Endangered and Threatened Wildlife and Plants; Removing Arenaria cumberlandensis (Cumberland Sandwort) From the Federal List of Endangered and Threatened Plants

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), propose to remove Cumberland sandwort (Arenaria cumberlandensis) from the Federal List of Endangered and Threatened Plants (List). We also announce the availability of a draft post-delisting monitoring (PDM) plan for the Cumberland sandwort. We seek information, data, and comments from the public on this proposed rule and on the associated draft PDM plan. If this proposal is finalized, the Cumberland sandwort will be removed from the List.

DATES:

We will accept comments received or postmarked on or before June 26, 2020. Comments submitted electronically using the Federal eRulemaking Portal (see ADDRESSES, 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 FOR FURTHER INFORMATION CONTACT by June 11, 2020.

ADDRESSES:

You may submit comments on this proposed rule and draft PDM plan by one of the following methods:

(1) Electronically: Go to the Federal eRulemaking Portal: http://www.regulations.gov. In the Search box, enter FWS-R4-ES-2019-0080, which is the docket number for this rulemaking. Then, click on the Search button. On the resulting page, in the Search panel on the left side of the screen, under the Document Type heading, click on the Proposed Rule box to locate this document. You may submit a comment by clicking on “Comment Now!”

(2) By hard copy: Submit by U.S. mail to: Public Comments Processing, Attn: FWS-R4-ES-2019-0080; U.S. Fish and Wildlife Service, MS: PRB/3W, 5275 Leesburg Pike, Falls Church, VA 22041-3803.

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 Public Comments, below, for more information).

Document availability: The proposed rule, draft PDM plan, and supporting documents are available at http://www.regulations.gov under Docket No. FWS-R4-ES-2019-0080.

FOR FURTHER INFORMATION CONTACT:

Lee Andrews, Field Supervisor, U.S. Fish and Wildlife Service, Tennessee Ecological Services Field Office, 446 Neal Street, Cookeville, Tennessee, 38501; telephone (931) 528-6481. Individuals who use a telecommunications device for the deaf (TDD), may call the Federal Relay Service at (800) 877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule. Under the Endangered Species Act of 1973, as amended (Act), we are required to conduct a review of all listed species at least once every 5 years (5-year review) to review their status and determine whether they should be classified differently or removed from listed status. In our 2013 5-year review for the Cumberland sandwort, we recommended reclassifying the species from endangered to threatened. We initiated another 5-year review for the species on May 7, 2018 (83 FR 20093), and determined the species met the criteria for delisting. Therefore, we are publishing this proposed rule to delist the species.

What this document does. This document proposes to remove the Cumberland sandwort from the List. It also announces the availability of a draft PDM plan for the Cumberland sandwort. This determination is based on a thorough review of the best available scientific and commercial data, which indicate that the Cumberland sandwort has recovered and no longer meets the definition of an endangered or a threatened species under the Act. Our review shows that threats to the species identified at the time of listing (i.e., timber harvesting, trampling from recreational uses, and digging for archaeological artifacts) have been reduced to the point that they no longer threaten the species, and the Cumberland sandwort has increased in abundance and range. Our review also indicates that potential effects of projected climate change are not expected to cause the species to become endangered in the foreseeable future.

The basis for our action. Under the Act, we may determine that a species is an endangered or threatened species because of one or more of the five factors described in section 4(a)(1) of the Act. We must consider the same factors in removing a species from the List (delisting) in determining whether a species meets the definition of an endangered species or a threatened species.

Here, we have determined that the Cumberland sandwort may be considered for delisting based on recovery. In the rule listing the Cumberland sandwort (53 FR 23745, June 23, 1988), the primary threats identified for the species were the destruction and modification of habitat (Factor A) due to trampling by recreational users of the rockhouse and bluff habitats where the species occurs, trampling and soil disturbance from looting of archeological artifacts (i.e., relic digging), and timber harvesting in or adjacent to occupied sites. While some habitats occupied by Cumberland sandwort are exposed to these potential stressors, many are protected from these activities, and available data support the determination that the species is more resilient to these threats than was assumed at the time of listing. The listing rule also discussed limited distribution and small population size (Factor E), along with inadequate regulatory mechanisms for preventing habitat destruction (Factor D), as factors contributing to the species' endangerment. However, our review of the status of and listing factors for the Cumberland sandwort indicated: (1) An increase in the number of occurrences of the species within its geographically restricted range and increased abundance in some occurrences; (2) resiliency to existing and potential threats; (3) the protection of 66 extant occurrences located on Federal and State conservation lands by regulations or management plans to prevent habitat destruction or removal of plants; and (4) the implementation of beneficial management practices. Accordingly, the Cumberland sandwort no longer meets the definition of an endangered or threatened species under the Act.

Peer review. We are requesting comments from independent specialists to ensure that we base our determination on scientifically sound data, assumptions, and analyses.

Information Requested

Public Comments

We want any final rule resulting from this proposal to be as accurate and effective as possible. Therefore, we invite tribal and governmental agencies, the scientific community, industry, and other interested parties to submit data, comments, and new information concerning this proposed rule. The comments that will be most useful and likely to influence our decision are those that are supported by data or peer-reviewed studies and those that include citations to, and analyses of, applicable laws and regulations. Please make your comments as specific as possible and explain the basis for them. In addition, please include sufficient information with your comments to allow us to authenticate any scientific or commercial data you reference or provide. In particular, we are seeking comments on:

(1) Biological data regarding the Cumberland sandwort, including the locations of any additional occurrences, survey data, or other relevant information;

(2) Relevant data concerning any threats (or lack thereof) to the Cumberland sandwort;

(3) Additional information regarding the range, distribution, life history, ecology, and habitat of the Cumberland sandwort;

(4) Current or planned activities within the geographic range of the Cumberland sandwort that may negatively impact or benefit the Cumberland sandwort; and

(5) The draft PDM plan and the methods and approach detailed in it.

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.”

In developing a final determination on this proposed action, we will take into consideration all comments and any additional information we receive. Such information may lead to a final rule that differs from this proposal. All comments and recommendations, including names and addresses, will become part of the administrative record.

You may submit your comments and materials concerning the proposed rule by one of the methods listed in ADDRESSES. We request that you send comments only by the methods described in ADDRESSES.

We will post your entire comment—including your personal identifying information—on http://www.regulations.gov. If you provide personal identifying information in your comment, you may request at the top of your document that we withhold this information from public review. However, we cannot guarantee that we will be able to do so.

Comments and materials we receive, as well as supporting documentation we used in preparing this proposed rule, will be available for public inspection on http://www.regulations.gov.

Public Hearing

Section 4(b)(5)(E) of the Act provides for one or more public hearings on this proposal, if requested. We must receive requests for a public hearing, in writing, at the address shown in FOR FURTHER INFORMATION CONTACT by the date shown in DATES. We will schedule a public hearing on this proposal, if requested, and announce the date, time, and place of the hearing, as well as how to obtain reasonable accommodations, in the Federal Register at least 15 days before the hearing.

Peer Review

In accordance with our policy published in the Federal Register on July 1, 1994 (59 FR 34270), and our August 22, 2016, memorandum updating and clarifying the role of peer review of listing actions under the Act, we will solicit the expert opinions of at least three appropriate and independent specialists regarding the science in this proposed rule and the draft PDM plan. The purpose of such review is to ensure that we base our decisions on scientifically sound data, assumptions, and analyses. The peer reviewers will be selected based upon their expertise in the Cumberland sandwort's biology, habitat, and physical or biological factors that will inform our determination. We will send peer reviewers copies of this proposed rule and the draft PDM plan immediately following publication of this proposed rule in the Federal Register. We will invite them to comment, during the public comment period, on the specific assumptions and conclusions regarding this proposed delisting rule and the associated draft PDM plan. We will summarize the opinions of these reviewers in the final decision documents, and we will consider their input and any additional information we receive as part of our process of making a final decision on this proposal and draft PDM plan. Such communication may lead to a final decision that differs from this proposal.

Previous Federal Actions

On June 23, 1988, we listed the Cumberland sandwort as endangered, due to the threat of habitat destruction or modification resulting from unintended trampling by recreational users of public lands, unauthorized digging of Native American artifacts, and timber harvesting, combined with the low number of occurrences known to exist at the time of listing and low abundance at most occurrences (53 FR 23745). On June 20, 1996, we released a recovery plan for the Cumberland sandwort (Service 1996). We completed another 5-year review for the Cumberland sandwort on December 23, 2013. This 5-year review summarized all new information accumulated on the species since the publication of the species' recovery plan and recommended reclassification to threatened status. We initiated a third 5-year review for the species on May 7, 2018 (83 FR 20093), and, based on our review of available data we gathered during preparation of that 5-year review, and presented herein, we have determined that the recovery criteria for delisting the species have been met. This rule will, therefore, equate to our 5-year review. We are providing the 2013 5-year review as a supplemental document to the proposed rule at https://www.regulations.gov at (Docket No. FWS-R4-ES-2019-0080) or https://www.fws.gov/southeast/endangered-species-act/five-year-reviews/.

For additional details on previous Federal actions, including recovery actions, see discussion under the Recovery section of the preamble, below.

