Species Report for Lane Mountain Milk-Vetch (Astragalus Jaegerianus)

Species Report for Lane Mountain Milk-vetch (Astragalus jaegerianus)

Dave Silverman© used with permission

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

March 2014 Species Report for Lane Mountain Milk-vetch (Astragalus jaegerianus)

GENERAL INFORMATION

Lead Biologist: Judy Hohman, Biologist, Ventura Fish and Wildlife Office

Methodology to Complete the Species Report:

Staff in the Ventura Fish and Wildlife Office (VFWO), Pacific Southwest Regional Office (RO), and the Headquarters Office (HQ) of the U.S. Fish and Wildlife Service (Service) developed and completed this species report for the Lane Mountain milk-vetch (Astragalus jaegerianus). Information in this species report was gathered from a variety of sources, including journal articles, agency reports and coordination with staff from the National Training Center and Fort Irwin (Department of the Army [Army]), and the Bureau of Land Management (BLM), California State Office and Barstow Field Office. The primary sources of new information since the preparation of the 2008 Five-year Review (Service 2008, pp. 4–13) are reports on: (1) research conducted by the University of California, Los Angeles (UCLA), under contract to the Army on the life history of the species; (2) long-term population monitoring conducted by the Army, and (3) land management activities implemented by the Army and the BLM.

BACKGROUND

Key Listing and Recovery Documents:

Listing and Recovery History

1998 Original Listing 2005 Critical Habitat Federal Register (FR) notice: 63 FR 53596 FR notice: 70 FR 18220 Date listed: October 6, 1998 Date issued: April 8, 2005 Entity listed: species (Astragalus jaegerianus) Area designated: 0 acre (ac) (0 hectare (ha)) Classification: Endangered

2008 5-Year Review 2011 Revised Critical Habitat Date Issued: July 10, 2008 FR notice: 76 FR 29108 Recommendation: Downlist to Threatened Date issued: May 19, 2011 Recovery Priority: 6 Area designated: 14,069 ac (5,693 ha)

Introduction

Lane Mountain milk-vetch is an herbaceous perennial species that is restricted in distribution to a small portion of the central Mojave Desert north of Barstow in San Bernardino County, California (Figure 1). It has a unique relationship with nurse shrubs within the mixed desert scrub community where it is found. This relationship appears to provide benefits to both

2 the Lane Mountain milk-vetch in the form of structural support, attenuation from weather extremes, and some protection from predators, and to the nurse shrub in the form of nitrogen fixation in the soil. In our 1998 listing determination adding the species to the List of Endangered Plants under the Endangered Species Act (Act) as amended (16 U.S.C. 1531 et seq.), we determined the species to be endangered due to threats from surface mining, rock and mineral collecting, off-highway vehicle (OHV) activity, military training activities, a potential increase in fire frequency and fire suppression activities, vulnerability to extinction from stochastic (random) natural events, and unplanned destructive human activities because of its limited distribution (63 FR 53596; October 6, 1998).

Figure 1. Distribution Map, Lane Mountain milk‐vetch

Recovery Plan and Species Review History

We prepared a draft recovery plan for the Lane Mountain milk-vetch in 2001. The release of the draft recovery plan was suspended due to the potential for new information to be available from the pending (at that time) census. A schedule for release of a draft recovery plan has not been determined.

In July 2008, we issued a five-year review for the Lane Mountain milk-vetch. Based on the conservation measures for the Lane Mountain milk-vetch described in the recently issued West Mojave Plan (BLM et al. 2005), the conservation measures described in the Army’s recently issued Final Supplemental Environmental Impact Statement for the Army’s Land Acquisition Project for the National Training Center, Fort Irwin, California (Army 2005), and the larger number of Lane Mountain milk-vetch individuals located shortly after the listing compared to those at the time of listing, we recommended that the species be reclassified from endangered to threatened (Service 2008, pp. 1–20).

In addition, we discussed new information on the species and factors that may or are threatening the species, particularly climate change, in the proposed revised designation of critical habitat published on April 1, 2010 (75 FR 16404) and the final revised designation of critical habitat published on May 19, 2011 (76 FR 29108).

Updated Information and Current Species Status

Species Description

Lane Mountain milk-vetch is a member of the pea family (Fabaceae). It is a slender, diffuse plant, 12 to 27.5 inches (in) (30 to 70 centimeters (cm)) tall, with straggling, freely branched stems that arise from a buried root-crown, or caudex (Barneby 1964, p. 485). The leaves have 7 to 15 silvery linear leaflets, 0.2 to 1.0 in (5 to 25 millimeters (mm)) long. Herbage is light-gray or greenish and strigulose (minutely covered with sharp and stiff appressed straight hairs). The flowers, 5 to 15 per stalk, are cream to purple, or lighter with veins of a deeper color. The keel petals are less than 0.4 in (10 mm) long. Fruits are pencil-shaped pods, linear, smooth, and pendant, 0.6 to 1 in (16 to 25 cm) long. Each pod holds from 2 to 14 seeds (Hessing and Shaughnessy 2011, p. 38; Sharifi 2012, in litt, p. 1); seeds weigh from 0.000053 ounces (oz) (1.5 milligrams (mg)) to 0.000764 oz (5.0 mg) (Sharifi in litt. 2003, p. 5). The grayish hue of the Lane Mountain milk-vetch, caused by the presence of L-shaped trichomes (leaf hairs), provides a contrast in color with the stems and foliage of the nurse shrub during the growing season (Gibson et al. 1998, p. 79). Later in the season, the Lane Mountain milk-vetch takes on a rust-colored hue (C. Rutherford, Service botanist, VFWO, Ventura, California pers. obs. 1993). The leaves are typical of full-sun desert species; the leaflets are amphistomatic (have stomata on both upper and lower surface) with stomatal densities of up to 119,354 per in2 (185 per mm2), and have isolateral mesophyll (an internal arrangement of cells within the leaflets that maximizes photosynthetic capability). The stems also have abundant stomata and a cylinder of cortical chlorenchyma (cells containing chloroplasts), implying they also contribute significantly to photosynthesis (Gibson et al. 1998, pp. 77 and 79; Service 2002 Draft Recovery Plan, pp. 2–3).

Taxonomy

Edmund Jaeger first discovered the Lane Mountain milk-vetch in 1939. In 1941, it was collected by Rupert Barneby and Phillip Munz, and described by Munz (Munz 1941). The type locality is 2.0 miles (mi) (3.2 kilometer (km)) south of Jay Mine, about 12.0 mi (19.3 km) south of Goldstone (town) and 30.0 mi (48.2 km) northeast of Yermo, California in Section 33, T13N, R1E at about 3,000 feet (ft) (914 meters (m)) (Krzysik 1994b, p. 53) in the Brinkman Wash- Montana Mine population (see Figure 1 for distribution map). Within the genus Astragalus, this is the only species in the Jaegeriani section of the genus (Barneby 1964, p. 484). No name changes or changes in taxonomic relationship have been made since the listing and the current taxonomy is upheld in the most recent treatment of the genus (Wojciechowski and Spellenberg 2012).

Genetics

Walker and Metcalf (2008a, 2008b) investigated the genetic profile of Lane Mountain milk-vetch. They collected samples from five areas: one each from the Goldstone, Brinkman Wash-Montana Mine, and Paradise Valley populations and two from the Coolgardie Mesa population (see Figure 1) (Walker and Metcalf 2005a, p. 10). Nine individuals were chosen from each population (n = 45) for DNA sequencing (Walker and Metcalf 2008a, p. 14).

Walker and Metcalf reported several findings based on their sequencing data for Lane Mountain milk-vetch. First, the use of DNA sequencing within chloroplast and nuclear genomes for the five loci examined did not detect genetic variation within or between populations (Walker and Metcalf 2008a final report, p. 18). Walker and Metcalf concluded that the 45 individuals of the Lane Mountain milk-vetch sampled are monomorphic (Walker and Metcalf 2008a, p. 18). This lack of variation across all populations of Lane Mountain milk-vetch (Walker and Metcalf 2008a, p. 18) is in contrast to two other sympatric but more widespread species of Astragalus that were also tested (Walker and Metcalf 2005a, p. 18). They concluded that this lack of DNA sequence variation within chloroplasts and nuclear genomes may be due to the small number of Lane Mountain milk-vetch plants and its restricted geographical range, and supports the hypothesis that the Lane Mountain milk-vetch has a low effective population size (Walker and Metcalf 2008a, pp. 18–19). Low effective population size may indicate that the number of individuals that contribute genes to the next generation (e.g., reproduce and have successful recruitment) is small. Factors that influence a reduced effective population size include a fluctuating population size and neighborhood size or dispersal distance (McDonald 2013, p. 2). Populations with continually small effective population sizes will be especially susceptible to the loss and reorganization of variation by genetic drift (Ellstrand and Elam 1993, p. 219). Walker and Metcalf (2008a, p. 19) concluded that their DNA sequence data suggest that the effective population size for Lane Mountain milk-vetch is far below the 2001 census population size of about 5,000 individuals reported by Charis (2002) and demonstrate that Lane Mountain milk- vetch is a narrow endemic, a species that lacks genetic variation, and is susceptible to genetic drift.

Walker and Metcalf (2008b, p. 162) subsequently used a second technique, the genome- wide survey using amplified fragment length polymorphic markers. The objective of this study

was to investigate the level of genetic variation and its partitioning in Lane Mountain milk-vetch (Walker and Metcalf 2008b, p. 168). This technique revealed additional information. First, the eastern and western halves of the Coolgardie Mesa population (i.e., Lane Mountain and Coolgardie) are significantly different from each other using an analysis of molecular comparison (Walker and Metcalf 2008b, p. 165). However, these two populations are more similar to each other than to any of the other populations that were sampled at the Goldstone, Brinkman Wash-Montana Mine, and Paradise Valley populations.

Second, there is a high level of genetic diversity across the range of the Lane Mountain milk-vetch. This level of genetic diversity for a narrow endemic species with small populations and few individuals suggests that Lane Mountain milk-vetch has undergone a recent population contraction or is undergoing a population contraction, such that the populations may have had a recent common history (Walker and Metcalf 2008b, p. 169). Within-population genetic variation was lowest for the Lane Mountain/Coolgardie populations (southwestern most population) and highest for the Goldstone population (northeastern most population) (Walker and Metcalf 2008b, pp. 164–165).

Third, of the total genetic variation observed, most (87 percent) was attributed to differences within populations, while the rest (13 percent) was attributed to differences among populations. These data support the hypothesis that the Lane Mountain milk-vetch has a well- defined population structure across its range with limited gene flow between populations. The data also show that the levels of gene diversity within populations are significantly correlated with population density, not size, while geographic distances and gene flow explain patterns of population structure. These results suggest a breeding strategy for Lane Mountain milk-vetch as a facultative outcrosser that relies more on outcrossing (i.e., pollination that takes place between two different flowers that may or may not belong to the same genetic line) in areas of high plant density and less so in areas of low plant density (Walker and Metcalf 2008b, p. 170; Karron 1989, pp. 337–338; see Karron 1991, pp. 87–98).

Finally, the analysis of genetic distance and geographic distance data supports an isolation by distance model for the Lane Mountain milk-vetch (i.e., the populations closest to each other have the greatest amount of gene flow). However, the data from population pairwise comparisons and genetic distances for Lane Mountain milk-vetch also suggest that the geographic arrangement of the populations follows the one-dimensional stepping stone model (Walker and Metcalf 2008b, p. 170); that is, the populations that make up the species are arrayed on a geographic line and migration of genetic material occurs only between adjacent populations (Matsen and Wakely 2006, p. 702). This suggests that no gene flow may occur between the Coolgardie Mesa population and the Brinkman Wash Montana Mine or Goldstone populations; and between the Goldstone population and the Paradise Valley or Coolgardie Mesa populations.

Species Biology

Life Cycle Overview

In this section, we give a brief overview of some aspects of the life cycle of the Lane Mountain milk-vetch (see Figure 2). In the section on Demography and Population Trends

below, we discuss how variations in annual climatic conditions affect each life history stage of the species and its long-term persistence.

Lane Mountain milk-vetch is an herbaceous perennial species; it has a taproot that is perennial and an aboveground portion of the plant that is herbaceous and seasonal. The aboveground portion typically grows in a zigzag pattern twining up through a low woody shrub that it uses for structural support like a trellis (see Nurse shrubs and influence on microclimate and microhabitat of Lane Mountain milk-vetch below). Sufficient winter rainfall triggers resprouting from the taproot, and growth of the above ground portion of the plant usually begins in late fall or winter (Charlton 2007, p. 30). From late winter through mid-spring, Lane Mountain milk-vetch produces flowers, fruits, and seeds; it depends on seed to recruit new individuals (Prigge et al. 2006, p. 7). By late spring, Lane Mountain milk-vetch typically dies back when soil moisture has been depleted (Bagley 1999, p. 2; Charlton 2007, p. 30), indicating the end of the growing season. It persists through the dry season as a taproot.

seedbank

senescent seedling

adult juvenile (1st (reproductive) year)

Figure 2. Life Cycle Overview

Although considered cryptic because it usually grows up through a small shrub, it is cryptic some of the time and conspicuous at other times. During low rainfall years, Lane Mountain milk-vetch plants may grow barely 3 in (7.6 cm) tall before flowering, which means it can only be observed under the canopy of the trellis shrub (Charlton 2007, p. 25). However, its cream to purple flowers with darker purple nectar guides are scattered on long stems, and the brown-purple pendulous leathery pods can be quite dense, making the plant most observable in either flower or fruit (Charlton 2007, p. 25). In high rainfall years, Lane Mountain milk-vetch plants overtop the trellis shrubs making it much easier to observe (Charlton 2007, p. 25). By June, most Lane Mountain milk-vetch plants are dormant, with some leaving dry skeletons that are easy to see; skeletons may be visible a year, and occasionally 2 years later.

Reproduction and Recruitment

Flower Production and Pollination Ecology

The flowering season for Lane Mountain milk-vetch is typically from March through May when sufficient rainfall occurs (Charis 2002, p. 8) (Kearns 2003, pp. 12–13). Lane Mountain milk-vetch has substantial reproductive potential with a large plant able to produce more than 900 flowers and 3,000 ovules in a year with high precipitation, but average flower production is less in smaller plants and in years with less favorable precipitation Huggins et al. (2011, p. 33).

Two studies on the pollination ecology of Lane Mountain milk-vetch were conducted between 2002 and 2005 (Kearns 2003; Hopkins 2005). Kearns’ study was hampered by weather conditions before and during the study, yielding a small sample size of Lane Mountain milk- vetch plants in bloom (Kearns 2003, p. 5). Kearns observed 30 different insect species visiting flowers of all plant species at the location of the Lane Mountain milk- vetch’s Paradise Valley population but only 4 pollinator species visiting Lane Mountain milk-vetch plants during daylight hours for a 7-day period (Kearns 2003, pp. 5, 7, and 9). He identified one major pollinator, Anthidium dammersi, a solitary bee in the Megachilidae family, and three occasional visitors, a hoverfly (Eupeodes volucris), a large anthophorid bee (Anthophora sp.), and the white-lined sphinx moth (Hyles lineata) (Kearns 2003, p. 9). Anthidium dammersi occurs in the Mojave and Colorado deserts of California, Nevada, and Arizona (Kearns 2003, p. 12). It will fly up to 0.6 mi (1.0 km) from its nest, although, if floral resources are abundant, it will decrease its flight distances accordingly (Yanega, pers. comm. 2003). Kearns (2003, p. 13) found that the Anthidium individuals he inspected carried pollen primarily from phacelia (Phacelia distans) (82 percent of individuals) and Lane Mountain milk-vetch (64 percent of individuals).

Hopkins conducted her pollinator study at the Coolgardie population of the Lane Mountain milk-vetch in April 2004, and the Coolgardie and Goldstone populations in March and April 2005. She observed six taxa of insects visiting the flowers of the Lane Mountain milk- vetch (three bee species, one bee fly species, one hoverfly species, and one beetle species (Hopkins 2005b, p. 1) Although six insect taxa have been observed on flowers of the Lane Mountain milk-vetch, some are considered nectar and pollen robbers and not pollinators of the milk-vetch. Data from both these studies are summarized in Table 1 below.

Yanega identified the three bee species as Osmia laisulcata, Anthidium emarginatum, and Anthidium dammersi, all of which belong to the megachilid family (Hopkins 2005b, p. 1). These three bees (Anthidium dammersi, A. emarginatum, and Osmia latisculata) are likely effective

pollinators of Lane Mountain milk-vetch (Kearns 2003, pp. 9, 10, and 12; Hopkins 2005b, pp. 1–2). Hopkins also observed two species of flies associated with Lane Mountain milk-vetch flowers, but concluded that the common hoverfly (Eupeodes volucris) and bee fly (Lordotus albidus) were not effective pollinators of Lane Mountain milk-vetch flowers (Hopkins 2005b, p. 1) because both fly species were too lightweight to manipulate the Lane Mountain milk-vetch flower petals and enter the corolla to collect pollen.

Table 1. Summary of data collected by Kearns (2003) and Hopkins (2005 a, 2005b, 2005c) on visitors to and pollinators of flowers of the Lane Mountain milk‐vetch (LMMV).

Year Effective LMMV 2004 and 2005 2003 Taxon of Flower Visitor Pollinator (Hopkins) (Kearns) Leafcutter bee Coolgardie Mesa NE Yes (prefer pea Osmia latisulcata family) Leafcutter bee Goldstone Paradise Yes, Females only Anthidium dammersii Valley (prefer pea family) Leafcutter bee Coolgardie Mesa NE Yes, Females only Anthidium emarginatum and W (prefer pea family) Goldstone, Coolgardie Paradise No-Nectar feeder Hoverfly Mesa NE, and Valley only Eupeodes volucris Coolgardie Mesa W Bee fly (2005b) Coolgardie No-Nectar feeder Lordotus albidus only White-lined sphinx moth Paradise No- Hyles lineata Valley Miner bee Coolgardie Mesa NE, Paradise No (Family Anthophoridae) Coolgardie MesaW Valley Bee fly, Tribe Anthracini Coolgardie Mesa NE No (Family Bombiliidae)

The extent to which Lane Mountain milk-vetch relies on these and other pollinators to achieve seed set in the wild is not known. Under greenhouse conditions, Rundel et al. (2005, pp. 58, 60) found that the number of flowers producing seed resulting from pollination manipulations was higher (ranging from 30 to 40 percent) than the number of flowers producing seed without being pollinated (8 percent); these results support the importance of pollinators in achieving seed production for the Lane Mountain milk-vetch. This is also consistent with pollinator-dependence documented in other species of Astragalus (Karron 1987, pp. 179–193).

Fruit and Seed Production, Germination, and Viability

Among study plots located within the four populations of the Lane Mountain milk-vetch, 167 of 196 observed plants produced flowers and at least one fruit in 2011 (Hessing and Shaughnessy 2011, p. 37). Reproductive effort (as measured by number of fruits per plant) was lowest in the plots in the Coolgardie population, greatest in Paradise population, and

significantly different between the plots when grouped and compared between the populations. Recalling that the Coolgardie population has the greatest number of Lane Mountain milk-vetch plants, the data indicate that reproductive effort in 2011 was lowest in the largest population (Hessing and Shaughnessy 2011, p. 38).

Production: Not all Lane Mountain milk-vetch flowers become fruits and not all fruits mature and release viable seeds. During dry years, plants may desiccate prior to setting seed (Service 2003 proposed CH, p. 8). Charlton (2007, p. 27) reported that Lane Mountain milk- vetch plants will stay small and abort flowers if not enough rainfall occurs. During the 2011 field study, Hessing and Shaughnessy (2011, p. 38) observed that most tagged flowers and fruits disappeared before developing into mature fruits. They hypothesized that the loss of flowers and fruits was caused by abortion due to below normal precipitation, herbivory, wind damage, investigator damage, or some other cause of failure. Huggins et al. (2011, p. 33) also studied flower, fruit, and seed production of the Lane Mountain milk-vetch in the wild. They reported that although Lane Mountain milk-vetch has significant reproductive potential with a large plant able to produce more than 900 flowers and 3,000 ovules in a year with high precipitation, an average of only 163 fruits and 1,372 seeds were ultimately produced per plant in 2010. Lane Mountain milk-vetch plants lost most of their reproductive potential through the loss of flowers (82 percent), and secondarily through the loss of ovules due to lack of fertilization and aborted seed (56 percent). They found that only 17.2 percent of flowers produced fruit, and within these fruit, only 44 percent of ovules ripened into viable seed (p. 31). The 56 percent loss of ovules to seed was caused by lack of fertilization (37 percent) and aborted seed (19 percent). Seed production between study plants was highly variable ranging from 5,345 seeds for one plant to zero (Huggins et al. 2011, p. 32).

Huggins et al. (2011, p. 36) noted that Lane Mountain milk-vetch plant size is strongly correlated with its nurse shrub size, and both nurse shrub and Lane Mountain milk-vetch plant size are correlated to seed production. A larger nurse shrub canopy means a larger Lane Mountain milk-vetch plant and more seed production.

Germination: Lane Mountain milk-vetch responds to rain and has been observed sprouting any time in the field between January and March and after summer rains (Charlton 2007, p. 28). This observation is contradicted by Huggins et al. (2012b, p. 9), who reported that when summer precipitation occurred, they never observed summer rains to break dormancy of Lane Mountain milk-vetch seed.

From greenhouse studies, we know that Lane Mountain milk-vetch seeds can germinate under a wide range of temperature conditions (from day/night temperature of 41/41 º F (5/5 ºC) to 95/68 ºF (35/20 ºC) if soil water supply is not a limiting factor (Rundel et al. 2005, p. 41). This implies that historical cold winter and high summer desert temperatures do not inhibit seed germination when there are adequate water supplies. The greatest germination rate was achieved at a moderate day/night temperature 77/59 ºF (25/15 ºC) (Rundel et al. 2005, p. 41).

Seed germination rates in the field likely resemble the low germination rate of 5 percent observed by researchers in germination trials of unscarified (outer cover is not broken) seed (Sharifi in litt. 2004, p. 1). Under controlled greenhouse conditions, 100 percent of the scarified

10 seeds germinated, and were provided sufficient water and maintained weed-free (Rundel et al. 2005, pp. 6, 49). However, in the field, seed production and seed germination rates are low compared to those under greenhouse conditions, even in the most favorable years (see Abundance and Population Trends below). Surveys by UCLA researchers in spring 2005 showed uneven germination results that were lower than expected given the wet 2004–2005 winter conditions (Rundel et al. 2006, p. 26).

Information on the length of time that seeds remain viable is limited. Rundel et al. (2005, p. 31) germinated seed that had been collected the year before. These results indicate that 1-year old seed is viable under ideal germinating conditions. Although little is known about the long- term viability of Lane Mountain milk-vetch seeds in the soil, seed collected in 2001 were found to be viable after nine years of storage at room temperature and ambient humidity (Sharifi and Huggins, unpublished data), suggesting that viability in the soil is likely to exceed 5 years Huggins et al. 2012, p. 6).

Seed Dispersal and Seed Bank Ecology:

Short-distance dispersal: After seed production the pendulous pods of the Lane Mountain milk-vetch split on the distal end and the majority of the small seeds fall on the ground beneath the nurse shrub. Lane Mountain milk-vetch seeds have no specialized dispersal morphologies such as barbs or feathery appendages that would suggest adaptations to dispersal mechanisms of wind or attachment to the fur of animals. Seed pods that remain on the mother plant (aerial seed bank) may fall off weeks to several months later after primary dispersal. Seeds that remain in pods may be protected for a time from weathering and scarification, and may therefore be scarified and germinate later than seeds released individually during primary dispersal.

Granivores (seed-eating animals), such as rodents, ants, and birds, likely consume some portion of the seed produced. Seeds not consumed by granivores are buried beneath the plant litter and soil particulate produced by nurse shrubs that act as traps for wind-blown soil particles (Huggins et al. 2012, pp. 3–4). The relatively large size of these seeds, compared to many desert annual species, makes them an attractive food source to ants and other large insects, small mammals, and birds (Brown et al. 1979, p. 203). These animal species would also be the most likely vectors to disperse Lane Mountain milk-vetch seeds within and between populations. Sharifi (pers. comm. 2004) confirmed the presence of Lane Mountain milk-vetch seeds within native ant coppices (mounds). Seeds not consumed by granivores are buried beneath the plant litter and soil particulate accumulated by nurse shrubs that act as traps for wind-blown soil particles (Huggins et al. 2012, pp. 3–4). Wind and rain can mechanically bury seed through agitation of the soil (Huggins et al. 2012, p. 4).

Long-distance dispersal: Charlton (2007, p. 28) reported that Lane Mountain milk-vetch seed is scattered by strong winds that can occur in mid to late summer (Charlton 2007, p. 28). Detached seed pods with remaining seeds can disperse by wind or water several meters or more from their mother plant. Because of the relatively large size of the seed, dispersal to an adjacent population is probably rare, with seed dispersal across the four populations of Lane Mountain milk-vetch extremely rare (Huggins et al. 2012, p. 4) using wind or water as a dispersal vector.

This conclusion is supported by Walker and Metcalf’s (2008b) findings that there is limited gene flow between Lane Mountain milk-vetch populations (see Genetics section above). The higher shrub density in the mixed scrub vegetation community where the Lane Mountain milk-vetch occurs (see Habitat Characteristics, Associated Plant Community below) reduces inter-shrub distance between potential nurse shrubs, which would increase the potential for successful Lane Mountain milk-vetch seed dispersal, germination, and growth within this vegetation community. Reciprocally, the lower densities of potential nurse shrub species in creosote bush-dominated communities that occur between Lane Mountain milk-vetch populations may create inter-shrub distances too great to support Lane Mountain milk-vetch seed dispersal between populations, effectively blocking expansion of the species (Prigge et al. 2011, p. 185).

Seed bank: The seed bank of the Lane Mountain milk-vetch is composed of two components: (1) seeds produced in previous reproductive seasons that are to some extent buried in the soil beneath nurse shrubs (the persistent seed bank), and (2) new seeds, produced from the current reproductive season, that are superficially distributed on the soil surface after seed release (the transient seed bank) (Huggins et al. 2012a, p. 6). During wetter than normal years, substantial contributions to the seed bank may occur, while during dry years there may be little seed production and contribution to the seed bank. During the 2001 Army survey, Charlton (2007, p. 27) reported that field crews saw copious amounts of milk-vetch seed fall and build up at the base of the nurse shrub.

Huggins et al. (2012a, p. 7) collected data on pre-dispersal seed densities of the Lane Mountain milk-vetch in 2009, 2010, and 2011, and learned that the transient seed bank appears to be almost completely depleted before the next reproductive season. The mean density of the transient seed bank varied between zero and 700 seeds per 10.8 square ft (1.0 square m) between reproductive periods of June to March, while the persistent seed bank remained more or less constant at approximately 140 seeds per 10.8 square ft (1.0 square m). This means that the Lane Mountain milk-vetch persistent seed bank should be relatively insensitive to between-year variations in precipitation, because only a fraction of the transient seed bank is incorporated into the persistent seed bank each year Huggins et al. 2012a, p. 7). They also learned that years with high precipitation do not produce higher density transient seed banks than years with low precipitation. The lower density seed bank in years with high seed productivity was attributed to an increase in the consumption of seed by seed predator populations such as kangaroo rats, birds, and ants during the 5-week period in which seedpods were dehiscing (i.e., dropping their seeds) (Huggins et al. 2012a, pp. 7–8). In addition, in 2010 and 2011, there was early-season precipitation. Because of this, Lane Mountain milk-vetch experienced a 20 percent (one week) longer dehiscence period and resprouting. The early-season precipitation may have also contributed to the increase in seed predators that were observed during this time period. This increase in the period of dehiscing increased the time in which seeds were exposed to seed predators, which, together with the increase in seed predators, may have further reduced the post- dispersal, transient seed bank (Huggins et al. 2012a, p. 8). Upon analysis of inter-seasonal seed density, Huggins et al. (2012a. p.8) concluded that the decreases in seed density occurred in the summer, suggesting that seed consumption occurs primarily during this season, and the rates of seed consumption decline during the fall and winter, as the transient seed bank is depleted.

Seedling Growth, Survival, and Recruitment:

Growth: Little information has been collected on seedling growth in the wild. To supplement this limited information, Rundel et al. (2005) conducted greenhouse experiments. Rundel et al. (2005, p. 24) measured the growth of Lane Mountain milk-vetch seedlings for 45 weeks. They observed that seedlings maintain their cotyledon leaves for as long as 30–45 days without producing their first new leaf (Rundel et al. 2005, p. 18). The first leaflet was composed of three leaflets and subsequent leaves with more leaflets. Lane Mountain milk-vetch seedlings are readily recognizable because of their lunate (crescent-shaped) cotyledons (first leaves) and pinnately compound leaves (Rundel et al. 2005, p. 19).

Shoot growth of Lane Mountain milk-vetch during the early seedling stage was very slow. After seed germination, it took 4 to 6 weeks for the seedlings to reach 1.2 to 2 in (3 to 5 cm) in length (Rundel et al. 2005, p. 23). Rundel et al. (2005) concluded that Lane Mountain milk-vetch appears to allocate most of its initial photosynthetic carbon gain to root production (Rundel et al. 2005, p. 23). In the desert, a strategy of developing an extensive or deep root system would ensure that adequate water could be extracted from the soil when it begins to dry out. The results from measuring the canopy height of seedlings during the first 45 weeks showed that: 1) aboveground growth was slow, growing up to 2 in 3.5 cm) during the first 4 to 6 weeks, and 2) it increased the last 39 to 41 weeks, growing 32 in (81.3 cm), (Rundel et al. 2005, p. 23). At this height, the plant should be visible in the nurse shrub. At a study site within the Goldstone population, Huggins et al. (2012b, pp. 8–9) found that with supplemental watering to mimic a year with high precipitation, first-year seedlings did not flower, and many resprouting second- year seedlings did not flower with supplemental watering.

Survival: Recent studies in the field indicate that the Lane Mountain milk-vetch has low seedling survival and low recruitment (number of individuals surviving to reproduce) (Rundel et al. 2005; Rundel et al. 2007). A UCLA study on the Lane Mountain milk-vetch followed the development of seedlings in the field. During 1999 and 2000, Rundel et al. (2005, p. 12) found no Lane Mountain milk-vetch seedlings at the study plots in the Brinkman Wash-Montana Mine population, even though there was good seed production in 1999 and plots were checked several times during the year. In April 2003, Rundel et al. (2005) monitored 82 seedlings at the four long-term plots. By October 1, only six Lane Mountain milk-vetch seedlings were alive, and by spring 2004, all had perished. In winter of 2004–2005, during which there was record high precipitation, 14 Lane Mountain milk-vetch seedlings were tracked. Twelve survived the 2005 summer, and eight survived to the spring 2006.

Rundel et al. (2007) conducted greenhouse studies on the growth of seedling Lane Mountain milk-vetch plants. They found that summer rain is critical for seedlings establishment and survival to the next spring growing season (Rundel et al. 2007, p. 42). In addition, the amount, timing, and frequency of precipitation required for germination can be different from that required for seedling survival (Went 1949, p. 12). As a result, successful germination is sometimes followed by complete seedling mortality (Venable and Pake 1999, pp. 119–121). We conclude that the establishment of new Lane Mountain milk-vetch plants does not appear to occur with great frequency (Service 2010, p. 16406). This conclusion is supported by the work of Sharifi et al. (2010, p. 12) that indicates there was no recruitment of new Lane Mountain

milk-vetch from 1999 through 2009 in the permanent study plots at the Goldstone and Brinkman Wash Montana Mine populations.

Recruitment: The UCLA study examined recruitment of the Lane Mountain milk-vetch in the field. The researchers defined recruitment as the year of first flowering by a plant following germination. Of all seedlings surviving 1 year, none had reproduced (no flower production) (Rundel et al. 2007, p. 35). Several resprouted in year 2, a drier than normal year, but they did not flower. Thus, at least 2 consecutive wet years seem to be essential for seedlings to become established (Sharifi et al. 2010 pp. 15–16) and for first flowering to occur after the second year (Rundel et al. (2007, p. 35).

The UCLA research group (Huggins, Prigge, Rundel, and Sharifi) observed Lane Mountain milk-vetch seedlings from 1999 to 2011. At the four permanent 2.5-ac (1-ha) study plots in the Brinkman Wash-Montana Mine and Goldstone populations, Huggins et al. (2012b, p.129) reported that they observed recruitment of reproductive plants into the study plots 43 times between 2003 and 2011. Of these 43 recruits, 20 (47 percent) survived to 2011. Consequently, the total population of 30 live Lane Mountain milk-vetch plants in the study plots in 2011 consisted of 10 plants from the initial surveys in 1999 and 2003, and 20 plants recruited between 2003 and 2011. Lane Mountain milk-vetch recruitment has been relatively modest since 1999, even during an extraordinary wet season such as 2005 (13.9 in (35.2 cm)) (Huggins et al. 2012b, p. 2).

Huggins et al. (2011) also noted that large Lane Mountain milk-vetch plants had a high proportion of both multiple stems and woody bases. The large size, multiple stems, and woody bases likely increase the probability of resprouting (Huggins et al. 2011, p. 62). Thus, nurse shrubs with larger canopies are likely to produce larger Lane Mountain milk-vetch plants, and larger plant have a greater probability of resprouting in year 2 and subsequent years resulting in increased recruitment and longer-term survival of the Lane Mountain milk-vetch.

The Army recorded limited information on Lane Mountain milk-vetch seedlings during their 3-year transect surveys and 9-year permanent 50 m2 (164 ft2) study plots. They reported that less than 2 percent of the 4,888 individual Lane Mountain milk-vetch plants detected by the Army during transect surveys from 2000 to 2002 were recorded as seedlings (Charis 2002, p. 36). No information is available on how many of these seedlings survived to reproduce (recruitment). Within the Army’s 40 study plots, Hessing and Shaughnessy (2011, p. 37) identified 13 Lane Mountain milk-vetch seedlings in 2009, 26 in 2010, and 44 in 2011. Although Lane Mountain milk-vetch seedlings were found, no information is available on the number of seedlings that flowered (recruitment). Referring to the results from the UCLA’s focused studies on seedling survival and recruitment in permanent study plots from 1999 to 2011, most seedlings did not survive to the second year to flower (recruitment) (Huggins et al. 2010a, pp. 22–23; Huggins et al. 2011, p. 64; Huggins 2012 et al., p. 18).

Using data collected on observed population size, observed mortality, and weather data from four populations of the Lane Mountain milk-vetch, Rundel et al. (2005, p. 10) concluded that rain-year precipitation may need to be greater than 7 in (18 cm) to have seedling establishment. If correct, then, during the 19 years from the winter of 1990–91 to 2008–09, only

4 years or the winters of 1991–92, 1992–93, 1997–98, 2004–05 had rain year-precipitation greater than 7 in (18 cm) (Rundel et al. 2005, p. 11, Huggins et al. 2010, p. 122) and would have allowed for seedling establishment. The frequency and time of this precipitation likely influence the effectiveness of seedling establishment, growth, and survival (Rundel et al. 2005, p. 11). Rundel et al. (2007, p. 44) concluded that exceptionally above average and frequent precipitation is required for recruitment of Lane Mountain milk-vetch to occur. Such conditions are estimated to occur about once every 10 years in the range of the Lane Mountain milk-vetch based on past climatic patterns. In addition, Huggins et al. (2012b, p. 17) reported that recruitment has been relatively modest, even during an extraordinary wet year such as 2005. As a result, the frequency of population cycles (i.e., recruitment and mortality) should be lower or gradual in Lane Mountain milk-vetch rather than the “boom or bust” dynamics of the other xeric (drought- adapted) Astragalus species. The population cycles are in phase with wet and dry climate- periods in the Mojave Desert (the climate-period hypothesis) (Huggins et al. (2012b, p. 18).

Dormancy

Intra-annual Dormancy: Limited data are available on the duration of dormancy for the Lane Mountain milk-vetch. Although most or the entire aboveground portion of the plant dies back each year to a caudex in late spring or early summer, individual Lane Mountain milk-vetch plants may persist as a perennial taproot through the dry season. The caudex is a knotty root- crown composed of one or more stem-bases, which gives rise to new herbaceous growth each year. The location of the caudex in the Lane Mountain milk-vetch has been described by Barneby (1964) as buried below the soil surface 0.4 to 1.6 in (1 to 4 cm), at the soil surface (Blackmore and Tootill 1984), or 0.8 to 4.0 in (2.0 to 10.0 cm) above the soil surface (Huggins et al. 2011, pp. 18–19). Huggins et al. (2011, p. 19) reported that most or all of the Lane Mountain milk-vetch stems produced the previous season die back to the caudex, but every study plant had at least one, but as many as 5 stems that remained partially green from the previous season. These persistent green stems were as long as 15 in (38 cm). The presence of persistent green stems on dormant Lane Mountain milk-vetch plants has been previously noted by Bagley (1998) (Huggins et al. 2011, p. 19).

