover between 25 and 

50 percent of the transect. Unseeded 

nonnative invasive plant cover was 

lowest in the Owyhee Plateau, where 

none of the 22 HIP transects had 

unseeded nonnative invasive plant 

cover greater than 10 percent (Colket 

2009, Table 4, pp. 37-49). At this point, 

a minority of transects has a high degree 

of nonnative plant cover. The evidence 

indicates, however, that the degree of 

nonnative plant cover is increasing, and 

can do so at a relatively rapid rate 

(because Colket (2008, pp. 1-3) reported 

increases in nonnative plant species 

cover of 5 percent or more over the span 

of 4 to 5 years in 28 percent of the HIP 

transects formerly dominated by native 

plant species). 

Existing conservation measures 

designed to reduce the potential adverse 

effects of nonnative, unseeded species 

are addressed in three conservation 

documents (CCA, U.S. Air Force 

Integrated Natural Resource 

Management Plan (INRMP), and 

IDARNG INRMP) that apply to 

approximately 98 percent of Lepidium 

papilliferum’s occupied range. The CCA 

includes conservation measures 

designed to protect remnant blocks of 

native vegetation, prioritize weed 

control measures at L. papilliferum EOs, 

develop and implement protective weed 

control techniques, describe 

revegetation requirements for disturbed 

areas, educate the public on nonnative 

species and their spread, use vehicle 

wash points and stations, and support 

research and funding for nonnative 

species control (State of Idaho et al. 

2006, pp. 131-132). The military also 

has a number of ongoing efforts to 

suppress nonnative species on U.S. Air 

Force and IDARNG managed lands. All 

military vehicles entering the IDARNG’s 

OTA from areas more than 50 mi (80.4 

km) away are washed at a high-pressure 

wash-rack facility to prevent weed seed 

introduction. Small patches of noxious 

weeds are hand-pulled when they are 

found by IDARNG staff, and other larger 

noxious weed sites on the OTA are 

reported annually to BLM for treatment 

(IDARNG 2004, p. 67). The U.S. Air 

Force tries to reduce the impacts of 

exotic annual species by reseeding 

disturbed areas with native vegetation to 

the maximum extent practicable, 

eradicating noxious weeds prior to their 

spreading, and requiring the cleaning of 

U.S. Air Force vehicles and equipment 

on a wash rack upon return to the base. 

The U.S. Air Force avoids the use of 

pesticides within 25 ft (8 m) of 

slickspots and uses pesticides only if 

wind conditions are favorable (directed 

away from the slickspot) to prevent the 

loss of L. papilliferum (U.S. Air Force 

2004, pp. R-4, R-5). While these efforts 

are beneficial, their effectiveness is 

limited by the challenge of controlling 

or eliminating invasive nonnative plants 

from all the sagebrush-steppe 

ecosystems where L. papilliferum 

occurs, due to the sheer magnitude of 

the problem, logistical and budgetary 

limitations, and the still-evolving 

methodology for restoring these 

ecosystems to their natural condition 

(Bunting et al. 2003, p. 82; Pyke 2007). 

Seeded Nonnative Invasive Plants 

Rangeland revegetation projects on 

public lands in southwest Idaho have 

included providing forage for livestock, 

controlling erosion, preventing 

wildfires, reducing nonnative annual 

grass density, and rehabilitating 

watersheds. To meet these revegetation 

objectives, land managers often plant 

nonnative species, which can 

outcompete native species and result in 

decreased biodiversity (summarized by 

Harrison et al. 1996; Beyers 2004, p. 

953). For example, Agropyron cristatum, 

a forage species that was once 

commonly planted in revegetation 

projects within the range of Lepidium 

papilliferum, is a strong competitor, and 

its seedlings are better than some native 

species at acquiring moisture at low 

temperatures (Pyke and Archer 1991, p. 

4; Lesica and DeLuca 1998, p. 1; 

Bunting et al. 2003, p. 82). We now 

know that when A. cristatum is present 

in a slickspot, L. papilliferum tends to 

be few in numbers or absent altogether 

(Sullivan and Nations 2009, p. 109), 

indicating that A. cristatum is likely 

displacing L. papilliferum. Thinopyrum 

intermedium (intermediate wheatgrass, 

formerly Agropyron intermedium) has 

also been seeded in some southern 

Idaho rangeland areas, including the 

Owyhee Plateau region, where it is 

found in L. papilliferum sites on U.S. 

Air Force (CH2MHill 2008a, p. 5) and 

BLM lands (ERO Resources Corporation 

2008, p. 10; Colket 2009, pp. 37-49). 

One long-term research study (73 years) 

conducted in Utah, Idaho, and Nevada 

found that once established, T. 

intermedium and Bromus inermis 

(smooth brome) dominate a site and 

suppress not only other herbaceous 

species, but also Artemisia spp. and 

Purshia tridentata (bitterbrush) 

recruitment (Monson 2002, p. 2). 

Natural recruitment of native species on 

the U.S. Air Force’s Juniper Butte Range 

in the Owyhee Plateau region is 

impeded by establishment of T. 

intermedium (CH2MHill 2008a, p. 17). 

The introduction of these nonnative 

plants and consequent displacement of 

the native species that comprise late 

seral stage sagebrush habitat contributes 

to the ongoing degradation and loss of 

quality habitat for Lepidium 

papilliferum. 

In addition to contributing to the 

degraded condition of Lepidium 

papilliferum habitat in general, the best 


srobinson on DSKHWCL6B1PROD with RULES4
52034 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

available data suggest that there may be 

a negative relationship between seeded 

nonnative plant species and the 

abundance of L. papilliferum. Statistical 

analyses of habitat type and L. 

papilliferum abundance from surveys 

conducted from 2000 through 2002 in 

the Owyhee Plateau region indicated 

that the number of L. papilliferum 

plants per site was three times higher in 

native sagebrush-steppe habitat areas or 

burned areas that had not been seeded 

compared to areas seeded with 

Agropyron cristatum (Popovich 2009, p. 

25). Similarly, the density of L. 

papilliferum plants was nearly twice as 

high in a site dominated by native 

grasses than in a site that had been 

seeded with A. cristatum on the 

Owyhee Plateau (Young 2007, p. 28). 

Rangewide, there was no statistical 

relationship between A. cristatum cover 

and L. papilliferum abundance based on 

2004 through 2008 HIP data (Sullivan 

and Nations 2009, p. 136). Although the 

data regarding A. cristatum in the 

surrounding plant community thus 

appear to be somewhat equivocal, the 

evidence suggests that A. cristatum 

successfully competes with and 

ultimately displaces L. papilliferum 

once it invades occupied slickspots 

(Sullivan and Nations 2009, p. 109). 

Bassia prostrata is another nonnative 

species that has been used for rangeland 

habitat restoration. Abundant numbers 

of B. prostrata plants have been 

observed (greater than 1,000 plants) in 

relatively small slickspots, and B. 

prostrata is documented as a direct 

competitor with Lepidium papilliferum 

in slickspots (DeBolt 2002; Quinney 

2005). An evaluation study of the Poen 

Fire rehabilitation project located in the 

Snake River Plain region documented 

the loss of L. papilliferum along five 

monitoring transects, coupled with a 

dramatic increase in B. prostrata over a 

6–year period following aerial seeding 

after the fire (DeBolt 2002). 

Observations of four slickspots 

supporting both L. papilliferum plants 

and B. prostrata plants in 2000 were 

void of L. papilliferum and dominated 

by B. prostrata in 2005 (Quinney 2005). 

Sullivan and Nations (2009, pp. 110- 

112) also found that L. papilliferum was 

absent from slickspots when B. 

prostrata was present; this relationship 

was particularly strong on the Snake 

River Plain, which comprises more than 

80 percent of the EO area for L. 

papilliferum. These observations all 

indicate that B. prostrata is a strong 

competitor with L. papilliferum in 

slickspots and is capable of excluding L. 

papilliferum from slickspots within a 

short period of time. 

Although Bassia prostrata has not 

been observed at the HIP transects on 

the OTA (ICDC 2007b, p. 1), it has been 

documented on five HIP monitoring 

transects in the Snake River Plain region 

at least once between 2004 and 2008. 

While the majority of these transects 

have less than 1 percent cover of B. 

prostrata, one transect (19B) is 

documented as having up to 38.5 

percent cover of B. prostrata within 

slickspots (Colket 2009, Table 4, p. 39). 

In 2006, five new observations of B. 

prostrata occurring within slickspots 

were documented at four HIP transects 

in the Snake River Plain region and one 

HIP transect in the Boise Foothills 

region, in addition to the three HIP 

transects located on the Snake River 

Plain region, where it was previously 

observed. Four of these five B. prostrata 

observations were in permanently 

marked slickspots on HIP transects. As 

B. prostrata had not been detected in the 

general occurrence area or along the 

vegetation transect before it appeared in 

the slickspots, this indicates that B. 

prostrata can invade formerly 

unoccupied slickspots quickly. 

Expansion of seeded B. prostrata into 

unseeded areas could be detrimental to 

Lepidium papilliferum and its habitat, 

due to its rapid growth within slickspots 

and ability to replace L. papilliferum 

within slickspots (ICDC 2007a, p. 29; 

see also discussion above). In addition, 

between 2004 and 2008, B. prostrata 

was documented in the general area 

around six HIP transects (but not within 

the slickspots themselves, as above); 

five of these six observations were first 

detected in 2008 (Colket 2009, Table 4, 

pp. 38-46), indicating that this invasive 

species is quickly moving into areas 

where it has not been observed before 

and that currently support L. 

papilliferum. Bassia prostrata is also 

documented to occur in slickspots in 

areas that had not been seeded with this 

invasive forb species after the Poen Fire 

(DeBolt 2002), indicating the species is 

spreading on its own. 

The 2008 HIP monitoring results 

revealed that, of the 80 HIP transects 

monitored within 54 EOs, 18 transects 

had some level of nonnative, seeded 

plant cover (Colket 2009, Table 4, pp. 

37-49). For example, seeded nonnative 

invasive plant cover was highest on the 

Owyhee Plateau region, where 4 of 22 

transects had nonnative, seeded species 

cover between 5 and 10 percent and 11 

of 22 transects had nonnative, seeded 

plant cover below 1 percent (Colket 

2009, Table 4, pp. 46-49). Nonnative, 

seeded plant cover is minimal in the 

remainder of the range of Lepidium 

papilliferum, with the Boise Foothills 

region only having 3 of 10 HIP transects 

with nonnative, seeded plant cover in 

2008, and the Snake River Plain region 

having only 4 of 48 transects with 

nonnative, seeded plant cover in 2008. 

In general, the documented percentage 

of nonnative plant cover in the 2008 HIP 

transect monitoring is attributable to 

Agropyron cristatum, except for one site 

in the Snake River Plain region that 

contains 14.1 percent cover in Bassia 

prostrata, down from 38.5 percent cover 

in 2007 (Colket 2009, p. 39). 

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 past wildfire 

rehabilitation efforts (U.S. Air Force 

1998, pp. 3-120 to 3-121). 

Increases in cover of invasive, 

nonnative, seeded grass species may 

also be problematic for Lepidium 

papilliferum. After HIP transect 715 was 

fenced in 2005, Agropyron cristatum 

cover increased so much that the 

slickspots were barely visible in 2008 

(Colket 2009, p. 23). The number of L. 

papilliferum individuals at HIP transect 

715 ranged from 224 to 273 in 2004 and 

was 286 in 2005, but these numbers 

dropped to 16, 17, and 10 plants in 

2006, 2007, and 2008, respectively. It is 

unclear whether this decrease in the 

number of L. papilliferum plants is 

related to the increase in A. cristatum 

cover and associated litter cover in the 

slickspots (Colket 2009, p. 23). 

Although nonnative seed was 

formerly used extensively for 

revegetation projects, currently the 

trend is toward increased use of native 

seed. Management practices involving 

the use of nonnative seed vary among 

the land management agencies. As 

specified in a Conservation Agreement 

between the BLM and the Service (U.S. 

BLM and FWS 2006, p. 17), Bassia 

prostrata is not recommended for 

rehabilitation projects within the range 

of Lepidium papilliferum, although it 

may be used as a last resort species for 

stabilization projects adjacent to L. 

papilliferum habitat. BLM emphasizes 

the use of native plants, including forbs, 

in seed mixes and avoids the use of 

invasive nonnative species when 

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

26). In January 2004, the BLM issued an 

Instruction Memorandum directing 

employees to comply with CCA 

requirements for emergency 

stabilization and wildfire rehabilitation 

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

71). Use of native species in extensive 

wildfire rehabilitation projects varies 

based on native seed availability and 

site conditions that may affect seeding 

success rates. For example, the 2007 

Murphy Complex Fire burned a portion 

of areas occupied by L. papilliferum in 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52035 

the Owyhee Plateau region. Seed 

mixtures for emergency stabilization 

and restoration efforts used both native 

and non-invasive nonnative species; 

however, BLM did not use any 

Agropyron cristatum, B. prostrata, or 

Thinopyrum intermedium seed in the 

Murphy Complex Fire restoration effort 

(U.S. BLM 2008a, p. 1). In contrast, 120 

ac (48.6 ha) that burned in the 2005 

North Ham Fire, located within 

Management Area 10 in the Snake River 

Plain region, was drill-seeded with a 

nonnative, perennial grass-seed mixture 

comprised of 50 percent A. cristatum 

and 50 percent Psathyrostachys juncea 

(Russian wildrye) (U.S. BLM 2008a, p. 

16). Drill and aerial seedings 

implemented in 2006 and 2007 in 

response to the Cold Fire (also in 

Management Area 10) included both 

native and nonnative seed mixtures. In 

some cases, BLM determined postwildfire seedings using nonnative 

species were preferable due to their 

ability to compete successfully with the 

high density of Bromus tectorum 

present in some L. papilliferum MAs 

(U.S. BLM 2008a, p. 24). 

Although the use of native plant 

species for post-wildfire rehabilitation 

projects is preferable, there have been 

ongoing problems with the availability 

and high cost of native seed (Jirik 1999, 

p. 110; Brooks and Pyke 2001, p. 9; 

Zouhar et al. 2008, p. 265). In recent 

years, BLM has been investing more 

resources in securing native seed and 

stock reserves through the Great Basin 

Native Plant Selection and Increase 

Project and the Great Basin Restoration 

Initiative. Consequently, more native 

seed and plant sources are available for 

ongoing and future restoration efforts for 

sagebrush-steppe habitat, but more 

progress is needed to ensure the 

availability and affordability of native 

seed for restoration efforts. 

The U.S. Air Force and the IDARNG 

have ongoing efforts to address invasive, 

nonnative, seeded plants on their 

managed lands. The U.S. Air Force uses 

both native and nonnative, non-invasive 

plant materials and does not use Bassia 

prostrata, Thinopyrum intermedium, or 

salt-tolerant species such as Atriplex 

canescens (four-wing saltbush) in their 

restoration and revegetation efforts, with 

native plants used to the maximum 

extent practicable and in concert with 

the military mission for rehabilitation 

efforts on its lands on the Owyhee 

Plateau (U.S. Air Force 2004, p. R-4). 

The IDARNG INRMP for the OTA on the 

Snake River Plain includes objectives 

for maintaining and improving 

Lepidium papilliferum habitat and 

restoring areas damaged by wildfire. 

The plan specifies that the IDARNG will 

use native species and broadcast 

seeding, collecting, and planting small 

amounts of native seed not 

commercially available and will 

monitor the success of seeding efforts 

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

the IDARNG, using historical records, 

has restored several areas using native 

seed and vegetation that was present 

prior to past wildfires. The IDARNG 

continues to use restoration methods 

that avoid or minimize impacts to L. 

papilliferum or its habitat, with an 

emphasis on maintaining species 

present in presettlement times (IDARNG 

2004, p. 73). 

Summary of Invasive Nonnative Plant 

Species 

Invasive nonnative plant species pose 

a serious and significant threat to 

Lepidium papilliferum, especially when 

the synergistic effects of nonnative, 

annual grasses and wildfire are 

considered. Invasive, nonnative, 

unseeded species that pose threats to L. 

papilliferum include the annual grasses 

Bromus tectorum and Taeniatherum 

caput-medusae that are rapidly forming 

monocultures across the southwestern 

Idaho landscape. Nonnative plant 

species contribute to increased fire 

frequency, alter ecological function, 

outcompete and displace native plant 

species, and degrade the quality and 

composition of sagebrush-steppe habitat 

for L. papilliferum. The presence of B. 

tectorum in the surrounding plant 

community shows a consistently 

significant negative relationship with 

the abundance of L. papilliferum across 

all physiographic regions (Sullivan and 

Nations 2009, pp. 131, 137), and a 

significant negative relationship with L. 

papilliferum abundance within 

slickspots in the Snake River Plain and 

Boise Foothills regions (Sullivan and 

Nations 2009, p. 112). These results 

contrast with the information that was 

available to us at the time of our 2007 

finding, which did not indicate any 

statistically significant relationship 

between invasive nonnative plants and 

the abundance of L. papilliferum, either 

in slickspots or in the surrounding plant 

community (72 FR 1622, p. 1635; 

January 12, 2007). Additionally, we 

have increasing evidence that nonnative 

plants are invading the slickspot 

microsite habitats of L. papilliferum 

(Colket 2009, Table 4, pp. 37-49) and 

successfully outcompeting and 

displacing the species (Grime 1977, p. 

1185; DeBolt 2002, in litt; Quinney 

2005, in litt; Sullivan and Nations 2009, 

p. 109). Monitoring of HIP transects 

shows that L. papilliferum-occupied 

sites that were formerly dominated by 

native vegetation are showing relatively 

rapid increases in the cover of 

nonnative plant species (Colket 2008, p. 

1, 33). Regarding B. tectorum in 

particular, vast areas of the Great Basin 

are already dominated by this nonnative 

annual grass, and projections are that far 

greater areas are susceptible to future 

invasion by this species (Pellant 1996, 

p. 1). In addition, most climate change 

models project conditions conducive to 

the further spread of nonnative grasses 

such as B. tectorum in the Great Basin 

desert area occupied by L. papilliferum 

in the decades to come (see Climate 

Change under Factor E, below). 

Given the observed negative 

association between the abundance of 

Lepidium papilliferum and invasive 

nonnative plants both within slickspot 

microsites and in the surrounding plant 

community, the demonstrated ability of 

some nonnative plants to displace L. 

papilliferum from slickspots, and the 

recognized contribution of nonnative 

plants such as Bromus tectorum to the 

increased fire frequency that 

additionally poses a primary threat to 

the species, we consider invasive 

nonnative plants to pose a significant 

threat to L. papilliferum. Nonnative 

grasses such as B. tectorum may 

additionally play a role in increased 

seed predation that poses a threat to L. 

papilliferum by providing habitat for the 

expansion of native harvester ant 

colonies (see Factor C, Disease or 

Predation, below). Currently, there are 

no feasible means of controlling the 

spread of B. tectorum or the subsequent 

increases in wildfire frequency and 

extent once B. tectorum is established 

on a large scale (Pellant 1996, pp. 13-14; 

Menakis et al. 2003, p. 287; Pyke 2007). 

The eradication of other invasive 

nonnative plants poses similar 

management challenges, and future land 

management decisions will determine 

the degree to which seeded nonnative 

plants may affect L. papilliferum. Based 

on the lack of effective control 

mechanisms, the demonstrated 

increases in nonnative plant cover in 

the range of the species, and the likely 

increases in cover of B. tectorum and 

other nonnative plant species predicted 

based on their successful invasive 

characteristics and models of climate 

change, we expect the degree of the 

threat from invasive nonnative plant 

species to continue and likely increase 

within the foreseeable future. We 

consider invasive nonnative plants, in 

conjunction with the modified wildfire 

regime, to pose the greatest threat to the 

viability of L. papilliferum. The 

significant threat posed by invasive 

nonnative plants is pervasive 

throughout the range of L. papilliferum. 


srobinson on DSKHWCL6B1PROD with RULES4
52036 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

Development 

Development, as defined for HIP 

monitoring purposes, includes 

buildings, roads, water tanks, utility 

lines, railroad tracks, and fences (Colket 

2009, Appendix A, HIP Protocol, p. 12). 

Agricultural development is recorded 

under a separate category. Residential, 

commercial, and agricultural 

development prior to 1955 has been 

reported as the cause for five 

documented and four probable 

extirpations of Lepidium papilliferum 

(Colket et al. 2006, p. 4). All forms of 

development can affect L. papilliferum 

and slickspot habitat, whether directly 

or indirectly, through habitat conversion 

(resulting in direct loss of individuals 

and permanent loss of habitat), or 

through habitat degradation and 

fragmentation as a result of consequent 

increased nonnative plant invasions, 

increased ORV use, increased wildfire, 

and changes to insect populations (ILPG 

1999, pp. 1-3; Robertson and White 

2007, pp. 7, 13). 

The most direct impact of 

development is the outright loss of 

Lepidium papilliferum populations due 

to habitat conversion, such as when 

habitat occupied by L. papilliferum is 

converted to a residential development 

or an agricultural field, resulting in the 

permanent loss of the plant population 

and the habitat. As mentioned above, 

development has been documented as 

the cause of several population 

extirpations of L. papilliferum in the 

past, and at present, there are 10 

approved or proposed development 

projects located in the Boise Foothills 

and Snake River Plain regions, all 

within the LEPA Consideration Zone 

(an area that contains Lepidium 

papilliferum identified within the CCA) 

(State of Idaho 2008). These activities 

include four approved, planned 

residential communities in Ada County 

totaling 4,062 ac (1,644 ha), and six 

other development projects submitted 

for approval to Ada County totaling 

9,831 ac (3,978 ha). This area is in the 

Boise Foothills, which, although it 

represents a relatively small geographic 

extent of L. papilliferum’s range, 

supports the most dense and regionally 

abundant populations of the species 

(Sullivan and Nations 2009, p. 103). 

Several other planned communities on 

an additional 44,500 ac (18,008 ha) are 

proposed, but have not yet been 

submitted for County or other planning 

agency approval. In addition, large-scale 

planned communities have been 

proposed for the southern portion of the 

Snake River Plain region in Elmore 

County. These numbers reflect only 

planned communities which, by 

definition, are 640 ac (259 ha) or larger 

and do not include smaller 

developments, such as subdivisions 

(State of Idaho 2008). Developments of 

this nature likely lead to the extirpation 

of populations through permanent 

habitat conversion; they may also 

indirectly impact L. papilliferum, as 

described below. While it is unlikely 

that all of these planned communities 

will move forward in the near future 

due to the current economic climate, the 

scale of potential future residential and 

commercial development may impact 

several of the remaining L. papilliferum 

populations across the range of the 

species (State of Idaho 2008). 

Indirect effects to Lepidium 

papilliferum are a likely consequence of 

the linear infrastructure associated with 

urban and residential development. In 

2006, utility lines and accompanying 

roads were documented running 

through at least four EOs, natural gas 

pipelines were documented running 

through two EOs, and existing roads 

bisect at least six EOs (Colket et al. 

2006, Appendix C). Additional 

infrastructure associated with the 

planned development projects described 

above is expected. 

In addition to direct habitat 

destruction and associated loss of 

individual L. papilliferum plants, utility 

corridors and roads may allow increased 

ORV access, resulting in potential 

destruction or degradation of slickspots 

and possible direct mortality of 

individuals of L. papilliferum. They 

may also increase the chance of 

nonnative plant invasions (most notably 

Bromus tectorum, as described above), 

human-ignited wildfires, and contribute 

to habitat fragmentation and its 

associated consequences. The effects of 

these threats are summarized here, and 

additional details are provided under 

Invasive Nonnative Plant Species and 

Current Wildfire Regime, above, and 

Factor E, Habitat Fragmentation, below. 

Transportation and utility corridors 

associated with urban and residential 

development can increase the spread of 

nonnative invasive plants. Roads appear 

to create avenues for invasion by 

Bromus tectorum, for example, because 

there is generally a positive significant 

association between nonnative, 

disturbance-tolerant species such as B. 

tectorum and proximity to roads 

(Forman and Alexander 1998, p. 210; 

Gelbard and Belnap 2003, pp. 424-425, 

430-431; Bradley and Mustard 2006, p. 

1142). Bradley and Mustard (2006, p. 

1146) found an even stronger 

association between the presence of B. 

tectorum and power-line corridors, and 

they suggest that the stronger 

relationship between B. tectorum and 

recent disturbance (that is, power lines; 

roads were considered an historical 

disturbance) suggests that future 

placement of either roads or power lines 

would very likely result in invasion by 

B. tectorum. 

Increased urban and residential 

development also increases the 

probability of human-ignited wildfires, 

presumably by increasing the area of the 

urban-wildland interface (e.g., Keeley et 

al. 1999, p. 1829; Romero-Calcerrada et 

al. 2008, pp. 341, 351; Syphard et al. 

2008, pp. 610-611). Increases in human 

habitation and activity in the rangelands 

of southern Idaho have contributed to 

the increase in wildfire starts in recent 

years. For example, in the Jarbidge Field 

Office area of the BLM (Owyhee Plateau 

region), where 21 of 80 total EOs are 

found, 43 percent of the wildfires 

occurring since 1987 were humancaused (Launchbaugh et al. 2008, p. 3). 

Proximity to urban areas and roads can 

be an important causal factor associated 

with wildfire ignitions (Kalabokidis et 

al. 2002, p. 6; Brooks et al. 2004b, p. 3; 

Romero-Calcerrada et al. 2008, p. 351; 

Syphard et al. 2008, pp. 610-611). 

