Endangered and Threatened Wildlife and Plants; 12-Month Finding for the Lemmon Fleabane; Endangered Status for the Acuña Cactus and the Fickeisen Plains Cactus and Designation of Critical Habitat

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R2-ES-2012-0061; 4500030113]

RIN 1018-AY51

Endangered and Threatened Wildlife and Plants; 12-Month Finding for the Lemmon Fleabane; Endangered Status for the Acuña Cactus and the Fickeisen Plains Cactus and Designation of Critical Habitat

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule; 12-month finding.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), announce a 12-month finding on a petition to list as an endangered or threatened species

Erigeron lemmonii

(Lemmon fleabane). After a review of the best available scientific information we find that listing the Lemmon fleabane as an endangered or threatened species is no longer warranted, and therefore we are removing this species from the candidate list. We propose to list

Echinomastus erectocentrus

var.

acunensis

(acuña cactus) and

Pediocactus peeblesianus

var.

fickeiseniae

(Fickeisen plains cactus) as an endangered species, and we propose to designate critical habitat for both cactus species under the Endangered Species Act of 1973, as amended (Act). If finalized, the effect of these regulations would be to add acuña cactus and Fickeisen plains cactus to the List of Endangered and Threatened Plants and to designate critical habitat for these species.

DATES:

We will accept comments received or postmarked on or before December 3, 2012. Comments submitted electronically using the Federal eRulemaking Portal (see

ADDRESSES

section, below) must be received by 11:59 p.m. Eastern Time on the closing date. We must receive requests for public hearings, in writing, at the address shown in the

FOR FURTHER INFORMATION CONTACT

section by November 19, 2012.

ADDRESSES:

You may submit comments by one of the following methods:

(1)

Electronically:

Go to the Federal eRulemaking Portal:

http://www.regulations.gov

. In the Keyword box, enter Docket No. FWS-R2-ES-2012-0061, which is the docket number for this rulemaking. Then, in the Search panel on the left side of the screen, under the Document Type heading, click on the Proposed Rules link to locate this document. You may submit a comment by clicking on “Comment Now!”

(2)

By hard copy:

Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS-R2-ES-2012-0061; Division of Policy and Directives Management; U.S. Fish and Wildlife Service; 4401 N. Fairfax Drive, MS 2042-PDM; Arlington, VA 22203.

We request that you send comments only by the methods described above. We will post all comments on

http://www.regulations.gov

. This generally means that we will post any personal information you provide us (see the Information Requested section below for more information).

The coordinates or plot points or both from which the critical habitat maps are generated are included in the administrative record for this rulemaking and are available at

http://www.fws.gov/southwest/es/arizona/, http://www.regulations.gov

at Docket No. FWS-R2-ES-2012-0061, and at the Arizona Ecological Services Field Office (see

FOR FURTHER INFORMATION CONTACT

). Any additional tools or supporting information that we may develop for this rulemaking will also be available at the Fish and Wildlife Service Web site and Field Office set out above, and may also be included in the preamble and/or at

www.regulations.gov

.

FOR FURTHER INFORMATION CONTACT:

Steve Spangle, Field Supervisor, U.S. Fish and Wildlife Service, Arizona Ecological Services Field Office, 2321 W. Royal Palm Road, Suite 103, Phoenix, AZ 85021; telephone (602) 242-0210; facsimile (602) 242-2513. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule.

Under the Endangered Species Act of 1973, as amended a species may warrant protection through listing if it is an endangered or threatened species throughout all or a significant portion of its range. The Act sets forth procedures for adding species to, removing species from, or reclassifying species on the Federal Lists of Endangered and Threatened Wildlife and Plants. This document consists of a 12-month not-warranted finding and withdrawal of

Erigeron lemmonii

(Lemmon fleabane) from the candidate list, and a proposed rule to list

Echinomastus erectocentrus

var.

acunensis

(acuña cactus) and

Pediocactus peeblesianus

var.

fickeiseniae

(Fickeisen plains cactus) as endangered species and to designate critical habitat. For the remainder of this document, these species will be referred to by their common names.

The Endangered Species Act provides the basis for our action.

Under the Act, we can determine that a species is an endangered or threatened species based on any of five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence.

We have determined that the Lemmon fleabane does no longer warrant listing. Through our five factor analysis, we have determined that the previously recognized threats to the Lemmon fleabane do not rise to a level of significance such that the species is in danger of extinction now or likely to become so in the foreseeable future.

We have determined that the following are threats to the acuña cactus:

• United States—Mexico border activities including inadequacy of regulatory mechanisms, and

• Predation by native insect and small mammal predators, in combination with other natural or manmade factors, including natural environmental variability and climate conditions such as drought.

We have determined that the following are threats to the Fickeisen plains cactus:

• Livestock grazing;

• Nonnative, invasive species; and

• Predation by native small mammal predators, in combination with other natural or manmade factors, including natural environmental variability and climate conditions such as drought.

This rule also proposes designation of critical habitat for both species.

Under the Act, we must, to the maximum extent prudent and determinable, designate critical habitat for any species that is determined to be an endangered or threatened species. We are required to base the designation on the best available scientific data after taking into consideration economic and other impacts. We can exclude an area from critical habitat if the benefits of exclusion outweigh the benefits of designation, unless the exclusion will result in the extinction of the species. In total, we are proposing approximately 21,740 hectares (ha) (53,720 acres (ac)) for designation as critical habitat for

acuña cactus (Table 1) and approximately 19,901 ha (49,186 ac) for the Fickeisen plains cactus (Table 2). The proposed critical habitat for acuña cactus is located in Maricopa, Pima, and Pinal Counties, Arizona. The proposed critical habitat for the Fickeisen plains cactus is in Coconino and Mohave Counties, Arizona.

Table 1—Proposed Critical Habitat for the Acuña Cactus

Federal

Ha

(Ac)

State

Ha

(Ac)

Tribal

Ha

(Ac)

Private

Ha

(Ac)

Total

Ha

(Ac)

11,953

(29,536)

5,773

(14,266)

2,256

(5,575)

1,757

(4,342)

21,740

(53,720)

Table 2—Proposed Critical Habitat for the Fickeisen Plains Cactus

Federal

Ha

(Ac)

State

Ha

(Ac)

Tribal

Ha

(Ac)

Private

Ha

(Ac)

Total

Ha

(Ac)

6,671

(16,486)

5,617

(13,883)

3,865

(9,554)

3,748

(9,263)

19,901

(49,186)

We are preparing an economic analysis.

To ensure that we consider the economic impacts of designating critical habitat, we are preparing an economic analysis of the proposed designation.

We will seek peer review of the methods we used in our proposal.

We are seeking comments from independent specialists to ensure that our proposal is based on scientifically sound data, assumptions, and analyses.

We are seeking public comment on this proposed rule.

Anyone is welcome to comment on our proposal or provide additional information on the proposal that we can use in making a final determination on the status of these species.

Information Requested

We intend that any final action resulting from this proposed rule will be based on the best scientific and commercial data available and be as accurate and as effective as possible. Therefore, we request comments or information from other concerned governmental agencies, Native American tribes, the scientific community, industry, or any other interested parties concerning this proposed rule. We particularly seek comments concerning:

(1) These species' biology, range, and population trends, including:

(a) Habitat requirements for pollination, reproduction, and dispersal;

(b) Genetics and taxonomy;

(c) Historical and current range including distribution patterns;

(d) Historical and current population levels, and current and projected trends; and (e) Past and ongoing conservation measures for these species, their habitat or both.

(2) The factors that are the basis for making a listing determination for a species under section 4(a) of the Act (16 U.S.C. 1531

et seq.

), which are:

(a) The present or threatened destruction, modification, or curtailment of their habitat or range;

(b) Overutilization for commercial, recreational, scientific, or educational purposes;

(c) Disease or predation;

(d) The inadequacy of existing regulatory mechanisms; or

(e) Other natural or manmade factors affecting their continued existence.

(3) Biological, commercial trade, or other relevant data concerning any threats (or lack thereof) to these species and existing regulations that may be addressing those threats.

(4) Additional information concerning the historical and current status, range, distribution, and population size of these species, including the locations of any additional populations of these species.

(5) Any information on the biological or ecological requirements of the species, and ongoing conservation measures for the species and its habitat;

(6) The reasons why we should or should not designate habitat as “critical habitat” under section 4 of the Act (16 U.S.C. 1531

et seq.

), including whether there are threats to these species from human activity, the degree of which can be expected to increase due to the designation, and whether that increase in threats outweighs the benefit of designation such that the designation of critical habitat is not prudent.

(7) Specific information on:

(a) The amount and distribution of these species and their habitat;

(b) What may constitute “physical or biological features essential to the conservation of these species,” within the geographical range currently occupied by these species;

(c) Where these features are currently found;

(d) Whether any of these features may require special management considerations or protection;

(e) What areas, that were occupied at the time of listing (or are currently occupied) and that contain features essential to the conservation of these species, should be included in the designation and why;

(f) What areas not occupied at the time of listing are essential for the conservation of these species and why.

(8) Land use designations and current or planned activities in the areas occupied by these species or proposed to be designated as critical habitat, and possible impacts of these activities on these species and proposed critical habitat.

(9) Information on the projected and reasonably likely impacts of climate change on these species and proposed critical habitat.

(10) Any foreseeable economic, national security, or other relevant impacts that may result from designating any area that may be included in the final designation. We are particularly interested in any impacts on small entities, and the benefits of including or excluding areas from the proposed designation that are subject to these impacts.

(11) Whether our approach to designating critical habitat could be improved or modified in any way to provide for greater public participation and understanding, or to assist us in

accommodating public concerns and comments.

(12) The likelihood of adverse social reactions to the designation of critical habitat and how the consequences of such reactions, if likely to occur, would relate to the conservation and regulatory benefits of the proposed critical habitat designations.

(13) Information on certain populations of Fickeisen plains cactus. Specifically, there are eight populations where the Fickeisen plains cactus has been documented, but these areas have not been visited in over 18 years. Five populations are located on the Arizona Strip and are referred to as: Beanhole Well, Marble Canyon, Salaratus Draw, South Canyon, and Toquer Tank. The sixth population is located in proximity to Mays Wash that is south of the Town of Gray Mountain among Federal, State, and private lands. The last two populations are on the Navajo Nation. These eight areas are proposed as critical habitat for the Fickeisen plains cactus. We are seeking any information on specific population status of the Fickeisen plains cactus at these locations, whether these locations are currently occupied and contain the features essential to the conservation of the species, and the condition of the habitat.

Please include sufficient information with your submission (such as scientific journal articles or other publications) to allow us to verify any scientific or commercial information you include.

Please note that submissions merely stating support for or opposition to the action under consideration without providing supporting information, although noted, will not be considered in making a determination, as section 4(b)(1)(A) of the Act directs that determinations as to whether any species is an endangered or threatened species must be made “solely on the basis of the best scientific and commercial data available.”

You may submit your comments and materials concerning this proposed rule by one of the methods listed in the

ADDRESSES

section. We request that you send comments only by the methods described in the

ADDRESSES

section.

If you submit information via

http://www.regulations.gov,

your entire submission—including any personal identifying information—will be posted on the Web site. If your submission is made via a hardcopy that includes personal identifying information, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so. We will post all hardcopy submissions on

http://www.regulations.gov.

Please include sufficient information with your comments to allow us to verify any scientific or commercial information you include.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on

http://www.regulations.gov,

or by appointment, during normal business hours, at the U.S. Fish and Wildlife Service, Arizona Ecological Services Field Office (see

FOR FURTHER INFORMATION CONTACT

).

Organization of Document

The layout of this rule is as follows: The 12-month not-warranted petition finding and candidate withdrawal for the Lemmon fleabane; the proposed listing of the acuña cactus and the Fickeisen plains cactus; the proposed critical habitat for the acuña cactus and the Fickeisen plains cactus.

12-Month Petition Finding and Candidate Withdrawal for the Lemmon Fleabane

This section summarizes the status and potential threats that we evaluated in order to determine that listing Lemmon fleabane is not-warranted and to remove it from candidate status. Additional material that we relied on is available in the Species Assessment and Listing Priority Assignment Form for Lemmon fleabane. This form is available on our national endangered species Web site:

http://www.fws.gov/endangered/

(search for “Lemmon fleabane” in the Species Search box).

On July 1, 1975 (40 FR 27824), the Lemmon fleabane was included among 3,000 plant species under status review. We first identified the Lemmon fleabane as a category 1 candidate species on September 30, 1993 (58 FR 51144). Candidates are those fish, wildlife, and plants for which we have on file sufficient information on biological vulnerability and threats to support preparation of a listing proposal, but for which development of a listing regulation is precluded by other higher priority listing activities. Candidate species were assigned a relative listing priority number in accordance with listing priority guidelines published on September 21, 1983 (48 FR 43098). On the basis of immediacy and magnitude of threats, as well as taxonomic status, we assigned the Lemmon fleabane a listing priority number (LPN) of 11, which is assigned when threats are of moderate to low magnitude and non-imminent. On October 25, 1999, we changed the LPN to a 5 to reflect threats that are of high magnitude but non-imminent, based on the threat of high severity fire and drought (64 FR 57534). Later, we decided a wildfire or drought would not adversely affect the entire population; therefore, on September 12, 2006, we changed the LPN to an 8, reflecting threats that are of moderate to low magnitude and imminence (71 FR 53756), and this LPN remained in effect until the last Candidate Notice of Review in 2011 (76 FR 66370, October 26, 2011). We now find that listing this species is not-warranted, and we are withdrawing this species from candidate status because the previously recognized threats to the Lemmon fleabane do not rise to the level of significance such that the species is in danger of extinction now or likely to become so in the foreseeable future. Our rationale is explained below.

The Lemmon fleabane is a tap-rooted perennial plant of the aster family (Nesom 2006, p. 342). The Lemmon fleabane occurs in crevices and ledges, on all aspects of tall, vertical-faced, and very cuspid (pointed) Escabrosa limestone cliffs of a single canyon, Scheelite Canyon, on Fort Huachuca on Department of Defense lands, in Cochise County, Arizona (Warren

et al.

1991, p. 5; Malusa 2006, pp. 9-11). The habitat occurs over an area of approximately 50 ha (124 ac), and, as of 2006, the population is estimated to support 954 individuals (Malusa 2006, p. 9).

The primary threat previously identified for the Lemmon fleabane was high severity wildfire, a phenomenon outside of the established fire history for the forests of the Huachuca Mountains. Scheelite Canyon is a narrow, shady, bedrock-laden cold-air-drainage, with higher humidity and cooler temperatures than surrounding areas; these factors aid in limiting the spread of severe fire within the canyon (Turner and Romme 1994, p. 59; Gebow and Hessil 2006, p. 21; Werth

et al.

2011, p. 27). In addition, Scheelite Canyon is a southeast to northwest configured canyon that blocks prevailing southwesterly wind. Strong southwesterly wind was a necessary component in the unusual fire behavior documented in recent high severity fires of the Huachuca Mountains, where southwest to northeast configured canyons burned downslope and burned very hot (Leiendecker 2012, pers. comm.).

Although Scheelite Canyon currently contains a woody fuel load, fire experts believe the Lemmon fleabane itself is relatively safe from fire (Gebow and Hessil 2006, p. 51; Leiendecker 2012, pers. comm.). Recent documentation of two other rare, cliff-dwelling

Erigeron

species of the Chiricahua Mountains of

southern Arizona indicates that plants growing in cracks within the rockwall may be both resistant and resilient to high severity fire (Malusa 2012, pers. comm.). In the unlikely event of a catastrophic fire within Scheelite Canyon, it would be extremely unlikely that every Lemmon fleabane plant would be extirpated. This is because Lemmon fleabane plants occur on all aspects of rock face, on both sides of the canyon including the entrances of small tributaries, and at all elevations on the canyon wall from the canyon bottom upwards nearly 305 meters (m) (1,000 feet (ft)) to the top of the canyon walls.

In summary, there is a very small probability that Scheelite Canyon will sustain a catastrophic fire in the future due to the southeast to northwest aspect of the canyon in the landscape; its humid, shady, and cool nature; and the presence of exposed rock outcroppings throughout the canyon lending to a discontinuous fuel load. Should such a fire occur, it would threaten individual plants exposed to flame and heat (Gebow and Hessil 2006, p. 85); however, due to the plants occurring in a variety of locations within the canyon, it is unlikely that all plants would be affected.

Recreational rappelling was noted as a minor threat to the Lemmon fleabane; however, we conclude that there is a very low probability of this type of activity taking place in Scheelite Canyon because recreational rappelling is not allowed by Fort Huachuca. Further, if unauthorized rappelling were to occur, the damage to Lemmon fleabane plants would be insignificant at the population level.

