# Endangered and Threatened Wildlife and Plants; Endangered Species Status for Trichomanes punctatum ssp. floridanum (Florida Bristle Fern)

> Briefs, arguments, decisions, and more.

URL: https://www.frixlaw.com/law-library/documents/fr%3A2015-25299

## Record

- **Collection:** Federal Register
- **Document type:** Rule
- **Published:** October 6, 2015
- **Citation:** 80 FR 60440

## Text

DEPARTMENT OF THE INTERIOR
Fish and Wildlife Service
50 CFR Part 17
[Docket No. FWS-R4-ES-2014-0044; 4500030113]
RIN 1018-AY97

Endangered and Threatened Wildlife and Plants; Endangered Species Status for
Trichomanes punctatum ssp. floridanum
(Florida Bristle Fern)

AGENCY:

Fish and Wildlife Service, Interior.

ACTION:

Final rule.

SUMMARY:

We, the U.S. Fish and Wildlife Service (Service), determine endangered species status under the Endangered Species Act of 1973 (Act), as amended, for
Trichomanes punctatum
ssp.
floridanum
(Florida bristle fern), a plant subspecies from Miami-Dade and Sumter Counties, Florida. The effect of this regulation will be to add this subspecies to the Federal List of Endangered and Threatened Plants and extend the Act's protections to this subspecies.

DATES:

This rule becomes effective on November 5, 2015.

ADDRESSES:

This final rule is available on the internet at
http://www.regulations.gov
and
http://www.fws.gov/verobeach/
. Comments and materials we received, as well as supporting documentation we used in preparing this rule, are available for public inspection at
http://www.regulations.gov
. All of the comments, materials, and documentation that we considered in this rulemaking are available by appointment, during normal business hours at: U.S. Fish and Wildlife Service, South Florida Ecological Services Office, 1339 20th Street, Vero Beach, FL 32960; telephone 772-562-3909.

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, a species may warrant protection through listing if it is endangered or threatened throughout all or a significant portion of its range. Listing a species as an endangered or threatened species can only be completed by issuing a rule. This rule will finalize the listing of the
Trichomanes punctatum
ssp.
floridanum
(Florida bristle fern) as an endangered species.

The basis for our action.
Under the Act, we can determine that a species is an endangered or threatened species based on any of five factors: (A) The present or threatened destruction, modification, or curtailment of its habitat or range; (B) Overutilization for commercial, recreational, scientific, or educational purposes; (C) Disease or predation; (D) The inadequacy of existing regulatory mechanisms; or (E) Other natural or manmade factors affecting its continued existence. We have determined that the threats to
Trichomanes punctatum
ssp.
floridanum
consist primarily of destruction and modification of habitat (Factor A), proliferation of nonnative invasive species, natural stochastic events including hurricanes and tropical storms, and impacts from climate change including temperature shifts and sea level rise (Factor E), and that existing regulatory mechanisms have not reduced or removed such threats (Factor D).

Peer review and public comment.
We sought comments from independent specialists to ensure that our designation is based on scientifically sound data, assumptions, and analyses. We invited these peer reviewers to comment on our listing proposal. We also considered all comments and information received during the comment period.

Previous Federal Actions

Please refer to the proposed listing rule for
Trichomanes punctatum
ssp.
floridanum
(79 FR 61136), published on October 9, 2014, for a detailed description of previous Federal actions concerning this subspecies.

Our proposed listing rule included a finding that designation of critical habitat was prudent, but that critical habitat was not determinable. In this final listing rule, we find that critical habitat is still not determinable (see Critical Habitat discussion below).

Background

Below we present updated and revised information, based on peer review and public comment received during the comment period on the proposed rule, as well as new information, related to the subspecies' life history, historical and current ranges, and habitat requirements.

Species Description

Trichomanes punctatum
ssp.
floridanum,
commonly referred to as the Florida bristle fern, is mat-forming, has root-like structures, and contains trichomes (hairlike/bristlelike outgrowths), which extend from soral involucres (tubes containing sporangia (an enclosure in which spores, or reproductive cells, are formed)) on the tips of some fronds (leaves of ferns) when the plant is fertile (Wunderlin and Hansen 2000, pp. 153-154). This subspecies is very small in size and superficially resembles bryophytes, such as mosses and liverworts, making it difficult to observe in its natural habitat.

Wunderlin and Hansen (2000, pp. 153-154) described
Trichomanes punctatum
ssp.
floridanum
as having leaves, with the petiole (stalk by which a leaf is attached to a plant) 0.1-2.0 centimeters (cm) (0.04-0.79 inches (in)) long and typically shorter than the blade. The blade is fan-shaped, round, entire or irregularly lobed at the apex, and 0.5-2.0 cm (0.20-0.79 in) long and 0.2-1.1 cm (0.08-0.43 in) wide.
T. p.
ssp.
floridanum
has thin veinlets (small veins) that are not enlarged towards the margin while true veins are uniform in width to their apices (tips) (Nauman 1986, p. 179). This subspecies has few false veins, and fronds are considered simple (Morton 1963, p. 89).

One unusual characteristic of this plant is that it lacks cuticles (the protective layer that covers the epidermis, which is the outermost layer of cells that cover the leaves) or has highly reduced cuticles. The fern has differentiated epidermises and stomata (small openings in leaves and stems through which gases are exchanged), causing it to be dependent on elevated moisture conditions because a barrier is not present to prevent unregulated loss of water (Krömer and Kessler 2006, p. 57). This dependence restricts most
Trichomanes
ssp. to shaded areas within forested environments with high humidity, making them more vulnerable to changes in localized climatic conditions (Schuster 1971, p. 91; Nauman 1986, pp. 181-182; van der Heiden 2014, p. 5).

Taxonomy

The genus
Trichomanes
contains approximately 320 species of ferns that occur primarily in the tropics and for which we generally lack ecological information (Nauman 1986, p. 179; Nelson 2000, p. 77). The genus belongs to the family Hymenophyllaceae and the hymenophylloid clade, where ferns are also referred to as filmy ferns, which

describes the thin, filmy leaves of the species (Nelson 2000, p. 77). The common name, bristle fern, is used to reference the bristlelike structure that singularly protrudes from each soral involucre (a structure that holds and produces spores) (Nelson 2000, p. 77).

Five species commonly known as bristle ferns (
Trichomanes
ssp.) have been found in Florida (Krömer and Kessler 2006, p. 57).
Trichomanes punctatum
ssp.
floridanum
is a subspecies of
Trichomanes punctatum,
the current taxonomy of which is the result of monographic revision of
Trichomanes
sections (a taxonomic rank or position below the genus but above the species)
Didymoglossum
and
Microgonium
by Wessels Boer (1962, pp. 300-301). All U.S. species of
Trichomanes
now belong to the section
Didymoglossum,
except
T. boschianum
(Morton 1963). Wessels Boer, in reviewing specimens from throughout the American tropics, determined that all
Trichomanes punctatum
plants in Florida represented the same taxon, not two separate species, and that
T. sphenoides
(which he described as
T. punctatum
ssp.
sphenoides
) does not occur in Florida. He further determined that
Trichomanes punctatum
plants in Florida were different from those in the tropics and described them as a new subspecies,
Trichomanes punctatum
ssp.
floridanum
(Boer 1962, pp. 300-301). This treatment has been followed by almost all subsequent authors (Lakela and Long 1976, p. 53; Wunderlin 1982, p. 32; Lellinger 1985, p. 205; Nauman 1986, p. 181; Flora of North America Editorial Committee 1993, p. 196; Wunderlin 1998, p. 44; Nelson 2000, p. 81; Wunderlin and Hansen 2000, p. 153; Wunderlin and Hansen 2003, p. 44). The only exception is Long and Lakela (1971, p. 73), who treated the subspecies as
T. punctatum
without further explanation. Additionally, the following entities use the name
T. p.
ssp.
floridanum
and indicate that this subspecies' taxonomic standing is accepted:

• Florida Department of Agriculture and Consumer Services (2013,
https://www.flrules.org/gateway/RuleNo.asp?title=PRESERVATION%20OF%20NATIVE%20FLORA%20OF%20FLORIDA&ID=5B-40.0055
),

• The Integrated Taxonomic Information System (2011, p. 1),

• NatureServe (2013,
http://explorer.natureserve.org/servlet/NatureServe?loadTemplate=tabular_report.wmt&paging=home&save=all&sourceTemplate=reviewMiddle.wmt
),

• The online Atlas of Florida Vascular Plants (Wunderlin and Hansen 2008, (
http://www.florida.plantatlas.usf.edu/Plant.aspx?id=1122
),

• The Flora of North America (
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=233501316
), and

• The Florida Natural Areas Inventory (FNAI) (FNAI, 2013,
http://fnai.org/trackinglist.cfm
).

In summary, there is consensus that
Trichomanes punctatum
ssp.
floridanum
is a distinct taxon.

Currently there are two extant metapopulations (groups of spatially separated populations) of this subspecies (Gann
et al.
2002, pp. 552-554), comprising four populations in Miami-Dade County and two in Sumter County, separated by a distance of approximately 400 kilometers (km) (249 miles (mi)). As noted by Small (1938, p. 50), the Sumter metapopulation is a considerable distance from where
T. p.
ssp.
floridanum
was first discovered (
i.e.,
south Florida) and resides in a climate and habitat unlike the Miami-Dade County metapopulation. These differences are likely why Morton (1963, p. 90) suggested that the previous determination of these two metapopulations be reviewed. In March 2014, the Service contracted researchers from Florida Atlantic University to determine if the two metapopulations were the same subspecies. Samples were collected from both metapopulations for genetic analysis. DNA was isolated from the samples, and sequencing was completed on five samples from each metapopulation. Researchers found no observable differences in the sequence between the five samples collected from Miami-Dade County and the five samples from Sumter County, indicating that both metapopulations are the same subspecies (Hughes 2014, pp. 1-4).

Life History

The life cycle of ferns is not commonly understood (Possley 2014c, pers. comm.). Information about the specific life cycle of
T. p.
ssp.
floridanum
is also lacking. Like all ferns, this taxon has two life-history stages, a gametophyte stage and a sporophyte stage, and only the sporophyte form is recognizable in the wild, while the gametophyte form is very cryptic (Possley 2013a, pers. comm.; van der Heiden 2013b, pers. comm.). Therefore, all reported populations of
Trichomanes punctatum
ssp.
floridanum
have been in the sporophyte stage.

Mature plants can reproduce sexually or asexually. The initial stage, when a spore germinates, is referred to as the gametophyte stage. The gametophyte contains separate sperm and egg-producing structures. In the presence of water or moisture, sperm reach the eggs for fertilization. Fertilized eggs, under the proper conditions, develop into sporophytes. The sporophytes produce spores, which in turn can germinate to produce new gametophytes (Nelson 2000, pp. 17-19). Reproduction may also occur in one other way: By division, when rhizomes (horizontal, underground plant stems capable of producing the shoot and root-like structures of a new plant) break, forming clones of the parent plant.