Careful investigation of the caudex during the year, especially after rain, can help determine whether a plant is dormant or dead. The exception is summer precipitation. Huggins et al. (2012, p. 9) reported that during their study, summer precipitation was never observed to result in germination of seed or breaking of dormancy of established plants.

Yearlong Dormancy: While the perennial root may allow the Lane Mountain milk-vetch to survive occasional dry years, it may endure longer periods of drought by remaining dormant. Therefore, determining whether an established Lane Mountain milk-vetch plant is dormant or dead is difficult unless the plant is tagged, carefully observed throughout the year, and tracked for a few years. Huggins et al. (2012b, p. 2) reported that during a 13-year study period (1999– 2011), dormancy (no aboveground growth in a given growing season) was a relatively uncommon phenomenon for the Lane Mountain milk-vetch based on data collected from four permanent study plots. Of 20 plants tracked, dormancy did not exceed 3 plants per year except during the drought year of 2007 when 19 of 20 plants remained dormant. Episodes of dormancy (1 season or 2 consecutive seasons) were observed 25 times in 22 different Lane Mountain milk-

vetch study plants between 1999 and 2011. Most episodes of dormancy (n = in 23 individuals) lasted a single season; two study plants had dormancies that lasted 2 consecutive seasons. Most study plants that experienced dormancy had a single episode of dormancy during the study period; three study plants had 2 single-year episodes of dormancy; both of these plants survived to 2011 (Huggins et al. 2012b, p. 13).

Longevity

We have some indication that individual Lane Mountain milk-vetch plants may have a long life span. In one long-term plot, individuals have been tracked for 13 years. Of 9 individuals studied, one had persisted for 13 years, one had persisted 12 years, one had persisted 10 years, one had persisted 6 years, one had persisted 5 years, and 2 had persisted 3 years (Rutherford in litt. 2009).

Of the 85 plants tracked since 1999 during the UCLA study, six plants survived to 2011, demonstrating that the life span of some Lane Mountain milk-vetch can be as long as 13 years (Huggins et al. 2012b pp. 11–12). One Lane Mountain milk-vetch plant tagged in 1993 survived to 2011, which suggests that the life span of the Lane Mountain milk-vetch may exceed 18 years (pers. comm. Connie Rutherford Service; as cited in Huggins et al. 2012b, p. 12).

Mortality

Hessing and Shaughnessy (2011) calculated mortality for the Lane Mountain milk-vetch from the 40 permanent study plots monitored by the Army during a 6-year period (2005 to 2011). From 2009 to 2010, Hessing and Shaughnessy (2011, p. 36) reported 6.3 percent mortality of Lane Mountain milk-vetch plants, while from 2010 to 2011, they reported 4 percent mortality (i.e., 5 of 151 Lane Mountain milk-vetch plants were confirmed dead). They also calculated cumulative mortality, the number of Lane Mountain milk-vetch plants that died after 1 year, after 2 years, etc., for 2005-2006, 2008-2009, 2009-2010, and 2010-2011. Data from 2007 were not used because most Lane Mountain milk-vetch plants were dormant (Huggins and Shaughnessy 2011, p. 32). The cumulative mortality of the Lane Mountain milk-vetch during a 2-year period was estimated as 13 percent; during a 5- and 6-year period it was 60 percent (Hessing and Shaughnessy 2011, p. 56). Using these data, Hessing and Shaughnessy (2011, p. 36) hypothesized that the average life expectancy of the Lane Mountain milk-vetch appears to be short for most new plants.

The amount and frequency of precipitation are important factors regarding the mortality of the Lane Mountain milk-vetch. Mortality for plants established during two consecutive dry years was more than 63 percent, while plants established during a wet year had a mortality of 60 percent after 7 years (Hessing and Shaughnessy 2011, p. 36).

At the UCLA study sites, Huggins et al. (2010a, pp. 122–123) reported 100 percent mortality of Lane Mountain milk-vetch seedlings in the study plots since surveys began in 1999 at the Brinkman Wash-Montana Mine population, and since 2003 at the Goldstone population. Lane Mountain milk-vetch mortality of mature plants, though higher in drought years such as 2007 (0.7 in (19 mm)), has been more or less gradual (Huggins et al. 2012b, p. 17) rather than in

pulses, and occurs in phase with wet and dry climate periods in the Mojave Desert (climate- period hypothesis) (Huggins et al. 2012b, p. 2). This gradual pattern in the frequency and amplitude of Lane Mountain milk-vetch population cycles is supported by the continued mortality of mature Lane Mountain milk-vetch plants in an unusually wet year like 2005 (Huggins et al. 2010a, p. 126).

Predation

There is little information available on predation of Lane Mountain milk-vetch plants, including no available studies of the predation by animals on the Lane Mountain milk-vetch. Rather, information on predation has been observational or presumptive and incidental to the purpose of the study. Hopkins (2005a) observed predation on one plant by numerous aphids and predation of fruits on one plant by hemipterans or true bugs (Hopkins 2005a, pp. 2 and 6). Charlton (2007, p. 27) assumed that jackrabbits (Lepus californicus) or rodents ate some of the dried skeletons of Lane Mountain milk-vetch plants because most of the skeletons observed in 2002 were gone in 2003 and they were too intertwined in the nurse shrubs to break off and blow away. Rutherford (2005 in litt., p. 1) photographed rodent or lagomorph predation on Lane Mountain milk-vetch plants at the Coolgardie Mesa population when the plants were beginning to bloom.

Rundel et al. (2007, p. 43) reported predation on Lane Mountain milk-vetch plants for the years 2003, 2005, and 2006, respectively: at the Goldstone plots, Rundel et al. reported 3, 36, and 28 percent of the plants were browsed, and at the Brinkman Wash-Montana Mine plots, 0, 27 and 24 percent of the plants were browsed. They noted that the high productivity of annual plants in winter 2004-2005 also promoted the growth of the jackrabbit population, which had a negative impact on both mature and seedling Lane Mountain milk-vetch plants in 2005 (Rundel et al. 2007, p. 434). While predation of the vegetative portions of the Lane Mountain milk-vetch plant may not kill the plant, it reduces the size of the plant. Recall that plant size is strongly correlated with seed production (Huggins et al. 2011, p. 36) (see Fruit and Seed Production, Germination, and Viability – Production). Thus, predation likely reduces reproductive effort including flower and seed production.

Habitat Characteristics

Lane Mountain milk-vetch occurs in specific habitats in the transition zone between creosote bush scrub and Joshua tree woodland (Prigge et al. 2000, p. 9) and in mixed desert scrub (Charis 2002, p. 38) vegetation communities in the Mojave Desert. To understand more about the environment in which the Lane Mountain milk-vetch must survive, we are providing information on the environmental setting of the Mojave Desert and the area of the Mojave Desert in which the species occurs.

Location and Topography

The Mojave Desert is bound on the western end by the Tehachapi, San Gabriel, and San Bernardino mountain ranges. It extends east into southern Nevada and northwestern Arizona. Elevations are mostly above 2,000 ft (609 m), which is in contrast to the lower elevation Sonoran (Colorado) Desert along its southern boundary in California (Michaelsen 2013 http://www.geog.ucsb.edu/~joel/g148_f09/readings/mojave/mojave_desert.html).

The Mojave Desert in California can be divided into three subregions that have indistinct boundaries, but the subregions are rather different. These subregions are the western Mojave subregion (the Antelope Valley), the central Mojave subregion (includes the Mojave River Valley area from Victorville to Baker and south to Joshua Tree National Park), and the eastern Mojave subregion (between I-40 and I-15 in the eastern portion of Mojave National Preserve). Its edges blend indistinctly into the Basin and Range region to the north and the Colorado Desert region to the south (Michaelsen 2013 http://www.geog.ucsb.edu/~joel/g148_f09/readings/mojave/mojave_desert.html).

The distribution of Lane Mountain milk-vetch is restricted to a small area in the central subregion of the Mojave Desert. Most individuals occur between 3,365 ft (1,026 m) and 3,854 ft (1,175 m) in elevation (Charis 2003b, p. 11). The four populations occur between longitude - 116.4610 on the east, -117.0240 on the west, and latitude 35.1450 to the north, and 35.0310 to the south (Service 2013a, p.1).

The central Mojave subregion is an area of broad valleys and scattered, isolated mountain blocks that are mostly lower than 6,560 ft (2,000 m). The elevations of the valley floors range from about 984 ft (300 m) to more than 3,280 ft (1,000 m) in the Joshua Tree National Park region. The valleys are mostly interior drainage, although the Mojave River does create a larger, somewhat connected drainage basin for part of the subregion. There is evidence of relatively recent (that is, about 10,000 years ago near the end of the most recent ice age [,http://digital- desert.com/cinder-cones/; accessed 2013-12-6]) ) volcanic activity in the area, which has produced scattered lava flows deposits and cinder cones (Michaelsen 2013 http://www.geog.ucsb.edu/~joel/g148_f09/readings/mojave/mojave_desert.html).

Climate

Temperature: The Mojave Desert has a temperate climate, experiencing hot temperatures in the summer, and sub-freezing temperatures in the winter. Mean monthly temperatures range from a low of 46 degrees Fahrenheit (ºF) (7.8 degrees Celsius (ºC)) in December and January to 88 ºF (31.1 ºC) in July (Pavlik 2008, p. 73). Great diurnal variation also exists, sometimes as much as 40 º F (4.4 ºC) (Kahn 2006, pp. 6–8).

Temperatures in the Mojave Desert are influenced by elevation. Summer daily maximum temperatures range from about 111 ºF (44 ºC) at Baker (elevation 951 ft or 290 m) in the central Mojave subregion to about 86 degrees F (30 ºC) above 4,921 ft (1,500 m) in the eastern Mojave subregion. Winter nighttime minimum temperatures show less variation, ranging from 39 ºF (4

ºC) at the low elevations to 23 ºF (–5 ºC) at the higher elevations (Michaelsen 2013 http://www.geog.ucsb.edu/~joel/g148_f09/readings/mojave/mojave_desert.html).

Latitude also plays a role in determining temperature. The Mojave Desert is north of the Sonoran Desert and its average elevations are higher. As a result, its average temperatures are lower than those of the Sonoran Desert. When compared to the Great Basin Desert, the average temperatures in the Mojave Desert are warmer because of lower average altitude and lower latitude (Mojave Desert Climate 2001, entire; Kahn 2006, p. 6).

In the central subregion of the Mojave Desert, mean temperatures in the Barstow area near the distribution of the Lane Mountain milk-vetch are: in January the maximum is 60.0 ºF (15.6 ºC), minimum is 31.7 ºF (-0.17 ºC), and mean is 45.9 ºF (7.7 ºC); in July the maximum is 102.6 ºF (39.2 ºC), the minimum is 67.2 ºF (19.6 ºC), and the mean is 84.2 ºF (29.0 ºC) (http://pubs.usgs.gov/of/2004/1007/weather.html).

Humidity: The desert air mass, regardless of temperature, contains little water vapor (humidity). It quickly absorbs any moisture it contacts (e.g., soil surface, plant leaves, animal lungs) (Pavlik 2008, p. 72). The strong evaporative power of the atmosphere in relation to the amount of water falling as precipitation is embodied in the evapotranspiration-to-precipitation ratio (ET/P). By this measure, a true desert has an average ET/P range of 5 to 33, which means that the air has the power to evaporate from 5 to 33 times more water than falls as precipitation (Pavlik 2008, p. 72). The Mojave Desert has an average ET/P range of 3 to 33 (Pavlik 2008, p. 69).

Wind: The Mojave Desert is a wind machine. Lack of clouds permits more solar energy to fall upon the desert soil and heat the desert air. The hot desert air rises and leaves behind a low-pressure sink into which cool air flows from other parts of the state (Pavlik 2008, pp. 76– 77). Although it is windy during all months, wind is a prominent feature in late winter and early spring, with dry winds blowing in the afternoon and evening. Winds in excess of 25 mph (40 kph), with gusts of 75 mph (121 kph) or more are not uncommon. November, December, and January are generally the calmest months (Mojave Desert Climate 2001, entire). In the area north of Barstow, the location of the four Lane Mountain milk-vetch populations, the prevailing wind direction is to the east or to the south-southwest (Reheis 2006, p. 489).

Precipitation: The mountains that form the western boundaries of the Mojave Desert cause an orographic effect to precipitation; they remove moisture from storms approaching from the Pacific Ocean to the west or windward side, resulting in a drier climate on the leeward or east side. Drier air is left on the descending, generally warming, leeward side where a rain shadow is formed.

The mean annual precipitation in the Mojave Desert is 5.0 in (12.7 cm) (http://www.blueplanetbiomes.org/mojave_climate.htm [accessed 2013-9-24]). Rainfall in the winter season (October to May) averages 3.7 in (9.5 cm), whereas rainfall in the summer season (June to September) averages 1.4 in (3.5 cm) (Hereford et al. 2004, pp. 1–4; Kahn 2006, pp. 6– 8). One exception is the mountains of the eastern Mojave subregion where precipitation totals are 11.8 in at 4,265 ft (30.0 cm at 1,300 m) and presumably more at higher elevations where

there are no measuring stations (Michaelsen 2013, entire). In comparison, the mean precipitation in Barstow near the distribution of the Lane Mountain milk-vetch is 4.14 in (10.5 cm) (USGS 2004 http://pubs.usgs.gov/of/2004/1007/weather.html).

There is a substantial change in the seasonal distribution of precipitation moving west to east across the Mojave Desert. In the western subregion of the Mojave Desert, most of the precipitation comes in winter (October to May) from large frontal cyclonic storms that move east out of the Pacific (Bullock 2003). The storms originate from the Gulf of Alaska and near the Hawaiian Islands (Kahn 2006, p. 15). About 90 percent of the annual average precipitation is from these winter storms, while less than 10 percent occurs in summer. In the central Mojave subregion, summer rainfall contributes more to the annual total. In the eastern Mojave subregion, a substantial percent of the annual precipitation total comes in summer thunderstorms. The summer season experiences precipitation in the form of local convective storms, which form as a product of the North American Monsoon and as remnants of hurricanes off Baja California. The former is a period of pronounced rainfall between July and September powered by the warm waters of the Gulf of Mexico and thermal heat flows that form above the surface during summer months in the southwestern United States (Comrie and Broyles 2002; 573–592; Kahn 2006, pp. 6–8). This produces a flow of warm, humid sub-tropical air that moves north from Mexico into the southwestern United States during mid and late summer. In the eastern Mojave subregion, the two seasons may be almost equal in precipitation amounts (Michaelsen 2013 http://www.geog.ucsb.edu/~joel/g148_f09/readings/mojave/mojave_desert.html).

Means of air temperature, ET/P, and annual precipitation are not adequate to characterize desert climates and understand their effects on plants and animals. The timing, occurrence of stressful extremes, and uncertainty are crucial and more difficult to measure, and are probably the back-breaking straws for many desert species (Pavlik 2008, p. 73). The plant or animal best equipped for parching drought, searing air, or hard frost can be tested by the uncertainty that accompanies these extremes. This uncertainty makes biological tolerance mechanisms of desert- adapted species less effective and creates unpredictable patterns of persistence of species through time (Pavlik 2008, p. 73).

Historically, rainfall in the Mojave Desert has been variable on both short and long-term time scales. This variability has been linked to events in the Pacific Ocean. The short-term time scales are related to the Southern Oscillation Index (SOI) and equatorial water temperatures. El Ninõ and La Ninã are the resulting episodes that are opposite extremes and occur every 3 to 5 years. Warm sea surface temperatures (SST) and a negative SOI indicate an El Ninõ episode, which increases rainfall in the southwestern United States. Cold SST and a positive SOI indicate a La Ninã event, decreasing rainfall in the southwestern United States including the Mojave Desert (Climate Prediction Center).

Long-term climatic variations are related to the Pacific Decadal Oscillation (PDO). In the past variations in the Pacific Ocean SST caused cycles of dry and wet periods in the southwestern United States about every two to three decades. Cool SSTs indicate a dry spell and warm SSTs indicate a wet spell (Hereford et al. 2004; pp. 1–4; Kahn 2006, pp. 6–8).

During the last few decades, precipitation in the Mojave Desert and the Barstow area near the distribution of the Lane Mountain milk-vetch has varied. From 1942 to 1976, the precipitation recorded in the Mojave Desert was drier than normal. This was followed by a wetter than normal period from about 1978 to 1998 (Hereford and Longpre (no date), Range of Precipitation http://mojave.usgs.gov/climate-history/), and a drier than normal period from 1999 to the present (Huggins et al. 2012b, p. 6). During this wet period, the mean precipitation during the growing season (October through May) from rain gauges in the Barstow area near the distribution of the Lane Mountain milk-vetch was 5.04 in (128 mm); from 1999 to 2011, the mean precipitation was 4.41 in (112 mm) (Huggins et al. 2012b, p. 26). This is a 0.63-in (16.0- mm) decline in mean precipitation between the wet period and dry period. From 1999 to 2011, precipitation during the growing season varied from a high of more than 9.8 in (250 mm) in 2004–2005, to less than 1 in (25 mm) in 2001–2002 and 2006–2007 (Huggins et al. 2012b, p. 26). From 1999 to 2011 (i.e., fall 1999 to spring 2012), there were two periods of drought (i.e., 2 or more consecutive years with precipitation amounts below the mean); the first was from fall 1999 through spring 2003 and the second was from fall 2006 through spring 2010 (Huggins et al. 2012b, pp. 10, 26). Recent data indicate that dry and wet climate periods in the Mojave Desert cycle every 20 to 30 years, and so recent series of drought conditions may represent the onset of a new dry climate period (Hereford et al. 2006, pp. 23–30).

Soils and topography

Lane Mountain milk-vetch appears to prefer a specific soil type. Bagley (1999, p. 3) reported that the Lane Mountain milk-vetch appears to be confined to granitic substrates. It occurs on gentle slopes and low ridges, only a foot or two higher than the main bajadas slope, and rocky low hills, 10 to 20 ft (3.01 to 6.1 m) high (Lee and Ro Consulting Engineers, 1985, Chapter 2, p. 12; Charis 2002, p. 40). Rundel et al. (2005, p. 34) reported that Lane Mountain milk-vetch habitat differs from surrounding sites in that the granitic parent rock is very close to the soil surface and is commonly exposed, and soils are more shallow and composed of coarser, decomposed granite.

Several species of Astragalus are known to be selenium accumulators and are restricted to selenium substrates. Edaphically restricted plants (plants restricted to soil types or textures) are generally poor competitors off the substrate that they are adapted to and only compete well on that type of substrate. Sharifi et al. (2007, p. 2) did not find any selenium in soil samples (unpublished data) that could explain the limited distribution of the Lane Mountain milk-vetch. However, the greater presence of the species on shallow ridges where soils are thinner and bedrock much closer to the surface, as opposed to deeper alluvial soils, suggests that occupied sites have a better moisture supply (Charis 2002, p. 10) and Lane Mountain milk-vetch may have a greater moisture requirement than other desert perennial species. Huggins et al. (2012b, pp. 4– 5) noted that because Lane Mountain milk-vetch is restricted to patches of shallow-soiled habitat where the density of creosote bush is reduced, and the density of compatible nurse shrubs is high, the species appears to be a novel example of a second-order edaphic endemic (its distribution is indirectly controlled by edaphics through the effect of edaphics on its community of nurse shrubs) (Prigge et al. 2011, p. 185; Huggins et al. 2012b, p. 4)).

Associated plant community

The vegetation community at Lane Mountain milk-vetch sites is typically a diverse mix of shrub species including California buckwheat (Eriogonum fasciculatum ssp. polifolium), Nevada Mormon tea (Ephedra nevadensis), Cooper goldenbush (Ericameria cooperi), turpentine-broom (Thamnosma montana), paper-bagbush (Salazaria mexicana), Mojave aster (Xylorhiza tortifolia), hop-sage (Grayia spinosa), Anderson box-thorn (Lycium andersonii), creosote bush, and burrobush (Ambrosia dumosa). This mixed desert scrub vegetation where Lane Mountain milk-vetch occurs has a higher diversity of perennial woody species and higher percent cover and density than adjacent vegetation communities including creosote bush dominant communities that do not support Lane Mountain milk-vetch (Prigge et al. 2000, p. 10; Prigge et al. 2011, p. 185). These perennial woody species not only comprise important components in the associated plant community, but many also have a specific relationship with Lane Mountain milk-vetch, which is discussed below. Creosote bush and burro bush are dominant woody perennial species on the surrounding sandy bajada slopes, but are not dominant woody shrub species on the thin soils where the Lane Mountain milk-vetch occur (Bagley 1989, as cited in Bagley 1999, p. 3; Brandt et al., 1997, p. 7).

Nurse shrubs and influence on microclimate and microhabitat of Lane Mountain milk-vetch

The relationship between the Lane Mountain milk-vetch and its nurse shrub may be more than providing structural support. Examination of this relationship indicates that there is a nurse- protégé interaction between the shrub and Lane Mountain milk-vetch. Harsh conditions in the Mojave Desert make seedling establishment rare for desert plant species. Plant recruitment often is limited to years with above average rainfall and/or in safe sites under the canopy of nurse plants that provide shelter from high temperatures and low moisture. Associations of establishing seedlings with different species of mature plants are referred to as nurse-protégé interactions (Flores and Jerado 2009, p. 911). Several studies have demonstrated that the shade produced by nurse plant canopies mitigates severe temperature and moisture conditions in a desert environment by reducing air and soil temperature (Franco and Nobel 1989, p. 884; Valient-Banuet et al. 1991, p. 18; Paez and Marco 2000, p. 65; Flores et al. 2004, p. 14), and increasing soil moisture availability (Nolasco et al. 1997, pp. 127–128; Shumway 2000, p. 145; Huggins et al. 2010, pp. 124–125). Facilitation by the nurse shrub occurs when microclimate effects such as these increase the establishment and survival of protégé plants growing under nurse shrub canopies (Cody 1993, pp. 139–154).

Sharifi et al. (2010) studied this nurse-protégé relationship for the Lane Mountain milk- vetch. They found that soil surface temperature and light intensity beneath shrubs depended on the condition of the shrub’s canopy. Shrubs with open canopies have light levels five times higher than shrubs with closed canopies, and soil surface temperature beneath shrubs with open canopies can be 35 ºF (19.5 ºC) higher than shrubs with closed canopies. Thus, the canopy condition of shrubs affects the microclimate beneath and within these shrubs, which also affects Lane Mountain milk-vetch plants (Sharifi et al. 2010, p. 12). More than 99 percent of mature (able to reproduce) Lane Mountain milk-vetch plants have been found growing from the base of nurse shrubs.

Although Lane Mountain milk-vetch has been observed using 30 different species of nurse shrubs that are small woody shrubs with heights less than 11.8 in (30.0 cm) (Huggins et al. 2012, p. 35), six species of shrubs comprised about 75 percent of the records (Charis 2002, p. 41). During one study, one-fifth of Lane Mountain milk-vetch plants were found in turpentine broom (Thamnosma montana) (Charlton 2007, p. 27). In another study, researchers concluded that Lane Mountain milk-vetch does not have a species preference for a nurse shrub because the frequency spectrum of nurse shrubs was proportional to the species cover of shrubs with trellis characteristics at a site in mixed scrub vegetation, with the exception of creosote bush (Prigge et al. 2011, pp. 178 and 181). Prigge et al. (2011, p. 185) reported that creosote bush is significantly under-represented as a nurse shrub when compared to its abundance in the vegetation community. Sharifi et al. (2010, p. 17) demonstrated that shrub canopy integrity has a significant effect on the microclimate beneath shrub canopies, and that shrubs with active Lane Mountain milk-vetch have more intact canopies than shrubs without active Lane Mountain milk- vetch. These finding explain the preference of Lane Mountain milk-vetch to occur in association with closed canopy shrub species such as turpentine bush and California buckwheat where air and soil temperatures are lower rather than open canopy shrubs such as creosote bush, where they are higher.

Nurse shrubs appear to be important to the survival and persistence of the Lane Mountain milk-vetch. Huggins et al. (2010a, pp. 20128) reported that a loss of 60 percent or more canopy cover of a nurse shrub results in the dead of the Lane Mountain milk-vetch plant.

Sharifi et al. (2009, p. 6) expanded the function of this nurse-protégé interaction to include protection from wind. Open shrub canopies (e.g., creosote bush) are less likely to protect seedlings from drying and potentially abrasive winds than closed shrub canopies (Charis 2002, p. 49). Regarding microhabitat conditions, Gibson et al. (1998, p. 81) postulated that Lane Mountain milk-vetch may have a mutually beneficial relationship with the nurse shrub. The shrub provides support for the milk-vetch, and Lane Mountain milk-vetch provides higher levels of soil nitrogen derived from the litter and roots of the Lane Mountain milk-vetch to the shrub (members of the pea family contain root nodules formed by soil bacteria which are capable of fixing nitrogen otherwise mostly unavailable to other plants) (Salisbury and Ross 1985, pp. 252– 254). Desert soils are low in bioavailable forms of nitrogen (McCalley and Sparks 2009, p. 837). Because the roots of Lane Mountain milk-vetch contain nodules that fix nitrogen, sites with Lane Mountain milk-vetch plants have higher nitrogen soil content (Gibson et al. 1998, pp. 80–81). In addition, Lane Mountain milk-vetch has significantly higher tissue nitrogen than its nurse shrubs (3.0 percent vs. 1.8 percent nitrogen content) (Sharifi et al. 2009a, p. 321). When a Lane Mountain milk-vetch plant dies back every year, its tissue decomposes and enriches the soil below it with nitrogen, thus enriching the soil of the nurse shrub.

Sharifi et al. (2009, pp. 5–6) reported that the nurse shrub together with the Lane Mountain milk-vetch establish “fertile islands” at the base of the shrub that contain significantly higher organic matter and nutrients than surrounding areas. The nurse shrub traps organic matter carried by wind. Organic matter is deposited at the base of the shrub and accumulates over time (Garcia-Moya and McKell 1970, p. 86). The nurse shrub also drops the leaves, flowers, and fruits (plant litter) it produces (Huggins et al. 2012, p. 4). We assume that a shrub with a dense canopy would be able to trap and deposit more organic matter than one with an open canopy (e.g., creosote bush). In addition, dense shrub canopies may provide protection to Lane Mountain milk-vetch from herbivory (Gibson et al. 1998, pp. 81–82), at least from jackrabbits (Sharifi et al. 2009a, p. 6).

This nurse-protégé interaction also means that the nurse shrub shares water resources with Lane Mountain milk-vetch, but the degree to which they compete when water resources are limited is unknown (Huggins et al 2010, p. 120). This implies that the relationship between the Lane Mountain milk-vetch and its nurse shrub may also be antagonistic to some degree (Huggins et al. 2010, p. 120).

There may be another reason that Lane Mountain milk-vetch occurs in this mixed scrub vegetation community. Prigge et al. (2011, p. 185) reported that the higher shrub density in this vegetation community has reduced distances between shrubs including potential nurse shrubs. These reduced distances may help increase Lane Mountain milk-vetch dispersal and population growth. Reciprocally, low nurse shrub densities in adjacent creosote bush-dominated communities could create inter-shrub distances too great to support Lane Mountain milk-vetch dispersal, effectively blocking expansion of the species into these areas.

In summary, Lane Mountain milk-vetch occurs in specific granitic soil and vegetation types and likely exhibit second order edaphic endemism. These soil and vegetation types are limited, and appear to influence the distribution of the Lane Mountain milk-vetch. Within this limited distribution, the Lane Mountain milk-vetch has a patchy distribution (Charis 2002, p. 35). Nurse shrubs appear to be important to the survival and persistence of Lane Mountain milk-vetch plants. They provide a modified microclimate and microhabitat that lessens the harsh environmental conditions in the Mojave Desert, making the environment more conducive to growth, recruitment, and survival of Lane Mountain milk-vetch plants than in the open spaces between shrubs (Charis 2002, p. 49) or shrubs with open canopies.

Distribution

The precise locations of the first collections made by Jaeger, Barneby, and Munz from 1939 to 1941 are unknown, as collection information from that era were either vague (e.g. “13 mi north of Barstow”) or tied to unlocatable landmarks (“2 mi south of Jay Mine”) (Consortium of California Herbaria 2013). No further collections of this species were recorded until 1985 when the expansion of Fort Irwin was first proposed and the Army sponsored botanical surveys (Lee and Ro Consulting 1986). During the next 10 years, searches for this species resulted in locating few Lane Mountain milk-vetch plants.

At the time of listing in 1998, about 950 Lane Mountain milk-vetch plants were known from four general areas in a portion of the western Mojave Desert northeast of Barstow, San Bernardino County, California (63 FR 53596; October 6, 1998). Charis (2002, p. 13) referred to the four general areas or populations of the Lane Mountain milk-vetch known in 1999 as Coolgardie Mesa, Paradise Valley, Montana Mine, and Brinkman Wash (see Figure 3).

Following listing, the Army completed an extensive 3-year survey and a GIS analysis of potential habitat within 50 mi (80 km) of the known populations of the Lane Mountain milk- vetch (Charlton 2007, pp. 25–26). From this analysis of elevation, soils and geology (Charlton 2007, p. 30), the Army delineated and surveyed 387 transects in areas represented on twelve 7.5 minute U.S. Geological Survey quadrangle maps with potential habitat for the species. These included areas extending beyond the current known range of the Lane Mountain milk-vetch, from the west side of Coyote Lake Basin and East of Goldstone in the east to Harper Lake and Blackwater Well in the west and areas on the Mojave B Range of China Lake Naval Air Weapons Station to the northwest (Charis 2002, p. 17). The survey area included much of the granitic areas with gentle to moderate slopes, as this was identified as the substrate on which Lane Mountain milk-vetch usually were found (Charis 2002, p. 35) (see Habitat Characteristics).

The results of the 3-year survey were: (1) The Lane Mountain milk-vetch is restricted to four geographical areas; (2) nearly 4,000 plants were found within a 21,000 ac (8,500 ha) area; (3) population boundaries were delineated (Charis 2002, p. 18); (4) most Lane Mountain milk- vetch populations are located on lands managed by the Army or BLM; (5) the Lane Mountain milk-vetch has specific soil, topography, and elevation requirements (Charlton 2007, p. 24); and (6) the Lane Mountain milk-vetch does not occur in all locations where there is excellent potential habitat as determined using elevation, geology, and soils (Charlton 2007, p. 30). Thus,

substrate and slope are not the only factor limiting the patchy distribution of the Lane Mountain milk-vetch to the area north to northeast of Barstow to Goldstone in the western Mojave Desert. Based on this study, the entire known range of Lane Mountain milk-vetch is within the western Mojave Desert between Goldstone and Barstow, San Bernardino County.

The four geographical areas identified from the Lane Mountain milk-vetch survey results were an expansion of results previously reported by Prigge et al. (2000, p. 1). They identified four populations of Lane Mountain milk-vetch – Coolgardie, Paradise, Brinkman Wash, and Montana Mine. The Goldstone population was unknown at that time. Following the Army’s extensive surveys in 2001 and 2002, Charis (2002, p. 33) reported that the Montana Mine and Brinkman Wash populations were one continuous population and a fourth population, Goldstone, was discovered at the northeastern extent of the species’ range. Walker and Metcalf’s genetics research (see Genetics above) supports Charis’s findings that there are four populations, with the Coolgardie population containing the greatest genetic diversity of the four populations (Walker and Metcalf 2008b, p. 165). The Coolgardie Mesa population is comprised of two subpopulations, the Lane Mountain subpopulation occurring east of Copper City Road, and the Coolgardie subpopulation located west of this road. Because the two subpopulations are contiguous with each other at the northern and southern extent of their distributions, we continue to refer to the Lane Mountain and Coolgardie subpopulations collectively as the Coolgardie Mesa population. The two subpopulations are separated by an area about 0.6 mi (1 km) of an expanse of unoccupied habitat within the center of the Coolgardie Mesa, about 0.6 mi (1.0 km) wide that comprises less suitable habitat consisting of deep alluvial soils and creosote bush (Walker and Metcalf 2008b, p. 160). We refer to the four populations of the Lane Mountain milk-vetch as Coolgardie Mesa, Paradise Valley, Brinkman Wash-Montana Mine, and Goldstone. These populations are arrayed more or less linearly along a southwest to northeast axis.

The outer boundaries of the four populations of Lane Mountain milk-vetch comprise about 21,400 ac (8,660 ha) and are aligned along a 13-mi-long (30-km-long) axis (BLM et al. 2005, Chapter 3, p. 189. To facilitate conservation planning and land management in this portion of the Mojave Desert, population boundaries were determined by mapping every known occurrence of Lane Mountain milk-vetch through 2001, drawing lines to connect peripheral plant observations thereby creating one polygon for each of the four populations (i.e., minimum convex polygon). The four population polygons were surrounded with a 98-ft (30 m) buffer to account for the error in plant locality data from the Geographic Positioning System used by the Army (Charis 2002, pp. 28–29) (see Figure 1). Geographic positioning systems are not precise in mapping specific locations; the system used by the Army could be “off'” by up to 98 ft (30 m); placing a buffer around the mapped Lane Mountain milk-vetch locations ensured that all plant locations were included in the polygon. The area within these four polygons found during surveys in 1999, 2000, and 2001 for each of the four populations (rounded to the nearest 10 ac (4.0 ha)), are shown in Table 2 below (from Charis Corporation 2002).

Figure 3. Location of Lane Mountain Milk‐vetch Populations.

This method of determining areal extent includes areas in the population polygon that do not have Lane Mountain milk-vetch present. The closest distance between these population polygons currently is 1.0 km (0.6 mi) between Goldstone and Brinkman Wash-Montana Mine followed by 2.3 km (1.4 mi) between the Brinkman Wash-Montana Mine and West Paradise polygons and 5.0 km (3.1 mi) between the Coolgardie Mesa and West Paradise polygons (Service 2013b ). However, the closest distance between plants in each population is farther. Charis (2002, p. 35) reported that Lane Mountain milk-vetch plants in some portions of the populations occurred as widely scattered individuals, but for the most part the plants had a patchy distribution within the populations. Rundel et al. (2005, p. 9) reported similar findings with Lane Mountain milk-vetch plants occur in clusters of small, fragmented subpopulations (Rundel et al. 2005, p.9). Charis (2002, p. 35) hypothesized that this was due to the restricted habitat requirements of the Lane Mountain milk-vetch and the patchiness of the environment (see Habitat Characteristics).

The results of these extensive surveys clarified the distribution of the Lane Mountain

milk-vetch as known at that time. Its distribution is site specific and occurs only in a few disjunct sites (Charis 2002, pp. 33 and 35). These sites are within a 13.5 mi2 (35km2) area that extends from the southwestern portion of the Fort Irwin National Training Center (NTC) to Coolgardie Mesa and the southwestern slope of Lane Mountain. This area includes portions of Brinkman Wash, the north slopes of the Paradise Range, the northeastern slopes of Lane Mountain, and a region south of Montana Mine (Rundel et al. 2005, p. 8). The Lane Mountain milk-vetch occurs on moderate slopes and ridges with shallow decomposed granitic soil, avoiding the neighboring substrates of alluvial fans and slopes of sedimentary rocks. Within these areas, the Lane Mountain milk-vetch forms clusters of small, fragmented subpopulations (Rundel et al. 2005, pp. 8–9).

Table 2. Population size of the four Lane Mountain milk‐vetch populations by area (polygon) based on survey results through 2001 (from Charis 2002, p. 34).

Percent of Total Number of Polygon Size in Acres Population Area of Polygons Individual Plants (Hectares)1 Located Goldstone 1,283 (519) 6 555

Brinkman Wash- 5,498 (2,225) 26 1,487 Montana Mine

Paradise Valley 4,794 (1,940) 22 1,667

Coolgardie Mesa 9,775 (3,956) 46 2,014

Total 21,349 (8,640) 100 5,723 1 Includes a 98‐ft (30 m) buffer around the minimum convex polygon method for determining area.