In addition to fire and rappelling posing less of a threat to the Lemmon fleabane than previously believed, several conservation measures have recently occurred or are being planned. Although we did not rely on these conservation measures to make our not-warranted finding, they are underway and will benefit the Lemmon fleabane now and into the future. In 2011, the Desert Botanical Garden collected hundreds of viable Lemmon fleabane seeds for long-term storage. This collection and future-planned seed collection by the Desert Botanical Garden may help offset impacts to the species in the event of a devastating wildfire and habitat loss. In addition, the U.S. Forest Service is currently working with Fort Huachuca to reduce fire potential at a landscape level throughout the district and on Fort Huachuca itself (Leiendecker 2012, pers. comm.). Finally, Fort Huachuca and the Service are drafting a conservation agreement which, once signed, will: (a) Ensure the continued monitoring of the Lemmon fleabane population and promote adaptive management based on monitoring results; (b) continue the restrictions on recreational activities in Lemmon fleabane habitat; and (c) encourage further research into the species' life history, population biology and demographics, and distribution.

Through our five-factor analysis, we have discounted any threats to the species and conclude there are no significant threats to the Lemmon fleabane. We, therefore, conclude that the previously recognized threats to the Lemmon fleabane do not rise to a level of significance such that the species is in danger of extinction now or in the foreseeable future. Additionally, we are not aware of any other potential stressors or threats that may impact the species or its habitat by itself or in combination, including the potential environmental effects that may result from climate change. Current and planned conservation measures will also benefit the Lemmon fleabane, although we are not relying on these conservation actions as the basis for our not-warranted finding. As a result, we have removed this species from the candidate list.

Acuña Cactus and Fickeisen Plains Cactus

Previous Federal Actions

On July 1, 1975 (40 FR 27824), we published a Review of Status of Vascular Plants identifying the acuña cactus and the Fickeisen plains cactus as among 3,000 native plant taxa being reviewed for possible inclusion in the list of endangered and threatened species. On December 15, 1980, we published a Review of Plant Taxa for Listing as Endangered or Threatened Species and identified the Fickeisen plains cactus as category 1 species (45 FR 82480). Category 1 species were those taxa for which we had on file substantial information on biological vulnerability and threats to support proposing them as endangered or threatened species. The acuña cactus was not included in the 1980 notice. Both the acuña cactus and the Fickeisen plains cactus were included in the February 21, 1990, notice (55 FR 6184) as category 1 species.

In the September 30, 1993, notice (58 FR 51144) candidate species were assigned a status category indicating their status at that time. Each species was identified as increasing (I), stable (S), declining (D), or unknown (U). The 1993 notice identified the acuña cactus and the Fickeisen plains cactus as category 1-U: unknown, denoting species for which additional survey work is required to determine current trends.

We discontinued the use of a category system in the February 28, 1996, notice (61 FR 7596) and simply referred to category 1 species as candidate species. The acuña cactus and Fickeisen plains cactus were both assigned an LPN of 6, due to the high magnitude of threats which were non-imminent. We published four Candidate Notice of Reviews between 1997 and 2003, in which the acuña cactus and the Fickeisen plains cactus remained candidate species with an LPN of 6 (62 FR 49398, September 19, 1997; 64 FR 57534, October 25, 1999; 66 FR 54808, October 30, 2001; 67 FR 40657, June 13, 2002).

On October 30, 2002, we received a petition from the Center for Biological Diversity to list the acuña cactus as an endangered species under the provisions of the Act. On May 4, 2004, the Center for Biological Diversity petitioned the Service to list the acuña cactus and the Fickeisen plains cactus as an endangered species under the Act. Because these species were already candidates for listing, we did not issue findings on the petition. In the Candidate Notice of Review dated September 12, 2006 (71 FR 53756), we revised the LPN of the Fickeisen plains cactus from 6 to 3 based on direct mortality and reduced reproductive capacity resulting from off-road vehicle (ORV) use, trampling associated with livestock grazing, a continuing drought, and herbivory by rabbits and rodents. We also acknowledged that unauthorized collection of the Fickeisen plains cactus was a potential threat but we did not know at that time whether it was a continuing threat. In the notice of December 6, 2007 (72 FR 69034), we revised the LPN of the acuña cactus from 6 to 3 based on continued decline of the species caused by ongoing drought. An LPN of 3 reflects threats that are both imminent and high in magnitude, as well as the taxonomic classification as a subspecies. In plant classification generally, the use of the term variety, such as is used in the plants in this rule, is synonymous with the term subspecies. In the notice of October 26, 2011 (76 FR 66370), we retained an LPN of 3 for both species.

Background

For each of the two cactus species, we provide a description of the species, its life history, its habitat, an evaluation of listing factors for that species, and our finding for the species.

Acuña Cactus

It is our intent to discuss below only those topics directly relevant to the listing of the acuña cactus as an endangered species in this section of the proposed rule.

Species Description

The acuña cactus is a small, spherical cactus, usually single-stemmed, that can be up to 40 centimeters (cm) (16 inches (in)) tall and 9 cm (3.5 in) wide (Arizona Rare Plant Guide Committee 2001, unpaginated; Zimmerman and Parfitt 2003, pp. 194-195). The acuña cactus has 11 to 15 radial spines up to 2.5 cm (1.0 in) long and 3 to 4 mauve-colored, up-turned central spines up to 3.5 cm (1.4 in) long (Arizona Rare Plant Guide Committee 2001, unpaginated; Zimmerman and Parfitt 2003, pp. 194-195). Rose, pink, or lavender flowers 3.6 to 6 by 4 to 9 cm (1.4 to 2.3 by 1.6 to 3.5 in) are produced in March (Arizona Rare Plant Guide Committee 2001, unpaginated; Zimmerman and Parfitt 2003, pp. 194-195). The fruits are pale green, are 1.25 cm (0.5 in) long, and contain small, nearly black seeds (Felger 2000, p. 208). The fruits ripen in April (Arizona Rare Plant Guide Committee 2001, unpaginated).

Biology

The acuña cactus relies solely on the production of seeds for reproduction, with pollination highly linked to survival, as the species cannot fertilize itself. Acuña cacti are pollinated by a suite of bees from the Andrenidae, Anthophoridae, Anthophorinae, Halictidae, and Megachilidae families; however, the leafcutter bee (

Megachile palmensis

) and cactus bee (

Diadasia rinconis

) are thought to be the primary pollinators (Johnson 1992, p. 406). The maximum distance that either of these bees travel is thought to be roughly 900 m (2,953 ft) (see Critical Habitat section, below).

Although we do not know the lifespan of acuña cacti, there are individual plants that have been tracked at Organ Pipe Cactus National Monument (OPCNM) since 1977, and are still alive in 2012 (Holm 2012a, pers. comm.). The lifespan of seeds in the seedbank is unknown; however, in independent greenhouse tests of 6 and 4 year-old seed collected from two discrete populations, less than 19 percent and zero percent germination resulted, respectfully (Rutman 2007, p. 7). In tests of 1 and 2 year-old seed, germination ranged from 64 to 100 percent, and tests of seed collected 19 days previously resulted in 82 percent germination (Rutman 2007, p. 7). It is unknown if seed in its natural environment has the same short lifespan as has been demonstrated in these germination trials.

Taxonomy

This species was originally described in 1953 by W.T. Marshall as

Echinomastus acunensis

(Marshall 1953, pp. 33-34). It is known by many synonyms, including

Sclerocactus erectocentrus

var.

acunensis

(Coulter) Taylor and

Neolloydia erectocentra

(W.T. Marshall) var.

acunensis

L. Benson (Arizona Game and Fish Department (AGFD) 2004, p. 1). The Cactaceae treatment in the Flora of North America (Zimmerman and Parfitt 2003, pp. 194-195) recognizes the entity as

E. erectocentrus

var.

acunensis.

The other variety

, E. erectocentrus

var.

erectocentrus

(needle-spine cactus), is also recognized as a valid taxon in the Flora of North America. The two varieties are generally considered to be morphologically distinct and geographically isolated, but there have been questions regarding the morphology of some individuals (AGFD 2004, p. 6). To address those concerns, the Service funded a project to analyze the morphological distinctness of the two varieties, which was completed in January 2007. The results of this study suggest that there are four distinct taxonomic groups, including the separation of variety

acunensis

and variety

erectocentrus

(Baker 2007, pp. 19-21), and we concur with the study results. Therefore, the acuña cactus and the needle-spine cactus are valid and distinct taxa separated morphologically and geographically. Baker (2007, p. 20) recommended nomenclatural changes, based on the International Rules of Botanical nomenclature, but formal name changes were not proposed in his study. Again, we refer to the taxonomy determined by the Flora of North America.

Habitat

The acuña cactus occurs in valleys and on small knolls and gravel ridges of up to 30 percent slope in the Palo-Verde-Saguaro Association of the Arizona Upland subdivision of the Sonoran Desert scrub at 365 to 1,150 m (1,198 to 3,773 ft) in elevation (Phillips

et al.

1982, p. 4; Arizona Rare Plant Guide Committee 2001, unpaginated; AGFD 2011, entire). This species grows on soil overlying various bedrock types including extrusive felsic volcanic rocks of rhyolite, andesite, and tuff, and intrusive igneous rocks composed of granite, granodiorite, diorite, and Cornelia quartz monzonite; Locomotive fanglomerate (sedimentary rock consisting of heterogeneous fragments of all sizes deposited in an alluvial fan and later consolidated) is also locally present (Rutman 2007, pp. 1-2; Anderson 2012a, pers. comm.). Mineralogy of these rocks is varied, with felsic or mafic phenocrysts present, depending on bedrock type (Rutman 2007, pp. 1-2; Anderson 2012a, pers. comm.). Soil texture in these locations varies between bedrock and both coarse- and fine-textured substrates (Rutman 2007, pp. 1-2). Associated plant species include

Larrea tridentata

var.

tridentata

(creosote bush),

Olneya tesota

(ironwood),

Cercidium microphyllum

(palo verde),

Ambrosia deltoidea

(triangle-leaf bursage), and

Acacia greggii

(catclaw). The acuña cactus is often noted growing under the protective canopy of these or other associated species (Phillips

et al.

1982, p. 6; Butterwick 1982-1992, entire; Felger 2000, p. 208; Service 2011a, p. 1; Service 2011b, p. 3), which may act as nurse plants, thereby sheltering seedlings from extreme temperatures and providing some protection from mechanical disturbance (Nobel 1984, p. 316; Suzán

et al.

1996, p. 635).

Distribution and Range

The acuña cactus populations are known from Maricopa, Pima, and Pinal Counties in Arizona and from Sonora, Mexico (AGFD 2004, p. 2). In western Pima County, plants are known from the Puerto Blanco Mountains and adjacent Aguajita Wash and in the foothills of the Growler Mountains south of Dripping Spring on National Park Service (NPS) lands within OPCNM; from the Sauceda Mountains on Bureau of Land Management (BLM) lands; from Department of Defense military lands on the Barry M. Goldwater Gunnery Range (BMGR); and from private lands near Ajo. There is an unconfirmed report of acuña cactus individuals occurring on Tohono O'odham lands in the vicinity of known populations on BLM and BMGR lands; however this has not been verified (Howe 2012, pers. comm.). In Maricopa County, the acuña cactus is known from the Sand Tank Mountains on BLM lands within the Sonoran Desert National Monument. In Pinal County, plants are known from Mineral Mountain on BLM, State, and private lands. In Sonora, Mexico, the acuña cactus occurs on Reserva de la Biosfera El Pinacate y Gran Desierto de Altar (Pinacate Biosphere Reserve) and private ejido (ranch) lands. Available information indicates that the current range of this species does not differ from the historical range, with the exception that the current Ajo populations likely had been part of a larger population that

occurred before mining activity began there (Rutman 1996b, pers. comm.; Rutman 2007, p. 7). However, there are no survey records for this species in the area prior to mining activity.

Abundance and Trends

As the number of dead individuals documented within acuña cactus populations has increased greatly since study began in the 1970s (when tracking first began), it is important to track the number of healthy, unhealthy, and dead individuals. This not only allows us to document trends in total plant numbers, but can help in our understanding of the cause and extent of mortality.

Federal Land—Organ Pipe Cactus National Monument (OPCNM)

There is one large area of approximately 1,326 ha (3,277 ac) within OPCNM that contains as many as 2,000 acuña cactus individuals (Rutman 2011, pers. comm.; AGFD 2011, entire). In 1981, this population was estimated to contain 10,000 individuals (Buskirk 1981, p. 3). Within this area, two 20-by 50-m (66-by 164-ft) permanent monitoring plots were established in 1977, with the aim of investigating growth, mortality, and recruitment of this species. Between 1977 and 1981, there was 31 percent mortality in the plots (Phillips and Buskirk 1982, p. 2). Two more plots were added in 1983, and two more in 1988. From 1988 through 1991, the population was thought to be stable or increasing (Johnson

et al.

1993, p. 172). From 1993 through 2011, annual mortality was variable, but exceeded recruitment in most years (NPS 2011a, p. 2). In 2011, the total number of individuals recorded in all six plots was 39 adults and 10 juveniles, showing little change since 2010. This however represents a marked decrease since their peak in 1991, when 446 individuals were recorded in the plots, 221 of which were juveniles (Holm 2006, p. 9; NPS 2011a, entire).

In order to verify the identification and location of plants, specimens are collected, pressed, and placed on sheets that are stored in herbaria. A 1952 herbarium collection from a second location within OPCNM is evidence that a second disjunct population of the acuña cactus occurred historically within OPCNM. Current NPS staff were unaware of this herbarium collection, and the site, reported to be within 3 m (10 ft) of the U.S.-Mexico border, has not been revisited since 1952. Site visits in this area are currently considered dangerous, and therefore no efforts have been made to confirm the location of the population; we do not know if the population exists at this location.

Federal Land—Bureau of Land Management

Sauceda Mountains

—Within the Coffeepot Area of Critical Environmental Concern (ACEC), there are several small acuña cactus populations, each on less than 2 ha (5 ac) of land.

In 1982, the BLM (Phoenix District) established three 20-by 50-m (66-by 164-ft) monitoring plots on Coffeepot Mountain. These plots were visited, and data were collected periodically between 1982 and 1992. In 1982, 157 living and 3 dead plants were found within plots. Over the years of study, many new recruits were found; however, there was also ongoing mortality with newly dead individuals documented each year. A census of individuals from both within and nearby the plots in 1987 found 310 living and 332 dead plants (Rutman

et al.

1987, p. 2). BLM staff reported a precipitous decline of this population in 1989 (Johnson 1989, p. 1). By the last monitoring visit to the plots in 1992, 150 plants were recorded dead, 22 plants were recorded missing and presumed dead, and 150 plants remained that were either healthy or in some stage of decline (Butterwick 1982-1992, entire). A note to the files in 1991 stated that many individual plants were missing, dead, or dying, and that there appeared to be little regeneration in this population (BLM 1991, p. 1). The plots have not been formally measured since 1992, but the BLM has visited this site 21 times since then to assess general health and threats to the population. Field notes by the BLM botanist in 2007 mentioned that the number of living individuals in and near these plots had been reduced by half since the 2006 site visit (Anderson 2011, p. 2). Because no population estimates were made during either year, it is difficult to know how many plants survive in and around these plots. Field notes do indicate that few juveniles were seen in 2008, and no juveniles were seen in 2009; no mention of juveniles was made in 2010 or 2011 (Anderson 2011, p. 2).

In 2006, a second population, estimated to be between 50 and 100 individuals, was located 1.2 kilometers (km) (0.75 miles (mi)) northwest of the Coffeepot Mountain monitoring plots in Ryans Canyon (Rutman 2006, p. 2). Rutman (2006, entire) did not mention size class or health of this population. This site has not been revisited.

A third population was discovered in 2006, 1.4 km (0.87 mi) to the northeast of the Coffeepot Mountain monitoring plots. Approximately 30 acuña cacti were noted there at the time; 25 percent mortality was reported one year later (Anderson 2011, p. 1). An October 2011 site visit by Service and BLM botanists revealed 23 adult and 2 juvenile living and 15 dead plants at this location (Service 2011a, p. 3). A fourth population was discovered by the BLM in March 2011, in a location near the third population; 10 plants were noted. No indications were given as to the age class structure or health of this population (Anderson 2011, entire).