Although it has been suggested that plants sporulate (produce spores) mostly in the spring and summer (Nauman 1986, p. 182), field observations in Miami-Dade County have observed sporangia in the months of February, March, May, August, October, and December. The plants are likely fertile any time of year; however, during the dry season, sporophytes have been observed to desiccate and probably do not produce spores (Possley 2013d, pers. comm.). In Sumter County, sporangia have been observed from April through September; however, researchers suggest they are likely producing all year, with peaks in the wet season (van der Heiden 2013c, pers. comm.). For
Trichomanes punctatum
ssp.
floridanum,
specific reproductive and growth requirements, such as moisture levels needed for each stage of its life history, plant longevity, growth rates, recruitment rates, dispersal methods, and genetic variation, are currently unknown.

Organizations such as the Institute for Regional Conservation (IRC) and Fairchild Tropical Botanic Garden (Fairchild) are working together to understand the biology and life history of
Trichomanes punctatum
ssp.
floridanum.
In 2002, IRC and Fairchild collaborated with fern culture experts from Marie Selby Botanical Gardens (MSBG) in Sarasota, Florida, and tissue culture experts at the Lindner Center for Conservation and Research on Endangered Wildlife (CREW) in Cincinnati, Ohio (Gann
et al.
2009, pp. 35-36). Currently, Fairchild maintains fewer than five healthy clusters of
T. p.
ssp.
floridanum
from plants obtained in local hammocks (tropical hardwood forests) that are monitored by their organization. The success of this effort to grow healthy
T. p.
ssp.
floridanum
has yet to be determined due to several factors, including: Slow growth rates, the formation of unusual linear fronds, the susceptibility to mold, and the lack of sporulation (Possley
et al.
2013, pp. 43-45). However, researchers at CREW

have recently developed a successful method to culture
T. p.
ssp.
floridanum
in-vitro and cryopreserve (to preserve by freezing at low temperatures) sporophytes (V. Pence, submitted; Pence and Charls 2006, pp. 29-34). The new plants from CREW have recently been transferred to MSBG, and plans are under way to establish
T. p.
ssp.
floridanum
onto limestone rock, which could potentially be transferred to solution hole (see description under “Habitat” section, below) walls for eventual reintroduction to the wild (Holst 2014, pers. comm.).

It is important to note that the numerous efforts to cultivate
Trichomanes punctatum
ssp.
floridanum
ex-situ for possible future reintroduction have been only partially successful. Researchers have not been able to propagate
T. p.
ssp.
floridanum
via sexual reproduction. Although they have been able to maintain the subspecies in cultivation in the greenhouse for several months at a time, and temporarily establish rhizome growth onto limestone rock, the propagated fern eventually declines or becomes overrun with mosses. Even when there is vegetative growth, there is no sign of spore production (Holst 2014, pers. comm.).

Habitat

In southeastern North America,
Trichomanes
ssp. are considered rare because of their delicate nature and requirements for deeply sheltered habitats with almost continuous high moisture and humidity (Farrar 1993, pp. 190-197; Zots and Buche 2000, p. 203), restricting them from a more widespread pre-glaciation distribution.
Trichomanes punctatum
ssp.
floridanum
is considered strongly hygrophilous (growing or adapted to damp or wet conditions) and generally perceived as restricted to constantly humid microhabitat (Krömer and Kessler 2006, p. 57).
T. p.
ssp.
floridanum
occurs only in the United States in the State of Florida. In Florida,
T. p.
ssp.
floridanum
is known to occur only in Miami-Dade and Sumter Counties.

Both extant metapopulations occur in dense canopy habitats, with shady conditions that may be obligatory due to the poikilohydric (
i.e.,
possessing no mechanism to prevent desiccation) nature of some fern species (Krömer and Kessler 2006, p. 57). The canopy directly contributes to the surrounding humidity of an area. Dense canopies found in rockland habitats can minimize temperature fluctuations by reducing soil warming during the day and heat loss at night. In areas with greater temperature variations, as in Sumter County, this temperature minimization effect can help prevent frost damage to the interior of the hammock (FNAI 2010, p. 25). Mesic conditions are further maintained by the hammock's rounded canopy profile, which deflects winds, limiting desiccation during dry periods and reducing interior storm damage (FNAI 2010, p. 25). Changes in the canopy can impact humidity and evaporation rates, as well as the amount of light available to the understory.

In Miami-Dade County,
Trichomanes punctatum
ssp.
floridanum
is generally epipetric (a plant that grows on rocks) or epiphytic (a plant that grows non-parasitically upon another plant), typically growing in rocky outcrops of rockland hammocks, in oolitic (composed of minute rounded concretions resembling fish eggs) limestone solution holes (see description below), and, occasionally, on tree roots in limestone-surrounded areas (Phillips 1940, p. 166; Nauman 1986, p. 180; Whitney
et al.
2004, pp. 105-106; Possley 2013e, pers. comm.; van der Heiden 2014b, pers. comm.). These rockland habitats are outcrops primarily comprising marine limestone representing the distinct geological formation of the Miami Rock Ridge, a feature that encompasses a broad area from Miami to Homestead, Florida, and narrows westward through the Long Pine Key area of Everglades National Park (ENP) (Snyder
et al.
1990, pp. 233-234). Several endemic plant species have been identified to be closely associated with the rocklands of southern Florida; these plants are believed to have no adaptation for long-distance dispersal, suggesting a lengthy period of evolution on rocky substrate in southern Florida (Snyder
et al.
1990, p. 236).

Rockland hammocks are a type of rich tropical hardwood forest on upland sites in areas where limestone is very near the surface and often exposed. Once numerous throughout South Florida, these rockland hammocks have a diverse closed canopy and shrub layer, where more than 120 native tree and shrub species are known to occur, including a number of rare plant and animal species, federally listed and candidate species, South Florida endemics, and tropical species at or near the northern limit of their ranges (Phillips 1940, p. 166; Snyder
et al.
1990, p. 16; Gann
et al.
2009, p. 3). The forest floor is characterized by leaf litter with varying amounts of exposed limestone and has few herbaceous species. Rockland hammocks generally consist of larger, mature trees in the interior, while the margins can be almost impenetrable due to dense growth of smaller shrubs, trees, and vines (FNAI 2010, pp. 24-27). The canopy cover is typically very dense where
Trichomanes punctatum
ssp.
floridanum
occurs. In Miami-Dade County, the hammocks consist of a mix of temperate and tropical hardwood trees, both canopy and understory, including
Ocotea coriacea
(lancewood),
Coccoloba diversifolia
(pigeon plum),
Quercus virginiana
(live oak),
Simarouba glauca
(paradise tree),
Ficus aurea
(strangler fig), and
Sideroxylon foetidissimum
(mastic) (see Snyder
et al.
1990, p. 241, for complete list). Soils where
T. p.
ssp.
floridanum
is extant in Miami-Dade County generally consist of an uneven layer of highly organic soil overlying rock (Snyder
et al.
1990, p. 238); soils are classified as Matecumbe Muck (moderately well-drained soils that are very shallow) (Florida Geographic Data Library 2013,
http://www.fgdl.org/
). Soils from historical and extant records consist of the following soil types: Krome Very Gravelly Loam, Cardsound Silty Clay Loam-Rock Outcrop Complex, Opalocka Sand-Rock Outcrop Complex, and Dania Muck.

The limestone solution holes are considered specialized habitat within these hammock areas that host
Trichomanes punctatum
ssp.
floridanum,
as well as several other fern species (Snyder
et al.
1990, p. 247). The solution hole features that dominate the rock surface in the Miami Rock Ridge are steep-sided pits, varying in size, formed by dissolution of subsurface limestone followed by a collapse above (Snyder
et al.
1990, p. 236). Limestone solution holes vary in size, from shallow holes less than 0.5 meter (m) (1.6 feet (ft)) deep to those that cover over 100 m
2
(1,076 ft
2
) and are several meters deep (Snyder
et al.
1990, p. 238). The bottoms of most solution holes are filled with organic soils, while deeper solution holes penetrate the water table and have (at least historically) standing water for part of the year (Snyder
et al.
1990, pp. 236-238). Humidity levels are higher in and around the solution holes because of standing water and moisture retained in the organic soils. Many tropical, epipetric plant species are associated with the sinkholes and solution holes in rockland hammocks.

In Sumter County,
Trichomanes punctatum
ssp.
floridanum
is known to be epipetric, residing on limestone boulders in high atmospheric humidity hammocks (van der Heiden 2013a, pers. comm). The extant populations are located in mesic hammocks on limestone boulders 0.1-1.5 m (0.3-4.9 ft) tall (see “Current Range” section,

below). Mesic hammock is a developed evergreen hardwood and/or palm forest on soils that are rarely inundated (FNAI 2010, pp. 19-23) and commonly associated with hydric hammock and mixed wetland hardwoods. The difference between mesic hammocks and surrounding habitats is a slight difference in elevation. Mesic hammocks occur on higher ground within basin or floodplain wetlands; as patches of oak/palm forest in dry prairie or flatwoods communities; on river levees; in ecotones (transition area between two biomes or areas of distinct plant and animal groups) between wetlands and upland communities; and at the edges of lakes, sinkholes, other depressional or basin wetlands, and river floodplains where natural fires do not occur (FNAI 2010, pp. 19-23).

Recent field surveys (van der Heiden 2015a, p. 6; van der Heiden 2015b, unpublished data; van der Heiden 2015c, unpublished data) have provided additional information regarding potential suitable habitat in Sumter County. These surveys, conducted by IRC and funded by the Service, delineated suitable habitat within and around the Jumper Creek Tract of the Withlacoochee State Forest. Within surveyed areas, IRC mapped all suitable substrate found in areas having suitable canopy and hydrology to support growth of
Trichomanes punctatum
ssp.
floridanum
. The resulting map included limestone rocks and boulders in not only mesic hammock, but also hydric hammock, elevated hydric hammock, and (in a small number of instances) adjacent wetland (but non-hammock) habitats. The Service is still evaluating this information and working with IRC to further refine suitable habitat parameters for the fern in Sumter County. Despite extensive surveys through approximately 1,904 ha (4,705 ac) in and around the Jumper Creek Tract, van der Heiden (2015a, p. 9) did not find any new populations of
T. p.
ssp.
floridanum
.

Although there are several occurrences of
Trichomanes punctatum
ssp.
floridanum
in Sumter County where sunlight can be observed through the canopy, generally the habitat is shaded throughout the year, with the lowest amount of canopy cover recorded at approximately 65 percent (van der Heiden and Johnson 2014, p. 20; in Rocky Hammock).
T. p.
ssp.
floridanum
has been observed growing on small limestone rocks, as well as boulders with tall, horizontal faces with numerous other species, including rare State-listed species (
e.g., Asplenium cristatum
(hemlock spleenwort)) and widespread
Pecluma dispersa
(widespread polypody) (van der Heiden 2013b, pers. comm.; van der Heiden and Johnson 2014, pp. 15-16).