Until recently, the distribution of Lane Mountain milk-vetch occurred on Federal and private lands. The Lane Mountain milk-vetch is found on lands managed by the BLM, the Army (on Fort Irwin and the National Training Center and the Goldstone Deep Space Communications

Complex), and on private land (BLM et al. 2005, Chapter 3, p. 189). The Goldstone and Brinkman Wash-Montana Mine populations are entirely on Army lands within the Fort Irwin boundary, and most of the Paradise Valley population is on Army lands at Fort Irwin. A small portion of the Paradise Valley population and most of the Coolgardie Mesa population occur on lands managed by the BLM. Numerous parcels of private lands were scattered among the area of the Coolgardie Mesa population and western portion of the Paradise Valley population. In 2005, the Army began acquiring private lands in the areas of these two populations and recently completed the acquisition of these parcels. Water and mineral rights were not acquired. The Army currently retains ownership of these parcels (Everly 2012 in litt. 2012-8-8 Email).

Abundance

Due to the cryptic nature of the species during the early part of the growing season and dormancy, it is difficult to detect the Lane Mountain milk-vetch during part of the year. This characteristic plus limited survey efforts contributed to only several hundred individuals having been located at the time the species was listed in 1998 (63 FR 53596). Bagley (1999, p. 6) reported that between 1985 and 1998 about 175 plants had been reported from casual survey efforts by botanists. With extensive surveys by the Army in 1999, 2000, and 2001 to document the entire range of the Lane Mountain milk-vetch (Charis 2002, p. 33), surveyors were able to locate more individuals (see Table 2). Different transect methods were used with survey efforts concentrated in known occupied habitat and other areas believed to be suitable habitat (potential habitat) for the Lane Mountain milk-vetch (Charis 2002, pp. 18–21). The survey efforts covered 17,000 ac (6,880 ha), and resulted in a slightly larger range being described for the Lane Mountain milk-vetch than previously known with about 5,000 plants recorded during this effort and surveys conducted by UCLA (Charis 2002 p. 37) (See Table 2). During this survey, the largest number of plants found in one day occurred while counting only skeletons of the plants (Charlton 2007, p. 30).

The wet period from 1976 to 1998 is presumed to have contributed to the largest number of Lane Mountain milk-vetch populations ever observed, which was in 1999 (Huggins et al. 2011, p. 9). During the Army’s survey effort, individual plants were not tagged (Hessing 2010, p. 2). The final report on survey results did not include an analysis of the data to estimate population size or abundance. Because the known area of occurrence for the Lane Mountain milk-vetch was sampled and not censused, the total number of individuals in the populations may have been greater than the individual number reported, assuming no mortality or recruitment occurred between 1999 and 2001 and plants were not double-counted. However, the actual number may not be that much greater, as transects were located in areas with potential habitat and where Lane Mountain milk-vetch plants had previously been found. They were not randomly placed. Given the patchy distribution of the habitat (low ridges with granitic soils), patchy distribution of the plants within the habitat, and biased survey method, the density/distribution of the Lane Mountain milk-vetch in surveyed areas is likely greater than the non-surveyed areas within the polygons delineating the four populations of the Lane Mountain milk-vetch.

Demography and Population Trends

Although Lane Mountain milk-vetch possesses a perennial taproot, surveyors observed that the herbaceous aboveground portion of the plant appeared to respond to some extent to annual and multi-year climatic conditions. To learn more about the annual variation in climate (amount and timing of rainfall) and plant response, two long-term studies were conducted to monitor the Lane Mountain milk-vetch. The first study was conducted by researchers from UCLA and was an outgrowth of their earlier research on the basic biology of the species that was sponsored by the Army. The second study was carried out by Army staff, and was a part of their Integrated Natural Resources Management Plan. These studies indicate that different life history stages of the plant respond differently to variation in climate.

The UCLA long-term study monitored the Lane Mountain milk-vetch within four 2.5-ac (1-ha) plots. Two plots were established in 1999 at the Brinkman Wash-Montana Mine population and two in 2003 at the Goldstone population. These plots were initially chosen because of their high density of Lane Mountain milk-vetch plants compared to adjacent areas, and therefore represent areas of unusually high densities within the Brinkman Wash-Montana Mine and Goldstone populations (Huggins et al. 2012b, p. 7). The data from these plots cannot be used to accurately estimate the density of Lane Mountain milk-vetch plants within each population as they would overestimate the population size. The plots were visited multiple times throughout the year. During this study, researchers tagged plants and recorded data on the number and density of Lane Mountain milk-vetch plants in these plots and the phenological stages (e.g., seedling, mature plant, and flowering).

The results from the UCLA study of the Lane Mountain milk-vetch in the field showed that Lane Mountain milk-vetch does not reproduce vegetatively. It depends on seeds to recruit new individuals into a population (Rundel et al. 2006, p. 7). Seeds produced during the previous growing season may germinate and begin to establish a taproot but most seedlings do not survive. In years with more rainfall, individuals may grow vegetatively and produce flowers and seed to varying degrees depending on other factors such as frequency of precipitation (Rundel et al. 2006, p. 30). If subsequent years have sufficient rainfall, individuals will persist for two or more years. In years with little rainfall, taproots of established Lane Mountain milk-vetch plants may remain dormant and few plants will resprout, or plants may die.

The results from the multiple-year UCLA study indicate an overall negative population trend for the species. During the 13-year study period from 1999 to 2011, the monitored Lane Mountain milk-vetch plants in the plots at the Brinkman Wash-Montana Mine population declined from 44 to 16 plants. During a 9-year study period from 2003 to 2011, the monitored Lane Mountain milk-vetch plants in the plots at the Goldstone population declined from 43 to 14 plants (Huggins et al. 2012b, p. 30). This decreasing trend included two years of high precipitation in 2005 and 2011, when Lane Mountain milk-vetch population increases of 47 percent and 36 percent respectively, occurred. The greatest observed decrease in annual population size, which was 63 percent, was associated with a severe drought in 2007. Since 2007, Lane Mountain milk-vetch populations have remained stable but low.

In 1999, UCLA researchers conducted numerous surveys for Lane Mountain milk-vetch in areas of Brinkman Wash, Montana Mine, near the north slope of the Paradise Range, and the northeastern end of Lane Mountain (Prigge et al. 2000aa, p. 2). All Lane Mountain milk-vetch plants that were found were tagged. Of the 810 plants that Prigge et al. (2000, p. 6) found, 201 tagged were mature Lane Mountain milk-vetch plants in the Brinkman Wash-Montana Mine population. By 2004, less the 22 percent were confirmed to be living (Rundel et al. 2005, p. 10). The remaining 78 percent of Lane Mountain milk-vetch plants were vegetative (produced stems and leaves but no flowers), dormant, or dead. Most milk-vetch plants found again had no aboveground living tissue. These were presumed dormant, but may have died since they were tagged 5 years earlier. At the Goldstone population where 65 Lane Mountain milk-vetch mature plants were tagged in 2001, the confirmed survival rate 3 years later was 65 percent. This difference in the survival rate between the two populations could be caused by differences in environmental factors at the sites (e.g., frequency and timing of precipitation) (Rundel et al. 2005, p. 11).

Most Lane Mountain milk-vetch plants may not survive for several years. Of the Lane Mountain milk-vetch plants first surveyed in 1999 and 2003, Huggins et al. found that long-term survival was low: 14 percent at the Brinkman Wash-Montana Mine study plots and 9 percent at Goldstone study plots (Huggins et al. 2011, p. 11). From 1999 to 2003, the Brinkman Wash- Montana Mine population had 61 percent mortality, a period that included moderate drought in 1999 and 2000, and severe drought in 2002, the driest year since 1949. Mortality then slowed, in 2007 increased to 40 percent of the remaining population, and then stopped. Population survival within the Goldstone population can be divided into three distinct periods: (i) moderate decline from 2003 to 2006, (ii) high mortality (79 percent) in 2007, and (iii) stasis from 2007 to 2011 (Huggins et al. 2011, p. 11).

Huggins et al. (2010a, p. 122) reported that despite these decreases in mortality in recent years, Lane Mountain milk-vetch numbers remain very low. In summary, during this study from 2003 to 2011, the Brinkman Wash-Montana Mine and the Goldstone populations of Lane Mountain milk-vetch have undergone population contractions from 44 and 43 plants, respectively, in 2003 to 16 and 14 plants in 2011 (Huggins et al. 2012b, p. 31). This is a population reduction of 64 and 68 percent, respectively, leaving some monitored populations at critically low levels, and in danger of local extinction (Huggins et al. 2012b, p. 2).

Table 3. Annual population data for Lane Mountain milk‐vetch at the four 1‐ha UCLA study plots (Huggins et al. 2012b, p. 30).

Brinkman Wash-Montana Mine Population Goldstone Population Number of Number of Percent Number of Number of Percent Year Individual Plants Change from Individual Plants Change from Plants Gained/Lost Baseline Year Plants Gained/Lost Baseline Present since Previous Present since Year Survey Previous Survey No data 1999 44 collected No data 2000 Not reported collected No data 2001 Not reported collected No data 2002 Not reported collected 2003 18 0/26 -60 43

2004 16 0/2 -64 37 0/6 -14

2005 25 _ 9/0 -43 46 9/0 7

2006 19 0/6 -57 40 0/6 -7

2007 10 0/9 -78 10 0/30 -77

2008 12 2/0 -73 9 0/1 -79

2009 13 1/0 -71 7 0/2 -72

2010 14 1/0 -68 8 1/0 -71

2011 16 2/0 -64 14 6/0 -68

Total 15/43 16/45

Figure 4. Lane Mountain milk‐vetch growing season precipitation and population dynamics at UCLA study plots from 1999 to 2011. The years refer to the spring season in which the species is reproductive. Population data were not collected from 2000 through 2002 (red dashed line). Population data for 1999 were derived by adding data collected at some sites in 1999 to data collected in 2003 and extrapolated to 1999. Mean precipitation was 4.4 in (112 mm) per growing season (from Huggins et al. 2012b, p. 26) The black dashed line is mean growing season precipitation (October‐May) during the wet period from 1978‐1998 (128 mm per growing season). Mean precipitation during the recent period (1999‐2011) was 112 mm per growing season.

Population Model

Using population data available for the Lane Mountain milk-vetch, Rundel et al. (2005) developed a preliminary model of Lane Mountain milk-vetch population size spanning past and future years (Rundel et al. 2005, p. 11). They assumed that Lane Mountain milk-vetch mortality and recruitment observed at the UCLA long-term study plots is characteristic of the species across its range. They applied a survival rate of 22 percent for the 210 living Lane milk-vetch plants tagged in 1999 (or mortality of about 78 percent) and other factors in developing their model (Rundel et al., 2005, p. 10). The model results predicted that in 2006 the number of Lane Mountain milk-vetch plants would continue to decline to less than 30.

Huggins et al. (2010a, p. 123) updated this model with additional populations data collected since 2005. They assumed that rates of recruitment and mortality for the Lane Mountain milk-vetch at the four study plots in the Brinkman Wash-Montana Mine and Goldstone populations were similar to that throughout all four populations. They applied these assumptions to the data collected at the study plots to the total number of Lane Mountain milk-

vetch plants found during the extensive survey efforts through 2001. Huggins et al. (2010, p. 123) calculated that, of the total number of 5,723 Lane Mountain milk-vetch plants found through 2001 (Charis 2002, p. 34), about 686 Lane Mountain milk-vetch plants would have been present in 2009. This is about an 88 percent reduction in the number of individuals in the species and no evidence of recruitment. Huggins et al. (2010a, p. 120) concluded that all monitored populations have dropped to critical levels and are at risk of local extinction.

In addition, Huggins et al. (2013c) developed a population model using data on precipitation and population data since 1999. After initial development, they refined the model to include drought-tolerant recruitment and mortality. The models were applied using historical rainfall data to model the historical population trend for Lane Mountain milk-vetch (Figure 5). Using linear regression, the “initial model” explained 92 percent of the variation and the “drought-class model” explained 85 percent. The “initial model” produced a 7 percent better fit to the observed data than the “drought-class model (Huggins et al. 2013c, p. 141). Both models showed a substantial population decline in 2002 and 2007. Both models indicate that the current population level of the Lane Mountain milk-vetch is at or near the lowest level during the last 65 years.

Figure 5. Trend of historical Lane Mountain milk‐vetch population using models developed from data on precipitation and population size (taken from Huggins et al. 2013c, p. 136).

From 2005 to the present, the Army established 164-ft2 (50-m2) permanent plots at 10 locations within each of the four populations of Lane Mountain milk-vetch. The locations of these plots were selected based on the locations of highest densities of Lane Mountain milk- vetch plants within each population as documented by the Charis surveys (Hessing 2005, p. 10). Because the Lane Mountain milk-vetch plots are not randomly distributed within the Lane Mountain milk-vetch populations, they cannot be used to estimate the density of Lane Mountain milk-vetch plants within each population (Hessing 2005, p. 10). Because of the selection criterion, they likely indicate an inflated value of the number of plants present in the populations. The Army conducted a census by counting all Lane Mountain milk-vetch plants found within the 40 plots. The plant count began during the middle of the Lane Mountain milk-vetch growing season (April) and ended in (July). Each plot was visited once during the annual survey effort (Hessing 2005, p. 11). The number of plants found per plot during the census activities has ranged from 0 to 31 plants. Plants counted included seedlings and mature plants. Data on reproductive output (i.e., the number of flowers and the number of fruits per plant) were recorded. No data on plant size or plant age (i.e., seedling or mature plant) were recorded consistently during the study.

The results from the Army’s monitoring of the 40 plots from 2005 to 2012 showed that the average number of Lane Mountain milk-vetch seedling and mature plants per plot per year ranged from a high of 5.9 in 2006 to a low of about 0.2 in 2007 (Hessing and Shaughnessy 2011, p. 56) (Table 4). The total Lane Mountain milk-vetch plants counted on all 40 plots ranged from 232 in 2006 to 4 in 2007. From 2008 to 2011, the number of Lane Mountain milk-vetch seedling and mature plants counted increased from 125 to 196, then decreased in 2012 and 2013. The overall trend showed the total number of seedlings and mature plants generally following the rainfall pattern for each year (Figure 6). That is, in years with less rainfall, the number of seedling and mature Lane Mountain milk-vetch plants counted was lower and in years with more rainfall, the number of plants recorded was higher. If insufficient rainfall occurs, Lane Mountain milk-vetch plants may abort flower production (Charlton 2007, p. 28) or flowers and fruits may disappear before developing into mature fruits, (Hessing and Shaughnessy 2011, p. 38). Therefore, substantial contributions to the seed bank may occur only in climatically favorable years.

In the latest report, Hessing (2012, p. 5) in 2012 reported a 40.9 percent decrease in the number of Lane Mountain milk-vetch plants when compared to 2011. All living plants were barely alive, with stunted and unusually small leaves, and stems that did not extend past the canopy of the nurse shrub. Some plants had no developed leaves, only living buds. He attributed the failure of above-ground growth to severe lack of precipitation during the growing season and reported similar drought conditions in 2002 and 2007. No seedlings were observed in the 40 study plots. No plants flowered in 2006, 2007, and 2012. Some Lane Mountain milk- vetch died after droughts, whereas no milk-vetch died between the wet years 2010 and 2011. In 2013, two populations increased in number of plants found and two populations decreased (Houseman et al. 2013, p. 3) (see Table 4).

If we apply the data from the Army’s 40 study plots to the total plants found during the Army’s multi-year survey effort, the estimated number of Lane Mountain milk-vetch plants that would be present today is in Table 5. Because of the selection criteria for locating the study

36 plots, when the data from these plots are used to estimate the population size, the result is likely an overestimate of the Lane Mountain plants in the populations.

Table 4. Census results from the Army’s 40 permanent 50 meter2 study plots, 10 within each of the four populations of the Lane Mountain milk‐vetch (LMMV). Rainfall data are averaged from 3 to 11 columnar gauges in or adjacent to LMMV population locations. Sum of Sum of Sum of Brinkman Sum of Sum of All Plots Rainfall* Paradise Year Coolgardie Wash- Goldstone including (inches/mm) Valley Mesa Plots Montana Plots Seedlings Plots Mine Plots 2001 4.2/1072 1571 931 701 601 380

2002 1.9/48.3

2003 5.3/134.6

2004 4.0/101.6

2005 15.1/383.5 931 411 481 421 2241

2006 2.8/71.1 1071 551 331 351 2301

2007 0.7/17.8 21 01 21 01 41

2008 2.9/73.4 491 261 271 211 1231

2009 1.8/45.7 551 241 221 241 1243/128 4

2010 5.3/134.64 614 354 294 274 1524

2011 5.7/144.85 855 455 415 305 1985/1896

2012 0.7/17.86 646 486 146 86 1176

2013 1.2/~307 607 187 207 167 1147

Percent Change from -62 -80 -71 -73 -70 Baseline Year

*Hessing 2009, pp. 3, 8, 11–18. Rain year is October 1 through September 30 (Hessing 2009, p. 3). 1Hessing 2008, pp. 2 and 5 2 Huggins et al. 2012, p. 26; extrapolated from a graph 3 Hessing 2009, p. 3. 4Hessing 2010, pp. 4, 14–23. 5 Hessing and Shaughnessy 2011, p. 36. 6Hessing 2012, pp. 5 and 10. Rain year is October 2011 through April 2012. 7Housman et al. 2013, p. 5

Figure 6. Annual population census for all Lane Mountain milk‐vetch plants in the Army’s forty 50 m2 study plots, including seedling and mature plants through 2012.

400 20 Rainfall (inches) 350 15

300 10 5 250 0 200 123456789101112

150 Sum of Goldstone Plots 100 Sum of Brinkman Wash‐ 50 Montana Mine Plots Sum of Paradise Valley Plots 0 Sum of Coolgardie Mesa Plots

Table 5. Estimate of population size of Lane Mountain milk‐vetch plants in four populations in 2013 using population data from the Army’s 40 study plots (see Table 2). Polygon Size in Percent of Number of Number of Individual Acres Total Area of Individual Plants Plants Projected to Be Population (Hectares)1 Polygons Located from Present in 20132 1999-2001 Goldstone 1,283 (519) 6 555 211

Brinkman Wash- 297 5,497 (2,225) 26 1,487 Montana Mine

Paradise Valley 4,794 (1,940) 22 1,667 483

Coolgardie Mesa 9,775 (3,956) 46 2,014 544

Total 21,349 (8,640) 100 5,723 1535 1 Includes a 98‐ft (30 m) buffer around the minimum convex polygon method for determining area. 2 Numbers are likely inflated because of criteria used to locate study plots.

The intensive survey effort that the Army conducted from 1999-2001 delineated the distribution of the Lane Mountain milk-vetch and surveyed most of area with suitable habitat for the species. It was a multiple year survey; this means that if Lane Mountain milk-vetch plants were dormant in one year, they would likely have resprouted and been observed in another year. Another possibility is that plants may have been counted more than once, inflating the actual

number of Lane Mountain milk-vetch plants reported as plants were not tagged. The total number of Lane Mountain milk-vetch plants counted during the 1999-2001 surveys was 5,723. We conclude that most of the Lane Mountain milk-vetch plants present during this time were located because of the magnitude and duration of the survey.

Summary

The results from the two long-term studies on the Lane Mountain milk-vetch by UCLA and the Army indicate that the population size has substantially decreased since 1999, and this decrease appears to follow precipitation amount and frequency during this period. Adult Lane Mountain milk-vetch plants have the ability to persist during a dry year by reducing or curtailing reproduction, limiting vegetative growth (resprouting) or remaining dormant as a taproot below ground until the next year. Despite these adaptations, population numbers have declined. Seedling survival and recruitment may be most vulnerable to precipitation amounts and frequency as it appears that two successive years of above average precipitation are needed for a seedling to survive and flower. If in the future, dry years continue to outnumber wet years as they have since 2000, we expect the population size of the Lane Mountain milk-vetch to continue to decline.

Overview of Factors Affecting the Species

Threats at the time of listing (1998)

At the time of listing in 1998, we identified the primary threats to the Lane Mountain milk-vetch as: mining; off-highway vehicle (OHV) use and general recreation; military training and operations; inadequate protection under the Act, the Federal Land Policy Management Act and implementing regulations and policies; the potential for increased fire frequency and size and associated fire suppression activities; and reduction or loss of and vulnerability to extinction because of small population size from random (stochastic) natural events (63 FR 53604–53605, 53608-53609). We did not identify existing and potential permitted development on private lands in the range of the Lane Mountain milk-vetch.

Threats discussed in the 5-year review (2008)

In addition to the threats discussed at the time of listing, the 5-year review for the Lane Mountain milk-vetch added threats from: potential energy development; vegetative, root, and seed predation; inadequate protection under the Mining Law of 1872; increased fire frequency including the loss of nurse shrubs; infrequent recruitment; increased abundance of nonnative species resulting in competition with Lane Mountain milk-vetch seedlings for limited resources such as space, light, and nutrients; and reduction or loss of gene flow between populations and reproductive isolation. We did not identify existing and potential permitted development on private lands in the range of the Lane Mountain milk-vetch.

In the 5-year review, based on the likelihood of future implementation of various management actions by BLM and the Army, we thought that the threats from mining and OHV activities would be reduced with the transfer of about half the Lane Mountain milk-vetch habitat from the BLM to the Army in 2002. Additional measures identified which lead us to our 39

conclusion included the adoption and imminent implementation of the Final Environmental Impact Report and Statement for the West Mojave Plan, A California Desert Conservation Area Plan Amendment (West Mojave Plan) by the BLM in 2005. Several actions described in the West Mojave Plan would, when implemented, reduce threats to the Lane Mountain milk-vetch. These included withdrawing ACEC lands from mineral entry (with some exceptions), installing protective fencing in an area of heavy OHV use, closing excess roads on BLM lands, implementing a public education program, and enforcement and monitoring of these actions.

Regarding military training and operations activities, we calculated that the Army’s existing and proposed activities would directly affect and likely result in the loss of about 23 percent of the Lane Mountain milk-vetch habitat. However, the Army planned to conserve about 30 percent of the range of the species, including establishing two conservation areas on its lands and a third area that would be subject to surface disturbance but not tracked vehicle training.

Current Threats (2013-2014)

All threats described in the listing and 5-year review still exist, though some have changed in intensity or imminence. In this species report, we identify and discuss these threats and the additional threats of drought and climate change; habitat fragmentation; inadequate protection under local, State, and Federal laws and regulations; and natural random events because of the small population size, number of populations, and their isolation. The threats from existing and potential permitted residential development on private lands have been removed from many of the private lands in the Coolgardie Mesa and West Paradise Conservation Areas (see Military Training and Operations Activities-Conservation Measures). We discuss the current level of concern that each of the identified threats poses to the Lane Mountain milk- vetch, and the change in the discussion of threats since listing is represented in Table 6. We present a full discussion of past and present threats in the report. In addition, the conservation measures that BLM identified in the West Mojave Plan (BLM et al. 2005) for the most part have not been implemented.

Table 6. Population information and threats to the Lane Mountain milk‐vetch since listing. 1998 2008 2013-14 (Time of listing) (5-year Review) (Species Report) Species Information Abundance (individuals in all 950 known; 5,723 reported from 686; Estimated populations) Estimated 1999-2001; population size is population size is Estimated population 1,535 in 2013 2200+ size may be slightly larger or smaller Distribution 3 populations 4 populations 4 populations Areal extent 355 acres Not calculated; Before military (144 hectares) training: 21,256.3 acres (8,602 ha); after military training: 4,561.4 acres (1,845.0 ha)

1998 2008 2013-14 (Time of listing) (5-year Review) (Species Report) Closest Distance between 0.6 and 1.4 miles 2.3 and 2.0 miles 2.3 and 2.0 miles Populations (1.0 and 2.2 km) (3.7 and 3.2 km) (3.7 and 3.2 km)

Threats

Military Training and    Operations Activities Mining Activities    Off-highway Vehicle    Activities Energy Development ----   Anthropogenic Dust ----   Development on Private ----1 ----1 ----1 Lands Predation ----   Infrequent Recruitment ----   Increase and Spread of ----   Nonnative Species/Competition Fragmentation or Reduction/ ----   Loss of Connectivity Increase in Fire Frequency,    Size, and Intensity Precipitation Patterns, ----   Drought, and Climate Change Reduced Population    Persistence/Vulnerability from Natural Random Events Reduced Gene Exchange or ---- ?  Genetic Isolation Regulatory Mechanisms    1 Previously a threat but not identified in 1998 final rule listing the Lane Mountain milk‐vetch or the 2008 5‐year status review. This threat was substantially reduced shortly after 2008 with the Army’s purchase of most of the private lands in Coolgardie Mesa and West Paradise Conservation Areas.

Threats to Habitat from Surface Disturbance

Military Training and Operations Activities

At the time of listing, we identified the loss or degradation of habitat from ongoing military training and operations at Fort Irwin as a threat to the Lane Mountain milk-vetch. In the 5-year review, we continued to identify this threat, and we identified the Army’s recent acquisition of land to expand their force-on-force military training and operations. The land acquisition, called the Western Expansion Area, included the remaining portion of the Brinkman Wash-Montana Mine population and about 90 percent of the Paradise Valley population of the

Lane Mountain milk-vetch. Although the Army had planned to initiate training and operations in the Western Expansion Area in 2009, this initiation has been delayed (Army 2011). We describe the current and potential threats to the Lane Mountain milk-vetch from military training and operations activities below.

Description of Military Training and Operations Activities at Fort Irwin

Fort Irwin has three major management units, the National Training Center (NTC), the Goldstone Deep Space Communications Complex (Goldstone Complex), and the Leach Lake Bombing Range. We will not discuss the last management unit as no Lane Mountain milk- vetch occurs in this area.

There are two types of training at NTC, live fire training and force-on-force training using laser beams to simulate bullets, missiles, and artillery projectiles. Live fire training is not scheduled to occur in the Western Expansion Area, which includes the distribution of the Lane Mountain milk-vetch (Army 2003, Chapter 2 pp. 5–6).

The NTC provides training for brigade-level units in highly realistic combat situations. A brigade is two or more regiments or three to six battalions; its size is usually 3,000 to 5,000 soldiers (Fort Irwin Integrated Natural Resources Management Plan (INRMP) 2005, p. 2). Training at the NTC includes foot traffic of 3,000 to 5,000 soldiers per exercise and setting up temporary camps, the use of tanks and other tracked and wheeled vehicles to haul and use soldiers, equipment, and supplies. Rotational units use up to 260 vehicles, including 70 tanks, per rotation, with several rotations occurring per year (Army 2005 SFEIS, Chapter 3, p. 212). Army personnel operate these vehicles off paved roads, cross country, and on existing dirt roads to move and use soldiers, weapons, equipment, and supplies. Vehicles and equipment are used for construction, digging and earth-moving activities, temporary encampments, helicopter landings, moving soldiers on foot, and other activities in the project area (Army 2003, Chapter 2, pp. 6–10)). Training also includes military support activities such as construction of training structures or caves, erecting radio towers, and laying fiber optic cable (Army 2006 INRMP section 9.5.2.1).

In addition to ground training, there is air training. About four times a year, airborne or air assault battalions, consisting of 600-800 light infantry soldiers and associated low-flying helicopters, also participate in training maneuvers at Fort Irwin. These units train in conjunction with mechanized units during normal rotations. Airborne and air assault brigades of up to 4,000 soldiers and 80 helicopters also train at Fort Irwin. Because of their air mobility and ability to operate in any terrain, these units maneuver over a wider terrain segment (including the mountain areas) within the Fort Irwin boundaries and can train in all parts of the maneuver and project area (Army 2003, Chapter 2, p. 9).

Support and staging areas are required as part of the training exercise. These areas are set up on the battlefield and contain ammunition, supplies, fuel, maintenance, mess, and other logistical support as well as medical evacuation units, special engineer units, and other “on call” support. These areas are called Tactical Assembly Areas (TAA) and Brigade Support Areas (BSA). Five separate TAAs are established during each rotation for 2–4 days each.

They each involve an area of approximately 1.52 mi (2.42 km). Four BSAs are established during each rotation for 3–7 days each. They each involve an area of approximately 22 mi (3.22 km) (Army 2003, Chapter 2, p. 10).

At the NTC, the Army has subdivided the ground vehicle maneuver training areas into high-use, medium-use, low-use, and no-use (Army 2003, Chapter 2, p. 6). A high use area is an area with unlimited cross-country movement by all vehicle types (e.g., tanks, armored personnel carriers, supply trucks, etc.). In a medium-use area, movement by all vehicle types is allowed, but restricted to roads, staging areas, or assembly areas, but vehicle movements may occur throughout the training area where roads in these areas occur. Dismounted traffic (e.g., foot soldiers) within medium-use areas is not restricted. In low-use areas, all vehicle types are located on roads, there are no staging areas, and only dismounted traffic (foot soldiers) occurs off-road. No-use areas are off limits to vehicle entry and to training by foot soldiers except as authorized (Army 2005 SFEIS, Chapter 2, p.1; Everly 2013 in litt. email dated 12-6-2013).

Training exercises typically last from 31 to 38 days and occur 10 times per year (Army 2003, Chapter 2, p. 7). Each rotational unit transports its soldiers, vehicles, and equipment from its home base to the NTC for the exercise and they return to their home base afterward (Army 2003, Chapter 2, p.5), thus these are moved to and from the NTC every few weeks.

On January 11, 2002, President Bush signed the Fort Irwin Military Lands Withdrawal Act of 2001 (Public Law 107–107). This legislation withdrew 118,674 ac (48,026 ha) of land from BLM management to Department of Defense management in two areas, the Eastern Expansion Area and the Western Expansion Area (Service 2010, 75 FR 16404, 16408). The withdrawal of BLM lands expanded the size of the NTC to 642,558 ac (260,035 ha). On March 15, 2004, the Service completed a biological opinion on the proposed addition of training lands at Fort Irwin (Service 2004 (1-8-03-F-48), pp. 1–73). The Army plans to initiate brigade-level training maneuvers and activities in the 75,300-ac (29,745-ha) Western Expansion Area and continue training in the remaining portion of the NTC. Although the Army accepted BLM-withdrawn lands including the Western Expansion Area and planned to initiate brigade-level training by 2012, they recently decided not to pursue this level of training activities in the Western Expansion Area at this time (Army 2011, p. 1, letter dated December 27, 2011 to the Service). In the future and following completion of the Army warfighting doctrine analysis, the Army will reassess its training needs. The decision is based on current uncertainties about budget, the withdrawal of United States military forces from around the world, and the ongoing review and analysis of current Army warfighting doctrine (Everly 2012 in litt., August 8, 2012). However, the Army will retain these lands as they anticipate needing them for future training activities.

The Goldstone Complex, which is 33,359 ac (13,500 ha), is leased to and operated by the National Aeronautics and Space Administration (NASA) for tracking and communications for space missions. NASA’s facilities at Goldstone were previously constructed and there operation does not result in new or ongoing surface disturbance. There are no plans to construct additional facilities in the future. The Goldstone Complex is off limits to Army training activities with the exception of continued use of the existing tank trail constructed in 1985 that bisects most of the Complex (Army 2003, Chapter 2, p.12). Called the Goldstone Transit Route, this 30-ft (9.1-m)

wide trail would be resurfaced using low-dust compacted gravel, resin-impregnated pavement, or concrete. The route would likely require 12-ft (3.7-m) graded shoulders on each side and numerous culverts to provide adequate drainage using gravel or concrete and 12-ft wide shoulders added to each side of the road.

Location of Military Training and Operations with Respect to the Lane Mountain Milk-vetch Populations and Its Habitat

When the Lane Mountain milk-vetch was listed in 1998, the Goldstone population and about 25 percent of the Brinkman Wash-Montana Mine population occurred within the boundary of Fort Irwin (Goldstone Complex and NTC). Thus, 12.4 percent of the Lane Mountain milk-vetch populations and habitat were located within Fort Irwin. With the Army’s acquisition of the Western Expansion Area in 2002, the new boundary for Fort Irwin (Goldstone Complex and NTC) contains the entire Goldstone and Brinkman Wash-Montana Mine populations and more than 90 percent of the Paradise Valley population of the Lane Mountain milk-vetch. Now 11,567 ac (4,681 ha) or 54.2 percent of the Lane Mountain milk- vetch populations and habitat are located within Fort Irwin.

The entire area within the NTC is not used for ground forces training, as some of the terrain is not suitable for training and some areas are set aside as buffer zones to shield the training activities from civilian uses on lands adjacent to the base’s boundary. Thus, while some areas are intensively used for ground forces training, others are not subject to direct use. However many areas that are not used for ground forces training are in rugged terrain, which is also not suitable habitat for the Lane Mountain milk-vetch.

Within the NTC, we estimate that about 6,660 ac (2,695 ha) of known Lane Mountain milk-vetch habitat and the Lane Mountain milk-vetch plants in this habitat would be subject to direct impacts from military training and operations activities. This represents 31.2 percent of populations and habitat for the species (see Regulatory Mechanisms, Department of the Army, for additional discussion on the Western Expansion Area) (Army 2003, Chapter 5, p. 25) and 57 percent of the populations and habitat within the Fort Irwin boundary. If and when the Army moves forward with training plans, they would conduct: high-use training activities in the northeast portion of the Paradise Valley population, high and medium-use training in the northern half and southeast portion of the Brinkman Wash-Montana Mine population, and high and medium-use training between the Paradise Valley, Brinkman Wash-Montana Mine, and Goldstone populations (Army 2005, Chapter 2 p. 3; see Figure 6). Additional areas of Lane Mountain milk- vetch plants and habitat could be adversely affected from the indirect impacts of military training and operations activities and accidental unauthorized direct impacts (see Effects of Military Training and Operations Activities below).

Figure 7. Map of projected military training intensity in Western Expansion Area of Fort Irwin and location of Lane Mountain milk‐vetch populations and conservation/restricted use areas.

Goldstone Population: About 80 percent of the 1,283-ac (519-ha) Goldstone population of the Lane Mountain milk-vetch (1,124 ac; 455 ha) is located on lands within the NTC while 20 percent (159 ac; 64 ha) is within the NASA Goldstone Complex. The 80 percent within the NTC is in a no-use area (see Conservation Measures Implemented). The Goldstone population of the Lane Mountain milk-vetch borders existing medium-use military training areas to the south (Training Area B1) and east (Training Area B2), and a proposed medium-use training area to the west (Army 2005 SFEIS, Chapter 2, p. 3). Current military training in Areas B1 and B2 is usually for squad exercises (Hessing 2009, p. 1). The size of a squad depends on its function but is usually 8 to 13 men with associated vehicles, equipment, and support activities.

Brinkman Wash-Montana Mine Population: The Brinkman Wash-Montana Mine population is about 5,498 ac (2,225 ha) and is located entirely within the NTC. Of this, 4,360 ac (1,764 ha) is subject to military training and operations activities that include high use and medium use training areas(Army 2003, Chapter 5, p. 25). The remaining area, about 1,711 ac (692 ha), is located in an area designated for low-use military training, sometimes referred to as the No Dig Zone. The Brinkman Wash-Montana Mine population is bordered on the east by areas designated for medium- and high use military training, on the south by BLM land, on the west and north by areas designated for medium- and high use military training.

Paradise Valley Population: More than 90 percent of the 4,692-ac (1,899-ha) Paradise Valley population of the Lane Mountain milk-vetch is located in the NTC. About 77 percent (3,252 ac (1,316 ha)) of this population is in a no-use military training area designated by the Army (see Conservation Measures Implemented). The remaining 23 percent of this population (1,543 ac (624 ha)) is in an area designated for medium- to high use military training (Charlton 2007, p. 29; Army 2003 Chapter 5, p. 25; Army 2005, Chapter 2, p. 3). The Paradise Valley population within Fort Irwin is bordered on the north and east by designated medium- and high use military training areas, on the south and west by BLM land.

Effects of Military Training and Operations Activities to the Lane Mountain Milk-vetch and Its Habitat

In general, direct and indirect impacts to Lane Mountain milk-vetch plants and habitat will depend on the intensity and location of military training and operations activities. Impacts from these activities will range from zero direct impacts in no-use areas, to 100 percent of the habitat and individuals of Lane Mountain milk-vetch in high use areas (Army 2003, Chapter 5 p. 20). Direct impacts would likely range from minor habitat alteration and vehicle route proliferation in low-use areas to total denudation of extensive areas caused by construction and use of staging areas, roads, bivouacs, fighting positions, and the frequent and intensive use of tracked and wheeled vehicles in high use areas. Indirect impacts would range from dust deposition at no-use areas farthest from the training areas to destruction of soil structure, disruption of soil function, soil erosion, disruption of pollination systems, spread and increase of existing invasive plants and introduction of new species of invasive plants, alteration of historic fire regimes, changes in vegetation types, and fragmentation of Lane Mountain milk-vetch populations and habitat in high use areas.