Species Information

Below, we present a thorough review of the taxonomy, life history, ecology, and overall status of this plant, referencing data from the 2013 5-year review (Service 2013) where appropriate.

Taxonomy

Cumberland sandwort (Arenaria cumberlandensis), a member of the Pink family (Caryophyllaceae), was first recognized and described as a species in 1979 (Wofford and Kral 1979, entire). This species, along with several other species of Arenaria, was transferred to the genus Minuartia while retaining the specific epithet (McNeill 1980, entire). The species is listed as Minuartia cumberlandensis (Wofford and Kral) McNeill in A Fifth Checklist of Tennessee Vascular Plants (Chester et al. 2009, p. 43), the Integrated Taxonomic Information System (ITIS) (2019), and Flora of North America (2019). However, an examination of the taxonomy of Minuartia using DNA sequences determined that all species in Minuartia section Uninerviae should be elevated to genus Mononeuria, along with Geocarpon minimum (Dillenberger and Kadereit 2014, p. 79). The Flora of the Southern and Mid-Atlantic States accepted this recommendation, assigning the name Mononeuria cumberlandensis (B.E. Wofford & Kral) Dillenberger & Kadereit to Cumberland sandwort (Weakley 2015, p. 820). Although there have been changes to the species' taxonomy since the time of listing, we are proposing to remove the species from the List of Endangered and Threatened Plants using the name by which it was initially listed, Arenaria cumberlandensis (=Mononeuria cumberlandensis).

Population Genetics

In a study of populations in Tennessee, Cumberland sandwort was found to possess “fairly high” levels of genetic variation (Winder 2004, pp. 16-19). Observed levels of heterozygosity were consistent with expected effects of frequent mating among closely related individuals, or inbreeding (Winder 2004, p. 19), a common phenomenon in small populations due to the greater likelihood that most or all individuals in the population will be closely related (Allendorf and Luikart 2007, p. 306). Greater genetic similarity was found among populations within about 4 kilometers (km) (2.5 miles (mi)) of one another, but a wide range of values were observed at distances of 4 to 25 kilometers (2.5 to 15.5 mi), beyond which populations were consistently dissimilar (Winder 2004, p. 27). Thus, Cumberland sandwort populations generally are genetically independent of one another and have been for a significant period of time, with possible exceptions where gene flow could occur among densely clustered populations in close geographic proximity to one another (Winder 2004, p. 28). The majority of the genetic variation found in the species is retained within a central cluster of populations located in Pickett County, Tennessee, and in Laurel Fork (Fentress County) (Winder 2004, p. 37). The genetic structure of the lone Kentucky population and its relation to sites sampled in Tennessee are unknown.

Species Description

The following description of Cumberland sandwort is modified from Wofford and Kral (1979, pp. 257-259) and Kral (1983, pp. 363-364). This species is a delicate perennial that occurs in small cushionlike clumps, with upright stems 10 to 15 centimeters (cm) (4 to 6 inches (in)) tall that are slender and triangular in shape. Leaves are opposite, 2 to 3 cm (0.8 to 1.2 in) long and 1 to 3 millimeters (mm) (0.04 to 0.12 in) wide, and are thin and bright green in color, with glassy margins. Basal leaves are longer and wider than those at the top of the stems. The flowers are symmetrical, five-parted, and usually solitary at the end of the stems. The sepals (a part of the flower that provides protection for the flower in bud and sometimes provides support for petals when in bloom) are green and inconspicuously three-veined, and the white petals usually have five green veins. The fruit is a 3- to 3.5-mm-long (0.12 to 0.14 in) ovoid capsule containing numerous reddish-brown reticulated (having the form or appearance of a net) seeds that are 0.5 to 0.7 mm (0.02 to 0.03 inches) long.

The mild conditions of the sheltered habitat where Cumberland sandwort occurs allow rosettes (circular arrangement of leaves) to persist through winter and produce abundant, leafy stems in the spring (Winder 2004, p. 5). The species flowers from May through August, with some flowers persisting as late as November (Wofford and Kral 1979, p. 259; Winder 2004, p. 5).

Habitat

Cumberland sandwort inhabits fine-grained, sandy soils that comprise the floors of the interior of “rockhouses” (cave-like recesses produced by differential weathering of sandstone). These habitats are typically behind the dripline of overlying cliffs, ledges, and solution pockets of cliffs, where these features are found in Pennsylvanian sandstones on the Cumberland Plateau in southern Kentucky and northern Tennessee (Horton 2017, entire). The species occupies sites that generally share characteristics of high levels of shade, moisture, and humidity, and relatively constant, cool temperatures (Wofford and Smith 1980, p. 7), although some smaller occurrences occupy drier and warmer sites. Few other species are directly associated with Cumberland sandwort microsites, but the following species are important indicators that suitable habitat conditions are present within a given rockhouse or bluff site: Silene rotundifolia (round-leaved catchfly), Thalictrum clavatum (mountain meadow-rue), Heuchera parviflora (little-flowered alumroot), Ageratina lucae-braunae (Lucy Braun's snakeroot), Stenanthium diffusum (diffuse reather-bells) and the bryophytes Vittaria appalachiana (Appalachian shoestring fern), Bryoxiphium norvegicum (Norway bryoxiphium moss), and Scopelophila cataractae (cataract scopelophila moss) (TDEC 2011b, p. 5).

Distribution

When Cumberland sandwort was listed as endangered, the species was known from 11 occurrences (Wofford and Smith 1980, pp. 9-18), which were treated as 5 populations (53 FR 23745, June 23, 1988). Of these occurrences, 1 was in McCreary County, Kentucky, and 10 were distributed among four Tennessee counties (Fentress, Morgan, Pickett, and Scott). The species recovery plan (Service 1996, pp. 6-8) reported that 28 occurrences were extant, including the 11 from the listing rule, 27 of which were partly or entirely located on publicly owned conservation lands. One of these 28 occurrences was in McCreary County, Kentucky, and the remaining 27 were distributed among the 4 Tennessee counties reported in the listing rule. All occurrences reported in the listing rule and species recovery plan were located in the South Fork Cumberland River drainage. Of these 28 occurrences, all but 3 were extant as of 2017 (TNHID 2018).

As explained below, documentation to verify past or present existence is lacking for two of the three occurrences we did not determine to be extant as of 2017, raising questions regarding their validity. The “Middle Creek 2” occurrence reported in the recovery plan was apparently based on an observation reported by a National Park Service (NPS) archaeologist, but staff of the TDEC Division of Natural Areas (TDNA) were unable to confirm the presence of Cumberland sandwort at the mapped location, which they attribute to a mapping error when the occurrence was reported. The Morgan County occurrence reported in the recovery plan, with only the site name “Sunbright” given for location information, also cannot be verified. No citation was provided in the recovery plan for this record, and no record existed for this site in the Tennessee Natural Heritage Inventory Database (TNHID) (2018), maintained by the Natural Heritage Program at TDNA. A search of herbarium records for Cumberland sandwort from Morgan County, Tennessee, produced no specimens from the vicinity of Sunbright (SERNEC Data Portal 2018). However, a new extant occurrence record was documented in TNHID for Scott County, based on the label for a specimen collected in 2002 from a site not previously known to be occupied by Cumberland sandwort.

The Big Branch occurrence reported in the recovery plan was not recorded in the TNHID (2018), so no attempts have been made to relocate this occurrence. Staff from NPS reported the occurrence in comments provided after reviewing the draft recovery plan (NPS 1995). We provided information to TDNA on the Big Branch occurrence reported by NPS, and there is now a historical record for this occurrence in the TNHID.

In order to evaluate the current status of Cumberland sandwort, we used data from Natural Heritage Programs in Kentucky (KNHP 2018) and Tennessee (TNHID 2018) to determine the location and condition of mapped element occurrences. An element occurrence (E.O.) is a fundamental unit of information in the NatureServe Natural Heritage methodology, and is defined as “an area of land and/or water in which a species . . . is, or was present” (NatureServe 2004). There were 64 extant occurrences of Cumberland sandwort reported in the 2013 5-year review. As of 2018, there were 71 extant occurrences, distributed among the 5 counties where the species was reported to be extant when the recovery plan was published: 1 in McCreary County, Kentucky (Kentucky Natural Heritage Program (KNHP) 2018); 1 in Morgan, 26 in Fentress, 38 in Pickett, and 5 in Scott Counties, Tennessee (TNHID 2018). Of these occurrences, 12 occur within the Obey River drainage in Tennessee; 11 of these occurrences have been discovered since 2005 on recently acquired, State-owned conservation lands, and 1 on privately owned lands in 2016. The remaining 59 occurrences lie within the South Fork Cumberland River drainage, and all but 1 in Tennessee. Four of the occurrences in the South Fork Cumberland River drainage are located on privately owned lands in Tennessee; the remainder are located on state or federal conservation lands. In addition to these 71 natural occurrences of Cumberland sandwort, one introduced occurrence has been established in McCreary County, Kentucky, on the Daniel Boone National Forest (DBNF) (Pence et al. 2011, entire).