Within one occupied Sumter County hammock (Rocky Hammock), the majority of
Trichomanes punctatum
ssp.
floridanum
occur on the northern face of limestone boulders; however, those clusters found on non-north-facing limestone generally occur in close proximity to other boulders, trees, or within protected crevices (van der Heiden and Johnson 2014, p. 7). Van der Heiden and Johnson (2014, pp. 9-10) suggested that the northern aspect of limestone boulders is more often inhabited by this taxon because of the reduced exposure to sunlight, promoting cooler temperatures and higher moisture as compared to other sun-exposed sections of rock. This may also be the case for those clusters shielded by other boulders, by trees, or in crevices, allowing the plant to grow on any portion of the shielded rock as long as moisture levels remain high enough to prevent desiccation (van der Heiden and Johnson 2014, pp. 9-10). Additionally, both populations of
T. p.
ssp.
floridanum
in Sumter County grow within the northern quadrant of each hammock.

Soils of mesic hammock are sands mixed with organic matter, often containing a thick layer of leaf litter and generally well-drained. Although some areas maintain high-moisture soils due to the accumulation of leaf litter and extensive canopy cover, in general, mesic hammocks can occur across a broad gradient of soil moisture conditions, from somewhat xeric to almost hydric soils. Rock outcrops may also occur in mesic hammocks, especially where limestone is near the surface (FNAI 2010, pp. 19-23). Soil types for the extant metapopulation of
Trichomanes punctatum
ssp.
floridanum
in Sumter County include Okeelanta Muck, Frequently Flooded, and Mabel Fine Sand (
i.e.,
deep and very deep, somewhat poorly drained, slowly permeable soils that formed in sandy to clayey marine deposits, with a bouldery (abounding in rocks or stones) subsurface and 0-5 percent slopes (Florida Geographic Data Library 2013,
http://www.fgdl.org/
)). Additionally, one historical record has Adamsville Fine Sand, Bouldery Subsurface, while another population containing a questionable record from an extirpated population has what is classified as Malabar Fine Sand, Frequently Flooded.

Plant communities associated with mesic hammocks vary depending on the latitude; tropical species gradually increase in frequency from the central to southern peninsular Florida. In south Florida, some high-elevation areas dry enough to support a semi-tropical mesic hammock do exist; however, most “high hammocks” are rockland hammocks occurring on limestone (FNAI 2010, pp. 19-23).
Q. virginiana
is common in mesic hammock communities. Oak species found in these hammocks tend to possess a broader tolerance of a range of conditions than do oaks in other habitats (FNAI 2010, pp. 19-23). Mesic hammocks do not contain wetland trees, as found in hydric hammocks; however, these two hammock types often occur as intermixed stands. Because mesic hammocks are often associated with hydric hammocks, with wetlands, or as a transition to uplands, they are sensitive to hydrologic alteration in the landscape. For example, changes in flooding frequency and/or duration can kill most mesic hammock tree species, while lowered water tables can shift vegetation towards xeric species or promote wildfires, destroying the hammock (FNAI 2010, pp. 19-23). Mesic hammocks may be distinguished from rockland hammocks by the dominance of temperate species in the canopy, whereas rockland hammocks are composed of predominantly tropical woody species.

Trichomanes punctatum
ssp.
floridanum
in Sumter County can be found under a dense canopy including
Q. virginiana, Sabal palmetto
(cabbage palm),
Carpinus caroliniana
(American hornbeam),
Celtis laevigata
(sugarberry),
Acer negundo
(boxelder),
Liquidambar styraciflua
(sweetgum), and
Sapindus saponaria
(wingleaf soapberry) (van der Heiden 2013c, pers. comm.; van der Heiden and Johnson 2014, p. 19). The hammocks where
T. p.
ssp.
floridanum
has been found are also surrounded by a mosaic of wetlands dominated by
Taxodium distichum
(cypress trees). Field surveys of Sumter County populations recorded 18 canopy species in Rocky Hammock and 12 in Tree Frog Hammock (van der Heiden and Johnson 2014, p. 19). The average canopy closure for both populations in Sumter County has been estimated to be more than 75 percent, where it is heavily shaded, maintaining high humidity to reduce chances of desiccation (van der Heiden and Johnson 2014, p. 9). Van der Heiden and Johnson (2014, p. 9) speculate this dense, closed canopy can serve as a shield for
T. p.
ssp.
floridanum
to inhibit the growth of other plant species on the same part of an inhabited rock area.

Although it is believed this subspecies needs high temperatures (although likely not above 100 degrees Fahrenheit (°F); Possley 2014c, pers. comm.) and humidity, along with dense

canopy, there is limited information on optimal temperature and humidity ranges or thresholds for
Trichomanes punctatum
ssp.
floridanum
growth and survival. In Miami-Dade County where
T. p.
ssp.
floridanum
currently is found, the mean maximum temperature from 2004 to 2013 was 29.0 degrees Celsius (°C) (84.3 °F), and the mean minimum temperature for the same time period was 21.4 °C (70.5 °F) (
http://www1.ncdc.noaa.gov
). In contrast, yearly mean temperatures were lower for Sumter County with 23.4 °C (74.2 °F) recorded as the mean maximum temperature from 2004 to 2013, and 11.8 °C (53.2 °F) as the mean minimum temperature for the same time period (National Oceanic and Atmospheric Administration 2014,
http://www1.ncdc.noaa.gov
).

Recent field studies have provided some data on microhabitat conditions (
e.g.,
temperature and humidity) for
Trichomanes punctatum
ssp.
floridanum
populations in Sumter County. Van der Heiden and Johnson (2014, pp. 8, 21) found average relative humidity to be around 95 percent in both Rocky Hammock and Tree Frog Hammock, while average ambient temperature in both hammocks was approximately 21 °C (70 °F) from September 2013 to November 2013. However, during cooler periods (19-21 °C; 66-70 °F) when humidity levels dropped slightly (by approximately 2 percent), observed plant health declined, demonstrating the fragile nature of this taxon and its dependence on high-humidity conditions (van der Heiden and Johnson 2014, pp. 9, 21). Collection of humidity and temperature data within these same areas was subsequently continued through March 2015. From September 2013 to March 2015, average monthly temperatures in both hammocks were very similar and ranged from approximately 12 °C (53 °F; in January 2014) to 25 °C (78 °F; in August 2014) (van der Heiden 2015a, p. 17). The average relative humidity in both hammocks was 94.8 percent throughout the study (van der Heiden 2015a, p. 5). This type of information needs to be further explored to determine habitat requirements (
i.e.,
thresholds for humidity and temperature) for both metapopulations of this taxon.

Historical Range/Distribution

The historical range of
Trichomanes punctatum
ssp.
floridanum
included southern (Miami-Dade County; see Table 1, below) and central (Sumter County; see Table 2, below) Florida.

Miami-Dade County

In Miami-Dade County, the historical range of this subspecies extended from its southern limit in Royal Palm Hammock (now part of ENP) northeast to Deering-Snapper Creek Hammock, which includes the modern-day site of Smather's Four Fillies Farm residential area, near R. Hardy Matheson Preserve (derived from Gann
et al.
2002, pp. 552-554), a range of at least 45 square kilometers (km
2
) (17 square miles (mi
2
)). Plants in Miami-Dade were known to historically occur in at least 11 hammocks: Deering-Snapper Creek Hammock, Castellow Hammock, Silver Palm Hammock (also known as Caldwell), Ross Hammock, Royal Palm Hammock (in ENP), Hattie Bauer Hammock, Shields Hammock, Nixon-Lewis Hammock, Fuchs Hammock, Addison Hammock (in the Deering Estate at Cutler), and Matheson Hammock. In the 1980s,
T. p.
ssp.
floridanum
was also documented in Meissner Hammock and Cox Hammock (now part of the tourist attraction “Monkey Jungle”) (Small 1918, p. 6; Small 1921, p. 211; Morton 1963 p. 90; Fairchild Tropical Garden 1968, p. 1; Nauman 1986 p. 182; Gann
et al.
2002, pp. 552-554; Gann 2013,
http://regionalconservation.org/ircs/database/plants/IRCSpAccount.asp?TXCODE=Tricpuncflor&GENUS=Trichomanes&SPECIES=punctatum&Author=Poir.&INFRA1=subsp.&INFRA1NAME=
ssp.
floridanum&INFRA1AUTHOR=Wess.%20Boer&CommonNames=Florida%20bristle%20fern
).

J.K. Small documented
Trichomanes punctatum
ssp.
floridanum
in 1901 at Deering-Snapper Creek. J.K. Small made subsequent collections of the subspecies in and around Miami-Dade County including one in 1903, probably located in or near present-day Castellow Hammock (Gann 2014d, pers. comm.). A.A. Eaton collected additional specimens from Castellow Hammock in 1903. More recent observations of
T. p.
ssp.
floridanum
in Castellow Hammock include documentation by G. Gann and K. Bradley in the late 1990s (Bradley and Gann 1999), and subsequent observations by J. Possley and others (Gann
et al.
2002, pp. 552-554; Possley
et al.
2013, pp. 43-45).
T. p.
ssp.
floridanum
was collected by A.A. Eaton in Silver Palm Hammock in 1903 and reported again in 1980; however, the 1980 report was not confirmed. The fern was collected from Ross Hammock by J.K. Small and colleagues in 1906. Since then, part of this hammock has been damaged, and what remains is currently protected as a Miami-Dade County Environmentally Endangered Lands (EEL) Preserve. In 1909, the subspecies was collected in Royal Palm Hammock (also known as Paradise Key), now within ENP, and later reported by W.E. Stafford in 1917 (Stafford 1919, p. 386; Gann
et al.
2002, pp. 552-554).

Several collections of
Trichomanes punctatum
ssp.
floridanum
were made in Miami-Dade in 1915, including: Hattie Bauer Hammock, Shields Hammock, Nixon-Lewis Hammock, Fuchs Hammock, and Deering-Snapper Creek Hammock. Hattie Bauer Hammock, now a Miami-Dade County conservation area, has numerous subsequent collection records by Small (1915, 1916), Correll (1936), and McFarlin (1934, 1940) as cited by Gann 2013,
http://regionalconservation.org/ircs/database/plants/IRCSpAccount.asp?TXCODE=Tricpuncflor&GENUS=Trichomanes&SPECIES=punctatum&Author=Poir.&INFRA1=subsp.&INFRA1NAME=
ssp.
floridanum&INFRA1AUTHOR=Wess.%20Boer&CommonNames=Florida%20bristle%20fern
. The last known collection in Hattie Bauer Hammock was recorded in 1960, by T. Darling, Jr. It was subsequently reported as extirpated by Gann
et al.
(2002, pp. 552-554), until it was rediscovered in this hammock in 2011 by Possley (Possley
et al.
2013, pp. 1-2). Shields Hammock was destroyed prior to 1991 (Cressler 1991, Handwritten Notes). Fuchs Hammock is now part of the Fuchs Hammock Preserve (Gann
et al.
2002, pp. 552-554), and the subspecies was vouchered (pressed plant samples taken for future reference) again in 1954, by L. J. Brass; in 1959, by T. Darling Jr.; and in 1969, by F.C. Craighead (The Institute for Regional Conservation, Herbarium Specimens, Floristic Inventory of South Florida Database, September 12, 2007).
T. p.
ssp.
floridanum
was also vouchered in Fuchs Hammock in 1993, following Hurricane Andrew (1992) by A. Cressler (Cressler 12 February 1993, handwritten notes), and it has been more recently observed by Possley and others over the years (Gann
et al.
2002, pp. 552-554; Possley
et al.
2013, pp. 43-45).
T. p.
ssp.
floridanum
was observed by G. N. Avery in 1983 in Meissner Hammock (immediately adjacent to Fuchs Hammock) and was since vouchered by K. Bradley in 1997 and 2002 and also observed by others (Gann
et al.
2002, pp. 552-554; Possley
et al.
2013, pp. 43-45).