Most military training and operations activity would occur in areas that are flat or with less rugged terrain without obstructions such as boulders and rock outcrops, with the exception of helicopter training. Rugged areas (rocky hills and mountains) are usually avoided. However, areas with high ridges will tend to concentrate the movement of vehicles and troops along existing roads and trails, washes, and divides. Areas surrounding the battle corridors usually have terrain that is rocky and uneven, although technically, most of these areas are maneuverable and could experience degradation or loss of habitat from various activities including military vehicles straying into areas adjacent to roads and use of these areas for bivouac sites (Krzysik 1994b, p. 98). The Lane Mountain milk-vetch is located in less rugged terrain. We expect the impacts from planned military training and operations activities in the Western Expansion Area, some of which contains Lane Mountain milk-vetch plants and habitat, to be the same as areas currently occurring from ground forces training in the NTC.

Destruction of Lane Mountain milk-vetch Plants and Nurse Shrubs: Military training maneuvers and activities affect Lane Mountain milk-vetch plants and habitat by crushing plants and seeds, uprooting plants, and substantially reducing or eliminating nurse shrubs (Army 2003, Chapter 5, pp. 22–30). For high use areas, military training activities could ultimately impact, and cause the loss of, up to 100 percent of the habitat and individuals of Lane Mountain milk-vetch (Army 2003, Chapter 5, p. 25). In a study on changes in shrub cover at the NTC and Fort Irwin, Krzysik (1994b, p. 66) reported that in control areas (areas off limits to military training), shrub cover ranged from 19 to 25 percent, while in the training areas, it was 0.8 to 1.9 percent. He also measured the rate at which this change occurred. After several years of training, shrub cover declined an additional 67 percent in the high use training areas and 51 percent on the higher bajada areas with less intense training activity during a 6-year period. Over time, the training areas will have reduced native shrubs present, with the high use areas eventually being devoid of vegetation in much of the area (Army 2003, Chapter 5, p. 25). Therefore, high use military training areas in known locations of Lane Mountain milk-vetch populations would have a similar impact on vegetation including nurse shrubs and Lane Mountain milk-vetch plants; medium -use training areas would have a similar impact but to a lesser degree (e.g., higher bajada areas).

With the degradation or loss of nurse shrubs, other environmental effects would likely occur including increases in soil and air temperatures, decreases in soil moisture and organic material, and reduction or removal of protection from predators in Lane Mountain milk-vetch habitat. Some or all of these impacts would make the persistence of Lane Mountain milk- vetch plants and nurse shrubs and establishment of new plants and nurse shrubs unlikely.

Destruction of Soil Structure and Disruption of Soil Function: Soil and plant characteristics of low- and mid-elevation desert ecosystems in the U.S., including the western Mojave Desert, indicate that these ecosystems evolved with low levels of soil surface disturbance (Belnap et al. 2001, p. 41). Cryptobiotic soil crusts (see below) play an important role in the Mojave Desert for soil stabilization and other soil processes. They are collections of symbiotic bacteria, algae, fungi, and lichen that live on or slightly below the soil’s surface and create a semipermeable soil surface or crust. These delicate soil crusts reduce soil erosion, promote and control water infiltration, regulate soil temperatures, catch and convert atmospheric nitrogen, accumulate organic matter, and facilitate native seedling establishment and growth (Boarman 2002, pp. 46–47), and thus aid in the maintenance of habitat for the Lane Mountain milk-vetch and nurse shrubs.

Soil crusts are highly susceptible to degradation from the frequent and large-scale disturbance activities recently introduced in the western Mojave Desert. With the recent degradation of soil crusts, dust at its current levels is likely a recent phenomenon to the Mojave Desert. Because of their evolutionary history, these arid regions appear to be more negatively affected by soil surface disturbances than regions such as the Great Plains that evolved with higher levels of surface disturbance (Belnap et al. 2001, p, 42) (e.g., herds of large grazing animals and fire).

Military training at the NTC replaces tight, cohesive gravelly soil surfaces with loose, sandy substrates (Krysik 1994b, p. 98). Once disturbed, soils in the Mojave Desert are easily

eroded by wind and water (Army 2006 INRMP, p. 47) with wind erosion producing airborne dust (see Increase in Wind Erosion of Soils and Dust Deposition below). Vehicle use and heavy foot traffic during military training and operations activities disturb or destroy cryptobiotic soil crusts, making the soil vulnerable to erosion from wind and water

Desert soils are also highly vulnerable to compaction and disruption of soil functions (Army 2006 INRMP, p. 47) from military training activities including the use of wheeled or tracked vehicles. Military training and operations activities compacts soils and disrupts soil functions. Compacted soils reduce the infiltration rate of rain, which means there is less water available for plant growth, reproduction, and seed germination (Boarman 2002, p. 46). Compacted soils reduce the root growth of established plants; and make it difficult for seedlings to survive (Lovich and Bainbridge 1999, p. 316). With soil compaction, soil erosion from wind (see Anthropogenic Dust below) and water increases, nitrogen fixation is reduced, less organic material is available for plant growth, and seedling establishment is reduced (Lovich and Bainbridge 1999, pp. 315–316; Boarman 2002, pp. 45–46). Consequently, these impacts to soils would alter or prevent Lane Mountain milk-vetch plants and nurse shrubs from surviving, reproducing, and recruiting new plants.

Areas where force-on-force training is planned would have similar impacts to vegetation and soils as areas currently used for this training. These areas on Fort Irwin are degraded to the point that they retain little vegetative cover (Army 2003-BA, Chapter 5, p. 23). Krzysik (1994, p. 29) documented the impacts of ground forces training on the vegetation and soils at Fort Irwin. They included extensive losses of shrub cover, soil layers, and cryptobiotic soil crusts.

The effects of vegetation removal, soil erosion, loss of cryptobiotic soil crusts, and compaction due to wheeled and tracked vehicle use in the Mojave Desert have been shown to last decades, and may be permanent in the absence of restorative actions (Bolling and Walker 2000, p. 21; Prose and Wilshire 2000, pp. 17–18; Okin et al. 2001, pp. 137 and 139; Army 2003, Chapter 5, p. 19). Long-lived woody species are particularly vulnerable to such disturbances. This would include species used by the Lane Mountain milk-vetch as nurse shrubs. Whether such disturbed habitats would remain suitable for the Lane Mountain milk-vetch is unknown. The thin, rocky soils that support Lane Mountain milk-vetch would be easily eroded by foot and vehicle traffic. The species generally does not occur on exposed bedrock, and so the Army concluded that areas of recurrent ground disturbance from training and operations activities would probably be eroded to the point of rendering them unsuitable for Lane Mountain milk-vetch (Army 2003, Chapter 5, p. 19).

The Army has presumed that, over time, there is a continuing turnover of individual Lane Mountain milk-vetch plants as established plants die and seeds disperse and become established in new, unoccupied “microsites” that provide these requirements. Military training activities that remove existing or potential nurse shrubs or change the depth of soil by erosion or deposition are likely to eliminate Lane Mountain milk-vetch habitat (Army 2003, Chapter 5, p. 27).

Increase in Wind Erosion of Soils and Dust Deposition: Eller (1977, p. 106), Thompson et al. (1984, p. 187), Sharifi et al. (1997, pp. 837-846), and Farmer (1993, p. 63) have indicated that varying amounts of dust settling on vegetation can block stomata, increase leaf temperature, and

reduce photosynthesis. Wind in the Fort Irwin area is a considerable force and has the potential to transport large amounts of dust and topsoil (Army 2003, Chapter 5, p. 7). Airborne dust generated by vehicles buried soil crusts, resulting in the death of their photosynthetic organisms (e.g., cyanobacteria and green algae) (Belnap et al. 2001, p. 56), and wind generates dust that can cover or abrade Lane Mountain milk-vetch plants and nurse shrubs. Dust deposition on Lane Mountain milk-vetch plants has been found to reduce shoot length, increase water stress, and reduce or eliminate reproductive output for established Lane Mountain milk-vetch plants (Wijayratne et al. 2005, p. 4). It may also affect the photosynthesis, transpiration, and growth of Lane Mountain milk- vetch plants and nurse shrubs, and ultimately the ability of these individuals to persist (Wijayratne et al. 2005, p. 4). Similarly, when dust is deposited on Lane Mountain milk-vetch nurse shrubs, this dust could be expected to adversely affects photosynthesis, other physiological processes, and the growth of nurse shrubs.

Military training and operations activities that destroy desert shrubs and soil crusts or change the depth of the soil by erosion or deposition are likely to eliminate habitat elsewhere for the Lane Mountain milk-vetch by increasing the potential for increased wind erosion. This potential increase in wind erosion may result in an expanded zone of degradation and desertification of the landscape downwind from the site of the training activities (Army 2003, Chapter 5, p. 24). Okin et al. (2001, p. 135) studied this process at Fort Irwin and reported that disturbance resulting in the destruction of soil crusts and vegetation cover (such as military training activities) can cause indirect disturbance of adjacent areas. This occurs by: (1) transport of sand from disturbances resulting in deflation of the disturbed surface; (2) mobilization of dust and plant litter by wind, depleting the soils of nutrients in areas of direct disturbance; (3) damage to and burial of plants by saltating (leaping) sand in adjacent downwind areas; and (4) reduction of vegetation cover downwind, leading to an expanding area in which wind removes dust and litter material, depleting the soils of nutrients. Exposure of the soil to wind erosion, and the ensuing aeolian transport of dust and sand furthers the destruction of vegetation and soil crusts, ultimately reducing the fertility of the soil and its ability to support desert scrub vegetation. For the Lane Mountain milk-vetch, even if the impact from military training and operations activities can be located outside of its habitat, the species and its habitat (e.g., nurse shrubs) can be degraded and buried if located downwind from the source of the sand and dust.

Areas most likely to be affected by increases in dust levels include the Brinkman Wash/Montana Mine and Goldstone populations of the Lane Mountain milk-vetch due to their proximity to primary training corridors. Much of the Brinkman Wash-Montana Mine population is within a designated battle corridor that would be used primarily in force-on-force training exercises, and would have a high degree of exposure to windblown sand and dust generated by training activities (Army 2003, Chapter 5, p. 27). In contrast, the Goldstone population is upwind of training activities most of the time (Army 2003, Chapter 5, p. 27). Much of this population is uphill and may be shielded by topography, which may intercept blowing sand and dust. The Goldstone population would be less likely to be indirectly impacted by fugitive dust and soil movement (Army 2003, Chapter 5, p. 27).

Disruption of Pollination Systems: As stated in the Species Biology and Habitat Characteristics sections, we know little about the ecological needs of Lane Mountain milk-vetch pollinator and seed disperser species; therefore, we have little direct knowledge of the impacts of

military training and operations activities to these species. In their analysis of effects on the Lane Mountain milk-vetch, the Army assumed that military training and operations activities that remove vegetation or cause the erosion or transport and re-deposition of soil could disrupt ecological relationships with pollinators and seed dispersers. If military training in high- and medium-use areas in and adjacent to Lane Mountain milk-vetch populations results in the loss of most of the woody native vegetation in these areas, as it has in other areas of Fort Irwin with similar training levels, this loss would substantially reduce or eliminate the availability of flowers to support pollinators in these areas. This effect would reduce the number of pollinators for Lane Mountain milk-vetch within and between these populations. Reduced pollination would result in reduced seed production. Depending on the size and intensity of the area affected by military training, there could be a loss of these functions in much of the Paradise Valley and Brinkman Wash-Montana Mine populations of Lane Mountain milk-vetch and areas between these populations. For example, training activities that reduce local populations of Lane Mountain milk-vetch may indirectly disrupt pollination or seed dispersal “services” as the behavior of animals that perform these services may change in response to local plant densities and other factors (Army 2003, Chapter 5, p. 25). Based on Walker and Metcalf’s (2008b, p.170) results, which suggested that Lane Mountain milk-vetch is a facultative outcrosser that relies more on outcrossing in areas of high plant density and less in areas of low plant density, the disruption of pollinator services may lead to reduced levels of reproduction, recruitment, and genetic diversity of Lane Mountain milk-vetch plants.

Spread and Increase of Nonnative species/Competition: Wheeled and tracked vehicles also inadvertently transport seeds and plant parts from invasive nonnative plants from other locations to Fort Irwin. Because each rotational unit ships its own vehicles and equipment to Fort Irwin for training activities, each rotation has the potential to introduce nonnative plant parts and seeds to Fort Irwin every few weeks. Once at Fort Irwin, the roads, trails, and tracks would act as dispersal corridors for invasive nonnative plant species (Lovich and Bainbridge 1999, p. 313). Krzysik (1994b, p. 28) reported that Schismus, an annual grass native to the Mediterranean region, is ubiquitous at Fort Irwin; it represents the major component of ground cover in sandy, heavily used training areas. This ongoing introduction and dispersal mechanism results in the continued threat and likelihood of establishment of invasive nonnative species that now compete with the Lane Mountain milk-vetch and nurse shrubs for limited resources in the Mojave Desert, such as water and nutrients.

Change in Vegetation Type: Disturbance from vehicle and foot traffic and/or equipment use such as during military training can lead to changes in the native vegetation community type over time. As discussed above, surface disturbance may damage or remove nurse shrubs and their habitat, alter soil crusts and soil stability, increase soil loss, and open areas for colonization by invasive nonnative species. Over time, the successful establishment of invasive nonnative vegetation can choke out native vegetation and eventually dominate large areas (Army 2003, Chapter 5, p. 28). This altered disturbance regime may affect the habitat to the point beyond which native plant species are adapted and may result in large-scale vegetation community changes and ecosystem-level transformations (Mack and D’Antonio 2003, p. 723). These changes would reduce or eliminate the presence of nurse shrubs thereby reducing or eliminating habitat for the Lane Mountain milk-vetch.

Reduction in Seed Availability and Disruption of Seed Dispersal: The Army plans to conduct military training and operations activities in areas that partially overlap one and completely overlap another Lane Mountain milk-vetch population. High use training activities are planned on the northeastern portion of the Paradise Valley population and low- to medium use training activities on the Brinkman Wash-Montana Mine population. Training activities within these delineated areas of the two populations would reduce and may eventually eliminate Lane Mountain milk-vetch plants and nurse shrubs from these areas, resulting in a reduction in flower and seed production (See Fruit and Seed Production). Reduced seed production would mean a reduction in seed availability for germination and recruitment of new Lane Mountain milk-vetch plants.

In addition, the Army plans to conduct high use training activities in the areas between the Paradise Valley, Brinkman Wash-Montana Mine, and Goldstone populations (Army 2005, Chapter 2 p. 3; see Figure 6). Military training and operations activities would likely reduce or curtail the dispersal of seeds between these populations of Lane Mountain milk-vetch. Recall that lower densities of potential nurse shrub species in creosote bush-dominated communities occur between Lane Mountain milk-vetch populations and have inter-shrub distances too great to support Lane Mountain milk-vetch seed dispersal from wind or water between populations, effectively blocking expansion of the species (Prigge et al. 2011, p. 185). In addition, this creosote bush community is likely used as cover, forage, and dispersal habitat by animals that disperse Lane Mountain milk- vetch seeds (e.g., ants, small mammals, birds). These animal vectors and the habitats would be present in reduced numbers or would not be present and their reduction or absence would mean reduced movement of Lane Mountain milk-vetch seeds between these three populations.

Increase in Fire Frequency, Size, and Intensity: Another potential impact of military training and operations activities is increased fire ignition sources (BLM 2003, p. 32), such as campfires, cigarettes, and vehicles, which can result in fires that destroy Lane Mountain milk- vetch plants and habitat.

Historically, fire did not occur frequently in the Mojave Desert (Brooks and Matchett 2006, pp. 148–149). When fires occurred, they were ignited by natural sources such as lightning, and the fires were generally small in area because the interspaces between desert shrubs did not have sufficient fuel from native annual plants to carry and sustain a fire (Fenstermaker 2012, p. 1). Thus, native plant species in the Mojave Desert, including Lane Mountain milk-vetch and species used as nurse shrubs, are not adapted to fire because they have not evolved in an environment where the presence of fire was normal.

With the increasing human presence and activity in the desert and recent and ongoing introduction and proliferation of invasive nonnative annual plants in the Mojave Desert (e.g., red brome (Bromus madritensis), cheatgrass (Bromus tectorum), and Mediterranean grass (Schismus arabicus and S. barbatus) (Brooks and Matchett, 2006; p. 149)) fire frequency, intensity, and size have increased (Army 2003, Chapter 4, p. 14; Chapter 5, p. 7). Increased fire frequency is occurring from increased fire ignition sources from human activities in the desert such as military training and operations activities. The annual number of fires increased significantly between 1980 and 1995 (Brooks and Esque 2002, p. 334). Increased fire intensity and size has been attributed to the recent increase in invasive nonnative annual plant species numbers and densities. These invasive plants create a blanket of dried vegetation in the interspaces between

shrubs especially in years with above normal precipitation. The introduction and spread of invasive nonnative species provide fuel that carries fire across the desert landscape in the Mojave Desert (Brooks 1999, p. 16) and burns larger areas than documented historically. In 2005, fire burned more than 435,000 ac (176,039 ha) of Mojave Desert vegetation. This fire was fueled and carried by dense stands of invasive nonnative annual vegetation produced earlier in the year from of a wet winter and spring (USGS accessed 2012 http://www.werc.usgs.gov/Project.aspx?ProjectID=94).

Besides destroying the aboveground portions of plant species native to the Mojave Desert, fire also kills biological organisms at the soil surface and the top 2 in (5 cm) of the soil profile including plant roots, seeds, insects, and organisms that compose the soil crusts (Fenstermaker 2012, p. 2). Such fires would kill Lane Mountain milk-vetch plants, nurse shrubs (Army 2006, p. 91), and probably seeds and pollinators. Restoration of the vegetation community to its previous condition would take many decades if not longer or may not occur. An increase in wildfire frequency encourages establishment of invasive nonnative species, as they are quicker and more capable of re-establishment after fire. If they become established in the area, invasive nonnative species could potentially expand into, and ultimately displace native desert shrub communities damaged or destroyed by fire creating a vegetation type conversion (Brooks and Esque 2002, p. 330), thereby displacing the Lane Mountain milk-vetch and nurse plants and causing fragmentation.

Fragmentation and Reduction/Loss of Connectivity: Three of the four Lane Mountain milk-vetch populations are susceptible to fragmentation from the direct loss of plants and nurse shrubs from military training and operations activities. These populations are also susceptible to fragmentation from destruction of soil structure and disruption of soil function; increased wind erosion of soils and dust deposition; disruption of pollination systems; spread and increase of nonnative species; change in vegetation type resulting in loss of nurse shrubs; reduction in seed availability and disruption of seed dispersal; and increased fire frequency, size, and intensity.

Reduced Gene Exchange or Genetic Isolation: The factors that contribute to disruption of pollination systems, reduction in seed availability and disruption of seed dispersal, and fragmentation and reduction/loss of connectivity between populations of Lane Mountain milk- vetch also lead to reduced exchange of genetic material within and between populations. Small population size, few populations, and/or isolated populations are vulnerable to extirpation from random genetic, demographic, or environmental events and subject to genetic drift.

Summary of Effects from Military Training and Operations Activities

In summary, military training and operations activities planned for Fort Irwin’s Western Expansion Area may result in the loss of a substantial numbers of Lane Mountain milk-vetch plants and areas of habitat (BLM et al. 2005, Chapter 4, p. 73) from both direct and indirect impacts (Army 2003, Chapter 5, pp. 22–27). More than 6,660 ac (2,695 ha) of habitat containing Lane Mountain milk-vetch plants would be affected by military training and operations activities (Army 2003, Chapter 5, p. 25) (see Table 7). Impacts include the crushing or uprooting of Lane Mountain milk-vetch plants and nurse shrubs; crushing and burying milk-vetch seeds; disturbing soils; altering surface hydrology; promoting aeolian erosion and/or deposition of sand and dust;

and degrading or disrupting ecological relationships with predators, seed dispersers, pollinators, and competitors (invasive nonnative species). Cumulatively, these activities can result in long-term adverse impacts to Lane Mountain milk-vetch populations through increases in fire frequency, size, and intensity; changes in vegetation types including loss of nurse shrubs; fragmentation and reduction/loss of connectivity between populations; reduced gene exchange or genetic isolation, and reduced population persistence or greater vulnerability to random events (Army 2003, Chapter 5, p. 26).

Table 7. Estimated degradation to, or destruction of, Lane Mountain milk‐vetch plants and habitat from direct impacts1 from military training and operations activities. Only data for the three populations within the Fort Irwin boundary are included. [From Army 2003 and Service (Waln) 2012 October 30] Area of Percent of Percent of Population Species’ Area of Percent of Population Population Directly Habitat Population Species’ Directly Name Disturbed or Directly (ac ( ha) Habitat Disturbed or Eliminated Disturbed or Eliminated (ac (ha) Eliminated Goldstone 1,283 (519) 6 0 0 0 Brinkman Wash/ Montana 5,498 (2,225) 26 5,4982 (2,225) 100 26 Mine Paradise Valley 4,795 (1,490) 23 1,121 (456) 23 5 Coolgardie 9,778 (3,957) 46 03 0 0 Mesa Total 21,354 (8,641) 100 6,619 (2,679) --- 31 1 Indirect impacts are not presented; they are discussed in the text. 2 In this estimate, we assume the entire population could be lost over time because military activities are allowed in the entire population area except for tracked vehicles. 3 The Coolgardie Mesa population is located outside Fort Irwin.

Within the no-use areas of the Goldstone and Paradise Valley populations (that comprised about 4,500 ac (1,821 ha), we expect few to no direct impacts from military training and operations activities to the Lane Mountain milk-vetch and its habitat. Because these areas are not designated for military training and operations activities, these areas are administratively protected from the direct impacts of these activities. However, these conservation areas are signed but not fenced and are bordered by areas designated for high- and medium-use training, and may be subject to the occasional straying of vehicles and soldiers during training and operations activities. In addition, because of their proximity to medium and high use areas, the Lane Mountain milk-vetch and its habitat in the no-use areas of the Goldstone and Paradise Valley populations would be indirectly affected by military training and operations activities from wind erosion and dust deposition, disruption of pollination systems, spread and increase of invasive species, altered fire regimes, change in vegetation types, and fragmentation. The military training and operations activities planned on Fort Irwin’s Western Expansion Area may result in the loss of a substantial numbers of Lane Mountain milk-vetch plants and areas of habitat; therefore, the BLM intended to manage the remaining habitat on BLM lands on the Coolgardie Mesa and the west side of the Paradise

Range on a reserve-level basis (BLM et al. 2005, Chapter 4, p. 73). However, the BLM has limited resources and regulatory authority to manage the populations on their lands at this level. Please see the Mining Activities and OHV Activities sections below for a description of how the BLM is currently managing Lane Mountain milk-vetch habitat on its lands.

Conservation Measures Implemented

The Army has implemented mitigation measures for the Lane Mountain milk-vetch, both within Fort Irwin and the NTC and on nearby Lane Mountain milk-vetch habitat, to help offset the impacts from the proposed military training and operations activities in the Western Expansion Area. These measures include: (1) Designating areas within the Goldstone, Brinkman Wash-Montana Mine, and Paradise Valley populations of the Lane Mountain milk- vetch as unsuitable for some or all types of military training and operations activities; (2) purchasing private lands within the Paradise Valley and Coolgardie Mesa populations to be managed for the conservation of the species; and (3) helping the BLM, if needed, to make closed roads in the Coolgardie Mesa population area less accessible by fencing them or obliterating their view (e.g., vertical mulching).

Regarding the designation of areas as unsuitable for some or all military activities within the Lane Mountain milk-vetch populations on Fort Irwin, the Army designated three areas: (1) The NTC-Gemini Conservation Area; (2) the East Paradise Conservation Area; and (3) the Brinkman Wash Restricted Access Area (see Regulations section, Department of the Army). The first two areas are off limits to military training. In the Brinkman Wash Restricted Access Area (also called the No Dig Zone), military training is allowed, but vehicles are restricted to roads and staging or digging are prohibited. There is no restriction on foot soldier use. When military training and operations activities commence, the Army would manage these three areas at varying levels to avoid or reduce direct impacts to the Lane Mountain milk-vetch and its habitat. These areas overlay 6,255 ac (2,531 ha) or 29 percent of the known Lane Mountain milk-vetch population areas and habitat while leaving 5,321 ac (2,153 ha) or 25 percent available to military training and operations activities.

The NTC Gemini Conservation Area: This Conservation Area is approximately 2,481 ac (1,004 ha) and is located in the NTC along the southern boundary of the Goldstone Complex. This Conservation Area overlays approximately 88 percent of the Goldstone population of the Lane Mountain milk-vetch or 1,124 ac (455 ha). The remaining 12 percent or 159 ac (64 ha) of the Lane Mountain milk-vetch Goldstone population is located in the NASA Goldstone Complex leased by the Army to NASA for deep space communications and tracking facilities.

The NTC Gemini Conservation Area is an off-limits area to military training activities. The Army signed and fenced the Conservation Area boundary in 2003 to help restrict most military vehicle traffic in this Conservation Area (Fort Irwin INRMP 2005, pp. 91–92; Everly 2013 in litt. p. 1 6-20-2013), although a tank trail constructed in 1985 bisects most of the Goldstone Complex. Military training maneuvers do not occur here and wheeled vehicles or tanks use a tank trail because of potential dust interference with NASA’s research at the Goldstone Complex (Charlton 2007, p. 29). As a result, the Lane Mountain milk-vetch and its habitat within the Goldstone Complex, although outside the NTC Gemini Conservation Area, are essentially protected from the direct impacts of military training and operations activities.

Potential impacts on portion of Goldstone population in NTC

The impacts to the Lane Mountain milk-vetch plants and habitat in the NTC-Gemini Conservation Area and Goldstone population in the Goldstone Complex from military training and operations activities would be minimal. Milk-vetch plants and habitat in this Conservation Area would not be impacted directly by military training and operations activities except from accidental straying of military vehicles or soldiers from adjacent training use areas. Otherwise, the Army expects no direct loss of individual Lane Mountain milk-vetch plants or habitat. Because this Conservation Area is bordered by medium-use areas, it would be subject to indirect effects from military training and operations activities, which may result in the loss of some Lane Mountain milk-vetch individuals and habitat located near active use areas (Army 2003, Chapter 5, p. 24). Military training Areas B1 and B2, located immediately south and east of the NTC Gemini Conservation Area, are used for squad exercises rather than brigade-level mechanized training. Consequently, indirect impacts to individual Lane Mountain milk-vetch plants and habitat in the NTC Gemini Conservation Area, such as dust generation and reduction in pollinator and seed dispersing animals are presumably less than that generated in most Fort Irwin training areas with greater numbers of vehicles, equipment, and soldiers (Hessing and Shaughnessy 2011, p. 31).

East Paradise Conservation Area: The Army’s second conservation area, the East Paradise Conservation Area, is 4,302 ac (1,741 ha) and overlays 68 percent of the Paradise Valley population of the Lane Mountain milk-vetch. It is located along the southwestern boundary of the Western Expansion Area. The Army fenced the northern and eastern boundaries of the East Paradise Conservation Area with barbed wire. They have erecting signs around the southern and western boundaries of the East Paradise Valley Conservation Area to inform those entering from BLM land that this area is off limits and maintain these signs on a quarterly schedule (Everly in litt. 2013-6-20, p.1).

Extent of future impacts within the East Paradise Conservation Area

The Lane Mountain milk-vetch and its habitat in this area would not be directly impacted by military training and operations activities except on an accidental basis when military vehicles or soldiers stray into the area. Because this Conservation Area is bordered by medium- and high-use areas, it would be subject to indirect impacts from military training and operations activities, which may result in the loss of some Lane Mountain milk-vetch individuals and habitat located near active use areas (Fort Irwin BA).

About 32 percent of the Paradise Valley population within the Fort Irwin boundary is outside this Conservation Area and is subject to military training and operations activities. According to Army (2005, Chapter 2, p. 3), this 32 percent of the population is within an area designated as high and medium use for military operations and training activities. The Army anticipates that 60 to 100 percent of the Lane Mountain milk-vetch plants and habitat in this area would be lost over time from the high and medium use military training and operations activities (Army 2003, Chapter 5, pp. 23–24).

Brinkman Wash Restricted Area: A third area, the Brinkman Wash Restricted Access Area or No Dig Zone, is 1,872 ac (756 ha) or 51 percent of the Brinkman Wash-Montana Mine population of the Lane Mountain milk-vetch. In this area, access is restricted and non-combat ground disturbing activities, including the construction of small communication towers or observation decks, would be allowed (Fort Irwin INRMP 2005, pp. 88 and 92). This is considered a low use area (Army 2005, Chapter 2, p. 3). Habitat disturbance on the remaining 49 percent of this Lane Mountain milk-vetch population is unrestricted (Army INRMP 2005, p. 92) and is considered a high use area (Army 2005, Chapter 2, p. 3). As of 2009, the Army had erected conservation signs around most of the Brinkman Wash Restricted Access Area boundary (Hessing 2009, p.1). In addition, the southern boundary of the Brinkman Wash Restricted Access Area is fenced with barbed wire and the perimeter is signed. The signs and fences are physically checked on a quarterly basis and repaired and replaced as needed (Everly in litt, 2013- 6-20, p. 1). Future plans include erecting signs around the southwestern boundary of the Brinkman-Wash Restricted Access Area (Hessing 2009, p.1).

Table 8. Populations of Lane Mountain milk‐vetch on Fort Irwin that are open, restricted, and closed to military training and operations activities (Army 2003, Chapter 5, p. 25). Percent of Total Number of Polygon Size in Acres Population Area of Polygons Individual Plants (Hectares)1 Located 0/ 0 1,283 ac/ 519 ha 100 Goldstone 1,283/ 519 0 percent percent Montana Mine/ 14,360 ac/ 1,764 0 ac/0 ha 5,499/ 2,225 Brinkman Wash 79 percent 0 percent 1,543 ac/ 624 ha 3,419 ac/ 1,940 ha Paradise Valley 4,795/ 1,940 32 percent 71 percent 5,903ac/ 2,388 ha 4,702 ac/ 2,459 ha Total 11,577/ 4,684 51 percent 41 percent 1 Of the 4,360 ac directly impacted, 2,652 ac are in a high use area, and 1,707 ac are in a medium use area. The low use and “No Dig Zone.” areas (about 1,800 ac) are not considered in this table.

Extent of future impacts

The Army reports that in high use areas, frequent and intense training activities could ultimately impact, and cause the loss of, up to 100 percent of the habitat and individuals of Lane Mountain milk-vetch of the Brinkman Wash-Montana Mine population. This assessment of future impacts is based on studies at similarly used areas on Fort Irwin; they are degraded to the point that they retain little vegetative cover (Army 2003, Chapter 5, p. 23). As stated above individual Lane Mountain milk-vetch plants and some habitat may remain undisturbed in some of the low use Restricted Access Area (Army 2003, Chapter 5, p. 24) from direct impacts because the level of ground disturbing activities would not be at the level of force-on-force brigade training. However, this Restricted Access Area is bordered by medium and high use areas, so the Lane Mountain milk-vetch plants and habitat in the Restricted Use Area would also be subject to indirect effects from military training and operations activities. The indirect effects may result in the loss of some Lane Mountain milk-vetch individuals and habitat located close to active use areas (Chapter 5, p. 24). In addition, the Army cannot guarantee that medium- and low-use areas will not be 100 percent impacted and have a resultant 100 percent loss of individuals and habitat over time as no protection or restrictions are slated for these use areas (Army 2003, Chapter 5, p. 25).

With the designation of the two Conservation Areas and the Restricted Use Area within the Fort Irwin and Western Expansion Area boundary, about 22 percent of the four Lane Mountain milk-vetch populations and habitat would be conserved or the impacts restricted. However, this amount is a best case scenario as it assumes there would be no indirect impacts from adjacent military activities to these areas.

Table 9. Relationship of Lane Mountain milk‐vetch populations within Fort Irwin boundary to the Army’s Two Conservation Areas and One Restricted Area (“No Dig Zone”). Population Percent of Population Percent of Army’s Area Population Area Army’s Population Conservation inside Army inside Army outside Army Population Conservation outside Army Population Area/ Conservation Conservation Conservation Area Area/ Conservation Name1 Restricted Areas/ Areas/ Areas/ ac (ha) Restricted Areas/ Area Restricted Restricted Restricted Area Name Restricted (ac (ha)) Area Area Area Area (ac (ha)) (ac (ha)) NTC Gemini 1,283 2,481 Goldstone Conservation 1,124 (455) 88 159 (56) 12 (519) (1,004) Area Brinkman Brinkman Wash- Wash/ 5,498 Montana 3,753 3,619 1,879 (760) 34 66 Montana (2,225) Mine (1,519) (1,465) Mine Restricted Area East Paradise Paradise 4,795 4,302 3,252 Conservation 68 1,543 (624) 32 Valley (1940) (1,741) (1,316) Area 11,576 8,656 6,255 5,321 Total ------54 46 (4,685) (3,503) (2,531) (2,153) 1Coolgardie Mesa population is not included because it is outside Fort Irwin.

Land Acquisition

Several parcels of private land were located within the Western Expansion Area. The Army purchased all non-Federal lands, including lands identified as Lane Mountain milk-vetch habitat, in the Western Expansion Area. The purchases were completed to ensure that no private lands remained within the Western Expansion Area boundary of Fort Irwin. The lands purchased included about 2,000 ac (809 ha) of private land as part of the Army’s East Paradise Conservation Area. The East Paradise Conservation Area is approximately 4,302 ac (1,741 ha) or 80 percent of the Paradise Valley population of the Lane Mountain milk-vetch.

To reduce threats to and help manage for the Lane Mountain milk-vetch and its habitat outside Fort Irwin, the Army also purchased most of the private lands within the boundaries of the BLM’s West Paradise and Coolgardie Mesa Conservation Areas. Land acquisition in this area was about 2,560 ac (1,036 ha) (Service 2013c, attachment). The Army did not acquire mineral rights and water rights as part of the land purchase; thus, these lands are still available for these types of exploration and development. The Army intends to transfer these lands in the future to the BLM to be managed as part of the BLM’s Coolgardie Mesa and West Paradise Conservation Areas for the Lane Mountain milk-vetch, but the date of this planned transfer is unknown. However, the Army will retain three parcels that overlap the Army’s Manix Tank Trail (Everly 2012 in litt., August 8, 2012). The Manix Tank Trail provides military access to Fort Irwin from Interstate 15. The Manix Tank Trail is made up of a series of dirt roads and trails that extend from the Manix railhead on the Union Pacific Railroad next to Interstate 15 and east of Barstow, northwest onto Fort Irwin and the Western Expansion Area. The Army uses the Manix Tank

Trail to transport visiting training units’ equipment to and from Fort Irwin for military training exercises (Army SFEIS 2005, Chapter 3, p. 162).

The Army has also offered to contribute to the BLM’s efforts described in the West Mojave Plan to close roads and rehabilitate disturbed areas within the BLM’s Coolgardie Mesa Conservation Area boundary. These efforts may include fencing in appropriate locations, if required (Army 2003, Chapter 5, p. 24). We have no information that the BLM has accepted and implemented this offer.

Summary of Conservation Measures Implemented

In summary, the Army has implemented conservation measures that are intended to offset the impacts of the Army’s expansion of Fort Irwin and increased areas of military training and operational activities in the Western Expansion Area. These measures include the Army designating and managing more than 4,376 ac (2,940 ha) of Lane Mountain milk-vetch habitat as Conservation Areas, thus avoiding and reducing impacts, and the acquisition of about 2,550 ac (1,032 ha) of private lands outside of the boundaries of Fort Irwin, which contain Lane Mountain milk-vetch plants and habitat to help compensate for impacts. These conservation measures have placed 20.5 percent of the known Lane Mountain milk-vetch plants and habitat into Conservation Areas that are off-limits to the direct impacts of military training and operations activities.

Mining Activities

At the time of listing we identified destruction of Lane Mountain milk-vetch plants and habitat from dry wash gold mining, other mining activities (materials lease mining), and rock and mineral collecting as threats to the Lane Mountain milk-vetch (63 FR 53597). We noted that the proximity of the Lane Mountain milk-vetch’s Coolgardie Mesa population to active mining areas in the Coolgardie mining district make it vulnerable to unplanned, potentially destructive, human activities associated with mining.

In the 5-year review, we identified surface mining activities as a continuing threat to the Lane Mountain milk-vetch and its habitat. With high mineral potential, the Coolgardie mining district, which overlaps much of the Coolgardie Mesa population of the Lane Mountain milk- vetch, is laced with historical mine pits, and mining clubs hold current mining claims for much of the area. These clubs engage in small-scale recreational gold mining that for individual mining claims probably has a minor effect on the Lane Mountain milk-vetch and its habitat, but cumulatively, the effects of such surface disturbance from all claims and several clubs including exploration activities are much greater (see Figure 8).