Many of the ongoing and planned 

developments will require the 

construction of power, gas, and other 

transmission lines, as well as new road 

construction, which will impact and 

fragment Lepidium papilliferum 

habitats. In addition, several interstateutility activities within the range of L. 

papilliferum have been proposed, 

including a new electric transmission 

line between Boardman, Oregon, and 

Murphy, Idaho (Boardman Hemingway 

project); a new transmission line 

between Casper, Wyoming, and 

Murphy, Idaho (Gateway West project); 

and a natural gas pipeline proposed, but 

currently on hold, that would run from 

Opal, Wyoming, through southern Idaho 

and end in Stanfield, Oregon (Sunstone 

Pipeline project) (State of Idaho 2008). 

The proposed route of the Gateway West 

Transmission Line project currently 

bisects habitat occupied by L. 

papilliferum. 

Insect populations may also be 

affected by development, potentially 

impacting the primary vector of 

pollination and genetic exchange for 

Lepidium papilliferum. Insect densities 

have been documented as being lower 

in developed areas than in native 

habitats (Gibbs and Stanton 2001, p. 82; 

McIntyre and Hostetler 2001, p. 215; 

Zanette et al. 2005, p. 117; Clark et al. 

2007, p. 333). Changes in native habitat 

caused by ongoing development or 

conversion of lands to agriculture may 

impact insect pollinator populations by 

removing specific food sources or 

habitats required for breeding or nesting 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52037 

(Kearns and Inouye 1997, p. 298; 

McIntyre and Hostetler 2001, p. 215; 

Zanette et al. 2005, pp. 117-118). 

Habitat isolation and fragmentation 

resulting from development may also 

impact L. papilliferum by decreasing 

pollination from distant sources, 

possibly resulting in decreased 

reproductive potential (e.g., lower seed 

set) and reduced genetic diversity (see 

Habitat Fragmentation and Isolation of 

Small Populations, under Factor E, 

below). Reductions in pollinators due to 

development could thus potentially 

impact L. papilliferum reproductive 

success as well as contribute to reduced 

genetic variability, as the plant is 

dependent on insect pollination for 

successful reproduction and the transfer 

of genetic material between populations. 

Ongoing and planned residential and 

urban development currently threaten 

the long-term viability of Lepidium 

papilliferum occurrences on private 

land, primarily in the Snake River Plain 

and Boise Foothills regions (Moseley 

1994, p. 20; State of Idaho 2008; Stoner 

2009, pp. 13-14, 19-20). All or portions 

of 12 L. papilliferum EOs covering 224 

ac (90.7 ha) (1.0 percent of the total area 

of all EOs - not including EOs managed 

by cities or counties) occur on private 

land subject to development. Two of 

these 12 EOs are smaller than 1 ac (0.4 

ha) and are classified as having fair to 

poor habitat quality (INHP data as of 

January 14, 2009); therefore, these EOs 

are particularly vulnerable to 

extirpation through development. 

Surveys conducted in 2008 documented 

that 21 of 80 HIP transects rangewide 

are located within 213 ft (65 m) of 

development, and 66 of 80 HIP transects 

were within 1,640 ft (500 m) of 

development. Proximity to development 

carries increased risk of mechanical 

disturbances (such as from ORV use), 

increased risk of wildfire ignition and 

invasion by nonnative plant species, as 

discussed above, and possibly decreases 

in the diversity or abundance of 

pollinators as well as vulnerabilities 

associated with fragmentation and 

isolation of small populations, as 

discussed under Factor E, below. 

Summary of Development 

Although the threat of development is 

relatively limited in scope, the impact of 

development on Lepidium papilliferum 

can be severe, potentially resulting in 

the direct loss of individuals, and 

perhaps more importantly, the 

permanent loss of its slickspot microsite 

habitats. The destruction of slickspots is 

of concern due to the finite nature of 

this limited resource. As described in 

the Background section, L. papilliferum 

occurs primarily in these specialized 

slickspot microsites. Slickspots and 

their unique edaphic and hydrological 

characteristics are products of the 

Pleistocene, and they likely cannot be 

recreated on the landscape once lost. 

The potential loss of slickspots, 

particularly those slickspots that are 

occupied by the species and thus clearly 

have the ability to provide the requisite 

conditions to support L. papilliferum, is 

therefore of great concern in terms of 

providing for the long-term viability of 

the species. In addition, since not all 

slickspots have above-ground plants in 

all years (see Background section, 

above), even the loss of currently 

unoccupied slickspots may represent 

the permanent loss of a finite 

specialized microhabitat that has the 

potential to support the species. 

Development additionally has the 

potential for more indirect impacts to 

the species, by contributing to increased 

habitat fragmentation, nonnative plant 

invasion, human-caused ignition of 

wildfires, and potential reductions in 

the population of insect pollinators. 

Based on the best available 

information, past development has 

eliminated some historical Lepidium 

papilliferum EOs, and planned and 

proposed future developments threaten 

several occupied sites in the Snake 

River Plain and Boise Foothills regions. 

Most of the recent development has 

primarily occurred on the Snake River 

Plain and Boise Foothills regions, which 

collectively comprise approximately 83 

percent of the extent of EOs; 

development has not been identified as 

an issue on the Owyhee Plateau (Stoner 

2009, pp. 13-14, 19-20). We are aware of 

10 approved or proposed development 

projects planned for these regions (State 

of Idaho 2008, pp. 3-5), which would 

affect 13 out of 80 EOs (16 percent of 

EOs). Though these developments are 

not certain to occur, they represent the 

likely location and magnitude of 

development over the foreseeable 

future. Development of sagebrushsteppe habitat is of particular concern in 

the Boise Foothills region, which, 

although relatively limited in its 

geographic extent, supports the highest 

abundance of L. papilliferum plants per 

HIP transect (Sullivan and Nations 

2009, pp. 3, 103, 134). 

We consider development to be a 

significant threat within the Boise 

Foothills and Snake River Plain portions 

of the range of Lepidium papilliferum, 

as the outcome of this threat is severe 

where it occurs and likely results in the 

permanent loss of populations and 

irreplaceable slickspot microsite 

habitats. However, this threat is not so 

imminent or sweeping in scope as to 

pose an immediate risk of extirpation to 

the populations of L. papilliferum in 

these regions, nor do we consider the 

threat of development to be equal to the 

magnitude and intensity of the primary 

threats of the modified wildfire regime 

and invasive nonnative plants. We 

consider development to pose a 

significant but lesser threat to the 

species. 

Livestock Use 

Livestock use in areas that contain 

Lepidium papilliferum has the potential 

to result in both positive and negative 

effects on the species, depending on 

factors such as stocking rate and season 

of use. Herbivory by livestock does not 

appear to be a problem, as L. 

papilliferum seems to be largely 

unpalatable to anything but insects (see 

Factor C, Disease or Predation, below). 

Livestock herbivory of invasive 

nonnative plants, especially annual 

grasses such as Bromus tectorum, is 

suggested as one of the potential 

benefits of livestock use that may 

contribute to the restoration of the 

sagebrush-steppe ecosystem (e.g., 

Pellant 1996, pp. 6, 10, 13). At the same 

time, livestock use may have negative 

effects on L. papilliferum. Trampling 

from livestock may result in direct 

damage or mortality of individual L. 

papilliferum plants, and the mechanical 

disturbance damages the slickspot soil 

layers, altering slickspot function and 

creating conditions conducive to the 

invasion of weedy nonnative plants. 

Trampling damage to individual L. 

papilliferum plants appears to be 

relatively isolated, and occasional 

damage or mortality of individual 

above-ground plants is probably not of 

much consequence to the species as a 

whole, because studies and modeling of 

L. papilliferum’s life cycle indicate that 

the persistence of the plant is largely 

dependent on the proliferation of the 

seed bank (Palazzo et al. 2005, pp. 2-4, 

8-9; Meyer et al. 2006, p. 900). If 

trampling results in the mortality of 

individual plants prior to seed set, 

however, that will have a negative 

impact on the persistence of the seed 

bank itself by reducing the number of 

seeds added. 

Livestock trampling can also disrupt 

the soil layers of slickspots, altering 

slickspot function (Seronko 2004; Colket 

2005, p. 34; Meyer et al. 2005, pp. 21- 

22). Trampling when slickspots are dry 

can lead to mechanical damage to the 

slickspot soil crust, potentially resulting 

in the invasion of nonnative plants and 

altering the hydrologic function of 

slickspots. In water-saturated slickspot 

soils, trampling by livestock can break 

through the restrictive clay layer; this is 

referred to as penetrating trampling 


srobinson on DSKHWCL6B1PROD with RULES4
52038 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

(State of Idaho et al. 2006, p. 9). 

Trampling that alters the soil structure 

and the functionality of slickspots 

(Rengasamy et al. 1984, p. 63; Seronko 

2004) likely impacts the suitability of 

these microsites for L. papilliferum. 

Trampling can also negatively affect the 

seed bank by pushing seeds too deeply 

into the soil for subsequent successful 

germination and emergence. Meyer and 

Allen (2005, pp. 6-8) found that seed 

emergence success decreased with 

increasing depth in the soil, from a 

mean of 54 percent at the shallowest 

planting depth of 0.1 in (2 mm) to a 

mean emergence success of 5 percent at 

1.2 in (30 mm) planting depth. 

Two documented incidents suggest 

that trampling has the potential to 

negatively affect L. papilliferum, as 

penetrating livestock-trampling events 

at sites occupied by L. papilliferum 

were followed by large reductions in 

plant abundance in subsequent years, in 

one case going from thousands of plants 

annually to fewer than 10 plants 

recurring each year (Robertson 2003b, p. 

8; Meyer et al. 2005, p. 22). Trampling 

has been suggested as the likely cause 

of the ensuing population reductions in 

these two incidents, but as these were 

observational reports, it is not known 

whether other factors may have also 

acted on these populations. A third 

incident occurred in 2005 at a HIP 

transect monitoring in EO 68, in the 

New Plymouth Management Area of the 

Boise Foothills region. In this incident, 

penetrating livestock trampling was 

observed in 3 of 10 slickspots on the 

transect to a depth of 3 in (8 cm), but 

not to the extent that the livestock 

penetrating-trampling trigger was 

tripped (the trampling ‘‘trigger’’ refers to 

a threshold for trampling set in the CCA, 

and is defined as breaking through the 

restrictive layer under the silt surface 

area of a slickspot during saturated 

conditions; State of Idaho et al. 2006, p. 

9). Since that time, L. papilliferum 

numbers at this transect were 

substantially reduced, going from 

between 631 to 1,277 plants observed in 

2004 to a total of 9 plants in 2005 and 

3 plants in 2006. Similar reductions in 

plant abundance were not observed in 

other HIP transects in the New 

Plymouth MA, indicating that 

environmental factors shared by these 

sites were likely not responsible for the 

observed declines (Colket 2006, pp. 10- 

11). In 2007 and 2008, L. papilliferum 

numbers in this transect appeared to be 

slowly increasing (167 plants in 2007 

and 224 plants in 2008), but had not 

reached the levels observed in 2004 

prior to the incident (Colket 2009, p. 

31). 

Penetrating trampling by livestock 

may have a potentially detrimental 

effect on Lepidium papilliferum; 

however, these effects appear to be 

seasonal (most detrimental when soils 

are wet in the spring) and localized in 

nature. While we acknowledge that 

livestock use may have negative impacts 

on individual slickspots, statistical 

analyses of monitoring data available at 

this time have not demonstrated a 

significant correlation between livestock 

use and the abundance of L. 

papilliferum on a rangewide basis. In a 

statistical analysis of HII data from 1998 

to 2001, recent livestock use did not 

appear to have any effect on Lepidium 

papilliferum, slickspot attributes, and 

plant community attributes (Menke and 

Kaye 2006a, p. iii). The evidence from 

this study is not strong, however, as the 

analysis of grazing impacts were limited 

to areas that had already been burned 

and had likely been previously grazed 

(Menke and Kaye 2006a, pp. 18-19). 

These researchers recommended 

additional analysis to confirm their 

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

Later statistical analyses using 

additional years of rangewide HIP data, 

based on 4 years (2005 to 2008) and 5 

years (2004 to 2008) of livestock use, 

also showed no significant relationships 

between L. papilliferum abundance and 

penetrating livestock trampling in 

slickspots (Salo 2009, p. 1; Sullivan and 

Nations 2009, p. 122), or between L. 

papilliferum abundance and total 

livestock-print cover or livestock-feces 

cover in slickspots (Sullivan and 

Nations 2009, p. 122). Statistical 

analyses of L. papilliferum data from 3 

years of surveys on the Owyhee Plateau 

(2000-2002) showed that sites with low 

levels of livestock trampling exhibited 

greater numbers of L. papilliferum 

plants (averaging twice the total number 

of plants) than sites with high levels of 

trampling, although these results were 

statistically significant for only the year 

2000. A significant positive relationship 

was also found between L. papilliferum 

abundance and distance to water and 

salt stations for use by livestock, with 

total plant abundance increasing with 

increasing distance away from water or 

salt sources (Popovich 2009, pp. 27-28). 

A 2–year study designed to examine 

the relationship between livestock 

trampling effects and Lepidium 

papilliferum density did not show a 

significant change in L. papilliferum 

density as a result of the trampling 

treatment applied. Year-to-year 

variations in L. papilliferum density 

observed in this 2–year study were 

attributed to stochastic environmental 

factors and not trampling events (Young 

2007, p. 19). Further research is needed 

to determine if higher levels of 

trampling, greater mean hoof print 

depths, or more frequent trampling 

treatments may affect L. papilliferum 

abundance (Young 2007, pp. 19-20). The 

ability to discern any livestock 

trampling effects was limited since all 

study areas were grazed 2 to 4 years 

prior to initiation of the study. 

Livestock trampling events 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. 21-22). Saturated 

conditions typically exist for short 

periods each year and may never occur 

in some (drought) years (Hoffman 2005). 

Under the CCA, penetrating trampling is 

monitored to avoid livestock-related 

impacts to slickspots containing L. 

papilliferum. Penetrating trampling is 

defined by the CCA as breaking through 

the restrictive layer (i.e., the middle 

layer of slickspot soil that supports L. 

papilliferum, as described by Meyer and 

Allen 2005, p. 3) under the silt surface 

area of a slickspot during saturated 

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

9). Predicting when soils will be wet in 

a climate with few and inconsistent 

precipitation events is difficult. 

Supplemental salt and watering sites 

can alter livestock distribution, and 

depending on location, can increase or 

decrease trampling of slickspots. As 

described below, protective measures 

provided in several of the existing 

conservation plans for L. papilliferum 

are designed specifically to prevent or 

minimize the impacts to the species 

from livestock trampling, particularly 

during the seasons when slickspot soils 

are wet and most susceptible to damage. 

There are also indirect effects from 

livestock use that have impacted the 

sagebrush-steppe ecosystem. Livestock 

use has been suggested as a contributing 

factor to the spread of both native and 

invasive nonnative plant species (e.g., 

Young et al. 1972, pp. 194-201; Hobbs 

and Huenneke 1992, p. 329; Frost and 

Launchbaugh 2003, pp. 43-45; Loeser et 

al. 2007, p. 95). The spread of Bromus 

tectorum across portions of the Snake 

River Plain has been attributed to 

several causes, including the past 

practice of intensive livestock use in the 

late 1800s (Mack 1981, pp. 145-165). 

A small number of case studies from 

western North America suggest that 

grazing plays an important role in the 

decrease of native perennial grasses and 

an increase in dominance by nonnative 

annual species; however, invasion by 

nonnative grasses has been found to 

occur both with and without grazing in 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52039 

some areas. Today, nonnative annual 

plants such as Bromus tectorum are so 

widespread that they have been 

documented spreading into areas not 

impacted by disturbance (Piemeisel 

1951, p. 71; Tisdale et al. 1965, pp. 349- 

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

therefore, the absence of livestock use 

no longer protects the landscape from 

invasive nonnative weeds (Frost and 

Launchbaugh 2003, p. 44), at least with 

respect to B. tectorum. 

Analysis of 3 years of HII data, from 

1999 through 2001, showed 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 

(indicators of livestock presence) 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 burned in the past 

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

addition, 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). As 

described above, biological soil crusts 

are important to the sagebrush-steppe 

ecosystem and slickspots where 

Lepidium papilliferum occur as they 

stabilize and protect soil surfaces from 

wind and water erosion, retain soil 

moisture, discourage annual weed 

growth, and fix atmospheric nitrogen 

(Eldridge and Greene 1994 as cited in 

Belnap et al. 2001, p. 4). Young (2007, 

p. 19) did not find a significant change 

in the density of Bromus tectorum, 

Ceratocephala testiculata, and 

Lepidium perfoliatum following the 

application of a one-time, annual 

trampling treatment over a 2–year 

period. Both studies (Menke and Kaye 

2006a,b; Young 2007) represent shortterm data sets that likely are not capable 

of reflecting any potential long-term 

effects to L. papilliferum habitat. 

The potential benefit of livestock use 

in reducing wildfire effects through a 

reduction of fine fuels has generated 

discussion in recent years (e.g., Pellant 

1996; Loeser et al. 2007). The 

introduction of cattle, sheep, and horses 

to the Great Basin in the 1860s quickly 

created large ranching operations and 

grazing pressure. Heavy livestock 

grazing removed fine fuels and resulted 

in a substantial reduction in the number 

of fires and the acres burned. Only 44 

fires, burning a total of 11,000 ac (6,875 

ha), were reported from 1880 to 1912 in 

Great Basin rangelands (Miller and 

Narayanan 2008, p. 9). The number of 

livestock in Great Basin and sagebrush 

ecosystems has dropped rapidly since 

the passage of the Taylor Grazing Act of 

1934 (43 USC 315; http://www.blm.gov/ 

wy/st/en/field_offices/Casper/range/ 

taylor.1.html, accessed July 23, 2008, as 

cited in Launchbaugh et al. 2008, p. 2). 

Livestock numbers in Idaho decreased 

in the 1950s primarily from loss of large 

sheep operations. Livestock numbers 

have fluctuated at, or below, this initial 

decrease through the remainder of the 

twentieth century, with a steady 

conversion from sheep to cattle. In the 

last decade, a substantial decrease in 

authorized use of livestock grazing on 

BLM lands in Idaho has been recorded 

(Launchbaugh et al. 2008, p. 2). 

With careful management, livestock 

grazing may potentially be used as a tool 

to control B. tectorum (Frost and 

Launchbaugh 2003, p. 43) or, at a 

minimum, retard the rate of invasion 

(Loeser et al. 2007, p. 95). Although the 

spread of B. tectorum has been strongly 

linked with high-impact grazing, there 

is some evidence to indicate that grazing 

at more moderate levels may potentially 

inhibit the colonization of B. tectorum 

(e.g., Loeser et al. 2007, pp. 94-95); the 

researchers note, however, that 

experimental study over a longer time 

period is needed to verify this tentative 

conclusion. Others, however, have 

suggested that given the variability in 

the timing of B. tectorum germination 

and development, and its ability to 

spread vegetatively, effective control of 

B. tectorum through livestock grazing 

may be a challenge (Hempy-Mayer and 

Pyke, 2008, p. 121). While it is difficult 

to discern the relative importance of 

grazing, climate, and wildfire in 

contributing to nonnative plant 

abundance (D’Antonio et al. 1999, as 

described in Zouhar et al. 2008, pp. 23- 

24), areas with a history of livestock 

grazing often support a wide variety of 

nonnative species, especially in areas 

where nonnatives have been introduced 

to increase the forage value of 

rangelands or pastures (Zouhar et al. 

2008, pp. 23-24). 

Following investigations of the 2007 

Murphy Wildland Fire Complex, firemodeling efforts revealed that grazing in 

grassland vegetation can reduce the 

surface rate of spread and fire-line 

intensity to a greater extent than grazing 

in shrubland vegetation (Launchbaugh 

et al. 2008, pp. 1-2). Under extreme fire 

conditions (low fuel moisture, high 

temperatures, and gusty winds), 

however, grazing applied at moderate 

utilization levels has limited or 

negligible effects on fire behavior. When 

weather and fuel-moisture conditions 

are less extreme, grazing may reduce the 

rate of spread and intensity of fires, 

allowing for patchy burns with low 

levels of fuel consumption 

(Launchbaugh et al. 2008, pp. 1-2). 

Some research also indicates that grazed 

areas have a reduced likelihood of 

wildfire ignitions, likely by reducing the 

availability of fine fuels (RomeroCalcerrada et al. 2008, p. 351). 

Launchbaugh et al. 2008 (p. 32) state 

that ‘‘changes in grazing management 

aimed at managing fuel loads are not 

appropriate for homogeneous 

application across large landscapes and 

multiple management units. Such 

application of grazing across entire 

landscapes at rates necessary to reduce 

fuel loads and affect fire behavior, 

especially under extreme conditions, 

could have negative effects on livestock 

production and habitat goals.’’ Targeted 

grazing to accomplish fuel objectives 

holds promise, but requires detailed 

planning that includes clearly defined 

goals for fuel modification and 

appropriate monitoring to assess 

effectiveness (Launchbaugh et al. 2008, 

p. 32). 

Existing conservation plans (CCA, 

U.S. Air Force INRMP, IDARNG INRMP) 

contain numerous measures to avoid, 

mitigate, and monitor the effects of 

livestock use on Lepidium papilliferum. 

Livestock-grazing conservation 

measures implemented through the 

State of Idaho CCA and the U.S. Air 

Force INRMP apply to all Federal and 

State-managed lands within the 

occupied range of Lepidium 

papilliferum (98 percent of the acreage). 

Conservation measures prescribed by 

the CCA include minimum distances for 

placement of salt and water troughs 

away from occurrences of L. 

papilliferum. Several troughs and salt 

blocks have been moved as a result of 

these measures (State of Idaho et al. 

2005; State of Idaho et al. 2006, p. 133). 

The CCA also includes measures to 

reduce livestock 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. 132-134). High-priority L. 

papilliferum EOs identified in the CCA 

tend to have more restrictive 

conservation measures, such as no early 

spring grazing, fencing to exclude 


srobinson on DSKHWCL6B1PROD with RULES4
52040 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

livestock, and delaying turnout of 

livestock onto allotments when soils are 

saturated (State of Idaho et al. 2006, pp. 

133-134). Delay of turnout is important 

following a soil-saturating precipitation 

event in areas containing L. papilliferum 

since it is difficult to avoid trampling 

effects on saturated slickspot soils. As 

part of the CCA, high-priority EOs were 

designated to emphasize protection and 

restoration of L. papilliferum habitats. 

Criteria for designating these EOs were 

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. To protect these high-priority 

EOs, BLM has shifted the season of 

livestock use on some allotments from 

spring to fall, and implemented a 

deferred-rotation management system 

on some allotments to protect annual 

flowering L. papilliferum plants from 

grazing impacts (State of Idaho et al. 

2006, pp. 133-134). 

Under the Juniper Butte Range 

INRMP, the U.S. Air Force utilizes 

livestock grazing as the primary means 

to minimize wildfire risk by reducing 

the amount of standing grass biomass 

(U.S. Air Force 2004, pp. 6-37 to 6-39). 

Livestock use occurs annually for up to 

60 days while the Juniper Butte Range 

is shut down for clean-up and target 

maintenance. The military training 

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 avoids 

livestock turnout onto the range when 

slickspots are wet in order to reduce 

trampling impacts to slickspot habitats, 

and then uses annual monitoring of 

slickspot soil moisture to determine 

appropriate livestock turnout dates for 

the Juniper Butte Range (U.S. Air Force 

2000, pp. B-18 to B-21). Additionally, in 

2002 the U.S. Air Force established 

three fenced enclosure areas of 173 ac 

(70.0 ha), 8 ac (3.2), and 30 ac (12.1 ha), 

respectively, to preclude all disturbance 

activities and promote Lepidium 

papilliferum research and seed 

collection (Binder in litt. 2006) 

compatible with the Air Force mission. 

Summary of Livestock Use 

Evidence of the direct and indirect 

potential impacts to Lepidium 

papilliferum and slickspots from 

livestock use is relatively limited with 

the data currently available. We 

recognize the potential for negative 

impacts to L. papilliferum populations 

and slickspots that may result from 

seasonal, localized trampling events. 

However, with the implementation of 

conservation measures to minimize 

potential direct and indirect impacts of 

livestock to L. papilliferum, such as 

restricting livestock access to areas 

occupied by L. papilliferum when 

slickspot soils are wet and thus most 

vulnerable to damage, we consider 

livestock use to be a lesser threat to the 

species than the primary threats posed 

by the altered wildfire regime and 

associated increase in nonnative, 

invasive plant species within the range 

of L. papilliferum. We acknowledge that 

current data may not be adequate to 

detect time-dependent issues associated 

with livestock use as only 5 years of HIP 

data are available (Sullivan and Nations 

2009, p. 137), and encourage the 

continued implementation of 

conservation measures and associated 

monitoring to ensure potential impacts 

of livestock trampling to L. papilliferum 

are avoided or minimized. Under 

current management conditions, we do 

not consider livestock use to pose a 

significant threat to L. papilliferum. 

Wildfire Management and Post-Wildfire 

Rehabilitation 

Some activities associated with 

wildfire management, including fuel 

management projects (e.g., greenstrips, 

prescribed fire), wildfire suppression 

activities, and post-wildfire 

rehabilitation, can potentially impact 

existing Lepidium papilliferum 

occurrences and damage slickspot 

habitat by mechanical disturbances or 

by facilitating the establishment of 

nonnative plant species (ILPG 1999). At 

the same time, wildfire management 

and post-wildfire rehabilitation 

activities have the potential to benefit L. 

papilliferum by reducing the occurrence 

and extent of wildfire and by 

revegetating its habitat with native plant 

species to prevent the encroachment of 

invasive nonnative grasses and other 

nonnative plant species, thus reducing 

two of the most significant threats to the 

viability of the species. 