At a site BLM calls Little Ajo Mountains, southeast of the New Cornelia Mine on less than 0.4 ha (1 ac), the population has fluctuated from 5 plants in 1997, to 7 plants in 2001, to 7 plants in 2006, to 11 plants in 2007, to 7 plants in 2008, and finally to 12 plants (including 5 very small plants) in 2011 (Rutman 2006, p. 2; Anderson 2011, entire; Service 2011a, p. 1).

Sonoran Desert National Monument

—In 2006, approximately 200 individuals were reported from the Sand Tank Mountains in an area less than 25 ha (61.8 ac) in size. In 2007, the site was revisited, and four groups of individuals accounting for 125 of the approximately 200 individuals were mapped (Anderson 2012b, pers. comm.; Anderson 2011, p. 2). No indications were given as to the age class, structure, or health of this population (Anderson 2011, entire).

Mineral Mountain

—There are 3 individual acuña cacti growing on BLM land adjacent to 30 living plants and 22 dead plants on State lands. This population is discussed collectively below under State lands.

Federal Land—Barry M. Goldwater Gunnery Range

In 1997, a single adult individual was reported from just north and outside of the populations in the Coffeepot ACEC (Geraghty

et al.

1997, p. 5) within Department of Defense (DOD) managed lands on the Barry M. Goldwater Gunnery Range (BMGR); this site has not been revisited.

State Land

Mineral Mountain

—Plants were collected by Hart in 1992, from the population straddling BLM and State land east of Florence (University of Arizona Herbarium 2011, entire). There were no details of the number of individuals seen, just a map with three locations. In the 1990s, the BLM revisited this site and estimated 100 individuals scattered across 3 ridgelines (Service 2008a, p. 1). In 2008, the Service and BLM searched this area. The Service and BLM found fewer than 20 living and many dead plants; no young plants were seen. In 2011, the

Service and BLM botanists revisited the location and found 30 living and 22 dead plants scattered across 4 adjacent ridgelines on less than 5 ha (12.4 ac) of land; no juveniles were found (Service 2011b, p. 1).

Ninety-Six Hills

—This population is in the vicinity of Florence on less than 1 ha (2.47 ac) of land. Parfit (1977, p. 1) noted that plants here were common, but very localized. Many plants of various ages and sizes were noted, as well as many dead plants. Engard (1977, p. 1) noted many seedlings and mature plants and also that the plants were abundant locally. Rutman and Krausman (1988, p. 1) found 29 live plants and 6 dead plants in a 2-hour survey in the same general area. Breslin (2008, pp. 3-5) reported that in over 60 hours of survey effort in the area he had located 45 plants, 1 seedling, and 17 dead plants. On March 20, 2008, the Service plant ecologist found 11 live plants and 10 dead plants in a 3-hour survey. In the same general area, C. Butterworth (2008, pers. comm.) found 32 live plants, of various sizes, except seedlings. He noted that seedlings were very noticeably absent. A 2011 2-hour survey by three Service and BLM botanists revealed no living and two dead adults in this same general area (Service 2011b, p. 3). Because this population was not mapped with Geographic Information Systems, it is impossible to know if survey efforts in 1977, 1988, 2008, and 2011 were all conducted in the exact same location within this general area. Therefore, it is not possible to conclude that this population has been extirpated.

Private Land

Ajo Area

—The combined area of these multiple sites is less than 0.4 ha (1 ac) (Rutman 2007, p. 1).

An isolated population near Darby Wells was first reported by Heil and Melton (1994, p. 14). Fewer than 10 plants were found at this site in 2007 (Rutman 2007, p. 4). There is no record if juveniles were among the plants found. The site has not been revisited.

On Indian Village Hill, there were 102 plants in 1996, when the population was first recorded (Rutman 1996b, pers. comm.). In 2006, 30 living and 33 dead plants were found; in 2007, a quick census noted fewer than 40 plants found (Rutman 2006, p. 1; Rutman 2007, p. 4). There is no record if juveniles were among the plants found in either year. In 2011, eight living and seven dead plants were recorded; no juveniles were found (Service 2011a, p. 1).

There were 16 live and 19 dead plants on Weather Tower Hill in 2006 (Rutman 2006, p. 1). There is no record if juveniles were among the plants found. The site has not been revisited.

Florence Area

—Roadside populations occur on less than 0.4 ha (1 ac) collectively; any additional populations that may be present on private land occur on an unknown quantity of land.

Roadside Population One

—The 2011 site visit revealed 9 living and 2 dead individuals; no juveniles were found, though all 9 were young healthy individuals (Service 2011b, p. 2)

Roadside Population Two

—The 2011 site visit revealed 2 living and 2 dead individuals; no juveniles were found (Service 2011b, p. 2)

There may be other locations on private lands unknown to Service or BLM botanists.

Sonora, Mexico

Felger (2000, p. 208) noted the occurrence of the acuña cactus between 3 and 18 km (2 and 11 mi) southwest of Sonoyta; no population estimates were made. Surveys of 7 groups of plants in this area from 2009 through 2010 revealed 659 living and 942 dead plants growing on approximately 1,700 ha (4,200 ac) (Pate 2011, pers. comm.; Pate 2011, map 1 and map 2). Pate (2012a, pers. comm.) noted seeing a few small seedlings among these plants.

Summary

Presented below is the total estimate of living, dead, and juvenile acuña cactus plants in populations visited over multiple years, including census results from 2011 and from previous years if sites have not been revisited or population estimates not updated. Notable trends are the large amount of mortality within the populations that have been visited more than once and the low numbers of juvenile plants in the populations.

• NPS—2,000 plants, or 58.9 percent of known individuals; estimated in 2011 by NPS staff. This population estimate is down from 10,000 individuals estimated at this location in 1981. Within the OPCNM plots, the number of recorded individuals peaked in 1991, with 446 plants found. In 2011, 49 total individuals including 10 juveniles were noted within these plots.

• Sonora, Mexico—659 plants or 19.4 percent of known individuals; estimated from 2009 to 2010 surveys. Nine hundred and forty-two dead individuals were also recorded during this survey period. There are no previous estimates from this population. A few juvenile plants were noted during the 2009 to 2010 survey period.

• BLM—655 plants, or 19.3 percent of known individuals; estimated from 2011 and other recent surveys. At Coffeepot mountain within the largest BLM population, 310 living and 332 dead individuals were recorded in 1987. This population was reduced to 150 individuals by 1992, and was reduced to approximately 75 individuals by 2006. No juveniles were noted since 2008, when a few were seen.

• Private Land—48 plants (37 near Ajo and 11 near Florence), or 1.4 percent of known individuals; estimated from 2011 and other recent surveys. A single population that was revisited on several occasions showed a total population of 102 individuals in 1996; in 2006, 30 living and 33 dead plants were found. In 2011, just 8 adult plants and no juveniles were recorded from this population.

• State Land—32 plants, or 0.9 percent of known individuals; estimated from 2011 surveys. At one location in the 1990s, the population was estimated to be 100 individuals; in 2008, only 20 living and many dead plants were found with no juveniles seen. In 2011, 30 living plants were recorded, including a new subpopulation previously not recorded. No juvenile plants were located in 2011. At a second location, in 1977, plants were considered common but localized, and the site supported many plants of various ages and sizes. Surveys of this area in 2008 resulted in the location of 45 adult plants with no juveniles found. In 2011, no living plants and two carcasses were located in this same area.

• Military BMGR—1 plant, or less than 0.1 percent of known individuals in 1997; the site has not been revisited.

Summary of Factors Affecting the Acuña Cactus

Section 4 of the Act (16 U.S.C. 1533), and its implementing regulations at 50 CFR part 424, set forth the procedures for adding species to the Federal Lists of Endangered and Threatened Wildlife and Plants. Under section 4(a)(1) of the Act, we may list a species based on any of the following five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; and (E) other natural or manmade factors affecting its continued existence. Listing actions may be warranted based on any of the above threat factors, singly or in combination. Each of these factors is discussed below.

Factor A. The Present or Threatened Destruction, Modification, or Curtailment of Its Habitat or Range

Based on the habitat characteristics described above, potential factors that may affect the habitat or range of the acuña cactus are: (1) Urban development and site degradation; (2) livestock grazing; (3) border activities; (4) nonnative, invasive plant species; (5) mining; and (6) drought and climate change.

Urban Development and Site Degradation

The immediate threats from urban development include the direct loss of individuals and habitat. Indirect impacts of urban development include fragmentation of acuña cactus and associated pollinator populations, which can reduce genetic vigor of the cactus and result in degradation and fragmentation of habitat adjacent to development. When development occurs, there is also an increased use of habitat for recreational activity, which may also deplete habitat and result in mortality of individuals. The acuña cactus populations in OPCNM and the Sonoran Desert National Monument are protected from the immediate threats associated with urban development due to their National Monument status. National Monuments are lands set aside and managed to protect the natural and cultural resources within; development is minimal, though some site degradation may still occur.

To meet the country's energy demands, there has been a recent emphasis by the Federal Government to use BLM lands for development of renewable energy. Currently, there are no planned solar or wind energy projects on or near populations of the acuña cactus in the Sauceda, Sand Tank, or Mineral Mountains (Werner 2011, pers. comm.). In addition, most populations on BLM lands are remotely located and relatively inaccessible; therefore, we do not anticipate development in these areas.

As Arizona's population is expected to continue to grow in the future, both Pinal County and the State Land Department are promoting urban development in the vicinity of Florence (Pinal County 2009, pp. 4, 60, 94; Guthrie

et al.

2011, p. 1). When the housing market rebounds, it is likely that additional State lands in this area will be sold for urban development (Pinal County 2009, p. 42; Guthrie

et al.

2011, p. 2). In the vicinity of Florence, there are no current plans for development of State lands known to support acuña cacti. Private lands near Florence containing acuña cacti populations have been for sale as subdivided 16.2-ha (40-ac) parcels for many years. With the recent economic downturn, it is unlikely this land will be sold in the near future. The only known private land populations where access is readily available are at 3 sites near Ajo, totaling less than 0.4 ha (1 ac) and supporting fewer than 40 individuals in total (Rutman 2006, p. 1; Rutman 2007, pp. 1, 4; Service 2011a, p. 1). In most of the privately owned locations, the sites are littered with broken glass, bottles, and trash; however, plants appear little impacted by this habitat degradation (Service 2011a, p. 1; Service 2011b, p. 2).

Indirect urbanization effects to the areas that support the acuña cactus include ORV activity, which has been reported on BLM lands near both Ajo and Florence. These reports, however, showed no impact on the acuña cactus populations in 1994 (Heil and Melton 1994, pp. 15-16), although habitat degradation and direct loss of individuals is possible from this activity. In 1988, the BLM closed the Coffeepot ACEC to recreational ORV use (BLM 2011, p. 194) and, in 1990, prohibited ORV use outside of designated trails within the Sonoran Desert National Monument (BLM 2011, p. 181). In 2011, the BLM Lower Sonoran Field Office released a Draft Resource Management Plan and Environmental Impact Statement (Draft RMP/EIS) for review (BLM 2011, entire). This document supports the continued prohibition of ORVs outside of designated trails within the Sonoran Desert National Monument (BLM 2011, p. 181). Within the Coffeepot ACEC, alternatives for motorized travel range from no use to limited use on existing routes, but all alternatives restrict travel off of existing routes, thereby reducing the potential for impacts to the acuña cactus (BLM 2011, pp. 181, 185-188). Once finalized, the new RMP/EIS for the Lower Sonoran and the Sonoran Desert National Monument will remain in effect for the next 15 to 20 years (Foreman 2011, pers. comm.). The impacts of ORV activity on State or private lands are unknown; for ORV activity within the border region, see the discussion below of border activities.

In Sonora, Mexico, scattered populations of the acuña cactus occur within 10 km (6.2 mi) of the town of Sonoyta. Although the area is reported to be little-used and unoccupied except by drug and human smugglers (Pate 2011, pers. comm.), in recent decades and as a result of human demand, the Sonoyta region has been heavily impacted by

Olneya tesota

(ironwood) and

Prosopis velutina

(mesquite) woodcutting for coal production, brick foundries, and tourist crafts, and the lands' subsequent conversion to exotic grasslands for cattle grazing (Suzán

et al.

1997, pp. 950, 955). This activity has affected more than 193,000 ha (478,000 ac) of lands in the Sonoyta region (Nabhan and Suzán 1994, p. 64). In a study of ironwood

extraction in northern Mexico, the Sonoyta study sites exhibited the highest number of damaged and dead trees, and had the lowest associated plant diversity (Suzán

et al.

1996, p. 642). It is likely that habitat parameters for the acuña cactus

populations in Sonora are impacted by this activity, particularly because ironwood is considered a dominant associate of the acuña cactus (Phillips

et al.

1982, p. 5) and may serve as a nurse plant for a variety of cacti (Suzán

et al.

1996, p. 635).

In addition, the actions of harvesting, burning, loading, and transporting wood and charcoal can result in running over individual acuña cactus and causing injury or mortality of plants, if such actions occur in areas supporting the acuña cactus. Also, human population growth and development in the border region between the United States and Mexico has risen in recent decades (Brown and Caldwell 2008, pp. 1-6); it is reasonable to conclude that the direct and indirect effects of urbanization are likely to increase threats to the acuña cactus populations in this region. The populations are currently split by a major highway, Interstate 8, and a power transmission line; many plants occur within 200 m (660 ft) of these corridors (Pate 2011, map 1 and map 2).

In summary, the direct and indirect effects of urbanization are threats to a portion of the known populations of the acuña cactus. However, these effects are currently limited to the acuña cactus populations in the vicinity of Ajo and Florence in the United States and in the immediate border region of Sonora, Mexico. These areas collectively make up less than 21 percent of known living acuña cactus individuals across the range of the acuña cactus. The majority of the range in the United States is protected from urban development because populations are on Federal lands, where little or no development will take place. In addition, most populations of the acuña cactus are relatively remote or otherwise protected from the effects of urbanization. We conclude that urban development and site degradation is not currently a threat to any entire population of the acuña cactus. As a result, based on our review of the available information, we conclude that the direct and indirect

effects associated with urbanization are not threats to the acuña cactus and its habitat.

Livestock Grazing

In general, grazing practices can change vegetation composition and abundance and cause soil erosion and compaction, reduced water infiltration rates, and increased runoff (Klemmedson 1956, p. 137; Ellison 1960, p. 24; Arndt 1966, p. 170; Gifford and Hawkins 1978, p. 305; Waser and Price 1981, p. 407; Robinson and Bolen 1989, p. 186; Holechek

et al.

1998, pp. 191-195, 216; and Loftin

et al.

2000, pp. 57-58). These anticipated effects leave less water available for plant production (Dadkhah and Gifford 1980, p. 979). In addition, livestock can step on or knock over individual acuña cactus. Although other species of cacti may be good survival forage for livestock (Vega- Villasante

et al.

2002, p. 499), herbivory of the acuña cactus has not been reported. Livestock grazing levels and habitat condition vary greatly between populations due to varied land ownership and management. A discussion of populations arranged by land management agency follows.

National Park Service

—Beginning in the early 1900s and continuing through the 1970s, lands within OPCNM were grazed heavily, with as many as 3,000 head of cattle and hundreds of burros present at a time when carrying capacity was estimated to be 314 cattle per year (Rutman 1997, p. 364; NPS 2011b, entire). Grazing by domestic animals was halted per NPS policy and has not occurred within OPCNM since 1976 (NPS 1997, p. 33). Lands here continue to recover slowly after loss of soils and vegetation and may take many decades or centuries to recover fully (NPS 2001, pp. 27, 124). Currently, OPCNM supports the largest population of the acuña cactus (59 percent of known living acuña cactus individuals), and we are not aware of historical effects to the population as a result of past livestock grazing.

Bureau of Land Management

—All four populations of the acuña cactus on BLM lands in the Sauceda Mountains have been managed since 1988 in the Coffeepot ACEC, which attempts to apply grazing management practices to ensure perpetuation of botanical diversity within the area and prohibits the development of livestock facilities that would serve to increase livestock use within the area (BLM 2011, p. 141). Collectively these four populations make up 13.1 percent of known living acuña cactus individuals. In 1987, when speaking of the then proposed Coffeepot ACEC, Olwell (1987, p. 1) noted relatively pristine conditions with no immediate threat to the acuña cactus plants. At that time, however, the population of acuña cactus within the Coffeepot ACEC in the vicinity of permanent monitoring plots was reported to have substantial animal activity from cattle, javelina, and jackrabbits, with browsing, grazing, and soil disturbance noted (Rutman

et al.

1987, p. 2). Anderson (2011, entire) noted no habitat impacts from grazing in this population during yearly visits from 1994-2011. This population is the farthest population from a single cattle tank (see below) within the ACEC, and therefore is less subjected to livestock pressure.

