Endangered and Threatened Wildlife and Plants; Proposed Threatened Species Status for Sideroxylon reclinatum ssp. austrofloridense (Everglades Bully), Digitaria pauciflora (Florida Pineland Crabgrass), and Chamaesyce deltoidea ssp. pinetorum (Pineland Sandmat) and Endangered Species Status for Dalea carthagenensis var. floridana (Florida Prairie-Clover)

DEPARTMENT OF THE INTERIOR

Fish and Wildlife Service

50 CFR Part 17

[Docket No. FWS-R4-ES-2016-0090;4500030113]

RIN 1018-BB48

Endangered and Threatened Wildlife and Plants; Proposed Threatened Species Status for Sideroxylon reclinatum ssp. austrofloridense (Everglades Bully), Digitaria pauciflora (Florida Pineland Crabgrass), and Chamaesyce deltoidea ssp. pinetorum (Pineland Sandmat) and Endangered Species Status for Dalea carthagenensis var. floridana (Florida Prairie-Clover)

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Proposed rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), propose threatened species status under the Endangered Species Act of 1973 (Act), as amended, for

Sideroxylon reclinatum

ssp.

austrofloridense

(Everglades bully),

Digitaria pauciflora

(Florida pineland crabgrass) and

Chamaesyce deltoidea

ssp.

pinetorum

(pineland sandmat), and endangered species status for

Dalea carthagenensis

var.

floridana

(Florida prairie-clover). All four plants are from south Florida. If we finalize this rule as proposed, it would extend the Act's protections to these plants. The effect of this regulation will be to add these species to the List of Endangered and Threatened Plants.

DATES:

We will accept comments received or postmarked on or before December 12, 2016. 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 November 25, 2016.

ADDRESSES:

You may submit comments by one of the following methods:

(1)

Electronically:

Go to the Federal eRulemaking Portal:

http://www.regulations.gov.

In the Search box, enter FWS-R4-ES-2016-0090, which is the docket number for this rulemaking. Then, in the Search panel on the left side of the screen, under the Document Type heading, click on the Proposed Rules link to locate this document. You may submit a comment by clicking on “Comment Now!”

(2)

By hard copy:

Submit by U.S. mail or hand-delivery to: Public Comments Processing, Attn: FWS-R4-ES-2016-0090; U.S. Fish and Wildlife Service Headquarters, MS: BPHC, 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).

FOR FURTHER INFORMATION CONTACT:

Roxanna Hinzman, Field Supervisor, U.S. Fish and Wildlife Service, South Florida Ecological Services Office, 1339 20th Street, Vero Beach, FL 32960, by telephone 772-562-3909, or by facsimile 772-562-4288. Persons who use a telecommunications device for the deaf (TDD) may call the Federal Information Relay Service (FIRS) at 800-877-8339.

SUPPLEMENTARY INFORMATION:

Executive Summary

Why we need to publish a rule.

Under the Act, if we determine that a species is an endangered or threatened species throughout all or a significant portion of its range, we are required to promptly publish a proposal in the

Federal Register

and make a determination on our proposal within 1 year. Listing a species as an endangered or threatened species and designations and revisions of critical habitat can only be completed by issuing a rule.

What this proposed rule does.

This document proposes the listing of the

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

and

Chamaesyce deltoidea

ssp.

pinetorum

as threatened species, and

Dalea carthagenensis

var.

floridana

as an endangered species. The four plants are currently candidate species for which we have on file sufficient information on biological vulnerability and threats to support preparation of a listing proposal, but for which development of a listing regulation has until now been precluded by other higher priority listing activities. This proposed rule reassesses all available information regarding status of and threats to the four plants.

The basis for our action.

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

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

consist primarily of habitat loss and modification through urban and agricultural development, and lack of adequate fire management (Factor A) and proliferation of nonnative invasive plants, stochastic events (hurricanes and storm surge), maintenance practices used on roadsides and disturbed sites, and sea level rise (SLR) (Factor E).

We will seek peer review.

We will seek comments from independent specialists to ensure that our proposed designation is based on scientifically sound data, assumptions, and analyses. We will invite these peer reviewers to comment on our listing proposal.

Information Requested

Public Comments

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

(1) The four plants' biology, range, and population trends, including:

(a) Biological or ecological requirements of these plants, including habitat requirements for establishment, growth, and reproduction;

(b) Genetics and taxonomy;

(c) Historical and current range including distribution patterns;

(d) Historical and current population levels, and current and projected trends; and

(e) Past and ongoing conservation measures for the plants, their habitat, or both.

(2) Factors that may affect the continued existence of these plants, which may include habitat modification or destruction, overutilization, disease, predation, the inadequacy of existing regulatory mechanisms, or other natural or manmade factors.

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

(4) Current or planned activities in the areas occupied by these plants and

potential effects (positive or negative) of these activities on these plants.

(5) Additional information concerning the biological or ecological requirements of these plants, including pollination and pollinators.

(6) Additional information concerning the current and projected effects of climate change, including sea level rise, on these plants and their habitat.

(7) Scientific information or analysis informing whether these plants more closely meet the definition of an endangered species or of a threatened species under the Act.

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

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

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

ADDRESSES

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

ADDRESSES

.

If you submit information via

http://www.regulations.gov,

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

http://www.regulations.gov.

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

http://www.regulations.gov,

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

FOR FURTHER INFORMATION CONTACT

).

Public Hearing

Section 4(b)(5) of the Act provides for one or more public hearings on this proposal, if requested. Requests for public hearings must be received within 45 days after the date of publication of this proposed rule in the

Federal Register

(see

DATES

). Such requests must be sent to the address shown in

FOR FURTHER INFORMATION CONTACT

. We will schedule public hearings on this proposal, if any are requested, and announce the dates, times, and places of those hearings, as well as how to obtain reasonable accommodations, in the

Federal Register

and local newspapers at least 15 days before the hearing.

Peer Review

In accordance with our joint policy on peer review published in the

Federal Register

on July 1, 1994 (59 FR 34270), we will seek the expert opinions of at least three appropriate and independent specialists regarding this proposed rule. The purpose of peer review is to ensure that our listing determination and critical habitat designation are based on scientifically sound data, assumptions, and analyses. The peer reviewers will have expertise in the biology, habitat, and conservation status of these plants, to help inform our determination.

Previous Federal Actions

Digitaria pauciflora

was first recognized as a candidate species on September 27, 1985 (50 FR 39526). The 1990 Candidate Notice of Review (CNOR) published in the

Federal Register

on February 21, 1990 (55 FR 6184), included

Digitaria pauciflora

as a candidate for listing under the Act. We determined at that time that listing was warranted, but precluded due to workloads and competing priorities.

Digitaria pauciflora

remained on the candidate list as published in the CNOR in 1993 (58 FR 51144, September 30, 1993). The CNOR was not published again until October 25, 1999, and it retained

Digitaria pauciflora

as a candidate and assigned a listing priority number (LPN) of 6; the 1999 CNOR first recognized

Chamaesyce deltoidea

ssp.

pinetorum

as a candidate and assigned an LPN of 12 and

Dalea carthagenensis

var.

floridana

as a candidate and assigned an LPN of 3 (64 FR 57534). Candidate species are assigned LPNs based on immediacy and magnitude of threats, as well as taxonomic status. The lower the LPN, the higher priority that species is for us to determine appropriate action using our available resources.

Digitaria pauciflora, Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

remained on the candidate list from 2001 to 2004 (66 FR 54808, October 30, 2001; 67 FR 40657, June 13, 2002; 69 FR 24876, May 4, 2004).

Sideroxylon reclinatum

ssp.

austrofloridense

was first recognized May 4, 2004, and was assigned an LPN of 12 (69 FR 24876, May 4, 2004). We published a finding for

Digitaria pauciflora, Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

in the 2005 CNOR on May 11, 2005 (70 FR 24870), in response to a petition received on May 11, 2004.

All four species remained candidates from 2005 to 2015 (70 FR 24870, May 11, 2005; 71 FR 53756, September 12, 2006; 73 FR 75176, December 10, 2008; 74 FR 57804, November 9, 2009; 75 FR 69222, November 10, 2010; 76 FR 66370, October 26, 2011; 77 FR 69994, November 21, 2012; 78 FR 70104, November 22, 2013; 79 FR 72450, December 5, 2014; 80 FR 80584, December 24, 2015).

On September 9, 2011, the Service entered into two settlement agreements regarding species on the candidate list at that time (Endangered Species Act Section 4 Deadline Litigation, No. 10-377 (EGS), MDL Docket No. 2165 (D.D.C. May 10, 2011)). This proposed listing rule fulfills the requirements of those settlement agreements for the 4 plant species.

Background

It is our intent to discuss below only those topics directly relevant to the listing of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

and

Chamaesyce deltoidea

ssp.

pinetorum

as threatened species and

Dalea carthagenensis

var.

floridana

as an endangered species in this proposed rule.

Sideroxylon reclinatum ssp. austrofloridense (Everglades bully)

Species Description

Corogin and Judd (2014, pp. 410-412) provide a detailed description of

Sideroxylon reclinatum

ssp.

austrofloridense.

The plant is a single- to many-stemmed shrub, 3-6 feet (ft) (1-2 meters (m)) tall. The branches are smooth, slightly bent, and somewhat spiny. The leaves are thin, oval-shaped, 0.8-2 inches (in) (2-5 centimeters (cm)) long, evergreen, lance-shaped, and fuzzy on their undersides. The flowers are in axillary cymes (Long and Lakela 1971, p. 679).

Sideroxylon reclinatum

ssp.

austrofloridense

is distinguished from the similar subspecies

S. reclinatum

ssp.

reclinatum

in Florida by its leaves, which are persistently pubescent (fuzzy) on their undersides, rather than smooth or pubescent only along the leaf midvein (Wunderlin and Hansen 2003, p. 603). Corogin and Judd (2014, p. 404) indicated the two subspecies are most reliably distinguished by differences in the micromorphology of the leaf epidermis, and by the extent of

distribution of

S. r.

ssp.

austrofloridense,

which is limited to extreme southern peninsular Florida.

Taxonomy

The genus

Sideroxylon

is represented by eight species in Florida. All of these species were previously assigned to the genus

Bumelia. Sideroxylon reclinatum,

the Florida bully, is represented by three subspecies that range nearly throughout Florida and into neighboring States. The Everglades subspecies was first recognized by Whetstone (1985, pp. 544-547) as

Bumelia reclinata

var.

austrofloridense,

then transferred to the genus

Sideroxylon

(Kartesz and Gandhi 1990, pp. 421-427). Kartesz and Gandhi (1990, pp. 421-427) made

Sideroxylon reclinatum

ssp.

austrofloridense

a subspecies rather than a variety; however, in plant nomenclature, the ranks of variety and subspecies are interchangeable.

Sideroxylon reclinatum

ssp.

austrofloridense

is used in the current treatment of the Florida flora (Wunderlin and Hansen 2016, p. 1).

The Integrated Taxonomic Information System (2016, p. 1) indicates that the taxonomic standing for

Sideroxylon reclinatum

ssp.

austrofloridense

(Whetstone) Kartesz and Gandhi is accepted. The online Atlas of Florida Vascular Plants (Wunderlin and Hansen 2016, p. 1) uses the name

S. reclinatum

ssp.

austrofloridense

(Whetstone), as does NatureServe (2016, p. 1).

Corogin and Judd (2014, p. 408) indicate that

Sideroxylon reclinatum

subsp.

austrofloridense

is differentiated from

S. reclinatum

subsp.

reclinatum

by a set of distinct characters at the micromorphological level.

The two taxa are also separated eco-geographically.

Sideroxylon reclinatum

subsp.

austrofloridense

is a narrow endemic, restricted to pine rockland and marl prairie habitats in a well-defined area of extreme southeastern peninsular Florida. Conversely,

Sideroxylon reclinatum

subsp.

reclinatum

is more wide-ranging, occurring coastally from southern Georgia west to Louisiana, and throughout Florida as far south as Broward County in the east, and Collier and Monroe Counties in the west. The only place where plants of both species overlap is within Big Cypress National Preserve (BCNP), at the western fringe of Everglades bully's range (Corrogin and Judd 2014, p. 409).

Climate

The climate of south Florida where

Sideroxylon reclinatum

ssp.

austrofloridense

occurs is classified as tropical savanna and is characterized by distinct wet and dry seasons and a monthly mean temperature above 18 degrees Celsius (°C) (64.4 degrees Fahrenheit (°F)) in every month of the year (Gabler

et al.

1994, p. 211). Freezes can occur in the winter months, but are infrequent. Rainfall in the area where

Sideroxylon reclinatum

ssp.

austrofloridense

occurs varies from an annual average of 153-165 cm (60-65 in) in the northern portion of the Miami Rock Ridge to an average of 140-153 cm (55-60 in) in the southern portion. Approximately 75 percent of yearly rainfall occurs during the wet season from June through September (Snyder

et al.

1990, p. 238).

Habitat

Sideroxylon reclinatum

ssp.

austrofloridense

grows in pine rockland habitat, marl prairie habitat, and within the ecotone between both habitats (Gann

et al.

2006, p. 12; Bradley

et al.

2013, p. 4, Gann 2015, p. 31). These habitats are maintained by regular fire, and are prone, particularly marl prairie, to annual flooding for several months during the wet season (Gann

et al.

2006, p. 13; Bradley

et al.

2013, p. 4).

Sideroxylon reclinatum

ssp.

austrofloridense

also grows on the sunny edges of rockland hammock habitat (Gann 2015, p. 412), which is fire-resistant. Historically, fire served to maintain the boundary between pine rockland and rockland hammock by eliminating the encroachment of hardwoods into pine rocklands. Absent natural or prescribed fire, many pine rocklands have succeeded to rockland hammock (FNAI 2010, p. 25). Canopy cover on the interior of rockland hammock is too dense to support herbs and smaller shrub species, such as

S. r.

ssp.

austrofloridense,

that require more sunlight.

Pine Rockland

Pine rockland is characterized by an open canopy of South Florida slash pine (

Pinus elliottii

var.

densa

) with a patchy understory of tropical and temperate shrubs and palms and a rich herbaceous layer of mostly perennial species including numerous species endemic to South Florida. Outcrops of weathered oolitic (small rounded particles or grains) limestone, known locally as pinnacle rock, are common, and solution holes may be present. This subtropical, pyrogenic flatland can be mesic or xeric depending on landscape position and associated natural communities (Florida Natural Areas Inventory (FNAI) 2010, p. 61).

Pine rockland has an open canopy of South Florida slash pine, generally with multiple age classes. The diverse, open shrub and subcanopy layer is composed of more than 100 species of palms and hardwoods, most derived from the tropical flora of the West Indies (FNAI 2010, p. 61). Many of these species vary in height depending on fire frequency, getting taller with time since fire. These include saw palmetto (

Serenoa repens

), cabbage palm (

Sabal palmetto

), silver palm (

Coccothrinax argentata

), brittle thatch palm (

Thrinax morrisii

), wax myrtle (

Myrica cerifera

), myrsine (

Rapanea punctata

), poisonwood (

Metopium toxiferum

), locustberry (

Byrsonima lucida

), varnishleaf (

Dodonaea viscosa

), tetrazygia (

Tetrazygia bicolor

), rough velvetseed (

Guettarda scabra

), marlberry (

Ardisia escallonioides

), mangrove berry (

Psidium longipes

), willow bustic (

Sideroxylon salicifolium

), and winged sumac (

Rhus copallinum

). Short-statured shrubs include running oak (

Quercus elliottii

), white indigoberry (

Randia aculeata

), Christmas berry (

Crossopetalum ilicifolium

), redgal (

Morinda royoc

), and snowberry (

Chiococca alba

).

Grasses, forbs, and ferns make up a diverse herbaceous layer ranging from mostly continuous in areas with more soil development and little exposed rock to sparse where more extensive outcroppings of rock occur. Typical herbaceous species include bluestems (

Andropogon

spp.,

Schizachyrium gracile, S. rhizomatum,

and

S. sanguineum

), arrowleaf threeawn (

Aristida purpurascens

), lopsided indiangrass (

Sorghastrum secundum

), hairawn muhly (

Muhlenbergia capillaris

), Florida white-top sedge (

Rhynchospora floridensis

), pineland noseburn (

Tragia saxicola

), devil's potato (

Echites umbellata

), pineland croton, several species of sandmats (

Chamaesyce

spp.), partridge pea (

Chamaecrista fasciculata

), coontie (

Zamia pumila

), maidenhair pineland fern (

Anemia adiantifolia

), Bahama brake (

Pteris bahamensis

), and lacy bracken (

Pteridium aquilinum

var.

caudatum

) (FNAI 2010, p. 62).