The direct effects of wildfire 

management activities may include 

injury or mortality of individual plants, 

and possibly damage to or destruction of 

the seed bank, through mechanical 

disturbance or direct exposure to 

herbicides. Indirect effects associated 

with mechanical disturbance of 

slickspot soils include an increased 

probability of establishment of invasive 

nonnative plants, burial of the seed 

bank to a depth where seedlings cannot 

emerge from the soil, and mixing of 

slickspot soil layers, which affects 

slickspot function and the suitability of 

a microsite for successful support of the 

species. 

Drill seeding is a rangeland 

rehabilitation technique that is often 

used to restore vegetation after wildfire 

using a rangeland drill that plants and 

covers seed simultaneously in furrows. 

Drill seeding is designed to give the 

seeds moisture and temperature 

advantages to enhance their competitive 

fitness and, consequently, increase their 

survival 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, so no 

attempt was made to avoid them during 

rehabilitation activities. Although more 

recent land management actions have 

established buffers to protect slickspots 

and L. papilliferum from herbicide use, 

we have no data on how the physical 

disturbance from past drill seedings has 

affected L. papilliferum habitats. 

Although drill seeding may have less 

severe impacts on slickspot habitat than 

disking the soil, the success of restoring 

slickspots and L. papilliferum plants 

using drill seeding varies considerably. 

The benefits of post-fire revegetation to 

prevent the establishment of Bromus 

tectorum and subsequent recovery of 

soil surfaces conducive to germination 

and establishment of native perennial 

grass and shrub communities may 

outweigh the impacts from the initial 

short-term disturbance associated with 

drill seeding (Young and Allen 1996, 

pp. 533-534; Bunting et al. 2003, pp. 82- 

85). For further information on the 

effects of nonnative species used for 

rehabilitation and restoration efforts in 

L. papilliferum habitats, see the Seeded 

Nonnative Invasive Plants section 

above. 

Rangewide, disk or drill seeding has 

occurred on portions of 3 of 16 EOs in 

the Boise Foothills region, 10 of 43 EOs 

in the Snake River Plain region, and 9 

of 21 EOs on the Owyhee Plateau region 

(Cole 2009b, Threats Table). The effect 

of drill seeding is also monitored as part 

of the rangewide HIP transects 

monitoring. In 2008, of the 80 Lepidium 

papilliferum transects monitored, 1 

transect in the Boise Foothills region, 1 

transect in the Snake River Plain region, 

and 9 transects in the Owyhee Plateau 

region had evidence of old drill 

seedings within slickspots (Colket 2009, 

pp. 66-67). In a 3–year study on the 

Owyhee Plateau from 2000 through 

2002, Popovich (2009, pp. 8, 11) found 

that unseeded sites supported three 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52041 

times as many L. papilliferum on 

average as sites that had been seeded. 

However, it is unclear whether the 

reduction in L. papilliferum numbers at 

seeded sites is the result of the physical 

disturbance of slickspot soils associated 

with drill seeding, competition from the 

seeded, nonnative invasive grass 

planted at these sites (Agropyron 

cristatum), or a combination of the two. 

In 2006, rangeland emergency 

stabilization and rehabilitation activities 

were implemented on the Snake River 

Plain region in response to seven fires 

(8,312 ac (5,190 ha)) that burned in 

2005, and one fire that burned in 2006 

(161 acres (65 ha)). In 2007, rangeland 

rehabilitation work was implemented 

for 10 additional wildfires that burned 

in 2006. The rehabilitation activities 

included drill seeding utilizing lowimpact, no-till drills, herbicide 

treatment, and aerial seeding (U.S. BLM 

2008a, pp. 4, 8, 13, 16). On the Owyhee 

Plateau, non-ground-disturbing 

techniques were used following the 

Murphy Complex Fire for seeding in 

areas documented to support Lepidium 

papilliferum (U.S. BLM 2008b, Murphy 

map). 

Ground disturbance associated with 

wildfire control, such as the 

establishment of fire lines (areas with 

vegetation removed to break fuel 

continuity), fire camps, firefighting 

staging areas, and the use of wildfiresuppression vehicles, can also impact 

existing Lepidium papilliferum 

occurrences and damage slickspot 

habitat (ILPG 1999). For example, in 

2007, dual-wheel pickup tracks that 

appeared to have been associated with 

wildfire suppression efforts in 2006 

were observed in 5 slickspots (HIP 

transect 032 in Management Area 5) 

during the 2007 HIP transect monitoring 

in the Snake River Plain region (ICDC 

2008, p. 9). 

Firefighting crews and their 

equipment may also indirectly impact 

Lepidium papilliferum through 

dispersal of invasive-plant propagules 

(e.g., seeds or vegetative structures) as 

they travel from other regions to 

wildfires in southern Idaho, or travel 

within the local area of the fire. As fire 

camps are typically set up in large, flat 

clearings that have been disturbed in the 

past, these areas often support 

populations of invasive plants. 

Propagules of these plants adhere to fire 

personnel and their equipment, and 

may be dispersed elsewhere as crews 

move about (Zouhar et al. 2008, p. 273), 

potentially contributing to nonnative 

plant invasions in L. papilliferum 

habitat. 

The construction of fuel breaks 

intended to slow the movement of 

wildfire can benefit Lepidium 

papilliferum by protecting slickspots 

from burning. However, the 

construction of fuel breaks may also 

negatively impact L. papilliferum 

through ground disturbance or the use 

of native seeded species. Nonnative 

species (such as Agropyron cristatum 

and Bassia prostrata) are planted in fuel 

breaks as greenstrips. Greenstrips are 

expected to slow the spread of wildfire 

as the plants remain green (retain higher 

fuel moisture so are less flammable) for 

longer periods than annual plants such 

as Bromus tectorum. Wildfire control 

lines have been documented in three 

EOs, one in the Boise Foothills region 

and two in the Snake River Plain region, 

although none have documented 

wildfire control lines within slickspots 

(Colket et al. 2006, Appendix C; ICDC 

2008, p. 9; Cole 2009b, Threats Table). 

In 2004, the Boise District of BLM 

developed a strategy to assess the 

feasibility of creating fuel breaks to 

protect L. papilliferum. A field 

assessment was conducted of over 

84,550 ac (22,075 ha) of L. papilliferum 

habitat to identify potential fuel break 

routes. Nearly 125 mi (78 km) of 

potential fuel breaks were identified 

that would utilize existing roads and 

trails, in areas that could potentially 

protect up to 10,436 ac (6, 523 ha) 

containing L. papilliferum habitat 

within the LEPA Consideration Zone. 

None of these potential fuel breaks have 

been constructed as of spring 2008. 

There was one fuel break established in 

2006 and 2007 along Interstate 84 from 

milepost 71 (Mayfield Exit) to milepost 

89 (Mountain Home exit) by the Idaho 

Department of Transportation, a 

distance of approximately 30 mi (19 

km). This fuel break likely reduced the 

number of wildfires escaping this 

stretch of Interstate 84, which is a 

source of frequent fire ignitions 

threatening several L. papilliferum 

occupied sites located in the Snake 

River Plain region (U.S. BLM 2008a, p. 

20). 

Through the 2006 CCA, BLM has 

implemented conservation measures 

designed to avoid or minimize impacts 

to the species from wildfire prevention, 

wildfire suppression, and post-wildfire, 

rangeland-rehabilitation activities (State 

of Idaho et al. 2006, Table 5). Rangeland 

rehabilitation and restoration standardoperating procedures for areas occupied 

with Lepidium papilliferum were first 

addressed in an Instruction 

Memorandum in January 2004 (State of 

Idaho et al. 2005, p. 33). Today, the 

BLM and fire cooperators distribute 

maps and inform crew members of the 

location of L. papilliferum to maximize 

wildfire protection in those areas, and to 

minimize potential impacts from firesuppression activities (State of Idaho et 

al. 2006, p. 26). One conservation 

measure of the CCA instructs the BLM 

to use seeding techniques that minimize 

soil disturbance, such as no-till drills 

and rangeland drills equipped with 

depth bands. Implementation of these 

measures for rehabilitation and 

restoration projects have the potential to 

minimize the impact to L. papilliferum 

and its slickspot habitats (State of Idaho 

et al. 2006, p. 26). The BLM also avoids 

spraying herbicides within or near 

known occupied L. papilliferum habitat, 

and conducts pretreatment surveys on 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). More recently, site-specific 

conservation measures to avoid or 

minimize potential impacts to L. 

papilliferum and its slickspot habitat 

were incorporated as part of a 

temporary, livestock-control fencing 

project in response to the Inside Desert 

Fire (in the Owyhee Plateau region) 

emergency stabilization and 

rehabilitation efforts (U.S. BLM 2008b, 

p. 3). 

The U.S. Air Force and IDARNG also 

have implemented a number of ongoing 

efforts to minimize the impacts of 

wildfire-management activities. For 

example, the U.S. Air Force, like the 

BLM, uses drill seeders equipped with 

depth bands to minimize soil 

disturbance and avoids slickspots to the 

maximum extent practicable in drill 

seeding efforts. The U.S. Air Force uses 

broadcast seeding to the maximum 

extent practicable consistent with 

reseeding goals and uses wildfire 

indices to restrict activities when the 

wildfire rating hazard is extreme (U.S. 

Air Force 2004, pp. R-3, R-4). On the 

OTA, the IDARNG restores wildfiredamaged areas by broadcast seeding 

native species. As part of their annual 

training, the IDARNG provides their fire 

crews with maps of all known Lepidium 

papilliferum occupied habitat, and 

actively suppresses all wildfires on the 

OTA. Blading is not permitted in L. 

papilliferum habitat areas on the OTA, 

and existing roadways serve as fuel 

breaks 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 ground-disturbing 

activities can be effective in reducing 

the wildfire threat, as well as in 

reducing rates of spread of nonnative 


srobinson on DSKHWCL6B1PROD with RULES4
52042 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

invasive species associated with 

wildfire management activities 

(IDARNG 2004, p. 73). In 2008, the 

IDARNG also initiated maintenance on 

a series of identified fuel breaks on the 

OTA. These fuel breaks are designed to 

act as barriers to prevent fires that might 

be ignited by military-training activities 

from spreading into adjacent L. 

papilliferum habitat (U.S. BLM 2008a, 

p. 20). 

Summary of Wildfire Management and 

Post-Wildfire Rehabilitation 

Wildfire management may have both 

positive consequences (the control of 

wildfires) and negative consequences 

(the destruction of slickspots or 

inadvertent introduction of invasive 

nonnative plants) for Lepidium 

papilliferum and its habitat, depending 

on how the activity is implemented. The 

negative consequences of wildfire 

management and rehabilitation 

activities appear to be relatively limited 

in both scope and severity, however, 

and we do not consider these negative 

effects to outweigh the positive effects 

of successful wildfire control, given that 

we consider frequent wildfires to be one 

of the primary threats to the species. On 

balance, wildfire and post-wildfire 

rehabilitation activities likely improve 

the status of the species. We therefore 

do not consider wildfire management or 

post-wildfire rehabilitation activities to 

be a significant threat to L. papilliferum. 

Military Training 

Military activities within the range of 

Lepidium papilliferum include 

ordnance-impact areas, training 

activities, and military development. 

Military-training activities occur at, or 

near, 4 of 80 extant EOs: 3 at the OTA 

on the Snake River Plain, and a portion 

of 1 EO at the Juniper Butte Range on 

the Owyhee Plateau. INRMPs have been 

developed and implemented for both 

the Juniper Butte Range and the OTA. 

The INRMPs provide management 

direction and conservation measures to 

address or eliminate the effects from 

military-training exercises on L. 

papilliferum and its habitat. Both the 

IDARNG (Quinney 2008; ICDC 2008, p. 

21) and the U.S. Air Force (CH2MHill 

2008a, pp. 1, 17) conduct annual 

monitoring to ensure impacts to the 

species due to training activities are 

either avoided or minimized. The 

IDARNG has implemented conservation 

measures for 18 years on the OTA, 

which currently supports nearly 60 

percent of the highest-quality habitat 

rangewide (B-ranked, EO 27). This 

suggests that the conservation measures 

are effective in maintaining generally 

intact native plant vegetation and 

limiting anthropogenic disturbances on 

the OTA since it contains much of the 

best remaining habitat for L. 

papilliferum (Sullivan and Nations 

2009, p. 91). 

Summary of Military Training 

The IDARNG and the U.S. Air Force 

continue to implement conservation 

efforts to avoid or reduce adverse effects 

of military training on Lepidium 

papilliferum and its habitat. Since the 

areas managed by the IDARNG and the 

U.S. Air Force continue to support some 

of the highest-quality habitat remaining 

for L. papilliferum, we consider the 

measures to minimize the impact of 

military-training exercises on the 

species and its habitat to have been 

effective. The IDARNG and U.S. Air 

Force are committed to continuing the 

implementation of these conservation 

measures into the future, through the 

CCA and their respective INRMPs. The 

threat of military training is localized in 

area, and minimal in significance across 

the range of the species, therefore we do 

not consider military training to pose a 

significant threat to L. papilliferum. 

Recreation 

Recreational activities that may affect 

Lepidium papilliferum include hiking, 

cycling, horseback riding, and the use of 

ORVs. These activities would be 

expected to impact the species primarily 

through mechanical disturbance (e.g., 

disruption of the slickspot soil layers, 

resulting in the reduction or loss of 

slickspot integrity and function) or 

crushing of individual plants, 

potentially resulting in injury or 

mortality. Areas where military training 

activities occur, such as the Juniper 

Butte Range and some areas of the OTA, 

are restricted from recreational activities 

because of military use. 

ORV use has been documented in 22 

of the 80 Lepidium papilliferum EOs (8 

of 16 on the Boise Foothills, 14 of 42 on 

the Snake River Plain, and none on the 

Owyhee Plateau) for which habitat 

information has been collected (Cole 

2009b, pp. 1-2). Effects from recreational 

activities, such as mechanical 

disturbance of soils from ORV use, are 

monitored as part of the rangewide HIP 

monitoring for L. papilliferum. ORV 

tracks were not detected in any EO or 

Management Area during 2008 HIP 

monitoring (Colket 2009, p. 9). In 2007, 

ORV tracks were detected at 2 of the 80 

HIP transects sampled (ICDC 2008, p. 9). 

Dual-wheel truck tracks were also 

detected at 2 other transects. An earlier 

analysis of HII transects monitored 

between 1998-2001, and HIP transects 

during 2004-2006 indicated that ORV 

use was detected at only a few transects 

each year and that impacts appeared to 

be minimal. 

Cycling and pedestrian trails built 

nearby and through the middle of 

occupied slickspots in the Boise 

Foothills are anticipated to impact 

individual plants and slickspot 

hydrology through trampling and spread 

of invasive nonnative plants in EO 38 

near the Ada County Landfill (Cole 

2008, p. 14). We have no other 

information to indicate that hiking or 

horseback riding have resulted in 

rangewide adverse impacts to L. 

papilliferum. 

Summary of Recreation 

Although recreational use has the 

potential for some negative effects on 

Lepidium papilliferum, the evidence 

indicates that observed impacts to 

Lepidium papilliferum from hiking, 

cycling, and ORV use have been 

minimal, and are infrequent and 

localized. While there is one EO being 

impacted by cycling and pedestrian 

trails, there is no information indicating 

that other recreational activities are 

impacting the species throughout its 

range, or that recreational usage within 

EOs is expected to increase. Recreation 

does not appear to be a major factor 

impacting either L. papilliferum or its 

slickspot habitat, therefore we have 

determined that recreation represents a 

minor threat to the species. 

Conclusion for Factor A 

Rationale 

Based on the best scientific data 

currently available, the primary 

significant threats to Lepidium 

papilliferum are the effects of the 

modified wildfire regime and invasive 

nonnative plants, especially Bromus 

tectorum. These threats are impacting 

the quality and composition of the 

sagebrush-steppe ecosystem where L. 

papilliferum occurs, and are degrading 

the species’ unique slickspot microsite 

habitats. These changes are associated 

with observed, significant decreases in 

the abundance of L. papilliferum. The 

observed increase in invasive annual 

grasses such as B. tectorum in the Great 

Basin, which includes the range of L. 

papilliferum, has resulted in increased 

frequency and extent of wildfires in L. 

papilliferum’s native-sagebrush systems; 

fires that once naturally occurred every 

100 years now occur on the order of 

every 5 years or less. The frequent 

return intervals of wildfire prevent the 

native sagebrush community from 

regenerating, and the habitat cannot 

achieve the late seral stage condition 

that represents high-quality habitat for 

L. papilliferum. The increased 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52043 

frequency of wildfires also results in the 

reduction of native plant diversity and 

species richness, and invasive 

nonnative plant cover increases in the 

wake of fire. Not only is this increase in 

nonnative plants being observed in the 

surrounding sagebrush matrix, but 

nonnative plants are increasingly 

invading the formerly sparsely vegetated 

slickspots, resulting in competitive 

exclusion of L. papilliferum. The 

combination of wildfire and nonnative 

plants additionally impacts slickspots 

by damaging the microbiotic crust and 

increasing sedimentation and organic 

matter, which hinders germination of L. 

papilliferum. Slickspots possess unique 

edaphic and hydrological properties, 

and represent a limited habitat resource 

on the landscape. As L. papilliferum is 

adapted to the specialized properties of 

slickspots, the degradation of slickspots 

to the point that they no longer provide 

the essential functions that support L. 

papilliferum represents a permanent 

loss of habitat for the species. 

We have new information indicating 

a statistically significant negative 

association between the abundance of 

Lepidium papilliferum and wildfire, and 

a significant negative association 

between L. papilliferum abundance and 

percent cover of B. tectorum in the 

surrounding plant community; these 

negative associations are consistent 

throughout the range of the species. 

Wildfire occurs throughout the range of 

L. papilliferum and has dramatically 

increased in both frequency and extent, 

especially where B. tectorum is 

dominant. Furthermore, as B. tectorum 

and other nonnative annual grasses 

continue to spread and degrade the 

sagebrush-steppe ecosystem, we expect 

continued increases in fire frequency 

and magnitude, with associated negative 

impacts on L. papilliferum. As 

disturbances such as wildfire remove 

sagebrush and encourage the spread of 

nonnative annual grasses, we anticipate 

that the Owyhee harvester ant will 

expand into areas occupied by L. 

papilliferum, resulting in an increase in 

seed predation on L. papilliferum, with 

potential negative consequences for 

plant reproduction and the maintenance 

of the persistent seed bank (see Disease 

and Predation section below). Future 

development of the sagebrush-steppe 

habitat also threatens many of the 

remaining L. papilliferum sites, and is of 

particular concern in the Boise Foothills 

region, which supports the highestdensity populations of L. papilliferum. 

Slickspots are relic Pleistocene 

formations and possess unique 

properties that likely cannot be 

recreated; slickspots lost to 

development represent a permanent loss 

of habitat for L. papilliferum. 

Given the observed negative 

association between the abundance of 

Lepidium papilliferum and the 

increased frequency of fire, as well as 

the demonstrated negative impacts of 

frequent, recurrent fire on the 

components that provide high-quality 

habitat for L. papilliferum, such as late 

seral stage sagebrush and high 

microbiotic crust cover, we consider the 

current wildfire regime to pose a 

significant and primary threat to L. 

papilliferum. Recurrent fire additionally 

promotes the continued invasion of 

nonnative annual grasses and other 

invasive nonnative plants. Given the 

observed negative association between 

the abundance of L. papilliferum and 

invasive nonnative plants both within 

slickspot microsites and in the 

surrounding plant community, the 

demonstrated ability of some nonnative 

plants to displace L. papilliferum from 

slickspots, the potential for nonnative 

grasses to facilitate the expansion of 

Owyhee harvester ants and thus 

increase seed predation on L. 

papilliferum, and the recognized 

contribution of nonnative plants such as 

B. tectorum to the increased fire 

frequency that poses a primary threat to 

the species, we consider invasive 

nonnative plants to pose a significant 

and primary threat to L. papilliferum as 

well. Although conservation measures 

have been implemented in an attempt to 

protect L. papilliferum and its habitat 

from these threats, at present the 

challenge of controlling and preventing 

the further spread of invasive nonnative 

plants and wildfire is too great for these 

measures to effectively reduce the 

degree of threat to the species across its 

range. Based on the demonstrated 

increases in nonnative plant cover in 

areas occupied by L. papilliferum, 

including slickspot microsites, the 

observed continuing increases in B. 

tectorum, observed increases in the 

frequency and extent of wildfires 

through the range of the species, and the 

lack of effective control mechanisms, we 

expect the degree of the threat from 

wildfire and invasive nonnative plant 

species to continue and likely increase 

within the foreseeable future. 

Development poses a somewhat lesser 

threat to the species. Although the 

impact of development can be severe, in 

that habitat conversion for residential, 

commercial, or agricultural 

development most often results in the 

permanent loss of slickspot habitat, the 

areas likely to be developed represent a 

relatively small portion of the species’ 

range. The area most likely to be 

developed is, however, the area that 

supports some of the highest-density 

populations of Lepidium papilliferum. 

Other planned development projects, 

such as utility rights of way, can impact 

L. papilliferum by facilitating the 

increase of invasive nonnative plants 

and increasing the risk of human-caused 

wildfires, as well as through habitat 

fragmentation, isolation of populations, 

and potential reductions in insect 

pollinators. We consider development 

to pose a moderate degree of threat to 

Lepidium papilliferum, particularly for 

those populations in the Boise Foothills 

and the Snake River Plain 

physiographic regions. 

We additionally considered whether 

livestock use, wildfire management and 

post-wildfire rehabilitation, military 

training, or recreation pose a threat to 

Lepidium papilliferum through the 

present or threatened destruction, 

modification, or curtailment of its 

habitat or range. In the case of livestock 

use, the best available data indicate that 

although livestock have the potential to 

pose a threat to L. papilliferum, at 

present this threat appears to be 

seasonal and localized in nature. The 

continued maintenance of implemented 

conservation measures to protect L. 

papilliferum from inappropriate 

livestock use will be important in 

ameliorating the effects of this threat. 

We do not consider livestock use to 

pose a significant threat to the species 

at this time. The effects associated with 

wildfire management and post-wildfire 

rehabilitation, military training, and 

recreation are all positive or relatively 

minimal, and we do not consider any of 

these activities to pose a significant 

threat to L. papilliferum. 

Determination for Factor A 

We have evaluated the best available 

scientific information on the present or 

threatened destruction, modification or 

curtailment of Lepidium papilliferum’s 

habitat or range, and determined that 

this factor poses a significant threat to 

the viability of the species throughout 

its range, such that we anticipate L. 

papilliferum is likely to become an 

endangered species within the 

foreseeable future. 

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 

We have no data indicating that 

disease poses a threat to Lepidium 


srobinson on DSKHWCL6B1PROD with RULES4
52044 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

papilliferum. On the other hand, though 

insect and mammal herbivory do not 

appear to pose a threat to Lepidium 

papilliferum, seed predation by the 

Owyhee harvester ant may become a 

significant threat to the species. 

Insect herbivory of Lepidium 

papilliferum has been evaluated as part 

of pollinator and reproductive studies 

the past several years. The most 

abundant insect herbivore was a 

chrysomelid beetle, Phyllotreta sp., 

which chews holes in the flower’s petals 

(Leavitt and Robertson 2006, pp. 658- 

659). Lepidium papilliferum flowers 

suffering damage from Phyllotreta (a 

hole chewed in a single petal) have been 

documented to set seed at a significantly 

lower rate than undamaged flowers on 

the same plant. Overall, herbivory of L. 

papilliferum petals by chrysomelid 

beetles reduces the effectiveness of 

insect-mediated pollination, but does 

not physically inhibit pollination or 

seed production. The effect of herbivory 

by chrysomelid beetles appears to be 

limited in its impact on the species, and 

we do have not evidence suggesting that 

it poses a significant threat to L. 

papilliferum at this time. 

The Owyhee harvester ant was 

recently identified as a potentially 

important seed predator of Lepidium 

papilliferum. A study initiated in 2006 

found that following L. papilliferum’s 

flowering season, Owyhee harvester 

ants remove the mature, seed-bearing 

fruits and return them to their nests 

outside of slickspots (Robertson and 

White 2007, pp. 8-13). The researchers 

found that harvester ants can remove up 

to 90 percent of L. papilliferum fruits 

and seeds, either directly from the plant 

or by scavenging seeds that drop to the 

ground (Robertson and White 2009, p. 

9). Seventy-five percent of slickspots 

with flowering L. papilliferum located 

within 66 ft (20 m) of a harvester ant 

nest showed evidence of seed predation; 

the researchers suggest this is the 

maximum foraging distance for the 

Owyhee harvester ant (Robertson and 

White 2009, p. 10). Slickspots with high 

densities of flowering L. papilliferum 

were also observed as more likely to 

show evidence of seed predation than 

those with low densities (Robertson and 

White 2007, p. 13). Because harvester 

ants consume seeds of other plant 

species as well, most notably Bromus 

tectorum, L. papilliferum seeds are 

likely an opportunistic food item rather 

than an essential part of their diet 

(Robertson and White 2007, p. 12). 