In 1970, a cattle tank named Conley Reservoir was established within the Coffeepot ACEC boundary prior to the ACEC designation and remains today (Foreman 2012, pers. comm.). A population of acuña cactus very near this tank was visited by the BLM botanist in 2010, who found abundant prickly pear (

Opuntia

spp.), which are known to increase with disturbance and are often cited as an indicator of poor range condition (Anderson 2011, p. 2; Johnson 2000, entire). A site visit in 2011 by Service and BLM botanists found habitat impacts such as soil disturbance from both cattle and feral burros; however, no acuña cactus plants appeared to be directly impacted by these animals (Service 2011a, p. 3). Feral burros also impact vegetation on neighboring military lands (see

Department of Defense

section below).

The new BLM Draft RMP/EIS has implications for future livestock management within the Coffeepot ACEC and the Sonoran Desert National Monument (BLM 2011, entire). According to this document, under Alternative A (the no action alternative), livestock grazing within the ACEC would not change from the current regimes with no livestock facility development permitted (BLM 2011, pp. 32, 141). Under Alternative B, livestock grazing only in times of suitable forage production (ephemeral) would continue to be considered, but perennial stocking rates would be reduced by approximately 40 percent, and no livestock facilities would be developed that would increase livestock use within the area (BLM 2011, pp. 33, 196). Under Alternative C, grazing allotments designated as perennial/ephemeral would be reclassified as perennial only, with no supplemental ephemeral grazing applications considered (BLM 2011, p. 34). Under Alternative D, all allotments currently open to grazing would become unavailable as permits expire (BLM 2011, p. 35). Under Alternative E, the BLM's preferred alternative, current grazing levels and timing would remain the same, but livestock facilities could be developed with the aim of improving natural resource conditions through greater distribution of livestock (BLM 2011, p. 171). It is unclear if additional tanks would, as is implied, relieve pressure on the acuña cactus populations; it is also unclear if this would increase the overall number of cattle (or burros) in the area or the amount of land impacted, thus potentially impacting more acuña cactus populations. Whichever alternative is ultimately chosen, the finalized version of this management plan will remain in effect for 15 to 20 years after signing later in 2012 (Foreman 2011, pers. comm.).

In 2001, Presidential Proclamation 7397 (Clinton 2001, entire) created the Sonoran Desert National Monument; one population of acuña cactus containing 5.9 percent of known living acuña cacti occur in the Sand Tank Mountains. This area was designated for military purposes in 1941, and has had no livestock grazing for over 60 years (Clinton 2001, p. 2). During a site visit in 2006, no habitat impacts from livestock were reported from this location (Anderson 2011, p. 2). The current livestock management regime of no livestock being permitted within the Sonoran Desert National Monument Sand Tank Mountains acuña cactus population will be maintained for at least the next 15 to 20 years (BLM 2011, pp. 36-40; Foreman 2011, pers. comm.).

Department of Defense

—A single acuña cactus plant was found on BMGR approximately 1 km (0.62 m) to the north of a known population within the BLM Coffeepot ACEC (Geraghty

et al.

1997, p. 5). Livestock grazing is not authorized on the BMGR, though some trespass cattle do occur (Whittle 2012, pers. comm.). Feral burros on BMGR are a concern, however, and BMGR managers plan to implement a burro trapping program in the spring of 2012, in an attempt to reduce damage to vegetation (Whittle 2012, pers. comm.).

Arizona State Trust Lands (State land)

—Populations of acuña cactus on State land in the Mineral Mountains are subject to grazing; two land sections containing this species are collectively part of a larger 6,118-ha (15,118-ac) grazing lease with a total carrying capacity of 118 animal units (Sommers 2012, pers. comm.). Three individual acuña cacti from this group of populations overlap onto adjacent BLM land. This BLM land, which is not fenced from adjacent State land, has a total permitted number of cattle of 357 year long, though the lessee did not run

the full amount of animals in 2011 (Tersey 2012, pers. comm.). During a 2011 site visit, the habitat appeared unaltered by livestock, and no cattle were seen (Service 2011b, p. 1).

Three additional land sections near Box O Wash containing this species are collectively part of a lease of 12,369 ha (30,565 ac) with a total carrying capacity of 236 animal units (Sommers 2012, pers. comm.). Both leases incorporate State and BLM lands, although in this area the species has been found on State lands and not the associated BLM lands. No livestock were seen during the November 2011 site visit to this population (Service 2011b, p. 3). Only two dead individual acuña cacti were found, and neither appeared to have been knocked over by cattle (Service 2011b, p. 3). In the past, Rutman and Krausman (1988, p. 1) recommended that this State land habitat could benefit from improved livestock management, as cattle trails there were numerous during a 1988 site visit. In a 2008 site visit, it was noted that quite a few of the dead acuña cactus plants may have been knocked over by livestock (Service 2008b, p. 1). It is unknown what the grazing lease or animal units were for this period of time. In 2011, several individuals were noted to have grown additional arms following the loss of the growing tip (Service 2011b, pp. 3-4). This was possibly due to mechanical damage caused by cattle, a beneficial adaptation to disturbance noted previously by Phillips

et al.

(1982, p. 6). The populations on State land represent just 0.9 percent of known living acuña cactus individuals. Although livestock grazing on State lands may benefit from improved management, the impacts to the acuña cacti are small.

Private

—Populations of the acuña cactus on private lands near the town of Ajo were noted to occur in degraded habitat with low species richness; these sites were suspected to have had a grazing history of severe use (Rutman 1995, p. 1). Those acuña cacti on private lands near Florence are in an unknown condition, as they are not typically visited by Service staff. Two roadside populations visited in 2011 had four dead plants and 13 healthy plants collectively; all dead plants seemed to have died from drought or insect attack, although one population did contain evidence (feces) of cattle use (Service 2011b, p. 2). Private lands account for just 1.4 percent of known living acuña cactus individuals.

Mexico

—In Mexico, researchers report livestock grazing in parts of the Sonora range (Stoleson

et al.

2005, p. 60), but mostly the habitat remains little-used and unoccupied land (Pate 2011, pers. comm.). Sonora maintains 19.4 percent of the known acuña cactus individuals across the range; their recent decline, as evidenced by nearly 1,000 dead plants counted in 2010, has not been attributed to livestock.

In summary, 64.9 percent of acuña cactus individuals occur within lands protected from cattle grazing either by NPS or BLM National Monument status. In areas occupied by the acuña cactus where livestock grazing does occur, impacts from livestock do not appear to be a consistent or significant threat to populations. Based on our review of the available information, we conclude that, although there is evidence that grazing impacts to the acuña cactus do occur, we do not believe that these effects occur to such an extent that livestock grazing is a threat to the acuña cactus and its habitat.

Border Activities

Over the past decade or more, tens of thousands of people illegally attempt crossings of the U.S.-Mexico border into Arizona annually (cross-border violators) (Service 2011c, p. 14). As a result of increased U.S. Customs and Border Protection (CBP) in the Douglas, Arizona, area, and in San Diego and southeastern California, cross-border violator traffic has shifted into remote desert areas such as OPCNM (Service 2011c, p. 14). For example, in 2001, an estimated 150,000 people entered OPCNM illegally from Mexico (Service 2011c, p. 14). With the increase in technology, border fencing, and manpower between 2001 and 2012, these numbers are down considerably, with 6,218 arrests of cross-border violators from OPCNM in the year 2011 (Oliver 2012, pers. comm.). Although the number of arrests does not represent all those who attempted to enter OPCNM illegally, this number is suspected to be considerably less than reported in 2001. Despite the fact that these numbers are down due to enforcement and deterrence efforts by the CBP, the thousands of people crossing through the border area illegally still represent a substantial impact to the resource.

More than 78 percent of the known living acuña cactus individuals occur within 16.5 km (10.25 mi) of the border in either OPCNM or Sonora, Mexico. Cross-border violators, CBP, and NPS Law Enforcement (LE) activity in this area may degrade acuña cactus habitat by creating new roads and trails, disturbing vegetation and soils, and moving exotic plant seeds or plant parts, leading to their spread into unoccupied areas (Duncan

et al.

2010, p. 124). At OPCNM, the acuña cactus occurs in an area that is closed to visitors due to dangers of drug and human smuggling; in addition, for many years, OPCNM natural resource staff have not been allowed to access the area without LE personnel accompanying them. Significant impacts may occur when travel moves off existing roads causing vegetation destruction, soil compaction (Duncan

et al.

2010 p. 125), and, potentially, direct mortality of the acuña cactus by running over individuals, although no direct impacts to acuña cactus have been observed. Staff at OPCNM note that roughly 2 years ago, two vehicle tracks and associated articles of clothing from cross-border violators were found within one of the six 20 by 50 m (66 by 164 ft) acuña cactus long-term monitoring plots (Holm 2012a, pers. comm.). Although no individual plants were reported to have been run over in this instance, the occurrence of the activity within this proximity to acuña cactus individuals supports our conclusion that impacts from cross-border violators and border enforcement may negatively impact the species and could be a threat.

In 2006, a vehicle border fence was completed in OPCNM. This fence has significantly reduced vehicular traffic from illegal entrants. The Biological Opinion for the Ajo Forward Operating Base Expansion reported personal observations by NPS and Service employees that the number of off-road tracks and new roads continues to increase (Service 2011c, p. 19). These new off-road tracks and roads are believed to be the result of CBP response by vehicle, horseback, and foot to cross-border violators, who are travelling primarily on foot (Service 2011c, p. 19). By 2011, OPCNM personnel had mapped thousands of miles of unauthorized off-road impacts from cross-border violators, CBP, and LE activities (Service 2011c, p. 18). Staff at OPCNM has been compiling data on off-road traffic and mapping unauthorized roads on OPCNM for a report. Prior to finalizing the determination on listing the acuña cactus, this report will have been completed and will be considered in the final determination. Although most of the unauthorized roads were created prior to construction of vehicle and pedestrian fences along the U.S.—Mexico international border, it is not known if the additional roads were created after the construction of the border fences. In 2011, NPS staff noted no new heavily utilized routes due to off-road travel by vehicles, but staff did state that single vehicles drive across habitat, and individual acuña cactus plants may be driven over. There is no

evidence that acuña cacti have been harmed, but damage to larger plants has been documented due to similar activity (Rutman 2011, pers. comm.). In cooperation with Service staff, CBP has begun efforts to educate Border Patrol agents on the locations and appearance of acuña cactus so that the areas that support the plant can be avoided to the maximum extent possible. Designated critical habitat in OPCNM will be marked on road atlases being prepared by OPCNM staff and provided to the agents patrolling in the OPCNM area.

A system of sensors and communication towers is currently in place and is being expanded within the border region; this technology improves deterrence, detection, and apprehension of cross-border violators entering or attempting to enter the United States illegally (Service 2009, p. 5). It is expected that with increased communication and sensor tower technology, there will be a reduction in the need for CBP agents to patrol the area, thus reducing circumstances requiring vehicles to drive off of authorized roads (Service 2009, p. 16). CBP agents on foot or on horseback may conduct off-road pursuit of suspected cross-border violators at any time, including in areas designated or recommended as wilderness (Service 2009, p. 17). However, where there are exigent or emergency circumstances, CBP agents may conduct motorized off-road pursuit of cross-border violators, including in areas designated or recommended as wilderness. Where such motorized pursuits are necessary, CBP has committed to using the least intrusive or least damaging vehicle readily available, without compromising officer or agency safety.

There are no existing or proposed communication towers near any acuña cactus populations within OPCNM; however, human traffic patterns have changed since the installation of towers in and near OPCNM. This change of pattern has created a larger impact footprint due to traffic moving farther from towers. In addition, communication and sensor towers and associated tactical infrastructure require maintenance and repair. Species proposed for listing, such as the acuña cactus, could be directly affected by repair and maintenance of this infrastructure if maintenance vehicles traveled off of approved access routes. However, CBP has committed to use only approved access routes for these maintenance activities. Therefore, these effects would be negligible for acuña cactus. In addition, if these maintenance and repair activities occur in undisturbed areas in the habitat of listed plant species, a survey must be conducted and a sufficient buffer created to protect any plants found (HDR 2012, pp. 4-3).

Illegal drug and human smuggling also adversely affects the area of the Coffeepot ACEC, but the area is less impacted than other border areas (BLM 2011, p. 344). This is likely the case with the other populations on private and BLM lands near Ajo and Florence. Within BMGR, cross-border violators and associated activities represent a significant threat to natural and cultural resources within the BMGR, including having widespread and adverse effects on soil and hydrology (U.S. Departments of the Air Force and Navy 2007, pp. 3-11). We are aware of no instances of illegal activity or law enforcement activity impacting the populations near Florence. The Service (2008b, p. 1) noted that little to no human activity, including ORV use, was observed during a 2008 site visit to these populations.

The acuña cactus populations across the border from OPCNM, in Mexico, occur on land that is little-used, unoccupied, and subject to heavy traffic by drug and human smugglers (Pate 2011, pers. comm.). This area was reported to be not very safe, and warnings were given to Service personnel not to travel to this location alone (Larios 2011, pers. comm.). In 1993, the Mexican government established Pinacate Biosphere Reserve, a 7.7-million ha (1.9-million-ac) reserve for the region's flora, fauna, geology, and archeology preservation. A portion of the acuña cactus individuals in Sonora occur within the Pinacate Biosphere Reserve. It is unknown what, if any, protection this designation provides the acuña cactus.

In summary, the two areas containing the largest number of living acuña cactus (78 percent of the known living acuña cactus individuals) occur along the U.S.-Mexico border (in OPCNM and Sonora, Mexico). Within populations, acuña cacti are typically spaced within 3 m (9.8 ft) of each other, and thus vehicle traffic through any population could potentially impact many individuals. This area is heavily impacted by cross-border violators, CBP, and LE activity, as evidenced by the tremendous increase in illegal roads and trails documented by agencies along the border. To date, no individual acuña cactus plants are reported to have been lost to these activities; however reporting from this area is inconsistent. With anticipated continued border activity in the area, it remains possible that acuña cactus individuals and their habitat will be impacted. These impacts include: creation of new roads and trails; disturbance of associated vegetation including nurse plants and microclimates; compaction or erosion of soils; movement of nonnative, invasive plant seeds and plant parts; and the potential to cause direct mortality to individuals by running over plants with vehicles. Therefore, based on our review of the available information, we conclude that cross-border violators, CBP, and LE off-road activities are a threat to the acuña cactus and its habitat.

Nonnative, Invasive Plant Species

Throughout the Sonoran Desert ecosystem, invasions of the introduced

Pennisetum ciliare

(buffelgrass),

Bromus rubens

(red brome),

Eragrostis lehmanniana

(Lehmann lovegrass),

Schismus barbatus

(Mediterranean grass), and

Pennisetum setaceum

(crimson fountaingrass) have altered nutrient regimes; species composition and structure; and fire frequency, duration, intensity, and magnitude (Brooks and Pyke 2001, p. 5). Although most of these species were intentionally introduced as forage for livestock, as erosion control, or as ornamentals, each is now considered invasive and a threat to this ecosystem (Búrquez-Montijo

et al.

2002, entire). Species such as buffelgrass are expected to increase their range even with continued and predicted drought events (Ward

et al.

2006, p. 724). It is generally thought that invasion by exotic annual grasses will continue unchecked in the Sonoran Desert ecosystem in the future, reducing native biodiversity through direct competition and alteration of nutrient and disturbance regimes (Franklin and Molina-Freaner 2010, p. 1671).

Herbarium sheets contain labels that give information regarding where a specimen was collected, by whom, when the collection was made, and additional information such as what plant species were found in association with the collected specimen. There are no exotic species noted as associates on 39 of the 40 acuña cactus specimen herbarium sheets located at the Arizona State University, University of Arizona, or San Juan College Herbarium collections (ARIZ 2011, entire). These collections cover the range of the acuña cactus and date from 1952 through 2009. There was one specimen collected in 1982 that lists the exotic annual red brome grass as an associate. Although crimson fountaingrass found on nearby property was reported to be a possible threat to the acuña cactus near Ajo (Falk 2005, pers. comm.), no exotic grasses were noted within the Ajo, Little Ajo Mountains, or Coffeepot ACEC habitats

during field surveys in October 2011 (Service 2011, p. 4). One researcher familiar with all known populations of the acuña cactus noted no associated threats from exotic plant species in any population (Baker 2011, pers. comm.). In addition, researchers at OPCNM noted no present threats from any exotic plant species either within OPCNM or in populations of the Sonoran Desert National Monument (Rutman 2011, pers. comm.).