Pine rockland occurs on relatively flat, moderately to well drained terrain from 2 to 7 m (6.5 to 23 ft) above sea level (FNAI 2010, p. 62). The oolitic limestone is at or very near the surface, and there is very little soil development. Soils are generally composed of small accumulations of nutrient-poor sand, marl, clayey loam, and organic debris in depressions and crevices in the rock surface. Organic acids occasionally dissolve the surface limestone causing collapsed depressions in the surface rock called solution holes (FNAI 2010, p. 62). Drainage varies according to the porosity of the limestone substrate, but is generally rapid. Consequently, most

sites are wet for only short periods following heavy rains. During the rainy season, however, some sites may be shallowly inundated by slow-flowing surface water for up to 60 days each year (FNAI 2010, p. 62).

Pine rockland is maintained by regular fire, and susceptible to other natural disturbances such as hurricanes, frost events, and sea-level rise (Ross

et al.

1994, pp. 144-156). Fires historically burned on an interval of approximately every 3 to 7 years (FNAI 2010, p. 63) and were typically started by lightning strikes during the frequent summer thunderstorms (FNAI 2010, p. 63).

Presently, prescribed fire must be periodically introduced into pine rocklands to sustain community structure, prevent invasion by woody species, maintain high herbaceous diversity (Loope and Dunevitz 1981, pp. 5-6; FNAI 2010, p. 63), and prevent succession to rockland hammock. The amount of woody understory growth is directly related to the length of time since the last fire. Herbaceous diversity declines with time since last fire. The ecotone between pine rockland and rockland hammock is abrupt when regular fire is present in the system. However when fire is removed, the ecotone becomes more gradual and subtle as hammock hardwoods encroach into the pineland (FNAI 2010, p. 63).

Marl Prairie

Marl prairie is a sparsely vegetated, grass-dominated community found on marl substrates in South Florida. Marls are fine white calcareous muds formed from calcite precipitated by a mixture of green algae, blue green algae, and diatoms, known as periphyton. It is seasonally inundated (2 to 4 months) to a shallow depth averaging about 20 cm (8 in). Marl prairie is a diverse community, which may contain more than 100 species. Most of the marl prairie plant species contribute little cover and more than 90 percent of the cover is contributed by only two or three dominant species in any given area (FNAI 2010, p. 107). Dominants may include one or more of the following: Gulf hairawn muhly (

Muhlenbergia sericea

), spreading beaksedge (

Rhynchospora divergens

), Florida little bluestem (

Schizachyrium rhizomatum

), black bogrush (

Schoenus nigricans

), Elliott's lovegrass (

Eragrostis elliottii

), sand cordgrass (

Spartina bakeri

), and a short form of sawgrass (

Cladium jamaicense

) (Porter, Jr. 1967, pp. 937-942; FNAI 2010, p. 107). (Taxonomy of

Schizachyrium

and

Muhlenbergia

follows treatments in Flora of North America (2007)). Other characteristic species include southern beaksedge (

Rhynchospora microcarpa

), bluejoint panicum (

Panicum tenerum

), Gulfdune paspalum (

Paspalum monostachyum

), rosy camphorweed (

Pluchea rosea

), starrush whitetop (

Rhynchospora colorata

), alligator lily (

Hymenocallis palmeri

), arrowfeather threeawn (

Aristida purpurascens

), and narrowleaf yellowtops (

Flaveria linearis

) (Porter, Jr. 1967, pp. 937-942; FNAI 2010, p. 107).

Marl prairie depends on a short hydroperiod of 2 to 4 months. Longer hydroperiods favor the development of peat and the dominance of sawgrass; shorter hydroperiods permit the invasion of woody species.

Marl prairie normally dries out during the winter and is subject to fires at the end of the dry season; the most acres naturally burn in May (FNAI 2010, p. 108). Fires at this time (in contrast to dormant season fires) stimulate flowering of the dominant grasses (Main and Barry 2002, pp. 430-434). The herbaceous species recover rapidly from fire, and biomass reaches pre-fire levels at the end of 2 years. For the first 2 years after fire, this community will burn only patchily, if at all (FNAI 2010, p. 108). Reasons for the presence of dwarf cypress in some marl prairies and not others are unknown (FNAI 2010, p. 108). Wade

et al.

(1980, pp. 67-79) estimated dwarf cypress stands in marl prairie burn about once a decade due to low fire-carrying capacity of their sparse understory.

Historical Range

All known historical and current records for

Sideroxylon reclinatum

ssp.

austrofloridense

are summarized in table 1. The historical range of

S. reclinatum

ssp.

austrofloridense

is limited to Collier, Miami-Dade, and Monroe Counties, Florida. In Miami-Dade County, the plant was known from central and southern Miami-Dade County along the Miami Rock Ridge, which extends from Long Pine Key in the Everglades northward through urban Miami to the Miami River. In Monroe County, the plant was known from BCNP on the mainland, and was collected as far south as Key Largo, in the Florida Keys. In Collier County, the species has been recorded only within BCNP. This area constitutes a historical range of approximately 42 miles (mi) (66 kilometers (km)) (Gann

et al.

2002, p. 526; Corogin and Judd 2014, p. 412).

Current Range, Population Estimates, and Status

The current range of

Sideroxylon reclinatum

ssp.

austrofloridense

is BCNP, the Long Pine Key region of Everglades National Park (ENP), and pine rocklands adjacent to ENP (Hodges and Bradley 2006, p. 42; Gann

et al.

2006, p. 11; K. Bradley, pers. comm. 2007; J. Possley, pers. comm. 2011a; 2011b; J. Sadle, pers. comm. 2011; Bradley

et al.

2013, p. 4; Gann 2015, p. 30). The species is apparently extirpated from Key Largo. Hodges and Bradley (2006, p. 42) did not find

Sideroxylon reclinatum

ssp.

austrofloridense

in their surveys of pine rocklands on Key Largo, Big Pine Key, Cudjoe Key, and Lower Sugarloaf Key. This area constitutes a current range of approximately 42 mi (66 km) (Gann

et al.

2002, p. 526; Corogin and Judd 2014, p. 412).

The largest population occurs at Long Pine Key in ENP (Hodges and Bradley 2006, p. 42; Gann

et al.

2006, p. 11; Gann 2015, p. 9). The most recent information indicates that the baseline abundance estimate at Long Pine Key based on a log

10

abundance estimate is 10,000-100,000 plants (Gann

et al.

2006, pp. 9-11; Gann 2015, p. 29). Recent surveys of ENP have identified 14 occurrences of

Sideroxylon reclinatum

ssp.

austrofloridense

in Long Pine Key, expanding the known range in ENP (Gann 2015, p. 30).

In Miami-Dade County, outside ENP, pine rocklands tracts are orders of magnitude smaller and exist in a matrix of agricultural, commercial, and residential development. Possley and McSweeney (2005, p. 1) observed approximately 73 plants at Larry and Penny Thompson Park, within the Richmond Pine Rocklands. Possley (Fairchild Tropical Botanic Garden (FTBG), pers. comm. 2011a; 2011b) found extant populations at Quail Roost Pineland (two plants), Navy Well Pineland Preserve (four plants), and Sunny Palms Pinelands (two plants). The species had been observed in pine rocklands at Grant Hammock, and Pine Ridge Sanctuary (Bradley et al. 2013, p. 1). The species no longer occurs at the Nixon-Smiley Preserve.

Bradley et al. (2013, pp. 1-8) conducted surveys in the Gum Slough region of Lostmans Pines in BCNP and reported finding

Sideroxylon reclinatum

ssp.

austrofloridense

to have limited distribution within the study area. Seventeen plants were counted within pine rockland plots that were associated with marl prairie habitats (Bradley

et al.

2013, p. 4).

Table 1—Summary of the Status and Trends of the Known Occurrences of

Sideroxylon Reclinatum

ssp.

Austrofloridense

Population

Ownership

Most recent population estimate

(Year)

Status

Trend

Everglades National Park

National Park Service

10,000- 100,000 (2013)

Extant

Increasing.

Big Cypress National Preserve

National Park Service

17 (2013)

Extant

Insufficient data.

Larry Penny Thompson Park

Miami-Dade County

73 (2005)

Extant

Insufficient data.

Nixon-Smiley Preserve

Miami-Dade County

0 (Unknown)

Extirpated

Navy Wells Pineland Preserve

Miami-Dade County

4 (2011)

Extant

Insufficient data.

Sunny Palms Pineland

Miami-Dade County

2 (2011)

Extant

Insufficient data.

Pine Ridge Sanctuary

Private

Unknown

Extant

Insufficient data.

Lucille Hammock

Miami-Dade County

11-100 (2007)

Extant

Insufficient data.

South Dade Wetlands

Miami-Dade County

Unknown (2007)

Extant

Insufficient data.

Natural Forest Community #P-300

Private

2-10 (2007)

Extant

Insufficient data.

Natural Forest Community #P-310

Private

11-100 (2007)

Extant

Insufficient data.

Quail Roost Pineland

Miami-Dade County

2 (2011)

Extant

Insufficient data.

Grant Hammock

Unknown

Unknown (Unknown)

Extirpated

Key Largo

Unknown

No estimate (1948)

Extirpated

Biology

Life History and Reproduction

Little is known about the life history of

Sideroxylon reclinatum

ssp.

austrofloridense,

including pollination biology, seed production, and dispersal (Gann 2015, p. 31). Reproduction is sexual, with new plants generated from seeds. The species produces flowers from April to May, and fruit ripen from June to July (Corogin and Judd 2014, pp. 410-412). The plants can stand partial inundation with fresh water for a portion of the year, but do not tolerate salinity.

Fire Ecology and Demography

There have been no detailed studies of

Sideroxylon reclinatum

ssp.

austrofloridense

relationship towards fire; however, periodic fire is extremely important to maintaining habitat for this species (Corogin and Judd 2014, p. 414). Therefore, historical declines have been partially attributed to habitat loss from fire suppression or inadequate fire management (ENP 2014, p. 173).

Digitaria pauciflora (Florida pineland crabgrass)

Species Description

Digitaria pauciflora

is a small perennial clump-grass, appearing blue-green to gray with reddish-brown stems, typically 0.5-1 m (1.5-3 ft) tall (Small 1933, p. 51). The leaves form a subtle zig-zag pattern as the leaf blades come off the stem at an angle. The leaf blades are 7-18 cm (2.8-7.1) in) long, 1.0-2.2 mm (0.04-0.08 in) wide, and number 2-8 per stem. Both the lower and upper surface and stems are hairy but become glabrous (smooth or hairless) with age. The nodes are mostly glabrous, the sheath auricles (an ear-like projection at the base of the leaf) are 1.5 mm (0.06 in) long, and the sheaths are hairy but becoming glabrous with age. The ligule (a small bract located at the leaf-stem junction) is 1.5-2.0 mm (0.06-0.08 in) long. The flowers are dull green, very small, and are borne on wispy spikes on the ends of the leafy stems, with usually only a few flower clusters forming per clump of grass. The lemma (a tiny bract adjacent to the flower) of upper floret (flower) is purple. Stolons (aboveground horizontal stems) are not present, but the plant produces rhizomes (belowground horizontal stems) that allow for vegetative spread (Webster and Hatch, 1990, pp. 161-162).

Digitaria pauciflora

is known to reproduce sexually (Bradley and Gann 1999, p. 50), with fruit production in the fall (Wendelberger and Maschinski 2006, p. 3).

Taxonomy

Digitaria pauciflora

was first described in 1928 based on specimens collected in 1903 (Bradley and Gann 1999, p. 49). Small (1933, pp. 50-51) later placed it in the genus

Syntherisma.

Subsequent authors (Hitchcock 1935, p. 561; Webster & Hatch 1990, p. 161; Wunderlin 1998) have retained it in the genus

Digitaria

(Bradley and Gann 1999, p. 49).

The online Atlas of Florida Vascular Plants uses the name

Digitaria pauciflora

(Wunderlin and Hansen 2016, p. 1), the Integrated Taxonomic System (ITIS 2016, p. 1), NatureServe (2016, p. 1), and the Florida Department of Agriculture and Consumer Services (FDACS) (Coile and Garland 2003, p. 19) indicates that its taxonomic status is accepted. We have carefully reviewed all taxonomic data to determine that

Digitaria pauciflora

is a valid taxon. The only synonym is

Syntherisma pauciflora

(Hitchcock) Hitchcock ex Small (ITIS 2016, p. 1).

Climate

The climate of south Florida where

Digitaria pauciflora

occurs is classified as tropical savanna, as described above for

Sideroxylon reclinatum

ssp.

austrofloridense.

Habitat

Digitaria pauciflora

occurs predominantly within the seasonally flooded ecotone between pine rockland and marl prairie, although the species may overlap somewhat into both habitats (Bradley and Gann 1999, p. 49; Fellows

et al.

2002, p. 79). Plants can withstand inundation with fresh water for one to several months each year (ENP 2014, p. 172). These habitats are maintained by regular fire, and are prone, particularly marl prairie, to annual flooding for several months during the wet season (Gann

et al.

2006, p. 13). Pine rocklands and marl prairies are described in detail above for

Sideroxylon reclinatum

ssp.

austrofloridense.

Historical Range

All known historical and current records for

Digitaria pauciflora

are summarized in table 2. The historical range of

D. pauciflora

consists of central and southern Miami-Dade County along the Miami Rock Ridge, from the

southern Miami to Long Pine Key region of ENP, a range of approximately 42 mi (67.6 km) (Bradley and Gann 1999, p. 49). Specimens of

D. pauciflora

were collected early in the twentieth century throughout Miami-Dade County.

D. pauciflora

was absent from collections from 1939 until 1973, when it was rediscoverd at Long Pine Key in Everglades National Park (Bradley and Gann 1999, p. 49).

D. pauciflora

has subsequently been encountered consistently within Long Pine Key (Bradley and Gann 1999, p. 49).

A single

Digitaria pauciflora

plant was discovered in 1995 within marl prairie habitat at the Martinez Pinelands in the Richmond Pine Rocklands, an area of Miami-Dade County that retains the largest contiguous areas of pine rockland habitat outside of the Everglades. However, this plant has since disappeared (Herndon 1998, p. 88; Bradley and Gann 1999, p. 49; Gann 2015, p. 142). Three other historical occurrences in Miami-Dade County have been documented: (1) a site between Cutler and Longview Camp (last observed in 1903); (2) Jenkins Homestead (date unspecified); and (3) South Miami (last observed in 1939) (K. Bradley, pers. comm. 2007); however, little is known regarding the status of these populations. The species was not found during a 2-year project to survey and map rare and exotic plants along Florida Department of Transportation (FDOT) right-of-ways within Miami-Dade and Monroe Counties (Gordon

et al.

2007, pp. 1, 38).

Current Range, Population Estimates, and Status

The current range of

Digitaria pauciflora

includes ENP and BCNP (Bradley and Gann 1999, p. 49; Gann

et al.

2006, p. 3; Bradley, pers. comm. 2005a; Gann 2015, p. 142). Ongoing surveys suggest the species occurs throughout Long Pine Key of ENP (Gann

et al.

2006, p. 7; 2015, p. 144; Gann 2015, p. 144) and is much wider-ranging than previously known in ENP. Joyce Maschinski (FTBG, pers. comm. 2007) characterized the populations within ENP as abundant.

In 2002, Bradley

et al.

(2013, p. 2) discovered

Digitaria pauciflora

within the Lostmans Pines region of BCNP in Monroe County. This discovery represented the first known

D. pauciflora

occurrence outside Miami-Dade County (FNAI 2007, p. 191). The species is widely distributed within Lostmans Pines (Bradley

et al.

2013, pp. 1-8). Subsequent surveys for the species within BCNP have documented up to nine occurrences, some of which contain an estimated 500-600 plants (Maschinski

et al.