Owyhee harvester ants have been 

observed bypassing seeds of B. tectorum 

in favor of L. papilliferum seeds 

(Robertson and White 2009, pers. 

comm.), but whether the seeds of L. 

papilliferum are preferred or may just be 

taken based on relatively greater 

seasonal availability is not yet known 

(Robertson 2009, pers. comm.). 

The Owyhee harvester ant is a species 

native to Southwest Idaho; therefore, it 

might be assumed that Lepidium 

papilliferum co-evolved with the ant 

and has adapted to adjust for the 

observed levels of seed predation. 

Evidence suggests, however, that 

harvester ant colonies were likely not 

numerous in the intact sagebrush-steppe 

habitat that has historically surrounded 

L. papilliferum in its slickspot 

microsites. White and Robertson (2008, 

p. 3) found that Owyhee harvester ant 

colonies are uniformly low in number in 

areas with high sagebrush cover, while 

densities are highest in the study areas 

with little sagebrush cover. By contrast, 

Owyhee harvester ant colonies range 

from uncommon to very common in 

areas dominated by annual grasses 

(Robertson and White 2009, p. 13), 

which would include Bromus tectorum. 

The study authors suggest that sites 

dominated by annual grasses but with 

low harvester ant numbers may 

represent areas that the ants have yet to 

colonize, or the habitat is unsuitable for 

reasons other than vegetation (Robertson 

and White 2009, p. 13). They further 

suggest that the observed shift from 

sagebrush to annual grasses may enable 

the ants to colonize areas that were 

historically not suitable for nesting, 

with potentially negative consequences 

for L. papilliferum (Robertson and 

White 2009, p. 13). 

Since Owyhee harvester ants are more 

common in disturbed areas with an 

abundance of B. tectorum (White and 

Robertson 2008, pp. 3-4), this raises a 

conservation concern for Lepidium 

papilliferum. As landscape disturbances 

such as wildfire are contributing to the 

loss or conversion of sagebrush habitats 

to annual grasslands, and these 

grasslands are likely to support higher 

densities of Owyhee harvester ants, 

these disturbances are likely 

contributing to an increase in the 

abundance and distribution of the 

harvester ants throughout L. 

papilliferum’s geographic range. 

Furthermore, since these ants have been 

observed to harvest up to 90 percent of 

the seeds produced by L. papilliferum, 

increased predation by harvester ants, 

even at much lower levels than 90 

percent, has the potential to 

significantly depress the reproductive 

capacity of the plant, as well as 

diminish the capacity to replenish the 

species seedbank. However, as this 

threat was only recently discovered, we 

have no information indicating what the 

actual magnitude or severity of this 

threat might be. In addition, no 

conservation measures have yet been 

attempted to ameliorate the threat of 

seed predation by the Owyhee harvester 

ant, and the researchers have urged 

caution in taking such measures until 

managers have a better understanding of 

the threat (Robertson and White 2009, p. 

14). 

The OTA’s ‘‘Red Tie’’ population of 

Lepidium papilliferum (EO 27) presents 

an interesting example of the potential 

threat posed by Owyhee harvester ants, 

and their apparent preferred association 

with grasses. Much of the Red Tie site 

is currently dominated by sagebrush 

(Artemisia tridentata ssp. tridentata), 

with L. papilliferum–occupied 

slickspots scattered throughout the 

sagebrush matrix. Currently, there is no 

evidence of contact between L. 

papilliferum and Owyhee harvester ants 

throughout most of the site where 

sagebrush dominates. The exception is 

at the periphery, where the vegetation 

transitions from sagebrush to a more 

open, grassland area. It was at this 

transition of habitat from sagebrush to 

grasslands where three active harvester 

ant colonies were found in 2008 (White 

and Robertson 2008, p. 4). The authors 

of this study caution that disturbances 

such as fire that remove sagebrush and 

promote the invasion of annual grasses 

may create conditions that promote the 

expansion of the harvester ants into 

areas currently occupied by L. 

papilliferum, resulting in increased seed 

predation throughout the range of the 

species (White and Robertson 2008, p. 

4). Future HIP monitoring will examine 

proximity and density of Owyhee 

harvester ant colonies to L. papilliferum 

transects to track this potential new 

threat (Colket 2009, pers. comm.). 

Herbivory impacts to Lepidium 

papilliferum from large, native 

ungulates, such as elk, deer, and 

antelope, have not been observed. 

Statistical analyses of wild ungulate 

hoofprint cover in slickspots from 2004- 

2008 HIP monitoring data showed no 

relationship with L. papilliferum 

abundance (Sullivan and Nations 2009, 

p. 122). Sullivan and Nations (2009, p. 

122) likewise found no association 

between the cover of livestock hoof 

prints and L. papilliferum abundance. 

Domestic cattle are not known to feed 

upon L. papilliferum, and domestic 

sheep have been observed pulling plants 

from the ground and spitting them out 

(Quinney and Weaver 1998, pers. 

comm.). Herbivory by large ungulates, 

whether wild or domestic, thus does not 

appear to pose a threat to L. 

papilliferum. 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52045 

Summary of Disease or Predation 

Herbivory by chrysomelid beetles and 

by large ungulates, whether wild or 

domestic, does not appear to pose a 

significant threat to Lepidium 

papilliferum. Herbivory in the form of 

seed predation by Owyhee harvester 

ants, which was only recently 

discovered, appears to pose a 

potentially significant threat to the 

species. In one study, ants were 

observed to be capable of removing up 

to 90 percent of L. papilliferum fruits or 

seeds from slickspots within 66 ft (20 m) 

of a nest (Robertson and White 2009, p. 

9). As the ants appear to favor the 

conditions created by the introduction 

of annual grasses, and the cover of 

annual grasses is expanding in L. 

papilliferum habitat, the increase in 

seed predation as a consequence of 

harvester ants moving into areas 

adjacent to occupied slickspots has the 

potential to significantly impact L. 

papilliferum recruitment and the 

replenishment of the seed bank. While 

this may be a minor threat at this point 

in time, given the projected increase in 

nonnative annual grasslands within the 

range of L. papilliferum and the 

apparent positive association between 

Owyhee harvester ants and grasslands, 

we believe this has the potential to 

become a significant threat to L. 

papilliferum in the foreseeable future. 

Conclusion for Factor C 

Rationale 

The effect of seed predation by 

Owyhee harvester ants is an emerging 

threat potentially affecting the long-term 

viability of Lepidium papilliferum. In 

areas where Owyhee harvester ants have 

become established, L. papilliferum 

could be depleted through lack of 

seedling recruitment. However, at this 

point in time we do not yet have enough 

research to determine whether the seed 

bank is being negatively affected by seed 

predation from harvester ants. The fact 

that harvester ant colonies appear to be 

found in higher numbers in annual 

grasslands, which are in turn increasing 

as the result of increased wildfire and 

the spread of nonnative grasses such as 

Bromus tectorum, suggests that the 

degree of this potential threat is likely 

to increase in the future. Our current 

understanding of how pervasive 

harvester ant colonies have become 

within the range of L. papilliferum, and 

their overall significance on the longterm viability of the species, is limited 

due to the short-term nature of the study 

results available thus far. The evidence 

suggests, however, that significant levels 

of seed predation associated with 

increased abundance and range of 

Owyhee harvester ants has the potential 

to pose a significant threat to L. 

papilliferum in the foreseeable future. 

This potential threat is pervasive 

throughout the range of L. papilliferum. 

Determination for Factor C 

We have evaluated the best available 

scientific information on the effects of 

disease or predation on Lepidium 

papilliferum, and determined that this 

factor poses a significant threat to the 

viability of the species throughout its 

range, such that we anticipate that L. 

papilliferum is likely to become an 

endangered species within the 

foreseeable future, when we consider 

this factor in concert with the other 

factors impacting the species. 

D. Inadequacy of Existing Regulatory 

Mechanisms 

Few existing regulatory mechanisms 

apply to Lepidium papilliferum. At the 

Federal level, Lepidium papilliferum is 

currently categorized as a Type 1 

sensitive species by BLM (U.S. BLM 

2003, p. 1; Rinkes 2009, pers. comm.). 

The BLM has regulations that address 

the need to protect sensitive, candidate, 

and federally listed species. The BLM is 

the primary land-management agency 

implementing conservation efforts for 

this species, and continues to monitor L. 

papilliferum on the Federal lands it 

manages. 

At the State level, Idaho Code 18-3911 

protects a selected list of wildflowers, 

but Lepidium papilliferum is not one of 

the species listed. The protection 

allowed under Idaho Code 18-3911 

basically makes it unlawful to export or 

offer for sale plants or parts of plants 

that are on the list of protected plants. 

As we have no information indicating 

that the export or sale of L. papilliferum 

poses a threat to the species, we do not 

consider the fact that L. papilliferum is 

not protected under Idaho Code 18-3911 

to pose a significant threat to the 

species. 

Conclusion for Factor D 

Rationale 

The inadequacy of existing regulatory 

mechanisms does not appear to pose a 

threat to Lepidium papilliferum. The 

BLM manages L. papilliferum as a 

sensitive species, according to that 

agency’s regulations, and continues to 

implement conservation efforts, as well 

as monitor the species, on lands under 

its management. Although the State of 

Idaho does not extend protections 

against export or sale to L. papilliferum 

under Idaho Code 18-3911, the lack of 

protection not appear to pose a 

significant threat to the species, as we 

have no information indicating that the 

species is subject to export or sale. 

However, we note that Idaho Code 18- 

3913 provides the Idaho Department of 

Fish and Game with authority to amend 

the list of protected wildflowers, so L. 

papilliferum could be protected as 

specified in Idaho Code 18-3911. 

Determination for Factor D 

We have evaluated the best available 

information regarding the potential 

inadequacy of existing regulatory 

mechanisms and their effect on 

Lepidium papilliferum, and determined 

that this factor does not pose a 

significant threat to the viability of the 

species. 

E. Other Natural or Manmade Factors 

Affecting Its Continued Existence 

Precipitation Patterns 

Studies have indicated that the 

density and abundance of Lepidium 

papilliferum is positively correlated 

with levels of winter-spring (roughly 

January to March) precipitation (Palazzo 

et al. 2005, p. 9; Meyer et al. 2005, p. 

15; Menke and Kaye 2006a, p. 8, 2006b 

pp. 10-11; CH2MHill 2007a, p. 14; 

Sullivan and Nations 2009, pp. 40-41), 

and negatively correlated with fallwinter (roughly October to December) 

precipitation (Meyer et al. 2005, pp. 15- 

16; Sullivan and Nations 2009, pp. 37- 

45). To assess the possibility that the 

negative trend in L. papilliferum density 

observed on the rough census plots at 

the OTA by Sullivan and Nations (2009, 

p. 39) may be due, at least in part, to 

either a corresponding negative trend in 

spring precipitation or a corresponding 

positive trend in winter precipitation at 

the OTA, we performed a least squares 

linear regression analysis (a statistical 

method to discern a potentially 

significant relationship between two 

variables, in this case whether there was 

any trend in rainfall over time) on 

monthly precipitation data available for 

the years 1991 through 2007 (Zwartjes 

2009). Similar to the simple linear 

model employed by Sullivan and 

Nations (2009, p. 38) in their analysis to 

assess whether there was any general, 

overall trend in population numbers 

over time, this exercise was intended 

only to determine whether there might 

have been any significant general trend 

in precipitation levels during the time 

period of interest, not to explain the 

potentially complex patterns of 

precipitation over time. According to 

the results, none of the precipitation 

parameters utilized (modeled to be 

consistent with those utilized by 

Sullivan and Nations 2009)—total 

annual precipitation, total precipitation 

for the spring months (analyzed in three 


srobinson on DSKHWCL6B1PROD with RULES4
52046 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

time blocks as the sum of precipitation 

in February through May, February 

through June, and March through May), 

total precipitation for the winter months 

(October through December), or monthly 

precipitation based on 3–month moving 

averages from January to March through 

December to February — produced 

results suggesting that any of the 

precipitation trends over these years 

were significantly different statistically 

from a slope of zero (Zwartjes 2009, 

Figures 1-17, Appendix). Based on this 

simple model, there does not appear to 

be any general trend in precipitation 

over the years 1991 through 2007, either 

positive or negative, that corresponds 

with the observed negative trend in L. 

papilliferum density at the OTA over 

the years 1990 through 2008 as 

identified by Sullivan and Nations 

(2009) (Zwartjes 2009, p. 1). 

Summary of Precipitation Patterns 

The annual abundance of Lepidium 

papilliferum varies annually in concert 

with the level of precipitation; there 

appears to be a negative relationship 

between high winter precipitation and 

L. papilliferum abundance the following 

spring, and a positive relationship 

between spring precipitation and L. 

papilliferum abundance. One possible 

explanation for the observed significant 

decline in L. papilliferum abundance 

over time at the OTA rough census areas 

is that there was a similar trend in 

precipitation over that same time period 

(a decrease in spring precipitation, an 

increase in winter precipitation, or 

both). We did not, however, find any 

significant trend in precipitation in the 

same time frame. Thus, any changes in 

the abundance or density of L. 

papilliferum appear to have occurred 

independently of any trend in 

precipitation. Therefore, similar to our 

2007 finding, we do not consider the 

current precipitation pattern to pose an 

extinction risk to the species. 

Habitat Fragmentation and Isolation of 

Small Populations 

Due to its occupancy of patchily 

distributed slickspots, the habitat of 

Lepidium papilliferum is somewhat 

naturally fragmented. Fragmentation at 

a larger scale, however, can pose 

problems for L. papilliferum by creating 

barriers in the landscape that prevent 

effective genetic exchange between 

populations. Seed dispersal for L. 

papilliferum likely occurs only over 

very short distances; thus, pollinators 

and pollen dispersal are the primary 

means for reproductive and genetic 

exchange between L. papilliferum sites 

(Robertson and Ulappa 2004, pp. 1705, 

1708; Stillman et al. 2005, pp. 1, 6-8). 

Research indicates that seeds generated 

by the pollination of nearby plants have 

reduced viability, and that L. 

papilliferum seed viability increases as 

the distance to the contributing 

pollination source increases (Robertson 

and Ulappa 2004, pp 1705, 1708). The 

ability to exchange pollen with distant 

populations is therefore an advantage 

for L. papilliferum. Barriers or too much 

distance between slickspots and 

pollinating insect habitats can reduce 

the effective range of insects important 

to L. papilliferum pollination (Robertson 

et al. 2004, pp. 2-4). Barriers can include 

agricultural fields, urban development, 

and large areas of annual and perennial 

grass monocultures that do not support 

diversity and suitable floral resources 

such as nectar or edible pollen for 

pollinators. Lepidium papilliferum 

habitats separated by distances greater 

than the effective range of available 

pollinating insects are at a genetic 

disadvantage, and may become 

vulnerable to the effects of loss of 

genetic diversity (Stillman et al. 2005, 

pp. 1, 6-8) and a reduction in seed 

production (Robertson et al. 2004, p. 

1705). A genetic analysis of L. 

papilliferum suggested that populations 

in the Snake River Plain and the 

Owyhee Plateau ‘‘may have reduced 

genetic diversity’’ (Larson et al. 2006, p. 

17; note the Boise Foothills were not 

analyzed separately in this study). 

Many of the remaining occurrences of 

Lepidium papilliferum, particularly in 

the Snake River Plain near urban 

centers, are restricted to small, remnant 

patches of suitable sagebrush-steppe 

habitat. When last surveyed, 31 EOs (37 

percent) each had fewer than 50 plants 

(Colket et al. 2006, Tables 1 to 13). 

Many of these small remnant EOs exist 

within habitat that is degraded by the 

factors identified above. Small L. 

papilliferum populations have likely 

persisted due to their long-lived seed 

bank, but the potential risk of depletion 

of each population’s seed bank with no 

new genetic input makes the persistence 

of these small populations uncertain. 

Providing suitable habitats and foraging 

habitats for the species’ insect 

pollinators is important for maintaining 

L. papilliferum genetic diversity. Small 

populations are vulnerable to relatively 

minor environmental disturbances such 

as wildfire, herbicide drift, and 

nonnative plant invasions (Given 1994, 

pp. 66-67), and are subject to the loss of 

genetic diversity from genetic drift and 

inbreeding (Ellstrand and Elam 1993, 

pp. 217-237). Populations with lowered 

genetic diversity are more prone to local 

extinction (Barrett and Kohn 1991, pp. 

4, 28). Smaller populations generally 

have lower genetic diversity, and lower 

genetic diversity may in turn lead to 

even smaller populations by decreasing 

the species’ ability to adapt, thereby 

increasing the probability of population 

extinction (Newman and Pilson 1997, p. 

360). 

Fragmentation (either by development 

or wildfires) has occurred in 62 of the 

79 EOs for which habitat information is 

known (15 of 16 on the Boise Foothills, 

35 of 42 on the Snake River Plain and 

12 of 21 on the Owyhee Plateau), and 

78 EOs (all except one on the Owyhee 

Plateau) have fragmentation occurring 

within 0.31 mi (500 m) of the EOs (Cole 

2009b, Threats Table). Additionally, as 

described above in Factor A, 

Development, several development 

projects are planned within the 

occupied range of Lepidium 

papilliferum that would contribute to 

further large-scale fragmentation of its 

habitat, potentially resulting in 

decreased viability of populations 

through decreased seed production, 

reduced genetic diversity, and the 

increased inherent vulnerability of 

small populations to localized 

extirpation. 

Summary of Habitat Fragmentation and 

Isolation of Small Populations 

Even though Lepidium papilliferum 

occurs in naturally patchy microsite 

habitats, the increasing degree of 

fragmentation produced by wildfires 

and development may result in the 

separation of populations beyond the 

distance that its insect pollinators are 

capable of traveling. Genetic exchange 

in L. papilliferum is achieved through 

either seed dispersal or insect-mediated 

pollination, and plants that receive 

pollen from more distant sources 

demonstrate greater reproductive 

success in terms of seed production. As 

all indications are that seeds are 

dispersed over only a very small 

distance and insect pollinators are also 

limited in their dispersal capabilities, 

habitat fragmentation and isolation of 

populations poses a threat to L. 

papilliferum in terms of decreased 

reproductive success (lower seed set), 

reduced genetic variability, and greater 

local extinction risk. For these reasons 

we consider habitat fragmentation 

resulting from wildfires and 

development to pose a moderate degree 

of threat to Lepidium papilliferum. We 

consider this threat to be significant, but 

not as severe as the threats posed by the 

modified wildfire regime and invasive 

nonnative plant species. The threat of 

habitat fragmentation and isolation of 

small populations is pervasive 

throughout the range of L. papilliferum. 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52047 

Climate Change 

The Intergovernmental Panel on 

Climate Change (IPCC) was established 

in 1988 by the World Meteorological 

Organization and the United Nations 

Environment Program in response to 

growing concerns about climate change 

and, in particular, the effects of global 

warming. Although the extent of 

warming likely to occur is not known 

with certainty at this time, the IPCC has 

concluded that warming of the climate 

is unequivocal, and that continued 

greenhouse gas emissions at or above 

current rates will cause further warming 

(IPCC 2007, p. 30). Eleven of the 12 

years from 1995 through 2006 rank 

among the 12 warmest years in the 

instrumental record of global surface 

temperature since 1850 (ISAB 2007). 

Climate-change scenarios estimate that 

the mean air temperature could increase 

by over 3 degrees Celsius (5.4 degrees 

Fahrenheit) by 2100 (IPCC 2007, p. 46). 

The IPCC also projects that there will 

very likely be regional increases in the 

frequency of hot extremes, heat waves, 

and heavy precipitation (IPCC 2007, p. 

46), as well as increases in atmospheric 

carbon dioxide (IPCC 2007, p. 36). 

We recognize that there are scientific 

differences of opinion on many aspects 

of climate change, including the role of 

natural variability in climate. In our 

analysis, we rely primarily on synthesis 

documents (e.g., IPCC 2007, Karl et al. 

2009) that present the consensus view of 

a very large number of experts on 

climate change from around the world. 

We have found that these synthesis 

reports, as well as the scientific papers 

used in those reports or resulting from 

those reports, represent the best 

available scientific information we can 

use to inform our decision and have 

relied upon them and provided citation 

within our analysis. In addition, where 

possible we have utilized projections 

specific to the region of interest, the 

Great Basin, which includes the range of 

Lepidium papilliferum. 

Projected climate change and its 

associated consequences have the 

potential to affect Lepidium 

papilliferum and may increase its risk of 

extinction, as the impacts of climate 

change interact with other stressors 

such as habitat degradation and loss that 

are already affecting the species (Karl et 

al. 2009, p. 81). In the Pacific 

Northwest, regionally averaged 

temperatures have risen 0.8 degrees 

Celsius (1.5 degrees Fahrenheit) over the 

last century (as much as 2 degrees 

Celsius (4 degrees Fahrenheit) in some 

areas), and are projected to increase by 

another 1.5 to 5.5 degrees Celsius (3 to 

10 degrees Fahrenheit) over the next 100 

years (Mote et al. 2003, p. 54; Karl et al. 

2009, p. 135). Arid regions such as the 

Great Basin where L. papilliferum 

occurs are likely to become hotter and 

drier; fire frequency is expected to 

accelerate, and fires may become larger 

and more severe (Brown et al. 2004, pp. 

382-383; Neilson et al. 2005, p. 150; 

Chambers and Pellant 2008, p. 31; Karl 

et al. 2009, p. 83). Under projected 

future temperature conditions, the cover 

of sagebrush in the Great Basin region 

is anticipated to be dramatically 

reduced (Neilson et al. 2005, p. 154). 

Warmer temperatures and greater 

concentrations of atmospheric carbon 

dioxide create conditions favorable to 

Bromus tectorum, as described below, 

thus continuing the positive feedback 

cycle between the invasive annual grass 

and fire frequency that poses a 

significant threat to L. papilliferum 

(Chambers and Pellant 2008, p. 32; Karl 

et al. 2009, p. 83). 

Emissions of carbon dioxide, 

considered to be the most important 

anthropogenic greenhouse gas, 

increased due to human activities by 

approximately 80 percent between 1970 

and 2004 (IPCC 2007, p. 36). Future 

carbon dioxide emissions from energy 

use are projected to increase by 40 to 

110 percent over the next few decades, 

between 2000 and 2030 (IPCC 2007, p. 

44). An increase in the atmospheric 

concentration of carbon dioxide has 

important implications for Lepidium 

papilliferum, beyond those associated 

with warming temperatures, because 

higher concentrations of carbon dioxide 

are favorable for the growth and 

productivity of Bromus tectorum (Smith 

et al. 1987, p. 142; Smith et al. 2000, p. 

81). Although most plants respond 

positively to increased carbon dioxide 

levels, many invasive nonnative plants 

respond with greater growth rates than 

native plants, including B. tectorum 

(Smith et al. 1987, p. 142; Smith et al. 

2000, p. 81; Karl et al. 2009, p. 83). 

Laboratory research results illustrated 

that B. tectorum grown at carbon 

dioxide levels representative of current 

climatic conditions matured more 

quickly, produced more seed and 

greater biomass, and produced 

significantly more heat per unit biomass 

when burned than B. tectorum grown at 

‘‘pre-industrial’’ carbon dioxide levels 

(Blank et al. 2006, pp. 231, 234). These 

responses to increasing carbon dioxide 

may have increased the flammability in 

B. tectorum communities during the 

past century (Ziska et al. 2005, as cited 

in Zouhar et al. 2008, p. 30; Blank et al. 

2006, p. 234). 

Field studies likewise demonstrate 

that Bromus species demonstrate 

significantly higher plant density, 

biomass, and seed rain (dispersed seeds) 

at elevated carbon dioxide levels 

relative to native annuals (Smith et al. 

2000, pp. 79-81). The researchers 

conclude that ‘‘the results from this 

study * * * confirm experimentally in 

an intact ecosystem that elevated carbon 

dioxide may enhance the invasive 

success of Bromus spp. in arid 

ecosystems,’’ and suggest that this 

enhanced success will then expose 

these areas to accelerated fire cycles 

(Smith et al. 2000, p. 81). Chambers and 

Pellant (2008, p. 32) also suggest that 

higher carbon dioxide levels are likely 

increasing B. tectorum fuel loads due to 

increased productivity, with a resulting 

increase in fire frequency and extent. 

Based on the best available information, 

we therefore expect continuing 

production of atmospheric carbon 

dioxide at or above current levels, as 

predicted, to increase the threat posed 

to L. papilliferum by B. tectorum and 

from more frequent, expansive, and 

severe wildfires (Smith et al. 1987, p. 

143; Smith et al. 2000, p. 81; Brown et 

al. 2004, p. 384; Neilson et al. 2005, pp. 

150, 156; Chambers and Pellant 2008, 

pp. 31-32). 

Bradley et al. (in press, pp. 1-11) 

predict that nonnative invasive species 

in the sagebrush-steppe ecosystem may 

either expand or contract under climate 

change, depending on the current and 

projected future range of a particular 

invasive plant species. They developed 

a bioclimatic model for Bromus 

tectorum based on maps of invaded 

range derived from remote sensing and 

on the climate variables that best predict 

species presence, and found that the 

best predictors of B. tectorum 

occurrence are summer, annual, and 

spring precipitation, followed by winter 

temperature (Bradley et al., in press, p. 