Framework for Monitoring and Evaluating Trends

The TDEC Natural Heritage Program began monitoring Cumberland sandwort in Tennessee during 2000, estimating abundance in 34 sites as part of a project to conduct surveys for new locations and update records for previously known occurrences of the species (TDEC 2000, entire). The number of occurrences monitored has increased to 55, and TDEC has categorized sites into three tiers of differing priority, with highest priority sites to be most frequently monitored (TDEC 2007, p. 5):

• Tier 1 sites have a history of site disturbance related to recreational use or illicit digging of Native American artifacts.
• Tier 2 sites face fewer immediate threats in the less frequently visited sites they occupy.
• Tier 3 sites faced no imminent threats at the time of categorization.

Designating tiers provides for more frequent monitoring of sites with a greater likelihood of being adversely affected by known threats that could warrant management intervention. Tier 1 sites are monitored every 1 to 3 years, Tier 2 sites every 3 to 6 years, and Tier 3 sites every 6 to 10 years (TDEC 2007, p. 5). In addition to monitoring during 2000 and 2006 (before the tier system was developed), TDEC monitored Tier 1 sites during 2010 and 2011 (TDEC 2011a, entire), 2014 (TDEC 2014, entire), and 2017 (TDEC unpublished data). Tier 2 sites were monitored during 2011 through 2012 (TDEC 2012, entire), and Tier 3 sites were monitored during 2016 and 2017 (TDEC unpublished data).

The Service receives monitoring data in the form of written reports and occurrence-level summary data provided in the TNHID (2018). We used these summary data to determine which sites in each tier had been monitored in two or more years, making it possible to assess whether Cumberland sandwort had declined, remained stable, or increased either in estimated abundance or area occupied. Based on data provided in the TNHID, 18 occurrences are in Tier 1, 24 in Tier 2, and 13 in Tier 3 for which such data were available. Tier 1 occurrences have been monitored an average of 4.7 times, with time between initial and the most recent monitoring events averaging 15.8 years. Tier 2 occurrences have been monitored an average of 2.4 times over an average timespan of 8.4 years. Tier 3 occurrences have been monitored an average of 2.4 times over an average timespan of 12.1 years. Fifteen occurrences in Tennessee have been monitored only once or have not, as yet, been assigned to a monitoring tier.

After reviewing all available monitoring data, TDEC assessed whether individual occurrences had declined, remained stable, or increased over the time that they have been monitored (McCoy 2018, pers. comm.). However, statistical trend analysis of Cumberland sandwort monitoring data from Tennessee is not feasible for two reasons: First, estimates of abundance generated in 2000 and in later monitoring events lack adequate precision for statistically analyzing change in abundance over time, and second, visual estimates of area occupied by the species can introduce potential for observer bias because these areas are not precisely measured. However, the preparation of hand-drawn maps by TDEC botanists, beginning with the initial monitoring effort in 2000, allows tracking persistence and stability of individual patches within occupied sites and detecting substantial changes in their estimated size. Based on the best available data, of the 18 Tier 1 occurrences, 2 demonstrate evidence of decline, 13 are stable, and 3 have increased. Of the 24 Tier 2 occurrences that have been monitored on two or more occassions, 5 demonstrate evidence of decline, 18 are stable, and 1 has increased. Of the 13 Tier 3 occurrences, 2 have declined, 10 are stable, and 1 has increased (McCoy 2018, pers. comm.).

Recovery

Section 4(f) of the Act directs us to develop and implement recovery plans for the conservation and survival of threatened and endangered species unless we determine that such a plan will not promote the conservation of the species. Recovery plans are not regulatory documents and are instead intended to: (1) Establish goals for long-term conservation of a listed species; (2) define criteria that are designed to indicate when the threats facing a species have been removed or reduced to such an extent that the species may no longer need the protections of the Act; and (3) provide guidance to our Federal, State, and other governmental and non-governmental partners on methods to minimize threats to listed species. There are many paths to accomplishing recovery of a species, and recovery may be achieved without all criteria being fully met. For example, one or more criteria may have been exceeded while other criteria may not have been accomplished, yet the Service may judge that, overall, the threats have been minimized sufficiently, and the species is robust enough, to reclassify the species from endangered to threatened or perhaps delist the species. In other cases, recovery opportunities may have been recognized that were not known at the time the recovery plan was finalized. These opportunities may be used instead of methods identified in the recovery plan.

Likewise, information on the species may be learned that was not known at the time the recovery plan was finalized. The new information may change the extent that criteria need to be met for recognizing recovery of the species. In short, recovery of species is a dynamic process requiring adaptive management that may, or may not, fully follow the guidance provided in a recovery plan.

The Cumberland Sandwort Recovery Plan (see Previous Federal Actions, above) included recovery criteria to indicate when threats to the species have been adequately addressed and prescribed actions that were thought to be necessary for achieving those criteria. Below we discuss our analysis of available data and our determination as to whether recovery criteria for Cumberland sandwort have been achieved.

Recovery Criteria

The objective of the recovery plan is to delist the Cumberland sandwort. Recovery criteria in the plan state that Arenaria cumberlandensis (Cumberland sandwort) will be considered for reclassification from endangered to threatened status when 30 geographically distinct, self-sustaining occurrences are protected in four counties in Tennessee and Kentucky and have maintained stable or increasing numbers for 5 consecutive years. The species will be considered for delisting when 40 geographically distinct, self-sustaining occurrences are protected and have maintained statistically stable or increasing numbers for 5 consecutive years. At least 12 of these occurrences must be in counties other than Pickett County, Tennessee.

Methods were chosen for monitoring that minimize trampling of Cumberland sandwort and disturbance of the sandy soil substrate the species occupies. The tradeoff of using this method to minimize disturbance is the inability to statistically analyze trends for individual occurrences or Cumberland sandwort as a species. To address this limitation, we developed a framework for using available distribution and monitoring data, aerial photography, and qualitative assessment of trends for each occurrence to evaluate whether recovery criteria for Cumberland sandwort have been achieved.

Using this framework we assessed the species' viability based on the three conservation biology principles of resiliency, representation, and redundancy (Shaffer and Stein 2000, entire). Resiliency is the ability to sustain populations in the face of environmental variation and transient perturbations. To be resilient, a species must have healthy populations that are able to sustain themselves through good and bad years. The greater the number of healthier populations, the more resiliency a species possesses. Representation is the range of variation or adaptive diversity found in a species, and is the source of a species' ability to adapt to near- and long-term changes in the environment. Maintaining adaptive diversity requires conserving both ecological and genetic diversity, which enable a species to be more responsive and adaptive to change and, therefore, more viable. Finally, redundancy protects species against the unpredictable and highly consequential events for which adaptation is unlikely, allowing them to withstand catastrophic events. Redundancy spreads risk and is best achieved by having multiple populations widely distributed across a species' range.

We characterized the resiliency of 69 of the 71 extant Cumberland sandwort occurrences using available data on three factors (complete data were not available for two of the extant occurrences): Occurrence size expressed as estimated abundance or areal coverage, recorded observations of threats causing disturbance to plants or the substrates in which they were rooted, and assessment of general forest conditions from recorded observations or evaluation of aerial photography, for the reasons that follow. Smaller populations are at greater risk of (1) losing genetic variation due to drift (change in the frequency of alleles in a population due to random, stochastic events), and (2) inbreeding, which decreases the likelihood that an individual will receive pollen from a compatible mate and produce viable offspring (Allendorf and Luikart 2007, pp. 122-123). Small populations also may face higher risks of extinction due to diminished resilience to demographic and environmental stochasticity (Münzbergová 2006, p. 143). Demographic stochasticity is the variation in vital rates (i.e., probabilities of survival and reproduction) among individuals of a given age or life-cycle stage, at a given point in time, while environmental stochasticity is variation in vital rates over time, affecting all individuals of a given age or stage similarly (Lande 1988, p. 1457). Undisturbed substrates contribute to Cumberland sandwort resiliency by providing suitable sites for germination, growth, and reproduction to occur. Also, the presence of contiguous forest vegetation in the vicinity of Cumberland sandwort occurrences helps to maintain suitable hydrology and microclimate, potentially buffering severity of stress resulting from environmental perturbations, such as drought. We evaluated representation by considering the distribution of resilient occurrences among the counties and watersheds from which the species is known. Finally, we evaluated redundancy based on the overall number of resilient occurrences distributed throughout its range.

In evaluating resiliency, we used estimates of abundance, where available, combined with estimates of areal coverage to provide a basis for categorizing occurrences into groups of low, medium, or high abundance. Occurrences with fewer than 100 individuals (Heschel and Page 1995, pp. 128-131; Münzbergová 2006, p. 148) or with areal coverage less than 1 m² were ranked “low”; occurrences with 100-1,000 individuals or with areal coverage ranging from 1 to 5 m² were ranked “medium”; and occurrences with more than 1,000 individuals or areal coverage greater than 5 m² were ranked “high”. We ranked substrate conditions at each occurrence based on recorded observations of threats (TDEC 2011b, pp. 37-44). Substrate conditions were ranked “high” for sites with no record of disturbance; “medium” for sites with moderate risk of exposure to the threat based on limited historical evidence of digging for archeological artifacts (i.e., relic digging) or trampling by humans or wildlife in limited areas within available habitat; and “low” for sites with high risk of exposure as indicated by recent evidence of relic digging or trampling throughout available habitat. We used aerial imagery available through Google Earth Pro^TM to determine whether forests in the general vicinity of Cumberland sandwort occurrences exhibited signs of timber harvest, as indicated by substantially reduced tree densities, presence of logging equipment trails, or conversion to non-native, evergreen forest types. Forest conditions were ranked “high” in locations where late seral forest was present upslope and downslope of occupied sites and in adjacent areas; “medium” in locations where risk of exposure to the threat was moderate based on evidence of logging having occurred within the prior 15 years in the vicinity of, but not immediately upslope, downslope, or adjacent to, occurrences; and “low” in sites where risk of exposure was high based on evidence of logging within the prior 15 years in the forest immediately surrounding the occupied habitat.