2003, p. 141). Bradley

et al.

(2013, pp. 1-8) conducted surveys in the Gum Slough region of Lostmans Pines and indicated that the species is widely distributed within the study area. A total of 2,365 plants was counted within pineland and sawgrass based survey plots (Bradley

et al.

2013, pp. 3-4). The range-wide population estimate for

D. pauciflora

is 1,000-10,000 individuals at Long Pine Key (Gann 2015, p. 142) and >10,000 individuals within BCNP (K. Bradley, pers. comm. 2007). Large-scale stochastic events such as wildfire and flooding can drastically reduce the size of

D. pauciflora

populations. For example, in the spring months of 2016, wildfires in areas occupied by

D. pauciflora

likely reduced populations in ENP. The populations will likely rebound; however, regeneration could be severely hampered, based on the amount and duration of flooding during the region's late summer storm season. While

Digitaria pauciflora

populations remain abundant within ENP and BCNP, these areas represent only half of the species' historical range (Bradley and Gann 1999, p. 25; Gann 2015, p. 167). While

D. pauciflora

was known to occur throughout Miami-Dade County, all other populations are likely extirpated.

Table 2—Summary of the Status and Trends of the Known Occurrences of

Digitaria Pauciflora

Population

Ownership

Most recent population

estimate

Status

Trend

Everglades National Park

National Park Service

1,000-10,000 (2007)

Extant

Stable.

Big Cypress National Preserve

National Park Service

>10,000 (2007)

Extant

Stable.

Martinez Pineland

Miami-Dade County

0 (1999)

Extirpated.

Cutler and Longview Camp

Unknown

Unknown (1903)

Extirpated.

Jenkins Homestead

Unknown

Unknown (date unspecified)

Extirpated.

South Miami

Unknown

Unknown (1939)

Extirpated.

Biology

Life History and Reproduction

Little is known about the life history of

Digitaria pauciflora,

including pollination biology, seed production, and dispersal. Reproduction is sexual, with new plants generated from seeds (Bradley and Gann, 1999, p. 53). The species produces flowers from summer to late fall on both new and older growth; some plants have been observed to finish seeding as late as December (Fellows

et al.

2002, p. 2; Gann 2015, p. 172). Plants can also spread clonally via rhizomes (Webster and Hatch, 1990, pp. 161-162). The plants can stand partial inundation with fresh water for a portion of the year, but do not tolerate salinity.

Fire Ecology and Demography

Digitaria pauciflora

population demographics and longevity have not been studied (Bradley and Gann, 1999, p. 53; Fellows

et al.

2002, p. 2). There have been no studies of the plant's relationship to fire; however, periodic fire is extremely important to maintaining habitat for this species (Bradley and Gann, 1999, p. 53; ENP 2014, p. 226). Therefore, historical declines have been partially attributed to habitat loss from fire suppression or inadequate fire management. Gann (2015, p. 142) indicates that the species shows patch dynamics, colonizing new areas and undergoing local extinctions with high rates of turnover. Plants with ‘flashy' or `boom and bust' demographic patterns are more susceptible to stochastic extinction events. ENP has burned populations of

D. pauciflora

during the wet and dry season, and both appear suitable to maintain populations of the plant (ENP 2014, p. 226).

Chamaesyce deltoidea spp. pinetorum (pineland sandmat)

Species Description

Chamaesyce deltoidea

ssp.

pinetorum

is an ascending to erect perennial herb. The stems are villous (hairy), and often reddish. The leaf blades range from kidney-shaped or triangle-shaped and elliptic to oval. The involucres (a cup-like structure enclosing the flowers) are 1 mm long, and pubescent, and possess green, even-edged glands with very narrow appendages. The fruit is a 2-mm broad, pubescent capsule. The seeds are 1 mm long, transversely wrinkled, and yellowish in color (Small 1933, p. 795).

C. deltoidea

ssp.

pinetorum

is known to reproduce sexually (Bradley and Gann 1999, p. 25). Fruit production is year-round, with a peak in the fall (Wendelberger and Maschinski 2006, p. 2).

Taxonomy

Chamaesyce deltoidea

ssp.

pinetorum

was first described by Small in 1905, based on specimens collected in eastern Miami-Dade County (Small 1905, pp. 429-430). Initially, Small referred to these specimens as

C. pinetorum

but recognized that it was closely related to

Chamaesyce deltoidea.

Herndon (1993, pp. 38-51) included

C. pinetorum

within the

C. deltoidea

complex, which is composed of three other taxa, two occurring further north on the Miami Rock Ridge, and one occurring on Big Pine Key in the lower Florida Keys (Monroe County). The three taxa on the Miami Rock Ridge have distinct, but adjacent ranges. Subsequently, Herndon (1993, pp. 38-51) has placed all four taxa at the same taxonomic level, treating each as a distinct subspecies under

Chamaesyce deltoidea

(

C. deltoidea

ssp.

pinetorum; C. deltoidea

ssp.

serpyllum, C. deltoidea

ssp.

adhaerens; C. deltoidea

ssp.

deltoidea

).

Chamaesyce deltoidea

ssp.

deltoidea

and

C. deltoidea

ssp.

adhaerens

occur north of known

C. deltoidea

ssp.

pinetorum

populations, while

Chamaesyce deltoidea

ssp.

serpyllum

is endemic to Big Pine Key. Wunderlin and Hansen (2016, p. 1) follow Herndon's treatment in using

C. deltoidea

ssp.

pinetorum.

Some modern authors place the genus

Chamaesyce

into the genus

Euphorbia sensu lato

(Yang and Berry 2011, pp. 1486-1503). Gann (2015, p. 168) indicates that if the pineland sandmat is placed into the genus

Euphorbia,

the correct name is

Euphorbia deltoidea

ssp.

pinetorum.

The online Atlas of Florida Vascular Plants uses the name

Chamaesyce deltoidea

ssp.

pinetorum

(Small) Herndon (Wunderlin and Hansen 2016, p. 1). NatureServe (2016, p. 1) and FDACS (Coile and Garland 2003, p. 11) indicate that

C. deltoidea

ssp.

pinetorum

is accepted. However, the Integrated Taxonomic System (ITIS 2016, p. 1) accepts

Euphorbia deltoidea

ssp.

pinetorum

as the scientific name for the species (Gann 2015, p. 168). We have carefully reviewed all taxonomic data and have determined that

C. deltoidea

ssp.

pinetorum

is a valid taxon.

Climate

The climate of south Florida where

Chamaesyce deltoidea

ssp.

pinetorum

occurs is classified as tropical savanna, as described above for

Sideroxylon reclinatum

ssp.

austrofloridense.

Habitat

Chamaesyce deltoidea

ssp.

pinetorum

occurs in pine rocklands (Bradley and Gann 1999, p. 24). Pine rocklands are maintained by regular fire, and are prone to annual flooding for several months during the wet season (Gann

et al.

2006, p. 13). However, Gann (2015, p. 169), indicates that

C. deltoidea

ssp.

pinetorum

generally occurs in higher elevation pine rocklands at Long Pine Key in ENP, in areas rarely subject to flooding. Pine rockland habitat is described in detail above in the Habitat section for

Sideroxylon reclinatum

ssp.

austrofloridense.

Historical Range

All known historical and current records for

Chamaesyce deltoidea

ssp.

pinetorum

are summarized in table 3.

Chamaesyce deltoidea

ssp.

pinetorum

occurred historically only within the southern portion of the Miami Rock Ridge, from the Richmond Pine Rocklands of southern Miami to the Long Pine Key region of Everglades National Park, a range of approximately 42 mi (67.6 km) (Bradley and Gann 1999, p. 24).

C. deltoidea

ssp.

pinetorum

has been encountered consistently within Long Pine Key, as well as in several County-owned conservation lands adjacent to the ENP (Gann 2015, p. 167).

Current Range, Population Estimates, and Status

The current range of

Chamaesyce deltoidea

ssp.

pinetorum

is similar to the historical range, although 98 percent of the pine rocklands (the species' only habitat) outside of the ENP has been lost to development (Kernan and Bradley 1996, p. 2). The total population size of

Chamaesyce deltoidea

ssp.

pinetorum

is estimated to be between 14,500-146,000 individuals, with the majority of the population occurring on Long Pine Key (Bradley and Gann 1999, p. 25; Gann 2015, p. 167). However, while

Chamaesyce deltoidea

ssp.

pinetorum

is most abundant within ENP, pine rockland fragments outside of the Everglades represent about half the species' extant range (Bradley and Gann 1999, p. 25; Bradley pers. comm. 2007; Gann 2015, p. 167). Elsewhere in Miami-Dade County, a 2011 survey of the privately owned Pine Ridge Sanctuary confirmed the plant remains at this site (FNAI 2011, p. 5). A recent survey of Larry and Penny Thompson Park located no individuals (J. Possley, FTBG, pers. comm. 2011c).

Table 3—Summary of the Status and Trends of the Known Occurrences of Chamaesyce deltoidea ssp. pinetorum

Population

Ownderhip

Most recent population

estimate

Status

Trend

Everglades National Park

National Park Service

10,000-100,000 (2011)

Extant

Increasing.

Florida City Pineland

Miami-Dade County

100-1,000 (2007)

Extant

Increasing.

Navy Wells

Miami-Dade County

1,000-10,000 (2007)

Extant

Insufficient data.

Navy Wells #2

Miami-Dade County

100-1,000 (2007)

Extant

Insufficient data.

Navy Wells #39

Miami-Dade County

1,000-10,000 (2007)

Extant

Insufficient data.

Palm Drive Pineland

Miami-Dade County

10-100 (2007)

Extant

Insufficient data.

Pine Ridge Sanctuary

Private

10-100 (2011)

Extant

Insufficient data.

Rock Pit #39

Miami-Dade County

11-1,000 (2007)

Extant

Insufficient data.

Seminole Wayside Park

Miami-Dade County

100-1,000 (2007)

Extant

Insufficient data.

Fuchs Hammock Addition

Miami-Dade County

11-100 (2007)

Extant

Insufficient data.

Sunny Palms Pineland

Miami-Dade County

100-1,000 (2007)

Extant

Insufficient data.

Larry and Penny Thompson Park

Miami-Dade County

0 (2011)

Extirpated

Insufficient data.

John Kunkel Small Pineland

Institute for Regional Conservation

Present (2006)

Extant

Insufficient data.

Natural Forest Community [NFC] #P330

Private

11-100 (2007)

Extant

Insufficient data.

Natural Forest Community #P338

Private

1,001-10,000 (2007)

Extant

Insufficient data.

Natural Forest Community #P339

Private

11-100 (2007)

Extant

Insufficient data.

Natural Forest Community #P347

Private

11-100 (2007)

Extant

Insufficient data.

Natural Forest Community #P411

Private

101-1,000 (2007)

Extant

Insufficient data.

Natural Forest Community #P413

Private

11-100 (2007)

Extant

Insufficient data.

Natural Forest Community #P416

Private

11-100 (2007)

Extant

Insufficient data.

Natural Forest Community #P445

Private

1,001-10,000 (2007)

Extant

Insufficient data.

Biology

Life History and Reproduction

Little is known about the life history of

Chamaesyce deltoidea

ssp.

pinetorum.

Reproduction is sexual, but little is known about the reproductive biology and ecology of the species (Bradley and Gann 1999, p. 25; Gann 2015, p. 167). Herndon (1998, pp. 13-14) studied the life history and population trends of

C. deltoidea

ssp.

pinetorum

and found up to 88 percent of plants survived more than 3 years, showing that it is a somewhat long-lived taxon. Herndon (1998, pp. 13-14) hypothesized that some of the plants that had been recorded as dead may have instead been in a cryptic phase (Gann 2015, p. 167). The extensive root system of

C. deltoidea

ssp.

pinetorum

also suggests that it is a long-lived plant (Maschinski

et al.

2003, p. 179). Pollinators are unknown; other species of

Chamaesyce

are completely reliant on insects for pollination and seed production, while others are self-pollinating (Maschinski

et al.

2003, p. 179; Gann 2015, p. 168). Pollinators may include bees, flies, ants, and wasps (Ehrenfeld 1979, p. 95; Gann 2015, p. 168). Dispersal is unknown for

Chamaesyce deltoidea

ssp.

pinetorum;

however, many seed capsules in similar

Chamaesyce

species are explosively dehiscent, a form of dispersal that flings seeds far from the parent plant (Maschinski

et al.,

p. 179; Gann 2015, p. 168). This species is known to flower and fruit year round (Wendelberger and Maschinski 2006, p. 2). Peaks in fruiting for

C. deltoidea

ssp.

pinetorum

occur in the fall and are stimulated by fire (Wendelberger and Maschinski 2006, p. 2). The plants can stand partial inundation with fresh water for a portion of the year, but do not tolerate salinity.

Fire Ecology and Demography

There have been no studies of

Chamaesyce deltoidea

ssp.

pinetorum

population demographics. However, the species is not shade tolerant, and it requires periodic low-intensity fires to reduce competition by woody species to maintain habitat for this species (Bradley and Gann, 1999, p. 26; ENP 2014, p. 170). Therefore, historical declines have been partially attributed to habitat loss from fire suppression or inadequate fire management.

Dalea carthagenensis var. floridana (Florida prairie-clover)

Species Description

Dalea carthagenensis

var.

floridana

is a short-lived (less than 7 years) perennial shrub 2.6-9.8 ft (0.8-3.0 m) tall with a light-brown woody stem and non-woody, light-brown or reddish branches. The leaves are composed of 9-15 oval, gland-tipped leaflets, and are gland-dotted on the underside. The flowers are in small loose heads at ends of hairy, glandular stalks, less than 0.4 in long. The flower color is white and maroon; each of the petals is different lengths and shapes. The fruit is a small one-seeded pod, mostly enclosed by the hairy, gland-dotted calyx (bracts at base of each flower) (adapted from Long and Lakela 1971, p. 478; Bradley and Gann 1999, p. 42; Maschinski

et al.

2014, p. 44).

Taxonomy

Chapman (1886, p. 102) was the first to report this taxon in Florida, calling it the tropical

Dalea domingensis,

based on specimens collected on Key Biscayne. Small (1913, p. 89) accepted this characterization but included the taxon in the genus

Parosela,

making the plant

P. domingensis.

Rydberg (1920, p. x) renamed the plant, calling it

Parosela floridana,

and this name was retained by Small (1933, pp. 694-695). Clausen (1946a, p. 85) reviewed the taxonomy of Florida and West Indian

Dalea

and considered them all to be the same species. Clausen (1946a, p. 85) also found that the name

D. domingensis

was a homonym of

D. emphysodes,

and published the name

D. emphysodes

ssp.

domingensis.

Clausen (1946b, p. 572) later discovered that his use of the name

D. emphysodes

was in error, and renamed the plants

D. carthagenensis

ssp.

domingensis.

Long and Lakela (1971, p. 478) accepted this usage. Barneby (1977), in a monograph of the genus, also found that Florida plants were distinct from West Indian plants, citing differences in leaf characters, naming the Florida species

D. carthagenensis

var.

floridana.

Wunderlin (1998) has followed this treatment.

The Integrated Taxonomic Information System (2016, p. 1) indicates that the taxonomic standing for

Dalea carthagenensis

var.

floridana

(Rydb.) Barneby is accepted. The online Atlas of Florida Vascular Plants (Wunderlin and Hansen 2016, p. 1) uses the name

D. carthagenensis

var.

floridana,

as does NatureServe (2016, p. 1). FDACS uses the name

Dalea carthagenensis

and notes that

D. carthagenensis

var.

floridana

is endemic (Coile and Garland 2003, p. 17). In summary, there is consensus that

D. carthagenensis

var.

floridana

is a distinct taxon. We have carefully reviewed the available taxonomic information to reach the conclusion that

D. carthagenensis

var.

floridana

is a valid taxon.

Climate

The climate of south Florida where

Dalea carthagenensis

var.

floridana

occurs is classified as tropical savanna

as described above for

Sideroxylon reclinatum

ssp.

austrofloridense.