In summary, we have reviewed the available information on the effects of and occurrence of nonnative, invasive plants in or near populations of the acuña cactus in southern Arizona and in Mexico. Known populations of the acuña cactus are well distributed across southern Arizona and northern Sonora and occur in areas subject to effects from nonnative, invasive plant species. However, there are no populations of the acuña cactus that currently show evidence of effects from nonnative, invasive species, and just one 1982 report indicates the presence of an exotic plant as an associate of the acuña cactus. While nonnative, invasive species could negatively impact this species, our review of the best available information indicates nonnative species do not co-occur with the acuña cactus presently; therefore we conclude nonnative, invasive species do not pose a threat to the acuña cactus and its habitat.

Mining

The immediate threats from mining activity include the direct loss of individuals and habitat. Indirect impacts of mining activity include fragmentation of acuña cactus and associated pollinator populations, which can reduce genetic vigor of the cactus and result in degradation and fragmentation of habitat and dusting of individual cacti adjacent to mines and associated roads. The acuña cactus populations in OPCNM and the Sonoran Desert National Monument are protected from the immediate threats associated with mining due to their National Monument status (NPS 1997, pp. s-iii; BLM 2011, p. 12). Currently on the Coffeepot ACEC, mineral exploration and mining are encouraged (BLM 1988, pp. 55 and 71). The 2011 Draft RMP/EIS for the Sonoran Desert National Monument proposes to continue the mining closure within the Sonoran Desert National Monument (BLM 2011, p. 181). However, within this same document, alternatives outlined for the Coffeepot ACEC allow for mining activities, but with various restrictions depending on the alternative selected. Because mining of metallic and nonmetallic minerals will continue to be allowed within the Coffeepot ACEC under the revised Draft RMP/EIS (BLM 2011, pp. 154, 155, 196, 197), there is the continued potential for some loss of individual acuña cactus and fragmentation of acuña cactus and associated pollinator populations and habitat. There are no known mining activities planned on BLM properties, though a BLM parcel adjacent to populations on State lands near Florence may host a gravel mining operation in the future (Service 2011b, p. 1).

Mining activity on private land near Ajo has a long history; the New Cornelia copper mine was one of the first open pit mines in Arizona dating to 1854 (Arizona Mining Association 2011, entire). This mine was closed in 1985, and a 2008 investigation by company owners determined the mine would not be reopened due to current economic conditions (Ajo Copper News Oct 29, 2008). As of 2012, the mine remains closed.

The small populations of the acuña cactus that remain in Ajo may have been part of a much larger population that occurred before mining activity began, but there are no survey records for this species in the area prior to mining activity. As a result, it is unclear to what extent the acuña cactus and associated habitat were removed due to historical mining in this area, but there was certainly some loss of individual acuña cactus and habitat. Rutman (1995, p. 1) noted that on the east side of the Ajo rock dump, roads, wells, prospecting holes, rock piles marking mining claims, and past use of explosives occurred immediately adjacent to the acuña cactus plants. Rutman (2006, p. 1) noted that habitat was lost when Indian Hill Village Road was built and that occupied habitat may also have been lost where the following buildings and infrastructure now occur: Assembly of God Indian Mission, New Cornelia mine, parking lot for the mine lookout, baseball diamond, and the large informal parking lot to the north of the hill. It is possible that these populations were at one time connected with the few plants to the southeast of the open pit mine on BLM land. There is little doubt that the historical size and range of the Ajo area populations of acuña cactus have been reduced.

Mining threats on private lands near Florence are unknown. Threats from mining to the acuña cactus plants in Mexico are unknown.

We are aware of no acuña cactus populations that are currently impacted by active mining. It is reasonable to project that some mining will occur in the future that could affect acuña cactus populations near Florence, Ajo, and in the Coffeepot ACEC. However, these effects will occur in limited areas that do not support a majority of known individual acuña cactus. The acuña cactus populations will remain well distributed across their range even if future mining activities affect a few populations. Therefore, based on our review of the available information, we conclude that current and future mining activity is not a threat to the acuña cactus and its habitat.

Drought and Climate Change

Our analyses under the Act include consideration of ongoing and projected changes in climate. The terms “climate” and “climate change” are defined by the Intergovernmental Panel on Climate Change (IPCC). “Climate” refers to the mean and variability of different types of weather conditions over time, with 30 years being a typical period for such measurements, although shorter or longer periods also may be used (IPCC 2007, p. 78). Thus, the term “climate change” refers to a change in the mean or variability of one or more measures of climate (e.g., temperature or precipitation) that persists for an extended period, typically decades or longer, whether the change is due to natural variability, human activity, or both (IPCC 2007, p. 78). Various types of changes in climate can 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 the effects of interactions of climate with other variables (e.g., habitat fragmentation) (IPCC 2007, pp. 8-14, 18-19). In our analyses, we use our expert judgment to weigh relevant information, including uncertainty, in our consideration of various aspects of climate change.

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). Current climate change predictions for terrestrial areas in the Northern Hemisphere indicate warmer air temperatures, more intense precipitation events, and increased summer continental drying (Field

et al.

1999, pp. 1-3; Hayhoe

et al.

2004, p. 12422; Cayan

et al.

2005, p. 6; Seager

et

al.

2007, p. 1181). Climate change may lead to increased frequency and duration of severe storms and droughts (Golladay

et al.

2004, p. 504; McLaughlin

et al.

2002, pp. 6072-6074; Cook

et al.

2004, p. 1015).

The current prognosis for climate change impacts in the American Southwest includes 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) (Weiss and Overpeck 2005, p. 2074; Archer and Predick 2008, p. 24). How climate change will affect summer precipitation is less certain, because precipitation predictions are based on continental-scale general circulation models that do not yet account for land use and land cover effects or regional phenomena, such as those that control monsoonal rainfall in the Southwest (Weiss and Overpeck 2005, p. 2075; Archer and Predick 2008, pp. 23-24). Some models predict dramatic changes in southwestern vegetation communities as a result of climate change (Weiss and Overpeck 2005, p. 2074; Archer and Predick 2008, p. 24), especially as wildfires carried by nonnative plants (e.g., buffelgrass) potentially become more frequent, promoting the presence of invasive, exotic species over native ones (Weiss and Overpeck 2005, p. 2075). The Sonoran Desert has experienced drought conditions since 1998 (Bowers 2005, p. 421; WRCC 2012, entire). Recent trends for the region predict that climate of the region will become much drier in the next 2 to 3 decades (Schwinning

et al.

2008, p. 14-15). The impact of current and future drought, which may be long-term and severe (Seager

et al.

2007, pp. 1183-1184; Archer and Predick 2008, entire), will continue to affect the acuña cactus and its habitat throughout its range.

Climate change is likely to affect the long-term survival and distribution of native plant species, such as the acuña cactus, through changes in temperature and precipitation. Over the past 40 to 50 years, the United States has experienced more extreme weather events, heat waves, and regional droughts than in previous decades (Karl

et al.

2009, p. 27). The southwestern United States has experienced the greatest temperature increase in the continental United States; average temperatures increased approximately 0.8 degrees Celsius (°C) (1.5 degrees Fahrenheit (°F)) compared to a 1960 to 1979 baseline (Karl

et al.

2009, p. 129). By the end of this century, temperatures averaged across the Southwest region are expected to warm a total of 2 to 5 °C (4 to 10 °F) above the historic baseline period of 1960-1979 (Karl

et al.

2009, p. 129). The frequency and intensity of high temperature extremes will increase, and heat waves currently considered rare will become more common (Karl

et al.

2009, pp. 33-34). This region has experienced drought conditions since 1998 (Bowers 2005, p. 421; Western Region Climate Center (WRCC) 2012, entire). Annual mean precipitation levels are expected to decrease in western North America and especially the southwestern States by midcentury (IPCC 2007, p. 8; Seager

et al.

2007, p. 1181; Girvetz

et al.

2009, entire). The current trend in the Southwest of less frequent, but more intense, precipitation events leading to overall drier conditions is predicted to continue (Karl

et al.

2009, p. 24). The levels of aridity of recent drought conditions and perhaps those of the 1950s drought years will become the new climatology for the southwestern United States (Seager

et al.

2007, p. 1181). In summary, the drought the southwestern United States has been experiencing since the late 1990s is the worst in over 100 years and is being exacerbated by record warming (Karl

et al.

2009, p. 130).

Heat stress in adult cacti is minimal compared to other plant species as they are able to survive heat stress due to both morphology and metabolism (Smith

et al.

1984, pp. 647, 650; Wahid

et al.

2007, p. 199). In a study of Sonoran Desert cacti, Smith

et al.

(1984, pp. 647, 650) found that short cacti (such as the acuña cactus) and massive cacti had higher heat tolerance than most other cacti species studied, and more than vascular plants overall. They also found heat tolerance varied with stem orientation, stem diameter, and location on the landscape including a portion of the species' range (Smith

et al.

1984, p. 649). Extreme temperatures can, however, negatively impact seedling survival in many Sonoran Desert plants, and drought coupled with high temperatures lessens temperature tolerance in seedlings (Nobel 1984, pp. 310, 316). We found no additional information on projections for cacti in general, or the acuña cactus in particular, indicating the impacts of increased heat stress combined with increasing drought stress as climate models project. We do know, however, that drought or high temperatures alone can damage non-cacti species, and the combination causes more detrimental interactive effects on these plants than either stressor independently (Huang and Jiang 2002, p. 288).

We are aware of several reports of drought stress apparent on individual acuña cactus. In cacti and other succulents, stem swelling and shrinking is typical with rain-drought cycles (Mauseth 2000, p. 1107). At OPCNM, monitored acuña cactus individuals were reported to have shrunk in size from one year to the next, and researchers noted shrinking individuals may be dying (Ruffner 1989, p. 1). In addition, 1986 datasheets from monitoring plots at OPCNM categorized cacti based on health of the individual; one category from the time was “desiccated” (dried out) (Buskirk 1986, pers. comm.). Although such descriptive categories have not been in use in monitoring for some time, OPCNM staff note their importance and would like to reinstate them in future monitoring (Holm 2012b, pers. comm.). In addition, plants already stressed from prolonged drought are more susceptible to insect attack and disease (Mattson and Haack 1987, p. 110), and such attack is prevalent in all acuña cactus populations across their range (see discussion in

Factor C. Disease or Predation

). Mortality in measured plots at OPCNM was most severe in 1993, when 40 adults were lost, and again in 1997, when 53 adults were lost; both of these were years with dry summers (WRCC 2012, entire). In the last decade, 78 adults were lost in these plots, and 25 of these losses occurred in the very dry year of 2007 (WRCC 2012, entire). During this same 10-year period, 31 new adults were recorded as additions to the population through recruitment (NPS 2011a, p. 2).

In addition to the health of adult individuals, drought is directly related to acuña cactus population health with regard to reproduction and establishment. In his 3-year study of the reproductive ecology of the acuña cactus, Johnson (1992, pp. 403, 405) concluded that the positive association of rainfall and annual variation in the number of flowers produced indicates that water availability limits flower production in this species. Although Johnson cites yearly precipitation in relation to flower production, it seems more likely that winter precipitation is the driving factor, as flowers are produced early in the spring following winter precipitation events. Within monitoring plots established by Buskirk in 1977 (Buskirk 1981, p. 1), total flowers counted peaked at 902 in 1992 (Holm 2006, p. 10); corresponding precipitation during the winter of 1992-1993 was 29.7 cm (11.66 in) (WRCC 2012, entire). By comparison, in the last 10 years of measurement, the average number of flowers counted in these plots was 198 (Holm 2006, p. 10); the corresponding average winter

precipitation during these years was 9.7 cm (3.8 in) (WRCC 2012, entire).

Resource limitation may affect the acuña cactus seed set through ovule abortion (Johnson 1989, p. 11). Because flowering commences in early March and fruiting commences in late April (Johnson 1989, pp. 5, 8), it is likely also that winter precipitation is correlated with fruit set. Fruit production was monitored at the OPCNM plots beginning in 2004, and has shown considerable variation since that time, with a low of 29 fruits produced in 2007, when total winter precipitation was 6.8 cm (2.69 in) and, a high of 361 fruits produced in 2005, when winter precipitation was 16.4 cm (6.47 in) (NPS 2011a, p. 1; WRCC 2012, entire).

Johnson (1989, pp. 5, 12) determined that acuña cactus seedling survival was dependent on summer precipitation and that soil moisture availability limits the distribution of the species. Rice (2001, pers. comm.) noted that in greenhouse trials of the acuña cactus, seedlings and new recruits were primarily lost due to desiccation; emphasizing that establishment is the most critical and limiting phase of the acuña cactus life cycle. Throughout the species' range, rainfall has been declining, and drought conditions have been dominant since 1998 (Bowers 2005, p. 421; WRCC 2012, entire); this has likely influenced seedling survivorship (Holm 2006, p. 2-1—2-13; NPS 2011a, p. 1). For example, in the measured plots at OPCNM, the recruitment rate peaked in 1992, coinciding with consecutive seasons with near to above average rainfall (NPS 2011a, p. 1; WRCC 2012, entire). In the Coffeepot Mountain BLM monitoring plots, seedling or juvenile plants were observed in all years when plots were measured; however, the number of dead plants far exceeded recruitment in any year (Butterwick 1982-1992, entire). In many site visits throughout the region over the past 10 years, there have been reports of low or no recruitment (Service 2008a, p. 1; Service 2008c, p. 1; Anderson, 2011, p. 2; Service 2011a, entire; Service 2011b, p. 3).

In summary, since the late 1990s, the southwestern United States has been experiencing drought conditions and increasing high temperatures. Climatic predictions suggest continued less frequent, but perhaps more intense, summer precipitation, reduced winter precipitation; and increasing temperatures in this region (Seager

et al.

2007, p. 1181; Archer and Predick 2008, pp. 23-24; Karl

et al.

2009, p. 24). Data from the acuña cactus monitoring plots at OPCNM and at Coffeepot Mountain, along with occasional surveys of these and most other populations, indicate major population declines have occurred across the acuña cactus range over the past 30 years. It appears that a combination of drought stress, warmer winters, and insect attack (see

Factor C. Disease or Predation,

below) have reduced adult plant numbers, while heat stress, lack of precipitation, and seed predation (see

Factor C. Disease or Predation,

below) have combined to reduce or halt reproduction. Because the current drought is occurring on a regional scale, and because climatic models predict future regional droughts, it is likely that all populations of the acuña cactus will continue to decline due to drought and the effects of climate change. In addition, it appears that drought and climate change in combination with insect damage and predation, as a combined effect, is the more likely scenario for rangewide level impacts to acuña cacti (see

Factor C. Disease or Predation,

below). Most, if not all, of the acuña cactus populations are impacted by drought and the effects of climate change, including effects to both individual cacti and to productivity and establishment. Therefore, based on our review of the available information, we conclude that drought and the effects of climate change, combined with insect predation (see

Factor C. Disease or Predation,

below), rise to a rangewide level threat.

Summary of Factor A

In conclusion, based on our review of the best available information, we have determined that individual plant loss, as well as fragmentation of acuña cactus and associated pollinator populations due to the effects of urbanization; livestock grazing; nonnative, invasive plant species; and mining do not impact the species at a population level and therefore are not threats to the acuña cactus. Currently, 78 percent of the known living acuña cactus individuals occur along the border near OPCNM. Cross-border violators and associated CBP and LE off-road activities may be affecting individual acuña cactus plants and their habitat. If there is an increase in off-road activities in or near acuña cactus populations or habitat, the likelihood of loss of individuals or loss or modification of habitat also increases. In addition, a large amount of mortality has been documented within all populations that have been visited more than once, relating to a combination of the intricately correlated increases in drought and heat stress, warmer winter temperatures, and insect attack (see

Factor C. Disease or Predation,

below). Thus, based on our review of the best available scientific information, we conclude that loss and degradation of habitat due to off-road border activities, drought, and climate change, are threats to the acuña cactus and its habitat.

Factor B. Overutilization for Commercial, Recreational, Scientific, or Educational Purposes

Unauthorized collection has, in the past, been identified as a threat to the acuña cactus (Phillips

et al.

1982, p. 9; Phillips and Buskirk 1982, p. 2; Rutman 1996a, pers. comm.; Rutman 2007, p. 6). At OPCNM, a large number of individuals are located adjacent to Puerto Blanco Drive, which was formerly a scenic loop drive. Although historically collection is suspected to have occurred in this population (Buskirk and Phillips 1983, pers. comm.; Rutman 1996a, pers. comm.), the significance of this past collection varies. Buskirk (1981, p. 5) noted that he did not believe collection was a significant source of mortality between 1977 and 1981, yet Phillips and Buskirk (1982, p. 2) noted three mapped roadside cacti lost to collectors, stating that collecting could be a significant cause of loss in OPCNM. Additionally, Rutman (1996a, p. 2) noted that along the scenic drive road at OPCNM, considerable collection of the largest size class of plants occurred. This road was closed to visitors in 2003, and there are no plans to reopen it, making it highly unlikely that collection is an ongoing issue (Rutman 2011, pers. comm.; Pate 2012a, pers. comm.).