Of the 69 occurrences that we could evaluate for all 3 resiliency factors, 12 were ranked as low in abundance, 27 ranked medium, and 30 occurrences ranked high. Substrate conditions ranked low at 12, medium at 25, and high at 32 occurrences. We were able to evaluate forest conditions at all 71 extant occurrences, with the following results: 8 occurrences ranked low, 3 ranked medium, and 60 ranked high.

Using the ranks for the 3 resiliency factors (abundance, substrate condition, and forest condition), we calculated an overall resiliency index for 68 of the 70 Tennessee occurrences (table 1) and the lone Kentucky occurrence. We assigned numerical scores of one for factor ranks of “low,” two for “medium” ranks, and three for “high” ranks. Using these scores, we calculated a weighted average, wherein factor ranks for abundance were given twice the weight of factor ranks for substrate and forest condition, due to the importance of population size in maintaining genetic variation and determining resilience to demographic and environmental stochasticity (Sgrò et al. 2011, p. 329). The resulting resiliency index for an occurrence ranges from one to three and is categorized as follows:

• Low rank for scores of 1.5 or less;
• Low-medium rank for scores greater than 1.5 and less than 2.0;
• Medium rank for scores ranging from 2.0 to 2.5;
• Medium-high rank for scores greater than 2.5 and less than 3.0;
• High rank for scores of 3.0.

Available data for the Kentucky occurrence indicate that the species abundance rank is medium at that location and that the occurrence is not exposed to threats from trampling or relic digging. This location, in BSF, is protected from timber harvesting, and available data indicate that surrounding forests are undisturbed. These factors produced an overall resiliency rank of medium for this occurrence.

In Tennessee, 56 occurrences had overall resiliency ranks of medium or higher. Table 1 shows the resiliency ranks for all Tennessee occurrences. All of the stable and increasing trends in the medium, medium-high, and high resiliency ranks represent counts of occurrences considered self-sustaining, as required by recovery criteria.

For the purpose of evaluating Cumberland sandwort's status with respect to recovery criteria, we define self-sustaining to include those populations that had an overall resiliency index rank of medium or higher and that TDEC determined were stable or increasing (Table 1) based on available monitoring data, as described above in Species Information. For the Kentucky occurrence, available data indicate that the occurrence is stable. We consider 66 occurrences on Federal or State conservation lands (Table 2), as well as 2 occurrences located on private lands where land use is restricted by conservation easements, to be protected. Using these definitions, 42 protected occurrences (including the 1 in Kentucky) are self-sustaining (table 1 presents data for Tennessee). These occurrences have been known to exist for an average of 21 years, with a range of 7 to 44 years spanning the first and most recent observations recorded for the species in these sites. This exceeds one criterion for removing Cumberland sandwort from the List—i.e., that there be at least 40 geographically distinct, protected, and self-sustaining occurrences that have been stable or increasing for at least 5 years.

The recovery criteria in the recovery plan also require that at least 12 of the protected, self-sustaining occurrences be located outside of Pickett County, Tennessee, presumably for the purpose of increasing representation and redundancy within the species' geographic range. Of the 42 occurrences meeting the criterion of being protected and self-sustaining, 28 are located in Pickett County, Tennessee, 13 are located elsewhere in Tennessee (9 in Fentress County, 4 in Scott County), and 1 is located in McCreary County, Kentucky. Thus, this delisting criterion is also exceeded.

Another measure of representation for the species is its distribution among major watersheds in which it is found. The recovery plan reported in 1996 that the species was known only from the South Fork Cumberland watershed, but it is now also known from 12 occurrences in the Obey River watershed in Tennessee. Of the 42 occurrences meeting the recovery criterion that there be at least 40 geographically distinct, protected, and self-sustaining occurrences, 2 are located in the Obey River watershed. The low number of occurrences in this watershed meeting this criterion is primarily due to the recent discovery of any occurrences in this watershed and consequent lack of repeat observations. In addition to the two occurrences in the Obey River watershed meeting the recovery criterion above, nine occurrences on protected lands have resiliency indices of medium or higher, and we expect that they will be self-sustaining and contribute to the species representation of resilient occurrences into the foreseeable future.

Our assessment of the viability of Cumberland sandwort supports the determination that the recovery criteria for delisting the species have been satisfied. The discussion above demonstrates that there are more than 40 protected and self-sustaining occurrences of the species, distributed among 4 counties in Tennessee and 1 in Kentucky.

Summary of Factors Affecting the Species

Section 4 of the Act and its implementing regulations (50 CFR part 424) set forth the procedures for listing species, reclassifying species, or removing species from listed status. We may determine that a species is an endangered or threatened species due to one or more of the five factors described in section 4(a)(1) of the Act: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) overutilization for commercial, recreational, scientific, or educational purposes; (C) disease or predation; (D) the inadequacy of existing regulatory mechanisms; or (E) other natural or manmade factors affecting its continued existence.

A recovered species is one that no longer meets the Act's definition of endangered or threatened. Determining whether the status of a species has improved to the point that it can be delisted or downlisted requires consideration of the same five factors identified above for listing a species. When Cumberland sandwort was listed as endangered in 1988, the identified threats (factors) influencing its status were the modification and loss of habitat and curtailment of range (Factor A), the inadequacy of State or Federal mechanisms to protect its habitat at that time (Factor D), and its limited distribution and low abundance in some populations (Factor E). The following analysis evaluates these previously identified threats, any other threats currently facing the species, as well as any other threats that are reasonably likely to affect the species in the foreseeable future following the delisting and the removal of the Act's protections.

The Act does not define the term “foreseeable future.” However, our implementing regulations at 50 CFR 424.11(d) (84 FR 45020) codify that the term “foreseeable future” extends only so far into the future as the Service can reasonably determine that the conditions potentially posing a danger of extinction in the foreseeable future are probable. The Service will describe the foreseeable future on a case-by-case basis, using the best available data and taking into account considerations such as the species' life-history characteristics, threat-projection timeframes, and environmental variability. The Service need not identify the foreseeable future in terms of a specific period of time, but may instead explain the extent to which we can reasonably determine that both the future threats and the species' responses to those threats are probable. To establish the foreseeable future for the purpose of determining whether Cumberland sandwort meets the definition of a threatened or endangered species, we evaluated trends from historical data on distribution and abundance, ongoing conservation efforts, factors currently affecting the species, and predictions of future climate change. Structured monitoring of Cumberland sandwort populations began in 2000, but records of initial observations for occurrences range from 1973 to 2017, with an average of 18 years between the earliest and most recent recorded observations for a given occurrence. The period of observation is 30 or more years for 16 occurrences, which vary in population size and threat exposure. These historical data provide insight into Cumberland sandwort's exposure and response to potential threats under varying conditions. When combined with our knowledge of factors affecting the species, available data allow us to reasonably predict future conditions, albeit with diminishing precision over time. Given our understanding of the best available data, for the purposes of this rule we consider the foreseeable future for Cumberland sandwort to be approximately 30 years.

In assessing threats to Cumberland sandwort, we consider the exposure of individual occurrences to suspected stressors, available data on the species response to those stressors where they have been observed, and efforts undertaken to reduce exposure into the future. As noted above in Recovery Criteria, available data indicate that the lone Kentucky occurrence is not exposed to threats that would result in modification or destruction of habitat.

Habitat Loss and Curtailment of Range

In the rule listing the Cumberland sandwort (53 FR 23745, June 23, 1988), the primary threats identified for the species were the destruction and modification of habitat due to trampling by recreational users of the rockhouse and bluff habitats where the species occurs, trampling and soil disturbance from looting of archeological artifacts (i.e., relic digging), and timber harvesting in or adjacent to occupied sites.

In Tennessee, the potential for trampling or soil disturbance from recreational use, wildlife, or relic digging has been noted at 38 sites where Cumberland sandwort occurs, with varying degrees of exposure and actual risk for adversely affecting the species (TDEC 2011b, pp. 40-44, TNHID 2018). In one of these sites (EO 78), signs of trampling and a fire pit were observed on the rockhouse floor in 2007 (TNHID 2018), but Cumberland sandwort plants are located on ledges and solution pockets on the bluff where they are not exposed to trampling. Additionally, no fire pit was observed during a site visit by the Service in February 2019. Of the other 37 sites where risk of trampling or soil disturbance has been recorded during monitoring or other site visits, available data indicate that Cumberland sandwort faces high risk of exposure in 12 of them and moderate risk in the other 25. Cumberland sandwort abundance has declined at 6 of the 12 sites with high exposure risk, while 5 have remained stable. Trend data are not available for the twelfth site, which was discovered in 2014. Declines in abundance have been observed at only three of the sites with moderate risk of exposure, while increases have been observed at three others. The remaining 19 sites with moderate risk of exposure to the threat of trampling or soil disturbance have remained stable. Thus, while the potential threat of trampling or soil disturbance has been noted at many sites, Cumberland sandwort faces a high risk of actual exposure in less than 20 percent of occurrences. Under conditions of moderate exposure risk, the species has demonstrated low vulnerability to being adversely affected, having maintained stable populations in most instances.