Habitat

Dalea carthagenensis

var.

floridana

grows in pine rockland, rockland hammock, marl prairie, coastal berm, and in the ecotones between these habitats (Bradley and Gann 1999, p. 43). The species may also occur along roadsides within these habitats (Gann

et al.

2006, p. 10). Pine rockland and marl prairie habitat are described in detail above in the Habitat section for

Sideroxylon reclinatum

ssp.

austrofloridense.

Roadsides

Roadsides are a potentially important habitat for

Dalea carthagenensis

var.

floridana

(Bradley and Gann 1999, p. 43). Where endemics such as

D. carthagenensis

var.

floridana

are found on shoulders, the ground cover is dominated mostly by native herbs and grasses where exotic lawn grasses have not been planted. Maintaining the roadsides in this condition through regular mowing, without planting sod, should continue to provide suitable habitat for

Dalea carthagenensis

var.

floridana

(Bradley 2006, p. 37).

Rockland Hammock

Rockland hammock is a species-rich tropical hardwood forest on upland sites in areas where limestone is very near the surface and often exposed. The forest floor is largely covered by leaf litter with varying amounts of exposed limestone and has few herbaceous species. Rockland hammocks typically have larger, more mature trees in the interior, while the margins can be almost impenetrable in places with dense growth of smaller shrubs, trees, and vines. Typical canopy and subcanopy species include

Bursera simaruba, Lysiloma latisiliquum

(false tamarind),

Coccoloba diversifolia

(pigeon plum),

Sideroxylon foetidissimum

(false mastic),

Ficus aurea

(strangler fig),

Piscidia piscipula

(Jamaican dogwood),

Ocotea coriacea

(lancewood),

Drypetes diversifolia, Simarouba glauca

(paradisetree),

Sideroxylon salicifolium

(willow bustic),

Krugiodendron ferreum

(black ironwood),

Exothea paniculata

(inkwood),

Metopium toxiferum,

and

Swietenia mahagoni

(West Indies mahogany). Mature hammocks may be open beneath a tall, well-defined canopy and subcanopy. More commonly, in less mature or disturbed hammocks, dense woody vegetation of varying heights from canopy to short shrubs is often present. Species that generally make up the shrub layers within rockland hammock include several species of

Eugenia

(stoppers),

Thrinax morrisii

and

T. radiata

(thatch palms),

Amyris elemifera

(sea torchwood),

Ardisia escallonioides

(marlberry),

Psychotria nervosa

(wild coffee),

Chrysophyllum oliviforme

(satinleaf),

Sabal palmetto

(cabbage palm),

Guaiacum sanctum

(lignum-vitae),

Ximenia americana

(tallow wood),

Colubrina elliptica

(soldierwood),

Pithecellobium unguis-cati

(cat claw blackbead) and

Pithecellobium keyense

(Florida keys blackbead),

Coccoloba uvifera

(sea grape), and

Colubrina arborescens

(greenheart). Vines can be common and include

Toxicodendron radicans

(eastern poison ivy),

Smilax auriculata

(earleaf greenbrier),

Smilax havanensis

(Everglades greenbrier),

Parthenocissus quinquefolia

(Virginia creeper),

Hippocratea volubilis

(medicine vine), and

Morinda royoc

(redgal). The typically sparse, short shrub layer may include

Zamia pumila

(coontie) and

Acanthocereus tetragonus

(triangle cactus). Herbaceous species are occasionally present and generally sparse in coverage. Characteristic species include

Lasiacis divaricata

(smallcane),

Oplismenus hirtellus

(basketgrass), and many species of ferns (FNAI 2010, p. 24).

Rockland hammock occurs on a thin layer of highly organic soil covering limestone on high ground that does not regularly flood, but it is often dependent upon a high water table to keep humidity levels high. Rockland hammocks are frequently located near wetlands; in the Everglades they can occur on organic matter that accumulates on top of the underlying limestone (FNAI 2010, p. 25).

Rockland hammock is susceptible to fire, frost, canopy disruption, and ground water reduction. Rockland hammock can be the advanced successional stage of pine rockland, especially in cases where rockland hammock is adjacent to pine rockland. In such cases, when fire is excluded from pine rockland for 15 to 25 years, it can succeed to rockland hammock vegetation. Historically, rockland hammocks in south Florida evolved with fire in the landscape. Fire most often extinguished near the edges when it encountered the hammock's moist microclimate and litter layer. However, rockland hammocks are susceptible to damage from fire during extreme drought or when the water table is lowered. In these cases, fire can cause tree mortality and consume the organic soil layer (FNAI 2010, p. 25).

Rockland hammocks are also sensitive to the strong winds and storm surge associated with infrequent hurricanes. Canopy damage often occurs, which causes a change in the microclimate of the hammock. Decreased relative humidity and drier soils can leave rockland hammocks more susceptible to fire. Rockland hammock can transition into glades marsh, mangrove swamp, salt marsh, coastal rock barren, pine rockland, maritime hammock, or marl prairie (FNAI 2010, p. 26).

The sparsely vegetated edges or interior portions laid open by canopy disruption are the areas of rockland hammock that have light levels sufficient to support

Dalea carthagenensis

var.

floridana.

However, the dynamic nature of the habitat means that areas not currently open may become open in the future as a result of canopy disruption from hurricanes, while areas currently open may develop more dense canopy over time, eventually rendering that portion of the hammock unsuitable for

Dalea carthagenensis

var.

floridana.

Coastal Berm

Coastal berms are landscape features found along low-energy coastlines in south Florida and the Florida Keys. Coastal berm is a short forest or shrub thicket found on long, narrow, storm-deposited ridges of loose sediment formed by a mixture of coarse shell fragments, pieces of coralline algae, and other coastal debris. These ridges parallel the shore and may be found on the seaward edge or landward edge of the mangroves or farther inland depending on the height of the storm surge that formed them. They range in height from 0.30 to 3.05 m (1 to 10 ft). Structure and composition of the vegetation is variable depending on height and time since the last storm event. The most stable berms may share some tree species with rockland hammocks, but generally have a greater proportion of shrubs and herbs. Tree species may include

Bursera simaruba

(gumbo limbo),

Coccoloba uvifera

(seagrape),

Coccothrinax argentata

(silver palm),

Guapira discolor

(blolly),

Drypetes diversifolia

(milkbark),

Genipa clusiifolia

(seven year apple), and

Metopium toxiferum

(poisonwood). Characteristic tall shrub and short tree species include

Eugenia foetida

(Spanish stopper),

Ximenia americana

(hog plum),

Randia aculeata

(white indigoberry),

Pithecellobium keyense

(Florida Keys blackbead), and

Sideroxylon celastrinum

(saffron plum). Short shrubs and herbs include

Hymenocallis latifolia

(perfumed spiderlily),

Capparis flexuosa

(bayleaf capertree),

Lantana involucrata

(buttonsage), and

Rivina humilis

(rougeplant). More seaward berms or those more recently affected by storm deposition may support a suite of plants similar to beaches, including shoreline

Sesuvium portulacastrum

(sea purslane),

Distichlis spicata

(saltgrass), and

Sporobolus virginicus

(seashore dropseed), or scattered to dense shrub thickets with

Conocarpus erectus

(buttonwood), stunted

Avicennia germinans

(black mangrove),

Rhizophora mangle

(red mangrove),

Laguncularia racemosa

(white mangrove),

Suriana maritima

(bay cedar),

Manilkara jaimiqui

(wild dilly),

Jacquinia keyensis

(joewood), and

Borrichia frutescens

(bushy seaside oxeye) (Florida Natural Areas Inventory (FNAI) 2010a, p. 1).

Coastal berms are deposited by storm waves along low-energy coasts. Their distance inland depends on the height of the storm surge. Tall berms may be the product of repeated storm deposition. Coastal berms that are deposited far enough inland and remain long-undisturbed may in time succeed to hammock. This is a structurally variable community that may appear in various stages of succession following storm disturbance, from scattered herbaceous beach-colonizing plants to a dense stand of tall shrubs (FNAI 2010a, p. 2).

Historical Range

All known historical and current records for

Dalea carthagenensis

var.

floridana

are summarized in table 4. The historical range of

D. carthagenensis

var.

floridana

includes Miami-Dade, Monroe, Collier, and Palm Beach Counties (Gann

et al.

2015, pp. 25-26). There have been no reports of this plant from Palm Beach County since 1918 (Bradley and Gann 1999, p. 42). In Miami-Dade County, the species has been extirpated from a number of historical locations, including Castellow Hammock, ENP, the Coral Gables area, pinelands south of the Miami River, and Cox Hammock (Bradley and Gann 1999, pp. 42-43; Maschinski

et al.

2014, p. 39). Gann

et al.

(2002, pp. 408-411) accounted for essentially every herbarium specimen and reliable sighting. Gann (2015, pp. 25-26) did not find

D. carthagenensis

var.

floridana

in ENP, and it is presumed to be extirpated at this location. One of the previous records at ENP was originally misidentified and has recently been confirmed as a specimen of

Aeschynomene pratensis

(J. Sadle, NPS, pers. comm. 2014). The other ENP herbarium specimen was correctly identified, but the plant is currently considered to be extirpated from the historical location (J. Sadle, NPS, pers. comm. 2014).

Current Range, Population Estimates, and Status

The current range of

Dalea carthagenensis

var.

floridana

includes BCNP (Monroe and Collier Counties), three Miami-Dade County conservation areas, and three unprotected lands within the Cutler Bay region of Miami-Dade County (Maschinski

et al.

2014, p. 39)

In 1999,

Dalea carthagenensis

var.

floridana

was rediscovered within BCNP (Bradley and Gann 1999, p. 42). Maschinski

et al.

(2014, p. 31) subsequently surveyed the four extant populations on BCNP, finding them at two locations. An area north of Oasis Visitor Center contained 236 plants (of various ages) and represents the largest extant population within BCNP. The second extant population was in the Pinecrest region (along Loop Road) of BCNP, an historic location within the Park; however, only 17 plants were encountered. The species was not found at 11-Mile Road, or at a second location along Loop Road during the surveys.

Maschinski

et al.

(2014, pp. 31-34) have extensively surveyed extant

Dalea carthagenensis

var.

floridana

populations at Charles Deering Estate, R. Hardy Matheson Preserve, and Crandon Park within Miami-Dade County over the past decade.

During 2003 to 2007, the population at Charles Deering Estate ranged from between 50 and 80 individuals, with the number of seedlings ranging from 3 to 54. However, beginning in 2008, Maschinski

et al.

(2014, p. 33) have documented pulses in seedling establishment. In 2010, the total population size (seedlings and woody plants) was 356 individuals. The majority of these were seedlings and basal re-sprouts from a fire that affected approximately one-third of the population (Maschinski

et al.

2010, p. 24). A 2014 survey found 347 plants, suggesting the population remains stable (Maschinski

et al.

2015, p. 30).

The population at R. Hardy Matheson Preserve had declined from 31 plants in 2004 to just 1 woody plant and 3 seedlings in 2008. However, the population increased to 330 and 200 seedlings in 2009 and 2010, respectively. The most recent surveys indicated stable populations of 98 and 307 individuals, in 2014 and 2015, respectively (Maschinski

et al.

2010, p. 30; 2014, p. 34).

In 2003,

Dalea carthagenensis

var.

floridana

was discovered within coastal uplands at Crandon Park for the first time since 1966 (Maschinski

et al.

2010, p. 28). The population at Crandon Park appears to be stable; however, it is highly localized to a small area of approximately 145 m

2

(Possley and Maschinski 2009, p. 10). During 2007, FTBG initiated a demographic study of the species. Sampling plots found 200 plants of various sizes, resulting in a population estimate of 966 plants at the site (J. Maschinski, pers. comm. 2007; Possley and Maschinski 2009, p. 10). Subsequent surveys have shown the population to vary considerably, possibly due to a short lifespan or plant dormancy (Possley and Maschinski 2009, p. 10). Surveys at Crandon Park identified 288 and 168 individuals, in 2014 and 2015, respectively (Maschinski

et al.

2015, p. 32). Additional known populations within Miami-Dade County are summarized in table 4.

Table 4—Summary of the Status and Trends of the Known Occurrences of Dalea carthagenensis var. floridana

Population

Ownership

Most recent population

estimate

Status

Trend

Everglades National Park

National Park Service

Extirpated (1964).

Big Cypress National Preserve, North of Oasis Visitor Center

National Park Service

236 (2013)

Extant

Insufficient data.

Big Cypress National Preserve, 11-Mile Road

National Park Service

0 (2013)

Extirpated (2014)

Insufficient data.

Big Cypress National Preserve, Pinecrest

National Park Service

17 (2013)

Extant

Insufficient data.

Charles Deering Estate

Miami-Dade County

347 (2014)

Extant

Stable.

Virginia Key (reintroduction)

City of Miami

4 (2010)

Extant

Insufficient data.

R. Hardy Matheson Preserve

Miami-Dade County

307 (2015)

Extant

Stable.

Crandon Park

Miami-Dade County

168 (2015)

Extant

Stable.

Strawberry Fields Hammock (next to Natural Forest Community)

Private

17 (2014)

Extant

Insufficient data.

HRS, Inc.

Private

21 (2014)

Extant

Insufficient data.

Florida Power and Light property

Florida Power and Light

2-10 (2007)

Extant

Insufficient data.

Coral Gables area

Private

Extirpated (1967).

Cox Hammock

Private

Extirpated (1930).

Castellow Hammock Preserve

Miami-Dade County

Extirpated (1975).

Pineland South of Miami River

Unknown

Unknown

Unknown.

Palm Beach County

Private

Extirpated (1918).

Biology

Life History and Reproduction

Dalea carthagenensis

var.

floridana

appears to be a short-lived (less than 7 years) perennial with a persistent seed bank (Maschinski

et al.

2014, p. 45). The species produces flowers from October to March, and fruit ripen from November to April. The seed maturation period is January to May, with a peak in February and March. Larger plants can produce more than 500 seeds. Seedling recruitment varies widely from year to year, with lower recruitment in drier years. Seedlings and juveniles experience rapid growth in their first 2 years (Maschinski

et al.

2014, p. 45). The plants can stand partial inundation with fresh water for a portion of the year, but do not tolerate salinity.

Maschinski

et al.

(2014, p. 41) used ongoing survey data from the Crandon Park population to conduct a preliminary population viability analysis (PVA). The population at Crandon Park declined by 33 percent from 2007 to 2009. High seedling recruitment increased numbers in 2010, which stabilized the population until 2014, when a pulse of high recruitment occurred. The demographic study indicated that 3 years had declining population growth and 4 years were stable or increasing, a cyclic pattern characteristic of short-lived species. The PVA indicated that the external cues (temperature and soil moisture) required to break dormancy positively influenced

Dalea carthagenensis

var.

floridana

population dynamics. However, if coupled with seedling mortality, serious population decline resulted. Low winter temperature coupled with average rainfall resulted in high seedling recruitment and good seedling survival; however, if high rainfall followed cold winter temperatures, as was noted for winter 2010, seedling mortality was high (Maschinski

et al.

2014, p. 41).

Fire Ecology and Demography

There have been no studies of

Dalea carthagenensis

var.

floridana

relationship to fire; however, periodic fire is extremely important to maintaining habitat for this species (Maschinski

et al.

2014, p. 47). Therefore, historical declines have been partially attributed to habitat loss from fire suppression or inadequate fire management.

Summary of Biological Status and Threats

The Act directs us to determine whether any species is an endangered species or a threatened species because of any factors affecting its continued existence. In this section, we summarize the biological condition of each of the plant species and its resources, and the influences on such, to assess the species' overall viability and the risks to that viability.

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

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

have experienced substantial destruction, modification, and curtailment of their habitat and range (see Background, above). Specific threats to these plants included in this factor include habitat loss, fragmentation, and modification caused by development (

i.e.,

conversion to both urban and agricultural land uses) and inadequate fire management. Each of these threats and its specific effects on these plants are discussed in detail below.

Human Population Growth, Development, and Agricultural Conversion

The modification and destruction of the habitats that support

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

has been extreme in most areas of Miami-Dade and Monroe Counties, thereby reducing the plants' current range and abundance in Florida. The pine rockland community of south Florida, in which these species primarily occur, is critically imperiled locally and globally (FNAI 2010, p. 62). Destruction of pine rocklands and rockland hammocks has occurred since the beginning of the 1900s. Extensive land-clearing for human population growth, development, and agriculture in Miami-Dade and Monroe Counties has altered, degraded, or destroyed thousands of acres of these once-abundant ecosystems.