On BLM-administered lands, the acuña cactus plants occur in very remote locations, and no reports of collection are known. Rutman (1995, p. 2) noted collection did not appear to be a threat to the population surrounding the Coffeepot Mountain plots during annual visits between 1988 and 1990. Similarly, no evidence of collection was seen during 2011 Service and BLM site visits to nearby populations within the Coffeepot ACEC (Service 2011a, p. 4).

On State and private lands in the Florence area, Rutman (1995, p. 3) noted that population locations were published and, easy to access, and that, for many years, collectors have been taking plants. She also noted individual plants seen the previous year were missing, and no carcasses found upon revisiting (Rutman 1995, p. 3). No evidence of collection from visited sites was found during 2011 Service visits (Service 2011b, p. 1). Private lands in the Ajo area are also accessible, though we have no reports of collection there.

Buskirk and Phillips (1983, pers. comm.) refer to some acuña cactus collection, but refer to it as relatively uncommon and unsystematic at present. No documented cases of unauthorized

collection (in violation of the Arizona Native Plant Law) of this cactus have been found in any of the known populations. Heil and Melton (1994, p. 15) note that the acuña cactus is easy to grow and raise from seed and that species is rare in the gardens of cactus collectors. An investigator within the Office of Special Investigations of the Arizona Department of Agriculture stated that he does not believe collection of the acuña cactus is a threat to the species (Reimer 2011, pers. comm.). Therefore, based on our review of the available information, we conclude that, while there is evidence that unauthorized collection of the acuña cactus did occur in the past, it occurs to such an insignificant extent currently that it is not a threat to the acuña cactus, nor do we expect it to become a threat in the future.

Factor C. Disease or Predation

In general, cacti are susceptible to attacks from numerous types of insects, and the acuña cactus is no exception. The interior flesh of cacti provides both a nesting area and food source for beetles, weevils, and other insects. Once an infestation has occurred, cacti can die from the eating and tunneling activities or from the introduction of fungus or disease. In addition, drought may cause physiological stress responses in plants, such as limiting their photosynthesis and cell growth. Plants already stressed from prolonged drought are more susceptible to insect attack and disease (Mattson and Haack 1987, p. 110).

There are four native insects that have been documented to impact the acuña cactus. Of these, cactus weevils (

Gerstaeckeria

spp.) and cactus longhorn beetle (

Moneilema gigas

) are documented to be most responsible for the acuña cactus declines (Rutman 2007, p. 6; Johnson 1989, p. 10). Cactus weevils are stem-boring insects; the adults feed externally while the larvae feed internally (Burger and Louda 1995, p. 1560). Cactus longhorn beetle adults feed on pads or terminal buds of cacti; their larvae burrow into stems or roots causing the severing of root and stem, collapse, and death of plants (Kelly and Olsen 2011, p. 7; Johnson 1989, p. 10). Raske 1966 (p. 106) cites Dodd (1927) stating that the cactus longhorn beetle has one reproductive cycle per year; however, a noted cactus expert, Alan Zimmerman, believes that increased warming in recent decades facilitates longer breeding cycles and more reproduction in both the cactus longhorn beetle and cactus weevil (Rutman 2007, p. 6).

Other insects with lesser impact on the acuña cactus are snout moth (

Yosemitia graciella

) larvae and unknown ant species. Snout moth larvae are noted to feed internally on cacti (Simonsen and Brown 2009, entire) and on fruits, thus reducing seed set (Johnson 1992, p. 405). Johnson (1992, p. 405) noted snout moth predation accounted for a reduction in seed set of 35 percent in 50 monitored plants at OPCNM. Ants have been noted in greenhouse conditions and in the wild to consume and transport the acuña cactus seeds (Butterwick 1982-1992, entire; Rutman 1996b, pers. comm.; Rutman 2001, pers. comm., p. 1; Anderson 2011, p. 1). In a similar species,

Coryphantha robustispina

ssp.

robustispina

(Pima pineapple cactus), ants have been documented eating fruits and transporting seeds (Baker 2011, pp. ii, 23). While ants do consume seed, they also scatter seed away from the mother plant thereby reducing predation by small mammals (O'Dowd and Hay 1980, p. 536; Vander Wall

et al.

2005, p. 802). Ants may also aid in reducing the seedbank of competing plant species (O'Dowd and Hay 1980, p. 539). All of the above-mentioned insects have been documented at OPCNM near or on acuña cactus individuals (Johnson 1989, p. 10; Johnson 1992, p. 405; Rutman 1996b, pers. comm.; Rutman 2001, pers. comm., p. 1), with ants documented at Coffeepot Mountain (Butterwick 1982-1992, entire). It is likely that insect depredation occurs in other populations as well, though studies have not been conducted, and insects have not been collected in these populations. No diseases have been documented in the acuña cactus, though plants are exceptionally susceptible to bacterial rot after minor stem damage (Rutman 2007, p. 3). In 2011 site visits across the species' range, a majority of living adult acuña cacti were in various stages of decline, with stems blackening from the base upward and resulting in eventual cactus death. The cause of this blackening is unknown; it could be natural aging of the plants or the result of stress, insect damage, or disease.

A variety of small mammals, such as native ground squirrels, pack rats, rabbits, and mice, can severely damage or kill both mature and young cacti during times of drought (Kelly and Olsen 2011, pp. 8-9). There have been reports of loss of the acuña cactus due to small mammal depredation evidenced by scattered spines and rooted bases at OPCNM (Buskirk 1981, p. 5; Buskirk and Phillips, 1983 pers. comm.; Heil and Melton 1994, p. 15; Holm 2006, pp. 2-3). It is likely that small mammal depredation occurs in other populations outside of OPCNM as well, though studies have not been conducted and small mammal occurrence in these populations has not been documented.

In 2011, nearly all populations of the acuña cactus on BLM, State, and some private lands were visited by Service staff (Service 2011a, entire; Service 2011b, entire). In every population, some partially living and dead plants were found uprooted and toppled over. In 1996, there was a high mortality event associated with many live, reproductive plants found uprooted and lying on the ground in the Coffeepot Mountain population and the populations around Ajo (Rutman 2007, p. 3). There has been no explanation for this episode; however, there have been various hypotheses including vandalism, thrashers (birds) digging them up, and javelinas uprooting the plants. Given the severing of stem from root commenced when plants had been infested with cactus longhorn beetle, it is entirely possible that episodes of plants falling over occur following peak years for these insects, possibly in association with birds or other animals hearing and attempting to remove the insects within. There were above average temperatures in Ajo the 2 years preceding the 1996 uprooting event; this uprooting may have been correlated to increased insect activity and uprooting. There have been above average annual temperatures recorded at the Ajo Weather Station 15 times during 25 years of record keeping between 1975 and 2010 (WRCC 2012, entire). This trend is consistent both at OPCNM and in Florence, where 21 of 25 recent years and 19 of 25 recent years, respectively, had above average temperatures (WRCC 2012, entire). The increased warming in recent decades is likely benefiting insects and stressing acuña cactus plants, resulting in significantly increased mortality rangewide.

Between 1982 and 1992, both recruitment and mortality were recorded within and outside of the established BLM plots at the Coffeepot Mountain acuña cactus population. Field notes from throughout the 10-year period of study indicate insect damage to individual plants has been ongoing within this population. Field notes included the following comments: tubercles with holes, damage on apex, exposed root, numerous ants, plant dying, insect damage to fruit, hollow inside, uprooted, chlorotic (yellowing), beetle wounds on side, unhealthy, damaged meristem, appears dying at the base, base rotting, sickly, and not rooted (Butterwick 1982-1992). In 1987, the

BLM reported high mortality in this population with more dead plants observed (332) than living (310) (Rutman

et al.

1987, p. 1). In 1989, the BLM reported a precipitous decline of this population (Johnson 1989, p. 18) with low or no recruitment since that time (Anderson 2011, entire). Within the monitoring plots at OPCNM, datasheets from 1986 categorized cacti as being: uprooted from the base, shell of spines, dead with upright carcass, stepped on, and missing, among others (Buskirk 1986, pers. comm., entire). Within these plots, adult recruitment has been observed in every year of monitoring since 1989; mortality has been observed in all but 2 years during this same period (NPS 2011a, p. 1). On average, the annual adult mortality within these plots is 12 percent, exceeding the annual recruitment of 7.7 percent (NPS 2011a, p. 1). The decrease in reproduction, increase in mortality, or a combination of both have resulted in the decline in plants within (NPS 2011a, p. 1) and outside of the plots at OPCNM. Across this population, the previous estimate of acuña cactus numbers were greater than 10,000 individuals (Buskirk 1981, p. 3); current estimates are between 1,000 and 2,000 plants total (Rutman 2011, pers. comm.).

Within monitoring plots at Coffeepot Mountain, population decline has been dramatic with at least two episodes of 50 percent reductions reported from individuals in and around monitoring plots (Butterwick 1982-1992, entire; Rutman

et al.

1987, p. 2; Anderson 2011, p. 2; Anderson 2012b, pers. comm.); at OPCNM, there has been a documented decline in the number of individuals on all six monitoring plots in all but 2 years since 1989 (NPS 2011a, p. 1), and in total population estimates between 1981 and 2011 (Buskirk 1981, p. 3; Rutman 2011, pers. comm.). In 2011, site visits to most of the remaining populations on BLM, State, and private lands indicated large proportions of the populations were dead with many plants uprooted, hollow plants, and many individuals in all size classes reported to be unhealthy or blackening from the base (Service 2011a, entire; Service 2011b, entire). Also in 2011, researchers in Mexico reported that 58.8 percent of the 1,601 total plants found were dead (Pate 2012b, pers. comm.).

In conclusion, uprooting and depredation have been ongoing for at least several decades at OPCNM, at Coffeepot Mountain, and in all other populations. The pronounced decline in the acuña cactus numbers over the last three decades documented throughout the species' range on BLM, State, private, and lands in Sonora, Mexico, is of serious concern. It appears that the combination of drought stress and insect attack have reduced adult plant numbers and that warmer winters may be increasing insect numbers attacking acuña cacti. Most, if not all, of the populations are significantly impacted by predation; predation, in the form of insect attacks, occurs throughout the range of the acuña cactus. We also believe that the extent to which this threat affects the acuña cactus populations is interactive with the occurrence of drought and other climatic variables such as warmer winters. The ability of the acuña cactus populations to recover from insect attacks depends on the successful germination and survival of seedlings. However, these populations are also experiencing decreased reproduction, which may render the populations unable to recover as they continue to lose mature individuals, with low levels of seedling recruitment and survival. Therefore, based on our review of the available information, we conclude that predation is a threat that is resulting in significant population impacts to the acuña cactus, and this threat is expected to continue into the future.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

Under this factor, we examine whether existing regulatory mechanisms are inadequate to address the threats to the species discussed under the other factors. Section 4(b)(1)(A) of the Act requires the Service to take into account “those efforts, if any, being made by any State or foreign nation, or any political subdivision of a State or foreign nation, to protect such species * * *.” We interpret this language to require the Service to consider relevant Federal, State, and Tribal laws, plans, regulations, cooperative agreements, and other such mechanisms that may minimize any of the threats we describe in threat analyses under the other four factors, or otherwise enhance conservation of the species. We give strongest weight to statutes and their implementing regulations and management direction that stems from those laws and regulations. An example would be State governmental actions enforced under a State statute or constitution, or Federal action under statute.

Having evaluated the significance of the threat as mitigated by any such conservation efforts, we analyze under Factor D the extent to which existing regulatory mechanisms are inadequate to address the specific threats to the species. Regulatory mechanisms, if they exist, may reduce or eliminate the impacts from one or more identified threats. In this section, we review existing State and Federal regulatory mechanisms to determine whether they effectively reduce or remove threats to the acuña cactus.

Regarding the threat of unauthorized collection, the acuña cactus is protected by the Arizona Native Plants Law, which prohibits collection without obtaining a permit on all public lands, and directs that plants may not be moved off of private property without contacting the Arizona Department of Agriculture. Due to the difficulty in implementing this law, it has not been effective in reducing impacts from collection, nor does it protect habitat. However, no documented cases of unauthorized collection of this cactus have been found in any of the known populations in recent decades. There is little threat of collection on private lands due to restricted public access (see Factor B); the majority of the acuña cactus populations are on State and Federal lands. In addition, NPS regulations prohibit the collection or removal of the acuña cactus on NPS lands, where the largest known acuña cactus population occurs. The main road accessing the acuña cactus population in Acuña Valley in OPCNM is closed to the public, thus reducing impacts from collection to this population. Although the remoteness of many populations limits both visitation and enforcement of the existing regulatory mechanisms, unauthorized collection is reported to result in a relatively minor impact to this species. We conclude that the regulations that exist to protect against the impacts from over collection of the species, primarily the NPS regulation prohibiting removal and the closure of the primary access route in OPCNM, are serving to reduce the impacts from collection.

There are no regulations in place that address threats to acuña cactus and its habitat from site degradation or that address the primary threats to acuña cactus of insect predation, drought, and the effects of climate change. Urban development; livestock grazing; nonnative, invasive plant species; unauthorized collection, and mining are not identified to occur at a level that is a threat to acuña cactus populations. However, without management of impacts from these activities, impacts could rise significantly. There are special management prescriptions in place to address some of these concerns on Federal lands. For example, the Sonoran Desert National Monument and OPCNM exclude livestock grazing and mining; promote the reduction of

nonnative, invasive plant species; and are unlikely to support urban development. In Mexico, a portion of the known population is within the boundary of Pinacate Biosphere Reserve, which may afford some protections. While management prescriptions with regard to these stressors may be applied opportunistically across different land management agencies within the region, they do afford some protection and minimize impacts to the species and its habitat.

With respect to threats to the species caused by activities along the U.S.-Mexico border, there are a number of Memorandum of Understanding and Biological Opinion documents that dictate certain actions be taken by CBP to reduce effects to resources in the United States and Mexico border region. These documents are primarily associated with habitat of the federally listed Sonoran pronghorn antelope (

Antilocapra americana

ssp.

sonoriensis

) and off-road activity, specifically identifying sensitive areas to avoid. These Memorandum of Understanding and Biological Opinions do provide some relief from the threats caused to the species resulting from cross-border violators and CBP enforcement activities because the acuña cactus shares a portion of the pronghorn habitat and these documents limit some direct impact to habitat. Likewise, CBP-sponsored projects, including the mapping of off-road tracks and revegetating unauthorized roads, may also benefit the species (Holm 2012a, pers. comm.). In cooperation with Service staff, CBP has begun efforts to educate Border Patrol agents on the locations and appearance of acuña cactus so that areas that support the species can be avoided to the maximum extent possible. Designated critical habitat in OPCNM will be marked on road atlases being prepared by OPCNM staff and provided to the agents patrolling in the OPCNM area. In addition, the efforts of CBP to stop cross-border violators in recent years by means of traffic barriers and other infrastructure has greatly reduced cross-border violator activities and afforded some protection to the habitat. However, due to the difficulty and ever-changing status of border issues, compliance with these agreements has been difficult. Reports indicate a two-track road and associated cross-border violator clothing were found in 2010 within one of the six long-term monitoring plots at OPCNM. The cross-border violator activities are, by their very nature, in violation of the law and regulations. Therefore, we believe that regulations designed to protect the species and its habitat will be generally of little impact to alleviate the threats caused by activities of cross-border violators. As noted above, the interdiction efforts of the U.S. Border Patrol (USBP), including patrols, electronic surveillance and fence construction have contributed to a significant reduction in cross-border violator off-road traffic that has benefited the acuña cactus and other species. However, we do not find regulatory mechanisms to be adequate to directly address these threats discussed in Factor A.

Factor E. Other Natural or Manmade Factors Affecting Its Continued Existence

We have evaluated the best available scientific information, and we did not find any indication of potential threats related to this factor. We considered such threats as small population size and overall rarity of the acuña cactus, but we did not find any indication that these are threats to the species. Therefore, we conclude that other natural or manmade factors are not threats to the acuña cactus.