In 1916, J.K. Small reported
Trichomanes punctatum
ssp.
floridanum
in Addison Hammock, now located within Deering Estate at Cutler,

currently Miami-Dade County Park; however, these reports were never vouchered (J.K. Small 1916; Gann
et al.
2002, pp. 552-554). Surveys in recent years have yet to find any populations of
T. p.
ssp.
floridanum
in Deering Estate at Cutler, Matheson Hammock, or Silver Palm Hammock (Possley 2013i, pers. comm.). The subspecies was last reported from Cox Hammock in 1989, by A. Cressler, where plants were observed in a sinkhole in the tourist attraction “Monkey Jungle” (Cressler 1991, handwritten notes); it is not known if these plants still exist. Cox Hammock is located about 1.6 km (1.0 mi) northeast of Castellow Hammock Park. Additional hammocks existing today where the taxon formerly occurred include Ross and Royal Palm Hammock (in ENP) and Deering-Snapper Creek Hammock. A section of Deering-Snapper Creek Hammock was destroyed in 1912-1913, when the Snapper Creek Canal was constructed. Dredging of this canal drastically altered the water table in the area, depleting the freshwater springs, while a large spoil berm from excavation of the canal destroyed habitat (Metro-Dade County Park and Recreation Department 1991, p. 10). Other hammocks in the historical range that are presumed destroyed include Nixon Lewis Hammock, which is partially destroyed (Gann 2013,
http://regionalconservation.org/ircs/database/plants/IRCSpAccount.asp?TXCODE=Tricpuncflor&GENUS=Trichomanes&SPECIES=punctatum&Author=Poir.&INFRA1=subsp.&INFRA1NAME=
ssp.
floridanum&INFRA1AUTHOR=Wess.%20Boer&CommonNames=Florida%20bristle%20fern
) and a station presumably near the Matheson Hammock Park vouchered by G. Peterson in 1940.

Table 1—Summary of Historical Reports and Current Population and Hammock Status of Each Trichomanes Punctatum ssp. Floridanum Location in Miami-Dade County

[Gann
et al.
2002; The Institute for Regional Conservation, Herbarium Specimens, Floristic Inventory of South Florida Database, September 12, 2007; Florida Natural Areas Inventory element occurrences 9/12/2013; Possley 2013c, i-j, 2014a-c; Possley 2013, 2014a pers. comm.; Gann 2013, pers. comm.; van der Heiden 2013e, pers. comm.; Gann 2014a-f, pers. comm.; Gann
et al.
2001-2014). Population locations (hammocks) are numbered in chronological order by
T. p.
ssp.
floridanum
initial discovery date.]

No.
Population location

Year(s) of
initial report(s)

Observer

Number of specimens
collected

Current
population status

Current
hammock status

1
Deering-Snapper Creek Hammock-Smather's Four Fillies Farm (R. Hardy Matheson Preserve)
1901
J.K. Small, G.V. Nash
3
Extirpated
Protected Area, Partially Destroyed.

1915
J.K. Small, C.A. Mosier
1

2
Castellow Hammock
1903
J.K. Small, J.J. Carter
2
Extant
Protected Area.

1903
A.A. Eaton
4

3
Silver Palm Hammock
1903
A.A. Eaton
1
Extirpated
Protected Area.

4
Ross Hammock
1906
J.K. Small, J.J. Carter
2
Extirpated
Protected Area, Partially Destroyed.

5
Royal Palm Hammock (ENP); aka Paradise Key
1909
J.K. Small, J.J. Carter
2
Extirpated
Protected Area.

1917
W.E. Stafford
None

1915
J.K. Small, C.A. Mosier
2

1915
J.K. Small
3

1915
J.K. Small, C.A. Mosier, G.K. Small
5

6
Hattie Bauer Hammock (Orchid Jungle)
1916
J.K. Small
1
Extant
Protected Area.

1934
J.B. McFarlin
2

1936
D.S. Correll
2

1940
J.B. McFarlin
1

1960
T. Darling Jr.
1

7
Shields Hammock
1915
J.K. Small, C.A. Mosier, G.K. Small
1
Extirpated
Destroyed.

8
Nixon-Lewis Hammock
1915
J.K. Small, C.A. Mosier
1
Extirpated
Protected Area, Partially Destroyed.

9
Fuchs Hammock (Sykes Hammock)
1915
J.K. Small, C.A. Mosier
1
Extant
Protected Area.

1954
L.J. Brass
1

1959
T. Darling Jr.
1

1969
A.F. Clewell, F.C. Craighead
1

10
Deering Estate at Cutler (Addison Hammock)
1916
J.K. Small
None

Unconfirmed
1

Protected Area.

11
Matheson Hammock Park
1940
G. Peterson
2

Unconfirmed
2

Protected Area.

12
Meissner Hammock
1983
G.N. Avery
None
Extant
Protected Area.

13
Monkey Jungle (Cox Hammock)
1989
A. Cressler
None

Unknown
3

Privately Owned, Partially Destroyed.

1
Initial report is questionable.

2
Precise location of sample and associated report is questionable.

3
It is not known whether the subspecies still occurs here.

Sumter County

In Sumter County, early collections and herbarium label data for
Trichomanes punctatum
ssp.
floridanum
are not accurate or precise in their location descriptions. The first documented collection in 1936, by R.P. St. John, simply states that
T. p.
ssp.
floridanum
was found 11.26 km (7.0 mi) east of Floral City. This collection is close to the extant populations in Sumter (in Rocky Hammock within Withlacoochee State Forest), which is east-southeast of Floral City, and is thought to be the location where
T. p.
ssp.
floridanum
existed on private land until it was cleared for cattle sometime after 1983. A specimen found 3 years later, by J.B. McFarlin in 1939, was originally thought to be
T. sphenoides;
the herbarium label data described this collection as “South of Floral City, Florida.
T. sphenoides
is a misapplied synonym for
T. p.
ssp.
floridanum
according to FNAI. This is the only known station in the United States.” It is believed that these label data may have been incorrectly recorded, indicating a direction of south from Floral City, when it should have been east. In all likelihood, McFarlin's collection probably referred to the population in the Wahoo area, where St. John previously collected because he states his collection was from the same locality where it was originally found in 1936. The specimen found by McFarlin eventually led to reports of the taxon in Citrus County (Wherry 1964, p. 232; Nelson 2000, p. 81); however, this was never confirmed beyond the initial report. Systematic surveys have not been conducted in Citrus County; therefore, the only documented occurrences of
T. p.
ssp.
floridanum
in this region of Florida have been in Sumter County, just north of Wahoo and east of the Withlacoochee River.

Several years later, in 1954, R. Garrett collected
Trichomanes punctatum
ssp.
floridanum
southeast of Floral City. It is thought to be the same location where St. John and McFarlin made their previous collections; however, label data were again minimal and the exact location is uncertain. In 1959, T. Darling Jr. found this subspecies near Floral City, 11.26 km (7.0 mi) south near a location called Battle Slough. This record has never been confirmed because it is located on private property. Another specimen was found in 1963, by O. Lakela in an area known as Indian Field Ledges. Lakela recorded his location and collection to be west of Withlacoochee River off State Road #48. This information is believed to be incorrect based on a site visit by Darling (1961, p. 7), stating that the Indian Field Ledges is north of Wahoo, a locality east of the Withlacoochee River.
T. p.
ssp.
floridanum
was not found again in Sumter County until 1983, when SW. Leonard made a collection on private property known as Rocky Point, north of Wahoo. This is presumed to be the same location where St. John, McFarlin, and Garrett collected their specimens. This population is now extirpated.

Table 2—Summary of Presumed Extirpated, Extirpated, and Unconfirmed Trichomanes Punctatum ssp. Floridanum Populations in Sumter County

[Gann
et al.
2002; The Institute for Regional Conservation, Herbarium Specimens, Floristic Inventory of South Florida Database, September 12, 2007; Florida Natural Areas Inventory Element Occurrences 9/12/2013; van der Heiden 2013d, 2014a, pers. comm.; Gann
et al.
2001-2014). Population locations (hammocks) are numbered in chronological order by
T. p.
ssp.
floridanum
initial discovery date.]

No.
Population location
Year of initial report
Observer

Number of specimens
collected

Current
population status

Current
hammock status

1

11.26 km (7 mi) East of Floral City
1

1936
R.P. St. John
1
Presumed Extirpated
Privately Owned, Presumed Destroyed.

2

Floral City Area
1

1939
J.B. McFarlin
1

Unconfirmed
2

Unknown.

3

Southeast of Floral City
1

1954
R. Garret
1
Presumed Extirpated
Privately Owned, Presumed Destroyed.

4

Floral City, 11.26 km (7 mi) south (Battle Slough)
1

1959
T. Darling Jr.
1

Unconfirmed
2

Privately Owned, Unknown.

5

East of Withlacoochee River, off State Road #48 (Indian Field Ledges)
1

1963
O. Lakela
1
Extirpated
Protected Area.

6
Rocky Point, (north of Wahoo)
1983
S.W. Leonard
1
Extirpated
Privately Owned, Destroyed.

1
Sumter County collections and herbarium label data for
Trichomanes punctatum
ssp.
floridanum
are inaccurate in location descriptions.

2
Initial report is questionable.

Current Range

The extant metapopulation of
Trichomanes punctatum
ssp.
floridanum
in Miami-Dade County is approximately 400 km (249 mi) south of the extant metapopulation in Sumter County. Both metapopulations of
T. p.
ssp.
floridanum
are located entirely on public lands (see Table 3, below). In general,
Trichomanes punctatum
ssp.
floridanum
occurs in small areas within each hammock.

Table 3—Summary of Known Extant Occurrences of Trichomanes punctatum ssp. floridanum.
[Possley 2013, pp. 1-2; Dozier 2014, Pers. Comm.; van der Heiden and Johnson 2014, pp. 5, 26]

Metapopulation
location
(county)

Population location
Land ownership

Number of
subpopulations

Status

Miami-Dade
Meissner Hammock
State
2
Extant.

Miami-Dade
Fuchs Hammock Preserve.
County
4
Extant.

Miami-Dade
Castellow Hammock Park
County
3
Extant.

Miami-Dade
Hattie Bauer Hammock
County
1
Extant.

Sumter
Rocky Hammock, Withlacoochee State Forest's Jumper Creek Tract
State
1
Extant.

Sumter
Tree Frog Hammock, Withlacoochee State Forest's Jumper Creek Tract
State
1
Extant.