History of Mining in the Coolgardie Area

The Coolgardie Mining District was established in the early 1900s. Miners have worked this area for more than a century. Gold, the primary mineral, is found mostly as tiny particles in the upper few feet of alluvial soil from placer deposits (BLM et al. 2005, Chapter 3, p. 237). The Coolgardie Mining District, located about 15 mi (24.1 km) north of Barstow and overlaps the

Coolgardie Mesa population of the Lane Mountain milk-vetch (BLM et al. 2005, Chapter 3, p. 237). The Coolgardie Mesa population is laced with historical exploratory mine pits (Service 2008, p. 10). There are a few buildings left at an historical mining camp, the Kinney camp, 0.5 mi (0.8 km) west of the Coolgardie Mesa Conservation Area (BLM et al. 2005, Chapter 3, p. 237; Calif. Div. of Mines and Geology 1976, p. 1). In addition, there has been a history of mining for other materials including decorative rock and zeolites (Griffith 2013 in litt., Attachment 2, p. 1). The known mining locations are in the mountains that border the Coolgardie Mesa population of the Lane Mountain milk-vetch.

Figure 8. Locations of past and current mines and mineral potential with respect to the location of Lane Mountain milk‐vetch populations.

Description of Mining Activities within the Range of the Lane Mountain Milk-vetch

Mining activity includes accessing the mine site by vehicle(s), transporting equipment from the vehicle(s) to the excavation sites(s), excavating and processing the material, and hauling it offsite for sale. Other activities associated with mining include establishing a temporary (e.g. camper or motor home) or permanent residence (e.g., trailer). Accessing the mine site, transporting equipment from the vehicle(s) to the excavation site(s), and hauling it offsite for sale will be discussed under OHV Activities.

Current mining activity in the Coolgardie Mining District is mostly for gold, but other minerals, such as pumice, perlite (a non-crystalline volcanic glass used in building products, filters, and horticulture), decorative rock, silver, copper, tungsten, and zeolite have been discovered or mined in the area (Griffith 2013, Attachment 2, p. 1). Within the Coolgardie Mesa Conservation Area, most mining activity is recreational gold mining or exploratory mining.

Mining activity on BLM lands is directed by the Mining Laws of 1872 and implementing regulations. The BLM is the agency responsible for implementing these laws and regulations on all Federal lands (see Regulatory Mechanisms). The laws and regulations applicable to mining vary with the type and scale of mining activity. In general, the activity levels and respective notification levels are casual use mining, filing and maintaining a mining claim, and filing a mining plan of operation.

According to the BLM, “casual use” mining includes those activities, such as mineral collecting or small-scale placer operations, that have no or a negligible effect on public resources. Casual use generally includes the collection of geochemical, rock, soil, or mineral specimens using hand tools, hand panning, or non-motorized sluicing. It may include use of small portable suction dredges. It also generally includes the use of metal detectors, gold spears, and other battery-operated devices for sensing the presence of minerals, and hand and battery- operated drywashers. Operators may use motorized vehicles for casual use activities provided the use is consistent with the regulations governing such vehicle use (43 CFR 8340-8343), off- road vehicle use designations contained in BLM land-use plans, and the terms of temporary closures ordered by the BLM. The BLM is not obligated to provide access to casual use mine locations. Casual use miners must stay on designated open routes of travel (Jamie Livingood 2013 in litt. p. 1).

Casual use mining can occur anywhere on BLM land in the California Desert Conservation Area that is not withdrawn from mineral entry or has a valid mining claim held by another party. Casual use miners may continue to mine as long as they fill in their pits and the cumulative disturbance does not cause more than “negligible” disturbance (BLM et al. 2005, Chapter 3, p. 237). For example, the BLM may consider mining activities that do not use earthmoving equipment or explosives as casual use (BLM 2011, p. 23). The BLM does not require casual use miners to notify them or obtain approval prior to conducting their activities (BLM et al. 2005, Appendix P, p. 1542).

Mining activity to establish and maintain a mining claim has specific requirements. The BLM requires the claimant to locate a mineral deposit on BLM land with no existing claim, to

file a claim that gives the claimant the right to develop and extract the mineral deposit, and to maintain the mining claim with either annual maintenance activities (e.g., improving routes to the mining claim, conducting assessment work using hand tools or heavy equipment, etc.) filed as a notice to the BLM, or the payment of a $140 annual fee per claim (BLM 2011 pp. 2, 7, and 8; Jamie Livingood 2013, pers. comm.). Each mining claim is a maximum of 20 ac (8 ha) per person to a maximum of 160 ac (65 ha) per association with eight or more persons (BLM 2011, p. 8).

For mining operations greater than 5 ac (2 ha) on a mining claim, the BLM requires that a plan of operation be submitted to BLM prior to implementation. The plan should include measures to reclaim the site once mining operations have ceased. Restoration of the site is not required. In the two Lane Mountain milk-vetch Conservation Areas, a notice or plan must be filed with the BLM for any mining activity greater than casual use because it is an Area of Critical Environmental Concern (ACEC).

Location of Mining Activities with Respect to the Lane Mountain Milk-vetch and Its Habitat

Land ownership in the Coolgardie Mining District and Coolgardie Mesa area is BLM, Army, private, and State with most of the land managed by the BLM. This area is popular for casual use mining because of the placer deposits of gold.

There is evidence of historical mining activity on BLM lands in the Coolgardie Mesa Conservation Area. BLM information on these activities is limited to knowing that there are shafts in this Conservation Area and three have been “rehabilitated” with the installation of bat gates. In addition, there are old structures/out buildings present in the Coolgardie Mesa Conservation Area associated with past mining activities.

The BLM considers much of the area of the Coolgardie Mesa population of the Lane Mountain milk-vetch as having high or medium mineral potential for metallic minerals, especially placer gold deposits (BLM et al. 2005, Chapter 3, p. 219). The Coolgardie Mesa area has 9,890 ac (4,002 ha) with high potential for metallic minerals and 1,806 ac (731 ha) with medium potential for metallic minerals (BLM et al. 2005, Chapter 3, p. 222). Thus, 74 percent of the area of the Coolgardie Mesa population of the Lane Mountain milk-vetch has high mineral potential and 14 percent has moderate potential. There is no estimate for the number of ounces of unrecovered gold for the Coolgardie mining district, but there is a persistent occurrence of placer gold covering an area of several square miles (Leszcykowski, et al. 1993, p. 43, as cited in BLM et al. 2005, Chapter 3, p. 222).

Currently there are three mines on private lands located south and southeast of the Coolgardie Mesa population of the Lane Mountain milk-vetch (Service 2013d, attachment). One mine is permitted but considered abandoned by San Bernardino County. A second mine is active and a third is newly permitted. The last two mines quarry decorative stone (Griffith 2013 in litt., Attachment 2, p. 1) These mines crush, sort, and size their product on site and use BLM open routes for access (see OHV activities (Griffith 2013 in litt., Attachment 2, p. 1).

On BLM lands in the Coolgardie Mesa and West Paradise Conservation Areas, there are no known active mines. In the West Mojave Plan, the BLM identified one active mine, Coolgardie Gold, on BLM land (BLM et al. 2005, Chapter 3, p. 230) and within the boundary of the Coolgardie Mesa population of the Lane Mountain milk-vetch. However, BLM was unable to confirm that this mine was currently operating (Jamie Livingood 2013, pers. comm.).

The BLM has approved nine mining plans of operation in these two areas. Of these, eight mining plans of operation have had their case files closed, meaning there should be no existing active or approved mining plans of operation at these locations and no mining activities other than casual use. The ninth mining plan of operation is a pending case file. The BLM has not received the required annual financial assurance from the claimant since 1994. The BLM is in the process of closing this file (Jamie Livingood 2013, pers. comm.).

Before the BLM can close a file, the mine site must be reclaimed. Depending on when the mine was initiated, the amount of reclamation that the BLM requires varies. For the oldest mines, these did not have a mining plan of operation and no reclamation was required. For mines with a mining plan of operation, the reclamation in the older plans frequently required backfilling trenches. Recent mining plans of operation may include more reclamation such as recontouring and reseeding. There was no mention of effectiveness monitoring.

There are several mining claims within the area of the Coolgardie Mesa population of the Lane Mountain milk-vetch (BLM et al. 2005, Chapter 3, p. 219). In 2001, the BLM had records of 22 placer mining claims within the Coolgardie Mesa population (BLM et al. 2005, Chapter 3, pp. 231, 237), with the heaviest concentration of these claims in the western portion of the population. Schulte (2005a, and 2005b, as cited in Service 2006, p. 166) reported that these 22 mining claims covered about 785 ac (318 ha) scattered among the Coolgardie Mesa population of the Lane Mountain milk-vetch.

Current BLM records indicate that there are seven active mining claims on file that cover 320 ac (129 ha) on BLM land in the Coolgardie Mesa Conservation Area (as of February 2013 Jamie Livingood 2013, pers. comm.). The location of all claims is within one section (Jamie Livingood 2013, pers. comm.). Of these seven mining claims, none has filed a mining plan of operation or notice with the BLM (Jamie Livingood 2013, pers. comm.).

Most mining in the Coolgardie Mesa Conservation Area is conducted by members of “mining clubs” that hold claims and that engage in small-scale recreational gold mining, or by “casual use” mining that occurs on BLM lands with no mining claims. Members of several recreational mining clubs frequent the area, with most activity conducted on weekends in the late spring and fall when the weather is not hot and the soil is dry. The larger clubs may have a membership of 400 families. During an average day in the gold dry-washing

season, the number of club members at a site may vary from 3 to 30 persons. However, on one weekend, the BLM recorded 300 to 400 people mining within a 1-square mi (2.5-square km) area (T. Egan, pers. comm. 1996). Activities include the use of both battery and gasoline-powered dry washers (BLM et al. 2005, Appendix P, p. 1545). In addition, most of the club mining on the Coolgardie Mesa Conservation Area is categorized as “casual use” by the BLM.

Prospecting for gold continues in the Coolgardie Mesa area. In 1993, the Coolgardie Mesa experienced a sharp increase in recreational gold mining. The BLM predicts that future mineral activity will be concentrated in the categories of gold (especially with a price increase) (BLM et al. 2005, Chapter 3, p. 229).

Effects of Mining Activities to the Lane Mountain Milk-vetch and Its Habitat

Type of impacts: The impacts to the Lane Mountain milk-vetch and its habitat from mining activities are similar to those described under Military Training and Operations Activities, though the area of impact from each mining claim or operation is smaller. Mining operations include surface disturbance from digging using hand tools and heavy equipment or other methods, burial from side casting, placement and use of equipment, repeated foot traffic in confined areas, and fugitive dust. These activities could impact the Lane Mountain milk-vetch directly by uprooting and burying Lane Mountain milk-vetch plants and nurse shrubs and burying Lane Mountain milk-vetch seeds; and indirectly affect the species and nurse shrubs by destroying the soil’s structure (including soil crusts) and disrupting soil function; altering surface hydrology; increasing wind erosion of soils and dust deposition; disrupting pollination systems; and spreading and increasing invasive nonnative plant species. These impacts contribute to changes in vegetation type; increases in fire frequency, size, and intensity; fragmentation and reduction/loss of connectivity; reduced gene exchange; and reduced population persistence (see Military Training and Operations Activities - Effects of Military Training and Operations Activities to the Lane Mountain Milk-vetch and Its Habitat).

Impacts from historical use: The Coolgardie Mesa is laced with historical exploratory mine pits. This information is important because an area with surface disturbance that involves digging destroys the soil’s structure and function to a deeper extent than from soil compaction. This greater degree of impact likely means the recovery of the soil’s structure and function will likely take centuries rather than decades, and that restoration of the area for the Lane Mountain milk-vetch and nurse shrubs will take even longer.

Impacts from current casual use mining activities on BLM lands: For mining clubs or recreational miners conducting casual use mining activities on BLM lands, the amount and extent of surface disturbance from one weekend’s work on a mining claim by a few recreational miners would likely be small. However, within a few miles of the Coolgardie Mesa population of the Lane Mountain milk-vetch, the BLM recorded 300 to 400 people mining within a 1 square mi (2.5 square km) area during one weekend. Joshua trees (Yucca brevifolia) and other woody vegetation were uprooted and destroyed in this process (T. Egan, pers. comm. 1996). The BLM responded by developing regulations (43 CFR 3809) to limit activities under the definition of “casual use” mining. Under the regulations, “casual use” mining is limited to the use of non- mechanized tools and cannot result in the direct destruction of perennial woody vegetation.

The extent of impacts from past and current casual use mining on Lane Mountain milk- vetch habitat is difficult to quantify. Casual use miners are self-regulating. Because there is no BLM oversight of casual use mining activities, there is no mechanism for monitoring and reporting the location and extent of compliance with the BLM’s regulations, or monitoring the direct and indirect impacts to Lane Mountain milk-vetch and its habitat. Under casual use, the BLM allows the excavation of mining pits and soil surface disturbance that degrade Lane Mountain milk-vetch habitat and impact Lane Mountain milk-vetch, plants, seeds, and nurse shrubs directly and indirectly.

Based on past and current practices, there is limited enforcement of BLM regulations and policies (see Regulatory Mechanisms). The BLM has seven rangers that patrol 3.2 million ac (12,9 million ha) of BLM land; the Coolgardie Mesa and West Paradise Conservation Areas are a small part of this area (USFWS 2013e. Email 2013-4-23 Summary of March 6, 2013 meeting with BLM). Their job is to educate the public and enforce applicable Federal laws and regulations on BLM lands .

The areal extent of all casual use mining activities and associated impacts on BLM lands to the Lane Mountain milk-vetch and its habitat have not been quantified because these activities are not monitored. Recalling that the BLM relies on the club members to police their individual activities, the BLM provided no documents that describe planned mining activities or completed activities (e.g., annual reports) for casual use mining on BLM lands in the Coolgardie Mesa area. Therefore, we found no information on the extent of impacts to Lane Mountain milk-vetch plants, nurse shrubs, or habitat in the Coolgardie Mesa population from these mining activities on BLM lands.

Cumulative effects: The cumulative effects of several mining clubs working their claims on weekends for several years can result in impacts that have more than a negligible effect on public resources including the Lane Mountain milk-vetch and its habitat. Although the BLM recently modified their casual use mining regulations, the BLM does not require restoration of casual use mining sites and does not monitor this activity to collect information on the total area impacted from this activity or its impacts to the Lane Mountain milk-vetch. Thus, it is unlikely that there is information on the areal extent of these activities over time. Because of the nature of the impacts (e.g., destruction of soil structure and disruption of soil function), it is unlikely that the Lane Mountain milk-vetch or its nurse shrubs will become established at casual use mining sites in the future.

Conservation Measures Implemented

The BLM recognized the importance of managing the remaining Lane Mountain milk- vetch plants and habitat on BLM lands in the Coolgardie Mesa and the west side of the Paradise Valley populations on a reserve-level basis (BLM et al. 2005, Chapter 4, p. 73). In 2005, the BLM designated the Coolgardie Mesa and West Paradise Conservation Areas and classified them as Areas of Critical Environmental Concern (ACECs). This area includes about half the known locations of individual Lane Mountain milk-vetch plants and about 45 percent of the habitat for the Lane Mountain milk-vetch.

West Paradise Conservation Area: This Conservation Area is 1,243 ac (503 ha). It is located along the western sliver of the Paradise Valley population of the Lane Mountain milk- vetch, and is contiguous with the Army’s East Paradise Conservation Area. According to the West Mojave Plan in 2005, land ownership in this Conservation Area contains BLM land (257 ac (104 ha) and private land (986 ac (399 ha)), and is contiguous with the Army’s East Paradise Valley Conservation Area along the southwestern boundary of Fort Irwin.

Coolgardie Mesa Conservation Area: This Conservation Area overlays 13,354 ac (5,404 ha) of the Coolgardie Mesa population of the Lane Mountain milk-vetch. According to the West Mojave Plan, in 2005 land ownership within this Conservation Area was BLM (10,107 ac (4,090 ha)) and private and Army (3,247 ac (1,314 ha)). We estimate the area on BLM land is about 9,322 ac (3,772 ha) in the Coolgardie Mesa Conservation Area (BLM et al. 2005, Table 2-31) and 257 ac (104 ha) in the West Paradise Conservation Area.

The BLM identified specific land management prescriptions in the West Mojave Plan that may apply to mining activities for the Coolgardie Mesa and West Paradise Conservation Areas including the following (BLM et al. 2005, p. 1540): (1) Conditioning use permits to avoid Lane Mountain milk-vetch plants: Prior to issuing any use permits, the BLM would require botanical surveys. No permits would be issued that allow “take” of the Lane Mountain milk- vetch (projects would have to be relocated) (BLM et al. 2005, chapter 2, p. 108); (2) notifying claimholders of the presence of the Lane Mountain milk-vetch; (3) developing restrictions on casual use mining that involves ground disturbance within the Coolgardie Mesa Conservation Area would be developed as necessary; and (4) withdrawing the two Lane Mountain milk-vetch Conservation Areas from future mineral entry (BLM et al. 2005 as cited in Service 2008, p. 10).

The first land management prescription discusses use permits. A use permit is a land use permit issued by the BLM for discretionary actions such as granting a right-of-way, temporary use permit, etc. It does not apply to mining because mining is not a discretionary action that requires issuing a permit on BLM land. To provide a mechanism to regulate mining activity in these two Conservation Areas, the BLM in the West Mojave Plan said that it would pursue a mineral withdrawal within the two Land Mountain milk-vetch Conservation Areas.

The second prescription, notifying claimholders of the presence of the Lane Mountain milk-vetch has not been formally done by BLM, that is, BLM has no record of it notifying claim holders (e.g., letters mailed). Because casual use mining can be conducted by anyone with no notification required to the BLM (casual use mining does not require a mining claim), BLM has no ability to identify all the casual use miners and inform them of the presence of the Lane Mountain milk-vetch.

The third prescription, developing restrictions on casual use mining, has occurred. Until recently, casual use mining included using heavy machinery (e.g., backhoes) in the Coolgardie Mesa Conservation Area. By regulation, the BLM now limits the activities under casual use mining to the use of hand tools and dry washers under 10 horsepower at the mining site. Although the BLM has sent letters to the seven active mining claimants informing them of the revised definition of casual use mining activities, it has no way to inform all casual use miners in

the two Lane Mountain milk-vetch Conservation Areas because casual use miners are not required to notify BLM of their activities.

Regarding the implementation of the mineral withdrawal that the BLM committed to doing in their 2005 West Mojave Plan, the BLM’s Barstow Field Office initiated the mineral withdrawal process in 2012 (J. Livingood 2012 in litt., September 13 email). As of December 2013, the draft withdrawal package, prepared by the Barstow Field Office, had been forwarded the Washington Office for review (Cynthia Staszak in litt. 2013 Email 2013-12-9 BLM CA State Office). Once completed, the BLM would then publish in the Federal Register a Notice of Intent to withdraw the two Conservation Areas from mineral entry and announcement of a public meeting. This is followed by a 2-year (or longer) evaluation process of the proposal including mineral assessment work and compliance with the National Environmental Policy Act that the BLM funds. The BLM would need to determine if a claimed area contains economically viable mineral deposits. If a claim does not contain economically viable mineral deposits, the BLM could deny an application to mine the area and extinguish the claim (J. Livingood, 2013, personal communication). With the limited budget and staffing in the BLM, this evaluation process may take longer.

Because this proposed mineral withdrawal is greater than 5,000 ac (2,023 ha), Congress must make the final decision to withdraw or not withdraw the area from future mineral entry. Thus, the congressional approval process may take several years before a final decision is made on a mineral withdrawal for these two Lane Mountain milk-vetch conservation areas, assuming that the proposal is not halted as it makes its way to Congress. Until the process is completed, all BLM lands in the Coolgardie Mesa and West Paradise Conservation Areas remain open to existing and new mineral exploration and development. If approved, a mineral withdrawal would not affect valid existing claims or unvalidated claims; the owners of these claims could continue to mine their claims.

Summary of Conservation Measures Undertaken

Conservation measures in areas outside Fort Irwin will depend on the success of the BLM’s implementation of measures described in the West Mojave Plan to manage the Coolgardie Mesa and the west side of the Paradise Valley populations on a reserve-level basis (BLM et al. 2005, Chapter 4, p. 73). However, most measures would not affect past or existing mining activities because they are not discretionary or they have not been implemented (e.g., mineral withdrawal). Therefore, all lands within the boundaries of the Coolgardie Mesa and West Paradise Conservation Areas remain open to mineral exploration, recreational mining, and commercial mining development and will likely remain open for several years.

Off-highway Vehicle (OHV) Activities

At the time of listing in 1998, we identified the loss and degradation of habitat from OHV use as a threat to the Lane Mountain milk-vetch. In the 5-year review, we continued to identify this activity as a threat, noting that OHV use had increased in one area of the Coolgardie Mesa population during the past 10 years, creating a barren area of approximately 20 ac (8 ha) where the Lane Mountain milk-vetch used to occur (Hessing, in litt. 2006). We also reported that OHV

vehicle use had increased in the area of the Paradise Valley population during this time (C. Rutherford, pers. obs. 2006). However, with the transfer of much of this land in the Paradise Valley population and Brinkman Wash-Montana Mine population to the Army, we predicted that unauthorized OHV use by the public on these Army lands in the Paradise Valley population would be reduced or eliminated. Below we describe the current and potential threats to the Lane Mountain milk-vetch from OHV recreational use.

Description of OHV Activities in the Range of the Lane Mountain Milk-vetch

Off-highway vehicle (OHV) use is any use that includes driving a motorized vehicle off a paved road, including driving cross-country or on a dirt road. About 18 percent of Californians participate in OHV use (BLM et al. 2005, Chapter 2, p. 161). Users of OHVs engage in many types of activities in the Mojave Desert. These can be categorized into two general groups: (1) when driving the vehicle is the recreational activity, and/or (2) when the vehicle is a means to access other forms of activities (BLM et al. 2005, Chapter 3, p. 246). Regarding the first category in the western Mojave Desert, there are four types of OHV recreational activities: (1) general vehicle tours using SUVs; (2) motorcycling and motorcycle events; (3) all terrain and “technical” four-wheel-drive recreation; and (4) competitive events (BLM et al. 2005, Chapter 2, pp. 246–248). Regarding the second category, examples of other activities in which OHV use is a means of access include driving an OHV to a specific destination such as a campsite or mine claim. The recreational activity is not the driving of the OHV itself; rather, it is used to access a site to conduct other activities (BLM et al. 2005, Chapter 3, p. 249) or the OHV driving may be conducted with other activities such as camping.

In the western Mojave Desert, the BLM manages its lands for OHV use including recreation. The BLM has designated existing dirt roads as either open to motorized vehicle use or closed. Open roads usually are indicated with a sign or marker that the road is open. This process is called route designation. In addition, the BLM has designated previously existing disturbed camping areas adjacent to routes as “open,” and motorized vehicle stopping and parking is allowed within 50 ft (15 m) of the centerline of routes designated as “open” (BLM et al. 2012, Chapter 2, p. 11). For any of the four types of OHV recreational activities, OHV use may be a group activity. Such group use usually includes the practice of assembling at staging areas or locations where people, vehicles, equipment, or materials are assembled before undertaking an activity. Staging areas are not authorized by the BLM unless they occur within the stopping and parking areas.

Not all members of the public comply with the BLM’s designations of open and closed roads. Some operate their vehicles on closed roads or off roads driving cross-country creating new unauthorized roads and staging areas. To deal with this lack of compliance, BLM has determined that the best program to implement to achieve compliance in designated route areas involves: (1) keeping open routes well signed; (2)revegetating and otherwise rehabilitating closed routes so that they are not visually apparent or easy to use; (3) maintaining a field presence of BLM personnel to contact and inform OHV users on BLM lands and enforce the law; and (4), establishing BLM-trained and supervised volunteer groups who assist in keeping the open routes signed and who can contact visitors to explain applicable use policies (BLM et al. 2005, Chapter 3, p. 249). Once the BLM has designated vehicle routes, the open routes need

to be maintained and monitored to keep users on those open routes and keep them from creating new unauthorized routes, staging areas, or driving cross-country. If open routes become too difficult to travel, recreational visitors would be more likely to use closed routes (BLM et al. 2005, Chapter 3, p. 249) or create new unauthorized routes. Closed routes would not be signed and would either be reclaimed naturally or vertically mulched. Due to monetary and staffing constraints, and the remoteness of much of the western Mojave Desert, most of the routes designated closed would be left to natural reclamation (BLM 2003 route designation, p. 20) that would take several decades or longer.

The primary recreation activities and other resource uses that use OHVs in this subregion are rockhounding, camping, picnicking, powerline and pipeline rights-of-way, mining and recreational mining, hunting, and OHV use (BLM et al. 2005, Appendix R, p. 1579). The BLM’s route network in the West Mojave Plan provides access to a various destinations in and near Lane Mountain milk-vetch habitat to conduct these recreational activities. Under the West Mojave Plan, BLM allows motorized vehicles to stop and park 50 ft (15 m) from centerline of a designated route in the Coolgardie Mesa and West Paradise Conservation Areas, and motorized camping in previously existing disturbed camping areas adjacent to open routes (BLM et al. 2005, Chapter 2, p. 235).

One of the most popular recreational activities in the Coolgardie Mesa area is recreational mining (BLM et al. 2005, Appendix R, p. 1580) (see Mining above). Before the Army acquired most of the private lands in the Coolgardie Mesa and West Paradise Conservation Areas, there was a patchwork of private and public lands in these Conservation Areas for the Lane Mountain milk-vetch that resulted in an incomplete network of access routes (BLM et al. 2005, Chapter 4, p. 74). Although the BLM may have wanted to close certain road segments in these Conservation Areas, they were unable to do this for those segments that provided access to private lands and mining claims.

The Coolgardie Mesa Conservation Area is crossed by numerous authorized or open and unauthorized or closed roads. We compared data on the number and locations of routes of travel in the Coolgardie Mesa Conservation Area from past and current data layers compiled by the BLM. This information shows that more roads exist now in these Conservation Areas than reported by the BLM in previous years. The BLM’s 1985-87 data reported 13.5 mi (21.7 km) of routes in the Coolgardie Mesa area, the 2005 West Mojave Plan reported 67.3 mi (108.3 km) (USFWS 2013e, . map ), and the BLM’s 2012 data layer showed 134 mi (216 km) of roads (USFWS 2013e, map2013f). These data indicate a doubling of routes present in the last 8 years and a tenfold increase in the last 25 years (see Figures 8 and 9).

In the southernmost portion of the Coolgardie Mesa Conservation Area, OHVs use has created large denuded areas that are used as staging areas by OHVs that spread out from these areas. Mark Hessing (pers. comm. 2004) noted that he has observed OHVs traveling through habitat of the Lane Mountain milk-vetch west of Copper City Road, the main dirt road through the Coolgardie Mesa population (Service 2006, p. 166 BO). Hessing reported that this activity contributed to the creation of a barren area of about 20 ac (8 ha) where Lane Mountain milk-vetch used to occur (Hessing, in litt. 2006). Charlton (2007, p. 29) reported that since the time of listing, unauthorized off-highway vehicle use had increased within the Coolgardie Mesa and Paradise Valley population areas. Although most of the increased use has been dispersed in nature, one area on the west side of Coolgardie Mesa population sustained a large increase in concentrated use.

In March 2013, Hessing reported to the BLM that there were several campers and off- road vehicles at Coolgardie Mesa, with a steady stream of campers headed in that direction. Many had posted signs pointing to their rendezvous locations with one sign from a commercial outfit giving rides. The sign was located near the large BLM sign instructing people not to ride in the area (Hessing 2013 in litt. March 15).

Location of OHV Recreational Use with Respect to the Lane Mountain Milk-vetch Populations and Its Habitat

OHV activity has been observed in habitat for the Lane Mountain milk-vetch on Army and BLM lands. Army lands are closed to public use, while BLM lands are open to the public for OHV use on designated open roads in the Coolgardie Mesa and West Paradise Conservation Areas. These two Conservation Areas are located in the Superior subregion. Numerous roads, mainly unimproved, crisscross this subregion. Access from population centers in the Superior Valley to the north of the Coolgardie Mesa and Paradise Valley populations of the Lane Mountain milk-vetch is provided via Copper City Road, an improved road via Fort Irwin Road, and a paved highway. Using these access routes, the Superior Valley is easily reached, as demonstrated by the noticeable presence of recreational visitors in this portion of the subregion. Interstate 15, State Route 58, and Irwin Road provide access to the subregion from the south (BLM et al. 2005, Appendix R, p. 1579).

Figure 8. Existing OHV routes in Coolgardie Mesa and Paradise Valley populations of Lane Mountain milk‐vetch in 2005. Data were collected for BLM’s West Mojave Plan.

Figure 9. Existing OHV routes in Coolgardie Mesa and Paradise Valley populations of Lane Mountain milk‐vetch in 2012. Data are from BLM’s digital photographs.

OHV use has also increased in the Paradise Valley area between 1998 and 2006 (C. Rutherford, pers. obs. 2006); most of this land was transferred to the Army and public use is prohibited. However, Hessing and Shaughnessy (2011, p. 31) noted that habitat for the LMMV receives negligible protection from OHV use.

Effects of OHV Recreational Use to the Lane Mountain Milk-vetch and Its Habitat

The creation and use of unpaved roads in Lane Mountain milk-vetch habitat can affect the LMMV and its habitat in several ways. These direct and indirect impacts are similar to those described under Effects of Military Training and Operations Activities to the Lane Mountain Milk-vetch and Its Habitat, and include: loss of Lane Mountain milk-vetch plants and nurse shrubs; burying Lane Mountain milk-vetch seeds; destruction of soil structure and disruption of soil function (including soil crusts); altering surface hydrology; increase in wind erosion of soils and dust deposition; disruption of pollination systems; and spread and increase of nonnative plant species/competition. These impacts contribute to changes in vegetation type; increases in fire frequency, size, and intensity; fragmentation and reduction/loss of connectivity; reduced gene exchange; and reduced population persistence (see Military Training and Operations Activities - Effects of Military Training and Operations Activities to the Lane Mountain Milk-vetch and Its Habitat).

Currently the area of impact is smaller than that identified for military activities but the severity is similar. Off-road vehicles cause significant soil compaction with as few as 1 to 10 passes (Webb 2002, p. 292). With ongoing reports of increases in OHV activity and creation of new roads, this increased use would continue to expand the area of impact to Lane Mountain milk-vetch plants and habitat in the Coolgardie Mesa and West Paradise Conservation Areas.

Because of limited staffing and funding, the BLM has reduced abilities to educate the public about the Lane Mountain milk-vetch, its habitat requirements, and appropriate activities on its lands and to enforce laws, regulations, and land management plans (see Regulatory Mechanisms). Although the BLM has installed about 5 mi (8 km) of post and cable fencing to deter unauthorized OHV access in Lane Mountain milk-vetch habitat (Quillman 2013, in litt. April 30), it reported that OHV users have shifted their unauthorized use to adjacent areas and have created new staging areas in the Coolgardie Mesa Conservation Area (Quillman 2013 in litt. April 26). Thus, the barren fenced staging areas remain and new staging areas are being created resulting in the additional loss of Lane Mountain milk-vetch plants and habitat.

In addition, the BLM has limited funds to implement restoration efforts at the locations of these unauthorized OHV activities. Because of the duration of the impacts and time for full recovery taking about 100 to 200 years for desert soils and vegetation (Webb 2002, p. 303), it is likely that natural restoration of Lane Mountain milk-vetch habitat would take about 100 years.

The BLM reports that although it has not documented the direct impacts from vehicles to Lane Mountain milk-vetch plants and their habitat, indirect impacts from travel off open roads could be significant (BLM 2003 Route designation, p. 16). The BLM also stated in their management plan for the area that “the potential operations planned on the Fort Irwin expansion may result in the loss of substantial numbers of [Lane Mountain milk-vetch] plants and areas of habitat, so that the remaining habitat on BLM lands at the Coolgardie Mesa population and the west sliver of the Paradise Valley population must be managed on a reserve-level basis” (BLM et al. 2005, Chapter 4, p. 73).

Conservation Measures Implemented

The BLM identified conservation measures for the Lane Mountain milk-vetch in the West Mojave Plan to reduce the impacts from OHV recreational use to the Lane Mountain milk-vetch and its habitat. These included minimizing vehicle routes of travel and fencing, if deemed necessary, to protect the Lane Mountain milk-vetch (BLM et al. 2005, Chapter 2, p. 16). Although the BLM may want to close many existing routes on BLM lands in the Coolgardie Mesa and West Paradise Conservation Areas, they are constrained by the necessity to provide access to the patchwork of non-BLM lands in the Coolgardie Mesa and Western Paradise Conservation Areas (BLM et al. 2005, Chapter 4, p. 74). When the BLM receives the lands purchased by the Army in the Coolgardie Mesa and West Paradise Conservation Areas, this requirement would be reduced. The date of this transfer of lands, the last of which were purchased by the Army in 2008, is unknown.

The BLM is currently responding to a court order to revisit their route designation decision in the area that includes the Coolgardie Mesa and West Paradise Conservation Areas, and to provide a draft revised route network designation to the public in 2014. This revised designation may or may not include fewer open routes in the two Conservation Areas for the Lane Mountain milk-vetch than currently designated. While the BLM strives to consolidate its designations of open routes to popular destinations in these Conservation Areas to the extent

possible, the road closures may not achieve the level of habitat conservation necessary to avoid direct and indirect impacts to the Lane Mountain milk-vetch (BLM et al. 2005, chapter 4, p. 74).

The BLM is also obligated to provide access to mining claims and mines. In the West Mojave Plan, the BLM proposed a mineral withdrawal for the two Conservation Areas for the Lane Mountain milk-vetch. If Congress approves a mineral withdrawal, the BLM may choose to revisit their route designations in the two conservation areas for the Lane Mountain milk-vetch and close routes to these closed claims within Lane Mountain milk-vetch habitat. However, the mineral withdrawal process, initiated in 2012, is likely to take several years (see Mining Activities, Conservation Measures Implemented and Summary of Analysis of Existing Regulatory Mechanisms).

In 2006, the Service provided funds to the BLM to purchase and install 2 mi (3.2 km) of fencing in the Coolgardie Mesa Conservation Area to secure sites from additional damage from unauthorized OHV recreational use and to initiate restoration activities. In addition, the BLM has installed about 5 mi (8 km) of post and cable fencing in the Coolgardie Mesa Conservation Area. The BLM reports that this method is successful at keeping unauthorized OHV use out of areas that have been fenced. However, as unauthorized use increases or is closed in other areas, OHV users move to new areas and create new staging areas and routes to replace the fenced staging areas and closed area. Therefore, there is a need to do more fencing in Lane Mountain milk-vetch habitat (Quillman 2013 in litt. April 26), and fencing should be implemented prior to the damage caused by OHV activities as the recovery time for soils and vegetation may be a century or more.

In the West Mojave Plan, the BLM stated that they will not issue a permit or authorization for a discretionary action on BLM land that would result in the take of the Lane Mountain milk-vetch (BLM et al. 2005, Chapter 2, p. 28). Most OHV activities including recreational or casual use mining are not discretionary actions and are not subject to permits or authorizations; however, OHV activities associated with mining claims on BLM lands are. Although the BLM would not authorize the direct loss of a Lane Mountain milk-vetch plant for new or expanded discretionary activities, it is unclear if the BLM would authorize an activity that would cause the degradation or loss of Lane Mountain milk-vetch habitat. Recent population reductions may yield negative survey results for the Lane Mountain milk-vetch where the species was recently documented as occurring. Activities in these surveyed areas would not directly result in the loss of Lane Mountain milk-vetch plants but would result in loss of habitat and remove chances for future re-establishment of the milk-vetch nurse shrubs and plants (see Abundance and Population Trends).

As part of the proposed action for the use of additional training lands at Fort Irwin, the Army offered to provide funds or labor to close and rehabilitate roads in the Coolgardie Mesa and West Paradise Conservation Areas on BLM lands. Closure and rehabilitation of unauthorized routes would be an important element in the conservation of the Lane Mountain milk-vetch and would aid in implementation of BLM’s Route Designation Project (BLM 2003 Route Designation, p. 16). Designation and clear marking of open routes in this area, combined with acquisition of private parcels, and closure and obliteration of closed routes would allow law enforcement personnel from the BLM to protect Lane Mountain milk-vetch habitat more

effectively. The physical closure of roads, which the Army proposed to fund, would also increase the level of protection for the Lane Mountain milk-vetch by reducing vehicle access points to its habitat and better enabling the BLM’s rangers to enforce the route network (Service 2006, p. 166 – BO). However, the BLM provided no information that these measures have been implemented or that they would include monitoring.