Protective features, including fences, boardwalks, barricades, rerouted trails, and/or informational signs have been installed at 8 of the 37 occurrences discussed above, protecting specific habitats occupied by Cumberland sandwort. (Service 2013, pp. 13-14, TDEC 2016, p. 3). The seven occurrences at PCNA are protected from recreational activities by the State's efforts to survey proposed alignments for new trails and route them away from sites with Cumberland sandwort. Measures such as these reduce or preclude the species' exposure to the threat of trampling from recreationists using trails on public lands where the species occurs.

Timber harvest occurs at PSF, but does not occur at BSF, PSP, or PCNA, limiting the potential magnitude of this activity, assumed to be a threat to Cumberland sandwort, to less than half of the sites on conservation lands. During the course of evaluating forest conditions in the vicinity of Cumberland sandwort occurrences, we observed that timber harvests had been conducted in the general vicinity of 10 occurrences at PSF, during the period between approximately 2008 and 2017. Timber harvests occurred upslope or downslope of seven of these occurrences, creating a high risk for exposure to potential effects of this threat, and in the general vicinity of three occurrences, where exposure risk was moderate. Sometime prior to 1999, the forest was converted to pasture on the plateau top above an eleventh occurrence, located on privately owned lands. Based on these data, timber harvests or forest conversion to pasture have taken place near approximately 15 percent of Cumberland sandwort sites. Data were available to evaluate trends for 10 of these 11 occurrences—3 have declined and 7 have remained stable. Monitoring data collected by TDEC at three of these occurrences since 2016 revealed no adverse effects from logging activities. These data support the conclusion that timber harvests in the vicinity of Cumberland sandwort occurrences that do not directly impact the species or its habitat may pose little threat in terms of indirect effects. This conclusion is also supported by observations from visits we conducted in February 2019 to four occurrences with nearby timber harvests, in which no adverse effects from off-site timber removal were detectable. Based on these observations, we conclude that our estimates of forest condition ranks, discussed above in Recovery Criteria, likely underestimate the resiliency of occurrences in those instances where forest condition ranks were reduced due to evidence of nearby logging activities.

While some Cumberland sandwort occurrences are exposed to potential habitat-related stressors that might, in certain situations, adversely affect the species, available monitoring data indicate that the species is less vulnerable to these threats than was assumed at the time of listing. In the event Cumberland sandwort is removed from the List, our draft post-delisting monitoring plan (see Post-delisting Monitoring, below) identifies 50 occurrences to be monitored over a period of at least 5 years following delisting, including 27 occurrences where risks of exposure to soil disturbance or trampling, effects of nearby timber harvests, or the two combined have been moderate to high. Continuing to monitor sites where Cumberland sandwort is exposed to potential threats that were previously assumed to place the species at risk of extinction will provide an opportunity to work with land managers to avoid or minimize adverse effects should the threats increase in severity or extent.

In our analysis of Cumberland sandwort's resiliency, discussed above in Recovery Criteria, we incorporated available data regarding threats that could potentially modify habitat or curtail the species' range. We determined that 42 occurrences currently meet the criterion of being protected and self-sustaining. These occurrences have been known to exist for an average of 21 years, with a range of 7 to 44 years spanning the first and most recent observations recorded for the species in these sites. In addition to these 42 occurrences, 9 occurrences are protected in the Obey River watershed and 2 in the South Fork Cumberland watershed in Tennessee for which sufficient monitoring data for evaluating trends in abundance or threats is lacking. However, seven of these occurrences in the Obey River drainage have no evidence of substrate or forest disturbance, and are located in PCNA, where TDEC (no date, pp. 10-11) surveys potential trail routes to prevent new trail construction that would expose occurrences to threats from recreational uses. No other potential threats to the habitats at PCNA have been documented. The two occurrences in the South Fork Cumberland drainage are located in BSF and are not affected by any known threats because they are remotely located from trail access and protected from timber harvest.

Thus, available data indicate that the threat of habitat modification or curtailment of the species' range has been addressed.

Limited Distribution and Small Population Sizes

The listing rule for Cumberland sandwort identified the species' restricted distribution, limited to a small portion of the Cumberland Plateau in northern Tennessee and southern Kentucky, and the small size of many populations, as factors increasing the risks of population loss and potential extinction of the species. The species is still restricted to a small portion of the Cumberland Plateau, but the number of known occurrences has increased from 11 at the time of listing (Wofford and Smith 1980, pp. 9-18, 53 FR 23745) to 71 currently (TNHID 2018). Three projects have been funded to support searches for new Cumberland sandwort occurrences (KSNPC 1991, entire; TDEC 2000, entire; TDEC 2008, entire). The single search effort that occurred in Kentucky, only in McCreary County, did not expand the known range of Cumberland sandwort, but confirmed the known occurrence located in Big Spring Hollow and documented that thousands of plants were present at two sites mapped at the occurrence (KSNPC 1991, entire). Searches conducted in Tennessee in 2000 (TDEC 2000, entire) and 2006-2007 (TDEC 2008, entire) produced records for 30 new occurrences on conservation lands in Fentress, Pickett, and Scott counties, Tennessee. In addition to these three Cumberland sandwort survey projects, surveys at PCNA for prospective trail routes have produced records for six additional occurrences on conservation lands in Fentress County (TNHID 2018). These survey efforts, funded in part by the Service via Section 6 grants to state agencies for endangered species recovery, contributed greatly to increasing the species' distribution to the 71 extant occurrences known today.

Fourteen protected and self-sustaining occurrences are located outside of Pickett County, satisfying the recovery criterion concerning geographic distribution. And 12 of the 71 occurrences are located in the Obey River watershed in Tennessee, increasing the species' distribution beyond the South Fork Cumberland watershed, to which the species was thought to be restricted at the time of listing.

The listing rule discussed small population size as a threat to many occurrences, but did not include information on population sizes at the time or specify the number of individuals or the size of habitat area occupied that would be necessary to buffer against extinction risk. As discussed above in Recovery Criteria, we used available data to evaluate the species' abundance at known occurrences. We consider populations consisting of fewer than 100 individuals or occupying less than 1 m² of habitat to be at heightened risk of (1) losing genetic variation due to drift (change in the frequency of alleles in a population due to random, stochastic events), and (2) inbreeding, which decreases the likelihood that an individual will receive pollen from a compatible mate and produce viable offspring (Allendorf and Luikart 2007, pp. 122-123). However, we note that the risk of inbreeding depression due to unavailability of incompatible mates might be low for Cumberland sandwort, as self-compatibility apparently evolved twice in geographically distant populations of the closely related congener Mononeuria (=Arenaria) glabra at the edges of the species' range (Wyatt 1984, p. 815). Based on available data, 12 populations consist of fewer than 100 individuals or occupy less than 1 m² of habitat. Six of these 12 have been known to persist as small populations for lengths of time ranging from 24 to 41 years, indicating that even small poulations are likely to persist for the foreseeable future (TNHID 2018). The remaining six were discovered in 2000 or later. In contrast, 27 occurrences contain 100-1,000 individuals or occupy 1 to 5 m² of habitat, and 30 occurrences contain more than 1,000 individuals or occupy greater than 5 m² of habitat. Estimates of abundance available for 24 of the largest occurrences indicate that they collectively hold at least 67,000 Cumberland sandwort individuals. These data demonstrate that small population size is not a threat to the species, affecting less than 20 percent of the 71 extant Cumberland sandwort occurrences.

Techniques for micropropagating, cryopreserving, and outplanting Cumberland sandwort have been developed and successfully applied to establish an introduced population at DBNF (Pence et al. 2011, entire), which is not counted among the 71 extant occurrences discussed above. This introduced population has grown from an initial outplanting of 63 individuals to 255 individuals, representing multiple life stages, as of 2017 (Taylor 2018, pers. comm.). Eight years after initial outplanting, the genetic variation in this population, which was established in 2005 from seven genetic lines, was approaching levels of genetic diversity comparable to the source population (Philpott et al. 2014, entire). The Missouri Botanical Garden (MBG) has seeds in storage from BSF and PSP that were collected in 1991, 1994, 2005, and 2014 (Dell 2018, pers. comm.). Collections were made at multiple points in time to maintain seed viability in storage. While a cultivated source of plants is not currently maintained ex situ, the need for doing so is mitigated by the development of methods to micropropagate the species from cuttings and by availability of seeds in ex situ collections, providing two potential methods for propagating the species should it become necessary to do so.

Available data support the determination that Cumberland sandwort is not likely to become endangered in the foreseeable future due to limited distribution or small population sizes.

Effects of 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). The term “climate change” thus 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 2014, pp. 119-120). A recent compilation of climate change and its effects is available from reports of the IPCC (IPCC 2014, entire).