In Miami-Dade County, development and agriculture have reduced pine rockland habitat by 90 percent in mainland south Florida. Pine rockland habitat in Miami-Dade County, including ENP, was reduced to about 11 percent of its natural extent, from approximately 74,000 ha (183,000 ac) in the early 1900s, to only 8,140 ha (20,100 ac) in 1996 (Kernan and Bradley 1996, p. 2). The largest remaining intact pine rockland (approximately 2,313 ha (5,716

ac)) is Long Pine Key in ENP. Outside of ENP, only about 1 percent of the pine rocklands on the Miami Rock Ridge have escaped clearing, and much of what is left are small remnants scattered throughout the Miami metropolitan area, isolated from other natural areas (Herndon 1998, p. 1). Habitat loss continues to occur in these plants' range, and most remaining suitable habitat has been negatively altered through human activity (illegal clearing, dumping), preclusion of fire, and introduction of nonnative species.

Significant remaining pine rockland habitat occurs on private lands and publicly owned lands that are not dedicated to or managed for conservation. Species occurrences and suitable habitat remaining on these lands are threatened by habitat loss and degradation, and threats are expected to accelerate with increased development. The human population within Miami-Dade County is currently greater than 2.4 million people, and the population is expected to grow to more than 4 million by 2060, an annual increase of roughly 30,000 people (Zwick and Carr 2006, p. 20). Some of the known populations of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

occur on public conservation lands. Miami-Dade County has developed a network of publicly owned conservation lands within Miami-Dade County, but prescribed fire is lacking at many of these sites. ENP and BCNP actively manage their respective pine rockland habitat with prescribed fire (tables 1-4). However, any extant populations of these plants or suitable habitat that may occur on non-conservation public or private land, such as within the Richmond Pine Rocklands, are vulnerable to habitat loss directly from development or indirectly by lack of management.

The marl prairie habitat that also supports

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

has similarly been destroyed by the rapid development of Miami-Dade and Monroe Counties. At least some of the occurrences reported from this habitat may be the result of colonization that occurred after the habitat was artificially dried-out due to local or regional drainage. Marl prairie on non-conservation public or private land remains vulnerable to development, which could lead to the loss of populations of the species.

Sideroxylon reclinatum

ssp.

austrofloridense

occurs in numerous pine rocklands outside of ENP within Miami-Dade County, most of which are impacted be some degree by development. Two privately owned sites in Miami-Dade County supporting

Sideroxylon reclinatum

ssp.

austrofloridense

are vulnerable to habitat loss from development. Eight sites that support the species are public land, which provides for some management and protection. However, one population on public land, the county-owned Nixon-Smiley Preserve, is extirpated due to inadequate management.

Both extant populations of

Digitaria pauciflora

are located at ENP and BCNP, which are public lands managed for conservation. However,

D. pauciflora

is extirpated from four sites outside ENP and BCNP, which comprise half of the species' historical range (Bradley and Gann 1999, p. 25; Gann 2015, p. 167). Outside the protected lands of ENP and BCNP,

Digitaria pauciflora

occurred throughout Miami-Dade County, including as recently as 1995 within the pine rockland and marl prairie habitats of the Martinez Pineland. Martinez Pineland is adjacent to several other remnant pine rocklands that form the largest contiguous area of pine rockland habitat in Miami-Dade County. However,

D. pauciflora

has since disappeared (Herndon 1998, p. 88; Bradley and Gann 1999, p. 49) from Martinez Pineland, and plans are being reviewed for development of private portions (see discussion of Richmond Pine Rocklands, below). Gordon

et al.

(2007, pp. 1, 38) did not document other extant

D. pauciflora

populations during surveys to map rare and exotic plants along FDOT right-of-ways within Miami-Dade and Monroe Counties. Three other historical occurrences in Miami-Dade County had been documented; however, no population estimates were made prior to these areas being destroyed by habitat loss.

Eight populations of

Chamaesyce deltoidea

ssp.

pinetorum

located on private land are vulnerable to habitat loss due to development. Ten extant populations occur on public land and are largely protected from development. A historical population of

Chamaesyce deltoidea

ssp.

pinetorum

within Larry and Penny Thompson Park (also part of the Richmond Pine Rocklands) has been extirpated due to lack of prescribed fire (J. Possley, FTBG, pers. comm. 2011).

Dalea carthagenensis

var.

floridana

has been extirpated from a number of historical locations within Miami-Dade County, including ENP for unknown reasons, and by development at Castellow Hammock, in the Coral Gables area, the pinelands south of the Miami River, and Cox Hammock (Bradley and Gann 1999, pp. 42-43; Maschinski

et al.

2014, p. 39). In addition, there have been no reports of this species from Palm Beach County since 1918, and this area is now densely developed (Bradley and Gann 1999, p. 42). Six populations occur on public lands and are protected from development. Three extant populations occur on private land and are vulnerable to habitat loss from development.

Currently, there are plans to develop 55 ha (137 ac) of the largest remaining parcel of pine rockland habitat in Miami-Dade County, the Richmond Pine Rocklands, with a shopping center and residential construction (Ram 2014, p. 2). Bradley and Gann (1999, p. 4) called the 345-ha (853-ac) Richmond Pine Rocklands, “the largest and most important area of pine rockland in Miami-Dade County outside of Everglades National Park.” Although both

Digitaria pauciflora

and

Chamaesyce deltoidea

ssp.

pinetorum

have been extirpated from Richmond Pine Rocklands, populations of

Sideroxylon reclinatum

ssp.

Austrofloridense,

along with numerous other federally listed species, still occur there.

The Miami-Dade County Department of Environmental Resources Management has completed a management plan for portions of the Richmond Pine Rocklands under a grant from the Service and is leading the restoration and management of the Richmond Pine Rocklands (Bradley and Gann 1999, p. 4). The developer has proposed to enter into a Habitat Conservation Plan in conjunction with their plans to develop their portion of the site and was required by Miami-Dade County Natural Forest Community (NFC) regulations to set aside and manage 17 ha (43 ac) of pine rockland and associated habitats. A second project that would result in the loss of pine rockland habitat has been proposed for the Richmond Pine Rocklands. It includes expanding the Miami Zoo complex to develop an amusement park and commercial entities. These development projects will result in the loss of pine rockland habitat that maintains a population of

Sideroxylon reclinatum

ssp.

austrofloridense

as well as several federally listed species, and may preclude future recovery options for the four plants (such as compromising the land managers ability to burn within Richmond Pine Rocklands).

Habitat Fragmentation

The remaining pine rocklands in the Miami metropolitan area are severely

fragmented and isolated from each other. Habitat fragmentation reduces the size of plant populations, and increases spatial isolation of remnants. Barrios

et al.

(2011, p. 1062) investigated the effects of fragmentation on a threatened pine rockland plant,

Angadenia berteroi

(pineland golden trumpet), and found that abundance and fragment size were positively related. Possley

et al.

(2008, p. 385) studied the effects of fragment size on species composition in south Florida pine rocklands, and found that plant species richness and fragment size were positively correlated (although some small fragments supported nearly as many species as the largest fragment). Composition of fragmented habitat typically differs from that of intact forests, as isolation and edge effects increase leading to increased abundance of disturbance-adapted species (weedy species, nonnative invasive species) and lower rates of pollination and propagule dispersal (Laurence and Bierregaard 1997, pp. 347-350.; Noss and Csuti 1997, pp. 284-299).

The degree to which fragmentation threatens the dispersal abilities of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

is unknown. In the historical landscape, where pine rockland occurred within a mosaic of wetlands, water may have acted as a dispersal vector for all pine rockland seeds. In the current fragmented landscape, this type of dispersal would no longer be possible for any of the Miami-Dade populations, because they exist in isolated habitat patches surrounded by miles of unsuitable habitat (agriculture and urban development) on every side. While additional dispersal vectors may include animals and (in certain locations) mowing equipment, it is likely that fragmentation has effectively reduced these plants' ability to disperse.

While pollination research has not been conducted for

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana,

research regarding other species and ecosystems provides valuable information regarding potential effects of fragmentation to these plants. Effects of fragmentation may include changes to the pollinator community as a result of limitation of pollinator-required resources (

e.g.,

reduced availability of rendezvous plants, nesting and roosting sites, and nectar/pollen); these changes may include changes to pollinator community composition, species abundance and diversity, and pollinator behavior (Rathcke and Jules 1993, pp. 273-275; Kremen and Ricketts 2000, p. 1227; Harris and Johnson 2004, pp. 30-33). As a result, plants in fragmented habitats may experience lower visitation rates, which in turn may result in reduced seed production of the pollinated plant (which may lead to reduced seedling recruitment), reduced pollen dispersal, increased inbreeding, reduced genetic variability, and ultimately reduced population viability (Rathcke and Jules 1993, p. 275; Goverde

et al.

2002, pp. 297-298; Harris and Johnson 2004, pp. 33-34).

The effects of fragmentation on fire go beyond edge effects and include reduced likelihood and extent of fires, and altered behavior and characteristics (

e.g.,

intensity) of those fires that do occur. Habitat fragmentation encourages the suppression of naturally occurring fires, and has prevented fire from moving across the landscape in a natural way, resulting in an increased amount of habitat suffering from these negative impacts. High fragmentation of small habitat patches within an urban matrix discourages the use of prescribed fire as well due to logistical difficulties (see Fire Management, below).

Forest fragments in urban settings are also subject to increased likelihood of certain types of human-related disturbance, such as the dumping of trash (Chavez and Tynon 2000, p. 405) and illegal clearing. The many effects of habitat fragmentation may work in concert to threaten the local persistence of a species, especially of small populations (see discussion below); when a species' range of occurrence is limited, as with these four plants, threats to local persistence increase extinction risk.

Fire Management

One of the primary threats to

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

is habitat modification and degradation through inadequate fire management, which includes both the lack of prescribed fire and suppression of natural fires. Where the term “fire-suppressed” is used below, it describes degraded pine rockland conditions resulting from a lack of adequate fire (natural or prescribed) in the landscape. Historically, frequent (approximately twice per decade), lightning-induced fires were a vital component in maintaining native vegetation and ecosystem functioning within south Florida pine rocklands (see Status Assessment, above). A period of just 10 years without fire may result in a marked decrease in the number of herbaceous species due to the effects of shading and litter accumulation (FNAI 2010, p. 63). Exclusion of fire for approximately 25 years will likely result in gradual hammock development over that time period, leaving a system that is very fire resistant if additional pre-fire management (

e.g.,

mechanical hardwood removal) is not undertaken.

Today, natural fires are unlikely to occur or are likely to be suppressed in the remaining, highly fragmented pine rockland habitat. The suppression of natural fires has reduced the size of the areas that burn, and habitat fragmentation has prevented fire from moving across the landscape in a natural way. Without fire, successional climax from pine rockland to rockland hammock takes 10 to 25 years, and displacement of native species by invasive nonnative plants often occurs. All occurrences of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

are affected by some degree of inadequate fire management, with the primary threat being shading by hardwoods (Bradley and Gann 1999, p. 15; Bradley and Gann 2005, page numbers not applicable). Shading may also be caused by a fire-suppressed (and, in some cases, planted) pine canopy that has evaded the natural thinning effects that fire has on seedlings and smaller trees. Gann (2013, pers. comm.) indicates this is also a threat to pine rockland habitat on the Miami Rock Ridge. Understory plants such as

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

are shaded out after just 10 years without fire, by hardwoods and nonnatives alike.

Whether the dense canopy is composed of pine, hardwoods, nonnatives, or a combination, seed germination and establishment are inhibited in fire-suppressed habitat due to accumulated leaf litter, which also changes soil moisture and nutrient availability (Hiers

et al.

2007, pp. 811-812). This alteration to microhabitat can also inhibit seedling establishment as well as negatively influence flower and fruit production (Wendelberger and Maschinski 2009, pp. 849-851), thereby reducing sexual reproduction in fire-adapted species such as

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

(Geiger 2002, pp. 78-79, 81-83).

After an extended period of inadequate fire management in pine rocklands, it becomes necessary to control invading native hardwoods mechanically, since excess growth of native hardwoods would result in a hot fire, which can cause mortality of pines and destroys the rootstocks and seed banks of other native plants. Mechanical treatments cannot entirely replace fire because pine trees, understory shrubs, grasses, and herbs all contribute to an ever-increasing layer of leaf litter, covering herbs and preventing germination, as discussed above. Leaf litter will continue to accumulate even if hardwoods are removed mechanically. In addition, the ashes left by fires provide important post-fire nutrient cycling, which is not provided via mechanical removal.

The impacts of fire on

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

are not entirely understood. Fire is critical in maintaining the open understory and species diversity in pine rocklands and marl prairies where these species occur, as well as to reduce populations of nonnative plant species. Fire maintains the ecotone (transition) between saw grass marsh, pine rockland, and rockland hammock habitats where

S. reclinatum

ssp.

austrofloridense

grows.

Some natural mortality of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

may occur from fire, especially more intense fires.

S. reclinatum

ssp.

austrofloridense

and

C. deltoidea

ssp.

pinetorum

grow in wet marl soils and soil deposits within cracks in the limestone bedrock, which provides protection to the roots and allows plants to resprout following fire.

C. deltoidea

ssp.

pinetorum,

in particular, possesses a well-developed rootstock that is protected from fire (ENP 2014, p. 203). Herndon (1998, p. 28) pointed out that the life history of

C. deltoidea

ssp.

pinetorum

includes a cryptic stage, making interpretation of mortality of aboveground parts difficult.

Currently, limited information is available on differences in mortality or long-term population impacts of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

resulting from wet or dry season burns. Indirect evidence suggests that burning in either season is suitable to maintain populations of

S. reclinatum

ssp.

austrofloridense, D. pauciflora,

and

C. deltoidea

ssp.

pinetorum

in pine rocklands. Prescribed fire in ENP was originally conducted during the dry season. Fire management was gradually shifted to wet-season burning in an effort to better mimic natural lightning-ignited fire patterns. As a result, pinelands and marl prairies in ENP where

S. reclinatum

ssp.

austrofloridense, D. pauciflora,

and

C. deltoidea

ssp.

pinetorum

occur have been burned in both the wet season and dry season. Long-term maintenance of populations in those areas indicates that either practice will sustain populations of these species.

Federal (Service, NPS), State (Florida Department of Environmental Protection (FDEP), Florida Fish and Wildlife Conservation Commission (FWC), and County (Miami-Dade DERM) land managers, and nonprofit organizations (Institute for Regional Conservation (IRC)) implement prescribed fire on public and private lands within the ranges of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana.

While management of some County conservation lands includes regular burning, other lands remain severely fire-suppressed. Even in areas under active management, some portions are typically fire-suppressed. Nevertheless, all of these sites retain a contingent of native species and a seedbank capable of responding to fire.

While ENP, BCNP, and various Miami-Dade County conservation lands (

e.g.,

Navy Wells Pineland Preserve) each attempt to administer prescribed burns, the threat of inadequate fire management still remains. The pine rocklands in the Long Pine Key region of ENP remained largely fire-suppressed for the past decade as the Park updated its fire management plan. Although prescribed fire was returned to Long Pine Key in early 2016, many areas retained substantial amounts of unburned understory vegetation. As a result, despite reintroduction of a fire regime, several large-scale wildfires ignited during the spring months of 2016, which burned up to 50 percent of the pine rocklands in Long Pine Key. Ultimately, this combination of prescribed burns and natural fires (if not too hot or lasting too long) is likely to improve conditions for

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

and

Chamaesyce deltoidea

ssp.

pinetorum

populations within ENP. For example, at 3 to 6 months post-burn, these species appear to be recolonizing burned areas (Sadle, pers. comm. 2016; Salvato, pers. obs. 2016). However, this chain of events also demonstrated the threat that prolonged or insufficient fire management may pose to local populations of an imperiled species, even on public conservation lands.