Another conservation measure is education and enforcement. The BLM has installed an informational kiosk at the Coolgardie Mesa Conservation Area that informs the public that motorized use is permitted only on routes signed “open” (Quillman 2013 in litt., attachment 1, p. 6, dated April 26, 2013). The BLM has seven rangers that patrol 3.2 million ac (1.3 million ha) of BLM land in the California Desert Conservation Area, which includes the Coolgardie Mesa and West Paradise Conservation Areas (Service 2013g, attachment). Their job is to educate the public and enforce applicable Federal laws and, regulations (J. Hohman (Service) email dated April 23, 2013).

Summary of Conservation Measures Implemented

In the West Mojave Plan, the BLM identified minimizing vehicle routes of travel, fencing, education, and enforcement as conservation measures to help the Lane Mountain milk- vetch and its habitat. The BLM has implemented other measures such as public education and enforcement of its route designation decision. Most of these conservation measures have been minimally implemented because of staff and funding shortages.

Energy Development and Transmission Lines:

At the time of listing, we did not identify energy development as a threat to the Lane Mountain milk-vetch. In the 5-year review, we identified energy development including utility- scale wind energy development, as a potential threat to the Lane Mountain milk-vetch. One wind energy company had expressed interest in utility-scale development in the Coolgardie Mesa area (Service 2008, pp. 10–11). However, the BLM denied a permit to this company to place meteorological towers to gather data on wind speeds and frequency.

Renewable Energy Projects

Currently there does not appear to be any energy development projects proposed within the four populations of the Lane Mountain milk-vetch. For those populations on BLM lands, the BLM has designated two conservation areas for the Lane Mountain milk-vetch that they have designated as ACECs (BLM et al. 2005, Chapter 2, p. 108). In 2011, the BLM published its Final Programmatic Environmental Impact Statement on Wind Energy Development on BLM- Administered Lands in the Western United States. In 2012, the BLM and DOE published their Final Programmatic Environmental Impact Statement for Solar Energy Development in Six Southwestern States (Arizona, California, Colorado, Nevada, New Mexico, and Utah. In the preferred alternatives of these documents, the BLM committed to excluding special management areas including ACECs from future wind and solar energy development on BLM lands. When the BLM adopts the preferred alternatives as a CDCA amendment, the BLM would no longer approve wind or solar energy development projects on BLM lands if the proposed project were

77 located in an ACEC (see Summary of Analysis of Existing Regulatory Mechanisms) unless the CDCA is amended again. In addition, the four populations of the Lane Mountain milk-vetch occur within military supersonic corridors (Hagenauer 2006, p. 7). The Department of Defense has found these wind turbines to be incompatible with their military missions in these flight corridors. Thus, given these current management commitments and conflicts with existing uses, at present no wind or solar energy projects are planned to be built or operated in the Coolgardie Mesa or West Paradise Conservation Areas of the Lane Mountain milk-vetch.

The BLM is one of several Federal, State, and local agencies participating in the development of the Desert Renewable Energy Conservation Plan (DRECP). This plan, which is a Natural Communities Conservation Plan (see Summary of Analysis of Existing Regulatory Mechanisms), has a goal of streamlining the permitting processes for several Federal and State environmental regulations for utility‐scale renewable energy development in the California desert; does not include military lands. The DRECP provides coverage to private, local, State, and BLM land ownership within the Plan boundaries (Mojave Desert in California south to the International boundary with Mexico). The Plan aims to meet this goal by streamlining project approvals that are located within development focus areas (DFAs). The DFAs, to the extent practicable, are areas that provide high‐quality renewable energy resource potential, access to existing or planned transmission and other supporting infrastructure, and where impacts to wildlife and natural communities can be appropriately managed and mitigated. The DRECP does not prohibit development on private or some public land outside the DFAs; however, permit efficiencies under the DRECP would not be available for these projects (DRECP 2013, p. 1 Letter to Stakeholders dated March 28; website accessed 6-26-2013; http://www.drecp.org/documents/docs/DFA_and_streamlining_concepts_papers_March_28_201 3.pdf).

The draft DRECP should be released to the public for comment in December 2013. However, various milestone documents (e.g., DFAs, Biological Goals and Objectives, Conservation Management Actions, etc.) have been developed and released that will be used to prepare the draft DRECP. These documents are subject to modification before the draft DRECP is released.

Transmission Lines

Existing and planned transmission corridors were identified in a Programmatic Environmental Impact Statement for the Designation of Energy Corridors in 11 Western States finalized (DOE et al. 2008). The EIS was developed in response to the requirement in section 368 of the Energy Policy Act of 2005 that requires the designation of energy corridors on Federal lands in 11 western states, including California. Transmission corridors may be multi-modal (designated for pipeline and transmission line use), electric only, or pipeline only (DOE et al. 2013, p. S-17). Corridor width is 3,500 ft (1,067 m) unless specified otherwise (DOE et al. 2008, p. S-17) with an identified centerline (DOE et al. 2008, p. S-23). Following the designation of these corridors, the BLM would amend their West Mojave Plan to incorporate the designated corridors (DOE et al. 2008, p. S-23).

Under the DRECP, the transmission corridor width could be increased. This option is being considered and was recently strengthened by the June 3, 2013, the Presidential memorandum to the heads of Federal executive departments and agencies. In this memorandum, the President directed them to establish energy corridors by revising existing transmission corridors and developing new ones. This process began on July 12, 2013 with a plan for producing the Western corridor study and regional corridor assessments.

Locations with respect to the Lane Mountain milk-vetch

There are no documented occurrences of the Lane Mountain milk-vetch within any DFA identified in the current DRECP alternatives. This means there are no sites identified for streamlined renewable energy development (e.g., wind, solar, or geothermal) within the known occurrences or modeled habitat of the Lane Mountain milk-vetch.

The closest existing transmission line is about 0.5 mi (0.8 km) southeast of the Coolgardie Mesa Conservation Area and 6 mi (10 km) south of the West Paradise Conservation Area. The next closest transmission line is more than 8 mi (12.8 km) east of these Conservation Areas and runs north-south to the Fort Irwin cantonment area. There are several transmission lines about 5 mi (8 km) south of the Coolgardie Mesa Conservation Area. A BLM-designated transmission corridor with existing transmission lines is located more than 12 mi (19 km) southeast of the Coolgardie Mesa Conservation Area (California Energy Commission 2012, p. 1 MAP). This corridor appears to be about 1 mi (1.6 km) wide. The section 368 corridor is located more than 14 mi (23 km) southeast of the Coolgardie Mesa Conservation Area. Both corridors are aligned in a northeast to southwest direction. If we assume these corridors would be widened (currently under consideration) and if we assume this would occur and would be up to 6 mi (10 km), the BLM corridor with a current centerline would be about 9 mi (14 km) and the section 368 corridor would be more than 10 mi (16 km) from the Coolgardie Mesa Conservation Area and farther from the West Paradise Conservation Area.

Effects to the Lane Mountain milk-vetch and its Habitat

Currently there are no DFAs, existing transmission lines, or transmission line corridors identified in or close to the locations of the Lane Mountain milk-vetch plants or the Coolgardie Mesa or West Paradise Conservation Areas. Using this information, the DRECP would not likely result in focusing or encouraging renewable energy development, including additional transmission lines or pipelines, in the Coolgardie Mesa or West Paradise Conservation Areas.

1 The California Energy Commission modeled suitable habitat for the Lane Mountain milk-vetch and identified areas in addition to the Goldstone, Brinkman Wash-Montana Mine, Paradise Valley, and Coolgardie Mesa populations. 79 surveys, siting structures to avoid direct impacts, using existing roads and previously disturbed sites, worker education programs, developing and implementing approved restoration plans, weed management plans, and monitoring and adaptive management plans; and compensation for lost habitat (Fraser 2013 pers. comm.). Although currently proposed, these Conservation Management Actions may be modified, added to, or deleted before the Plan is finalized.

The Army has and continues to consider renewable energy projects within the Fort Irwin boundary. Currently, there is no reasonably foreseeable renewable energy project anticipated to occur within any conservation area for the Lane Mountain milk-vetch (Everly 2012 in litt., p. 1). Rather, the Army’s current focus is to install a solar energy project at Fort Irwin’s Main Gate site, which is located east of the known Lane Mountain milk-vetch populations. Any future direction to proceed with renewable energy development at other sites at Fort Irwin has not been made at this time, but the Army continues to evaluate the potential to develop renewable energy projects at other sites at Fort Irwin. As part of this process, the Army would avoid direct adverse effects to known populations of the Lane Mountain milk-vetch at Fort Irwin and the NTC (Everly 2012, in litt., p. 1).

Regarding private lands, we have reviewed recent aerial photography of the Coolgardie Mesa and Paradise Valley Lane Mountain milk-vetch population areas and have observed no evidence of construction of renewable energy projects. San Bernardino County provided a list of proposed small solar energy projects in western San Bernardino County. No project is located near the Coolgardie Mesa or Paradise Valley populations of the Lane Mountain milk-vetch. Recalling that the Army recently purchased most private lands within the Coolgardie Mesa and West Paradise Conservation Areas as mitigation for the Fort Irwin Expansion, these lands are no longer available for future development including renewable energy. Additional private lands occur near to but outside the Coolgardie Mesa and West Paradise Conservation Area boundaries. While these lands could be developed for renewable energy in the future, there would be no direct impacts to the Lane Mountain milk-vetch because of their location.

Summary of Effects of Renewable Energy Projects and Transmission Lines

Renewable energy development within the range of the Lane Mountain milk-vetch is unlikely to occur based on current information. Recent BLM processes and decisions have discouraged renewable energy development in the known distribution of the Lane Mountain milk-vetch. Wind energy development is unlikely to occur because designated military flight corridors are located above the known distribution of the Lane Mountain milk-vetch and wind turbine operations interfere with radar use. Although in development, the DRECP has currently identified DFAs outside the known distribution of the Lane Mountain milk-vetch. If there are no DFAs in the final DRECP, this means that it would be more difficult to obtain permits to locate renewable energy projects in the known range of the Lane Mountain milk-vetch. Preparing the environmental compliance documents for these projects would take a few years and their completion would be a lower priority for the BLM. We are unable to speculate what the decision will be regarding revising existing transmission corridors and developing new ones as directed by the President’s June 2013 memorandum. However, we do know that existing transmission corridors and lines are located outside the known range of the milk-vetch and if the corridors are widened substantially, they would continue to be outside the known distribution of the species.

Based on this available information, we conclude that existing or proposed renewable energy development or new transmission corridors/lines is not likely to be constructed or operated within the range of the Lane Mountain milk-vetch.

Anthropogenic Dust

In the final rule to list Lane Mountain milk-vetch, we did not identify dust as a threat to the species (Service 1998). However, we discussed that military activities and OHV recreation (which are anthropogenic dust-generating activities) as threats in the context of destruction of habitat and individual Lane Mountain milk-vetch plants. In our 5-year review (Service 2008), we again did not identify dust specifically as a threat in the Five-factor Analysis, but we discussed that dust had been identified as a potential threat. We reported that, in anticipation of indirect impacts of military training and operations to the Lane Mountain milk-vetch, we had a study conducted on the effects of anthropogenic dust on several metrics of the plant’s growth. The results of this and other studies and their implications about the future of the Lane Mountain milk-vetch and its habitat are discussed below.

Description of Anthropogenic Dust

Fugitive dust is significant atmospheric dust or particulate matter that becomes airborne from mechanical disturbance from open sources and not a confined flow stream (EPA 2012 website) or point source such as a smoke stack. It is also called anthropogenic dust because it is caused by human activities, fugitive dust is included in the larger category of particulate matter.

Fugitive or anthropogenic dust (dust) is moved into the atmosphere in two ways, by suspension and saltation (USDA Natural Resource Conservation Service (NRCS) 2007, p. 2). Suspension occurs when the wind lifts very fine soil and dust particles into the air. Once in the atmosphere, these particles can be carried very high and transported over extremely long distances. Saltation occurs when the wind lifts fine soil particles into the air and they drift horizontally across the surface increasing in velocity as they go. When soil particles strike the surface again, they either rebound back into the air or knock other particles into the air (USDA NRCS 2007, p. 2). While soil can be blown away at virtually any height above the ground, the majority (more than 93 percent) of soil movement takes place at or below 3 ft (0.9 m) (USDA NRCS 2007, p. 2).

Soil crusts, also referred to as cryptobiotic soil crusts, are organic crusts that form on soil surfaces in southwestern deserts including the Mojave Desert. They are assemblages of algae, cyanobacteria, bacteria, lichens, and mosses and various metabolic by-products cemented into a semi-permeable soil surface. These soil crusts perform a variety of functions including enhancing soil surface stabilization (Fletcher and Martin 1948; Loope and Gifford 1972; Blackburn 1975; Rogers 1977; Brotherson and Rushforth 1983; Graetz and Tongway 1986; as cited in DeFalco 1995, p. xiii). They are also strong indicators of multiple ecosystem functions, including nitrogen fixation (Evans and Ehleringer 1993, p. 316), carbon fixation (Beymer and Klopatek 1991, as cited in Bowker et al. 2008, p. 1534), soil building and retention (Reynolds et al. 2001, p. 7126), and modification of hydrological processes (Alexander and Calvo 1990; as cited in Bowker et al. 2008, p. 1534). In desert regions, they respond predictably to surface

degradation (e.g., strong negative impacts), and can signify impending changes in ecosystem state (Belnap 1995, pp. 53–54). Thus, soil crusts indicate ecosystem function that is relatively easily lost (Bowker et al. 2008, p. 1534).

The quantity of dust that is generated is closely linked to the management of soils and the

amount or area of mechanical disturbance or fire. Soil disturbances alter soil structure by breaking-up soil aggregates (including soil crusts) and allowing small particles to be easily suspended in the air by wind (USDA NRCS 2007, p. 3); therefore, the greater the area of soil experiencing mechanical disturbance or fire, the greater the amount of dust. Restoration of soil crusts, which stabilize soils and reduce fugitive dust, requires decades (Bowker et al. 2008, p. 1534) if the soil crusts were degraded and the site is left undisturbed. Restoration of soil crusts in an area impacted by fire may take longer as fire destroys soil crusts.

Location of Anthropogenic Dust with Respect to the Lane Mountain Milk-vetch Populations and Its Habitat

Common sources of dust in the western Mojave Desert are human activities involving mechanical disturbance of arid soil or fire. Mechanical disturbance of the soil is caused by activities such as vehicle traffic (military training and operations activities and OHV use), trampling by livestock and people, and land clearing (such as mining and energy development). Such uses are increasing exponentially in arid and semi-arid areas of the world (Belnap et al. 2001, p. 49). These activities produce dust by degrading soil crusts and exposing the soils to wind movement by suspension and saltation, and denuding the land of vegetation and exposing areas from which dust can be raised (Adams et al. 1982; Grantz et al. 1998; Padgett et al. 2007, 275–285; Wijayratne et al. 2009, p. 82). Unlike mechanical disturbance, fire destroys biological soil crusts.

As mentioned above, military training and operations activities occur adjacent to or are planned to occur in or adjacent to the Goldstone, Brinkman Wash-Montana Mine, and Paradise Valley populations. Dirt roads and OHV activities occur throughout the Coolgardie Mesa population as do mining activities. Livestock grazing no longer occurs and no known energy development occurs or is currently planned to occur in the known range of the Lane Mountain milk-vetch.

Effects of Anthropogenic Dust to the Lane Mountain Milk-vetch and Its Habitat

Soil and plant characteristics of low- and mid-elevation desert ecosystems in the U.S., which includes the western Mojave Desert, indicate that these ecosystems evolved with low levels of soil surface disturbance (Belnap et al. 2001, p. 41). Because of their evolutionary history, these arid regions appear to be more negatively affected by soil surface disturbances than regions such as the Great Plains that evolved with higher levels of surface disturbance (Belnap et al. 2001, p, 42) (e.g., herds of large grazing animals and fire). Because soil crusts play an important role in soil stabilization and other soil processes and are highly susceptible to degradation or loss from the frequent and large-scale disturbance activities recently introduced by man in the western Mojave Desert (e.g., livestock grazing, military training and operations

activities, mining, OHV use, fire, etc.), dust at its current levels is likely a recent phenomenon to the Mojave Desert.

Effects to Nurse Shrubs: Dust can disrupt physical and physiological processes in desert shrubs. Beatley (1965, p, 1621; as cited in Sharifi et al. 1997, p. 837) found that dust deposition in the Mojave Desert of Nevada caused plant defoliation and shoot death in creosote bush (Larrea tridentata). Dust can interfere with plant growth by clogging pores and reducing light interception (Ferguson et al. 1999, p. 2). Other effects reported include a reduction in photosynthesis and increase in leaf temperature (Eller 1977, p. 106; Thompson et al. 1984, p. 177; Farmer 1993, p. 63). Sharifi et al. (1997, p. 837) studied the physiological responses of Mojave Desert shrubs exposed to dust. They discovered that dusty shrubs close to military activities at the NTC exhibited a 21 to 58 percent reduction in photosynthesis in the summer and a decrease in total shoot length. They also learned that the dusty plants had reduced maximum leaf conductance, transpiration, and instantaneous water use efficiency.

Dust on desert plants raises the temperatures of the plants. Sharifi et al. (2009, pp. 843– 844) determined that the temperatures of dusted leaves and photosynthetic stems were 3.6–5.4 ºF (2.0–3.0 ºC) higher than those of undusted plants, due to greater absorption of infra-red radiation. At high ambient summer temperatures of 104–113 ºF (40–45 ºC) in the western Mojave Desert, leaf temperatures of perennial shrubs approaching or exceeding 113 ºF (45 ºC) have the potential to cause significant heat stress and permanent tissue damage (Sharifi et al. 1997, p. 844). Heavy dust on a leaf could also cover a significant percentage of the stomatal pores, thereby lowering leaf conductance and causing elevated leaf temperatures.

Dust also affects photosynthesis. Dust significantly increased photosynthetically active radiation reflectance. More reflection and less absorption of light means reduced photosynthesis by the dusted plant. Dusted shrubs produced smaller leaf areas and greater leaf-specific masses, suggesting that the short-term effects of reduced photosynthesis and decreased water-use efficiency may cause lowered primary production in desert plants exposed to dust during seasons when photosynthesis is occurring. Regarding other physiological processes, a thick coating of dust on a leaf surface theoretically would produce a decrease in boundary layer conductance across the leaf/air transition that would lower the plant’s transpiration rate. This reduced rate would lead to lower evaporative cooling, increased leaf temperatures, and reduced growth (Darley 1966, pp. 147–150; Borka 1980, p. 75; Sharifi et al. 1997, p. 844).

Most species of nurse shrubs used by the Lane Mountain milk-vetch are 3 ft (0.9 m) tall or shorter and most soil movement via dust takes place at or below this height (USDA NRCS 2007, p. 2). After considering the physical and physiological effects to desert shrubs from dust as reported by Sharifi et al. (1997, 2009), we conclude that dust may have similar effects to the physical and physiological processes of most or all nurse shrub species used by the Lane Mountain milk-vetch.

Effects to the Lane Mountain milk-vetch: To study the effects of dust to established Lane Mountain milk-vetch plants, Wijayratne et al. (2009, p. 82) conducted a study in the spring of 2004, on Lane Mountain milk-vetch plants in the Coolgardie Mesa population. The study did not examine the effects of dust on Lane Mountain milk-vetch seedlings. During this study,

Wijayratne et al. (2009, pp. 86–87) learned that dust deposition for the Coolgardie Mesa population was on the upper end of yearly dust accumulation rates reported for the Mojave Desert by Reheis (2006, p. 494) during a 16-year period. This dust deposition rate may or may not increase when the Army initiates brigade-level training in the Western Expansion Area.

Wijayratne et al. (2009, p. 84) found that as dust concentration increased, shoot growth for the Lane Mountain milk-vetch decreased, and there was a trend towards lower leaf production. Net photosynthesis increased as the concentration of dust on leaves increased, but no difference in water stress across the dust concentration gradient was detected. They found a positive correlation between dust level and leaf temperature and between leaf temperature and leaf-level photosynthesis rate. High dust concentrations were associated with low monthly rainfall, high mean maximum daily temperature, and proximity to a single track dirt road (Wijayratne et al. 2009, p. 84).

Dust-induced increases in leaf temperatures and subsequent photosynthetic rates during early spring would extend the activity period that the Lane Mountain milk-vetch could maintain positive net photosynthetic rates (i.e., warmer temperatures would result in an earlier start to the growing season). However, as spring temperatures increase, leaf temperatures of dusted plants likely lowered net photosynthetic rates, thus reducing shoot growth (Wijayratne et al. 2009, p. 86). We postulate that warmer leaf temperatures in late spring caused by a combination of dust and climate change likely affect Lane Mountain milk-vetch plants by requiring an increased amount of water for growth and successful reproduction. If this increased amount of water is not available, the Lane Mountain milk-vetch may respond by reducing flower and seed production or abandoning reproduction for the year. The study did not examine whether reproductive effort during the life of the plant is compromised by diminished growth (Wijayratne et al. 2009, p. 85) and (or) higher temperatures. Because the species occurs in the Mojave Desert, which is a physiologically stressful environment, additional physiological impacts such as those from anthropogenic dust would further stress the Lane Mountain milk-vetch. Based on the available information, we postulate that the effects of anthropogenic dust to the Lane Mountain milk-vetch are likely to diminish its reproductive effort during the life of the plant. Reduced seed production would likely reduce recruitment of Lane Mountain milk-vetch plants.

Extent of Impact on the Lane Mountain Milk-vetch

Several human activities cause mechanical disturbance to the soil and generate dust to all four Lane Mountain milk-vetch populations. Past, current, and planned activities that are dust sources include military training and operations activities, mining activities, and OHV activities.

Coolgardie Mesa Population: Authorized and unauthorized OVH activities and mining occur within and adjacent to the Coolgardie Mesa population of the Lane Mountain milk-vetch. This population is exposed to dust created more than 100 mi (161 km) of dirt roads crossing this population and the creation and use of unauthorized roads and staging and camping areas (see OHV Use). OHV use is evident throughout the Coolgardie Mesa population (Wijayratne et al. 2009, p. 82 personal observation) and may increase in intensity in the future (Wijayratne et al. 2009, p. 82).

Paradise Valley and Brinkman Wash-Montana Mine Populations: Authorized OHV activities also occurred at the Paradise Valley and Brinkman Wash-Montana Mine populations of the Lane Mountain milk-vetch until recently, when lands comprising most of the Paradise Valley and all of the Brinkman Wash-Montana Mine populations were transferred from the BLM to the Army and their boundaries were fenced or signed to deter public access. Despite the land transfer to the Army in 2002, unauthorized OHV activity continued to be reported in both Lane Mountain milk-vetch populations (Hessing and Shaughnessy 2011, p. 31). The NTC intends to initiate brigade-level military training and operations activities in and adjacent to the Paradise Valley and Brinkman Wash-Montana Mine populations.

Goldstone Population: The Goldstone population of the Lane Mountain milk-vetch has and continues to be off-limits to OHV recreation, mining, and most military training and operations activities. It is adjacent to two current military training and operations areas and the Manix tank trail.

Based on Sharifi et al.’s (1997) work and others, there is concern that the habitat quality within the designated Conservation Areas for the Lane Mountain milk-vetch may be adversely affected by airborne dust raised by vehicles, troops, and equipment in and adjacent to these military training and operations areas ( Service 2004, p. 51; Wijayratne et al. 2009, p. 81). Although most sources of dust would not be from the areas managed by the Army and BLM as Conservation Areas for the Lane Mountain milk-vetch, dust travels and is a potential indirect threat to the milk-vetch in these Conservation Areas. The Lane Mountain milk-vetch populations in the Conservation Areas occur on or adjacent to lands subject to increased mechanical activities generating dust, including increased vehicular traffic in unpaved areas (Wijayratne et al. 2009, p. 81) (e.g., existing and planned military training and operations activities, authorized and unauthorized OHV use, etc.). If leaf surface dust reduces photosynthesis in the Lane Mountain milk-vetch, as it does with other native plants, the long- term effect of decreased growth and reproduction could negatively affect the population viability of this rare species (Wijayratne et al. 2009, p. 82). Long-term exposure of the Lane Mountain milk-vetch to a degraded habitat (including exposure to dust) could counteract the effectiveness of the Conservation Areas and fenced areas as a primary means of protection or conservation for the species.

Summary of Effects from Anthropogenic Dust

Anthropogenic dust generated from past and current human activities (e.g., livestock grazing, military training and operations activities, OHV use, mining, fire, etc.) and proposed military training and operations activities has the potential to reduce the vigor of nurse shrubs and the reproductive potential of the Lane Mountain milk-vetch. Past and current human activities in and adjacent to the distribution of the Lane Mountain milk-vetch should be considered because the restoration of soil crusts, which stabilize soils and reduce fugitive dust, requires decades if the sites are left undisturbed. Given past, current, and planned human activities in and adjacent to the distribution of the Lane Mountain milk-vetch, the continuation and increase of this threat in the foreseeable future is likely throughout the range of the species as these sources of dust occur or are proposed to occur in and adjacent to all Lane Mountain milk-vetch populations. While anthropogenic dust has a likelihood of affecting the habitat (via

reduced nurse shrub vigor), and individuals of the Lane Mountain milk-vetch, there is no way to quantify the severity of this threat at this time.

Predation

At the time of listing, predation was not considered a threat. Domestic sheep grazing previously occurred on BLM lands on Coolgardie Mesa where Lane Mountain milk-vetch occurs, but the lessees have not requested to graze in the two ephemeral allotments in the known distribution of the species since1992 (BLM et al. 2005, Chapter 3, p. 212). In the 5-year status review, we identified vegetative, seed, and root predation as threats or potential threats to the Lane Mountain milk-vetch. Both vegetative and seed predation were observed in the field, the former from small mammals and aphids, and the latter from wasp larvae (Service 2008, p. 7). Root predation was observed under greenhouse conditions from fly larvae (Sharifi, University of California, Los Angeles, pers. comm. 2006; as cited in Service 2008, p. 7). Observations indicate that damage from vegetative predation may be heavy on individual Lane Mountain milk-vetch plants (Service 2008, p. 7).

Description of Predation on the Lane Mountain Milk-vetch

Vegetative predation: Biologists have observed swarms of phloem-sucking aphids on individual Lane Mountain milk-vetch plants (Hopkins 2003; C. Rutherford, pers. obs. 2003; M. Hessing, pers. obs. 2005; cited in Service 2008, p. 7). Hopkins (2005a, p. 2) reported observing one Lane Mountain milk-vetch plant covered with aphids, ants, ladybugs, sawflies, and beetles while two plants nearby were not being eaten by these insects.

Field biologists have observed snipping of Lane Mountain milk-vetch branches by small mammals on various occasions (Hopkins 2003; C. Rutherford, U.S. Fish and Wildlife Service, pers. obs. 2003; M. Hessing, Fort Irwin botanist, pers. obs. 2005; as cited in Service 2008, p. 7). The presence of scat from jackrabbits suggested that they may be responsible for such damage. Hessing and Shaughnessy (2011, p. 39) reported that 38 of 107 Lane Mountain milk-vetch plants occurring in all four populations of the milk-vetch had evidence of being grazed. The evidence ranged from Lane Mountain milk-vetch plants trimmed below the flower and fruit line to plants trimmed to the base. Plants with few fruits were grazed more frequently (63.6 percent) than plants with no fruits (41.6 percent) and plants with many fruits (37.1 percent). Rigid-based Lane Mountain milk-vetch plants had a high occurrence of herbivory (63.6 percent) compared to non- woody (18.9 percent), woody (32 percent), and very woody (33.3 percent) plants. These observations indicate that damage from vegetative predation may be heavy for individual plants, but does not appear to be widespread within the Lane Mountain milk-vetch populations.

Predation on seedlings has been observed and resulted in damage or removal of the apical meristem or by consumption of the whole plant leaving just the stem below the cotyledons. Often, the stem was eaten to the ground and difficult to see (Huggins et al 2011, pp. 62–63). Caging reduced, but did not stop predation (Huggins et al. 2100, p. 63). Darkling beetles (Eleodes sp.), blister beetles (Lytta insperata), and side-blotch lizards (Uta stansburiana) were frequently observed moving in and out of exclusion cages (Huggins et al. 2011, p. 63) All are

herbivores or facultative herbivores (Johnson and Triplehorn 2004; Nagy 1983 as cited in Huggins et al. 2011, p. 63).

Seed predation: Both vertebrate and invertebrate species likely prey on Lane Mountain milk-vetch seeds. Predation of Lane Mountain milk-vetch seeds by bruchid wasps has been observed in the field and in the greenhouse (Service 2008, p. 7). Females lay eggs in the unripe plant ovaries, which are then consumed by the emerging wasp larvae. Although we have no direct evidence pertaining to the Lane Mountain milk-vetch, small mammals and birds in the area likely eat its seeds based on the size of the seed. Various birds, rabbits, and rodents feed upon the seeds and pods of other Astragalus species (Army 2002, p. 8). Many small mammals, including antelope ground squirrels (Ammospermophilus leucurus), Mohave ground squirrels (Xerospermophilus mohavensis), pocket mice (Perognathus sp.), and kangaroo rats (Dipodomys spp.), consume and cache seed from desert plants (Brylski 2008 p. 1; Johnson and Harris 2008, p. 1; Gustafson 1993 as cited in Defenders of Wildlife and Stewart 2005, p. 12).

Root predation: Root predation was observed in greenhouse conditions. Sharifi (UCLA, pers. comm. 2006) reported that 70 Lane Mountain milk-vetch plants died after fly eggs hatched and larvae consumed the root systems. Although this factor may be a concern for future propagation efforts, the drier desert conditions would likely preclude this kind of damage from occurring under natural conditions.

Summary of Effects from Predation

It is likely that predation of Lane Mountain milk-vetch seeds, vegetative tissue, and roots is occurring on an ongoing basis. Given the cyclic nature of insect populations and small mammal populations, it is also likely that the extent to which predation is occurring throughout the range of Lane Mountain milk-vetch varies from year to year. Because Lane Mountain milk- vetch has evolved within this habitat, the species has adapted to some level of predation. There is no evidence from observations of predation on Lane Mountain milk-vetch that individuals have been killed from this activity. It is more likely that predation reduces the vigor, including reproductive output, of the species.

Drought, Precipitation Patterns, and Climate Change

At the time of listing and in the 5-year review, we did not identify drought, precipitation patterns, or climate change as threats to the Lane Mountain milk-vetch. Below we describe the current and potential threats to the Lane Mountain milk-vetch and its habitat from drought and climate change.

Drought in the Range of the Lane Mountain Milk-vetch

“Drought” is defined as a degree of dryness when compared to an average amount of precipitation and the duration of the dry period. Thus, successive years in which the annual amount of precipitation at a location is less than the average annual amount is considered a drought for those years.

Historically drought has been a natural reoccurring event of the Mojave Desert. For the past century or longer, long-term wet and dry periods in the Mojave Desert have alternated more or less regularly at 20- to 30-year intervals. Between 1893 and 2001, significant drought periods occurred within the region (1893–1904; and 1942–1956), with a brief drought period in the late 1980s (Hereford et al. 2004, p. 2). These drought periods are associated with the Pacific Decadal Oscillation that causes multi-decadal-scale variability such as prolonged dry and wet episodes (Hereford et al. 2006, pp. 22–25). The last wet period in the Mojave Desert began in 1976 and ended in 1998 (22 years).

The current drought in the western Mojave Desert began in the fall of 1998 (Hereford et al. 2006, p. 21) and continues. Despite an unusually wet 2005 (16 in (40.7 cm)), this drought period has a mean annual precipitation of 4.5 in (11.4 cm) compared to the relatively wet years preceding it from 1991 to 1998, in which the mean annual precipitation was 6.3 in (16.0 cm) (Huggins et al. 2010, p. 122). These wet years represent the end of a wet period from 1976 to 1998 (Hereford et al. 2006, p. 19) that contributed to the high Lane Mountain milk-vetch population numbers recorded in 1999.

While the difference in precipitation between these wet and dry periods is considerable, (1.8 in (4.6 cm) or a 21 percent difference), the severity of the drought and its impact on the Lane Mountain milk-vetch is better appreciated by considering the precipitation pattern before and after the 2005 rainfall season. The six-year period between 1999 and 2004 had a mean annual precipitation of 4.0 in (10.05 cm), and the four-year period from 2006 to 2009 had a mean annual precipitation of 2.4 in (6.19 cm). The year 2007 had the lowest precipitation since 1991, 0.9 in (2.2 cm). Thus, the mean precipitation may change little during time but if most of the precipitation occurs in one or two scattered years with back-to-back years that are drier than the mean, the result is a prolonged drought caused by an unbalanced precipitation pattern.

Climate Change in the Range of the Lane Mountain Milk-vetch

“Climate” refers to an area's long-term average weather statistics (typically for at least 20- or 30-year periods), including the mean and variation of variables, such as temperature, precipitation, and wind. “Climate change” refers to a change in the mean and/or variability of climate properties that persists for an extended period (typically decades or longer), whether due to natural processes or human activity (Intergovernmental Panel on Climate Change (IPCC) 2007a, p. 78). Although changes in climate occur continuously throughout geological time, changes are now occurring at an accelerated rate.

Scientific measurements spanning several decades demonstrate that changes in climate are occurring, and that the rate of change has increased since the 1950s. Examples include warming of the global climate system, and substantial increases in precipitation in some regions of the world and decreases in other regions (for these and other examples, see IPCC 2007a, p. 30; Solomon et al. 2007, pp. 35–54, 82–85). Results of scientific analyses presented by the IPCC show that most of the observed increase in global average temperature since the mid-20th century cannot be explained by natural variability in climate and is “very likely” (defined by the IPCC as 90 percent or higher probability) due to the observed increase in greenhouse gas (GHG) concentrations in the atmosphere from human activities, particularly carbon dioxide emissions

from use of fossil fuels (IPCC 2007a, pp. 5–6 and figures SPM.3 and SPM.4; Solomon et al. 2007, pp. 21–35). Further confirmation of the role of GHGs comes from analyses by Huber and Knutti (2011, p. 4), who concluded it is extremely likely that approximately 75 percent of global warming since 1950 has been caused by human activities.

All models (not just those involving climate change) have some uncertainty associated with projections due to assumptions used, data available, and features of the models. For climate change models, this includes factors such as assumptions related to emissions scenarios, internal climate variability, and differences among models. Despite this, however, under all global models and emissions scenarios, the overall projected trajectory of surface air temperature is one of increased warming compared to current conditions (Meehl et al. 2007, p. 762; Prinn et al. 2011, p. 527). As more information becomes available, climate models, emissions scenarios, and associated assumptions, data, and analytical techniques will continue to be refined, as will interpretations of projections. For instance, some changes in conditions are occurring more rapidly than initially projected, such as melting of Arctic sea ice (Comiso et al. 2008, p. 1; Polyak et al. 2010, p. 1575). Since 2000 the observed emissions of greenhouse gases, which are a key influence on climate change, have been occurring at the middle to higher levels of the various emissions scenarios developed in the late 1990s and used by the IPPC for making projections (e.g., Raupach et al. 2007, Figure 1, p. 10289; Manning et al. 2010, Figure 1, p. 377; Pielke et al. 2008, entire). In addition, the best scientific and commercial data available indicate that the average global surface air temperature is increasing and several climate-related changes are occurring and will continue for many decades even if emissions are stabilized soon (Meehl et al. 2007, pp. 822–829;; Gillett et al. 2011, entire).

There is broad consensus among climate models that the arid regions of the southwestern United States will become drier in the 21st century and that the transition to a more arid climate is already underway (Archer and Predick 2008, p. 23). The available information indicates that this climate variation is greater than past variations for the southwest. As climate changes, temperature will increase substantially and some areas of the southwestern United States will become more arid than in the past (Overpeck et al. 2012, p. 10).