The IPCC concluded that evidence of warming of the climate system is unequivocal (IPCC 2014, pp. 2, 40). Numerous long-term climate changes have been observed including changes in arctic temperatures and ice, widespread changes in precipitation amounts, changes in ocean salinity, and aspects of extreme weather including heavy precipitation and heat waves (IPCC 2014, pp. 40-44). Since 1970, the average annual temperature across the Southeast has increased by about 2 degrees Fahrenheit (°F), with the greatest increases occurring during winter months. The geographic extent of areas in the Southeast region affected by moderate to severe spring and summer drought has increased over the past three decades by 12 and 14 percent, respectively (Karl et al. 2009, p. 111). These trends are expected to increase. Rates of warming are predicted to more than double in comparison to what the Southeast has experienced since 1975, with the greatest increases projected for summer months. Depending on the emissions scenario used for modeling change (IPCC 2000, entire), average temperatures are expected to increase by 4.5 °F (scenario B1) to 9 °F (scenario A2) by the 2080s (Karl et al. 2009, p. 111). While there is considerable variability in rainfall predictions throughout the region, increases in evaporation of moisture from soils and loss of water by plants in response to warmer temperatures are expected to contribute to increased frequency, intensity, and duration of drought events (Karl et al. 2009, p. 112).

We used the National Climate Change Viewer (NCCV), a climate-visualization tool developed by the U.S. Geological Survey (USGS), to generate future climate projections across the range of Cumberland sandwort. The NCCV is a web-based tool for visualizing projected changes in climate and water balance at watershed, State, and county scales (USGS 2017). This tool uses air temperature and precipitation data from 30 downscaled climate models for two Representative Concentration Pathway (RCP) scenarios, RCP 4.5 and RCP 8.5, as input to a simple water-balance model to simulate changes in the surface water balance over historical and future time periods, providing insight into potential for climate-driven changes in water resources. To evaluate the maximum effects of climate change in the future, we used projections from RCP 8.5, which is the most aggressive emissions scenario wherein greenhouse gases (GHGs) rise unchecked through the end of the century, to characterize projected future changes in climate and water resources, averaged across the five counties encompassing the range of Cumberland sandwort. The projections estimate change in mean annual values, comparing the period 1981 through 2010 with 2050 through 2074, for maximum and minimum temperature, monthly precipitation and runoff, snowfall, soil water storage, and evaporative deficit.

Within the range of Cumberland sandwort, the NCCV projects that, under the more extreme RCP 8.5 scenario, maximum temperature will increase by 3.2 degrees Celsius (°C) (5.7 degrees °F), minimum temperature will increase by 3.1 °C (5.6 °F), precipitation will increase by 5.36 mm (0.2 in) per month, soil water storage will decrease by 12.2 mm (0.5 in) annually, and evaporative deficit will increase by 4.6 mm (0.2 in) per month. Projected changes in snowfall are negligible. These estimates indicate that, despite projected minimal increases in annual precipitation, anticipated increases in maximum and minimum temperatures will offset those gains, leading to a net loss in projected runoff and soil water storage. The most notable change with respect to water balance between the two time periods is that soil storage projections are projected to be significantly reduced during the months of June through November for the period 2050 through 2074. Based on these projections, Cumberland sandwort will on average be exposed to increased temperatures across its range which, despite limited increases in precipitation, are expected to decrease soil water available during the growing season.

Assessments of vulnerability of federally listed plants in Tennessee to projected climate change have been conducted by two different groups (Glick et al. 2015, entire; Kwit 2018, pers. comm.) using version 2.1 of NatureServe's Climate Change Vulnerability Index (CCVI) (Young et al. 2015, entire). The CCVI is an assessment tool that combines results of downscaled climate predictions, characterizing direct exposure to projected climate change, with readily available information about a species' natural history, distribution, and landscape circumstances, which together influence sensitivity to change, to predict whether it will likely suffer a range contraction and/or population reductions due to the effects of climate change. For these assessments using the CCVI, climate change projections were based on ensemble climate predictions, representing a median of 16 major global circulation models, using a “middle of the road” scenario (i.e., emission scenario A1B of the IPCC (IPCC 2000, entire)) for GHG emissions (Young et al. 2015, p. 14), in contrast to the more extreme scenario that we used in the NCCV to project climate and water balance changes reported above. From these two assessments, Cumberland sandwort was ranked as either “presumed stable” (Glick et al. 2015, p. 40) or “moderately vulnerable” (Kwit 2018, pers. comm.), the latter indicating the species' abundance and/or range extent within the geographical area assessed would likely decrease by 2050 (Young et al. 2015, p. 45).

The disparate results between these two assessments conducted using the same tool illustrate that there is some subjectivity involved in evaluating aspects of a species' biology and ecology as they relate to CCVI sensitivity factors used to model potential vulnerability to projected climate change. In the case of Cumberland sandwort, differing judgements of the species' physiological dependence on specific thermal and hydrological niches, restriction to uncommon geological features, and potential for phenological response to changing climate resulted in different outcomes with respect to predicted vulnerability to climate change. In the assessment that ranked Cumberland sandwort as moderately vulnerable, each of these factors were individually ranked as being more likely to increase the species' overall vulnerability than in the contrasting assessment that produced a rank of presumed stable.

Despite having produced different vulnerability ranks, both assessments ranked Cumberland sandwort among the least vulnerable to projected climate change of the Federally listed plant species evaluated in Tennessee (Glick et al. 2015, p. 40; Kwit 2018, pers. comm.). While the rank of moderately vulnerable indicates that Cumberland sandwort would likely decrease in abundance and/or range extent by 2050, neither assessment using the CCVI predicted that the species would become extinct within that timeframe or decrease significantly in abundance and/or range extent. Factors contributing to potential resilience of the species to projected climate change include the topographic complexity of the landscape it occupies, general lack of fragmentation among habitats where the species occurs, high abundance at some occurrences, and the fact that most occurrences are located on conservation lands where known threats can be monitored and managed.

Evidence of Cumberland sandwort's potential resilience to the threat of increased drought frequency and intensity is provided by examining available monitoring data in relation to drought records available from 2000 through present. We acquired data from the U.S. Drought Monitor (USDM) summarizing the number of weeks that the geographic area where Cumberland sandwort occurs experienced “extreme” or “exceptional” droughts for periods of more than 2 consecutive weeks (USDM 2019). The USDM is jointly produced by the National Drought Mitigation Center at the University of Nebraska-Lincoln, the United States Department of Agriculture, and the National Oceanic and Atmospheric Administration. Since 2000, the four Tennessee counties, where all but one Cumberland sandwort occurrence are located, have experienced periods of such drought during 2007, 2008, and 2016. Prolonged drought conditions began during the last half of June 2007 and extended into late winter or spring of 2008, depending on the county. “Extreme” or “exceptional” drought conditions in these counties started again sometime between August and October 2008, ending in early December. During June 2007 through the end of 2008, these counties experienced between 26 and 53 cumulative weeks of “extreme” or “exceptional” drought conditions for periods that lasted 2 or more consecutive weeks. These counties did not experience such drought conditions again until a 3-week period during November 2016.

To determine whether any population declines recorded through monitoring corresponded with documented periods of local drought, we examined available data (TNHID 2018) for all sites where monitoring has encompassed the two drought periods discussed above. There were 20 occurrences with data spanning this time range, only one (Tennessee EO 7) of which was judged to have declined. More than 450 plants were estimated to have been present at this site in November 2007, and 351 plants were counted at the site in September 2017. Cumberland sandwort was estimated to have occupied approximately 4 m² of habitat in both years. This site's medium rank for abundance did not change over this time period. The other 19 sites remained stable over the time period encompassing the drought conditions discussed above, with the exception of three that increased. Available monitoring data, when considered in conjunction with data documenting droughts of extreme or exceptional severity within the range of Cumberland sandwort, indicate that the species is resilient to this climate phenomenon. Small populations are likely the most vulnerable to reductions or loss due to climate change. Monitoring data spanning the time period of the droughts discussed above were available for 3 occurrences with fewer than 100 individuals or that were less than 1 m² in size, all of which remained stable. Thus, we conclude that climate change will not threaten the viability of the species into the foreseeable future.

Cumulative Effects

The stressors discussed in the analysis above could work in concert with each other and result in a cumulative adverse effect to Cumberland sandwort, e.g., one stressor may make the species more vulnerable to other threats. For example, stressors discussed under Factor A that individually do not rise to the level of a threat could together result in habitat degradation or loss. In instances where multiple habitat stressors act in concert with small population sizes, occurrences might lack resilience needed for population stability or growth. However, the potential stressors we identified either have not occurred to the extent originally anticipated at the time of listing, or appear to be either well-tolerated by the species or adequately managed as described in this proposal to delist the species. Our analysis has identified no range-wide threats or stressors with significant effects to all occurrences. We characterized the presence and relative severity of threats resulting from disturbances of substrates or altered forest conditions. Only 7 of the 71 extant occurrences were found to be potentially exposed to both substrate disturbance and altered forest condition. For reasons discussed below in Inadequacy of Regulatory Mechanisms, we do not anticipate stressors to increase on conservation lands where nearly all of the occurrences are located. Furthermore, the increases documented in the number and size of many occurrences since the species was listed do not indicate that cumulative effects of various activities and stressors are affecting the viability of the species at this time or into the future.