5). They then used projections of 10 

atmosphere-ocean, general-circulation 

models for the year 2100. Depending 

primarily on future precipitation 

conditions, the model predicts B. 

tectorum is likely to shift northwards, 

leading to expanded risk of B. tectorum 

invasion in Idaho, Montana, and 

Wyoming, but reduced risk of invasion 

in southern Nevada and Utah, which 

currently have large areas dominated by 

this nonnative grass (Bradley et al., in 

press, p. 5). Although the authors note 

that their models also predict some 

range contractions by B. tectorum by 

2100, much of southern Idaho where 

Lepidium papilliferum occurs appears 

to maintain large populations of B. 

tectorum (Figure 4, p. 7). The threat 

posed to L. papilliferum by the greater 

frequency and geographic extent of 

wildfires and other associated negative 


srobinson on DSKHWCL6B1PROD with RULES4
52048 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

impacts from the presence of B. 

tectorum is therefore expected to 

continue into the foreseeable future. 

An additional potential threat to 

Lepidium papilliferum resulting from 

climate change is the predicted change 

in precipitation patterns. Current 

projections for the Pacific Northwest 

region are that precipitation will 

increase in the winter but decrease in 

the summer months (Karl et al. 2009, p. 

135). The survivorship of L. 

papilliferum rosettes to flower the 

following spring is favored by greater 

summer precipitation (Meyer et al. 

2005, p. 15; CH2MHill 2007a, p. 14; 

Sullivan and Nations 2009, pp. 33, 41), 

and increased winter precipitation 

appears to decrease survivorship (Meyer 

et al. 2005, pp. 15-16; Sullivan and 

Nations 2009, pp. 39, 43-44). As the 

projected rainfall pattern under climate 

change would follow the opposite 

pattern, this alteration in seasonal 

precipitation could result in decreased 

survivorship of L. papilliferum. 

Alterations in precipitation patterns, 

however, are more uncertain than 

predicted changes in temperature for the 

Great Basin region (Neilson et al. 2005, 

p. 153). 

Summary of Climate Change 

The direct, long-term impact from 

climate change to Lepidium 

papilliferum is yet to be determined. 

However, as described under Factor A, 

above, the invasion of Bromus tectorum 

and the associated changes in fire 

regime currently pose one of the most 

significant threats to Lepidium 

papilliferum, the sagebrush-steppe 

ecosystem, and the slickspot habitats 

where L. papilliferum resides. Under 

current climate-change projections, we 

anticipate that future climatic 

conditions will favor further invasion by 

B. tectorum, that fire frequency will 

continue to increase, and the extent and 

severity of fires may increase as well. 

Precipitation patterns may also be 

altered as a result of climate change, 

resulting in potential decreased 

survivorship of L. papilliferum, 

although the projections for future 

precipitation patterns are less certain. 

The consequences of climate change, if 

current projections are realized, are 

therefore likely to exacerbate the 

existing primary threats to L. 

papilliferum of frequent wildfire and 

invasive nonnative plants, particularly 

B. tectorum. As the IPCC projects that 

the changes to the global climate system 

in the 21st century will likely be greater 

than those observed in the 20th century 

(IPCC 2007, p. 45), we anticipate that 

these effects will continue and likely 

increase into the foreseeable future. As 

there is some degree of uncertainty 

regarding the potential effects of climate 

change on L. papilliferum specifically, 

climate change in and of itself was not 

considered a significant factor in our 

determination to list L. papilliferum as 

a threatened species. However, we 

recognize that the severity and scope of 

the primary threats to L. papilliferum of 

frequent wildfire and B. tectorum are 

likely to magnify depending on the 

realized outcome of climate change 

within the foreseeable future; thus, we 

consider climate change as playing a 

potentially important supporting role in 

intensifying the primary current threats 

to the species. 

Conclusion for Factor E 

Rationale 

Habitat fragmentation that results 

from wildfires and development may 

result in the separation of Lepidium 

papilliferum populations beyond the 

distance that its insect pollinators can 

travel, and likely limits the ability for 

seeds to travel between populations as 

well. Limited genetic exchange due to 

fragmentation can result in reduced 

seed production for this species, as well 

as a loss of genetic diversity. Small, 

isolated populations with lowered 

genetic diversity are at increased risk of 

local extinction. Habitat fragmentation 

due to wildfires and various forms of 

development is occurring throughout 

the range of the species, and is expected 

to increase in the future. As the insect 

pollinators of L. papilliferum traverse 

relatively short distances, and evidence 

suggests that seed dispersal is limited as 

well, we consider the consequences of 

limited genetic exchange as a result of 

habitat fragmentation to pose a 

significant and moderate degree of 

threat to L. papilliferum throughout its 

range. Although significant, we do not 

consider the severity of this threat to 

reach the level of threat posed to L. 

papilliferum by the primary threats of 

the modified wildfire regime and 

invasive nonnative plant species. 

Current climate-change models 

predict future climatic conditions 

within the range of Lepidium 

papilliferum will favor further invasion 

by Bromus tectorum. These models also 

project that fire frequency will continue 

to increase and that the extent and 

severity of wildfires may increase as 

well. Thus, the consequences of 

projected, future climate change, if 

realized, are likely to further magnify 

the severity and scope of the primary 

significant threats to L. papilliferum. 

Due to the uncertainty associated with 

climate change projections, we do not 

consider climate change in and of itself 

to represent a significant threat to L. 

papilliferum. However, we acknowledge 

that climate change will likely play a 

potentially important supporting role in 

intensifying the most significant current 

threats to the species in the foreseeable 

future. The projected consequences of 

climate change would act to exacerbate 

the primary threats of frequent wildfire 

and invasive nonnative plant species to 

L. papilliferum throughout its range. 

The abundance of Lepidium 

papilliferum is closely associated with 

levels of rainfall, showing a positive 

association with high levels of spring 

precipitation and a negative association 

with high levels of winter precipitation. 

We thus considered whether the 

declining population trend in L. 

papilliferum might be a consequence of 

a corresponding trend in precipitation. 

We did not find evidence of any trend 

in precipitation for L. papilliferum for 

the time period for which we have 

evidence of the declining trend in 

density at the OTA; thus, we conclude 

that any population trend in L. 

papilliferum is independent of any 

trend in precipitation. Precipitation 

patterns were therefore not considered 

to pose a threat to the species. 

Determination for Factor E 

We have evaluated the best available 

scientific information on other natural 

or manmade factors affecting the 

continued existence of Lepidium 

papilliferum, including precipitation 

patterns, habitat fragmentation and 

isolation of small populations, and 

climate change, and determined that 

this factor poses a significant threat to 

the viability of the species throughout 

its range when considered in concert 

with Factor A, such that we anticipate 

that L. papilliferum is likely to become 

an endangered species within the 

foreseeable future. 

Evaluation of Conservation Efforts 

In making a determination as to 

whether any species is an endangered 

species or a threatened species, Section 

4(b)(1)(A) of the Act mandates that the 

Secretary shall make such 

determinations ‘‘solely on the basis of 

the best scientific and commercial data 

available to him after conducting a 

review of the status of the species and 

after taking into account those efforts, if 

any, being made by any State or foreign 

nation, or any political subdivision of a 

State or foreign nation, to protect such 

species.’’ Here, we describe and 

evaluate those conservation efforts being 

made by the State of Idaho and other 

entities to protect Lepidium 

papilliferum; we also consider 

conservation efforts that are formally 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52049 

planned but have not yet been 

implemented, as per the Service’s Policy 

for the Evaluation of Conservation 

Efforts (68 FR 15100; March 28, 2003). 

These conservation efforts were briefly 

described in our earlier evaluation of 

the threat factors affecting the species. 

Here we present a single summary of the 

conservation efforts implemented or 

planned for the benefit of L. 

papilliferum, which we considered in 

the course of our listing determination. 

Any management actions that were only 

planned at the time of our withdrawal 

of the proposal to list Lepidium 

papilliferum in 2007 (72 FR 1622; 

January 12, 2007) but have since been 

implemented were considered in our 

evaluation of ongoing conservation 

efforts in this rule. 

Ongoing Conservation Efforts 

Currently, there are four formalized 

plans that contain conservation 

measures for Lepidium papilliferum. 

The four plans include: (1) the CCA for 

Slickspot Peppergrass with the State of 

Idaho, BLM, Idaho Army National 

Guard, and nongovernmental 

cooperators (private landowners who 

also hold livestock grazing permits on 

BLM lands) (State of Idaho et al. 2003, 

2006); (2) the Idaho Army National 

Guard Integrated Natural Resource 

Management Plan for Gowen Field/ 

Orchard Training Area (IDARNG 2004); 

(3) the U.S. Air Force Integrated Natural 

Resource Management Plan for the 

Juniper Butte Range (Mountain Home 

Air Force Base) (U.S. Air Force 2004); 

and (4) the Conservation Agreement for 

Slickspot Peppergrass (Lepidium 

papilliferum) at the Boise Airport, Ada 

County, Idaho (Boise Airport 2003). A 

fifth plan that expired in October of 

2006 is a 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 L. 

papilliferum (Hull’s Gulch Agreement) 

(U.S. Fish and Wildlife Service 1996). A 

new agreement is currently being 

crafted to update the expired agreement 

and will include conservation measures 

for portions of four small L. papilliferum 

EOs in the Boise Foothills region on 

lands administered by both the City of 

Boise and Ada County. This new 

agreement is expected to be completed 

by September of 2009. 

The majority of the individual 

conservation efforts being implemented 

for Lepidium papilliferum are contained 

in the State of Idaho CCA, which was 

originally drafted in 2003, and updated 

in 2006; it is scheduled to expire in 

2013. The CCA represents an important 

milestone in the cooperative 

conservation of Lepidium papilliferum 

given its rangewide scope and 

coordinated management across Federal 

and State of Idaho managed lands. The 

CCA includes rangewide efforts that are 

intended to address the need to: 

Maintain and enhance L. papilliferum 

habitat; reduce intensity, frequency, and 

size of natural- and human-caused 

wildfires; minimize loss of habitat 

associated with wildfire-suppression 

activities; reduce the potential for 

invasion of nonnative plant species 

from wildfire; minimize the loss of 

habitat associated with rehabilitation 

and restoration techniques; minimize 

the establishment of invasive nonnative 

species; minimize the degradation or 

loss of habitat from ORV use; mitigate 

the negative effects of military training 

and other associated activities on the 

OTA; and minimize the impact of 

ground disturbances caused by livestock 

penetrating trampling during periods 

when soils are saturated. 

As a signatory of the CCA (State of 

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

primary land management agency 

implementing conservation efforts for 

Lepidium papilliferum on their lands. 

Implementation of the conservation 

measures in the CCA represents a major 

commitment on behalf of the BLM, 

which has management authority for the 

majority of the range where L. 

papilliferum occurs (i.e., 87 percent of 

the total EO area (13,470 ac (5,451 ha)) 

and portions of 69 of the 80 extant EOs). 

Conservation measures for ongoing 

activities from the CCA that were 

appropriate for land-use plan programs 

were included in an August 22, 2006, 

Conservation Agreement between the 

Service and the BLM to avoid or 

minimize impacts to L. papilliferum 

during the BLM’s implementation of 

existing land-use plans. This 

Conservation Agreement between Idaho 

BLM and the Service is scheduled to 

expire on December 31, 2010, at which 

time it may be reviewed for renewal or 

expiration. 

Until recently, the CCA also 

represented an effort by 

nongovernmental cooperators (private 

landowners who also hold BLM 

livestock grazing permits) for the 

conservation of Lepidium papilliferum 

on private lands. Six Memoranda of 

Understanding (MOUs) between 

nongovernmental cooperators and the 

State of Idaho for conservation of L. 

papilliferum on private lands were in 

place from 2004 through December 

2007. We are not aware that these MOUs 

have been reissued at this time. The size 

and habitat condition of L. papilliferum 

locations on these private lands are also 

unknown to the Service. The MOUs 

included 17,045 ac (6,898 ha) of private 

lands; however, less than 2 percent of 

the currently known area occupied by L. 

papilliferum (260 ac (105 ha)) is 

documented as occurring on private 

lands. 

Although a majority of the 

conservation measures identified in the 

CCA have been implemented to date, 

relatively few have been determined at 

this time to be measurably effective for 

conserving Lepidium papilliferum. For 

example, many of the implemented 

measures are conducting surveys, 

monitoring, or providing for public 

outreach and education, which have 

limited direct or long-term conservation 

benefits to the species. With the 

exception of several conservation efforts 

implemented at the OTA that have been 

successful in controlling the effects of 

wildfire on L. papilliferum habitats, 

many of the remaining conservation 

efforts and adaptive management 

provisions identified in the CCA have 

not been implemented over a long 

enough period of time to have sufficient 

certainty they can be effective in 

reducing threats. Furthermore, the 

conservation measures identified in the 

CCA are concentrated on L. papilliferum 

EOs. While this is helpful, the effective 

control of the most significant threats to 

L. papilliferum, wildfire and invasive 

nonnative plant species, requires efforts 

that extend well beyond the boundaries 

of the EOs, since by their nature these 

are expansive threats that occur 

throughout the Great Basin. We 

recognize the conservation efforts 

identified in the CCA as having a 

conservation benefit for L. papilliferum, 

but rangewide their effectiveness in 

reducing or eliminating the most 

significant threats has not been 

demonstrated at this time. 

The IDARNG, another signatory to the 

CCA, also implements conservation 

efforts for Lepidium papilliferum on the 

OTA through its INRMP (IDARNG 2004, 

Chapter 4.4.2). The IDARNG’s OTA 

contains 7,213 ac (2,919 ha) of occupied 

L. papilliferum habitat, 7,163 ac (2,899 

ha) of which represents some of the 

highest-quality occupied L. papilliferum 

habitat in the Snake River Plain region. 

Many of the conservation efforts, such 

as prohibiting military training activities 

within areas reserved for conservation 

of L. papilliferum, have been 

implemented by the IDARNG for more 

than 18 years and have been 

demonstrated to be effective in 

minimizing military training impacts to 

the species. The INRMP for the OTA 

expired in September 2008, and is 

currently being updated (Quinney 2008, 

pers. comm.). 


srobinson on DSKHWCL6B1PROD with RULES4
52050 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

The U.S. Air Force’s INRMP 

completed in 2004 includes 

conservation efforts for Lepidium 

papilliferum. The U.S. Air Force 

manages 2,028 ac (810 ha) of occupied 

L. papilliferum habitat within the 

Juniper Butte Range in the Owyhee 

Plateau region. The INRMP contains 

specific measures developed to 

minimize the impacts from military 

training and the associated indirect 

effects from wildfire, nonnative invasive 

weeds, and livestock use on L. 

papilliferum. For example, the U.S. Air 

Force has a number of ongoing efforts to 

address wildfire suppression on the 

entire 11,500 ac (4,800 ha) Juniper Butte 

Range. The U.S. Air Force addresses 

wildfire prevention through reducing 

standing fuels and weeds, planting fireresistant vegetation in areas with a 

higher potential for ignition sources 

such as along roads, and using wildfire 

indices to determine when to restrict 

military activities when the wildfire 

hazard rating is extreme (U.S. Air Force 

2004, p. 6-55). As a result, the threat 

from wildfire to L. papilliferum 

associated with U.S. Air Force training 

activities is expected to be reduced 

within the Juniper Butte Range. The 

INRMP that includes the Juniper Butte 

Range is scheduled to expire in 2009 

and is currently being updated (EES 

2008). 

A Conservation Agreement between 

the Service and the City of Boise Airport 

was completed in 2003 for the 

conservation of two Lepidium 

papilliferum EOs located on the 

southern portion of Boise Airport lands 

(Boise Airport 2003). Using the latest 

Idaho Natural Heritage Program L. 

papilliferum EO ranks, these two EOs 

include a C-ranked site (2.8 ac (1.2 ha)) 

and a D-ranked site (0.5 ac (0.2 ha)), 

with low documented plant numbers 

and very poor habitat condition (Colket 

et al. 2006, Appendix C). Both EOs 

included in this Conservation 

Agreement are also susceptible to 

impacts from invasive nonnative weeds 

and wildfire. The primary conservation 

actions identified in this agreement 

included the construction of fuel breaks 

around L. papilliferum populations, the 

preclusion of livestock use, minimizing 

the use of herbicides, and signing areas 

to prevent access. We have not received 

documentation of implementation or 

effectiveness of the conservation efforts 

identified in this Conservation 

Agreement. This agreement is scheduled 

to expire in December 2015. We 

acknowledge the positive conservation 

intent of this agreement, and although 

the status of the efforts are unknown, 

even if they were known to be 

implemented and effective, the area 

covered by the City of Boise 

Conservation Agreement is so small that 

it would have little effect on our 

ultimate finding in this rule. 

Planned Conservation Efforts 

Prior to our 2007 withdrawal notice 

(72 FR 1622; January 12, 2007), we 

reviewed the available information for 

all of the individual conservation efforts 

contained in five conservation plans 

developed for Lepidium papilliferum 

(State of Idaho CCA, IDARNG INRMP, 

U.S. Air Force INRMP, Boise Airport 

CA, and Hull’s Gulch Agreement) to 

evaluate how many were implemented 

or certain to be implemented in the 

future; and how many efforts were so 

effective as to have contributed to the 

elimination or reduction of one or more 

threats to the species. Based upon our 

review at that time, we determined that 

373 of the nearly 600 individual 

conservation efforts identified in the 5 

plans were currently implemented and 

that 35 of these efforts were determined 

to be both certain to be implemented 

and effective in reducing threats to L. 

papilliferum or were already known to 

be implemented and effective in 

reducing threats to the species. Since 

that time, we have received additional 

information from the implementing 

agencies that describe the status of at 

least 152 conservation measures 

included in 3 of the 5 conservation 

plans (State of Idaho CCA, IDARNG 

INRMP, and US Air Force INRMP) that 

were implemented in 2007 and 2008 

(CH2MHill 2007a, p. 16; CH2MHill 

2007b, pp. 1-6; Quinney 2007 pp.1-3; 

USBLM 2007, p. 2-4; CH2MHill 2008a, 

p. 17; CH2MHill 2008b, pp. 1-6; 

Quinney 2008 pp.1-3; USBLM 2008a, 

pp. 2-38; USBLM 2008c, pp. 1-15; 

Colket 2009, pp. 65-72). We have not 

received specific information regarding 

conservation measures contained in the 

Boise Airport conservation agreement 

that have been implemented, or how 

effective these measures have been in 

reducing threats to L. papilliferum for 

2007 or 2008. The fifth conservation 

plan, the Hull’s Gulch Agreement 

between Boise City and the Service, 

expired in October 2006 and has yet to 

be renewed. 

Our latest evaluation of planned 

future conservation efforts, taking into 

consideration the most recent 

information provided by the 

implementing agencies, again concludes 

that 35 out of roughly 600 individual 

management actions identified in the 5 

formalized conservation plans for 

Lepidium papilliferum are certain to be 

implemented and effective. However, 

these 35 conservation efforts determined 

to be implemented and effective are 

from the CCA, Air Force INRMP and 

OTA INRMP, and are not applicable 

rangewide. For example, 20 of the 35 

conservation efforts are primarily 

directed at conserving L. papilliferum at 

1 of 3 EOs located on the OTA. 

Therefore, these 35 measures would not 

prevent the species from becoming 

endangered in the foreseeable future 

either rangewide or on a significant 

portion of the species’ range. We thus 

do not consider these 35 actions 

sufficient to offset the threats posed to 

L. papilliferum across its range by the 

modified wildfire regime; invasive 

nonnative plants; development; 

potential seed predation by harvester 

ants; and habitat fragmentation and 

isolation, to the point that we would 

consider it unlikely that L. papilliferum 

will become endangered within the 

foreseeable future. 

Summary of Ongoing and Planned 

Conservation Efforts 

We recognize the long list of ongoing 

and proposed conservation efforts by 

the State of Idaho, IDARNG, U.S. Air 

Force, and other non-governmental 

cooperators being put forth to conserve 

Lepidium papilliferum. All parties 

should be commended for their 

conservation efforts. Our review of 

conservation efforts indicates that not 

all of the measures identified in the 

conservation plans have been 

implemented and most have not been 

demonstrated at this time to effectively 

reduce or eliminate the most significant 

threats to the species. Many of these 

conservation efforts are limited in their 

ability to effectively reduce the longterm habitat degradation and 

destruction occurring within the 

sagebrush-steppe ecosystem and L. 

papilliferum habitats across the range of 

the species from the effects of a changed 

wildfire regime and nonnative plant 

invasions, in addition to other threats. 

In many cases, effective control 

measures for these threats are not yet 

known, financially or technically 

feasible, or logistically possible to 

implement on the scale that would be 

necessary to successfully ameliorate the 

threat throughout the range of L. 

papilliferum. Although the ongoing 

conservation efforts demonstrated to be 

effective are a positive step toward the 

conservation of L. papilliferum, and a 

few, such as those designed to reduce 

the impact of ground disturbances 

caused by livestock when soils are 

saturated in the spring, described under 

Livestock Use, above, have likely 

reduced the severity of some threats to 

the species, on the whole we find that 

the conservation efforts in place at this 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52051 

time are not sufficient to offset the 

degree of threat posed to the species by 

the modified wildfire regime; invasive 

nonnative plants; development; 

potential seed predation by harvester 

ants; and habitat fragmentation and 

isolation, to the point that we would 

consider it unlikely that L. papilliferum 

will become endangered within the 

foreseeable future. 

We have also considered all formally 

planned conservation efforts, by 

evaluating the individual conservation 

efforts contained in five conservation 

plans developed for Lepidium 

papilliferum to evaluate how many were 

implemented or certain to be 

implemented in the future; and how 

many efforts were so effective as to have 

contributed to the elimination or 

reduction of one or more threats to the 

species. We have no information 

indicating that there are any new 

conservation efforts planned for the 

future that we have not already 

evaluated in the course of applying our 

Policy for the Evaluation of 

Conservation Efforts (68 FR 15100; 

March 28, 2003) to management actions 

planned for the benefit of L. 

papilliferum, as described in past 

actions for this species (69 FR 3094; 72 

FR 1622). We recognize the benefit of 

these planned conservation measures 

and acknowledge the efforts of the 

entities engaged in planning these 

measures for the benefit of L. 

papilliferum. However, as with ongoing 

conservation efforts, in most cases the 

measures are simply not logistically 

feasible for implementation at the scale 

that would be required to effectively 

reduce the threats to the species across 

its range. Based on our most recent 

evaluation, we conclude that those 

planned conservations efforts that we 

consider likely to be implemented and 

effective are not sufficient to offset the 

threats posed to L. papilliferum by the 

modified wildfire regime; invasive 

nonnative plants; development; 

potential seed predation by harvester 

ants; and habitat fragmentation and 

isolation, to the point that we would 

consider it unlikely that L. papilliferum 

will become endangered within the 

foreseeable future. 

In summary, all ongoing conservation 

efforts have been considered and 

evaluated in terms of their effectiveness 

in ameliorating the threats to Lepidium 

papilliferum as described in this rule. 

We have additionally considered all 

formally planned future conservation 

efforts for the species, and evaluated 

those efforts in terms of the certainty of 

their implementation and their potential 

for effectiveness in ameliorating the 

threats to L. papilliferum. We recognize 

and acknowledge the efforts of the many 

entities participating in conservation 

efforts for the protection of L. 

papilliferum. However, our evaluation 

of the ongoing and planned 

conservation efforts for the species 

concludes that these efforts are not 

sufficient to offset the threats described 

in this rule to the point that we consider 

it unlikely that L. papilliferum will 

become endangered within the 

foreseeable future. 

Finding 

We have carefully assessed the best 

scientific and commercial information 

available regarding the present and 

future threats to Lepidium papilliferum. 

This plant is endemic to southwest 

Idaho and occurs within a limited 

geographical range that totals 

approximately 16,000 ac (6,475 ha). The 

species predominantly occurs in highly 

specialized and unique microsite 

habitats called slickspots within the 

sagebrush-steppe ecosystem. The 

specialized slickspot habitats were 

formed during the Pleistocene period 

and are considered a finite resource; the 

fact that these slickspots likely cannot 

be recreated or restored once they have 

been lost was an important 

consideration in our evaluation of the 

threats to L. papilliferum. In addition, 

the species’ limited geographical range 

makes it particularly vulnerable to the 

many threats affecting its habitat. We 

have evidence indicating that the finite 

slickspot habitats of the species are 

continuing to degrade in quality from a 

variety of threats. Based on the best 

scientific data currently available, the 

primary significant threats to the species 

are the effects of wildfire and invasive 

nonnative plants, especially Bromus 

tectorum. 

In our 2007 finding (72 FR 1622; 

January 12, 2007), we concluded: ‘‘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 now have new information 

indicating a statistically significant 

negative association between L. 

papilliferum abundance and wildfire, 

and between L. papilliferum abundance 

and cover of B. tectorum in the 

surrounding plant community; these 

negative associations are consistent 

throughout the range of the species. 

Wildfire occurs throughout the range of 

L. papilliferum and has dramatically 

increased in both frequency and extent 

over historical levels, especially where 

B. tectorum is dominant. We expect this 

trend to continue and possibly increase 

due to the projected effects of climate 

change. Furthermore, as B. tectorum and 

other nonnative annual grasses continue 

to spread and degrade the sagebrushsteppe ecosystem, we expect continued 

increases in fire frequency and 

magnitude, with associated negative 

impacts on L. papilliferum. 

As wildfire continues to promote the 

conversion of sagebrush to nonnative 

annual grasslands, we also anticipate 

that Owyhee harvester ants will expand 

into areas occupied by L. papilliferum, 

as the density of harvester ants is 

negatively associated with sagebrush 

cover, and they appear to readily 

colonize grassland habitats that are 

replacing sagebrush. Seed predation on 

L. papilliferum is thus expected to 

increase, with negative consequences 

for plant reproduction and the 

maintenance of the persistent seed bank. 