Recent climate data show that the southwestern United States is already experiencing climate change. The average daily temperatures for the 2001–2010 decade were the highest in the southwestern United States from 1901 through 2010 (Overpeck et al. 2012, p. 2) with temperatures almost 2.0 ºF (1.1 ºC) higher than historic averages, with fewer cold snaps and more heat waves (Hoerling et al. 2012, pp. 74–92). More heat waves occurred in the past decade compared to average occurrences in the 20th century (Overpeck et al. 2012, p. 5). The recent drought has been unusually severe relative to droughts of the last century. The areal extent of drought in the southwestern United States during 2001–2010 was the second largest observed for any decade from 1901 to 2010 (Overpeck 2012, p. 2). The period since 1950 has been hotter than any comparably long period in at least 600 years (Graumlich 1993, pp. 249–255; Salzer and Kipfmueller 2005, pp. 465–487; Millar et al. 2006, pp. 273–287; Ababneh 2008, pp. 59–78; Bonfils et al. 2008, pp. 6404–6424; Stevens et al. 2008, pp. 1–15; Salzer et al. 2009, pp. 20348– 20353; Woodhouse et al. 2010, pp. 21283–21288; Hoerling et al. 2012, pp. 74–92). Compared to temperature, precipitation trends vary considerably across the region, with portions experiencing both decreases and increases (Hoerling et al. 2012, pp. 74–92). There is mounting

evidence that the combination of human-caused temperature increases and recent drought has influenced widespread tree mortality (Van Mantgem et al. 2009, pp. 521–524; Allen et al. 2010, pp. 660–684 and, increased fire occurrence and area burned (Westerling et al. 2006, pp. 940– 943).

Climate change models for the southwestern United States predict with a high degree of confidence the following climate changes during the 21st century. Seasonal temperatures in all seasons will increase (Overpeck et al. 2012, p. 5). Surface temperatures in the Southwest will continue to increase substantially, with more warming in summer and fall than winter and spring. Summer heat waves will become longer, hotter, and more frequent (Overpeck et al. 2012, p. 5). Winter cold snaps will become less frequent but not necessarily less severe (Overpeck et al. 2012, p. 4). Droughts in parts of the southwestern United States will become hotter, more severe, and more frequent (Overpeck et al. 2012, p. 7). Droughts will be exacerbated by warmer summer temperatures in the future (Overpeck et al. 2012, p. 6). Precipitation will increase slightly in the eastern Chihuahuan Desert and decrease westward through the Sonoran and Mojave Deserts. While precipitation events will likely decrease in frequency, they will increase in severity producing a greater likelihood of drought for the southwestern United States and an increased risk of flooding and associated erosion (Karl et al. 2009, pp. 132–133; These projections are consistent with trends observed in recent climate history. High-intensity storms will likely become more common (Archer and Predick 2008, p. 24), while winter precipitation will decrease by 9 to 29 percent by the end of the 21st century (Overpeck et al. 2012, p. 6). Climate change will also lead to increased concentrations of airborne particulates and pollutants from wildfires (see Increase in Fire Frequency, Size, and Intensity) and dust storms (see Anthropogenic Dust above) (Overpeck et al. 2012, p. 10).

Effects of Drought and Climate Change on Species and Their Habitats

Various changes in climate may have direct or indirect effects on species. These effects may be positive, neutral, or negative, and they may change over time, depending on the species and other relevant considerations, such as threats in combination and interactions of climate with other variables (for example, habitat fragmentation) (IPCC 2007a, pp. 8–14, 18–19). Identifying likely effects often involves aspects of climate change vulnerability analysis. Vulnerability refers to the degree to which a species (or system) is susceptible to, and unable to cope with, adverse effects of climate change, including climate variability and extremes. Vulnerability is a function of the type, magnitude, and rate of climate change and variation to which a species is exposed, its sensitivity, and its adaptive capacity (IPCC 2007a, p. 89; see also Glick et al. 2011, pp. 19–22). There is no single method for conducting such analyses that applies to all situations (Glick et al. 2011, p. 3). We use our expert judgment and appropriate analytical approaches to weigh relevant information, including uncertainty, in our consideration of the best scientific information available regarding various aspects of climate change.

Changes in climate can have a variety of direct and indirect impacts on species, and can exacerbate the effects of other threats. Rather than assessing “climate change” as a single threat in and of itself, we examine the potential consequences to species and their habitats that arise from changes in environmental conditions associated with various aspects of climate change. For example, climate-related changes to habitats, plant-pollinator relationships, disease and

disease vectors, or conditions that exceed the physiological tolerances of a species, occurring individually or in combination, may adversely affect the status of a species. Vulnerability to climate change impacts is a function of sensitivity to those changes, exposure to those changes, and adaptive capacity (IPCC 2007, p. 89; Glick et al. 2011, pp. 19–22). In evaluating the status of a species, we use the best scientific and commercial data available, and this includes consideration of direct and indirect effects of climate change.

There is still a degree of uncertainty associated with projecting precise changes in future climate properties, due in part to uncertainties about future emissions of greenhouse gases (Stainforth et al. 2005, pp. 403–406; Duffy et al. 2006, pp. 873–874), and to the inability to predict change at a local scale. Using currently available models, it is difficult to state exactly how a species with a small range, such as the Lane Mountain milk-vetch, will respond to climate change. Responses may include changes in distribution, population size, and physiological and physical characteristics (Parmesan and Mathews 2005, p. 373). Several published studies predict how some biotic communities may respond to changes in temperature and precipitation trends (Parmesan and Mathews 2005, pp. 333–374; IPCC 2007a, pp. 1–21; IPCC 2007b, pp. 1–22; Jetz et al. 2007, pp. 1211–1216; Kelly and Goulden 2008, pp. 11823–11826; Loarie et al. 2008, pp. 1–10; Miller et al. 2008, pp. 1–17). For example, in the interior western region of the United States, some species may respond to increases in temperature by shifting their range to cooler areas that are higher in altitude or latitude. Others may be unable to shift their range resulting in local extirpations and a decreased range.

Effects of Drought and Climate Change on Species and Habitats in the Southwestern Deserts

We know that changes in temperature and precipitation interact to directly impact vegetation and ecosystem processes in the desert southwest (Archer and Predick 2008, p. 24). Plants and animals in the desert live near their physiological limits. Slight changes in temperature and precipitation will substantially alter the composition, distribution, and abundance of species, and the impacts of land use (Archer and Predick 2008, p. 24).

Climate change has affected the distribution of plant and animal species in the desert southwest, and in the future, it will exert a greater effect. Researchers have reported that observed changes in climate are associated strongly with some observed changes in geographic distributions of species in the Southwest. Ecosystem function and the functional roles of resident species will be affected. Observed changes in climate are associated strongly with some observed changes in the timing of seasonal events in the life cycles of species in the region (e.g., initiation and duration of reproductive season). Changes in vegetative land cover will be substantial with vegetation composition, diversity, and growth likely altered (Archer and Predick 2008, p. 25). The death of plants in some areas of the Southwest also is associated with increases in temperature and decreases in precipitation (Overpeck et al. 2012, p. 8).

Projected increases in the frequency and intensity of drought will cause major changes in vegetation cover. During drought, living shrubs may shed foliage in response to water stress, and to reduce carbon allocation and increase water-use efficiency (Hereford et al. 2006, pp. 13– 34; Huggins et al. 2010a, p. 121). This process creates defoliated gaps in shrub canopies, reducing their capacity to shade sub-canopy microhabitats. Higher temperatures and decreased

soil moisture will likely reduce the stability of soil aggregates. Loss of vegetative cover and reduced soil aggregate stability, coupled with increases in precipitation intensity, will dramatically increase potential erosion rates. Wind erosion will have continental-scale impacts on downwind ecosystems (Archer and Predick 2008, p. 24) and increase the frequency and intensity of dust deposition on plants (see Anthropogenic Dust) New or increased disturbances will occur from increases in wildfire (see Increases in Fire Frequency, Size, and Intensity) and the outbreak of pests and disease (Archer and Predick 2008, p. 25).

Habitat is dynamic, and some species may move from one area to another over time. Climate change will be a particular challenge for biodiversity because the interaction of additional stressors associated with climate change and current stressors may push species beyond their ability to survive (Lovejoy 2005, pp. 325–326). The synergistic implications of climate change and habitat fragmentation are the most threatening facet of climate change for biodiversity (Hannah et al. 2005, p. 4).

Effects of Drought and Climate Change to the Lane Mountain Milk-vetch and Its Habitat

Effects to Lane Mountain milk-vetch: Recent data indicate the decline in the population size of Lane Mountain milk-vetch occurred with the ongoing (1999–present) severe drought in the Mojave Desert (Huggins et al. 2010a, p. 120). Huggins et al. (2010a, p. 120) reported about an 88 percent reduction in population size as measured by aboveground individuals on Lane Mountain milk-vetch permanent study plots monitored since 1999. This loss of plants, when applied to the entire range of the species, would mean the number of Lane Mountain milk-vetch plants had declined from an estimated 5,723 plants in 1999 (Army 2002, p. 1) to 686 in 2009 (Huggins et al. 2010a, p. 123). This recent population estimate is less than the number of Lane Mountain milk-vetch plants known when listed as endangered in 1998. Huggins et al. (2010a, p. 120) noted that drought conditions, which began in 1999, are predicted to continue for decades (Hereford et al. 2006, pp. 22 and 25), or may continue indefinitely under warmer temperature conditions projected by global climate change type drought (Breshears et al. 2005, p. 15148; Cook et al. 2004, p. 1018). Between 1999 and 2009, nine of these years had precipitation amounts less than the mean for 1991–1998 (Huggins et al. 2010a, p. 122).

Precipitation amounts, timing, and frequency may be key factors in seedling growth and survival of Lane Mountain milk-vetch. Successive wet years are critical for seedling growth, survival, and flowering (Rundel et al. 2007, p. 7). As with most desert species, water appears to be a limiting factor regarding abundance and populations trends. Huggins et al. (2012b, p. 11) found “a strong positive relationship between proportion population change and seasonal precipitation, suggesting that the observed population fluctuations for the Lane Mountain milk- vetch are controlled by inter-annual variation in precipitation.” The highest recruitment years during the study, 2005 and 2011, also had the highest precipitation (35.2 and 21.5 cm, respectively). Both of these high recruitment years were preceded by years of modest recruitment and precipitation around the wet period average (Huggins et al. 2012b p. 12). However, even in a wet year (2004–2005) on 1 study plot, Lane Mountain milk-vetch seedling survival to the following year was 16 percent (8 of 49 individuals) (Rundel et al. 2007, p. 7). Thus, Lane Mountain milk-vetch may require two or more consecutive years of above average precipitation to recruit new plants.

Based on data collected since 1999 on Lane Mountain milk-vetch population demographics in high density populations, Rundel et al. (2006, pp. 10–11) predicted that if there were no wet years (i.e., precipitation exceeding 6 in (150 mm) from October –May) in the next 19 years, all existing Lane Mountain milk-vetch plants in the monitored populations would die. In the past, the Mojave Desert had short and long-term climatic variation patterns for precipitation. The SOI influenced short-term precipitation and produced a wet year every 3 to 5 years. The PDO caused wet and dry periods every two to three decades. However, the last wet year occurred 8 years ago. This information indicates that the SOI historical patterns are currently not in effect and supports current climate change models that the Mojave Desert will be drier in the 21st century than in the past. For smaller populations, the time for the population to be extirpated would be less, about 10 to 15 years (Rundel et al. 2004, p. 17). This analysis assumed a long life span for the Lane Mountain milk-vetch, which most plants do not have. Huggins et al. (2010a, p. 127) reported that if drought conditions continue, it is possible that Lane Mountain milk-vetch numbers may erode further, leaving most, if not all populations in eminent danger of local extinction.

Effects to Nurse Shrubs: The current drought that began in 1999 has been documented to result in population diebacks (loss of number of plants) and drought pruning of perennial desert shrubs (reduction in canopy size) (Breshears et al. 2005, pp. 15144–15148; Hereford et al. 2006, pp. 13–34; Haymerlynck and Huxman 2009, pp. 582–585; and McAuliffe and Haymerlynck 2010, pp. 885–896). This current drought period has led to unusually high shrub mortality and canopy dieback in the Mojave Desert, including Lane Mountain milk-vetch population areas where shrub canopy deterioration and nurse shrub mortality have been high (Hereford et al. 2006, p. 30; Miriti et al. 2007, pp. 34–35; Haymerlynck and McAuliffe 2008, pp, 1798 and 1801; Huggins et al. 2010a, p. 125; Prigge et al. 2011, p. 183). Nurse shrubs for the Lane Mountain milk-vetch decreased in density and canopy cover; shrub mortality was high, and for the nurse shrubs that survived, the average nurse shrub lost 55 percent of its canopy cover during the current drought (Huggins et al. 2010c, p. 1). Huggins et al. (2012c, p. 100) reported that shrub mortality in Lane Mountain milk-vetch populations from 2000 to 2009 was 48 percent while recruitment was 5 percent.

Because of the nurse-protégé relationship between woody shrubs and Lane Mountain milk-vetch, the deterioration and loss of nurse shrub canopies due to drought would negatively affect protégé plants such as Lane Mountain milk-vetch. This conclusion is based on data that nurse shrub canopies provide shade, which affects the microclimate and water availability within and below nurse shrubs (Valiente-Banuet et al. 1991, Nolasco et al. 1997, Shumway 2000, Flores et al. 2004, Barchuk et al. 2005, Huggins et al. 2010, pp. 120–128; Huggins et al. 2012b, p. 15), and likely indirectly affects the establishment and survival of the Lane Mountain milk- vetch. This conclusion is supported by a study showing a significant decrease in survival of Lane Mountain milk-vetch plants among nurse shrubs with canopies reduced by drought (Huggins et al. 2010a, pp. 120–128; Huggins et al. 2012c, p. 98). Huggins et al. (2013c, p. 110) reported a significant difference between Lane Mountain milk-vetch plant survival for nurse shrubs with 75 percent intact canopy cover compared to 40 percent intact canopy cover. About twice the number of Lane Mountain milk-vetch plants survived with 75 percent cover as with 40 percent cover.

Canopy size of nurse shrubs is positively correlated with Lane Mountain milk-vetch plant size and flower and seed production. Reduced canopy size would result in reduced seed production and germination, low seedling survival, and reduced recruitment of new Lane Mountain milk-vetch plants (see Reduction in Seed Availability and Disruption of Seed Dispersal). In addition, seed density of Lane Mountain milk-vetch is low in the soil seed bank when compared to other desert shrubs (Rundel et al. 2009, pp. 15–16; Huggins et al. 2012a, p. 18), and seed dispersal beyond nurse shrub canopies is rare (Rundel et al. 2009, p. 18). A continuing drought in the Mojave Desert would result in additional nurse shrub mortality and canopy dieback that would lead to additional losses of Lane Mountain milk-vetch plants and local extirpations of populations (Huggins et al. 2010a, p. 127; Service 2011 CH 76 FR 29109).

The interruption of a drought by an unusually wet year is not adequate to reverse the loss of canopy cover and mortality of nurse shrubs, and therefore not adequate to reverse the loss of Lane Mountain milk-vetch plants. Nurse shrubs are slow growing woody perennials that take several years to regrow lost canopies from a drought and decades to germinate and re-establish from seed (Lovich and Bainbridge 1999, p. 311). Similarly, Lane Mountain milk-vetch does not reverse the loss of seed production, adult plants, seeds present in the seed bank, or recruitment of new plants with one wetter than normal year. Huggins et al. (2010a, p. 126) demonstrated that the unusual wet year of 2004–2005 did not produce additional Lane Mountain milk-vetch plants that survived. Rundel et al. (2007, p. 33) reported that both the amount and frequency of precipitation are crucial in maintaining a sustainable population of Lane Mountain milk-vetch and that more than two successive wet years are needed for Lane Mountain milk-vetch seeds to germinate and survive to adult plants (Rundel et al. (2007, p. 7).

Increases in Soil Losses: Higher temperatures and decreased soil moisture will likely reduce the stability of soil aggregates, making the surface more erodible. Rainfall events are expected to decrease in occurrence, but increase in intensity. Therefore, erosive water forces will increase during high-intensity runoff events, and wind erosion will increase during intervening dry periods (Archer and Predick 2008, pp. 25–26). Decreases in vegetation cover, due to lower precipitation and disturbances such as fire or vehicle activity, coupled with increases in wind speed and gustiness, will further increase wind erosion (Archer and Predick 2008, pp. 25–26). Nitrogen is typically removed from the system during rain events or wind erosion, so increased wind and water erosion will result in a net nitrogen removal from the system (Archer and Predick 2008, pp. 25–26).

Reduction in Nutrient Cycling: Intensification of the hydrologic cycle due to atmospheric warming is expected to reduce rainfall frequency, but increase the intensity and/or size of individual precipitation events (Archer and Predick 2008, p. 25) when precipitation occurs. Reducing the frequency of precipitation reduces the wet–dry cycles in soils. This reduction retards microbial activity and nutrient cycling, likely introducing a long-term nitrogen limitation to plant growth. For winter rainfall ecosystems such as the western Mojave Desert, shifts in wet–dry cycles are known to cause reductions in net primary production (the rate of photosynthesis minus respiration in plants) (Archer and Predick 2008, p. 25), that is, a reduction in plant growth.

Nonnative Species Are Likely to Increase in Abundance: In a wet year (such as 2004– 2005), increased precipitation and perhaps timing of precipitation stimulated unusually vigorous nonnative weed growth under and around Lane Mountain milk-vetch nurse shrub canopies, and inhibited milk-vetch seedling growth and perhaps seed germination (Rundel et al. 2007, p. 7). A series of wet years is crucial for Lane Mountain milk-vetch seedling establishment and recruitment, but it also promotes the germination and growth of nonnative invasive annual plants that compete with and promote the herbivory (predation) of Lane Mountain milk-vetch seedlings (Rundel et al. 2007, p. 7). When an infrequent wet year occurs, the Lane Mountain milk-vetch must now compete with nonnative invasive plant species for space, water, nutrients, and sunlight. The effects of climate change may also lead to an increase in abundance of nonnative species (Archer and Predick 2008, p. 26).

Nonnative invasive plants negatively impact native shrub communities in the Mojave Desert by competing with native forbs and shrubs for water and soil nitrogen, inhibiting germination of natives through densely-packed stands of seedlings and accumulated plant litter, and initiating germination and growth earlier than natives (Brooks 2000, pp. 103–105; Booth et al. 2003, pp. 36–48; DeFalco et al. 2007, 302–305). Non-native plant litter may impede germination of native plant seeds by reducing the amount of water that reaches the soil, and suspending native seeds above and out of contact with the soil (Brooks and Esque 2002, p. 333). Brooks and Berry (2006, p. 114) reported that while invasive nonnative plants contribute relatively few species to the annual plant flora in the Mojave Desert, they comprise the vast majority of the total annual plant community biomass in the Mojave Desert.

Fire Frequency, Size, and Intensity Is Expected to Increase: The recent invasion of nonnative annual grasses into the desert bioregion of the southwestern U.S. introduced new fuel conditions. Nonnative species such as red brome (Bromus madritensis), cheatgrass (Bromus tectorum) and Mediterranean grass (Schismus arabicus and S. barbatus) provide more lasting and less patchy fine fuelbeds than native annual plants, persisting longer into the summer and subsequent years (Brooks 1999, pp. 17–18; Brooks and Matchett 2006, 148–164). In years of high winter rainfall in the Mojave Desert, these nonnative invasive annual grasses produce a carpet of vegetation that fill interspaces between woody shrubs with continuous fine fuels and facilitate the spread of fire between woody shrubs and across large areas (Brooks and Matchett 2006, p. 149).

Once established, nonnative invasive plant species can promote and accelerate the fire cycle in a self-reinforcing manner. The slow growth and episodic nature of recruitment of many native desert plant species constrains recovery from frequent fires that accompany the establishment of nonnative invasive grasses. The result is the potential for native desert vegetation communities to be transformed quickly and radically into near monocultures of nonnative invasive species over large areas (Archer and Predick 2008, p. 26; Chambers and Pellant 2008, pp. 29–33).

As mentioned earlier, the annual number of fires in the Mojave Desert increased significantly between 1980 and 1995 (Brooks and Esque 2002, p. 334) with some researchers predicting this trend to continue (Knapp 1998, pp. 259–272; Smith et al. 1987, 139–143; Smith et al. 2000, pp. 79–82; Fenstermaker 2012, p. 1).

Response of Lane Mountain Milk-vetch to Drought and Climate Change

Due to the uncertainties of current climate projection models, the lack of models for projecting climate change for relatively small geographic areas, the complexity of interacting factors that may influence vegetation changes, and the uncertainty regarding the effects of climate change on the Lane Mountain milk-vetch’s reproduction, recruitment, and dispersal behaviors, we have limited information on which to base meaningful predictions on how climate change may influence the duration or severity of drought within the range of the Lane Mountain milk-vetch other than it would likely be more severe than experienced historically. We know that the status of the Lane Mountain milk-vetch has been affected by long-term drought from the data collected on Lane Mountain milk-vetch populations from 1999 to present.

Based on the information discussed above, we acknowledge that temperatures in the western Mojave Desert where the Lane Mountain milk-vetch occurs have increased and are likely to continue increasing. We also acknowledge that, if hotter and drier summers and more extreme weather patterns in temperature and precipitation occur within its range, the Lane Mountain milk-vetch would be negatively affected. We base this conclusion on the following information about the requirements of the Lane Mountain milk-vetch and its habitat. As discussed in the “Species Biology and Habitat Characteristics” sections, Lane Mountain milk- vetch begins regrowth in the late fall or winter, once sufficient soil moisture is available. Established individuals become dormant in the late spring or summer when soil moisture has been depleted. The successful seed production, germination, seedling survival, and regrowth of Lane Mountain milk-vetch plants depend on the availability of sufficient soil moisture. The amount, timing, and frequency of precipitation required for each of these stages (e.g., germination versus seedling survival) can be different. We assume that if the projection that temperatures will increase in the future is true, the evaporation rate of moisture from the soil and evapotranspiration rate from Lane Mountain milk-vetch plants and nurse shrubs would increase, requiring greater amounts of soil moisture from precipitation to persist. The Lane Mountain milk-vetch could respond to more extreme weather patterns in amount, timing, and frequency in one or more ways. If precipitation declines or the timing and frequency of precipitation is reduced or altered such that it results in inadequate availability of soil moisture during key periods (e.g., summer for seedling survival, or late fall and winter for seed production), this changed pattern would reduce seed production, seed germination, seedling survival, and regrowth of the Lane Mountain milk-vetch. If the reduced precipitation rates and changed patterns persist, the habitat requirements of the Lane Mountain milk-vetch, including the presence of nurse shrubs, may no longer be present.

Based on the known specific habitat requirements of the Lane Mountain milk-vetch and historical response to drought conditions, this narrow endemic species could respond to ambient temperature increases and precipitation decreases (that is, drought conditions of greater intensity and/or duration than historically recorded) in three general ways: (1) Stay in place; (2) move farther north; or (3) move higher in elevation.

Staying in place would likely mean Lane Mountain milk-vetch population numbers would decrease and smaller populations may disappear resulting in a distribution smaller than its current limited distribution. If drought conditions continue, it is possible that Lane Mountain

milk-vetch numbers may erode further, leaving most, if not all populations in eminent danger of local extinction (Huggins et al, 2010a, p. 127). Unfortunately, regional climate indicators suggest that the Mojave Desert may remain dry for 1 to 2 decades or longer (Breshears et al. 2005; Hereford et al. 2006, 13–34; Huggins et al. 2010a, p. 127).

Moving farther north or to higher elevations to a cooler, wetter climate would require that suitable habitat (specific soils and vegetation) are available and that seed dispersal mechanisms would be able to transport viable Lane Mountain milk-vetch seed to these areas. The limited information we have on seed dispersal mechanisms indicates wind, water, and ants would disperse Lane Mountain milk-vetch seeds a short distance, but rodents and possibly birds are the more likely to disperse seeds for longer distances. However, Huggins et al. (2010a, p. 127) reported that Lane Mountain milk-vetch seed density is low to extremely low in the soil seed bank compared to other desert shrubs, and seed dispersal beyond nurse shrub canopies of the seed producing milk-vetch plant is rare (Sharifi et al. 2009b, p. 9). We hypothesize that seed dispersal through creosote or creosote-burrobush vegetation communities to other mixed scrub vegetation communities would be rarer.

With respect to the current location of the four Lane Mountain milk-vetch populations, we know that if rodents dispersed seed, this dispersal would be limited. Rodents typically have small home range sizes; larger rodents have larger home ranges than smaller species. A large rodent in the range of the Lane Mountain milk-vetch, the Mohave ground squirrel, has a home range size that varies from 0.72 to 26.7 ac (0.29 to 10.8 ha) (Harris and Leitner 2004, pp. 517 and 521). Therefore, the likelihood of seed dispersal across 0.7 to 1.3 mi (1.1 to 2.1 km), which is the closest distance between current Lane Mountain milk-vetch populations, is limited or unlikely. This closest distance may increase to 2.1 and 2.5 mi (3.4 and 4.0 km) with the implementation of military training and operations activities in the Western Expansion Area. This information points to birds as the only possible long-distance vector for dispersal of Lane Mountain milk-vetch seeds to move north or higher in elevation. Birds have not been documented as a vector for seed dispersal for Lane Mountain milk-vetch. Coupled with the low density of seed in the soil seed bank, this information indicates that longer distance seed dispersal by birds is possible but not likely for Lane Mountain milk-vetch.

While many plant species are capable of adjusting their elevational range in response to climate change, the Lane Mountain milk-vetch’s unique habitat requirements make dispersal to higher elevations or farther north difficult because its habitat is patchy and restricted in distribution, and its dispersal is low (Rundel et al. 2009, p. 18). Without the capacity to adjust its range in relation to climate, the persistence and recovery of the Lane Mountain milk-vetch most likely is limited to existing population sites (Huggins et al. 2012a, p. 2). Therefore, the most likely response by the Lane Mountain milk-vetch to climate change would be to constrict its range. However, we cannot be certain that the Lane Mountain milk-vetch will respond this way. Regardless of the species’ response to ambient temperature increases and precipitation declines, ultimately the range of the species will likely be smaller than it is currently.

Lane Mountain milk-vetch has evolved several adaptations to persist in an environment with periodic drought. These adaptations include growing under the canopy of nurse shrubs that provide shelter from high temperatures and low moisture, limiting or curtailing the production of

flowers and seeds, remaining dormant during the drier years with no above-ground vegetative growth, having viable seeds for at least 5 years, and requiring sufficient amounts of water for seed germination and new plant recruitment.

However, prolonged drought exacerbates the effects of drought on the Lane Mountain milk-vetch and is likely to result in reduced reproduction, little or no recruitment, and elevated mortality. While the Lane Mountain milk-vetch is adapted to periodic drought, it may be not adapted to prolonged drought. If so, this situation can result in the severe reduction or extirpation of the Lane Mountain milk-vetch in local areas.

Lane Mountain milk-vetch populations at the Goldstone and Brinkman Wash-Montana Mine locations have experienced substantial population declines (Huggins et al. 20103, p. 123). In 2009, Lane Mountain milk-vetch populations were less than 12 percent of their size in 1999, leaving a number of populations at “critically low levels,” and in “danger of local extinction” (Huggins et al. 2011, p. 6). In 2010, these declines stabilized but not before leaving many populations depleted and vulnerable to local extinction (Huggins et al. 2011, p. 3). These substantial population declines have occurred simultaneously with recent severe drought conditions in the Mojave Desert that began in 1999 (Huggins et al. 2011, p. 7).

The current drought conditions in the western Mojave Desert are likely to represent the first part of an historic pattern of 20- to 30-year dry periods in the Mojave Desert. This likely means that the Lane Mountain milk-vetch is in a decreasing phase of a population cycle driven by alternating climate periods that are wetter and drier than normal (Huggins et al. 2012, p. 2). If Lane Mountain milk-vetch populations are following climate cycles, populations should remain at their current low-population levels until the onset of the next wet period in 10 to 20 years, and then gradually increase (Huggins et al. 2012, p. 2). This hypothesis assumes that the conditions of the past will continue unaltered in the future. Alternately, drought conditions since 1999 may represent the evolution of a novel climate in the Mojave Desert as the result of global climate change processes (Hoerling and Kumar 2003, p. 694). If so, dry conditions in the Mojave Desert could continue for an indefinite period, as projected by global climate change-type drought (Cook et al. 2004, p. 1018; Breshears et al. 2005, p. 15148; Seager et al. 2007, p. 1183–1184; Huggins et al. 2012b, p. 6). If correct, then some form of conservation intervention would likely be needed to maintain Lane Mountain milk-vetch populations during the climate change drought (Huggins et al. 2012, p. 2).

Climate change will occur concurrently with other environmental factors: The response of arid lands to climate change will be strongly influenced by interactions with non-climatic factors, such as land use and nonnative species abundance. Because many factors affect ecosystems simultaneously, the synergistic effects of these interacting factors often differ from the sum of the separate effects. Thus, climate effects should be viewed as the backdrop against which other factors act, and simple generalizations regarding climate effects should be viewed with caution (Archer and Predick 2008, p. 26).

Summary of Climate Change Effects

The current prognosis for climate change impacts on the Southwest include fewer frost days; warmer temperatures; greater water demand by plants, animals, and people; and an increased frequency of extreme weather events (heat waves, droughts, and floods). Furthermore, warmer nights and projected declines in snow pack, coupled with earlier spring snow melt, will reduce water supply, lengthen the dry season, create conditions for drought and insect outbreaks, and increase the frequency and intensity of wildfires. Temperatures currently considered unusually high will occur more frequently (Archer and Predick 2008, p. 23).

In summary, within the range of the Lane Mountain milk-vetch, the potential effects of climate change, its magnitude, and projections on how the species will react are currently speculative for several reasons, including the uncertainties of climate projection models, the lack of models for projecting climate change for relatively small geographic areas, the complexity of interacting factors that may influence vegetation changes, and the uncertainty regarding the effects of climate change on the Lane Mountain milk-vetch’s reproduction, recruitment, and dispersal behaviors. Although climate change may have some effect on the species, at this time we cannot make meaningful projections on either how the climate within the range of the Lane Mountain milk-vetch may change, or how the species may react to climate change. The Lane Mountain milk-vetch has survived several periods of drought in the 20th century, including a 5- year drought in the early 20th century, and has evolved several adaptations to persist in an environment with drought as a natural feature of its environment. However, if these drought conditions increase in duration or severity in the future as predicted by climate change models, based on the best available scientific data, we conclude that the range of the Lane Mountain milk-vetch would constrict further, resulting in smaller and fewer populations.

Small Number of Individuals and Populations

Species that are endemic to small areas are inherently more vulnerable to extinction than are widespread species, because of the increased risk of genetic bottlenecks; random demographic fluctuations; climate change effects; and localized catastrophes, such as drought and fire (Pimm et al. 1988, p. 757; Mangel and Tier 1994, p. 607). For example, in 2013, a human-ignited fire burned all of the five known populations of Verity’s liveforever (Dudlea verityi), a threatened plant in southern California. In this case, a single random event adversely affected an entire species estimated to be about 1,500 plants (University of California, Santa Cruz 2013, p. 1). These problems are further magnified when these geographically restricted and small numbers of populations contain small numbers of individuals in these populations. Populations with these characteristics face an increased likelihood of stochastic (random) extinction due to changes in demography, the environment, genetics, or other factors (Gilpin and Soule´ 1986, pp. 24–34). Small, isolated populations often exhibit reduced levels of genetic variability, which diminishes the species’ capacity to adapt and respond to environmental changes, thereby lessening the probability of long-term persistence (e.g., Barrett and Kohn 1991, p. 4; Newman and Pilson 1997, p. 361) and which has been documented for the Lane Mountain milk-vetch. Small, isolated populations are also more susceptible to reduced reproductive vigor due to ineffective pollination and inbreeding depression, with the former documented for the species and the latter suggested from research results. The problems associated with small

population size and vulnerability to random demographic fluctuations or natural catastrophes are further magnified by synergistic interactions with other threats, such as those discussed above.

Currently, each of the four populations of Lane Mountain milk-vetch range in estimated population size from 209 plants for the Goldstone population to 544 plants at Coolgardie Mesa population. With this limited number of individuals, little documented recruitment in 13 years, and substantial population declines, these populations are vulnerable to extinction due to threats associated with small population size, small number of populations, or isolation between populations. These threats include loss of individual plants and degradation or loss of habitat from anthropogenic dust, drought, invasion from nonnative invasive plants, fire and associated vegetation type conversion, and climate change and threaten all four populations. In addition, the Coolgardie Mesa population is threatened by habitat degradation and loss from mining and OHV activities, the Paradise Valley population from military training and operations, mining and OHV activities, and the Brinkman Wash-Montana Mine population from military training and operations activities.

Combination of Factors and Synergistic Impacts

Many of the impacts described in this report may cumulatively affect the Lane Mountain milk-vetch beyond the scope of each individual threat. In this report, we identified multiple threats that may have interrelated impacts on Lane Mountain milk-vetch. For example, the future loss of additional significant mixed scrub habitat due to fire in the range of the Lane Mountain milk-vetch is anticipated because of the increasing cumulative interactions among human activities, nonnative invasive species, drought, and climate change, and because it has occurred in other areas in the Mojave Desert. As another example, OHV activities on military and BLM lands for training and recreational purposes alone may only directly impact a portion of the Lane Mountain milk-vetch populations. However, when combined with anthropogenic dust and associated physiological stress on Lane Mountain milk-vetch and nurse shrubs, the spread and proliferation of nonnative invasive species, drought and climate change, and fire, these threats may collectively result in a substantial reduction in Lane Mountain milk-vetch populations; habitat loss and degradation; fragmentation within and among the four populations; reduced seed production, dispersal and gene exchange (or genetic isolation); and reduced population persistence from natural random events. These scenarios represent two of many that are likely acting cumulatively to further contribute to the challenge of the Lane Mountain milk- vetch to survive and persist into the future in the Mojave Desert.

Climate change is a recent threat added to the existing threats from direct human impacts (e.g., military training, mining, and OHV activities). According to all models, it will exert increasing physiological and physical stressors on Lane Mountain milk-vetch than the species has experienced in the past. The predicted increase in temperature and drought intensity in this part of the Mojave Desert from climate change along with the increasing magnitude and intensity of other threats described in this report likely act in a synergistic manner, exerting greater stress on the Lane Mountain milk-vetch than the sum of the threats. While the combination of threats impacts the existence of Lane Mountain milk-vetch, we are unable to determine the precise magnitude or extent of cumulative or synergistic effects of the combination of factors on the viability of the species at this time.

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Summary of Analysis of Existing Regulatory Mechanisms:

At the time of listing, the primary threat to Lane Mountain milk-vetch was alteration and destruction of habitat due to military training, OHV recreation, mining, and change in fire regime. We discussed that the regulatory mechanisms that might provide some protection for Lane Mountain milk-vetch and its habitat included: the Federal Endangered Species Act, in those cases where the species occurs in habitat where it overlapped with ESA protections invoked for the federally threatened desert tortoise (Gopherus aggasiz), the Federal Land Policy and Management Act, and regional planning efforts, specifically the California Desert Conservation Area Plan (BLM 1980). Of particular concern was the limited ability of the BLM to regulate surface mining on public lands claimed under the Mining Laws of 1872.

Since the time of listing, several changes have occurred. On January 11, 2002, approximately half the habitat that supports Lane Mountain milk-vetch was transferred from BLM to the Army (P.L. 107-107). Of the area that supports Lane Mountain milk-vetch, 3,340 ac (1,352 ha) was to be used for high-use military training, 2,000 ac (809 ha) was to be used for medium-use military training, and 6,772 ac (2,740 ha) was to be fenced off and designated as conservation areas in Goldstone (2,470 ac [1,000 ha]) and East Paradise (4,302 ac [1,741 ha]). The Army has recently completed an Integrated Natural Resources Management Plan (INRMP) for Fort Irwin that more specifically outlines the management prescriptions for each of these areas (U.S. Department of the Army 2006).

The BLM has completed a California Desert Conservation Area (CDCA) Plan amendment, referred to as the West Mojave Plan (BLM 2005). Through the West Mojave Plan, habitat for the Coolgardie population of Lane Mountain milk-vetch and the westernmost fringe of the Paradise population were designated as an Areas of Critical Environmental Concern (ACECs), and the BLM committed to management prescriptions for these areas (BLM 2005). Although the BLM recommended withdrawing the ACECs from further mineral entry, the rights to existing mining claims still stand unless subject to an invalidation process by the BLM. Therefore, mining activity may continue at specific locations under the West Mojave Plan.