Inadequacy of Existing Regulatory Mechanisms

The Commonwealth of Kentucky and the State of Tennessee both list Cumberland sandwort as an endangered species. Conservation efforts are directed towards such species by KSNPC and TDEC, using funding and authorities provided through cooperative agreements with the Service under section 6 of the Act for endangered species recovery. Should Cumberland sandwort be delisted, these agencies would no longer receive such funding specifically for Cumberland sandwort conservation efforts, but could allocate a portion of overall funds they receive for post-delisting monitoring of the species.

The Kentucky Rare Plants Recognition Act, Kentucky Revised Statutes (KRS), chapter 146, section 600-619, directs the KSNPC to identify plants native to Kentucky that are in danger of extirpation within Kentucky and report every 4 years to the Governor and General Assembly on the conditions and needs of these endangered or threatened plants. The list of endangered or threatened plants in Kentucky is found in the Kentucky Administrative Regulations, title 400, chapter 3:040. The statute also recognizes the need to develop and maintain information regarding distribution, population, habitat needs, limiting factors, other biological data, and requirements for the survival of plants native to Kentucky. However, this statute does not include any regulatory prohibitions of activities or direct protections for any species included in the list. It is expressly stated in KRS 146.615 that this list of endangered or threatened plants shall not obstruct or hinder any development or use of public or private land. Furthermore, the intent of this statute is not to ameliorate the threats identified for the species, but to provide information on the species.

The Tennessee Rare Plant Protection and Conservation Act of 1985 (T.C.A. 11-26-201) authorizes the TDEC to, among other things, conduct investigations on species of rare plants throughout the State of Tennessee; maintain a listing of species of plants determined to be endangered, threatened, or of special concern within the State; and regulate the sale or export of endangered species via a licensing system. This statute forbids persons from knowingly uprooting, digging, taking, removing, damaging, destroying, possessing, or otherwise disturbing for any purpose, any endangered species from private or public lands without the written permission of the landowner, lessee, or other person entitled to possession and prescribes penalties for violations. The TDEC may use the list of threatened and special concern species when commenting on proposed public works projects in Tennessee, and the department shall encourage voluntary efforts to prevent the plants on this list from becoming endangered species. It may not, however, be used to interfere with, delay, or impede any public works project.

Cumberland sandwort listing under these State laws may continue following Federal delisting, although Federal delisting may prompt changes in status in Kentucky or Tennessee. However, we are unaware of any planned changes to State protections at this time.

Further, Cumberland sandwort habitats on both state and federal conservation lands would remain protected by rules, regulations, or plans governing the establishment or management of those lands, relevant sections of which are summarized below. As noted above in Table 1, 66 of the 71 extant Cumberland sandwort occurrences are located on Federal or State conservation lands at BSF, PSF, PCNA, and PSP.

Establishment of the BSF was authorized by section 108 of the Water Resources Act of 1974. The NPS manages the 125,000-acre (ac) BSF according to prescriptions established for eight management zones in Alternative D of the Final General Management Plan/Environmental Impact Statement for Big South Fork National River and Recreation Area, Kentucky and Tennessee (NPS 2005, entire). Under this management framework, habitats occupied by Cumberland sandwort and those that are potentially suitable for the species fall within the Sensitive Resource Protection Zone, which is managed to reflect natural processes and be carefully protected from unnatural degradation (NPS 2005, pp. 31-40).

The 20,887-ac PSF was established in 1935 on lands donated to the State of Tennessee by Stearns Coal and Lumber Company (retrieved March 13, 2019 from https://www.tn.gov/agriculture/forests/state-forests/pickett.html ). The Rules of the Tennessee Department of Agriculture Division of Forestry, Chapter 0080-7-1 Protection of State Forests, prohibit destruction or damaging of any natural resource or collection of plants or botanical specimens, unless authorized by permit from the district forester. Pickett CCC Memorial State Park is situated within the PSF. The Rules of the Tennessee Department of Environment and Conservation, Chapter 0400-0202 Public Use and Recreation, prohibit users of State parks from destroying, digging, cutting, removing, or possessing any tree, shrub or other plant, except as permitted by the Assistant Commissioner of Parks and Recreation (Rule 0400-02-02-.18). Permits may only be issued for scientific or educational purposes (Rule 0400-02-02-.23). The 3,000-ac PCNA is contiguous to PSF and very near PSP, the latter of which provides local management of the natural area. The Tennessee Natural Areas Preservation Act of 1971 forbids the unauthorized removal or destruction of any rare, threatened, or endangered species of plants in any natural areas, with civil penalties of up to $10,000 per day for each day during which the prohibited act occurs (T.C.A § 11-14-1115). Thus, we do not anticipate stressors to increase on conservation lands where nearly all of the occurrences are located. For the reasons discussed above, we conclude that inadequacy of regulatory mechanisms will not threaten the viability of the species into the foreseeable future.

Determination of Cumberland Sandwort's Status

Section 4 of the Act (16 U.S.C. 1533) and its implementing regulations (50 CFR part 424) set forth the procedures for determining whether a species meets the definition of “endangered species” or “threatened species.” The Act defines an “endangered species” as a species that is “in danger of extinction throughout all or a significant portion of its range,” and a “threatened species” as a species that is “likely to become an endangered species within the foreseeable future throughout all or a significant portion of its range.” The Act requires that we determine whether a species meets the definition of “endangered species” or “threatened species” because of any of the following 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.

Status Throughout All of Its Range

After evaluating threats to the species and assessing the cumulative effect of the threats under the section 4(a)(1) factors, we have found that since listing under the Act, Cumberland sandwort representation has increased with the discovery of occurrences in the Obey River watershed. Redundancy also has increased from 11 occurrences at the time of listing to 71 occurrences known to be extant, including 25 of the 28 occurrences that were included in the species recovery plan. An assessment of resiliency of these occurrences, taking into account estimated abundance, substrate condition, and forest condition, indicates that 57 ranked medium or higher, which we consider to be resilient. Of these resilient occurrences, 42 are counted towards meeting and exceeding recovery criteria because they are self-sustaining and located on protected land. Of the 15 resilient occurrences that are not counted towards meeting recovery criteria, 10 are located on protected lands but lack a sufficient number of observations over time to judge trends in their abundance and evaluate whether they are self-sustaining; thus, we expect they will also contribute to the species' overall resiliency and redundancy, ensuring its ability to withstand future catastrophic events (but we are not relying upon these 10 to make this proposed determination). Because Cumberland sandwort has increased in representation and redundancy, generally, and in particular with respect to numbers of resilient, self-sustaining and protected occurrences, we expect this species to persist into the future.

We have carefully assessed the best scientific and commercial information available regarding the threats faced by the Cumberland sandwort in developing this proposed rule. Threats reported at the time of listing related to habitat loss and curtailment of range (Factor A) have been managed in many locations, and available data indicate the species possesses greater resilience to effects of substrate disturbance from trampling and various activities and to effects of timber harvesting in nearby areas than was assumed at the time of listing.

We have analyzed or evaluated potential effects of climate change and low population size (Factor E) and determined that they are not significant threats to the species nor are likely to be in the foreseeable future as defined above. Although not all state and federal regulatory mechanisms (Factor D) will be in effect in the event that Cumberland sandwort is delisted, those remaining are likely to be adequate to protect the Cumberland sandwort from threats to its habitat, given the fact that 66 of the 71 extant occurrences are located on Federal or State conservation lands. The net effect of current and foreseeable future stressors to the species, after considering applicable conservation measures and the existing regulatory mechanisms, is not sufficient to cause the species to meet the definition of an endangered or threatened species. Thus, after assessing the best available information, we conclude that the Cumberland sandwort no longer meets the definition of endangered or threatened under the Act throughout all of its range.

Status Throughout a Significant Portion of Its Range

Under the Act and our implementing regulations, a species may warrant listing if it is in danger of extinction or likely to become so in the foreseeable future throughout all or a significant portion of its range.

Having determined that the Cumberland sandwort is not in danger of extinction or likely to become so in the foreseeable future throughout all of its range, we now consider whether it may be in danger of extinction or likely to become so in the foreseeable future in a significant portion of its range. The range of a species can theoretically be divided into portions in an infinite number of ways, so we first screen the potential portions of the species' range to determine if there are any portions that warrant further consideration. To do the “screening” analysis, we ask whether there are portions of the species' range for which there is substantial information indicating that: (1) The portion may be significant; and, (2) the species may be, in that portion, either in danger of extinction or likely to become so in the foreseeable future. For a particular portion, if we cannot answer both questions in the affirmative, then that portion does not warrant further consideration and the species does not warrant listing because of its status in that portion of its range. Conversely, we emphasize that answering both of these questions in the affirmative is not a determination that the species is in danger of extinction or likely to become so in the foreseeable future throughout a significant portion of its range—rather, it is a step in determining whether a more-detailed analysis of the issue is required.