Implementation of a prescribed fire program in Miami-Dade County has been hampered by a shortage of resources, and by logistical difficulties and public concern related to burning next to residential areas. Many homes have been built in a mosaic of pine rockland, so the use of prescribed fire in many places has become complicated because of potential danger to structures and smoke generated from the burns. Nonprofit organizations such as IRC have similar difficulties in conducting prescribed burns due to difficulties with permitting and obtaining the necessary permissions as well as hazard insurance limitations (Gann 2013, pers. comm.). Few private landowners have the means and/or desire to implement prescribed fire on their property, and doing so in a fragmented urban environment is logistically difficult and may be costly. One of the few privately owned pine rocklands that is successfully managed with prescribed burning is Pine Ridge Sanctuary, located in a more agricultural (less urban) matrix of Miami-Dade, which was last burned in November 2010 (Glancy 2013, pers. comm.) and retains populations of both

Sideroxylon reclinatum

ssp.

austrofloridense

and

Chamaesyce deltoidea

ssp.

pinetorum.

Similarly, extant populations of

Dalea carthagenensis

var.

floridana

within the privately owned Charles Deering Estate and County-owned Crandon Park, are managed with fire.

Conservation Efforts To Reduce the Present or Threatened Destruction, Modification, or Curtailment of Habitat or Range

Miami-Dade County Environmentally Endangered Lands Covenant Program

In 1979, Miami-Dade County enacted the Environmentally Endangered Lands (EEL) Covenant Program, which reduces taxes for private landowners of natural forest communities (NFCs; pine rocklands and tropical hardwood hammocks) who agree not to develop their property and manage it for a period of 10 years, with the option to renew for additional 10-year periods (Service 1999, p. 3-177). Although these temporary conservation easements provide valuable protection for their duration, they are not considered under Factor D, below, because they are voluntary agreements and not regulatory in nature. Miami-Dade County currently has approximately 59 pine rockland properties enrolled in this program,

preserving 69.4 ha (172 ac) of pine rockland habitat (Johnson 2012, pers. comm.). The program also has approximately 21 rockland hammocks properties enrolled in this program, preserving 20.64 ha (51 ac) of rockland hammock habitat (Joyner 2013b, pers. comm.). The vast majority of these properties are small, and many are in need of habitat management such as prescribed fire and removal of nonnative invasive plants. Thus, while EEL covenant lands have the potential to provide valuable habitat for these plants and reduce threats in the near term, the actual effect of these conservation lands is largely determined by whether individual land owners follow prescribed EEL management plans and NFC regulations (see Local under Factor D).

Fee Title Properties

In 1990, Miami-Dade County voters approved a 2-year property tax to fund the acquisition, protection, and maintenance of natural areas by the EEL Program. The EEL Program purchases and manages natural lands for preservation. Land uses deemed incompatible with the protection of the natural resources are prohibited by current regulations; however, the County Commission ultimately controls what may happen with any County property, and land use changes may occur over time (Gil 2013, pers. comm.). To date, the Miami-Dade County EEL Program has acquired a total of approximately 313 ha (775 ac) of pine rockland, and 95 ha (236 ac) of rockland hammocks (Guerra 2015 pers. comm.; Gil 2013, pers. comm.). The EEL Program also manages approximately 314 ha (777 ac) of pine rocklands and 639 ha (1,578 ac) of rockland hammocks owned by the Miami-Dade County Parks, Recreation and Open Spaces Department, including some of the largest remaining areas of pine rockland habitat on the Miami Rock Ridge outside of ENP (

e.g.,

Larry and Penny Thompson Park, Zoo Miami pinelands, and Navy Wells Pineland Preserve), and some of the largest remaining areas of rockland hammocks (

e.g.,

Matheson Hammock Park, Castellow Hammock Park, and Deering Estate Park and Preserves).

Conservation efforts in Miami's EEL Preserves have been under way for many years. In Miami-Dade County, conservation lands are and have been monitored by FTBG and IRC, in coordination with the EEL Program, to assess habitat status and determine any changes that may pose a threat to or alter the abundance of these species. Impacts to habitat via nonnative species and natural stochastic events are monitored and actively managed in areas where the taxon is known to occur. These programs are long term and ongoing in Miami-Dade County; however, programs are limited by the availability of annual funding. In particular, fire management remains inadequate at many sites.

Since 2005, the Service has funded IRC to facilitate restoration and management of privately owned pine rockland habitats in Miami-Dade County. These programs included prescribed burns, nonnative plant control, light debris removal, hardwood management, reintroduction of pines where needed, and development of management plans. One of these programs, called the Pine Rockland Initiative, includes 10-year cooperative agreements between participating landowners and the Service/IRC to ensure restored areas will be managed appropriately during that time. Although most of these objectives have been achieved, IRC has not been able to conduct the desired prescribed burns, due to logistical difficulties as discussed above (see Fire Management).

Connect To Protect Program

FTBG, with the support of various Federal, State, local, and nonprofit organizations, has established the “Connect to Protect Network.” The objective of this program is to encourage widespread participation of citizens to create corridors of healthy pine rocklands by planting stepping stone gardens and rights-of-way with native pine rockland species, and restoring isolated pine rockland fragments. By doing this, FTBG hopes to increase the probability that pollination and seed dispersal vectors can find and transport seeds and pollen across developed areas that separate pine rockland fragments to improve gene flow between fragmented plant populations and increase the likelihood that these plants will persist over the long term. Although these projects may serve as valuable components toward the conservation of pine rockland species and habitat, they are dependent on continual funding, as well as participation from private landowners, both of which may vary through time.

National Park Service Lands

The NPS General Management Plans (GMPs) for ENP (NPS 2015) and BCNP (BCNP 2008) serve to protect, restore, and maintain natural and cultural resources at the ecosystem level. Although these GMPs are not regulatory, and their implementation is not mandatory, they do include conservation measures for

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

or

Dalea carthagenensis

var.

floridana.

Summary of Factor A

We have identified a number of threats to the habitat of the

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

that have operated in the past, are impacting these species now, and will continue to impact them in the future. Habitat loss, fragmentation, and degradation and associated pressures from increased human population are major threats; these threats are expected to continue, placing these plants at greater risk.

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

may be impacted when pine rocklands are converted to other uses or when lack of fire causes the conversion to hardwood hammocks or other unsuitable habitats.

On public lands, including Service, NPS, and Miami-Dade County-owned lands, implementation of prescribed fire has not been sufficient because of legal constraints (permitting requirements) and inadequate funding. Any populations of these four plants found on private property could be destroyed due to lack of protection. Although efforts are being made to conserve natural areas and apply prescribed fire, most pine rocklands remain in poor fire condition, and the long-term effects of large-scale and wide-ranging habitat modification, destruction, and curtailment will last into the future, while ongoing habitat loss due to population growth, development, and agricultural conversion continues to pose a threat to these species outside of conservation lands.

Therefore, based on the best information available, we have determined that the threats to

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

from habitat destruction, modification, or curtailment are occurring throughout the entire range of these species and are expected to continue into the future.

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

The best available data do not indicate that overutilization for commercial, recreational, scientific, or

educational purposes are a threat to

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

or

Dalea carthagenensis

var.

floridana.

Threats to these plants related to other aspects of recreation and similar human activities (

i.e.,

not related to overutilization) are discussed in Factor E.

Factor C. Disease or Predation

No diseases or incidences of predation have been reported for

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

or

Dalea carthagenensis

var.

floridana.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

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

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

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana.

Federal

Populations of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

within the Everglades and ENP and BCNP are protected by NPS regulations at 36 CFR 2.1, which prohibit visitors from harming or removing plants, listed or otherwise, from ENP or BCNP. However, the regulation does not address actions taken by NPS that cause mortality, or habitat loss or modification. NPS regulations do not require the application of prescribed fire or voluntary recovery actions for listed species.

In addition to occurring on ENP and BCNP,

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

may occur (we do not have recent surveys) on Federal lands within the Richmond Pine Rocklands, including lands owned by the U.S. Coast Guard and the National Oceanic and Atmospheric Association (NOAA; small portion of Martinez Pineland). There are no Federal protections for candidate species, including these four plants, on these properties. Otherwise, these plants occur primarily on State, County, or private land (Tables 1-4), and development of these areas will likely require no Federal permit or other authorization. Therefore, projects that affect them are usually not analyzed under the National Environmental Policy Act (NEPA) (42 U.S.C. 4321

et seq.

).

State

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

are listed on the Sate of Florida's Regulated Plant Index as endangered under Chapter 5B-40, Florida Administrative Code. This listing provides little or no habitat protection beyond the State's Development of Regional Impact process, which discloses impacts from projects, but provides no regulatory protection for State-listed plants on private lands.

Florida Statutes 581.185 sections (3)(a) and (b) prohibit any person from willfully destroying or harvesting any species listed as endangered or threatened on the Index, or growing such a plant on the private land of another, or on any public land, without first obtaining the written permission of the landowner and a permit from the Florida Department of Plant Industry. The statute further provides that any person willfully destroying or harvesting; transporting, carrying, or conveying on any public road or highway; or selling or offering for sale any plant listed in the Index as endangered must have a permit from the State at all times when engaged in any such activities.

However, subsections (8)(a) and (b) of the statute waive State regulation for certain classes of activities for all species on the Regulated Plant Index, including the clearing or removal of regulated plants for agricultural, forestry, mining, construction (residential, commercial, or infrastructure), and fire-control activities by a private landowner or his or her agent. On the other hand, section (10) of the statute provides for consultation similar to section 7 of the Federal Act for listed species by requiring the Department of Transportation to notify the FDACS and the Endangered Plant Advisory Council of planned highway construction at the time bids are first advertised, to facilitate evaluation of the project for listed plant populations, and to “provide for the appropriate disposal of such plants” (

i.e.,

transplanting).

Local

In 1984, Section 24-49 of the Code of Miami-Dade County established regulation of County-designated NFCs, which include both pine rocklands and tropical hardwood hammocks. These regulations were placed on specific properties throughout the county by an act of the Board of County Commissioners in an effort to protect environmentally sensitive forest lands. The Miami-Dade County Department of Regulatory and Economic Resources has regulatory authority over NFCs and is charged with enforcing regulations that provide partial protection on the Miami Rock Ridge. Miami-Dade Code typically allows up to 20 percent of a pine rockland designated as NFC to be developed, and requires that the remaining 80 percent be placed under a perpetual covenant. In certain circumstances, where the landowner can demonstrate that limiting development to 20 percent does not allow for “reasonable use” of the property, additional development may be approved. NFC landowners are also required to obtain an NFC permit for any work, including removal of nonnatives within the boundaries of the NFC on their property. The NFC program is responsible for ensuring that NFC permits are issued in accordance with the limitations and requirements of the code and that appropriate NFC preserves are established and maintained in conjunction with the issuance of an NFC permit. The NFC program currently regulates

approximately 600 pine rockland or pine rockland/hammock properties, comprising approximately 1,200 ha (3,000 ac) of habitat (Joyner 2013a, pers. comm.).

Although the NFC program is designed to protect rare and important upland (non-wetlands) habitats in south Florida, this regulatory strategy has limitations. For example, in certain circumstances where landowners can demonstrate that limiting development to 20 percent does not allow for “reasonable use” of the property, additional development may be approved. Furthermore, Miami-Dade County Code provides for up to 100 percent of the NFC to be developed on a parcel in limited circumstances for parcels less than 2.02 ha (5 ac) in size and requires coordination with the landowner only if the landowner plans to develop property or perform work within the NFC designated area. As such, the majority of the existing private forested NFC parcels consists of isolated fragments, without management obligations or preserve designation, as development has not been proposed at a level that would trigger the NFC regulatory requirements. Often, nonnative vegetation over time begins to dominate and degrade the undeveloped and unmanaged NFC landscape until it no longer meets the legal threshold of an NFC, which requires the land to be dominated by native vegetation. When development of such degraded NFCs is proposed, Miami-Dade County Code requires delisting of the degraded areas as part of the development process. Property previously designated as NFC is removed from the list even before development is initiated because of the abundance of nonnative species, making it no longer considered to be jurisdictional or subject to the NFC protection requirements of Miami-Dade County Code (Grossenbacher 2013, pers. comm.).

Summary of Factor D

Currently,

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

are found on Federal, State, and County lands; however, there is no regulatory mechanism in place that provides substantive protection of actual habitat or of potentially suitable habitat at this time. NPS regulations provide some protection at ENP and BCNP sites, whichprotect the largest and best managed populations. State regulations provide protection against trade, but allow private landowners or their agents to clear or remove species on the Florida Regulated Plant Index. State Park regulations provide protection for plants within Florida State Parks. The NFC program in Miami is designed to protect rare and important upland (non-wetlands) habitats in south Florida; however, this regulatory strategy has several limitations (as described above) that reduce its ability to protect

S. reclinatum

ssp.

austrofloridense, D. pauciflora,

C. deltoidea

ssp.

pinetorum,

and

D. carthagenensis

var.

floridana

and their habitats.

Although most populations of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

are afforded some level of protection because they are on public conservation lands, existing regulatory mechanisms have not led to a sufficient reduction of threats posed to these plants by a wide array of sources (see discussions under Factors A and E).

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

Other natural or manmade factors affect

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

to varying degrees, including the spread of nonnative invasive plants, potentially incompatible management practices (such as mowing and herbicide use), direct impacts to plants from recreation and other human activities, small population size and isolation, climate change, and the related risks from environmental stochasticity (extreme weather) on small populations. Each of these threats and its specific effect on these species are discussed in detail below.

Nonnative Plant Species

Nonnative invasive plants compete with native plants for space, light, water, and nutrients, and make habitat conditions unsuitable for

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana,

which prefer open conditions. Bradley and Gann (1999, pp. 13, 71-72) indicated that the control of nonnative plants is one of the most important conservation actions for the four plants and a critical part of habitat maintenance.

Nonnative plants have significantly affected pine rocklands, and negatively impact all occurrences of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

to some degree (Bradley 2006, pp. 25-26; Bradley and Gann 1999, pp. 18-19; Bradley and Saha 2009, p. 25; Bradley and van der Heiden 2013, pp. 12-16). As a result of human activities, at least 277 taxa of nonnative plants have invaded pine rocklands throughout south Florida (Service 1999, p. 3-175).

Schinus terebinthifolius

(Brazilian pepper) and

Neyraudia neyraudiana

(Burma reed) affect these species (Bradley and Gann 1999, pp. 13, 72). Brazilian pepper, a nonnative tree, is the most widespread and one of the most invasive species. It forms dense thickets of tangled, woody stems that completely shade out and displace native vegetation (Loflin 1991, p. 19; Langeland and Craddock Burks 1998, p. 54).

Lygodium microphyllum

(Old World climbing fern) is also a serious threat throughout south Florida.

Nonnative plants in pine rocklands can also affect the characteristics of a fire when it does occur. Historically, pine rocklands had an open, low understory where natural fires remained patchy with low temperature intensity.

S.

ssp.

austrofloridense, D. pauciflora,

C. deltoidea

ssp.

pinetorum,

and

D. carthagenensis

var.

floridana

thrive under this fire regime. However, dense infestations of

Neyraudia neyraudiana

and

Schinus terebinthifolius

cause higher fire temperatures and longer burning periods.

These nonnative species occur throughout the ranges of the four plants. In ENP and BCNP, invasives tend to be fewer due to the insularity of these sites and the NPS's control programs. Nevertheless, most areas require annual treatments to remove incipient invasions. Management of nonnative invasive plants in pine rocklands in Miami-Dade County is further complicated because the vast majority of pine rocklands are small, fragmented areas bordered by urban development. Areas near managed pine rockland that contain nonnative species can act as a seed source of nonnatives allowing them to continue to invade the surrounding pine rockland (Bradley and Gann 1999, p. 13).

Nonnative plant species are also a concern on private lands, where often they are not controlled due to associated costs, lack of interest, or lack of knowledge of detrimental impacts to the ecosystem. Undiscovered populations of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

on private lands could certainly be at risk. Overall, active management is necessary to control for nonnative

species and to protect unique and rare habitats where these plants occur (Snyder

et al.

1990, p. 273).

Mowing

While no studies have investigated the effect of mowing on

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

or

Dalea carthagenensis

var.

floridana,

research has been conducted on the federally endangered

Linum carteri

var.

carteri

(which also occurs in pine rocklands). The study found significantly higher densities of plants at the mown sites where competition with other plants is decreased (Maschinski

et al.