In light of these changes, this section summarizes whether threats to Lane Mountain milk-vetch are adequately addressed by existing regulatory mechanisms. In addition to reviewing the current status of these regulatory mechanisms, we also considered whether any additional laws and regulations provide a benefit to Lane Mountain milk-vetch and its habitat. These are organized below as follows: (1) Local land use ordinances and processes; (2) State laws and regulations; and (3) other Federal laws and regulations. Threats to the habitat continue to affect the species and may be exacerbated when not addressed by existing regulatory mechanisms, or when the existing mechanisms are not adequate (or not adequately implemented or enforced).

Local Land Use Ordinances and Processes

Currently, less than 1 percent of the range of the Lane Mountain milk-vetch is privately owned. In the past, this number was higher, but the Army recently purchased most of the private lands in the known distribution of the Lane Mountain milk-vetch in the Coolgardie Mesa and

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West Paradise Conservation Areas. The County of San Bernardino (County) has regulatory authority of these lands. However, sensitive species are usually not considered when undertaking actions such as issuing building or grading permits because the County considers these actions ministerial and not discretionary. Ministerial actions are excluded from the requirement for analysis under the California Environmental Quality Act (see State Laws and Regulations).

State Laws and Regulations

Two California laws and their implementing regulations have a potential to benefit the Lane Mountain milk-vetch, the California Environmental Quality Act (CEQA) (California (Public Resources Code sections 21000–21177)) and the State Mining and Reclamation Act (SMARA) (add code). In both cases, the lead agency reviewing potential projects on private lands for compliance would be the County of San Bernardino. However, the degree to which these state regulatory mechanisms would contribute to alleviating threats to Lane Mountain milk- vetch is likely low. To date, we are not aware of any instances in which the County has implemented any specific conservation measures for Lane Mountain milk-vetch in reviewing projects under their purview.

Federal Laws, Regulations, and Policies

Two Federal agencies are responsible for managing about 99 percent of the lands on which the Lane Mountain milk-vetch occurs, the Army and the BLM (see Distribution, Figure 3); therefore, Federal laws and regulations provide the greatest opportunity to have a benefit to the conservation of Lane Mountain milk-vetch and its habitat. The most important of these are: the Endangered Species Act (16 U.S.C. 1531–1544), as amended (Act); the Sikes Act Improvement Act (16 U.S.C. 670a–670o), as amended (Sikes Act); and the Federal Land Policy and Management Act of 1976 (43 U.S.C. 1701 et seq.) (FLPMA). The Army and BLM must also comply with the National Environmental Policy Act of 1970 (NEPA; 42 U.S.C. 4321 et seq.) for projects they fund, authorize, or carry out. NEPA require full evaluation and disclosure of information regarding the effects of contemplated Federal actions on sensitive species and their habitats, including federally listed species; however, it does not itself regulate activities that might affect such species, so we do not discuss it further here.

Endangered Species Act: Since the Lane Mountain milk-vetch was listed as endangered, the Act has been and continues to be the primary Federal law that affords protection to the species. The Service’s responsibilities in administering the Act include sections 7, 9, and 10. Section 7(a)(1) of the Act requires all Federal agencies, including the Army and the BLM, to utilize their authorities in furtherance of the purposes of the Act by carrying out programs for the conservation of endangered and threatened species. Section 7(a)(2) of the Act requires Federal agencies, including the Service, the Army, and BLM, to ensure that actions they fund, authorize, or carry out do not ‘‘jeopardize’’ the continued existence of a listed species or result in the destruction or adverse modification of habitat in areas designated by the Service to be critical. A jeopardy determination is made for a project that is reasonably expected, either directly or indirectly, to appreciably reduce the likelihood of both the survival and recovery of a listed species in the wild by reducing its reproduction, numbers, or distribution (50 CFR 402.02).

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A non-jeopardy opinion may include reasonable and prudent measures that minimize the extent of impacts to listed species associated with a project. Under section 9(a)(2) of the Act, with respect to endangered plant taxa, it is unlawful to remove and reduce to possession (collect) any such taxon from areas under Federal jurisdiction; maliciously damage or destroy any such taxon on any such area; or remove, cut, dig up, or damage or destroy any such species on any other area in knowing violation of any law or regulation of any State or in the course of any violation of a State criminal trespass law.

In 2011, the Service designated critical habitat for the species (76 FR 29108 to 29129). Critical habitat is a specific geographic area(s) that is essential for the conservation of a threatened or endangered species and that may require special management and protection. Critical habitat for the Lane Mountain milk-vetch includes BLM-managed lands and private lands for the entire Coolgardie Mesa population and for the western sliver of the Paradise Valley population. No critical habitat was designated for the Lane Mountain milk-vetch on Fort Irwin because of the 4(a)(3)(b) exemption in the Act (see discussion on Sikes Act below).

Consultation History: Since the Lane Mountain milk-vetch was first listed in 1998, the Army has consulted and coordinated with us regarding the effects of various activities on the species. In April 2004, we completed a biological opinion describing the impact of the Army’s military training program proposed in the western expansion area of Fort Irwin. We considered the status and distribution of Lane Mountain milk-vetch, the various management strategies, and the avoidance and minimization measures in place and those the Army would implement with the new plan. Many of the conservation recommendations in the biological opinion have been implemented.

By letter dated December 27, 2011, the Army (2011) informed us that it had decided “not to pursue training activities in the Superior Valley parcel (western expansion area). At some point in the future, following completion of the Army warfighting doctrine analysis, the Army will reassess its training needs. If, at that time, the Army determines that use of the Superior Valley Parcel is needed for training activities, it will consult with the Service as appropriate.” The Army is undertaking this course of action because of “the current flux in the (Department of Defense) budget, the withdrawal of United States military forces from around the world and the ongoing review and analysis of current Army warfighting doctrine” (Army 2012e). The change in the Army’s proposed action eliminated imminent impacts from military training from all areas where Lane Mountain milk-vetch occurs on Fort Irwin.

The Army has used its authorities to carry out programs for the conservation of the Lane Mountain milk-vetch. It has acquired private lands (absent mineral rights) in the Coolgardie Mesa and Paradise Valley populations of the Lane Mountain milk-vetch from willing sellers with the intention of transferring these lands to the BLM at a future date. These lands would then be managed under the BLM’s CDCA plan and amendments. The Service has issued permits and the Army has funded and implemented studies and research on the Lane Mountain milk-vetch including monitoring the status of the species; researching genetics, pollinators, and reproduction ecology; exploring captive propagation; gathering information on demographics and ecology; and modeling Lane Mountain milk-vetch populations to predict the long-term viability.

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If any discretionary actions are proposed in the future on these Federal lands, with the exception of certain mining activities, these discretionary actions would be subject to consultation with the Service to ensure that the proposed actions are not likely to jeopardize the continued existence of the Lane Mountain milk-vetch or adversely modify designated critical habitat.

Sikes Act Improvement Act: An INRMP is a requirement of the Sikes Act Improvement Act (16 U.S.C. 670a–670o), as amended (Sikes Act). First passed in September 1960, the Sikes Act authorizes the DOD to manage the natural resources under its stewardship. To do this, the Sikes Act requires that the DOD develop comprehensive INRMPs that are fully coordinated with the U.S. Fish and Wildlife Service and the appropriate state natural resource agency. An INRMP integrates the implementation of the military mission at each military base with stewardship of the natural resources found on the base. Each INRMP includes: (1) An assessment of the ecological needs on the installation, including the need to provide for the conservation of listed species; (2) A statement of goals and priorities; (3) A detailed description of management actions to be implemented to provide for these ecological needs; and (4) A monitoring and adaptive management plan. Among other things, each INRMP must, to the extent appropriate and applicable, provide for fish and wildlife management, fish and wildlife habitat enhancement or modification, wetland protection, enhancement, and restoration where necessary to support fish and wildlife, and enforcement of applicable natural resource laws.

As discussed above, the Army completed the Western Expansion project at Fort Irwin (Service 2005). This project addressed the direct and indirect impacts to the Lane Mountain milk-vetch and its habitat from the proposed expansion of the Fort Irwin boundaries and conducting military training and operations activities in the expansion area, and mitigation it would implement to reduce the adverse effects to the Lane Mountain milk-vetch from the expansion and activities. These mitigation measures were incorporated into Fort Irwin’s Integrated Natural Resources Management Plan (INRMP) (Army 2005).

Army lands within the boundaries of the NTC at Fort Irwin are subject to an INRMP for 2006-2011 (Army 2005), which includes management guidelines for Lane Mountain milk-vetch. The INRMP included sections on conservation, monitoring, and adaptive management for the Lane Mountain milk-vetch. Goals for the Lane Mountain milk-vetch included protecting Lane Mountain milk-vetch populations, conserving habitat, and supporting research programs and studies.

Fort Irwin established three special management areas for the three Lane Mountain milk- vetch populations within the recently expanded Fort Irwin boundary. These management areas were established to help protect Lane Mountain milk-vetch populations and conserve habitat:

1. The NTC-Gemini Conservation Area was established to encompass most of the Goldstone population (Army2005, p. 92). 2. The East Paradise Conservation Area was established to include 80 percent of this population; it is connected to the West Paradise Conservation Area, an ACEC established by the BLM (BLM et al.2005, Chapter 2, p. 217). 3. The Brinkman Wash Restricted Access Area was established to include 51 percent of the Brinkman Wash-Montana Mine population (Army 2006, p. 92).

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As discussed above, the Army will not be pursuing military training activities at this time (Army 2011); therefore, the remaining 20 percent of the Paradise Valley and 49 percent of the Brinkman Wash-Montana Mine populations proposed for military training will not be subject to habitat disturbance at this time.

On Fort Irwin, the Army allows certain activities to occur within the special management areas for the Lane Mountain milk-vetch. For the NTC-Gemini Conservation Area and East Paradise Conservation Area, use of authorized roads would continue. During military training, observer teams are authorized to find and reorient military training units moving within Fort Irwin who are unfamiliar with the terrain and authorized travel routes of Fort Irwin to prevent unnecessary habitat destruction (Army 2006, p. 92). At the Brinkman Wash Restricted Access Area, construction and operation of non-combat but ground disturbing activities is authorized. These activities include construction and operation of small communication towers and observation decks. Before training begins, the Army will close all unnecessary and redundant routes in the Brinkman Wash restricted Access Area using methods such as signage and vertical mulching (Army 2005, pp. 92–93).

The Fort Irwin INRMP identified specific tasks to implement during 2006-2011 to protect Lane Mountain milk-vetch populations and conserve habitat both on and off Fort Irwin. Within the Fort Irwin boundary, these tasks included installing fences and signs to prevent or deter unnecessary incursions into adjacent habitat (Army 2006, p. 89) and prohibiting off-road travel in Conservation Areas and the Restricted Access Area (Army 2005, p. 93). Outside Fort Irwin, these tasks included acquiring private lands in the area of the Coolgardie Mesa population to prevent future habitat disturbance to this population (Army 2006, p. 99) and contributing to the cost of route closures and rehabilitation actions in the BLM’s proposed Lane Mountain milk- vetch ACEC (Army 2005, p. 93).

The research program and studies included supporting research to monitor the Lane Mountain milk-vetch; exploring the feasibility of Lane Mountain milk-vetch propagation; gathering information on demographics, life history, and ecology; and considering population modeling to predict the long-term viability of the Lane Mountain milk-vetch (Army 2005, p. 96). The results of this program would lead to improved management strategies for the Lane Mountain milk-vetch (Army 2005, p. 96). The monitoring program includes several tasks regarding road closures, fencing, signage, dust levels, controlling invasive plants, and unauthorized surface disturbance in special management areas for the Lane Mountain milk-vetch (Army 2005, pp. 98–101). The adaptive management program includes an internal review by Fort Irwin personnel and an annual interagency review with the Service to discuss research progress, monitoring trends, and determine if management changes are needed (Army 2005, p. 101).

Many of these tasks have been partially or fully implemented. The NTC-Gemini Conservation Area adjacent to the southern boundary of the Goldstone Complex was fenced in 2003, restricting most vehicle traffic. In October 2005, the eastern and western perimeter fences of this area were moved 1,640 ft (500 m) to the east (Army 2005, pp. 91–92). This conservation area is fenced, signed, and off-limits to military activities (Hessing and Shaughnessy 2011, p. 31).

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The East Paradise Conservation Area and Brinkman Wash Restricted Access Area have been partially fenced with barbed wire and signed. In 2010, the gates at the boundary between the Western Expansion Area, where the East Paradise Conservation Area and Brinkman Wash Restricted Access Area are located, and BLM-managed land to the south were locked to prevent public entry. The locked gates and Range Control oversight have decreased traffic in the East Paradise Conservation Area, although ORV tracks continue to be found in the Lane Mountain milk-vetch study plots in the East Paradise Conservation Area and the Brinkman Wash Restricted Access Area. Based on casual observations by Fort Irwin’s personnel, ORV activity appears to be increasing in the East Paradise Conservation Area and Brinkman Wash Restricted Access Area, despite off-limits signage that has been erected along the border of these areas (Hessing and Shaughnessy 2011, p. 31).

The Army has purchased several parcels of private land in the Coolgardie Mesa and Paradise Valley populations of the Lane Mountain milk-vetch outside the Western Expansion Area and within the boundaries of BLM’s Coolgardie Mesa and West Paradise Conservation Areas. The Army has not received a request from the BLM to accept assistance regarding implementations of route closures and associated rehabilitation actions in the BLM’s Coolgardie Mesa and West Paradise Conservation Areas as offered to the BLM by the Army.

The Army has funded research and studies on the Lane Mountain milk-vetch. Some of these studies are ongoing. The research and studies included monitoring the Lane Mountain milk-vetch; exploring Lane Mountain milk-vetch propagation in greenhouse conditions; gathering information on demographics, life history, and ecology; and using this information to project the long-term viability of the Lane Mountain milk-vetch (see Species Biology section above).

There is no information on whether some of the monitoring or adaptive management actions within the INRMP are being implemented to minimize or avoid adverse effects to the Lane Mountain milk-vetch in the special management areas. There is no available information that the Army is monitoring road use, OHV use, dust deposition, or invasive plants in Lane Mountain milk-vetch habitat, or if they monitor and maintain fences and signage in special management areas for the Lane Mountain milk-vetch. For example, there is no information that the Army has modified their management actions to correct the unauthorized ORV activity at the East Paradise Conservation Area or the Brinkman Wash Restricted Access Area.

Federal Land Policy and Management Act: The Federal Land Policy and Management Act of 1976 (FLPMA) (43 U.S.C. 1701 et seq.) is the primary Federal law governing most land uses on BLM lands. FLPMA established a public land policy for the BLM; it provides for the management, protection, development, and enhancement of the BLM lands. FLPMA directs that public lands be managed for multiple use and sustained yield. Under its multiple use mandate, the BLM allows grazing, mining, OHV use, energy production, and other uses on public lands. FLPMA also requires that “the public lands be managed in a manner that will protect the quality of scientific, scenic, historical, ecological, environmental, air and atmospheric, water resource, and archeological values; that…will preserve and protect certain public lands in their natural condition; (and) that will provide food and habitat for fish and wildlife….” Furthermore, it is the policy of the BLM “to manage habitat with emphasis on ecosystems to ensure self-sustaining

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populations and a natural abundance and diversity of wildlife, fish, and plant resources on public lands” (BLM manual 6500.06). The BLM also has the flexibility under FLPMA to establish and implement special management areas such as ACECs and research natural areas, where the BLM can limit or exclude surface disturbance activities that adversely affect sensitive species, such as the Mohave ground squirrel.

FLPMA directs the development and implementation of resource management plans (RMPs), which direct management at a local level, and requires public notice and participation in the formulation of such plans and programs for the management of BLM lands. RMPs authorize and establish allowable resource uses, resource condition goals and objectives to be attained, program constraints, general management practices and sequences, intervals and standards for monitoring and evaluating RMPs to determine effectiveness, and the need for amendment or revision (43 CFR 1601.0–5(k)).

Section 601 of FLPMA was written specifically for the CDCA, which includes the western Mojave Desert. In this section, Congress noted the fragility of the California desert ecosystem that is “easily scarred and slow to heal; the historical, scenic, archeological, environmental, biological, cultural, scientific, educational, recreational, and economic resources in the California desert; and that certain rare and endangered species of wildlife, plants, and fishes, and numerous archeological and historic sites, are seriously threatened by air pollution, inadequate Federal management authority, and pressures of increased use, particularly recreational use, which are certain to intensify because of the rapidly growing population of southern California.” Congress charged the BLM with developing and implementing a Resource Management Plan (RMP) for the CDCA that provides for the immediate and future protection and administration of the public lands in the California desert within the framework of a program of multiple-use and sustained yield, and the maintenance of environmental quality. Within the range of the Lane Mountain milk-vetch, the current BLM land management documents are the CDCA Plan 1980, as amended (BLM 1999) and other amendments to the CDCA Plan, including the West Mojave Plan and EIS (BLM et al. 2005). The West Mojave Plan is the RMP for the western portion of the CDCA.

The West Mojave Plan is the up to 30-year RMP whose boundary includes about 14,597 ac (5,907 ha) of the Coolgardie Mesa Conservation Area and West Paradise Conservation Area (BLM et al.2005, Executive Summary p. 12) of the current habitat of the Lane Mountain milk- vetch. The West Mojave Plan includes the goal of protecting viable unfragmented habitat throughout the limited range of the Lane Mountain milk-vetch, and the objectives of acquiring occupied habitat on private lands and minimizing potential impacts on public lands to the Lane Mountain milk-vetch (BLM et al. 2005, Chapter 2, p. 5)

In their 2005 West Mojave Plan, the BLM realized that because the military training and operations activities planned on Fort Irwin’s Western Expansion Area at that time may result in the loss of a substantial numbers of Lane Mountain milk-vetch plants and areas of habitat, the remaining habitat on BLM lands on the Coolgardie Mesa and the west side of the Paradise Range must be managed on a reserve-level basis (BLM et al. 2005, Chapter 4, p. 73). Therefore, as part of the plan amendment of the CDCA, the BLM in the West Mojave Plan established two Areas of Critical Environmental Concern (ACEC) for the Lane Mountain milk-vetch:

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1. The West Paradise Conservation Area comprises 1,243 ac (503 ha) (BLM et al. 2005, Chapter 2, p. 17), and is contiguous with the Army’s East Paradise Valley Conservation Area along the southwestern boundary of the NTC. This ACEC includes a sliver of the western portion of the Paradise Valley population of the Lane Mountain milk-vetch. 2. The Coolgardie Mesa Conservation Area comprises 13,354 ac (5,404 ha) (BLM et al. 2005, Chapter 2, p. 16), which includes the Coolgardie Mesa population of the Lane Mountain milk-vetch.

The boundaries of the Conservation Areas, which are in two separate blocks, include all known populations of the Lane Mountain milk-vetch and most of the granitic substrate on which they occur outside the Fort Irwin expansion area. Of these 14,597 ac (5,907 ha), 10, 164 ac (4,113 ha) are BLM lands (BLM et al. 2005, Chapter 2, p.108, Executive Summary, p. 12).

Under the West Mojave Plan, both ACECs would be managed to maintain habitat for the Lane Mountain milk-vetch with the following management prescriptions. The BLM lands within the ACEC boundaries are designated as land-use class L. These areas were previously designated as land-use class M. Class L lands are intended to support limited use of activities that degrade the value of the land and to protect sensitive, natural, scenic, ecological, and cultural resource values. Class M lands have moderate use, and provide for a controlled balance between higher intensity uses and resource protection (BLM et al. 2005, chapter 3, p. 3). The BLM would require botanical surveys prior to issuing any use permits. No permits would be issued which allow take of this species (projects would be relocated). No grazing would be permitted. Route designation would identify acceptable open routes of travel. The 6 mi (10 km) of closed routes (BLM et al. 2005, Chapter 2, p. 162) would have a high priority for obliteration. Fencing of the approved closed routes would be installed, as necessary, with signs advising the public that the area is closed to vehicle travel because of endangered species conservation. All private lands within the West Paradise Conservation Area and occupied habitat occupied by the Lane Mountain milk-vetch in the Coolgardie Mesa Conservation Area would be acquired, to the extent feasible and from willing sellers only. Lands within the conservation areas would be withdrawn from mineral entry (subject to valid existing rights). Claimholders with valid existing rights would be compensated. Claim-holders would be notified of the presence of the endangered Lane Mountain milk-vetch. Restrictions on casual use mining that involve ground disturbance within the Coolgardie Mesa Conservation Area would be developed as necessary (BLM et al. 2005, Chapter 2, p. 108). The BLM would require a 5-to-1 mitigation ratio for land-disturbing projects and limit total future ground disturbance to 1 percent of the area of each ACEC (BLM et al. 2005, Chapter 2, pp. 11 and 16).

To date, the BLM has not implemented or completed most of these management actions identified in the West Mojave Plan on its lands that would conserve the Lane Mountain milk- vetch and its habitat or reduce threats from surface disturbance, with the exception that the Army has purchased private lands for eventual transfer to BLM. Although BLM established the two ACECs, management prescriptions intended to protect Lane Mountain milk-vetch and other resources from surface disturbance activities have not yet been implemented.

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In addition, the West Mojave Plan adopted minor modifications of the network of motorized vehicle access routes that were adopted as a component of the CDCA Plan by the BLM on June 30, 2003, which include route closures in the Lane Mountain milk-vetch ACECs, and amended the Motorized Vehicle Access Element’s Stopping and Parking section, incorporating restrictions within the Lane Mountain milk-vetch ACECs. The restrictions are: Motorized vehicle based camping is limited to previously existing disturbed camping areas adjacent to routes designated “open;” and motorized vehicle stopping and parking is allowed within 50 ft (15 m) of the centerline of routes designated “open” (BLM et al. 2005, Chapter 2, pp. 11 and 16). Fencing, if deemed necessary to protect Lane Mountain milk-vetch, could be implemented. Private lands that may be acquired would be withdrawn from mineral entry (BLM et al. 2005, Chapter 2, pp. 11 and 16). Although the BLM adopted these management prescriptions in 2005 through finalization of the West Mojave Plan, we have no information that these actions have been implemented or are being enforced. Although the West Mojave Plan says the BLM would withdraw the ACECs from further mineral entry, the rights to existing mining claims would still stand unless subject to an invalidation process by the BLM. Therefore, threats to Lane Mountain milk-vetch from mining activity remain.

Because the BLM manages their lands for multiple use, the CDCA Plan and amendments are written to limit or exclude activities. If a limitation or exclusion is not addressed in the CDCA Plan or an amendment, the activity is not prohibited. The West Mojave Plan did not prohibit renewable energy development in the CDCA’s ACECs; however, other BLM policies restrict renewable energy development in the two Lane Mountain milk-vetch ACECs (see below). In addition, FLPMA does not supersede the Mining Law of 1872 (see below). As such, many mining activities are not subject to BLM authorization prior to implementation.

FLPMA has the potential to benefit the Lane Mountain milk-vetch and its habitat. Although the BLM identified several measures in the West Mojave Plan as their conservation strategy for the Lane Mountain milk-vetch (BLM et al. 2005, Chapter 2, p. 108), none of these measures has been implemented except the designation of the two ACECs. Given that the BLM has discretion in how this statute is carried out and measures are implemented, we continue to see continued loss and degradation of habitat for the Lane Mountain milk-vetch on lands that the BLM manages.

Amendments to CDCA Resource Management Plans Regarding Renewable Energy Development: In 2011, the BLM published its Final Programmatic Environmental Impact Statement on Wind Energy Development on BLM-Administered Lands in the Western United States. In this Final Programmatic Environmental Impact Statement (PEIS), the BLM excluded wind energy development on lands with special status designations, including ACECs (BLM 2011, Chapter 2, p. 7), and therefore the two Lane Mountain milk-vetch ACECs.

In 2012, the BLM and the Department of Energy (DOE) released their Final Solar Programmatic Environmental Impact Statement (PEIS) for Development of Solar Energy Projects in Six Southwestern States (Arizona, California, Colorado, Nevada, New Mexico, and Utah. This document evaluated actions at a landscape level that these two agencies are considering taking to facilitate further the development of utility-scale solar energy in these six states. The BLM and DOE did not identify any solar energy zones that are in or near the known

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range of the Lane Mountain milk-vetch (BLM and DOE 2012, p. ES-13). However, renewable energy development including solar can be located on private land or can be sited on BLM land if less than 20 MW in production size.

Desert Renewable Energy Conservation Plan: A State and Federal multi-agency group was formed recently to ensure implementation of California Executive Order S-14-08 and Department of Interior Secretarial Order 3285 to develop renewable energy in the California Desert. The Desert Renewable Energy Conservation Plan (DRECP) is a multi-agency plan whose goal is to streamline the permitting processes for several Federal and State environmental regulations for utility‐scale renewable energy development in the California desert. The draft DRECP is scheduled for release to the public for comment in late spring 2014. Various milestone documents (e.g., development focus areas (DFAs), Biological Goals and Objectives, Conservation Management Actions, etc.) have been developed and released that will be used to prepare the draft DRECP. Although BLM’s two Final EISs on wind and solar energy development excluded ACECs from future development, the DRECP could alter these decisions and allow development in ACECs. When the DRECP is completed, its actions will be included as an amendment to the CDCA Plan.

There are no documented occurrences of the Lane Mountain milk-vetch within any DFAs identified in the current draft DRECP alternatives. Currently there are no DFAs, existing transmission lines, or transmission line corridors identified in or close to the locations of the Lane Mountain milk-vetch plants or the Coolgardie Mesa or West Paradise Conservation Areas. Using this information, the DRECP would not likely result in focusing or encouraging renewable energy development, including additional transmission lines or pipelines, in the Coolgardie Mesa or West Paradise Conservation Areas.

As part of the DRECP process, several Conservation Management Actions are being developed for the Lane Mountain milk-vetch and other species that may be covered in the Plan. Projects (including covered activities under the DRECP and land uses under the BLM’s land use management plans) within occupied and modeled suitable habitats for the Lane Mountain milk- vetch in DFAs, several Conservation Management Actions would be implemented during siting, design, pre-construction, operations, and decommissioning. These actions include pre-project surveys; siting structures to avoid direct impacts; using existing roads and previously disturbed sites; developing and implementing worker education programs; developing and implementing approved restoration plans, weed management plans, and monitoring and adaptive management plans; and providing compensation for lost habitat (J. Fraser 2013 pers. comm.). Although currently proposed, these Conservation Management Actions may be modified, added to, or deleted during Plan development.

General Mining Law of 1872: The General Mining Law of May 10, 1872, as amended (30 U.S.C. §§ 22-54 and §§ 611-615) (Mining Law) is the major Federal law governing locatable minerals. Locatable minerals include both metallic minerals (gold, silver, lead, copper, zinc, nickel, etc.) and nonmetallic minerals (fluorspar, mica, certain limestones and gypsum, tantalum, heavy minerals in placer form, and gemstones). The Mining Law opened most BLM managed lands to citizens of the United States to explore for, discover, and purchase certain valuable mineral deposits on Federal lands that are open for mining claim location and patent (open to mineral entry). The law sets general standards and guidelines for claiming the possessory right 110

to a valuable mineral deposit discovered during exploration on BLM lands.

Because the Mining Law was primarily designed to provide access to lands for the purposes of mining, rather than to protect natural resource values, it has provided little protection to Lane Mountain milk-vetch. Casual use activities commonly occur on all BLM lands within the West Mojave planning area, as discussed in the Mining Activities section. However, the surface management regulations specify that a prior-approved plan of operations (not merely a Notice) is required for any activity greater than casual use that removes more than 1,000 tons of presumed ore for testing, disturbs more than 5 ac (2 ha) of BLM lands, or is within any lands classified as Multiple Use Classes C or L under the CDCA Plan or Areas of Critical Environmental Concern (BLM et al. 2005, Appendix P, p. 1543), such as those designated for Lane Mountain milk-vetch.

The BLM also has some discretion in interpreting the Mining Law and limiting the activities that can occur under its authority. For example, the BLM has modified its definition of casual use so it no longer includes the use of most motorized equipment (e.g., heavy machinery). The BLM also has the option of withdrawing an area from mineral entry. The BLM committed to this action for the Coolgardie and West Paradise ACECs in the 2005 West Mojave Plan; however, this process was not initiated until 2012 (see Mining Activities – Conservations Measures Implemented).

Summary

In summary, while most of these laws, regulations, and policies are not specifically directed toward protection of Lane Mountain milk-vetch, they mandate consideration, management, and protection of resources that benefit Lane Mountain milk-vetch. Additionally, these laws contribute to and provide mechanisms for agency planning and implementation directed specifically toward management of Lane Mountain milk-vetch and its habitat. Because most of these laws and regulations are national in scope and are not conditional on the listed status of Lane Mountain milk-vetch, we expect these laws and regulatory mechanisms to remain in place regardless of the legal status of that species. The Federal Endangered Species Act, along with other federal regulations, particularly FLPMA and the Sikes Act, have provided substantial conservation benefit to Lane Mountain milk-vetch. However, some of the most substantial threats to Lane Mountain milk-vetch and its habitat, especially the effects of climate change and small population size, are ones that are not addressed through existing regulatory mechanisms.

Progress Toward Recovery

Goldstone Population

The Army has established and fenced the Goldstone Conservation Area that includes habitat for approximately 90 percent of the Goldstone population. As per the INRMP, annual monitoring is conducted within long-term plots. The trend over an 8-year period indicates annual variability as well as an overall decline. Separate monitoring efforts by UCLA over a longer time period also show a declining trend.

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Montana-Brinkman Population

The Army has established and fended a limited-use zone that includes habitat for approximately 33 percent of the Paradise population. The remaining 20 percent of the population is within a designated military training zone. Per the INRMP, annual monitoring is conducted within long-term plots. The trend over an 8-year period indicates annual variability as well as an overall decline. Separate monitoring efforts by UCLA over a longer time period also show a declining trend.

Paradise Population

The Army has established and fenced the Paradise Conservation Area that includes habitat for approximately 70 percent of the Paradise population. BLM has established the West Paradise ACEC that includes habitat for approximately 10 percent of the population; it is not fenced, and management prescriptions have not been implemented. The remaining 20 percent of the population is within a designated military training zone. As per the INRMP, annual monitoring is conducted within long-term plots. The trend over an 8-year period indicates annual variability as well as an overall decline.

Coolgardie Population

The BLM has established the Coolgardie Mesa ACEC that includes habitat for approximately 95 percent of the Coolgardie population; it is not fenced, and management prescriptions have not been implemented. The Army has purchased private lands within the ACEC that will eventually be transferred to BLM. As per the INRMP, annual monitoring is conducted within long-term plots. The trend over an 8-year period indicates annual variability as well as an overall decline.

All BLM lands are subject to surface disturbance, including mining, OHV recreation, other recreational activities, and the spread of nonnative species which degrades habitat.

All Army lands, aside from those that have been designated as Conservation Areas or limited- use have been designated as medium- and high-use military training lands. Military training has not commenced and has been delayed for an unknown period of time.

All habitat where Lane Mountain milk-vetch occurs is subject to regional drought and climate change. The effects of drought on the nurse-shrubs for Lane Mountain milk-vetch has been documented recently.

Research: Substantial research into the life history of Lane Mountain milk-vetch has been sponsored by the Army. This research has elucidated the life history stages of the species and which are most vulnerable to the effects of various threats.

Combination of factors: All populations of Lane Mountain milk-vetch are subject to threats from a combination of factors, such as drought, host shrub availability, and small population size.

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U.S. Fish and Wildlife Service. 2013a. Email 2013–9–24. Bounding box of latitude and longitude for the four Lane Mountain milk-vetch populations. Ventura Fish and Wildlife Office, Ventura, California. 1 page.

U.S. Fish and Wildlife Service. 2013b. Lane Mountain milk-vetch - Distances between populations now and after implementation of Army proposed training. Email sent by Fish and Wildlife Biologist and GIS Specialist, U.S. Fish and Wildlife Service, Ventura, California on 2013-4-23. 1 page plus attachment.

U.S. Fish and Wildlife Service. 2013c. Map of conservation areas and Department of Defense land purchases. . Email sent by Fish and Wildlife Biologist and GIS Specialist, U.S. Fish and Wildlife Service, Ventura, California on 2013-6-24. 1 page plus attachment.

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U.S. Fish and Wildlife Service. 2013d. Information on mining activities on private and state lands north northeast of Barstow. Email sent by Fish and Wildlife Biologist and GIS Specialist, U.S. Fish and Wildlife Service, Ventura, California on 2013-6-18. 1 page plus attachment.

U.S. Fish and Wildlife Service. 2013e. Lane Mountain milk-vetch land ownership management and routes. Email sent by Fish and Wildlife Biologist and GIS Specialist, U.S. Fish and Wildlife Service, Ventura, California on 2013-4-18. 1 page plus attachment.

U.S. Fish and Wildlife Service. 2013f. Map of BLM road classifications, land ownership, and Lane Mountain milk-vetch (Astragalus jaegerianus) populations, San Bernardino County, California. Email sent by Fish and Wildlife Biologist and GIS Specialist, U.S. Fish and Wildlife Service, Ventura, California on 2013-3-27. 1 page.

U.S. Fish and Wildlife Service. 2013g. Questions and Answers from March 6, 2013 meeting between BLM and the Service about Lane Mountain milk-vetch Conservation Areas and land management. Email sent by Fish and Wildlife Biologist, U.S. Fish and Wildlife Service, Ventura, California on 2013-4-23 1 page plus attachment.

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Venable, D.L., and C.E. Pake. 1999. Population Ecology of Sonoran Desert Annual Plants. Pp 113142. In: Ecology of Sonoran Desert Plants and Plant Communities, Robert H. Robichaux, editor. University of Arizona Press, Tucson, Arizona.

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Walker, G.F., and A.E. Metcalf 2008a. Final Report - Analysis of Genetic Variation in the Federally Endangered Astragalus jaegerianus (Fabaceae, Papilionoideae): A Species with a Geographic Restricted Range. Presented to the U.S. Department of the Army, Ft. Irwin, National Training Center. Contract # DACW09-02-P-0060.

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Wijayratne, U.C., L.A. DeFalco, and S.J. Scoles. 2005. Effects of anthropogenic dust deposition on Lane Mountain milk-vetch (Astragalus jaegerianus). Annual report for permit TE-022630-1. U.S. Geological Survey. Sacramento, California.

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Personal Communication and Observation

Egan, T. 1996. Personal communication. Presence of mining activity recorded by BLM during one weekend at Coolgardie Mesa. Wildlife Biologist, BLM Barstow, to Botanist, U.S. Fish and Wildlife Service, Ventura, California.

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Hessing, M. 2004. Personal communication. Observations of vehicles travelling off-road at Coolgardie Mesa. Contracted Botanist for Fort Irwin, Department of the Army, to Listing and Recovery Coordinator for Plants, U.S. Fish and Wildlife Service, Ventura, California.

Livingood, J. 2013. Personal communication. Information on mining claims, mining activities, and mineral withdrawal process. Geologist, BLM Barstow during meeting with BLM Barstow personnel (Supervisory Resource Management Specialist, Geologist, Wildlife Biologist and Environmental Analysis Specialist) to Fish and Wildlife Biologist, U.S. Fish and Wildlife Service, Ventura, California on 2013-3-6; documented in email to BLM on 2013-4-23.

Rutherford, C. 1993. Personal observation. Observation and photograph of rust-colored Lane Mountain milk-vetch plants. Botanist, U.S. Fish and Wildlife Service, Ventura, California.

Rutherford, C. 2006. Personal observation. Observations and photograph of snipped branches of Astragalus jaegerianus from small mammals. Listing and Recovery Coordinator for Plants, U.S. Fish and Wildlife Service, Ventura, California.

Rutherford, C. 2006. Personal observation. Off-highway vehicle use increased in Paradise valley area between 1998 and 2006. Listing and Recovery Coordinator for Plants, U.S. Fish and Wildlife Service, Ventura, California.

Rutherford, C. Personal communication. Longevity of one Lane Mountain milk-vetch plant. Listing and Recovery Coordinator, U.S. Fish and Wildlife Service, Ventura, California. To T. Huggins,, Department of Ecology and Evolutionary Biology, University of California, Los Angeles and cited in Huggins et al. 2012b, p. 12.

Sharifi, M.R. 2004. Personal communication. Remarks made by Dr. Rasoul Sharifi during a field trip to observe Lane Mountain milk-vetch on Fort Irwin lands on February 7, 2004. Department of Ecology and Evolutionary Biology, University of California, Los Angeles. To Listing and Recovery Coordinator, U.S. Fish and Wildlife Service, Ventura, California.

Sharifi, M.R. 2006. Personal communication. Root predation by flies on Astragalus jaegerianus. Department of Ecology and Evolutionary Biology, University of California, Los Angeles. To Listing and Recovery Coordinator for Plants, U.S. Fish and Wildlife Service, Ventura, California.

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