If we answer these questions in the affirmative, we then conduct a more thorough analysis to determine whether the portion does indeed meet both of the “significant portion of its range” prongs: (1) The portion is significant and (2) the species is, in that portion, either in danger of extinction or likely to become so in the foreseeable future. Confirmation that a portion does indeed meet one of these prongs does not create a presumption, prejudgment, or other determination as to whether the species is an endangered species or threatened species. Rather, we must then undertake a more detailed analysis of the other prong to make that determination. Only if the portion does indeed meet both prongs would the species warrant listing because of its status in a significant portion of its range.

At both stages in this process—the stage of screening potential portions to identify any portions that warrant further consideration and the stage of undertaking the more detailed analysis of any portions that do warrant further consideration—it might be more efficient for us to address the “significance” question or the “status” question first. Our selection of which question to address first for a particular portion depends on the biology of the species, its range, and the threats it faces. Regardless of which question we address first, if we reach a negative answer with respect to the first question that we address, we do not need to evaluate the second question for that portion of the species' range.

The range of Cumberland sandwort is restricted to a small geographic area in portions of five counties, with high similarity in geological and ecological conditions among occupied sites. Within this geographic area, the species is known from two watersheds, South Fork Cumberland and Obey River, where there are 59 and 12 extant occurrences, respectively. Therefore, applying the process described above, we first evaluated the status of Cumberland sandwort to determine if any threats or population declines were concentrated in any specific portion of the range. Threats related to habitat modification or curtailment of range primarily affect occurrences in the South Fork Cumberland drainage. Our analysis of the species resilience (see above, Recovery), which integrated information on abundance and threats, determined that 45 of the occurrences within the South Fork Cumberland and all of the occurrences within the Obey River drainages had resiliency indices of medium or higher. We have determined that 40 of these resilient occurrences in the South Fork Cumberland and 2 in the Obey River drainages are protected and contribute towards achieving the recovery criteria. The presence of 40 protected and self-sustaining occurrences in the South Fork Cumberland indicates that threats are not concentrated in this drainage so as to affect the representation, redundancy, or resiliency of the Cumberland sandwort. Nine protected occurrences in the Obey River watershed have resiliency indices of medium or higher, but lack sufficient monitoring data to evaluate trends in abundance and determine whether they are self-sustaining. Due to their locations on protected lands, primarily within PCNA where proposed trail routes are surveyed to minimize adverse effects to Cumberland sandwort (TDEC no date, p. 10-11), we expect that these nine occurrences will remain stable for the foreseeable future, adding to the resilience, representation, and redundancy afforded by the 42 occurrences currently considered to contribute to achieving recovery criteria. Based on the distribution of 42 protected and self-sustaining occurrences among the two watersheds, all located on conservation lands managed according to rules, regulations, or management plans (NPS 2005, pp. 31-39, TDEC no date, entire) that protect Cumberland sandwort, we have determined that threats related to habitat modification or curtailment of range are not concentrated in any portion of the species' range so as to affect its representation, redundancy, or resiliency.

We have reviewed other potential threats and conclude that none of them are concentrated in any portion of the species' range so as to affect the representation, redundancy, or resiliency of the species.

Therefore, we conclude, based on this screening analysis, that no portions of the Cumberland sandwort's range warrant further consideration to determine whether the species may be in danger of extinction or likely to become so in the foreseeable future in a significant portion of its range. Thus, we conclude that the species is not an endangered species or threatened species based on its status in a significant portion of its range. Our approach to analyzing significant portions of the species' range in this determination is consistent with the courts' holdings in Desert Survivors v. Department of the Interior, No. 16-cv-01165-JCS, 2018 WL 4053447 (N.D. Cal. Aug. 24, 2018); Center for Biological Diversity v. Jewell, 248 F. Supp. 3d, 946, 959 (D. Ariz. 2017); and Center for Biological Diversity v. Everson, 2020 WL 437289 (D.D.C. Jan. 28, 2020).

Determination of Status

Our review of the best available scientific and commercial information indicates that the Cumberland sandwort does not meet the definition of an endangered species or a threatened species in accordance with sections 3(6) and 3(20) of the Act. Therefore, we propose to remove the Cumberland sandwort from the List of Endangered and Threatened Plants.

Effects of This Proposed Rule

This proposal, if made final, would revise 50 CFR 17.12 (h) to remove the Cumberland sandwort from the Federal List of Endangered and Threatened Plants. The prohibitions and conservation measures provided by the Act, particularly through sections 7 and 9, would no longer apply to Cumberland sandwort. Federal agencies would no longer be required to consult with us under section 7 of the Act to ensure that any action authorized, funded, or carried out by them is not likely to jeopardize the Cumberland sandwort's continued existence.

This rule will not affect Cumberland sandwort's status as a threatened or endangered species under State laws or suspend any other legal protections provided by those laws. States may have more restrictive laws protecting wildlife, and these will not be affected by this Federal action. However, this proposed rule may prompt either Kentucky or Tennessee to remove protection for the Cumberland sandwort under their endangered species laws, although we are not aware of any such intention at this time.

Post-Delisting Monitoring

Section 4(g)(1) of the Act requires us to monitor for not less than 5 years the status of all species that are delisted due to recovery. Post-delisting monitoring (PDM) refers to activities undertaken to verify that a species delisted due to recovery remains secure from the risk of extinction after the protections of the Act no longer apply. The primary goal of PDM is to monitor the species to ensure that its status does not deteriorate, and if a decline is detected, to take measures to halt the decline so that proposing it as endangered or threatened is not again needed. If at any time during the monitoring period, data indicate that protective status under the Act should be reinstated, we can initiate listing procedures, including, if appropriate, emergency listing. At the conclusion of the monitoring period, we will review all available information to determine if re-listing, the continuation of monitoring, or the termination of monitoring is appropriate.

Section 4(g) of the Act explicitly requires that we cooperate with the States in development and implementation of PDM programs. However, we remain ultimately responsible for compliance with section 4(g) and, therefore, must remain actively engaged in all phases of PDM. We also seek active participation of other entities that are expected to assume responsibilities for the species' conservation after delisting.

We have prepared a draft PDM Plan for Cumberland sandwort (Service 2018). The draft plan describes:

(1) The Cumberland sandwort's condition at the time of delisting;

(2) Thresholds or triggers for potential monitoring outcomes and conclusions;

(3) Frequency and duration of monitoring;

(4) Monitoring methods including sampling considerations; and

(5) Data compilation and reporting procedures and responsibilities.

The draft plan also proposes a PDM implementation schedule including timing and responsible parties.

Concurrent with this proposed delisting rule, we announce the draft plan's availability for public review at http://www.regulations.gov under Docket Number FWS-R4-ES-2019-0080. Copies can also be obtained from the Service's Tennessee Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT). We seek information, data, and comments from the public regarding the draft PDM plan.

Required Determinations

Clarity of the Proposed Rule

We are required by Executive Orders 12866 and 12988 and by the Presidential Memorandum of June 1, 1998, to write all rules in plain language. This means that each rule we publish must:

(a) Be logically organized;

(b) Use the active voice to address readers directly;

(c) Use clear language rather than jargon;

(d) Be divided into short sections and sentences; and

(e) Use lists and tables wherever possible.

If you feel that we have not met these requirements, send us comments by one of the methods listed in ADDRESSES. To better help us revise the rule, your comments should be as specific as possible. For example, you should tell us the numbers of the sections or paragraphs that are unclearly written, which sections or sentences are too long, the sections where you feel lists or tables would be useful, etc.

National Environmental Policy Act

We have determined that we do not need to prepare an environmental assessment or environmental impact statement, as defined in the National Environmental Policy Act (42 U.S.C 4321 et seq.), in connection with regulations adopted pursuant to section 4(a) of the Endangered Species Act. We published a notice outlining our reasons for this determination in the Federal Register on October 25, 1983 (48 FR 49244).

Government-to-Government Relationship With Tribes

In accordance with the President's memorandum of April 29, 1994, “Government-to-Government Relations with Native American Tribal Governments” (59 FR 22951), Executive Order 13175, and the Department of the Interior's manual at 512 DM 2, we readily acknowledge our responsibility to communicate meaningfully with recognized Federal Tribes on a government-to-government basis. We have determined that there are no tribal lands that may be affected by this proposal.

References Cited

A complete list of references cited is available at http://www.regulations.gov under Docket Number FWS-R4-ES-2019-0080, or upon request from the Field Supervisor, Tennessee Field Office (see FOR FURTHER INFORMATION CONTACT).

Authors

The primary authors of this document are the staff members of the Tennessee Ecological Services Field Office (see FOR FURTHER INFORMATION CONTACT).

List of Subjects in 50 CFR Part 17

• Endangered and threatened species
• Exports
• Imports
• Reporting and recordkeeping requirements
• Transportation

Proposed Regulation Promulgation

Accordingly, we propose to amend part 17, subchapter B of chapter I, title 50 of the Code of Federal Regulations, as set forth below:

PART 17—ENDANGERED AND THREATENED WILDLIFE AND PLANTS

1. The authority citation for part 17 continues to read as follows:

Authority: 16 U.S.C. 1361-1407; 1531-1544; 4201-4245, unless otherwise noted.

2. Amend § 17.12(h) by removing the entry for “ Arenaria cumberlandensis” under “FLOWERING PLANTS” from the List of Endangered and Threatened Plants.