2007, p. 56). However, plants growing on mown sites were shorter, which may affect fruiting magnitude. While mowing did not usually kill adult plants, it could delay reproduction if it occurred prior to plants reaching reproductive status (Maschinski

et al.

2007, pp. 56-57). If such mowing occurs repeatedly, reproduction of those plants would be entirely eliminated. Maschinski

et al.

(2008, p. 28) recommended adjusting the timing of mowing to occur at least 3 weeks after flowering is observed to allow a higher probability of adults setting fruit prior to the mowing event. With flexibility and proper instructions to land managers and ground crews, mowing practices could be implemented in such a way as to scatter seeds and reduce competition with little effect on population reproductive output for the year (Maschinski

et al.

2008, p. 28). The exact impacts of mowing also depend on the timing of rainfall prior to and following mowing, and the numbers of plants in the population that have reached a reproductive state.

Recreation and Other Human Activities

Recreational use of off-road vehicles (ORV) is a threat to

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

and

Dalea carthagenensis

var.

floridana

occurrences within BCNP (K. Bradley

et al.

2013, p. 3). Operators frequently veer off established trails, and plants can be harmed or destroyed (Bradley and Gann 1999, p. 43). BCNP manages ORV access using a permit system, regulations, and designated trails. However, there are over 1,000 miles of ORV trails in BCNP, and only one enforcement officer (Pernas pers. comm., 2016), making enforcement of designated ORV trails a challenge. Current aerial imagery from the Lostman's Pine area of BCNP, where

Digitaria pauciflora

occurs, shows a criss-cross pattern of multiple ORV trails through the area. The Service is working with BCNP to determine the extent to which ORVs are affecting all three species at this site, particularly

D. pauciflora,

since it is one of only two sites where the species is known to exist. Damage from ORV use has also been documented for

Dalea carthagenensis

var.

floridana

within the Charles Deering Estate (J. Possley, pers. comm. 2008, 2009).

Dalea carthagenensis

var.

floridana

at the R. Hardy Matheson Preserve is also impacted by illegal mountain biking (Bradley and Gann 1999, pp. 43-45). In the past, this pineland fragment was heavily used by mountain bikers. In response Miami-Dade County has erected fencing to protect this site, which appears to have reduced this threat (Bradley and Gann 1999, p. 43).

Effects of Small Population Size and Isolation

Endemic species whose populations exhibit a high degree of isolation are extremely susceptible to extinction from both random and nonrandom catastrophic natural or human-caused events. Species that are restricted to geographically limited areas are inherently more vulnerable to extinction than widespread species because of the increased risk of genetic bottlenecks, random demographic fluctuations, effects of climate change, and localized catastrophes such as hurricanes and disease outbreaks (Mangel and Tier 1994, p. 607; Pimm

et al.

1988, p. 757). These problems are further magnified when populations are few and restricted to a very small geographic area, and when the number of individuals is very small. Populations with these characteristics face an increased likelihood of stochastic extinction due to changes in demography, the environment, genetics, or other factors (Gilpin and Soule 1986, pp. 24-34).

Small, isolated populations, such as those in fragmented habitat, often exhibit reduced levels of genetic variability, although the ultimate effect of these changes is dependent on a plant's specific life history, reproductive system, and interaction with pollinators and dispersal vectors (which may themselves be affected by fragmentation) (Young

et al.

1996, p. 413). While research results clearly indicate that isolation/fragmentation has population genetic consequences for plants, consequences are varied and for some species there may be a “fragmentation threshold” below which genetic variation is not lost (Young

et al.

1996, p. 416). No such studies have been conducted for

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana,

so whether these plants exhibit such a threshold is not known.

Reduced genetic variability generally diminishes a species' capacity to adapt and respond to environmental changes, thereby decreasing the probability of long-term persistence (

e.g.,

Barrett and Kohn 1991, p. 4; Newman and Pilson 1997, p. 361). Very small plant populations may experience reduced reproductive vigor due to ineffective pollination or inbreeding depression. Isolated individuals have difficulty achieving natural pollen exchange, which limits the production of viable seed. The problems associated with small population size and vulnerability to random demographic fluctuations or natural catastrophes are further magnified by synergistic (interaction of two or more components) effects with other threats, such as those discussed above (Factors A and C). Tables 1, 2, 3, and 4 above list the population sizes and the geographic ranges for

S. reclinatum

ssp.

austrofloridense, D. pauciflora,

C. deltoidea

ssp.

pinetorum,

and

D. carthagenensis

var.

floridana.

For example, table 2 lists

Digitaria pauciflora

as having 2 extant populations (ENP and BCNP), one estimated at 1,000-10,000 plants and the other with greater than 10,000 plants. The Service does not consider these as small populations; however, a large wildfire or severe flooding could be catastrophic. As shown in 2016,

D. pauciflora

was impacted by fire in ENP and flooding in ENP and BCNP, proving that the small geographic extent of the existing populations is not sufficient to eliminate the risk posed by large-scale disturbances.

Effects of Climate Change

Climatic changes, including sea level rise (SLR), are major threats to the flora of south Florida, including

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

or

Dalea carthagenensis

var.

floridana.

Our analyses under the Act include consideration of ongoing and projected changes in climate. With regard to our analysis for

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

or

Dalea carthagenensis

var.

floridana,

downscaled projections suggest that SLR is the largest climate-driven challenge to low-lying coastal areas in the subtropical ecoregion of southern Florida (U.S. Climate Change Science Program (USCCSP) 2008, pp. 5-31, 5-32).

The long-term record at Key West shows that sea level rose on average 0.229 cm (0.090 in) annually between 1913 and 2013 (NOAA 2013, p. 1). This equates to approximately 22.9 cm (9.02 in) over the last 100 years. IPCC (2008, p. 28) emphasized it is very likely that the average rate of SLR during the 21st century will exceed the historical rate. Heat trapped by greenhouse gases causes atmospheric warming, but the ocean is a vast heat sink where most of the increased heat energy is stored. As the water increases in temperature, its volume expands. Due to the thermal dynamic properties of water, as projected temperatures increase, so does the volume of the ocean, and the rate of expansion. As a result, most models show a dramatic increase in the rate of SLR rise by mid-century. The IPCC Special Report on Emission Scenarios (2000, entire) presented a range of scenarios based on the computed amount of change in the climate system due to various potential amounts of anthropogenic greenhouse gases and aerosols in 2100. Each scenario describes a future world with varying levels of atmospheric pollution leading to corresponding levels of global warming and corresponding levels of SLR. The IPCC Synthesis Report (2007, entire) provided an integrated view of climate change and presented updated projections of future climate change and related impacts under different scenarios.

Subsequent to the 2007 IPCC Report, the scientific community has continued to model SLR. Recent peer-reviewed publications indicate a movement toward increased acceleration of SLR. Observed SLR rates are already trending along the higher end of the 2007 IPCC estimates, and it is now widely held that SLR will exceed the levels projected by the IPCC (Rahmstorf

et al.

2012, p. 1; Grinsted

et al.

2010, p. 470). Taken together, these studies support the use of higher end estimates now prevalent in the scientific literature. Recent studies have estimated global mean SLR of 1-2 m (3.3-6.6 ft) by 2100 as follows: 0.75-1.90 m (2.5-6.2 ft; Vermeer and Rahmstorf 2009, p. 21530), 0.8-2.0 m (2.6-6.6 ft; Pfeffer

et al.

2008, p. 1342), 0.9-1.3 m (3.0-4.3 ft; Grinsted

et al.

2010, pp. 469-470), 0.6-1.6 m (2.0-5.2 ft; Jevrejeva

et al.

2010, p. 4), and 0.5-1.40 m (1.6-4.6 ft; National Resource Council 2012, p. 2).

Other processes expected to be affected by projected warming include temperatures, rainfall (amount, seasonal timing, and distribution), and storms (frequency and intensity) (discussed more specifically under Environmental Stochasticity, below). The Massachusetts Institute of Technology (MIT) modeled several scenarios combining various levels of SLR, temperature change, and precipitation differences with human population growth, policy assumptions, and conservation funding changes (see Alternative Future Landscape Models, below). All of the scenarios, from small climate change shifts to major changes, indicate significant effects on coastal Miami-Dade County.

Decades prior to inundation, pine rocklands are likely to undergo vegetation shifts related to climate change, triggered by changes to hydrology (wetter), salinity (higher) and increasing vulnerability to storm surge (pulse events causing massive erosion and salinization of soils) (Saha

et al.

2011, p. 82). Hydrology has a strong influence on plant distribution in these and other coastal areas (IPCC 2008, p. 57). Such communities typically grade from saltwater to brackish to freshwater species. From the 1930s to 1950s, increased salinity of coastal waters contributed to the decline of cabbage palm forests in southwest Florida (Williams

et al.

1999, pp. 2056-2059), expansion of mangroves into adjacent marshes in the Everglades (Ross

et al.

2000, pp. 101, 111), and loss of pine rockland in the Keys (Ross

et al.

1994, pp. 144, 151-155). In one Florida Keys pine rockland with an average elevation of 0.89 m (2.9 ft), Ross

et al.

(1994, pp. 149-152) observed an approximately 65 percent reduction in an area occupied by South Florida slash pine over a 70-year period, with pine mortality and subsequent increased proportions of halophytic (salt-loving) plants occurring earlier at the lower elevations. During this same time span, local sea level had risen by 15 cm (6.0 in), and Ross

et al.

(1994, p. 152) found evidence of groundwater and soil water salinization.

Extrapolating this situation to pine rocklands on the mainland is not straightforward, but indications are that similar changes to species composition could arise if current projections of SLR occur and freshwater inputs are not sufficient to prevent salinization. Furthermore, Ross

et al.

(2009, pp. 471-478) suggested that interactions between SLR and pulse disturbances (

e.g.,

storm surges) can cause vegetation to change sooner than projected based on sea level alone. Alexander (1953, pp. 133-138) attributed the demise of pinelands on northern Key Largo to salinization of the groundwater in response to SLR. Patterns of human development will also likely be significant factors influencing whether natural communities can move and persist (IPCC 2008, p. 57; USCCSP 2008, p. 7-6).

The Science and Technology Committee of the Miami-Dade County Climate Change Task Force (Wanless

et al.

2008, p. 1) recognized that significant SLR is a very real threat to the near future for Miami-Dade County. In a January 2008 statement, the committee warned that sea level is expected to rise at least 0.9-1.5 m (3-5 ft) within this century (Wanless

et al.

2008, p. 3). With a 0.9-1.2 m (3-4 ft) rise in sea level (above baseline) in Miami-Dade County, spring high tides would be at about 6 to 7 ft; freshwater resources would be gone; the Everglades would be inundated on the west side of Miami-Dade County; the barrier islands would be largely inundated; storm surges would be devastating; landfill sites would be exposed to erosion contaminating marine and coastal environments. Freshwater and coastal mangrove wetlands will not keep up with or offset SLR of 2 ft per century or greater. With a 5-ft rise (spring tides at nearly +8 ft), the land area of Miami-Dade County will be extremely diminished (Wanless

et al.

2008, pp. 3-4).

Drier conditions and increased variability in precipitation associated with climate change are expected to hamper successful regeneration of forests and cause shifts in vegetation types through time (Wear and Greis 2012, p. 39). Although this issue has not been well studied, existing pine rocklands have probably been affected by reductions in the mean water table. Climate changes are also forecasted to extend fire seasons and the frequency of large fire events throughout the Coastal Plain (Wear and Greis 2012, p. 43). These factors will likely cause an increase in wildfires and exacerbate complications related to prescribed burning (

i.e.,

less predictability related to rainfall, fuel moisture, and winds) or other management needed to restore and maintain habitat for the four plants. While restoring fire to pine rocklands is essential to the long-term viability of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

populations, increases in the scale, frequency, or severity of wildfires could have negative effects on these plants considering their general vulnerability due to small population size, restricted range, few occurrences, and relative isolation. Big, hot wildfires can destroy essential habitat features of pine rockland habitat. In addition, hot burns with long residence times (which are more likely under wildfire conditions)

can also sterilize the soil seed bank and cause a demographic crash in plant populations.

Alternative Future Landscape Models

To accommodate the large uncertainty in SLR projections, researchers must estimate effects from a range of scenarios. Various model scenarios developed at MIT and GeoAdaptive Inc. have projected possible trajectories of future transformation of the south Florida landscape by 2060 based upon four main drivers: climate change, shifts in planning approaches and regulations, human population change, and variations in financial resources for conservation. The scenarios do not account for temperature, precipitation, or species habitat shifts due to climate change, and no storm surge effects are considered. The current MIT scenarios range from an SLR of 0.09-1.0 m (0.3-3.3 ft) by 2060 (Vargas-Moreno and Flaxman 2010, pp. 1-6).

Based on the most recent estimates of anticipated SLR, the upward trend in recent projections toward the higher range of earlier SLR estimates (discussed above), and the data available to us at this time, we evaluated potential effects of SLR using the current “high” range MIT scenario as well as comparing elevations of remaining pine rockland fragments and extant and historical occurrences of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana.

The “high” range (or “worst case”) MIT scenario assumes high SLR (1 m (3.3 ft) by 2060), low financial resources, a “business as usual” approach to planning, and a doubling of human population.

The rate of SLR will increase as time passes. This is due to atmospheric and ocean warming and the thermal expansion properties of water. In SLR models the rate of sea level rise is projected to increase dramatically around mid-century.

Most populations of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

and

Chamaesyce deltoidea

ssp.

pinetorum

occur at elevations less than 2 m (6.6 ft) above sea level, making these species highly susceptible to increased storm surges and related impacts associated with SLR. Areas of the Miami Rock Ridge in Miami-Dade County (located to the east of ENP and BCNP) are higher elevation (maximum of 7 m [22 ft] above sea level) than those in BCNP (FNAI 2010, p. 62). However, plant communities along South Florida's low-lying coasts are organized along a mild gradient in elevation, transitioning from mangroves at sea level to salinity-intolerant interior habitats, including pine rocklands and hardwood hammocks within an elevation change of 2 m (6.5 ft) above sea level. As a result, a rise of 1 m (3.3 ft) in sea level is expected to render coastal systems susceptible to increased erosion and cause these areas to transition from upland forest habitats to saline wetland habitats.

Prior to the onset of sustained inundation, there will be irreversible changes in vegetation composition within these habitats. Shifts in habitat toward hydric and saline ecosystems may occur decades in advance of full inundation, rendering the habitat unsuitable for salt-intolerant species including

S. reclinatum

ssp.

austrofloridense, D. pauciflora,

C. deltoidea

ssp.

pinetorum,

and

D. carthagenensis

var.

floridana

(Saha

et al.

2011, p. 82). As interior habitats become more saline there will be a reduction in freshwater inflows to the estuarine portions of ENP and BCNP, accelerating losses in salinity-intolerant coastal plant communities (Saha

et al.

2011, p. 105), such as

S. reclinatum

ssp.

austrofloridense, D. pauciflora,

C. deltoidea

ssp.

pinetorum,

or

D. carthagenensis

var.

floridana.

Actual impacts may be greater or less than anticipated based upon the high variability of factors involved (

e.g.,

SLR, human population growth) and assumptions made, but based on the current “high” range MIT scenario, pine rocklands, marl prairies and associated habitats along the coast in central and southern Miami-Dade County would become inundated. The “new” sea level would occur at the southern end of the Miami Rock Ridge (the eastern edge of the Everglades). However, in decades prior to the fully anticipated sea level rise, changes in the water table and increased soil salinity from partial inundation and storm surge will result in vegetation shifts within BCNP, ENP, and conservation lands on the southern Miami Rock Ridge. Inundation will result in pine rocklands gaining increased marl prairie characteristics. Marl prairies, in turn, will transition to sawgrass or more hydric conditions, due to increased inundation.