Proposed Determination for the Acuña Cactus

We have carefully assessed the best scientific and commercial information available regarding the past, present, and future threats to the acuña cactus. We find that the species is in danger of extinction due to the current and ongoing modification and destruction of its habitat and range (Factor A) from long-term drought, effects of climate change, and ongoing and future border activities. The acuña cactus habitat is impacted across its range by long-term drought, warmer winters occurring in the past several decades and projected to continue with climate change, and insect predation. In addition, the majority of the acuña cactus individuals (78 percent) occur within 16.5 km (10.25 mi) of the border in either OPCNM or Sonora, Mexico. As described above, the complexities of addressing off-road excursions by cross-border violators result in unpredictable actions on the part of CBP and LE and threatens acuña cactus and its habitat. The primary threats to the species are due to drought, climate change, and insect predation. These threats are exacerbated at local scales by off-road excursions by cross-border violators and CBP and LE response. We do not find any threats to the species from unauthorized collection (Factor B). We find that predation, in combination with drought and heat stress, exacerbates the threats to this species (Factor C). Although mechanisms are in place that afford some protection to the species and its habitat with regard to potential stressors to the species, there are no regulations in place to address insect predation, drought, and the effects of climate change. With regard to off-road border activity, although the interdiction efforts of CBP, including patrols, electronic surveillance and fence construction have contributed to a significant reduction in cross-border violator off-road traffic that has benefited the acuña cactus and other species, regulations have little impact to alleviate these threats. Therefore, we do not find regulatory mechanisms to be adequate to directly address these threats discussed in Factor A. Finally, we find other natural or manmade factors are not threats to the acuña cactus (Factor E).

The elevated risk of extinction of the acuña cactus is a result of the cumulative stressors on the species and its habitat. Mortality of more than 80 percent of individuals has been documented within populations that have been surveyed more than once. This loss has also occurred on protected lands with ongoing management efforts for the acuña cactus, showing both a rapid and a severe decline to the species. In the acuña cactus, water and heat stress reduce flower and seed production, and seedling survival is dependent on summer precipitation and soil moisture. Warmer and drier winters combined with increased insect attack, negatively impacts the survivorship of reproductive adults. Of the remaining living individuals across the species' range, a large portion were in various stages of deteriorating health, primarily blackening from the base upward, when visited by a botanist in 2011. Across populations, minimal or no recruitment has been seen in recent years. Throughout the species' range, rainfall has been declining, and drought conditions have been dominant for several decades; climate change is anticipated to increase drought periods and warming winters. This combination is expected to continue the documented trend of mortality exceeding recruitment across all populations. When mortality exceeds recruitment in a population, the result is often a declining population. Given this, we consider none of the populations to be stable or secure. The factors significantly threatening the species are not expected to be abated in the foreseeable future, and some populations may have decreased to levels where they are no longer viable. All of the threats, combined with high

levels of mortality and low recruitment in the populations, contribute to a substantial risk of extinction and lead to our finding that the acuña cactus is in danger of extinction throughout its range; therefore, the species meets the definition of endangered.

The Act defines an endangered species as any species that is “in danger of extinction throughout all or a significant portion of its range” and a threatened species as any species “that is likely to become endangered throughout all or a significant portion of its range within the foreseeable future.” We find that the acuña cactus is presently in danger of extinction throughout its entire range based on rangewide documented rapid loss of individuals, decline in the health of many remaining individuals, little to no recruitment, and continuation of the threats, as described above. Therefore, on the basis of the best available scientific and commercial information, we propose listing the acuña cactus as an endangered species in accordance with sections 3(6) and 4(a)(1) of the Act.

Listing the acuña cactus as a threatened species is not the appropriate determination because the ongoing threats described above are severe enough to create the immediate risk of extinction. The continued loss of reproductive adults and juveniles poses a significant and immediate risk of extinction to the species throughout the species' range, and are not restricted to any particular significant portion of that range. All of these factors combined lead us to conclude that the threat of extinction is high and immediate; thus, we conclude that the acuña cactus meets the definition of an endangered species.

Under the Act and our implementing regulations, a species may warrant listing if it is an endangered or threatened species throughout all or a significant portion of its range. The threats to the survival of the species occur throughout the acuña cactus' range and are not restricted to any particular significant portion of that range. Accordingly, our assessment and proposed determination applies to the species throughout its entire range.

Fickeisen Plains Cactus

It is our intent to discuss below only those topics directly relevant to the listing of the Fickeisen plains cactus as endangered in this section of the proposed rule.

Species Description

The Fickeisen plains cactus is a small, unbranched to occasionally branched, globose (globular) cactus that retracts into the soil after flowering and fruiting. Stems of mature Fickeisen plains cactus are 2.5 to 6.0 cm (1.0 to 2.4 in) tall and up to 5.5 cm (2.2 in) in diameter (Benson 1982, p. 749; Arizona Rare Plant Guide Committee 2001, unpaginated). The stems are covered with tubercles; each tubercle has 3 to 7 radial spines, 4 to 7 millimeters (mm) (0.15 to 0.27 in) in length, and 1 central spine (15 to 18 mm (0.59 to 0.70 in) long) that distinguishes the variety

fickeiseniae

from the variety

peeblesianus

(Benson 1982, p. 765). The central spine is whitish and curved upward. All spines are corky (spongy). The flowers are 2.5 cm (0.98 in) in diameter, cream-yellow or yellowish-green in color, and produced on the apex of the stem. Flowers bloom from mid-April to mid-May, opening in the mid-morning for 1 to 2 days. An entire population generally completes anthesis (the period when the flower is open and functional) in 7 to 14 days (Travis 1987, p. 6), depending on the weather conditions (Navajo Natural Heritage Program (NNHP) 1994, p. 4). Fruits are produced in mid-May, are turbinate (top-shaped), and turn reddish-brown at maturity (AGFD 2011a, p. 1). The seeds are dark brown to black, 3 mm (0.11 in) long, and 2 mm (0.08 in) wide (AGFD 2011a, p. 1). The life span of the Fickeisen plains cactus is estimated to be between 10 to 15 years (Phillips

et al.

1982, p. 9).

Taxonomy

The Fickeisen plains cactus was discovered near Cameron, Arizona, in the late 1950s, and was described in the scientific literature by Heil

et al.

(1981, pp. 28-31).

The name

Pediocactus peeblesianus

var.

fickeiseniae

had not been validly published. Heil

et al.

(1981, p. 31) recognized the name and taxon in a review of the genus

Pediocactus,

and this name is accepted in the Flora of North America (Heil and Porter 2003, p. 213). Based on these references, we consider

Pediocactus peeblesianus

var.

fickeiseniae

to be a valid taxon. Other synonyms of

Pediocactus peeblesianus

var.

fickeiseniae

that have been used are

Navajoa fickeisenii

and

Toumeya fickeisenii

(Benson 1982, p. 955).

The genus

Pediocactus

contains seven species; six of these are rare endemics of the Colorado Plateau region in Arizona, Colorado, New Mexico, and Utah (Benson 1982, p. 749). There are two recognized varieties of

Pediocactus peeblesianus,

variety

peeblesianus

(Peebles Navajo cactus) and variety

fickeiseniae

(Porter 2002, pp. 15-16). According to Benson, the structural differences exhibited by

Pediocacti

among various sites, coupled with a poor seed dispersal mechanism and specializations to specific geology or soil type, indicate that the existing plants are probably relicts of a once widespread genus with a distribution fractured by climatic conditions (Benson 1982, p. 750).

Biology

The general biology of the Fickeisen plains cactus is similar to other species in the genus

Pediocactus.

The Fickeisen plains cactus

is a cold-adapted plant that retracts into the soil during the winter (cold) and summer (dry) seasons, as well as during drought conditions. Plants may be completely buried underground or shrink down into the soil until the crown sits flushed with the soil surface (Phillips

et al.

1982, p. 4). When temperatures rise in the spring and with adequate rainfall, plants emerge from beneath the surface to flower in mid-April. Spring flowering is believed to be influenced by cold temperatures and precipitation from the preceding winter months (Brack 2012, pers. comm.). After flowering and prior to the summer heat, plants set seed in June and shrink into the soil, losing one-half their height above ground. Some plants may re-emerge in the autumn following monsoonal rains. The length of time a plant remains retracted can vary between individual plants. Hughes (2000a, p. 2) has documented some plants remaining retracted underground for at least 3 years. The Fickeisen plains cactus is also subject to root rot during very wet years and frost heaving. Locating individuals of the Fickeisen plains cactus can be difficult, even when their exact location is known, and therefore, searches are best done during their flowering period.

Reproduction has not been specifically studied on the Fickeisen plains cactus. However, reproduction for plant species in the genus

Pediocactus

occurs by cross-pollination (Pimienta-Barrios and del Castillo 2002, p. 79). Species of small native bees are the primary pollinators. Species of hover flies and bee flies have also been observed visiting flowers of the Fickeisen plains cactus (Milne 1987, p. 21; NNHP 1994, p. 3; Peach

et al.

1993, pp. 312-314; Tepedino 2000, p. 7; Tepedino 2012, pers. comm.). Hughes (1996a, p. 50) found that flowering and fruiting in the Fickeisen plains cactus occurs once an individual plant grows to 10 mm (0.39 in) in diameter and as an individual increases in size more fruit are produced. Specifically, he documented individuals less than 20.9 mm (0.82 in) in diameter produced 1.37 fruit on average (range of fruit produced

1 to 3) compared to individuals at 50 mm (1.97 in) and larger, which produced 3.60 fruits on average (range of fruit produced 2 to 5). This correlation between larger sized individuals and increased fruit production has also been found in other

Pediocactus

species (Phillips

et al.

1989, p. 4; Hreha and Meyer 2001, p. 86). This information suggests that larger, older individuals contribute more to the population growth rate by potentially having a greater influence on seed output than smaller, younger plants. Based on long-term monitoring information for the Fickeisen plains cactus, the majority of individuals observed tend to range between 20 mm (0.79 in) and 30 mm (1.18 in) in diameter.

Population monitoring of the Fickeisen plains cactus suggests that this variety has a low reproductive capacity. In examining long-term monitoring information by the BLM, fruit production occurred irregularly over a 22-year period with 35 percent, on average, of the population reproducing. Hughes (2011, pers. comm.) found that 30 to 40 seeds are generally produced from a single fruit, and believed that low seed production hinders substantial increases in plant abundance from occurring, even during favorable weather conditions that would support germination (Hughes 1996a, p. 50). Thus, significant episodes of recruitment within populations on BLM lands reportedly occurred two to three times over a 9-year period from 1986 to 1995 (Hughes 1996a, p. 50). Phillips and Phillips (1995, p. 12) reported similar results for the Peebles Navajo cactus in which they documented moderate increases in population numbers roughly two to three times every 10 years. Episodic recruitment may play a role in increasing the threats to the species because adult mortality may continue at a high rate between periods of recruitment, lowering the reproductive potential of the population when conditions are favorable for seed germination.

The mechanisms of seed dispersal in the Fickeisen plains cactus have not been investigated and are poorly understood. Most site visits to populations of the Fickeisen plains cactus have observed seedlings established very close to the adult plant (Goodwin 2011a, p. 9; NNHP 1994, p. 4). The general shared belief is that most species of

Pediocactus,

including the Fickeisen plains cactus, lack a good mechanism for seed dispersal, which is a contributing factor to its endemism and widely scattered, isolated populations (Benson 1982, p. 750; Milne 1987, p. 4).

Habitat

The Fickeisen plains cactus is a narrow endemic restricted to exposed layers of Kaibab limestone on the Colorado Plateau. Plants are found in shallow, gravelly loam soils formed from alluvium, colluvium, or Aeolian deposits derived from limestone of the Harrisburg member of the Kaibab Formation and Toroweap Formation; Coconino Sandstone; and the Moenkopi Formation (Travis 1987, pp. 2-3; Arizona Geological Survey (AZGS) 2011; Natural Resources Conservation Service (NRCS) 2012). Most populations occur on the margins of canyon rims, on flat terraces or benches, or on the toe of well-drained hills with less than 20 percent slope; at elevations between 1,280 to 1,814 m (4,200 to 5,950 ft) (Arizona Rare Plant Guide Committee 2001, unpaginated; AGFD 2011b, entire; Hazelton 2012a, pers. comm.). Habitat of the Fickeisen plains cactus is within the Plains and Great Basin grasslands and Great Basin desert scrub vegetation communities (Benson 1982, p. 764; NatureServe 2011). Dominant native plant species that are commonly associated with these biotic communities include:

Artemisia tridentata

(sagebrush),

Atriplex canescens

(four-wing saltbush),

Atriplex confertifolia

(shadscale),

Bouteloua eriopoda

(black grama),

Bouteloua gracilis

(blue grama),

Bromus

spp. (brome),

Chrysothamnus

spp. (rabbit-bush),

Ephedra torreyana

(Mormon tea),

Eurotia lanata

(winterfat),

Gutierrezia sarothrae

(broom snakeweed),

Pleuraphis jamesii

(James's galleta),

Oryzopsis hymenoides

(Indian ricegrass),

Sphaeralcea

spp. (globe-mallow), and

Stipa

spp. (needlegrass). Other native cactus species that are commonly found include

Agave utahensis

(century plants) and

Echinocactus polycephalus

spp. (Brown 1994, pp. 115-121; Turner 1994, pp. 145-155; Hughes 1996b, p. 2; Goodwin 2011a, p. 4; NatureServe 2011). The

Escobaria vivipara

var.

rosea

(foxtail cactus) is typically found in close association with the Fickeisen plains cactus (Hughes 1996a, p. 47).

The climate of the Great Basin Desert and on the Colorado Plateau is highly variable. The climate of the region is influenced by events in the tropical Pacific and northern Pacific Ocean (United States Geological Survey (USGS) 2002, p. 2). The amount of precipitation received locally varies by elevation and topography, and is patchy in its distribution. Precipitation is bimodal, occurring in the winter (January to March) and summer (July to September) months. The average annual precipitation ranges from 15.2 to 35.5 cm (6 to 14 in) per year; snowfall accumulation averages 22.9 cm (9 in), primarily from January to February (WRCC 2012, entire). Winter precipitation is thought to be critical for the region to ensure soil moisture recharge and a reliable spring growing season (Travis 1987, p. 3; Comstock and Ehleringer 1992, pp. 196-199).

Biological soil crusts are found on the Colorado Plateau in or near the Fickeisen plains cactus' habitat (United States Forest Service (USFS) 1999, entire; BLM 2007a, p. 3-15). Biological soil crusts are formed by a community of living organisms that can include cyanobacteria, green algae, microfungi, mosses, liverworts, and lichens (Belnap 2006, pp. 361-362). These crusts provide many positive benefits to the larger vegetation community by providing fixed carbon and nitrogen on sparsely vegetated soils, soil stabilization and erosion control, water infiltration, improved plant growth, and seedling germination (Rychert

et al.

1978, entire; NRCS 1997, pp. 8-10; Floyd

et al.

2003, p. 1704; Belnap 2006, entire).

Distribution and Range

The Fickeisen plains cactus is found only on the Colorado Plateau in Coconino and Mohave Counties. The range of the Fickeisen plains cactus encompasses the Arizona Strip (i.e., the area north of the Colorado River to the Arizona-Utah border) from Mainstreet Valley in Mohave County to House Rock Valley in Coconino County, along the canyon rims of the Colorado River and Little Colorado River, to the area of Gray Mountain, and along the canyon rims of Cataract Canyon on the Coconino Plateau. The majority of the populations are small; some consisting of a few individuals (Table 3). Populations are widely scattered over a broad range and separated by topography. There seems to be abundant suitable habitat that is unoccupied by the plant for reasons unknown. One estimate of the range of the Fickeisen plains cactus is 12,750 square kilometers (sq km) (4,922 square miles (sq mi)) (NatureServe 2011, p. 2). We do not know what information was used to derive this estimate, and, therefore, it may not accurately reflect the current known range. The range of the Fickeisen plains cactus

converges with the range of the endangered

Pediocactus bradyi

(Brady pincushion cactus) in House Rock Valley, and overlaps with the range of the threatened

Pediocactus sileri

(Siler pincushion cactus), and the

Pediocactus

paradinei

(Kaibab plains cactus), which is protected by a conservation agreement on the Arizona Strip (BLM 2011a, Figure 3.8-1).

Very little is known about the historical range of the Fickeisen plains cactus. Benson (1982, p. 765) described the range as northern Arizona from the hills in northeast Mohave County to the vicinity of the Colorado and Little Colorado rivers near the Grand Canyon National Park and southeast Coconino County. He estimated the known range to be about 200 km (125 mi) of land. Based on the current spatial distribution of the Fickeisen plains cactus, the plant's range has expanded roughly 72 km (45 mi) west of the Kaibab Plateau in Mohave County to include occupied areas in Mainstreet Valley, Hurricane Cliffs, and Clayhole Ridge on the Arizona Strip.