Miami-Dade County

The four populations that constitute the Miami-Dade County metapopulation are located in urban preserves managed by the County's EEL Program and the Natural Areas Management (NAM) Division of Miami-Dade County's Parks, Recreation and Open Spaces (PROS) Department (see
Factor A,
Conservation Efforts to Reduce Habitat Destruction, Modification, or Curtailment of Its Range, below). These EEL Preserves include: Castellow Hammock Park (39.5 hectares (ha)) (97.6 acres (ac)), Hattie Bauer Hammock (5.7 ha (14.0 ac)), Fuchs Hammock Preserve (15.7 ha (38.8 ac)), and Meissner Hammock (4.1 ha (10.1 ac)). Three of these preserves (76 percent of the land area) are owned by the County; the fourth, Meissner Hammock (24 percent), is owned by the State and leased to the County (Dozier 2014, pers. comm.). The population in Fuchs Hammock Preserve includes a new subpopulation that was found in July 2013 (Possley
et al.
2013, pp. 43-45). Fuchs and Meissner Hammocks are immediately adjacent to each other, and Castellow Hammock Park is 10.5 km (6.5 mi) to the northeast. Although the fern was thought to be extirpated from Hattie Bauer Hammock in 1960, another population was re-discovered there in 2011 (8 ha (20 ac)) (Possley
et al.
2013, pp. 43-45). Hattie Bauer Hammock is 4.02 km (2.5 mi) south of Castellow Hammock and approximately 8.05 km (5 mi) northeast of Fuchs and Meissner Hammocks.

No comprehensive survey has been conducted in rockland hammocks in Miami-Dade County where suitable
Trichomanes punctatum
ssp.
floridanum
habitat has been identified. Although these areas have been extensively explored by numerous botanists and plant enthusiasts, including sites where the subspecies was formerly found, due to the cryptic nature of this plant it may have been overlooked and new occurrences may yet be discovered (Possley 2013e, pers. comm.; van der Heiden 2013c, pers. comm.). Surveys conducted in the late 1990s, and as late as 2010, did not find
T. p.
ssp.
floridanum
in Silver Palm Hammock (Gann
et al.
2002, pp. 552-554; Possley 2013f, pers. comm.). A sporophyte sample was collected in Nixon-Lewis Hammock by Small and Mosier in 1915; however, due to extensive disturbance of this hammock, subsequent surveys conducted in 2006, by IRC, could not find the taxon (Bradley and Gann 2005, unpublished data). Over the years, IRC has completed systematic surveys in ENP in Royal Palm Hammock and other hammocks on Long Pine Key (also in ENP); however, sporophytes have not been found there (Gann
et al.
2009; pp. 1-66). In 2003, based on historical records, staff from ENP and IRC surveyed Royal Palm Hammock for
T. p.
ssp.
floridanum
without success; subsequent surveys conducted in rockland hammocks throughout Long Pine Key for other rare plants also were not successful in finding
T. p.
ssp.
floridanum
(Sadle 2013, pers. comm.).

Sumter County

The Sumter County metapopulation consists of two extant populations of
Trichomanes punctatum
ssp.
floridanum
that have been reported north of Wahoo, in the Withlacoochee State Forest's Jumper Creek Tract; these populations are located in Rocky Hammock (located on 44 boulders) and Tree Frog Hammock (located on 4 boulders) (van der Heiden and Johnson 2014, p. 7). The population in Tree Frog Hammock was discovered as recently as April 2013, during regional surveys (van der Heiden 2013c, pers. comm.). Two additional populations were known from private land just south of the State Forest; however, these populations were subsequently extirpated due to the clearing of land for agriculture by the property owner (van der Heiden 2013c, pers. comm.).

Recent GIS analyses show the soil type associated with known extant occurrences of
Trichomanes punctatum
ssp.
floridanum
in the northern metapopulation to be Okeelanta Muck, Frequently Flooded; this soil covers approximately 1,478 ha (3,652 ac) in Sumter County. However, not all of these areas have been systematically surveyed. Surveys were conducted of a boulder field within Withlacoochee State Forest's Jumper Creek Tract (called the Indian Field Ledges) in August 2007 and April 2013 and were unsuccessful (van der Heiden 2013c, pers. comm.). The discovery of new populations may be possible in the area. Indeed, the population of this subspecies in Jumper Creek's Tree Frog Hammock is a new population that was discovered in April 2013, during additional hammock surveys within Withlacoochee State Forest and the surrounding area (van der Heiden 2013c, pers. comm.). However, IRC recently conducted extensive surveys through approximately 1,904 ha (4,705 ac) in and around the Jumper Creek Tract, and no additional populations of
T. p.
ssp.
floridanum
were located (van der Heiden 2015a, p. 9).

It is also possible that other subpopulations may exist in Sumter County. Indian Ledges, a hammock located on private land near Jumper Creek (not to be confused with Indian Field Ledges), just north of Wahoo, is believed to be suitable for
Trichomanes punctatum
ssp.
floridanum,
including a dense canopy and appropriate soil (Deangelis 2014a-b, pers. comm.). Over the years, many rare ferns and orchids have been observed in the Indian Ledges Hammock; unfortunately, this hammock was heavily damaged by hurricanes in 2004 (Deangelis 2014a, pers. comm.).

Portions of the Southwest Florida Water Management District (SWFWMD) property within the Green Swamp, more than 40.23 km (25 miles) southeast of the Jumper Creek Tract in Withlacoochee State Forest, may also contain appropriate habitat for
Trichomanes punctatum
ssp.
floridanum
based on existing habitat features such as dense canopy, high humidity microclimates, mesic hammock, and limestone outcroppings (Elliott 2014, pers. comm.). The SWFWMD property within the Green Swamp is the only area where land alteration has not occurred in Sumter

County (11,343 ha (28,030 ac)). Portions of Green Swamp owned by the SWFWMD also extend into three other counties: Lake, Polk, and Pasco. Future survey efforts, coordinating with local land owners and conservation organizations in this area, may prove successful in finding new populations of
T. p.
ssp.
floridanum.

Population Estimates and Status

Trichomanes punctatum
ssp.
floridanum
grows in dense mats and is rhizomatous (a horizontal stem that often sends out root-like structures from its nodes). Fronds are scattered in matted clusters along the stems, making it difficult to count clusters, or groups of plants in the same location, and nearly impossible to accurately count individual plants (Nelson 2000, p. 79). This issue has been encountered in other
Trichomanes
species, such as
Trichomanes boschianum
(Appalachian bristle fern) (Hill 2003, p. 11). As such, populations are typically described by the number of clusters (
i.e.,
groups of plants in various sinkholes, on tree roots, on boulders) and the total area covered by the cluster.

Miami-Dade County

In Miami-Dade County, there are four populations of the fern with a total of 10 subpopulations (
i.e.,
nine solution holes and one rocky outcropping on a tree root). Overall, this taxon occurs in small areas (
i.e.,
less than 0.5 ha (1.2 ac)) at each site, with 88 percent of the total area in three subpopulations in Castellow Hammock. Recent surveys (see Table 4, below) in Miami-Dade by Fairchild (Possley 2013, pp. 1-2) found the fern covering a total area of approximately 9.92 m
2
(106.56 ft
2
) (Possley 2013, pp. 1-2).

Table 4—Area Covered by Each of 10 Known Subpopulations of Trichomanes punctatum ssp. floridanum in Miami-Dade County, October and November 2013
[(Possley 2013, pp. 1-2) and in Sumter County, December 2013 (van der Heiden and Johnson 2014, pp. 7, 14)]

Metapopulation
Population
Subpopulation

Estimated area covered

(m
2
)

Number of
clusters

Miami-Dade
Hattie Bauer Hammock
Hole (no tag)
0.078
2-10

Miami-Dade
Fuchs Hammock
Hole 532
0.017
2-10

Miami-Dade
Fuchs Hammock
Hole 533
0.038
2-10

Miami-Dade
Fuchs Hammock
Hole 1431
0.128
2-10

Miami-Dade
Fuchs Hammock
Root 1430
0.047
1

Miami-Dade
Meissner Hammock
Hole 2319
0.145
2-10

Miami-Dade
Meissner Hammock
Hole 3337
0.713
2-10

Miami-Dade
Castellow Hammock
Hole 2332
4.688
11-100

Miami-Dade
Castellow Hammock
Hole 2331
3.925
11-100

Miami-Dade
Castellow Hammock
Hole 944
0.141
2-10

Miami-Dade County Total

9.920

Sumter
Rocky Hammock
N/A
4.355
44

Sumter
Tree Frog Hammock
N/A
0.132
4

Sumter County Total

4.487

TOTAL Area Covered

14.407

The largest known population of
Trichomanes punctatum
ssp.
floridanum
in Miami-Dade County is located at Castellow Hammock (Possley
et al.
2013, p. 43), where it occurs in three of the larger subpopulations. In October of 2011, field surveys revealed extensive desiccation of this population after intensive nonnative vegetation removal (Possley 2013g, pers. comm.); however, by November 2013, these plants had recovered, and the total area covered by all clusters (
i.e.,
two or more plants next to each other) was estimated at 8.754 m
2
(94.227 ft
2
). Meissner Hammock has two subpopulations; the clusters in this hammock cover an area of 0.858 m
2
(9.235 ft
2
) and are considered healthy, with no signs of desiccation (Possley
et al.
2013, pp. 43-45). There is one subpopulation in Hattie Bauer Hammock covering approximately 0.78 m
2
(8.4 ft
2
), and three subpopulations of
T. p.
ssp.
floridanum
at Fuchs Hammock, with an additional one that was discovered in July 2013, totaling an area of 0.230 m
2
(2.476 ft
2
) (Possley 2013, pp. 1-2; Possley
et al.
2013, pp. 43-45).

Sumter County

In Sumter County, the Rocky Hammock subpopulation contains 44 clusters, while the newly discovered subpopulation (Tree Frog Hammock) is much smaller with only 4 clusters observed (van der Heiden and Johnson 2014, p. 7). Average cluster size for Rocky Hammock is estimated at 4.355 m
2
(46.877 ft
2
) and 0.132 m
2
(1.421 ft
2
) for Tree Frog Hammock.

Summary of Comments and Recommendations

In the proposed rule published on October 9, 2014, we requested that all interested parties submit written comments on the proposal by December 8, 2014. We also contacted appropriate Federal and State agencies, scientific experts and organizations, and other interested parties and invited them to comment on the proposal. Newspaper notices inviting general public comment were published in the
Miami Herald.
We did not receive any requests for a public hearing. All substantive information provided during comment periods has either been incorporated directly into this final determination or addressed below.

Peer Reviewer Comments

In accordance with our peer review policy published on July 1, 1994 (59 FR 34270), we solicited expert opinion from five knowledgeable individuals with scientific expertise that included familiarity with
Trichomanes punctatum
ssp.
floridanum
and its habitat, biological needs, and threats. We received responses from all five of the peer reviewers.

We reviewed all comments received from the peer reviewers for substantive issues and new information regarding the listing of
Trichomanes punctatum
ssp.
floridanum.
The peer reviewers

generally concurred with our methods and conclusions and provided additional information, clarifications, and suggestions to improve the final rule.