Additionally, future development 

threatens many of the remaining L. 

papilliferum occupied sites, primarily 

in the Snake River Plain and Boise 

Foothills. Development can result in the 

permanent loss of slickspot microsite 

habitats, and contributes to the 

problems associated with habitat 

fragmentation and the isolation of small 

populations. The loss of slickspots, 

particularly those slickspots occupied 

by the species and thus clearly 

providing the requisite conditions to 

support L. papilliferum, is of great 

concern due to the finite nature of this 

resource. Habitat fragmentation and 

isolation potentially reduces the longterm viability of populations by 

impeding genetic exchange through 

insect pollination or pollen dispersal, 

resulting in decreased seed production 

and possibly reduced genetic diversity. 

As with the 2007 finding (72 FR 1622; 

January 12, 2007), we do not see strong 

evidence of a steep negative population 

trend for the species. However, recent 

analysis of the best available scientific 

data suggests that Lepidium 

papilliferum numbers may be trending 

downward, and the dataset from the 

rough census areas on the OTA, which 

we consider to be the most reliable, 

shows a statistically significant 

downward trend in density over the last 

18 years. The evidence suggests this 

negative trend is independent of any 

trend in precipitation over the same 

period of time. The extreme variability 

in annual abundance makes the 

detection of any such trend statistically 

challenging; not all monitoring data 

have shown consistently significant 

results, and, as described earlier, there 

are numerous factors that serve to 

complicate the confident detection of a 

population trend in this species. We do 

now have evidence, however, that the 

primary threats of wildfire and invasive 


srobinson on DSKHWCL6B1PROD with RULES4
52052 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

nonnative plants, especially B. 

tectorum, are currently acting on the 

species and its habitat throughout its 

limited range, and furthermore we now 

have evidence of a significant negative 

association between the abundance of L. 

papilliferum and these two threats. 

Indications are that all of the significant 

threats to L. papilliferum identified in 

this rule, including development and 

habitat fragmentation, but especially 

wildfire and invasive nonnative plants, 

will continue and likely increase into 

the foreseeable future. The projected 

future consequences of climate change, 

if realized, will further magnify the 

primary threats posed by wildfire and B. 

tectorum. Furthermore, we conclude 

from our evaluation of the ongoing and 

planned conservation efforts for 

Lepidium papilliferum that, despite the 

best efforts of the State and other 

management agencies, there is no 

information leading us to believe that 

sufficient management tools are 

currently being implemented that are 

capable of effectively reducing or 

ameliorating the primary threats of 

wildfire and invasive nonnative plants, 

particularly B. tectorum, across the 

range of L. papilliferum, to a point 

where the species is not likely to 

become endangered in the foreseeable 

future. As we can reasonably anticipate 

the continuation or increase of all of the 

significant threats to L. papilliferum into 

the foreseeable future, even after 

accounting for ongoing and planned 

conservation efforts, and based on the 

observed significant negative correlation 

between the primary threats of wildfire 

and invasive nonnative plants, 

particularly B. tectorum, and the 

abundance of L. papilliferum, we can 

reasonably infer that the negative 

consequences of these threats on the 

species will continue, and, under 

current conditions, population declines 

will likely be observed within the 

foreseeable future to the point at which 

L. papilliferum will become an 

endangered species. 

Section 3 of the Act defines an 

endangered species as ‘‘any species 

which is in danger of extinction 

throughout all or a significant portion of 

its range’’ and a threatened species as 

‘‘any species which is likely to become 

an endangered species within the 

foreseeable future throughout all or a 

significant portion of its range.’’ 

Lepidium papilliferum is currently 

affected by a variety of threats across its 

entire geographic range. As we have not 

yet observed the extirpation of local 

populations or steep declines in the 

abundance of the species, we do not 

believe the status of the species is such 

that it is presently in danger of 

extinction. Therefore, we do not believe 

L. papilliferum meets the definition of 

an endangered species. We additionally 

considered whether any significant 

portion of the species’ range meets the 

definition of endangered (see 

Significant Portion of the Range 

Evaluation, below); however, we could 

not determine that any significant 

portion of the species’ range is presently 

in danger of extinction, thus no 

significant portion of the species range 

warrants listing as endangered. We can, 

however, reasonably anticipate the 

impacts of the threats on L. papilliferum 

rangewide, and we believe those threats 

acting in combination are likely to result 

in the species becoming endangered 

within the foreseeable future. Therefore, 

we are listing L. papilliferum as a 

threatened species throughout all of its 

range under the Act. 

Significant Portion of the Range (SPR) 

Evaluation 

Section 3 of the Act defines an 

endangered species as a species in 

danger of extinction throughout all or a 

significant portion of its range, and a 

threatened species as a species that is 

likely to become an endangered species 

within the foreseeable future throughout 

all or a significant portion of its range. 

In our analysis for this final rule, we 

initially evaluated the status of and 

threats to the species throughout its 

entire range. Lepidium papilliferum is 

restricted to a relatively small range in 

southwestern Idaho. The range of the 

species has been divided into three 

physiographic regions, based on 

differences in topography, soil, and 

relative abundance of L. papilliferum. 

These three physiographic regions, 

shown in Figure 1, are the Boise 

Foothills, Snake River Plain, and 

Owyhee Plateau. In our evaluation of 

threats to L. papilliferum, we 

determined that the threats acting on the 

species may differ in severity to some 

degree between these physiographic 

regions, as demonstrated by Sullivan 

and Nations (2009, Chapter 8, pp. 97- 

138). On the basis of this evaluation, we 

determined that the entire species meets 

the definition of threatened under the 

Act due to the loss or degradation of its 

habitat, due primarily to the modified 

wildfire regime and invasive nonnative 

plant species. The basis of this 

determination is captured within the 

analysis of each of the five listing 

factors, and the Finding immediately 

preceding this section. 

Recognizing the potential differences 

in the magnitude of threats, we 

evaluated whether there were any 

specific areas or populations that may 

be disproportionately threatened such 

that they currently meet the definition 

of an endangered species versus a 

threatened species. Our evaluation of 

whether there are any significant 

portions of Lepidium papilliferum’s 

range (SPR) where listing the species as 

endangered may be warranted follows. 

On March 16, 2007, a formal opinion 

was issued by the Solicitor of the 

Department of the Interior, ‘‘The 

Meaning of ‘In Danger of Extinction 

Throughout All or a Significant Portion 

of Its Range’’’ (USDI 2007). We have 

summarized our interpretation of that 

opinion and the underlying statutory 

language below. 

In determining whether a species is 

threatened or endangered in a 

significant portion of its range, we first 

identify any portions of the range of the 

species that warrant further 

consideration. The range of a species 

can theoretically be divided into 

portions in an infinite number of ways. 

However, there is no purpose to 

analyzing portions of the range that are 

not reasonably likely to be significant 

and threatened or endangered. To 

identify those portions that warrant 

further consideration, we determine 

whether there is substantial information 

indicating that (i) the portions may be 

significant and (ii) the species may be in 

danger of extinction there or likely to 

become so within the foreseeable future. 

In practice, a key part of this analysis is 

whether the threats are geographically 

concentrated in some way. If the threats 

to the species are essentially uniform 

throughout its range, no portion is likely 

to warrant further consideration. 

Moreover, if any concentration of 

threats applies only to portions of the 

range that are unimportant to the 

conservation of the species, such 

portions will not warrant further 

consideration. 

If we identify any portions that 

warrant further consideration, we then 

determine whether in fact the species is 

threatened or endangered in any 

significant portion of its range. 

Depending on the biology of the species, 

its range, and the threats it faces, it may 

be more efficient for the Service to 

address the significance question first, 

or the status question first. Thus, if the 

Service determines that a portion of the 

range is not significant, the Service need 

not determine whether the species is 

threatened or endangered there. 

Alternatively, if the Service determines 

that the species is not threatened or 

endangered in a portion of its range, the 

Service need not determine if that 

portion is significant. If the Service 

determines that both a portion of the 

range of a species is significant and the 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52053 

species is threatened or endangered 

there, the Service will specify that 

portion of the range as threatened or 

endangered pursuant to section 4(c)(1) 

of the Act. 

To determine whether any portions of 

the range of Lepidium papilliferum 

warrant further consideration as 

possible endangered significant portions 

of the range, we reviewed the entire 

supporting record for this final listing 

determination with respect to the 

geographic concentration of threats and 

the significance of portions of the range 

to the conservation of the species. In 

this case, we first evaluated whether 

substantial information indicated (i) the 

threats are so concentrated in any 

portion of the species’ range that the 

species may be currently in danger of 

extinction in that portion; and (ii) if so, 

whether those portions may be 

significant to the conservation of the 

species. 

Our rangewide review of the species 

concluded that Lepidium papilliferum is 

likely to become endangered within the 

foreseeable future. Therefore, the 

species meets the definition of 

threatened under the Act. As described 

above, to establish whether any areas 

may warrant further consideration, we 

reviewed our analysis of the five listing 

factors to determine whether any of the 

significant threats identified were so 

concentrated that some portion of L. 

papilliferum’s range may currently be in 

danger of extinction. All of the 

significant threats identified in this rule, 

the primary threats of modified wildfire 

regime and invasive nonnative plant 

species, and the lesser threats of 

development and habitat fragmentation 

and isolation, act on the species 

throughout its range. The threat of 

development is somewhat greater in the 

Boise Foothills and Snake River Plain 

physiographic regions relative to the 

Owyhee Plateau, but as discussed in our 

analysis under Factor A, we have no 

information indicating that this threat is 

so imminent or disproportionately 

severe as to place the species in danger 

of extinction within those 

physiographic regions at present. In 

addition, the analysis of Sullivan and 

Nations (2009) demonstrated that the 

magnitude of the threats to L. 

papilliferum from some factors, such as 

individual species of invasive nonnative 

plants (e.g., Agropyron cristatum) may 

vary to some degree between 

physiographic regions. However, based 

on our review of the record, we did not 

find substantial information indicating 

that any of the significant threats to the 

species were so severe or so 

concentrated as to indicate that some 

portions of L. papilliferum’s range 

qualify as endangered. As described in 

our Finding above, the threats are such 

that we anticipate L. papilliferum will 

become endangered within the 

foreseeable future across its range. 

However, at present we have no 

evidence of any recent localized 

population extirpations, nor is there 

evidence of any localized precipitous 

population declines indicating that L. 

papilliferum is currently in danger of 

extinction in any portion of its range. As 

a result, while the best scientific data 

available allows us to make a 

determination as to the rangewide status 

of L. papilliferum, we have determined 

that the best available data show that 

there are no portions of the range in 

which the threats are so concentrated as 

to place the species currently in danger 

of extinction. Because we find that L. 

papilliferum is not endangered in any 

portion of its range, we need not address 

the question of whether any portion 

may be significant. 

Peer review 

In accordance with our peer review 

policy published on July 1, 1994 (59 FR 

4270), and current Department of the 

Interior guidance, we solicited seven 

individuals with scientific expertise on 

Lepidium papilliferum, its habitat, and 

the geographic region in which the 

species occurs to provide their expert 

opinion and to review and interpret 

available information on the species’ 

status and threats. Four of the seven 

peer reviewers had previously 

participated on a May 2006 expert panel 

of independent scientists convened to 

evaluate the available data and threats 

to L. papilliferum as part of our 2007 

listing determination. Although all 

seven of the original expert panelists 

were invited to participate in the 

current evaluation, not all were 

available to do so. The peer reviewers 

were asked for their expert opinion on 

the best available information by 

responding to a series of questions 

posed by the Service regarding L. 

papilliferum population trends, threat 

factors, and their effects on L. 

papilliferum population viability. We 

received responses and comments from 

six of the seven peer reviewers, which 

are provided in the following summary 

and incorporated into the final rule as 

appropriate. 

Peer Review Comments and Responses 

Population Trend 

(1) Comment: The peer reviewers 

differed in their explanation for 

describing a population trend for 

Lepidium papilliferum. One peer 

reviewer stated they have ‘‘no 

confidence in any trend data due to 

small sample size and lack of 

independence between years,’’ and 

asserted that there are no data to 

indicate that the population is in 

decline. Two peer reviewers agreed that 

the available information revealed a 

significant declining trend that was not 

strong for the years analyzed, but 

expressed a lack of confidence that this 

trend could be reliably projected into 

the future. Another peer reviewer did 

not see strong evidence for a declining 

population and believed that viable 

populations would be maintained over 

the next 50 years if current conservation 

efforts continue. One peer reviewer 

offered that ‘‘ultimately, the availability 

and quality of suitable habitat, not past 

population trends, will determine L. 

papilliferum’s population trajectory.’’ 

Our Response: In our 2007 

withdrawal of the proposed rule to list 

Lepidium papilliferum as endangered 

(72 FR 1622; January 12, 2007), we 

stated that data on overall population 

trends for L. papilliferum were 

inconsistent. Since that time we have 

received and evaluated new 

information, including independent 

statistical analyses of long-term plant 

monitoring data, in an attempt to 

discern any long-term trend in the 

abundance of the species. We 

acknowledge that forming a reliable 

estimate of trend in the abundance of L. 

papilliferum over time is complicated 

by multiple factors; however, we are 

mandated by the Act to use the best 

available scientific and commercial data 

in our assessment. Therefore, we have 

relied upon that data we have 

determined to be most reliable for the 

discernment of population trend. As 

described above in the section 

Population Abundance and Trend, one 

complicating factor is that individual 

plants may act as either an annual or a 

biennial form in any given year, and 

there can be varying numbers of plants 

acting as either spring-flowering 

annuals or overwintering rosettes. The 

relative proportions of these two lifehistory forms can fluctuate annually 

depending on a variety of factors, 

including precipitation, temperature, 

and the abundance of rosettes produced 

the previous year (Unnasch 2008, pp. 

14-15; Sullivan and Nations 2009, pp. 

43-44, 134-135). Another factor is that L. 

papilliferum has a seed bank with a 

longevity of approximately 12 years, 

likely as an adaptation to a highly 

variable environment. Years of good 

rainfall favorable for germination and 

survival may be followed by periods of 

drought; a persistent seed bank provides 

a population buffer against years of poor 


srobinson on DSKHWCL6B1PROD with RULES4
52054 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

reproductive performance in a highly 

variable environment (Meyer et al. 2005, 

p. 21). The tendency of only a small 

percentage of a single year’s seed cohort 

to germinate in any given year over a 

12–year period results in a significant 

lag effect in detecting any real 

underlying change in total population 

abundance over the long term. 

Further complications are posed by 

the extreme annual variability observed 

in plant numbers. This challenge was 

recognized by Mancuso and Moseley 

(1998, p. 1), who noted the difficulty in 

discerning any real trend in population 

abundance of above-ground individuals 

of Lepidium papilliferum, since in many 

years the majority of the population is 

represented by the seed bank, hence 

sites that ‘‘have thousands of 

individuals one year may have none the 

next year.’’ Some of the variability in 

yearly plant numbers is likely due to the 

relationship between L. papilliferum 

and precipitation. The annual 

abundance or density of L. papilliferum 

plants shows a significant positive 

association with the levels of spring 

rainfall, roughly from March through 

May (Meyer et al. 2005, p. 15; Palazzo 

et al. 2005, p. 9; Sullivan and Nations 

2009, pp. 39-41), and the survival of 

biennials is associated with increased 

summer rainfall (Meyer et al. 2005, p. 

15). In addition, temperature appears to 

play a role in annual abundance of L. 

papilliferum in concert with 

precipitation, although the exact nature 

of that relationship is complex and not 

well understood (Sullivan and Nations 

2009, p. 57). 

We contracted with independent 

consultants to analyze the available 

population data for Lepidium 

papilliferum, to assist us in determining 

which datasets represent the best 

available information and to provide an 

independent assessment of any 

population trend in the species, if 

possible. The resulting report, cited in 

this document as Sullivan and Nations 

2009, was prepared to evaluate 

monitoring and survey methodologies 

and conduct statistical analyses on 

Lepidium papilliferum data collected on 

the OTA since 1990, as well as to 

analyze the rangewide Habitat Integrity 

and Population (HIP) monitoring data 

collected over the past 5 years (see our 

response to the State of Idaho 

Comments, below, for more information 

on the Sullivan and Nations 2009 

report). This report was made available 

to the peer reviewers. The evaluation of 

Sullivan and Nations was based on a 

simple model of L. papilliferum 

abundance or density as a linear 

function of time, intended only to 

discern whether there was any general 

trend in the population; the authors 

acknowledge that the dynamics are 

complicated, and note that their model 

is not intended to describe (nor explain) 

the details of the temporal pattern of 

abundance or density of L. papilliferum 

(Sullivan and Nations 2009, p. 38). The 

authors concluded that the population 

data from the rough census monitoring 

on the OTA represents the most reliable 

dataset for the species, and that there is 

‘‘limited evidence for declining 

populations,’’ in that trends on the OTA 

are negative but only statistically 

significant for the rough census areas 

(Sullivan and Nations 2009, pp. 2, 44). 

The extreme variability in annual 

counts of the species makes it difficult 

to discern a trend in numbers with 

statistical confidence; for this reason for 

the purposes of modeling a trend 

through time, we place greater 

confidence in the longest time series of 

monitoring data available, which is from 

the OTA (up to 18 years of data for some 

rough census areas and all special-use 

plots). This is in agreement with the 

independent assessment of Sullivan and 

Nations (2009, pp. 3, 36, 93). In 

addition, those authors had slightly 

greater confidence in the data from the 

rough census areas on the OTA, since 

they are larger than the special-use plots 

and have multiple slickspots; therefore, 

the counts are less susceptible to 

localized impacts (Sullivan and Nations 

2009, p. 55). 

Because the OTA data on Lepidium 

papilliferum abundance and density 

results from a standardized collection 

effort over a period of nearly 20 years, 

we consider the information from the 

OTA to be the best available data with 

which to detect any general long-term 

population trend for L. papilliferum. 

The analysis of this dataset from the 

rough census areas on the OTA shows 

a statistically significant downward 

trend in density of L. papilliferum over 

the last 18 years. This trend appears to 

be independent of any trend in 

precipitation over the same time period, 

indicating this decline is occurring due 

to factors other than precipitation 

pattern (Zwartjes 2009, p. 1). We 

therefore conclude that the best 

available data suggest that Lepidium 

papilliferum numbers are probably 

trending downward. Furthermore, since 

this significant downward trend has 

been detected on the OTA, which 

represents some of the highest quality 

habitat remaining for L. papilliferum, 

we believe it is reasonable to infer that 

this negative trend is similar or possibly 

even greater rangewide, in areas of 

lower quality habitat. 

We note that one peer reviewer 

questioned whether a decline in 

Lepidium papilliferum abundance is 

really occurring, based on high numbers 

of plants recorded in 2008. Another peer 

reviewer, however, had little confidence 

that this one-time observation was 

indicative of any long-term increasing 

trend. We note that the increase in 

numbers of L. papilliferum in 2008 is 

largely based on substantial increases at 

only 6 out of 80 HIP transects; 66 

percent of all L. papilliferum counted in 

2008 were found at these 6 transects 

(Colket 2009, p. 26). Furthermore, the 

plant community where these six 

transects are located has not been 

burned, and is dominated by native 

sagebrush (Artemisia tridentata). These 

six transects therefore represent some of 

the highest-quality habitat remaining for 

L. papilliferum. Since the increases 

observed in 2008 were highly localized 

and occurred in remnant high-quality 

habitats, and considering that rangewide 

most L. papilliferum occurrences are in 

degraded habitats and counts tend to be 

highly variable from year to year, we do 

not believe it is reasonable to infer that 

this one-time increase in abundance 

portends any future rangewide increases 

in abundance of the species. Please also 

see ‘‘2008 HIP Survey Results’’ under 

our response to public comments 

number 12, below. 

Data Quality 

(2) Comment: One peer reviewer 

stated that information contained in 

many of the study reports is based on 

data that were not collected for specific 

analysis, but instead represents an 

analysis that was performed on data 

whose accuracy is unknown or from 

small data sets comprised of 

interdependent data. Another peer 

reviewer noted the difficulty in 

comparing different data sets as well as 

data sets with differing collection 

methodologies; while another reviewer 

identified that several of the data sets 

examined were collected over such 

short periods (2 to 3 years) that the 

study results were of limited value. In 

contrast, another peer reviewer stated 

that it is important to make conclusions 

based on available information when 

unequivocal data is lacking. 

Our Response: The Act requires us to 

make listing decisions based solely on 

the best scientific and commercial 

information available at the time the 

decision is being made (section 

4(b)(1)(A)). We thoroughly reviewed and 

evaluated all available scientific and 

commercial data for Lepidium 

papilliferum in preparing this final 

listing determination. We reviewed 

historical and recent publications, as 

well as unpublished reports concerning 

L. papilliferum and sagebrush-steppe 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52055 

habitats of southwestern Idaho. As part 

of our process, the seven peer reviewers 

were asked to provide a critical 

examination of the new scientific 

information pertaining to L. 

papilliferum. This information included 

both long-term and recent HII/HIP 

rangewide survey and monitoring data, 

the statistical analyses of long-term OTA 

monitoring data, and the 5 years of 

available HIP monitoring data 

completed by an independent 

consultant. In addition, we received an 

independent critique of the 

methodologies of several recent reports 

or analyses of L. papilliferum data 

(Sullivan and Nations 2009, pp. 139- 

148), to assist in our assessment of the 

best available data. 

We agree that the differing 

methodologies and lack of 

standardization present challenges in 

evaluating the data relevant to Lepidium 

papilliferum. Furthermore, much of the 

data are observational in nature; that is, 

the data were not collected based on 

controlled experiments, but are 

primarily based on observations of the 

relative conditions or abundance of 

various environmental variables, such 

as livestock print cover and the relative 

abundance of L. papilliferum. However, 

as noted above, we have a legal 

obligation under the Act to make a 

determination based upon the best 

scientific and commercial data available 

at the time; the statute does not provide 

for additional research, nor does it 

provide the option of not making a 

determination. We must therefore 

evaluate all of the scientific and 

commercial data before us to determine 

which data we consider to be the best 

available. As part of our evaluation, we 

carefully considered factors such as the 

time series of data collection, the 

variability of the data, and 

standardization of data-collection 

procedures in weighing the relative 

value or reliability of study results. We 

considered all of these factors in 

considering the relative quality of the 

data available, and in determining 

which data to rely upon in our 

determination. Throughout our review 

and evaluation, we followed the 

Service’s Information Quality 

Guidelines (USFWS 2007) to prepare 

this final determination. 

Threats to the Species 

(3) Comment: The peer reviewers 

varied in describing which threats they 

considered to be of primary importance 

to the population viability of Lepidium 

papilliferum. Three of the six peer 

reviewers expressed concern regarding 

the impact of wildfire on L. papilliferum 

and its habitat, while four of six peer 

reviewers mentioned habitat 

degradation and loss of the sagebrushsteppe habitat from exotic and invasive 

nonnative grasses to be of concern or a 

primary threat. Other threats identified 

included development (two reviewers), 

seed predation by harvester ants (two 

reviewers), and habitat fragmentation 

(two reviewers). One reviewer identified 

livestock as a potential threat, one 

reviewer asserted that there are no good 

data to suggest that livestock are a 

threat, and one reviewer suggested that, 

if managed appropriately, livestock 

could be utilized to manage the threat 

of nonnative invasive grasses and the 

associated increase in fire frequency. 

One peer reviewer stated that there are 

few reliable scientific studies to show 

any cause-and-effect relationships to L. 

papilliferum, and stated that the species 

continues to exist in areas of supposed 

threats, including ‘‘burned over areas.’’ 

Our Response: In making this 

determination, we evaluated several 

potential threat factors including the 

effects of wildfire; invasive nonnative 

plants; development; seed predation; 

livestock use; wildfire management; 

habitat fragmentation and small 

populations; military training; 

recreation; and climate change. Of all 

the threat factors examined, we 

determined that the modified wildfire 

regime affecting the species’ sagebrushsteppe habitat in combination with the 

spread of nonnative invasive annual 

plants such as Bromus tectorum and 

Taeniatherum caput-medusae are likely 

the primary factors affecting abundance 

and the long-term persistence of 

Lepidium papilliferum. Tightly 

controlled experiments that demonstrate 

clear causal relationships between 

variables examined are rare. Studies that 

demonstrate a significant or nonsignificant correlation between variables 

are prevalent in the scientific literature, 

and in many cases, depending on factors 

such as the quality of the data and 

analysis, constitute the best information 

available. For example, such analyses 

have demonstrated a significant 

negative relationship between the 

density or abundance of L. papilliferum 

and the occurrence of fire and cover of 

B. tectorum (Sullivan and Nations 2009, 

pp. 116-118, 130-131, 135-137). Based 

on this observed significant 

relationship, we infer that as the 

occurrence of fire and the cover of B. 

tectorum increase, we will observe a 

decrease in the density or abundance of 

L. papilliferum. A complete review and 

evaluation of the threats affecting L. 

papilliferum, including a discussion of 

our rationale in assessing those threats, 

is presented in the Summary of Factors 

Affecting the Species section of this 

rule. 

(4) Comment: The peer reviewers 

varied in their estimates of a time period 

over which they could reliably predict 

the effects of threats, both individually 

and synergistically, on the population 

viability and survival of Lepidium 

papilliferum. One peer reviewer could 

not ‘‘reliably predict the effect of each 

of the primary threats to the species, 

based on the data before me since the 

data does not exist.’’ Another peer 

reviewer suggested that given current 

trends in habitat loss and degradation, 

Lepidium papilliferum ‘‘is likely at a 

tipping point in terms of its prospect for 

survival,’’ and doubted that the species 

would persist in sustainable numbers 

beyond the next 50 to 75 years. Most 

peer reviewers did not project a time 

period for predicting threat effects or 

extinction risk, stating that future 

projections were likely speculative. 