As a result, species such as

Digitaria pauciflora

and

Sideroxylon reclinatum

ssp.

austrofloridense,

which are most abundant within the ecotone between pine rocklands and marl prairies, will gradually decline as these habitat types merge and eventually disappear. Under this scenario, by 2060, all extant populations of

Digitaria pauciflora,

as well as the largest populations of

Sideroxylon reclinatum

ssp.

austrofloridense

and

Dalea carthagenensis

var.

floridana,

would likely be lost or significantly impacted by shifts in vegetation communities. Populations of

Sideroxylon reclinatum

ssp.

austrofloridense, Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

would likely remain only at the highest elevations along the Miami Rock Ridge. In addition, many existing pine rockland fragments are projected to be developed for housing as the human population grows and adjusts to changing sea levels under this scenario.

Further or Additional Impacts Expected Beyond 2060

Further direct losses to extant populations of all four plants are expected due to habitat loss and modification from SLR through 2100. We analyzed existing sites that support populations of the four plants using the National Oceanic and Atmospheric Administration (NOAA) Sea Level Rise and Coastal Impacts viewer. Below we discuss general implications of sea level rise within the range of projections discussed above on the current distribution of these species. The NOAA tool uses 1-foot increments. Our analysis is based on 0.91 m (3 ft) and 1.8 m (6 ft) of SLR.

Based on a higher SLR of 1.8 m (6 ft), as projected by NOAA, much larger portions of urban Miami-Dade County, including conservation areas, such as Navy Wells Pineland Preserve, will be inundated by 2100. Under such a 1.8-meter SLR projection, both extant populations of

D. pauciflora

in ENP and BCNP would be almost entirely inundated by 2100, and the species will be extinct. Several extant occurrences of

Sideroxylon reclinatum

ssp.

austrofloridense, Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

would also be lost. The western part of urban Miami-Dade County would also be inundated (barring creation of sea walls or other barriers), creating a virtual island of the Miami Rock Ridge.

Following a 1.8-m (6-ft) rise in sea level, approximately 75 percent of presently extant pine rocklands on the Miami Rock Ridge would still remain above sea level. However, an unknown percentage of remaining pine rockland fragments would be negatively impacted by water table and soil salinization, which would be further exacerbated due to isolation from mainland fresh water flows.

Projections of SLR above 1.8 m (6 ft) indicate that very little pine rockland would remain, with the vast majority either being inundated or experiencing

vegetation shifts, resulting in the extirpation of all known populations of

Digitaria pauciflora, Sideroxylon reclinatum

ssp.

austrofloridense, Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana.

Environmental Stochasticity

Endemic species whose populations exhibit a high degree of isolation and narrow geographic distribution, such as

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana,

are extremely susceptible to extinction from both random and nonrandom catastrophic natural or human-caused events. Small populations of species, without positive growth rates, are considered to have a high extinction risk from site-specific demographic and environmental stochasticity (Lande 1993, pp. 911-927).

The climate of southern Florida is driven by a combination of local, regional, and global events, regimes, and oscillations. There are three main “seasons”: (1) the wet season, which is hot, rainy, and humid from June through October; (2) the official hurricane season that extends one month beyond the wet season (June 1 through November 30), with peak season being August and September; and (3) the dry season, which is drier and cooler, from November through May. In the dry season, periodic surges of cool and dry continental air masses influence the weather with short-duration rain events followed by long periods of dry weather.

Florida is considered the most vulnerable State in the United States to hurricanes and tropical storms (Florida Climate Center,

http://coaps.fsu.edu/climate_center

). Based on data gathered from 1856 to 2008, Klotzbach and Gray (2009, p. 28) calculated the climatological probabilities for each State being impacted by a hurricane or major hurricane in all years over the 152-year timespan. Of the coastal States analyzed, Florida had the highest climatological probabilities, with a 51 percent probability of a hurricane (Category 1 or 2) and a 21 percent probability of a major hurricane (Category 3 or higher). From 1856 to 2015, Florida actually experienced 109 hurricanes and 36 major hurricanes. While not every hurricane will pass over south Florida, given the low population sizes and restricted ranges of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana

within locations prone to storm influences, these species are at substantial risk from hurricanes, storm surges, and other extreme weather. Depending on the location and intensity of a hurricane or other severe weather event, it is possible that the plants could become extirpated or extinct.

Hurricanes, storm surge, and extreme high tide events are natural events that can negatively impact these four plants. Hurricanes and tropical storms can modify habitat (

e.g.,

through storm surge) and have the potential to destroy entire populations, physically washing them away or leaving soil too saline for them to persist. Climate change may lead to increased frequency and duration of severe storms (Golladay

et al.

2004, p. 504; McLaughlin

et al.

2002, p. 6074; Cook

et al.

2004, p. 1015).

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

or

Dalea carthagenensis

var.

floridana

experienced these disturbances historically, but had the benefit of more abundant and contiguous habitat to buffer them from extirpations. With most of the historical habitat having been destroyed or modified, the few remaining populations of these species could face local extirpations due to stochastic events.

Other processes to be affected by climate change, related to environmental stochasticity, include temperatures, rainfall (amount, seasonal timing, and distribution), and storms (frequency and intensity). Temperatures are projected to rise from 2-5 °C (3.6-9 °F) for North America by the end of this century (IPCC 2007, pp. 7-9, 13). These factors will likely cause an increase in wildfires and exacerbate complications related to prescribed burning or other management needed to restore and maintain habitat for the four plants. Based upon modeling, Atlantic hurricane and tropical storm frequencies are expected to decrease (Knutson

et al.

2008, pp. 1-21). By 2100, there should be a 10-30 percent decrease in hurricane frequency. Hurricane frequency is expected to drop due to more wind shear impeding initial hurricane development. However, hurricane winds are expected to increase by 5-10 percent, which will increase storm surge heights. This is due to more hurricane energy being available for intense hurricanes. In addition to climate change, weather variables are extremely influenced by other natural cycles, such as El Niño Southern Oscillation with a frequency of every 4-7 years, solar cycle (every 11 years), and the Atlantic Multi-decadal Oscillation. All of these cycles influence changes in Floridian weather. The exact magnitude, direction, and distribution of all of these changes at the regional level are difficult to project.

Freezing Temperatures

Occasional freezing temperatures that occur in south Florida pose a risk to

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

or

Dalea carthagenensis

var.

floridana,

causing damage or death to individual plants. Under normal circumstances, occasional freezing temperatures would not result in a significant impact to populations of these plants; however, the small size of some populations means the loss from freezing events of even a few individuals can reduce the viability of the population.

Hydrology and Everglades Restoration

Hydrology is a key ecosystem component that affects rare plant distributions and their viability (Gann

et al.

2006, p. 4). Historically, sheet flow from Shark River Slough and Taylor Slough did not reach the upland portions of Long Pine Key, but during the wet season increased surface water flow in sloughs generated a rise in ground water across the region (Gann

et al.

2006, p. 4). Water flow through Long Pine Key was originally concentrated in marl prairies, traversing in a north-south direction; however, construction of the main ENP road dissected Long Pine Key in an east-west direction, thereby impeding sheet flow across this area (Gann

et al.

2006, p. 4). Water was either impounded to the north of the main ENP road or diverted around the southern portion of Long Pine Key through Taylor Slough and Shark River Slough (Gann

et al.

2006, p. 4). As artificial drainage became more widespread, however, regional groundwater supplies declined.

While projects designed to restore the historical hydrology of the Everglades and other natural systems in southern Florida, including ENP and BCNP (collectively known as the Comprehensive Everglades Restoration Plan (CERP)), are beneficial to the Everglades ecosystem, some may produce collateral impacts to extant pine rockland, marl prairies, and associated habitats within the region through inundation or increased hydroperiods. The effects of changes in regional hydrology through restoration may have impacts on the four plant species and their habitats. Sadle (2012, pers. comm.) suggested various CERP projects (such as C-111 spreader canal; L-31N seepage barrier), specifically the operation of pumps and associated detention areas along the ENP

boundary, may influence (through excessive water discharges) select portions of eastern Long Pine Key. Increased and longer-duration hydroperiods within the pine rockland and marl prairie habitats where these species occur may lead to a reduction in the amount of suitable habitat, a potential reduction in the area occupied and a reduction in the number of individuals found in ENP and BCNP. It is unclear to what extent this may occur, if at all. In an effort to establish a baseline assessment of future hydrologic modifications, long-term monitoring transects and plots for

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

and

Chamaesyce deltoidea

ssp.

pinetorum

were established in Long Pine Key between 2003 and 2008 (Gann 2015, p. 169).

Conservation Efforts To Reduce Other Natural or Manmade Factors Affecting Continued Existence

NPS, the Service, Miami-Dade County, and the State of Florida have ongoing nonnative plant management programs to reduce threats on public lands, as funding and resources allow. In Miami-Dade County, nonnative, invasive plant management is very active, with a goal to treat all publicly owned properties at least once a year and more often in many cases. IRC and FTBG conduct research and monitoring in various natural areas within Miami-Dade County and the Florida Keys for various endangered plant species and nonnative, invasive species. For the four plants, monitoring detects declines that lead to small population size, changes in habitat due to SLR, and declines due to stochastic events. For nonnatives, monitoring is an integral part of efforts to detect and control invasive plant and animal species.

Summary of Factor E

We have discussed threats from other natural or manmade factors including: nonnative invasive plants, management practices (such as mowing and herbicide use), recreation (including ORV use), effects from small population size and isolation, limited geographic range, and stochastic events including hurricanes, storm surges, and wildfires. Additionally, these plants are particularly vulnerable to the effects of climate change, including SLR, as changes in the water table, increased soil salinity from partial inundation, and storm surge will likely result in vegetation shifts in the decades prior to the fully anticipated sea level rise. Some of these threats (

e.g.,

nonnative species) may be reduced on public lands due to active programs by Federal, State, and County land managers. Many of the remaining populations of these plants are small and geographically isolated, and genetic variability is likely low, increasing the inherent risk due to overall low resilience of these plants. The threats act together to impact populations of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

or

Dalea carthagenensis

var.

floridana.

Cumulative Effects of Threats

When two or more threats affect populations of

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana,

the effects of those threats could interact or become compounded, producing a cumulative adverse effect that is greater than the impact of either threat alone. The most obvious cases in which cumulative adverse effects would be significant are those in which small populations (Factor E) are affected by threats that result in destruction or modification of habitat (Factor A), ORV damage (Factor E), or stochastic events, such as hurricanes, storm surges, wildfires (Factor E). The limited distributions and/or small population sizes of many populations of

S. reclinatum

ssp.

austrofloridense, D. pauciflora,

C. deltoidea

ssp.

pinetorum,

and

D. carthagenensis

var.

floridana

make them extremely susceptible to the detrimental effects of further habitat modification, degradation, and loss, as well as other anthropogenic threats. Mechanisms leading to the decline of

S. reclinatum

ssp.

austrofloridense, D. pauciflora,

C. deltoidea

ssp.

pinetorum,

and

D. carthagenensis

var.

floridana,

as discussed above, range from local (

e.g.,

agriculture) to regional (

e.g.,

development, fragmentation, nonnative species) to global influences (

e.g.,

effects of climate change, SLR). The synergistic effects of threats, such as impacts from hurricanes on a species with a limited distribution and small populations, make it difficult to predict population viability. While these stressors may act in isolation, it is more probable that many stressors are acting simultaneously (or in combination) on populations of

S. reclinatum

ssp.

austrofloridense, D. pauciflora,

C. deltoidea

ssp.

pinetorum,

and

D. carthagenensis

var.

floridana,

making them more vulnerable.

Proposed Determination

We have carefully assessed the best scientific and commercial data available regarding the past, present, and future threats to

Sideroxylon reclinatum

ssp.

austrofloridense, Digitaria pauciflora,

Chamaesyce deltoidea

ssp.

pinetorum,

and

Dalea carthagenensis

var.

floridana.

Sideroxylon reclinatum

ssp.

austrofloridense

Nine of 11 extant populations are located on publicly owned conservation lands. This includes 10,000-100,000 plants at ENP, and a small population at BCNP, where prescribed fire implementation has improved, and nonnative plant control efforts are adequate to beneficially manage habitat for native species. In contrast, in the scattered small populations on Miami-Dade habitat fragments, representing half of the species' historical range, habitat management currently is not adequate due to the inability to conduct prescribed fire. Increasing temperatures and changes in precipitation patterns associated with climate change will likely cause an increase in wildfires and exacerbate complications related to prescribed burning or other management needed to restore and maintain habitat for the species. In the current, fragmented landscape, dispersal and genetic exchange for any of these smaller Miami-Dade populations is unlikely, because they exist in isolated habitat patches surrounded by miles of unsuitable habitat (agriculture and urban development). Two privately owned sites in Miami supporting extant populations are vulnerable to development. The largest populations (ENP and BCNP) are vulnerable to hydrologic changes related to Everglades restoration projects and SLR.

SLR projections suggest future inundation and modification to the majority of

Sideroxylon reclinatum

ssp.

austrofloridense

habitat in ENP and BCNP by 2060. Decades prior to inundation, however, pine rocklands, marl prairies, and associated habitats within ENP and BCNP will undergo habitat transitions toward wetter, salt-tolerant plant communities, hydrological changes, and increasing vulnerability to storm surge. Although the effects of SLR within urban Miami-Dade fragments may be less severe, these pine rocklands will, at a minimum, experience partial inundations and vegetation shifts. In addition, many existing Miami-Dade pine rockland fragments are projected to be developed for housing as the human population grows and adjusts to changing sea levels under this scenario.

Digitaria pauciflora

Only two of five historical

Digitaria pauciflora

locations are extant. They are located in BCNP (>10,000 plants) and

ENP (1,000-10,000 plants) on publicly owned conservation lands where habitat management (prescribed fire and nonnative plant control) is ongoing and includes addressing a backlog of long-unburned sites that could result in larger wildfires if burns are not implemented. In addition, although we do not have evidence of direct impacts, given the mapped overlap of ORV trails with

Digitaria pauciflora

locations, ORV use in BCNP has likely resulted in damage to

Digitaria pauciflora

plants and habitat. The scattered small populations that once occurred in Miami-Dade habitat fragments, representing the remainder of the species' historical range, are extirpated, and current habitat management does not allow for prescribed fire to be conducted on a consistent basis. Increasing temperatures and changes in precipitation patterns associated with climate change will likely cause an increase in wildfires and exacerbate complications related to prescribed burning or other management needed to restore and maintain habitat for the species.

Digitaria pauciflora

previously occurred within the Richmond Pine Rocklands, an area that retains the largest remaining contiguous privately and publicly owned pine rocklands in Miami-Dade County, outside of ENP. In terms of restoring the species' historical range, the Richmond Pine Rocklands would serve as one of the most important sites in Miami-Dade County for recovery efforts (

i.e.,

reintroduction). The largest populations (ENP and BCNP) are vulnerable to hydrological changes related to Everglades restoration projects and SLR.

SLR projections suggest future partial inundation and modification to the majority of

D. pauciflora

habitat by 2060. Decades prior to inundation, however, pine rocklands, marl prairies, and associated habitats within ENP and BCNP will undergo habitat transitions toward wetter, salt-tolerant plant communities, hydrological changes, and increase in vulnerability to storm surge. Although the effects of SLR within urban Miami-Dade fragments may be less severe, these pine rocklands will, at a minimum, experience partial inundations and vegetation shifts. In addition, many existing Miami-Dade pine rockland fragments are projected to be developed for housing as the human population grows and adjusts to changing sea levels under this scenario.

Chamaesyce deltoidea ssp. pinetorum

Eleven of 20 extant populations are located on publicly owned conservation lands. This includes 10,000-100,000 plants at ENP and 1,000 plants at Navy Wells pineland, where habitat management (prescribed fire and nonnative plant control) is ongoing, and includes addressing a backlog of long-unburned sites that could result in larger wildfires if burns are not implemented. In contrast, in the scattered small populations on Miami-Dade habitat fragments, representing half of the species' historical range, current habitat management does not allow for prescribed fire to be conducted on a consistent basis. Increasing temperatures and changes in precipitation patterns associated with climate change will likely cause an increase in wildfires and exacerbate complications related to prescribed burning or other management needed to restore and maintain habitat for the species. In the current, fragmented landscape, dispersal and genetic exchange for any of these smaller Miami-Dade populations is unlikely, because they exist in isolated habitat patches surrounded by miles of unsuitable habitat (agriculture and urban development). Eight privately owned sites in Miami suppo

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