(1)
Comment:
One peer reviewer noted that he was unaware of any documentation that
Trichomanes punctatum ssp. floridanum
formed gemmae, as stated in the proposed rule. He commented that the works cited were in reference to other species of
Trichomanes
and Hymenophyllaceae, in general. Also, the peer reviewer pointed out a reference (Hughes 2014) in the proposal that the two metapopulations have no observable genetic differences. The peer reviewer noted that, in the Life History section, the proposal states many traits of the subspecies, such as “genetic variation,” are unknown, which contradicts the data from Hughes.

Our Response:
We appreciate this information and have corrected and updated the rule as follows: (1) We removed the phrase that stated
Trichomanes punctatum
ssp.
floridanum
produces gemmae; and (2) the term genetic variation has been removed from a sentence discussing specific reproductive and growth requirements that are unknown for the subspecies, as it conflicted with previous information within the proposed rule.

(2)
Comment:
Two peer reviewers noted that, under the Species Description section, the proposed rule incorrectly compares physical characteristics of
Trichomanes punctatum
ssp.
floridanum
with “other bryophytes.” The phrase should only read “bryophytes,” not “other bryophytes.”

Our Response:
The word “other” has been deleted from the text within the Species Description section because
Trichomanes punctatum
ssp.
floridanum
is a fern and not a bryophyte.

(3)
Comment:
One peer reviewer noted, under the Life History section, that although it is true that the sporophyte form is recognizable and spores are invisible to the naked eye, that sentence does not align with the previous thought in the paragraph that there are two stages, a sporophyte and a gametophyte stage.

Our Response:
We have restructured the sentence and noted that the gametophyte form is cryptic and invisible to the naked eye.

(4)
Comment:
One peer reviewer questioned why the two extant populations in Sumter County (that are listed in Table 3) are not listed in Table 2.

Our Response:
Table 2 is a composite of populations that are presumed extirpated, extirpated, or unconfirmed (where the report was questionable). Table 3 is a summary of the known extant occurrences of
Trichomanes punctatum
ssp.
floridanum.
The title of Table 2 has been modified for clarity in the final rule.

(5)
Comment:
One peer reviewer noted that numerous efforts to cultivate
Trichomanes punctatum
ssp.
floridanum
ex-situ for possible future reintroduction have only been partially successful and provided information on ex-situ reproduction efforts. The reviewer noted that, given the problems with ex-situ reproduction, it is critical the extant wild populations be protected to the greatest extent possible.

Our Response:
We have added text explaining propagation challenges and the importance of protecting extant populations in the wild.

Comments From the State

We received one comment from the Florida Natural Areas Inventory regarding a discrepancy between Table 2 and Table 3. That comment is addressed above under
Peer Reviewer Comments
in our response to Comment (4).

Public Comments

We received eight public comments, three of which were from the same individual, directly addressing the proposed listing. Most commenters suggested technical corrections pertaining to the Background and Summary of Factors Affecting the Species sections of the proposed rule, scientific names, species biology, and citations. Some commenters suggested we include additional information and correct minor errors. We did not receive any requests for a public hearing. The comments are appreciated, and most have been incorporated into the appropriate sections of the final rule.

(6)
Comment:
Two commenters noted an inaccurate statement in the proposed listing rule that states “The life cycle of ferns is not well known” (Woodmansee, 2013, pers. comm.). One of these commenters also noted that the second part of the same sentence mentions the life history of
Trichomanes punctatum
ssp.
floridanum
and then includes other members of the genus, which is inconsistent. One of these commenters also noted that the next sentence in this paragraph is incorrect and provided edits to describe the gametophyte form and the sporophyte form.

Our Response:
We revised the language regarding the life cycle of the
Trichomanes punctatum
ssp.
floridanum
in the Life History section from not well known to not commonly understood, as suggested by one of the commenters. The second part of the sentence, which includes information on other members of the genus
Trichomanes,
is unnecessary and has been removed. We have also revised the last sentence in that paragraph to best describe the gametophyte and sporophyte forms.

(7)
Comment:
One commenter noted that
Trichomanes punctatum
ssp.
floridanum
bristles do not protrude from the sporangia, but rather one bristle protrudes from each soral involucre, which is the tube that also houses the sporangia.

Response:
We have corrected this information in the Background section of this final rule.

(8)
Comment:
Two commenters noted that the four populations of
Trichomanes punctatum
ssp.
floridanum
within the urban preserves of Miami-Dade County are cooperatively managed by Miami-Dade County's EEL Program as well as the NAM Division of Miami-Dade County. One of these commenters suggested specific edits to sections about the EEL Program and the EEL Covenant Program. Both commenters provided additional information and clarification about the impacts of Hurricane Andrew on Hattie Bauer Hammock and the recovery of the hammock.

Our Response:
We agree that the NAM Division of the Miami-Dade County PROS Department and the EEL Program are significant local partners in the conservation of
Trichomanes punctatum
ssp.
floridanum.
As such, their efforts have been acknowledged in the final rule. We have incorporated suggested edits about the EEL Program, the EEL Covenant Program, and Hattie Bauer Hammock.

(9)
Comment:
A commenter provided information clarifying the historical range of the subspecies. The text in the proposed rule reads “In Miami-Dade, the range of this subspecies extended from Royal Palm Hammock (now in Everglades National Park (ENP)) at its southern limit, northeast to Snapper Creek Hammock, which is located in R. Hardy Matheson Preserve.” The reviewer noted that portions of historical Snapper Creek are now developed and are a residential community called Smather's Four Fillies Farm, owned by the University of Miami. Smather's Four Fillies Farm is located in the northwestern 6.5 acres of what was historical Snapper Creek Hammock.

Our Response:
We modified the historical range of the subspecies to

include the additional description of the Smather's Four Fillies Farm residential development within the Background section of the final rule.

(10)
Comment:
One commenter noted the proposed listing rule states, in the Species Description section, that the subspecies does not have roots and then later states, in the Life History section, that the subspecies sends out roots and shoots. The commenter requested clarification on this issue.

Response:
The first paragraph in the Species Description section has been modified to state that
Trichomanes punctatum
ssp.
floridanum
is mat-forming, has root-like structures, and contains trichomes. The Life History section has been modified to reflect that
T. punctatum
ssp.
floridanum
is rhizomatous (having a horizontal stem and scale leaves, bearing aerial shoots from its tips, and producing root-like structures from its undersurface).

(11)
Comment:
One commenter noted that the proposed listing states the subspecies needs high temperatures and humidity for optimum growth. The commenter remarked that this information is vague and temperatures above 100 °F may be harmful to the subspecies.

Response:
We have modified our statements regarding suitable temperatures for
Trichomanes punctatum
ssp.
floridanum.
In addition, we have included new humidity and temperature data recorded in two Sumter County hammocks where
Trichomanes punctatum
ssp.
floridanum
is found.

(12)
Comment:
One commenter reported that Ross Hammock continues to exist and was not destroyed by a hurricane in 1935. The same commenter reported the canopy of Hattie Bauer has also recovered after Hurricane Andrew.

Response:
We have corrected these statements in the Background section of this final rule.

(13)
Comment:
One commenter noted that we cannot definitively state that
Trichomanes punctatum
ssp.
floridanum
is extirpated outside of the four known populations in Miami-Dade County. It is possible that gametophytes or undiscovered sporophytes exist outside the known extant range, particularly in the “Monkey Jungle” (Cox Hammock) area.

Response:
We have revised this statement in the Summary of Factors Affecting the Species section in this final rule.

Summary of Changes From the Proposed Rule

Based on the information we received from peer reviewers and public commenters, we made the changes listed below. Additional minor corrections and edits were made in the text of the rule. We also incorporated new temperature, humidity, and survey information from a recent study conducted by the IRC in Sumter County and added information about the Clean Water Act (CWA; 33 U.S.C. 1251
et seq.
) under
Factor D. The Inadequacy of Existing Regulatory Mechanisms.

Background Section

(1) We modified the information in the rule regarding the relationship between the bristles and the sporangia of
Trichomanes punctatum
ssp.
floridanum
and their functions.

(2) We clarified the sentence regarding the visibility of the sporophyte and the gametophyte of
Trichomanes punctatum
ssp.
floridanum.

(3) We clarified information regarding the historical extent of the subspecies to include the addition of the current-day residential community, Smather's Four Fillies Farm, to the description of the Snapper Creek Hammock historical area.

(4) We added the NAM Division of Miami-Dade County's PROS Department as cooperative managers of EEL's preserves and clarified the difference between the EEL Program and the EEL Covenant Program.

(5) We clarified that
Trichomanes punctatum
ssp.
floridanum
does not have roots and that the subspecies is rhizomatous.

(6) We added information regarding challenges to propagation and the importance of protecting extant populations in the wild.

Summary of Factors Affecting the Species Section

(1) We revised the information about the impacts of the hurricane of 1935 on the habitat at Ross Hammock and the impacts of Hurricane Andrew on Hattie Bauer Hammock and
Trichomanes punctatum
ssp.
floridanum.
We also included additional information about the recovery and restoration of that habitat in Hattie Bauer Hammock after Hurricane Andrew.

(2) We added information regarding the potential existence of
Trichomanes punctatum
ssp.
floridanum
in Miami-Dade County outside of the four known populations, particularly in “Monkey Jungle” (Cox Hammock).

Summary of Factors Affecting the Species

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

Information pertaining to
Trichomanes punctatum
ssp.
floridanum
in relation to the five factors provided in section 4(a)(1) of the Act is discussed below. In considering what factors might constitute threats, we must look beyond the mere exposure of the species to the factor to determine whether the species responds to the factor in a way that causes actual impacts to the species. If there is exposure to a factor, but no response, or only a positive response, that factor is not a threat. If there is exposure and a negative response, the factor may be a threat, meaning that it may drive or contribute to the risk of extinction of the species such that the species warrants listing as an endangered or threatened species as those terms are defined by the Act. This does not necessarily require empirical proof of a threat. The combination of exposure and some corroborating evidence of how the species is likely impacted could suffice. The mere identification of factors that could impact a species negatively is not sufficient to compel a finding that listing is appropriate; we require evidence that these factors are operative threats that act on the species to the point that the species meets the definition of an endangered or threatened species under the Act.

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

Habitat modification and destruction, caused by human population growth and development, agricultural conversion, regional drainage, and canal installation, have impacted the range and abundance of
Trichomanes punctatum
ssp.
floridanum.
Secondary effects from hydrology and canopy changes have resulted in changes in humidity, temperature, and existing water levels; loss of natural vegetation; and habitat fragmentation. The modification and destruction of habitat where
T.p.
ssp.
floridanum
was once

found has been extreme in most areas of Miami-Dade County; while they have been less dramatic in Sumter County, clearing of land for agricultural conversion and historical logging has resulted in very few areas where the habitat has not been modified. These threats are discussed in detail below.

Human Population Growth, Development, and Agricultural Conversion

Miami-Dade County
—Rockland hammocks are considered imperiled both locally and globally, with a limited distribution and an FNAI ranking of G2 (imperiled globally because of rarity (6 to 20 occurrences or fewer than 3,000 individuals) or because of vulnerability to extinction due to some natural or manmade factor)/S2 (either very rare and local in Florida (21-100 occurrences or fewer than 10,000 individuals) or found locally in a restricted range or vulnerable to extinction from other factors)) (FNAI 2010, pp. 24-26, FNAI 2013). The tremendous development and agricultural pressures in the rapidly urbanizing rockland hammock areas in south Florida have resulted in significant reductions of this habitat type, which is also susceptible to fire, frost, canopy disruption, and groundwater reduction (FNAI 2010, pp. 24-26).