Our Response: As described above, 

the Act requires us to make listing 

decisions based solely on the best 

scientific and commercial data available 

at the time the decision is being made 

(section 4(b)(1)(A)). Based upon the best 

scientific and commercial data 

available, we must make a 

determination as to whether the species 

under consideration is in danger of 

extinction throughout all or a significant 

portion of its range (endangered), or if 

the species is likely to become 

endangered within the foreseeable 

future throughout all or a significant 

portion of its range (threatened). We 

consider the ‘‘foreseeable future’’ to be 

that period of time over which events 

can reasonably be anticipated. In 

considering threats to the species and 

whether they rise to the level such that 

listing the species as threatened or 

endangered is warranted, we assess 

factors such as the imminence of the 

threat (is it currently impacting the 

species, and is it reasonable to expect 

the threat to continue into the future?), 

the scope or extent of the threat, the 

severity of the threat, and the synergistic 

effects of all threats combined. If we 

determine that the species is not 

currently in danger of extinction, then 

we must determine whether, based 

upon the nature of the threats, it is 

reasonable to anticipate that the species 

may become in danger of extinction 

within the foreseeable future. 

We have identified the present or 

threatened destruction, modification, or 

curtailment of Lepidium papilliferum’s 

habitat or range as a threat to the 

species, based on the observed negative 

association between the abundance or 

density of the plant and the current, 

frequent fire regime and invasion of 


srobinson on DSKHWCL6B1PROD with RULES4
52056 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

Bromus tectorum and other nonnative 

plants, as well as the direct loss of 

limited slickspot microsite habitats to 

development. Predation is an additional 

threat to the persistence of the species, 

as seed predation by harvester ants has 

potentially significant consequences for 

the plant’s seed bank, and the presence 

of harvester ants appears to be 

associated with the observed conversion 

of sagebrush-steppe to nonnative annual 

grasslands. Habitat fragmentation and 

isolation resulting from development 

and associated infrastructure, such as 

utility lines, contributes to the threats of 

wildfire and nonnative plant invasion, 

and may additionally impact L. 

papilliferum by limiting genetic 

exchange between populations via 

insect pollination. Climate change may 

further accelerate the conversion of 

intact sagebrush-steppe habitat to 

invasive nonnative annual grasslands, 

with subsequent associated increases in 

wildfire frequency and, potentially, 

harvester ant expansion. These threats 

are all occurring at present, and based 

on the evidence before us, we believe it 

is reasonable to anticipate that the 

current regime of frequently recurring 

wildfires, the invasion of nonnative 

grasses and other plants, development, 

and the expansion of harvester ants will 

continue and likely increase into the 

foreseeable future. Although 

conservation measures to address some 

of these threats have been considered 

and in some cases implemented, 

effective controls throughout the range 

of the L. papilliferum are simply not 

available in many cases. For example, it 

is not anticipated that landscapes 

dominated by B. tectorum can feasibly 

be restored to intact sagebrush-steppe 

habitat within the foreseeable future, as 

restoration of L. papilliferum’s native 

sagebrush-steppe ecosystem is 

considered one of the greatest 

restoration challenges in the Great Basin 

(Bunting et al. 2003, pp. 82-84). 

Moreover, the threats to L. papilliferum 

can reasonably be anticipated to 

continue or increase. This information, 

in concert with the observed negative 

association between these threats and 

the abundance of the species (in the 

further context of considerations such as 

the limited geographic extent of the 

species’ range and the finite nature of its 

slickspot microhabitats), lead us to the 

conclusion that it is reasonable to 

anticipate that L. papilliferum is likely 

to become endangered in the foreseeable 

future. Based on our assessment of the 

best scientific and commercial data 

available regarding the past, present, 

and future threats faced by the species, 

we have therefore determined that L. 

papilliferum is a threatened species, as 

defined by the Act. 

Seed Dispersal 

(5) Comment: One peer reviewer 

suggested that the seeds of L. 

papilliferum can be widely dispersed by 

high winds, in addition to potential 

dispersal by animals. This reviewer 

stated that the seeds produce mucilage 

when wet and may likely have been 

dispersed by clinging to the wool of 

sheep, citing Rollins 1993, and suggests 

that L. papilliferum is not necessarily so 

highly specialized in its habitat 

requirements, but that the current 

distribution of L. papilliferum may be 

due to the past activities of Basque 

sheep herders. 

Our Response: We acknowledge that 

the seeds of Lepidium papilliferum may 

occasionally be dispersed by wind. 

However, the species does not 

demonstrate any of the usual 

adaptations to assist in wind dispersal, 

such as winged seeds, that would 

indicate wind as the usual mode of 

dispersal for the species. In the paper 

cited by the reviewer, Rollins (1993, p. 

535) suggests that the seeds of plants in 

the genus Lepidium may potentially be 

dispersed by sheep; this study was not 

specific to L. papilliferum, but appears 

to be more relevant to weedy Lepidium 

species of Europe and Asia, such as L. 

perfoliatum. In evaluating whether the 

present range of L. papilliferum may be 

due to the activities of either wind or 

Basque sheepherders, we considered 

both the current knowledge of the range 

of L. papilliferum and the results of 

recent genetic studies. Lepidium 

papilliferum is endemic to southwest 

Idaho, and the best available 

information indicates that there are no 

populations reported in other States 

where the Basques from Idaho would 

have also ranged with their sheep, thus 

indicating that sheep were likely not the 

primary vectors for seed dispersal that 

resulted in the current range of the 

species. In addition, if wind dispersal 

defined the range of the species, we 

would not expect the species to be 

confined to this limited range in 

southwest Idaho, as the wind would 

certainly be capable of carrying seeds 

beyond the present boundaries within 

which L. papilliferum is found. Finally, 

genetic studies showing that smaller 

populations of L. papilliferum have 

reduced genetic variability (Larson et al. 

2006, p. 17) is not consistent with the 

theory that the seeds are winddispersed, which would provide a 

consistent source of genetic mixing and 

reduce the genetic isolation of these 

small populations, thereby maintaining 

genetic diversity. We therefore conclude 

that seed dispersal by wind or sheep is 

most likely not responsible for the 

current distribution of L. papilliferum, 

nor are these processes currently 

occurring at a level that is significant to 

the life history of the species. 

Summary of Public Comments and 

Recommendations 

Since the proposed rule was 

reinstated by the Court, there have been 

two public comment periods. During the 

September 19, 2008, 30–day comment 

period for the proposed rule, we 

received a total of seven comment 

letters in response to our request for 

new information: two from Federal 

agencies and five from organizations or 

individuals. The State of Idaho 

submitted comments and new 

information after the close of the 

comment period. During the March 17, 

2009, 30–day comment period, we 

received 14 comments, including 6 

solicited from peer reviewers. Of the 

public comments, all were received 

either in written form or through the 

portal at: http://www.regulations.gov. 

Two public commenters generally 

supported the proposed rule to list the 

species; seven were opposed to the 

proposed rule, and the remaining were 

either neutral or provided new 

information regarding the proposed 

rule. Comments that provided new 

information were incorporated into this 

final determination, or are addressed 

below. Public comments received were 

grouped into six general issues, and are 

addressed in the following summary. 

Public Comments 

New Information 

(6) Comment: Several commenters 

provided new data and information 

regarding the biology, ecology, life 

history, and threat factors affecting 

Lepidium papilliferum, and requested it 

be incorporated into the body of existing 

information the Service has on the 

species and be considered by us in 

making any future listing 

determinations. 

Our Response: We thank the 

commenters who provided new data 

and information for our consideration in 

making this final listing determination. 

We have considered scientific and 

commercial information regarding 

Lepidium papilliferum contained in 

over 100 technical documents, 

published journal articles, and other 

general literature documents, including 

over 50 documents we have received 

since the January 2007 withdrawal of 

the proposed rule to list L. papilliferum 

(72 FR 1622; January 12, 2007). The 

body of available information specific to 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52057 

L. papilliferum has increased since 

2007, including new scientific 

information regarding the species’ 

biology, ecology, and distribution; 

habitat quality monitoring; the 

implementation and effectiveness of 

ongoing conservation efforts; and 

information pertaining to threat factors 

affecting the species. This information 

was contained in State Agency reports 

(ICDC 2007a; ICDC 2007b; Quinney 

2007; ICDC 2008; IDFG 2008; State of 

Idaho 2008; Unnasch 2008; Colket 2009; 

Robertson and White 2009) and other 

scientific reports and peer-reviewed 

articles (Billinge and Robertson 2008; 

Palazzo et al. 2008; Smith et al. in 

press). We also considered information 

contained in population survey and 

monitoring reports (Boise Airport 2003; 

Hoffman 2005; ICDC 2007b; Quinney 

2007; U.S. Air Force (CH2MHill 

2007a,b, 2008a,b); U.S. BLM 2007, 

2008a; Cole 2008; Colket 2009). 

Additionally, to gain a better 

understanding of existing monitoring 

data, we contracted with independent 

consultants to conduct several analyses, 

including: a statistical analysis on longterm monitoring data collected at the 

OTA, an analysis of rangewide HIP data, 

and an assessment of the methodologies 

of other recent analyses (Sullivan and 

Nations 2009); a statistical and 

geospatial analysis of data collected 

during 2000-2002 field surveys at the 

Inside Desert of the Owyhee Plateau 

(Popovich 2009); and a geospatial 

analysis of wildfire and vegetation types 

within the range of L. papilliferum 

(Stoner 2009). Finally, in order to assess 

any potential relationship between 

abundance or density of L. papilliferum 

and precipitation trends over time, we 

conducted our own analysis of 

precipitation patterns at the OTA 

(Zwartjes 2009). All of the documents 

were made available to the public and 

provided to the six peer reviewers. 

Appropriate Listing Status of Lepidium 

papilliferum 

(7) Comment: One commenter stated 

that the Service should immediately 

move to list Lepidium papilliferum as 

endangered and simultaneously 

designate critical habitat. Conversely, 

the State of Idaho ‘‘remains steadfast in 

its belief that the species does not 

warrant this protection’’ (see State of 

Idaho comments, below). One other 

commenter agreed with this position 

and two commenters indicated that 

there is inadequate scientific 

information to make a decision to list L. 

papilliferum at this time, and requested 

additional studies be completed. 

Our Response: Section 4(b)(1)(A) of 

the Act requires us to make listing 

decisions based solely on the best 

scientific and commercial data 

available. The Service has a legal 

obligation to make a determination 

based on the best available data before 

us at the time the decision is being 

made; the statute does not provide for 

additional research, nor does it provide 

the option of not making a 

determination. We have thoroughly 

reviewed all available scientific and 

commercial data for Lepidium 

papilliferum in preparing this final 

listing determination. We reviewed 

historical and recent publications as 

well as unpublished reports concerning 

L. papilliferum and the sagebrushsteppe habitat where it occurs in 

southwestern Idaho. In addition, we 

utilized peer review to provide a more 

focused, independent examination of 

the available scientific information and 

its application to the current status of 

the species. Finally, we contracted with 

independent consultants to assist us in 

analyzing L. papilliferum abundance 

and habitat quality monitoring data. As 

described in our response to peer review 

comments above (number 2), as part of 

our evaluation, we carefully consider 

the quality and reliability of all data to 

decide which constitutes the best 

available data for our consideration in 

making our final determination. 

Our evaluation of the significance of 

the threat factors across the range of 

Lepidium papilliferum is presented in 

the Summary of Factors Affecting the 

Species section of this final 

determination. Additional discussion of 

our application of the standards of the 

Act in making our determination is 

provided in our response to peer review 

comment number 4, above. Lepidium 

papilliferum is currently affected by 

threat factors across its entire 

geographic range. Based on our 

evaluation, we believe it is reasonable to 

anticipate that the negative impacts of 

these threats on L. papilliferum 

rangewide will continue and even 

increase. Although we consider the 

impacts of these threats to be 

foreseeable and likely to result in the 

species becoming endangered within 

the foreseeable future, we do not 

consider L. papilliferum to be currently 

in danger of extinction. Furthermore, 

while we acknowledge the efforts of the 

State and other entities to implement 

conservation measures for the species, 

the best available information leads us 

to believe that currently available 

management tools are not capable of 

effectively reducing or ameliorating 

these threats across the range of the 

species. Based on our assessment of the 

best scientific and commercial data 

available regarding the threats faced by 

the species, we have determined that L. 

papilliferum meets the definition of a 

threatened species under the Act. We 

have also determined that designating 

critical habitat for L. papilliferum is 

prudent but not determinable at this 

time (see Critical Habitat 

Determinability, below). 

Taxonomic Status of Lepidium 

papilliferum 

(8) Comment: One commenter 

suggested that Lepidium papilliferum is 

a local variation of Lepidium 

montanum, and therefore is not a 

species or subspecies as defined under 

the Act. Another commenter stated that 

considerable uncertainty remains 

regarding the taxonomy of L. 

papilliferum and suggested that the 

Service conduct a genetic study to 

resolve any taxonomic disputes. 

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 1993 review of taxa in 

the mustard family (Brassicaceae), 

Rollins maintained the species as L. 

papilliferum based on differences in the 

physical features between the two 

species such as: 

(1) L. papilliferum has trichomes 

(hair-like structures) occurring on the 

filaments of stamens (the part of flower 

that produces pollen), but L. montanum 

does not; 

(2) All the leaves on L. papilliferum 

are pinnately divided whereas L. 

montanum has some leaves that are not 

divided; 

(3) The shape of the seed capsule 

(silicle [silique]) 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. In addition, 

Meyer et al. (2005, p. 17) describe a 


srobinson on DSKHWCL6B1PROD with RULES4
52058 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

contrast in life history when compared 

to L. montanum regarding seed 

dormancy and the seed bank. Lepidium 

papilliferum seeds can remain dormant 

(and viable) and persist in the seed bank 

for up to 12 years; in contrast, L. 

montanum has largely nondormant 

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

Resolving one commenter’s concern, a 

recent genetic study compared L. 

montanum, L. papilliferum, and L. 

fremontii. Results of the study indicated 

that L. fremontii and L. papilliferum are 

morphologically and ecologically 

distinct from L. montanum, with 

apparently little gene flow between L. 

fremontii and L. papilliferum, and L. 

montanum (Smith et al. in press, p. 18). 

Lepidium papilliferum is recognized as 

a distinct species by Intermountain 

Flora (Holmgren et al. 2005, p. 259), the 

U.S. Department of Agriculture’s 

‘‘PLANTS Database’’ (USDA 2006), and 

the Biota of North America Project (ITIS 

2009). After considering all of this 

information, we believe that L. 

papilliferum is properly recognized as a 

full species, separate from L. 

montanum. 

The Act requires the Service to use 

the best scientific data available when 

making listing determinations under 

section 4 of the Act. The Act, therefore, 

does not require the Service to conduct 

its own studies on species it is 

considering for protection under the 

Act, including genetic studies on the 

taxonomy of those species. 

Conservation Agreements 

(9) Comment: One commenter stated 

that the 2003 Candidate Conservation 

Agreement for Slickspot Peppergrass 

(CCA) by the State of Idaho, BLM, and 

others ‘‘falsely assured’’ readers that it 

would protect Lepidium papilliferum 

and its habitat. We also received 

information from the State of Idaho and 

the BLM describing ongoing 

conservation actions they are 

implementing under the CCA. 

Our Response: We strongly support a 

collaborative conservation effort to 

address factors affecting species being 

considered for listing under the Act. 

Since February 2000, we have worked 

with numerous agencies and 

individuals to assess the status of 

Lepidium papilliferum and to identify 

and implement conservation actions on 

its behalf. We continue to participate as 

a technical advisor to an interagency 

group of biologists and stakeholders to 

share scientific information and 

coordinate conservation actions for L. 

papilliferum and its habitat. 

In 2006, as part of a previous status 

review for Lepidium papilliferum, we 

conducted an evaluation of individual 

conservation efforts contained in five 

different plans, or conservation 

strategies, developed for L. papilliferum. 

These five plans were: (1) the 2003 CCA; 

(2) the Idaho Army National Guard 

(IARNG) Integrated Natural Resource 

Management Plan (INRMP) for Gowen 

Field/Orchard Training Area; (3) the 

U.S. Air Force INRMP for Mountain 

Home Air Force Base; (4) the 

Conservation Agreement by and 

between the City of Boise and the 

Service for Allium aasea (Aase’s onion), 

Astragalus mulfordiae (Mulford’s 

milkvetch) and L. papilliferum, also 

known as the Hull’s Gulch Agreement; 

and (5) the Conservation Agreement for 

slickspot peppergrass (Lepidium 

papilliferum) at the Boise Airport, Ada 

County, Idaho. 

The majority of the conservation 

efforts developed on behalf of Lepidium 

papilliferum that we examined are 

contained in the 2003 State of Idaho 

CCA, which was updated in 2006. The 

CCA includes efforts that are intended 

to address the need to maintain and 

enhance L. papilliferum habitat; reduce 

the intensity, frequency, and size of 

natural and human-caused wildfires; 

reduce the potential for invasion of 

nonnative plant species from wildfire; 

minimize the loss of the species’ habitat 

associated with rehabilitation and 

restoration techniques; minimize the 

establishment of invasive nonnative 

species; mitigate the negative effects of 

military training and other associated 

activities; and minimize the impact of 

ground disturbances caused by livestock 

penetrating trampling during periods 

when soils are saturated. The IDARNG 

and U.S. Air Force are also 

implementing conservation efforts on 

lands they manage to potentially avoid 

or reduce adverse effects of military 

training on L. papilliferum and its 

habitat. For example, the IDARNG has 

been implementing conservation efforts 

at the OTA since 1991 that promote the 

conservation of L. papilliferum, while 

still providing for military training 

activities. These actions include 

intensive wildfire suppression efforts, 

and restricting ground operated military 

training to areas where the plants are 

not found. The U.S. Air Force INRMP 

was modified in 2004 and contains 

more measures that promote the 

conservation of L. papilliferum than the 

2000 version. The current INRMP 

includes measures developed to 

minimize the effects of threats such as 

wildfire, nonnative invasive weeds, and 

livestock use on L. papilliferum. The 

Boise Airport Conservation Agreement 

lays out measures to protect and 

conserve the known occurrences of L. 

papilliferum at the airport, while the 

Hull’s Gulch Conservation Agreement 

focuses on coordinating and planning 

activities with the Service in Hull’s 

Gulch in the Boise Foothills. 

With the exception of conservation 

efforts implemented by the IDARNG 

over the past 18 years, many of the 

conservation efforts presented in the 

conservation plans, although laudable, 

have not been implemented over a 

period of time long enough for 

effectiveness to be adequately 

demonstrated. Similarly, the adaptive 

management provisions in the 2003 

State of Idaho CCA have not been 

implemented long enough to have 

sufficient certainty of their effectiveness 

in addressing the long-term 

conservation of L. papilliferum. We 

recognize the conservation efforts 

identified in the conservation plans can 

have benefits for the species and its 

habitat, particularly with limiting the 

effects of wildfire and livestock use. 

Despite the best intentions, however, 

many of the measures identified in the 

conservation plans are limited in their 

ability to effectively reduce long-term 

habitat degradation or loss in the 

sagebrush-steppe ecosystem, including 

the negative impacts observed on 

slickspots and L. papilliferum 

associated with that degradation or loss. 

For example, there is currently no 

effective control of Bromus tectorum 

available to mitigate its effect on L. 

papilliferum and its synergistic 

interactions with frequent wildfires to a 

degree sufficient that we would 

consider it no longer a threat to the 

species. 

Climate Change 

(10) Comment: One commenter 

indicated that the effects of global 

warming and climate change on the 

species must be considered in our 

analyses of potential threats to the 

species and its habitat. 

Our Response: We agree, and have 

provided a discussion of the potential 

impacts of climate change on Lepidium 

papilliferum in this rule. In brief, there 

is compelling scientific evidence that 

we are living in a time of rapid, 

worldwide climate change. For 

example, 11 of the last 12 years 

evaluated (1995-2006) rank among the 

12 warmest years in the instrumental 

record of global surface temperature 

(since 1850) (ISAB 2007, p. iii). While 

the effects of global climate change are 

uncertain, it has the potential to affect 

rare plants and their habitats, including 

L. papilliferum. Although the Service 

cannot identify specific potential effects 

on the species at this time, some models 

indicate that climate change may 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52059 

provide an environment conducive to 

further conversion of the sagebrushsteppe ecosystem by invasive nonnative 

annual grasslands, which would have 

negative consequences for L. 

papilliferum; fire frequency and extent 

is predicted to increase as well. 

Although we do not consider climate 

change to pose a significant threat to L. 

papilliferum in and of itself, we do 

consider climate change to be a 

potentially important contributing factor 

to the primary threats of frequent 

wildfire and invasive nonnative plants, 

particularly B. tectorum, and especially 

in regard to our evaluation of the 

likelihood of the continuation of these 

threats into the foreseeable future. A 

complete description of the potential 

effects from climate change and our 

evaluation of this threat is found in 

Factor E of the Summary of Factors 

Affecting the Species discussion. 

Livestock Grazing 

(11) Comment: Two commenters 

provided information to support the 

argument that livestock grazing is 

detrimental to Lepidium papilliferum. 

Four commenters provided comment or 

new information to support the 

countering view, indicating that 

livestock grazing is not detrimental or 

could be beneficial to the species. 

Our Response: Livestock use in areas 

that contain Lepidium papilliferum has 

the potential to result in either positive 

or negative effects on the species, 

depending on a variety of factors such 

as stocking rates and season of use. The 

most visible negative effect on L. 

papilliferum and its slickspot habitat is 

from mechanical disturbance due to 

trampling, which can affect the fragile 

soil layers of slickspots and compromise 

their integrity and function (Seronko 

2004; Meyer et al. 2005, pp. 21-22). 

Livestock trampling and compaction of 

slickspots may also bury seeds to such 

a depth that germination is no longer 

possible (Meyer et al. 2005, pp. 21-22). 

We are aware of three incidents where 

livestock trampling events have 

apparently resulted in a dramatic 

decrease in L. papilliferum numbers at 

sites where the plants were formerly 

abundant, while reduced plant numbers 

were not observed at similar adjacent 

sites within the same year (Robertson 

2003b, p. 8; Meyer et al. 2005, p.22; 

Colket 2006, pp. 10-11). Lepidium 

papilliferum numbers are slowly 

recovering at the site in the Boise 

Foothills (Colket 2009, p. 31), the site at 

the OTA has shown no apparent 

recovery over time (Meyer et al. 2005, 

p.22), and the fate of the third site at 

Glenns Ferry is unknown, as it has not 

been revisited since the event. 

Conversely, it is hypothesized that 

livestock use, at an appropriate level 

and season, may reduce the effect of 

invasive nonnative annual grasses at 

some L. papilliferum sites by reducing 

fine fuel loads, thereby decreasing the 

risk of wildfire (e.g., Loeser et al. 2007, 

p. 94, and references therein; 

Launchbaugh et al. 2008; RomeroCalcerrada et al. 2008, p. 351). Data 

limitations currently make it difficult to 

establish effect thresholds from 

livestock management activities on L. 

papilliferum and its habitat. There have 

been adaptive management techniques 

implemented for livestock use in some 

areas occupied by L. papilliferum, and 

several recent studies have examined 

the relationship between livestock 

trampling effects and L. papilliferum 

abundance (Popovich 2009; Salo 2009; 

Sullivan and Nations 2009). As 

described in detail in ‘‘Livestock Use’’ 

under Factor A in the Summary of 

Factors Affecting the Species section, 

above, we consider the risks associated 

with livestock use, as currently 

practiced, to be a lesser threat than other 

factors that have been demonstrated to 

adversely impact the species rangewide. 

We encourage the continued 

implementation of conservation 

measures and associated monitoring to 

ensure potential impacts of livestock 

trampling to the species are avoided or 

minimized. 

Data Quality and Interpretation 

(12) Comment: 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 and one peer reviewer 

stated that there have been no 

comprehensive systematic surveys for L. 

papilliferum, and therefore, we do not 

fully understand the distribution or 

status of the species. In addition, the 

peer reviewer indicated that the number 

of element occurrences has increased 

between 1998 (45 extant EOs) and 2008 

and will continue to increase. One 

commenter 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. Several 

commenters cited information relating 

L. papilliferum annual abundance to 

precipitation. One commenter and one 

peer reviewer stated that the Service’s 

determination that there is evidence of 

a statistically significant population 

decline ignores the fact that 2008 was 

the highest population year on record. 

Another peer reviewer expressed a lack 

of confidence that the high number of 

plants in 2008 portends any long-term 

increase in the population. One 

commenter stated that the high L. 

papilliferum numbers documented in 

2008 agree with the Service’s 2007 

conclusion that the overall population 

trend for the species is inconsistent. 

Two commenters and one peer reviewer 

stated that the Service should be 

transparent in the quality and source of 

the data used in making our 

determination. 

Our Response: As previously stated, 

we have reviewed and considered 

scientific and commercial data 

contained in numerous technical 

reports, published journal articles, and 

other documents. 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 acknowledge that 

uncertainties exist; however, section 4 

of the Act mandates that we make a 

listing determination based on the best 

scientific and commercial available at 

the time of our determination. 

Our response is grouped by the 

following topics: Survey efforts, 

population trends, 2008 HIP survey 

results, and data quality and 

transparency. 