The Fickeisen plains cactus population near Cataract Canyon was recently documented in 2006. The population is located below the Colorado River and south of the Grand Canyon National Park on the Cataract Ranch but does not appear to represent a range expansion for the species. Benson had identified two areas as occupied by

Pediocactus peeblesianus

varieties that correspond to the location of this population (Benson 1982, p. 765). One area, located below the Colorado River, was identified as a Fickeisen plains cactus occurrence. The second occupied area was located farther south of there but identified as a Peebles Navajo cactus occurrence. Both of these areas were later inventoried as part of a floristic survey in 2006, and the variety of

Pediocactus peeblesianus

observed was documented as the Fickeisen plains cactus (Goodwin 2006, p. 4; Goodwin 2011a, pp. 5-6).

The Fickeisen plains cactus has also been documented on State land within the Boquillas Ranch, which is located to the west of the Cataract Ranch and is privately owned by the Navajo Nation (Goodwin 2006, p. 5; Chapman 2012, pers. comm.). Besides location coordinates, we do not have information describing the status of the Fickeisen plains cactus there. According to Goodwin (2006, pp. 4-5), two German botanists had discovered plants of

Pediocactus peeblesianus

on the Coconino Plateau in 1979, but the plants were thought to be of the variety

maianus.

Based on their field notes, visits to the area between 1980 and 2006 confirmed the locations of three occupied sites by the

Pediocactus peeblesianus,

later documented as the Fickeisen plains cactus. Two of these sites were on the Cataract Ranch while the third site is on State land leased to the Boquillas Ranch (Chapman 2012, pers. comm.). This area was revisited in 2012, but no documentation describing the site visit is available (Goodman 2012, pers. comm.; Hazelton 2012b, pers. comm.). Anecdotal information suggests that additional Fickeisen plains cacti and an abundant suitable habitat occur on the Boquillas Ranch (Chapman 2012, pers. comm. Goodwin 2012, pers. comm.). If additional Fickeisen plains cacti do exist here, it would increase the known range and distribution of the plant.

Abundance and Trends

About 1,150 Fickeisen plains cacti among 33 populations have ever been documented rangewide from 1962 to 2011 (Table 3) (AGFD 2011b, entire; Goodwin 2011a, p. 19; NNHP 2011a, entire). However, 504 individuals among 6 populations have been recently documented and are a subset of the 1,150 individuals. This difference in the number of individuals does not necessarily represent a decline; survey information for the remaining 27 populations is absent, and therefore their status is unknown. Additionally, the increase in plant numbers in the Cataract Canyon population from 2007 to 2011 is due to better detection between years and not to greater abundance. Based on these six documented populations, the breakout of the land ownership follows: BLM (26 percent), Kaibab National Forest (status unknown), State of Arizona (32 percent), the Navajo Nation (14 percent), and privately-owned lands (29 percent).

Table 3—Total Documented Fickeisen Plains Cactus Numbers

[1962 to 2011]

Population

Land owner

First visited

First count

Last visited

Last count

Beanhole Well

BLM

1979

3

1979

3

Marble Canyon

BLM

1979

8

1979

8

Gray Mountain (Mays Wash)

BLM

1981

29

1981

29

South Canyon

BLM

1979

41

1987

52

Toquer Tank

BLM

1986

8

1994

7

Navajo

BLM

1986

4

2001

10

Salaratus Draw I and II

BLM

1986

17

2001

0

Temple Trail

BLM

1986

7

2001

7

Ward

BLM

1986

12

2001

10

Sunshine Ridge II

BLM

1986

9

2004

35

Clayhole Ridge

BLM

1987

23

2011

42

Dutchman Draw

BLM

1986

167

2011

12

North Canyon

BLM

1987

16

2011

39

Sunshine Ridge

BLM

1987

12

2011

34

Kaibab National Forest

Forest Service

Unknown

2004

Unknown

Shinumo Wash

NN

1993

9

1993

9

Tiger Wash 2

NN

1993

11

1993

11

Little Colorado River Overlook

NN

1956

Unknown

1997

15

Little Colorado River Gauging Station

NN

1999

1 (survey out of season)

1999

1

29 mile Canyon

NN

2000

2

2000

2

Big Canyon

NN

2002

15

2002

15

West of Hellhole Bend

NN

2002

5

2002

5

Small Ridge

NN

2004

1 (survey out of season)

2004

1

Little Colorado River Gravel pit

NN

1956

Unknown

2005

21

Shinumo Altar

NN

1991

Unknown

2005

7

Tiger Wash 1

NN

1993

30

2005

2

Gray Mountain (South of Cameron)

NN

1962

4

2009

3

Hellhole Bend

NN

2009

314

2009

314

Salt Trail Canyon

NN

2006

119

2011

70

Blue Spring

NN

2005

30

2005

30

Gray Mountain (Sewage Disposal Pond)

Private

1984

1984

4

Cataract Canyon

Private

2007

54

2011

146

Cataract Canyon

State

2007

98

2011

161

TOTAL

1, 105

Notes:

Navajo Nation (NN).

Table 4—Numbers of Fickeisen Plains Cacti Recorded in BLM Monitoring Plots and Cluster Plots

[1986 to 2011]

Year

Dutchman

Clayhole

Sunshine Ridge

North Canyon

Navajo

Sunshine Ridge II

Salaratus I and II

Temple Trail

Toquer Tank **

Ward

Total

1986 Plants outside plots*

167

8

9

17

201

1986

21

6

14

4

2

5

8

10

70

1987

107

23

12

16

7

165

1988

102

35

27

9

173

1989

185

31

8

28

9

261

1990

186

32

33

33

6

290

1991

194

37

43

36

13

323

1992

219

44

44

7

7

321

1993

168

34

32

13

0

13

1

0

261

1994

168

38

35

16

44

7

308

1995

188

30

25

11

254

1997

122

21

7

21

171

1998

49

16

6

26

97

1999

45

17

5

28

95

2000

37

20

Not Observed

22

79

2001

40

63

3

34

10

23

0

7

0

10

190

2002

30

60

12

24

126

2003

50

56

Not Observed

24

130

2004

45

59

7

40

151

2005

34

59

33

40

166

2006

36

48

26

32

142

2007

32

38

30

39

139

2008

23

40

23

33

119

2009

33

37

33

31

134

2011

12

42

34

39

127

Notes:

* BLM reported counts of Fickeisen plains cacti outside of established monitoring plots for 1986 only. No monitoring occurred in 1996 by the BLM due to dry conditions resulting in plants retracted underground. No monitoring reports were submitted to the Service for the years 2010 and 2012.

Our knowledge of abundance and trend information was assessed from annual monitoring reports by the BLM (1986 to 2011) and Navajo Nation (2006 to 2011). Each agency has monitoring plans that are set up to track specific information in each of their populations. However, there are differences in data collection, and this inconsistency makes it difficult to compare trends across the landscape and ownerships. Therefore, results are presented for each landowner separately. No monitoring program has been established for the Fickeisen plains cactus on the Kaibab National Forest and the Cataract Ranch.

Trend information from the five monitored plots indicates that these populations have experienced significant declines in plant numbers. Plant numbers in the four BLM plots increased by approximately 98 percent from 1987 to 1992, but declined by 59.5 percent from 1993 to 2011 (Table 4). The reported decline is based on the number of tagged Fickeisen plains cactus that are present (emergent and alive) during the monitoring period. If an individual tagged plant is retracted underground during the monitoring period, it is counted as missing or retracted but is not included in the live plant count. If that plant does not emerge after 3 consecutive years, the BLM will mark the plant as dead. The Salt Trail Canyon plot on the Navajo Nation plot shows a 49 percent decline over the last 5 years. This decline is also based on the number of live, emergent plants counted during the monitoring period. Plants that are reportedly dead or missing are tallied separately in each successive year that monitoring occurs.

Bureau of Land Management Lands

—The BLM manages habitat for 13 documented Fickeisen plains cactus populations (Table 3) that occupy an estimated 36.9-ha (91.3-ac) area (BLM 2007b, p. 67) on the Arizona Strip. The total known population on the Arizona

Strip has declined from 323 individuals in 1991 to 127 individuals in 2011 (Table 4).

The Fickeisen plains cactus was first documented on the Arizona Strip in 1977 at Sunshine Ridge with the remaining populations discovered up through 1986 (Phillips 1979, entire; AGFD 2011b, entire). The populations are widely separated from one another (roughly 31 km (19 mi) apart) in geographically disjunct locations. In Mohave County, populations have been documented in Mainstreet Valley near Dutchman Draw, in Hurricane Valley near Toquer Tank, in Lower Hurricane Valley near Temple Trail, in Salaratus Draw in the Hurricane Cliffs, on Clayhole Ridge, and on Sunshine Ridge. Populations have also been documented in Coconino County near the canyon rims of Marble Canyon, South Canyon, and North Canyon Wash in House Rock Valley. Searches for the Fickeisen plains cactus after 1987 have not located any additional occurrences despite the abundance of suitable habitat present (Hughes 1996a, p. 47; Hughes 2011, pers. comm.).

In 1986, the BLM established long-term monitoring at the Dutchman Draw, North Canyon wash, Clayhole Ridge, and Sunshine Ridge populations (Hughes 1996a, p. 47). The plots were located in populations that contained the densest number of Fickeisen plains cacti and were easily accessible (Hughes 2009, p. 28; Hughes 2011, pers. comm.). They were visited each year from 1986 to 2009, and in 2011, to record information on abundance, size (diameter), reproduction, recruitment, mortality, and missing or retracted plants. BLM classified plants into five different size classes based on measured width between 1987 and 1995. After 1997, two size classes were used to reflect the juvenile (0 to 15 mm (0.6 in)) and adult (16 to 31 mm and greater (0.63 to 1.22 in)) size classes. The changes to the size classes prevents comparing the data among years; however, it does provide some information regarding the proportion of the population in the small and larger size classes that can be used to describe recruitment. Besides the four plots, BLM established seven cluster plots: Navajo, Ward, Salaratus Draw 1, Salaratus Draw 2, Sunshine Ridge 2, Temple Trail, and Toquer Tank. Cluster plots consist of rebar centered among a small number of scattered individuals. These are visited once every 5 to 10 years for the purpose of recording presence/absence.

Dutchman Draw—The Dutchman Draw plot is the largest plot, situated within tall, dense grass in Mainstreet Valley. It has experienced a 95 percent decline in the last 18 years. Up until 1999, plant numbers in the plot accounted for 64 to 74 percent of the total reported numbers for the Arizona Strip population. Abundance in this plot increased during the late 1980s from 167 individuals to a high of 219 plants in 1992. As of 2011, only 12 plants occur in the plot. The plot experienced its highest number of seedlings from 1989 to 1992, a period when the BLM recorded plants in the smallest size class. Only one other seedling was detected in 1994. Between 1997 and 2005, the two size classes were relatively equal. After 2007, the larger size class showed an upward trend, while a significant drop occurred in the smaller size class. This gap between the two size classes has continued through 2011, in which 83 percent of the plot's individuals are adult plants. There were a total of 111 plants counted as recruitment (plants with a diameter less than 20 mm (0.79 in)) with an average of 7 individuals per year; 94 percent of those were reported from 1994 to 2004. On average, 31 percent of tagged plants fruited in 5 of the 22 years of percent fruiting was recorded. From 2001 to 2011, 174 plants were reported missing or retracted (average 35 plants per year). Mortality totaled 257 plants over a 15-year period from 1987 to 2011 with 144 of those occurring in the year 2000. The BLM stated that the 144 mortalities included tagged plants that that were previously counted as retracted plants but because they had not been seen since the late nineties, they were assumed to be dead (Hughes 2000a, p. 2). In summary, this plot has shown a continued decline since 1992. Although many plants are within reproductive age, there have not been any significant increases in plant numbers. Mortality and the number of plants missing or retracted have been higher than the number of new recruits. With only 12 plants in 2011, we believe this plot could be extirpated in the near future.

Clayhole Ridge—The Clayhole Ridge plot occurs on top of a limestone ridge (BLM 2007b, p. 67). Plant numbers have varied with a high of 63 individuals (2001) and a low of 16 individuals (1998). Since 2001, plant numbers have declined by 33 percent. As of 2011, the plot has 42 plants. No seedlings were reported from 1987 to 1995, when the small size classes were measured. During that period, 76 percent of the individuals were greater than 20.1 mm (0.79 in) in diameter, while 9 percent were less than 10 mm (0.39 in) in diameter. The gap between the small and larger size classes has continued through 2011, with 88 percent of the individuals in the larger size class. Hughes (1996b, p. 17) attributed this division to the lack of intensive surveys for seedlings. This plot had the highest percent of cactus producing fruit and in the most years compared to the other plots. Fruiting production occurred in 16 of the 22 years reported with 6 to 85 percent of tagged cactus fruiting in any given year. New recruits, however, appeared to be low, with a total of 34 new plants (average of 2 per year) reported in 11 of the 16 years. There were a total of 40 mortalities between 1988 and 2005, and 251 plants were reported missing or retracted from 1998 to 2009 (average of 21 plants per year). In summary, abundance has varied in this plot overall. Since 2001, plant numbers have declined by 33 percent. Even with the high number of plants that produced fruit and considering that larger individuals produced multiple fruit, recruitment appears to be poor. Mortalities, in combination with the number of plants missing or retracted, are substantially high in light of overall plant numbers. The years between 2000 and 2001 are the exception, when plant numbers increased from 20 to 63. Reasons attributed for the sharp increase are unknown and do not appear to be correlated to weather, as the spring of 2000 was very dry (Hughes 2000a, p. 1).

Sunshine Ridge—The Sunshine Ridge plot is located along a ridgeline and downslope on a bench next to Toroweap Road (Hughes 1996b, p. 17). This plot has experienced great variations in plant numbers. Monitoring began with six plants in 1986, and as of 2011, the plot contained 34 plants. Plant numbers fluctuated from a high of 44 (1992) to none being observed in 2000, because they were either retracted or dead (Hughes 2000a, p. 1; Hughes 2005a, pers. comm.), possibly in response to below-average precipitation that year. The plot had two distinct periods of relatively high numbers; from 1990 to 1995, with an average of 35 plants, and from 2005 to 2011, with an average of 29 plants. The worst years occurred in between these peaks. The plot was vandalized in 1996, which may have contributed to the significant decline, although plants were not observed to have been damaged by the vandalism (Hughes 2005a, pers. comm.). From 1987 to 1995, 77 percent of individuals were greater than 10.1 mm (0.40 in) in diameter, while only two very small plants were discovered during this period. From 1997 through 2011, the majority of the plants were in the larger size class which currently includes 85 percent of the individuals in this plot.

Fruit production occurred in 10 of the 22 years, with 16 to 79 percent of tagged cacti fruiting. A total of 26 new recruits (average 1.7 per year) occurred in 7 of the 16 years reported. A total of 43 plants died, with 74 percent of those mortalities occurring from 1989 to 1995. There was also a total of 45 plants reported missing or retracted (average of 4 per year), with 82 percent of these reports occurring from 2006 to 2009. In summary, this plot has experienced great fluctuations in numbers but has maintained an average of 21 plants over the years. Reasons for the fluctuations have not been fully investigated. Despite a high percentage of plants fruiting, only two seedlings were documented over a 16-year period. Both mortality and the number of plants missing or retracted exceeds the number of new recruits. The status of the species in the plot appears to be unstable and trending towards decline.

North Canyon—The North Canyon Plot occurs in House Rock Valley on two small hills near North Canyon wash. As of 2011, the plot contained 39 plants. Plant numbers have also varied and have not been investigated. From 1987 to 1991, plant numbers increased by approximately 55 percent, then declined by approximately 81 percent in 1992. The sharp decline was attributed to a high number of plants lost from rodent predation in 1992. Post 1992, plant numbers have gradually increased to a high of 40 in 2004 and 2005, and currently fluctuate between 31 and 39 individuals. Size structure has been dominated by larger individuals since 2000; few to no seedlings have been reported. From 1988 to 1995, 85 percent of plants were greater than 10.1 mm (0.40 in) in diameter. No small-sized plants were found during these years. From 1997 through 2002, the size class distribution was relatively equal. After 2002, a shift occurred, with an increase in the number of individuals in the larger size class and a decrease in the number in the smaller size class. Currently, 90 percent of plants are in the larger size class. Fruit production occurred in 11 of the 22 years reported, with 8 to 64 percent of tagged cactus fruiting. There were 31 new recruits (average of 2 plants per year) in 10 of 16 years reported. There

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