Extensive land clearing for human population growth and development in Miami-Dade County has altered, degraded, or destroyed hundreds of acres of this once abundant rockland hammock ecosystem. Rockland hammocks once occurred across the Miami-Rock Ridge, usually in association with pine rocklands, or the edges of marl prairies (areas of thin, calcitic soil that has accumulated over limestone bedrock) or tidal swamps (Service 1999, p. 122). Destruction of rocklands, including rockland hammocks, has occurred since the beginning of the 1900s. Historical impacts to the environment were addressed by Small (1938, p. 50), who called attention to the demise of
Trichomanes punctatum
ssp.
floridanum
from habitat destruction, and Phillips (1940, p. 167) who expressed his concern for south Florida hammocks due to the obvious and vast amount of destruction of land in the region. Early settlers in Florida cleared hammocks for residential development, farming, and range for livestock, while industrial logging also occurred in the region (Snyder
et al.
1990, pp. 271-272). Consistent burning of pinelands in Miami-Dade also encroached upon adjacent hammocks, as in the case of Castellow Hammock (Phillips 1940, p. 167). Habitat impacts were further exacerbated by natural stochastic events, such as the hurricane in 1935 that impacted Ross Hammock (Phillips 1940, p. 167).

Public conservation lands play a significant role in the recovery of rockland hammock habitat where future development and habitat alteration are less likely than on private lands. However, these lands could be sold off in the future and become more likely to be developed or altered in a way that negatively impacts the subspecies and its habitat. Additionally, rockland hammock may be found on private lands; however, the fate of this existing habitat is unknown, as it is dependent upon actions of individual property owners (see discussion under
Factor D
). Therefore, we find that habitat loss due to population growth, development, and agricultural conversion poses a threat to this subspecies in Miami-Dade County.

Sumter County
—In Sumter County, human population growth and development has occurred, but to a lesser degree than in Miami-Dade County. However, Sumter County has a long history of agriculture dating back to the early 1860s. Generally speaking, all land that was feasible for agriculture was cleared at some point. In particular, mesic hammocks where
Trichomanes punctatum
ssp.
floridanum
occurs have experienced disturbances from human activities such as logging, understory clearing, cattle grazing, and introduction of feral hogs. These natural mesic canopies and soils have largely been destroyed due to their desirable locations for living, camping, and recreating. The global and State rank for mesic hammock habitat (G3/S3) signifies it is considered to have a restricted range or be vulnerable to extinction from other factors (FNAI 2010, p. 22).

Concerns exist regarding future population growth and development in those communities remaining in Sumter County and on lands where urbanization and agriculture have not yet been established. According to the Sumter County Comprehensive Plan, a growth management paradigm has been developed that focuses public resources on urban areas to protect existing undeveloped land for agricultural use (Sumter County 2012, Data and Analysis section). Currently, the threat with greatest impact to
T.p.
ssp.
floridanum
habitat in Sumter County is the potential for agricultural and residential clearing of mesic hammocks on small, fragmented private parcels.

Privately owned land in the area around Wahoo where
Trichomanes punctatum
ssp.
floridanum
is found has been zoned as “agricultural” on the Sumter County Future Land Use Map (Sumter County 2012, p. 42). The County exempts single-site residential development and agriculture from environmental review and does not regulate land clearing for a single residence. Therefore, any undocumented populations and suitable habitat on private lands are at risk due to land-clearing activities, agricultural conversions, and development. For example, one Sumter County subpopulation observed in 1999 on private land was extirpated due to pasture clearing on the property for livestock (van der Heiden 2013c, pers. comm.). A full survey for
T.p.
ssp.
floridanum
and associated suitable habitat is needed in Sumter County to determine the severity of potential habitat loss on this subspecies regionally, including the potential impact from future human population growth and development.

Due to existing agricultural and residential clearing of mesic hammocks and potential future clearing on private lands, habitat loss due to human population growth, development, and agricultural conversion poses a threat to
T.p.
ssp.
floridanum
in Sumter County.

Regional Drainage and Consumptive Use

Miami-Dade County
—Landscape-level drainage has been extensive in Miami-Dade County. In the early 1900s, drainage initiatives were undertaken to modify land for agriculture and development. Impacts resulted in a region-wide drop in the water table (Nauman 1986, p. 182; Lodge 2005, p. 222), disturbing rockland hammocks and their flora (Service 1999, pp. 3-138), including
Trichomanes punctatum
ssp.
floridanum.
Additional stress from regional drainage for canal construction has also contributed to the decline of this metapopulation (Nauman 1986, p. 182; see also “Historical Range/Distribution,”
Miami-Dade County
section, above). As a consequence of the pervasive drainage throughout Miami-Dade County, solution holes, which often contained standing water during the rainy season, now hold much less, if any, water during much of the year, resulting in decreased ambient humidity levels (Phillips 1940, p. 171; Nauman 1986, p. 182; Adimey 2013a, field notes). Even though regional changes in hydrology have not caused extirpation of
T.p.
ssp.
floridanum
at most locations, they may have already induced stress by promoting vulnerability to other stressors, such as periodic long-term droughts, cold

weather exposure, and other stochastic events. Furthermore, groundwater levels in the vicinity of
T.p
ssp.
floridanum
are not targeted as part of the Comprehensive Everglades Restoration Plan (CERP) (a framework and guide to restore, protect, and preserve the water resources of central and southern Florida, including the Everglades), and, therefore, impacts from regional drainage are not expected to be ameliorated by CERP. Rockland hammocks in Miami-Dade County have been modified as a result of hydrology changes, reducing the amount of water available to these habitats. This is an ongoing threat to
T.p.
ssp.
floridanum,
as hammocks on limestone substrates are dependent on the underlying water table to keep humidity levels high, especially in limestone sinkholes (Service 1999, pp. 3-127).

Currently, the human population in Miami-Dade County 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). Although water demands will continue to rise with population increases, the extent of future impacts on existing habitat and the metapopulation of
Trichomanes punctatum
ssp.
floridanum
in Miami-Dade County is unknown at this time.

Sumter County
—In Sumter County, water drawdowns have historically been minimal. Regional modeling conducted by SWFWMD indicates less than a 0.06-m (0.2-ft) current use of water in the Upper Floridan Aquifer (Deangelis 2014a, 2014c, pers. comm.). No surface water withdrawals are currently occurring in Sumter County; however, they are possible in the future. Minimum flows and levels (MFLs), which are water withdrawal standards to limit water use set by the regional water management districts, are already established for the Withlacoochee River portion of the Withlacoochee River watershed in Sumter County. Although increases in human population and development in Sumter County may increase water use, it is believed that changes due to drought conditions (
e.g.,
on the order of several feet) will have a far greater impact on the hydrology (Deangelis 2013a, pers. comm.).

Hydrology Changes

Hydrology is a key ecosystem property that affects distribution and viability of rare plants (Gann
et al.
2009, p. 6). Hydrology changes have extensively modified and, in some cases, destroyed habitat in south Florida. As a result of human population growth, development, agricultural conversion, and regional drainage, the hydrology of
Trichomanes punctatum
ssp.
floridanum
habitat has changed drastically and has contributed to the alteration in ambient humidity and temperature.

For a hygrophilous (living or growing in damp places) subspecies thought to be restricted to a consistently humid microhabitat (Krömer and Kessler 2006, p. 57), high humidity is a critical factor to its survival, so any habitat modification or destruction that changes ambient humidity levels poses a threat to this subspecies (Nauman 1986, p. 182). As noted above, drainage efforts implemented in south Florida have significantly reduced historical water table levels, altering ambient humidity in the area. It is speculated that this subspecies may be living in discrete areas where humidity may be at the threshold for
T.p.
ssp.
floridanum
to survive. Minor drops in ambient humidity may limit reproduction and can negatively impact overall health of existing metapopulations, as well as inhibit the growth of new plants, impacting long-term viability (van der Heiden, 2013c, pers. comm.; Possley 2013e, pers. comm.). Van der Heiden and Johnson (2014, p. 9) recently observed this in Sumter County, where small drops in ambient temperature and humidity resulted in observed declines in the health of some clusters of
T.p.
ssp.
floridanum
within the local population.

Canopy Changes

Canopy also is an important habitat feature for
Trichomanes punctatum
ssp.
floridanum,
and, in most cases, is the primary factor controlling surrounding temperature and humidity levels that are critical to the survival of this subspecies. The proper amount of high shade and low light is critical for the persistence of this subspecies. These features help to maintain humidity and prevent desiccation from excessive light exposure (van der Heiden 2013c, pers. comm.; Possley 2013e, pers. comm.; Adimey 2013a-b, field notes). Currently, in both metapopulations, dense canopy cover is a necessity; however, the amount of canopy density needed to ensure survival is not yet known. Changes to existing canopies can result from land clearing and conversion, natural stochastic events, competition with nonnative species, and nonnative species control (see discussion under
Factor E
).

Historically, as land was developed, natural features of the landscape changed, directly eliminating
Trichomanes punctatum
ssp.
floridanum
and also eliminating surrounding vegetation and habitat features essential to this subspecies. Field observations in Miami-Dade County have found clusters of
T.p.
ssp.
floridanum
desiccated when the immediate canopy above the ferns was destroyed or substantially reduced, allowing high amounts of light into the understory (Possley 2013g, pers. comm.); however, over the course of many months, these clusters eventually recovered.

The loss of canopy can result in plant desiccation via increased sun and wind exposure, increased ambient temperatures, changes in ambient humidity, and the proliferation of exotic species (see
Factor E
discussion, below). Destruction or changes in canopy of any existing populations could result in elimination of an entire population. Therefore, we find the loss of canopy through habitat loss and modification to be a threat to
T.p.
ssp.
floridanum.

Habitat Fragmentation

Habitat fragmentation limits dispersal and population size, and promotes vulnerability among existing populations. In Miami-Dade County, most remaining
Trichomanes punctatum
ssp.
floridanum
habitat (
i.e.,
Fuchs, Meissner, Castellow, Hattie Bauer hammocks) is surrounded by housing development and agricultural land, resulting in scattered and small natural areas. Regional drainage and hydrology changes may also have contributed to the fragmented habitat in Miami-Dade County. In Sumter County, the impacts of habitat fragmentation are not as severe, as conservation lands are on large, adjacent tracts. Future development in Sumter County could result in an increase in fragmented habitat and pose a threat for this northern metapopulation (van der Heiden 2013c, pers. comm.). However, data regarding the impacts and subsequent consequences from habitat fragmentation are incomplete for both metapopulations of
Trichomanes punctatum
ssp.
floridanum.
Information and understanding of dispersal mechanisms for this subspecies are also currently lacking. The best available data for other plant species regarding the impacts of habitat fragmentation suggest that habitat fragmentation is likely a stressor impacting this subspecies but does not indicate that it rises to the level of a threat.