Survey Efforts: As systematic 

rangewide surveys have not occurred, 

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. However, occupied 

slickspot sites and EOs discovered since 

1998 have not added substantially to 

our knowledge of where the species 

exists; these new sites have all been 

within the known range of the species. 

For example, an inventory survey on 

BLM lands in the Owyhee Plateau 

physiographic region in 2007 

documented 200 slickspots containing 

L. papilliferum plants within the known 

range of the plant (ERO 2008, p. 7). See 

our response to State of Idaho comments 

for additional information on potential 

L. papilliferum survey areas based on a 

recent modeling effort. 

Population Trends: Please see our 

response to peer review comments, 

number 1, above. 

2008 HIP Survey Results: Rangewide, 

more slickspot peppergrass plants were 

counted in 2008 than in any other of the 

5 years of HIP monitoring (Colket 2009, 

p. 26). This result was largely based on 


srobinson on DSKHWCL6B1PROD with RULES4
52060 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

substantial increases in the number of 

slickspot peppergrass plants at only 6 of 

the 80 HIP transects (008A, 027A, 027D, 

066, 067, and 070). Sixty-six percent of 

all slickspot peppergrass plants counted 

in 2008 (27,544 out of 41,672 plants) 

occurred at these 6 HIP transects, which 

represent only 8 percent of the total 

number of HIP transects rangewide 

(Colket 2009, p. 26). Two of the HIP 

transects with high plant numbers in 

2008 (066 and 070) are located in the 

Boise Foothills physiographic region. 

The four remaining HIP transects with 

high plant numbers in 2008 were 

located on the Snake River Plain 

physiographic region, with three of 

these transects being located on the 

OTA (027A, 027D, 067). We cannot 

explain why these six transects 

exhibited such high plant numbers in 

2008, but it should be noted that each 

of these six HIP transects are located in 

areas where the plant community is 

unburned and is dominated by the 

native sagebrush Artemisia tridentata 

(Colket 2009, p. 26). Sites exhibiting 

these characteristics are considered high 

quality habitat for L. papilliferum. 

Data Quality and Transparency: 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 the 

Service’s Information Quality Act 

Guidelines in developing this document 

(USFWS 2007. 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 new 

information available on Lepidium 

papilliferum since January 2007 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 L. papilliferum, and threats 

affecting the species, were derived from 

previous petition findings, previous 

Federal Register notices, Idaho’s 

Natural Heritage Program (formerly 

Idaho Conservation Data Center) EO 

records, and other pertinent references 

from 1897 (when the species was first 

collected) through April of 2009. 

State of Idaho Comments 

(13) Comment: The State of Idaho 

requested the Service conduct an 

independent review of available 

information, including: a third-party 

audit of the monitoring and survey 

information collected by the IDARNG 

and other researchers at the OTA; reexamine the prior inferences the Service 

has drawn from available information; 

apply statistical analysis to the available 

information; and evaluate whether there 

are more, currently undiscovered 

populations. 

Our Response: Prior to making our 

determination in this final rule, the 

Service has considered all of these 

issues and conducted the reviews 

suggested by the State; the results of all 

of these reviews were made available 

during the most recent comment period 

on the proposed rule to list Lepidium 

papilliferum. During the fall of 2008, the 

Service contracted with independent 

consultants to evaluate the various 

monitoring and survey methodologies 

for L. papilliferum and conduct 

statistical analyses on data collected on 

the OTA since 1990. The consultants 

also analyzed the rangewide HIP data 

collected over the past 5 years to 

examine any trends in L. papilliferum 

abundance in relation to environmental 

parameters measured as part of the HIP 

monitoring. In total, the consultants 

examined the four ongoing L. 

papilliferum survey programs 

conducted on the OTA. Three of the 

survey programs are conducted solely 

on the OTA, and two of these (rough 

census and special-use plots) have been 

implemented at the same locations since 

the early 1990s. The third program is a 

block search that looks at both new and 

previously surveyed areas for unknown 

populations of L. papilliferum. The 

fourth survey and monitoring program, 

partially conducted at the OTA, is the 

rangewide HII and HIP monitoring that 

has been performed by the INHP since 

the late 1990s. The results of this 

independent analysis were reported in a 

document titled: Analysis of slickspot 

peppergrass (Lepidium papilliferum) 

population trends on Orchard Training 

Area and Rangewide Implications, cited 

here as Sullivan and Nations (2009). 

The Sullivan and Nations (2009) report, 

as well as a report on the statistical and 

geospatial analysis of data collected 

during the 2000-2002 field surveys at 

the Inside Desert of the Owyhee Plateau 

(Popovich 2009), and a contracted 

geospatial analysis of wildfire and 

vegetation types within the range of L. 

papilliferum (Stoner 2009), were 

provided to the six peer reviewers and 

made available to the public for 

consideration and evaluation of all best 

available scientific and commercial data 

during the second comment period, and 

the results of these independent reports 

and reviews were incorporated into this 

final rule. 

In an effort to evaluate the probability 

that Lepidium papilliferum may be 

found in other areas, the Service 

requested the INHP develop a model for 

predicting L. papilliferum distribution 

based on factors such as elevation, soil 

types, precipitation, and underlying 

geology (Colket 2008, p. 2). This model 

identified several potential areas in 

southwest Idaho with a relatively high 

probability of supporting L. papilliferum 

in areas outside the known range of the 

species. Although preliminary surveys 

of these areas did not result in the 

discovery of additional L. papilliferum 

sites (Colket 2008, pp. 4-6), we believe 

that this model can be used as a tool to 

prioritize areas targeted for future 

surveys and conservation planning 

efforts for L. papilliferum (Colket 2008, 

p. 7). Past searches have occurred for 

this species in Oregon (Findley 2003) 

and outside of its known range in Idaho 

(BLM 2000), but the species has never 

been found in these areas. The BLM is 

aware of our interest in the possible 

location of L. papilliferum in Oregon, 

and their botanists continue to look for 

the species during the course of their 

surveys (Foss 2009), but to date it has 

not been found. The best currently 

available information does not indicate 

that there has been a significant increase 

in the known range of L. papilliferum 

since our 2007 decision. 

In the past, questions were raised 

regarding why expanded surveys on the 

OTA conducted by URS in 2005 

recorded higher numbers of Lepidium 

papilliferum than had been previously 

observed. Sullivan and Nations (2009) 

were able to clarify that the large 

number of L. papilliferum plants 

counted by URS likely resulted from a 

more intensive search effort over a 

larger area in 2005 compared to what is 

normally examined during the rough 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52061 

census or special-use plot monitoring 

efforts (Sullivan and Nations 2009, p. 2). 

Although this survey indicated that 

there were more L. papilliferum on the 

OTA than previously documented, it 

did not increase the known range of the 

species. 

Available Conservation Measures 

Conservation measures provided to 

species listed as endangered or 

threatened under the Act include 

recognition of the status, increased 

priority for research and conservation 

funding, recovery actions, requirements 

for Federal protection, and prohibitions 

against certain practices. Recognition 

through listing results in public 

awareness and conservation by Federal, 

State, and local agencies, private 

organizations, and individuals. The 

listing of Lepidium papilliferum will 

lead to the development of a recovery 

plan for the species. Under section 6 of 

the Act, we would be able to grant funds 

to the State of Idaho for management 

actions promoting the conservation of L. 

papilliferum. A full discussion of the 

ongoing conservation actions by 

Federal, State, and local entities 

involved with Lepidium papilliferum 

conservation is described elsewhere in 

this document (see Evaluation of 

Conservation Efforts, above). 

The Act requires Federal agencies to 

implement recovery actions, as well as 

encourages non-Federal entities to 

support and carry out recovery goals for 

listed species. The protection measures 

required of Federal agencies and the 

prohibitions against certain activities 

involving listed plants are discussed, in 

part, below. 

Section 7(a) of the Act, as amended, 

requires Federal agencies to evaluate 

their actions with respect to any species 

that is proposed or listed as endangered 

or threatened and with respect to its 

critical habitat, if any is designated or 

proposed for designation. Regulations 

implementing this interagency 

cooperation provision of the Act are 

codified at 50 CFR Part 402. Section 

7(a)(2) requires Federal agencies, 

including the Service, to ensure that 

activities they authorize, fund, or carry 

out are not likely to jeopardize the 

continued existence of a listed species 

or to destroy or adversely modify its 

critical habitat if any has been 

designated. If a Federal action may 

affect a listed species or its critical 

habitat, the responsible Federal agency 

must consult with us under the 

provisions of section 7(a)(2) of the Act. 

For Lepidium papilliferum, Federal 

agency actions that may require 

consultation as described in the 

preceding paragraph may include 

actions that would affect slickspot soil 

integrity or function, individual L. 

papilliferum plants, or the seed bank of 

the plant. Such actions may include, but 

are not limited to: soil stabilization and 

rehabilitation activities; wildfire 

suppression and rehabilitation 

activities; construction and maintenance 

of infrastructure such as roads, 

electronic transmission lines, radio 

towers, and buildings; livestock grazing 

permits and other Federal permitting 

actions; livestock range improvements 

by the BLM; or actions undertaken by 

branches of the Department of Defense, 

U.S. Army Corps of Engineers, Federal 

Emergency Management Agency, and 

the Federal Highways Administration. 

Section 7 consultation may also be 

required by the provision of Federal 

funds to State and private entities 

through Federal programs such as the 

Service’s Partners for Fish and Wildlife 

Program and Federal Aid in Wildlife 

Restoration Program, and a variety of 

grants administered by the U.S. 

Department of Agriculture, Natural 

Resources Conservation Service, the 

Federal Housing Administration, and 

the Farm Services Agency. Other 

activities that may require consultation 

include military training activities by 

the Air Force or the Idaho Army 

National Guard. Federal actions not 

affecting the species, as well as actions 

on non-Federal lands that are not 

federally funded, authorized, or 

permitted, do not require section 7 

consultation, although the latter are still 

potentially subject to section 9’s 

prohibitions. 

The Act and its implementing 

regulations set forth a series of general 

prohibitions and exceptions that apply 

to all threatened plants. All prohibitions 

of section 9(a)(2) of the Act, 

implemented by 50 CFR 17.71, apply to 

both endangered and threatened 

species. These prohibitions, in part, 

make it illegal for any person subject to 

the jurisdiction of the United States to 

import or export, transport in interstate 

or foreign commerce in the course of a 

commercial activity, sell or offer for sale 

in interstate or foreign commerce, or 

remove and reduce the species to 

possession from areas under Federal 

jurisdiction. In addition, for plants 

listed as endangered, the Act prohibits 

the malicious damage or destruction on 

areas under Federal jurisdiction and the 

removal, cutting, digging up, or 

damaging or destroying of such plants 

in knowing violation of any State law or 

regulation, including State criminal 

trespass law. Section 4(d) of the Act 

allows for the provision of such 

protection to threatened species through 

regulation. This protection may apply to 

this species in the future if regulations 

are promulgated. Seeds from cultivated 

specimens of threatened plants are 

exempt from these prohibitions 

provided that their containers are 

marked ‘‘Of Cultivated Origin.’’ Certain 

exceptions to the prohibitions apply to 

agents of the Service and State 

conservation agencies. 

The Act and 50 CFR 17.72 also 

provide for the issuance of permits to 

carry out otherwise prohibited activities 

involving threatened plants under 

certain circumstances. Such permits are 

available for scientific purposes and to 

enhance the propagation or survival of 

the species. For threatened plants, 

permits also are available for botanical 

or horticultural exhibition, educational 

purposes, or special purposes consistent 

with the purposes of the Act. We 

anticipate that few trade permits will 

ever be sought or issued for Lepidium 

papilliferum because the species is not 

in cultivation or common in the wild. 

Requests for copies of the regulations 

regarding listed species and inquiries 

about prohibitions and permits may be 

addressed to U.S. Fish and Wildlife 

Service, Endangered Species Permits, 

911 NE. 11th Avenue, Portland, OR 

97232-4181. 

We adopted a policy on July 1, 1994 

(59 FR 34272), to identify to the 

maximum extent practicable at the time 

a species is listed those activities that 

would or would not constitute a 

violation of section 9 of the Act. The 

intent of this policy is to increase public 

awareness of the effect of the listing on 

future and ongoing activities within a 

species’ range. We believe that based 

upon the best available information, the 

actions listed below would not result in 

a violation of section 9 of the Act 

provided these activities are carried out 

in accordance with existing regulation 

and permit requirements: 

(1) Activities authorized, funded, or 

carried out by Federal agencies (e.g., 

grazing management, agricultural 

conversions, range management, rodent 

control, mineral development, road 

construction, human recreation, 

pesticide application, controlled burns) 

and construction/maintenance of 

facilities (e.g., fences, power lines, 

pipelines, utility lines) when such 

activity is conducted according to any 

reasonable and prudent measures 

prescribed by the Service in a 

consultation conducted under section 7 

of the Act; and 

(2) Casual, dispersed human activities 

on foot (e.g., bird watching, sightseeing, 

photography, and hiking). 

The actions listed below may 

potentially result in a violation of 


srobinson on DSKHWCL6B1PROD with RULES4
52062 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

section 9 of the Act; however, possible 

violations are not limited to these 

actions alone: 

(1) Unauthorized collecting of the 

species on Federal Lands; 

(2) Interstate or foreign commerce and 

import/export without previously 

obtaining an appropriate permit. 

Permits to conduct activities are 

available for purposes of scientific 

research and enhancement of 

propagation or survival of the species. 

Questions regarding whether specific 

activities, such as changes in land use, 

will constitute a violation of section 9 

should be directed to the Idaho Field 

Office (see ADDRESSES section). 

Critical Habitat 

Critical habitat is defined in section 3 

of the Act as: ‘‘(i) The specific areas 

within the geographical area occupied 

by the species, at the time it is listed in 

accordance with the provisions of 

section 4 of this Act, on which are 

found those physical or biological 

features (I) essential to the conservation 

of the species and (II) which may 

require special management 

considerations or protection; and (ii) 

specific areas outside the geographical 

area occupied by the species at the time 

it is listed in accordance with the 

provisions of section 4 of the Act, upon 

a determination by the Secretary of the 

Interior that such areas are essential for 

the conservation of the species’’ (16 

U.S.C. 1532(5)(A)). 

Conservation, as defined under 

section 3(3) of the Act, means ‘‘the use 

of all methods and procedures which 

are necessary to bring any endangered 

or threatened species to the point at 

which the measures provided under this 

Act are no longer necessary. Such 

methods and procedures include, but 

are not limited to, all activities 

associated with scientific resources 

management such as research, census, 

law enforcement, habitat acquisition 

and maintenance, propagation, live 

trapping, and transplantation, and, in 

the extraordinary case where population 

pressures within a given ecosystem 

cannot be otherwise relieved, may 

include regulated taking’’ (16 U.S.C. 

1532(3)). 

The primary regulatory effect of 

critical habitat is the requirement, under 

section 7(a)(2) of the Act, that Federal 

agencies shall ensure that any action 

they authorize, fund, or carry out is not 

likely to result in the destruction or 

adverse modification of designated 

critical habitat. Section 7(a)(2) of the Act 

requires consultation on Federal actions 

that may affect critical habitat. The 

designation of critical habitat does not 

affect land ownership or establish a 

refuge, wilderness, reserve, preserve, or 

other conservation area. Such 

designation does not allow the 

government or public to access private 

lands. Such designation does not 

require implementation of restoration, 

recovery, or enhancement measures by 

private landowners. Where a landowner 

requests Federal agency funding or 

authorization for an action that may 

affect a listed species or critical habitat, 

the consultation requirements of section 

7(a)(2) of the Act would apply, but even 

in the event of a destruction or adverse 

modification finding, the landowner’s 

obligation is not to restore or recover the 

species, but to implement reasonable 

and prudent alternatives to avoid 

destruction or adverse modification of 

critical habitat. 

For inclusion in a critical habitat 

designation, the habitat within the 

geographical area occupied by the 

species at the time of listing must 

contain the physical and biological 

features essential to the conservation of 

the species, and be included only if 

those features may require special 

management considerations or 

protection. Critical habitat designations 

identify, to the extent known using the 

best scientific data available, habitat 

areas that provide essential life cycle 

needs of the species (i.e., areas on which 

are found the primary constituent 

elements (PCEs) laid out in the 

appropriate quantity and spatial 

arrangement for the conservation of the 

species). Under the Act, we can 

designate critical habitat in areas 

outside the geographical area occupied 

by the species at the time it is listed 

only when we determine that those 

areas are essential for the conservation 

of the species. 

Section 4 of the Act requires that we 

designate critical habitat on the basis of 

the best scientific and commercial data 

available. Further, our Policy on 

Information Standards Under the 

Endangered Species Act (59 FR 34271; 

July 1, 1994), the Information Quality 

Act (section 515 of the Treasury and 

General Government Appropriations 

Act for Fiscal Year 2001 (Pub. L. 106- 

554; H.R. 5658)), and our associated 

Information Quality Guidelines issued 

by the Service, provide criteria, 

establish procedures, and provide 

guidance to ensure that our decisions 

are based on the best scientific data 

available. They require our biologists, to 

the extent consistent with the Act and 

with the use of the best scientific data 

available, to use primary and original 

sources of information as the basis for 

recommendations to designate critical 

habitat. 

When we are determining which areas 

should be designated as critical habitat, 

our primary source of information is 

generally the information developed 

during the listing process for the 

species. Additional information sources 

may include the recovery plan for the 

species, articles in peer-reviewed 

journals, conservation plans developed 

by States and counties, scientific status 

surveys and studies, biological 

assessments, or other unpublished 

materials and expert opinion or 

personal knowledge. 

Prudency Determination 

Section 4(a)(3) of the Act, as 

amended, and implementing regulations 

(50 CFR 424.12), require that, to the 

maximum extent prudent and 

determinable, the Secretary designate 

critical habitat at the time a species is 

determined to be endangered or 

threatened. Our regulations (50 CFR 

424.12(a)(1)) state that the designation 

of critical habitat is not prudent when 

one or both of the following situations 

exist: ‘‘(i) [t]he species is threatened by 

taking or other human activity, and 

identification of critical habitat can be 

expected to increase the degree of such 

threat to the species, or ii) [s]uch 

designation of critical habitat would not 

be beneficial to the species.’’ 

There is no documentation that 

Lepidium papilliferum is threatened by 

taking or other human activity. In the 

absence of finding that the designation 

of critical habitat would increase threats 

to a species, if there are any benefits to 

a critical habitat designation, then a 

prudent finding is warranted. The 

potential benefits include: (1) Triggering 

consultation under section 7 of the Act 

for actions in which there may be a 

Federal nexus where it would not 

otherwise occur because, for example, 

the area is or has become unoccupied or 

the occupancy is in question; (2) 

focusing conservation activities on the 

most essential features and areas; (3) 

providing educational benefits to State 

or county governments or private 

entities; and (4) preventing people from 

causing inadvertent harm to the species. 

The primary regulatory effect of a 

critical habitat designation is the section 

7(a)(2) requirement that Federal 

agencies refrain from taking any action 

that destroys or adversely affects critical 

habitat. At present, the known extant 

individuals of Lepidium papilliferum 

occur on Federal, State, and private 

land, and all previously known 

occurrences have been on Federal, State, 

and private lands. State and private 

lands that may be designated as critical 

habitat in the future for this species may 

be subject to Federal actions that trigger 


srobinson on DSKHWCL6B1PROD with RULES4
Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 52063 

the section 7 consultation requirement, 

such as the granting of Federal monies 

for conservation projects or the need for 

Federal permits for projects. Therefore, 

since we have determined that the 

designation of critical habitat will not 

likely increase the degree of threat to the 

species and may provide some measure 

of benefit, we find that designation of 

critical habitat is prudent for L. 

papilliferum. 

Critical Habitat Determinability 

As stated above, section 4(a)(3) of the 

Act requires the designation of critical 

habitat concurrently with the species’ 

listing ‘‘to the maximum extent prudent 

and determinable’’ (16 U.S.C. 

1533(a)(3)). Our regulations at 50 CFR 

424.12(a)(2) state that critical habitat is 

not determinable when one or both of 

the following situations exist: 

(i) Information sufficient to perform 

required analyses of the impacts of the 

designation is lacking, or 

(ii) The biological needs of the species 

are not sufficiently well known to 

permit identification of an area as 

critical habitat. 

When critical habitat is not 

determinable, the Act provides for an 

additional year to publish a critical 

habitat designation (16 U.S.C. 

1533(b)(6)(C)(ii)). 

In accordance with section 3(5)(A)(i) 

of the Act and regulations at 50 CFR 

424.12, in determining which areas 

occupied by the species at the time of 

listing to designate as critical habitat, 

we consider those physical and 

biological features essential to the 

conservation of the species that may 

require special management 

considerations or protection. We 

consider the physical or biological 

features to be the PCEs laid out in the 

appropriate quantity and spatial 

arrangement for the conservation of the 

species. The PCEs listed at 50 CFR 

424.12(b) include, but are not limited to: 

(1) Space for individual and 

population growth and for normal 

behavior; 

(2) Food, water, air, light, minerals, or 

other nutritional or physiological 

requirements; 

(3) Cover or shelter; 

(4) Sites for breeding, reproduction, 

rearing of offspring, germination, or 

seed dispersal; and generally 

(5) Habitats that are protected from 

disturbance or are representative of the 

historic geographical and ecological 

distributions of a species. 

Although we have determined that 

the designation of critical habitat is 

prudent for Lepidium papilliferum, new 

and revised information received since 

the 2007 withdrawal notice (72 FR 

1622) has to be evaluated to determine 

the physical and biological features that 

may be essential for the conservation of 

the species in those areas that were 

occupied at the time of listing, or areas 

that may be essential to the conservation 

of the species outside of the area 

occupied at the time of listing. For 

example, we have received new 

information regarding the effects of seed 

predation indicating that this emerging 

threat may have a serious impact on the 

long-term viability of L. papilliferum. 

However, our current understanding of 

the overall significance of this threat is 

limited by its recent discovery and 

having only short-term evaluation 

results available. We also have new 

information indicating that competition 

with nonnative plants in slickspots has 

a significant impact on the ability of L. 

papilliferum to persist in these 

specialized microsites. A thoughtful 

assessment of the designation of critical 

habitat will require additional time to 

evaluate the physical and biological 

features essential to the conservation of 

the species in light of our new 

understanding of these emerging threats. 

Therefore, we find that critical habitat 

for L. papilliferum is not determinable 

at this time. 

Required Determinations 

Paperwork Reduction Act of 1995 (44 

U.S.C. 3501 et seq.) 

This rule does not contain any new 

collections of information that require 

approval by Office of Management and 

Budget (OMB) under the Paperwork 

Reduction Act. This rule will not 

impose recordkeeping or reporting 

requirements on State or local 

governments, individuals, businesses, or 

organizations. An agency may not 

conduct or sponsor, and a person is not 

required to respond to, a collection of 

information unless it displays a 

currently valid OMB control number. 

National Environmental Policy Act 

We have determined that we do not 

have to prepare environmental 

assessments and environmental impact 

statements, as defined under the 

authority of the National Environmental 

Policy Act of 1969 (42 U.S.C. 4321 et 

seq.), in connection with regulations we 

issued under section 4(a) of the Act. We 

published a notice outlining our reasons 

for this determination in the Federal 

Register on October 25, 1983 (48 FR 

49244). 

References Cited 

A complete list of all references cited 

herein is available on the Internet at 

http://www.regulations.gov. In addition, 

a complete list of all references cited 

herein, as well as others, is available 

upon request from the Idaho Fish and 

Wildlife Office (see FOR FURTHER

INFORMATION CONTACT). 

Authors 

The primary authors of this document 

are staff members of the Idaho Fish and 

Wildlife Office, U.S. Fish and Wildlife 

Service (see ADDRESSES). 

List of Subjects in 50 CFR Part 17 

Endangered and threatened species, 

Exports, Imports, Reporting, and 

recordkeeping requirements, 

Transportation. 

Regulation Promulgation 

■ Accordingly, we amend part 17, 

subchapter B of chapter I, title 50 of the 

Code of Federal Regulations, as follows: 

PART 17—[AMENDED] 

■ 1. The authority citation for part 17 

continues to read as follows: 

Authority: 16 U.S.C. 1361-1407; 16 U.S.C. 

1531-1544; 16 U.S.C. 4201-4245; Pub. L. No. 

99-625, 100 Stat. 3500; unless otherwise 

noted. 

■ 2. Amend § 17.12(h) by adding the 

following entry to the List of 

Endangered and Threatened Plants in 

alphabetical order under ‘‘Flowering 

Plants’’: 

§ 17.12 Endangered and threatened 

plants. 

* * * * * 

(h) * * * 

Species 

Historic range Family Status When listed Critical habitat Special rules 

Scientific name Common name 

FLOWERING PLANTS 

* * * * * * * 


srobinson on DSKHWCL6B1PROD with RULES4
52064 Federal Register / Vol. 74, No. 194 / Thursday, October 8, 2009 / Rules and Regulations 

Species 

Historic range Family Status When listed Critical habitat Special rules 

Scientific name Common name 

Lepidium 

papilliferum 

Slickspot 

peppergrass 

U.S.A. (ID) Brassicaceae T 765 NA NA 

* * * * * Dated: September 24, 2009 

Daniel M. Ashe 

Deputy Director, Fish and Wildlife Service 

[FR Doc. E9–24039 Filed 10–7–09; 8:45 am] 

BILLING CODE 4310–55–S 


srobinson on DSKHWCL6B1PROD with RULES4