Conservation Efforts To Reduce Habitat Destruction, Modification, or Curtailment of Its Range

Conservation efforts to reduce habitat destruction are generally focused on the conservation of land on which both metapopulations occur. All known

extant populations occur on State- or County-owned land that is currently protected from future development. In Miami-Dade County, extant occurrences of
Trichomanes punctatum
ssp.
floridanum
have been protected through acquisition within the County's EEL Program.

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 (acquisition) 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 2013b, pers. comm.). To date, the Miami-Dade County EEL Program has acquired a total of approximately 95 ha (236 ac) of tropical hardwood and rockland hammocks (Gil 2013b, pers. comm.). The EEL Program also manages approximately 639 ha (1,578 ac) of tropical hardwood and rockland hammocks known as EEL Preserves and owned by the Miami-Dade County PROS Department, including some of the largest remaining areas of tropical hardwood and rockland hammocks (
e.g.,
Matheson Hammock Park, Castellow Hammock Park, and Deering Estate Park and Preserves). The EEL Program may acquire lands that were once under an EEL Covenant (see description below). However, the existence of an EEL Covenant is not a requirement or precursor for acquisition of lands under the EEL Program.

EEL Covenant Program

In 1979, Miami-Dade County established the EEL Covenant Program to reduce taxes for private landowners who own natural forest communities (NFC), such as pine rocklands and rockland hammocks. Under the EEL Covenant Program, landowners agree not to develop their property and to manage it for a period of 10 years, with the option to renew for additional 10-year periods (Service 1999, pp. 3-177). The EEL Covenant Program currently protects approximately 119 rockland hammock properties, comprising approximately 315.65 ha (780 ac) of habitat (Joyner 2013b, pers. comm.).

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 21 rockland hammock 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 removal of nonnative, invasive plants. Although the EEL Covenant Program has the potential to provide valuable habitat for unknown or future populations of
Trichomanes punctatum
ssp.
floridanum,
the actual contribution of these designated conservation lands is largely determined by whether individual landowners follow prescribed EEL management plans and NFC regulations (see “Local” under
Factor D
below).

The County- and State-owned land areas that are protected by the EEL Program are critical to providing habitat for
Trichomanes punctatum
ssp.
floridanum,
as well as other native flora in Florida. Conservation efforts to prevent the future extirpation of
T. p.
ssp.
floridanum
and other fern species in Miami's EEL Preserves have been under way for many years. In Miami-Dade County, conservation lands are and have been monitored by Fairchild and IRC, in coordination with the EEL Program and the NAM Division of Miami-Dade County's PROS Department, to assess habitat status and determine any changes that may pose a threat to or alter the abundance of
T. p.
ssp.
floridanum
(Possley 2013k, pers. comm.; van der Heiden 2013f-h, pers. comm.). Impacts to habitat (
e.g.,
canopy) 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.

Other Efforts

To date, only one reintroduction of filmy ferns (no specific species was indicated) was attempted by F.C. Craighead in the early 1960s, in several hammocks within ENP within the Long Pine Key area. These efforts were unsuccessful, but no explanation was provided as to why they were unsuccessful (Gann 2013). Within-range reintroductions into unoccupied habitat have historically resulted in low success rates for plants (Maschinski
et al.
2011, p. 159). Future reintroduction efforts will likely be attempted by MSBG from
Trichomanes punctatum
ssp.
floridanum
plants grown in-vitro from CREW.

In Sumter County, monitoring and management in Withlacoochee State Forest is provided through the Florida Forest Service (Werner 2013e, pers. comm.). Habitat is assessed annually for canopy changes that may alter ambient humidity levels and for impacts from nonnative plant species and feral pigs. Additionally, surveys on SWFWMD property are conducted periodically to assess habitat and search for rare plant species in the area (Deangelis 2013b, pers. comm.).

Summary of Factor A

Past human actions have destroyed, modified, and curtailed the range and habitat available for
Trichomanes punctatum
ssp.
floridanum.
Human population growth and development, agricultural conversion, and regional drainage have modified, or in most cases, destroyed, habitat where
T. p.
ssp.
floridanum
once occurred, thereby limiting the subspecies' current range and abundance in Florida.

In Miami-Dade County, habitat modification and destruction have severely impacted rockland hammocks that were once abundant. The
Trichomanes punctatum
ssp.
floridanum
metapopulation in Miami-Dade County is currently composed of four known populations, all on County-managed conservation lands. Historically,
T. p.
ssp.
floridanum
was found in an additional nine hammocks in Miami-Dade County. Most of these populations have been extirpated, and the historical range of the southern metapopulation has been reduced by nearly 80 percent. However, the subspecies was observed in “Monkey Jungle” (historically referred to as Cox Hammock) in 1989, and no thorough surveys have been conducted there since then. Upon recent visitation to the site (Adimey 2013a, field notes), the habitat features appeared to be similar to other hammocks where
T. p.
ssp.
floridanum
is currently known to occur (large solution holes, high humidity, dense canopy, standing water). Thus, much of the habitat has been destroyed, and while those fragments suitable for the plant remain protected in Miami-Dade County, habitat loss and modification from future development or conversion on private and conservation lands in Miami-Dade County poses a threat. In addition, the areas where
T. p.
ssp.
floridanum
currently exists are still vulnerable to activities in the surrounding areas, including agricultural clearing and hydrologic alterations.

The Sumter County metapopulation of
Trichomanes punctatum
ssp.
floridanum
is composed of two known

populations, both on State-owned land in the Jumper Creek Tract of the WSF. In central Florida, the subspecies was historically found in as many as seven additional locations. All of these historical populations have since been extirpated, primarily due to land conversion and clearing (including for cattle grazing) and the impacts of local and regional drainage. Land clearing and hydrological alterations on private lands adjacent to the Jumper Creek Tract continue to be threats to
T. p.
ssp.
floridanum
populations and habitat.

The destruction and modification of habitat have resulted in changes in canopy, humidity, hydrology, and fragmentation that have contributed to the declines of this taxon. High humidity and dense canopy cover are critical for
Trichomanes punctatum
ssp.
floridanum'
s survival. Therefore, any habitat modification or destruction that changes ambient humidity levels or canopy cover poses a threat to this subspecies. Data regarding the impacts of habitat fragmentation are incomplete for both metapopulations of
T. p.
ssp.
floridanum
because information on dispersal mechanisms of this subspecies is currently lacking. Habitat fragmentation is likely a stressor impacting this subspecies, but the best available data do not indicate that it rises to the level of a threat.

Conservation efforts are currently providing some benefits to this subspecies but are not sufficient to ameliorate the habitat threats. Therefore, based on the best information available, we have determined that the threats to
Trichomanes punctatum
ssp.
floridanum
from habitat destruction, modification, or curtailment are occurring throughout the entire range of the 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 is occurring and, therefore, we find that overutilization is not a threat to
Trichomanes punctatum
ssp.
floridanum.

Factor C. Disease or Predation

No diseases or incidences of predation have been reported for
Trichomanes punctatum
ssp.
floridanum.
Therefore, the best available data do not indicate that disease or predation is a threat to the subspecies.

Factor D. The Inadequacy of Existing Regulatory Mechanisms

Under this factor, we examine whether threats to the subspecies 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 under the Act, 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 are inadequate to address the specific threats to the species. Regulatory mechanisms, if they exist, may reduce or eliminate the impacts from one or more identified threats. In this section, we review existing Federal, State, and local regulatory mechanisms designed to address threats to
Trichomanes punctatum
ssp.
floridanum
to determine whether they effectively reduce or remove threats to the subspecies.

Federal

The only known extant populations of
Trichomanes punctatum
ssp.
floridanum
occur on State- or County-owned properties, and development of most of these areas is not likely to require a Federal permit or other authorization.

Section 404 of the Clean Water Act (CWA; 33 U.S.C. 1251
et seq.
) establishes a Federal program for regulating the discharge of dredged or fill material into waters of the United States, including wetlands. Additionally, section 401 of the CWA forbids Federal agencies from issuing a permit or license for activities that may result in a discharge to waters of the United States until the State or Tribe where the discharge would originate has granted or waived certification. The State of Florida maintains regulatory programs providing a framework for issuance of section 401 certifications related to applications for section 404 permits. This legislation does not prohibit the discharge of these materials into wetlands; rather, it provides a regulatory framework that requires permits prior to such action being taken. The U.S. Army Corps of Engineers (Corps) reviews individual permits for potentially significant impacts; however, most discharges are considered to have minimal impacts and may be covered by a general permit that does not require individual review.

On June 29, 2015, the Environmental Protection Agency and Corps published a final rule (80 FR 37054), effective August 28, 2015, that revises the definition of “waters of the United States.” Specific guidance on implementation of this revised definition is currently lacking, but it appears that the revised definition is likely to include hydric hammocks in areas where
Trichomanes punctatum
ssp.
floridanum
occurs in Sumter County among waters of the United States. However, as noted above, section 404 of the CWA does not necessarily prevent degradation to such habitats from the discharge of dredge or fill material. It simply provides a regulatory program for permitting activities that would result in such a discharge. Further, discharges associated with normal farming, ranching, and forestry activities, such as plowing, cultivating, minor drainage, and harvesting for the production of food, fiber, and forest products are exempt from the requirement to obtain a permit.

State

FNAI considers the State status of
Trichomanes punctatum
ssp.
floridanum
to be S1, “critically imperiled in Florida because of extreme rarity (five or fewer occurrences or less than 1,000 individuals) or because of extreme vulnerability to extinction due to some natural or man-made factor” (FNAI, 2013; Element Tracking Summary). The IRC considers its status as “critically imperiled” (Gann
et al.
2002, pp. 552-554).

The Florida Department of Agriculture and Consumer Services has listed
Trichomanes punctatum
ssp.
floridanum
on the Regulated Plant Index (Index) as endangered under Chapter 5B-40, Florida Administrative Code (State of Florida 2013, Florida Statutes). 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 chapter 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. Further, section (10) of the statute provides for consultation similar to section 7 of the 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). However, this statute provides no substantive protection of habitat or protection of potentially suitable habitat at this time. Sections (8)(a) and (b) of the statute waive State regulation for certain classes of activities for all species on the 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.

The Florida Forest Service (FFS) is the lead managing agency for State forests, as outlined in the Management Lease from the landowner (Board of Trustees of the Internal Improvement Trust Fund of the State of Florida) with guidance provided in chapters 253, 259, and 589 of the Florida Statutes (State of Florida, 2013 Florida Statutes, Preservation of Native Flora and Fauna). FFS is responsible for the management and supervision of the multiple-use guidelines of Withlacoochee State Forest. For research on State forest lands, prior approval is required. Research deemed legitimate will be issued a State Forest Use Permit (FDACS-11228) or letter of authorization (The Florida Forest Service 2013, State Forest Handbook).

Although the MFLs established by the South Florida Water Management District (SFWMD) in southeast Florida (a separate entity from the SWFWMD described earlier) are not directly applicable in the area of Miami Rock Ridge where
Trichomanes punctatum
ssp.
floridanum
occurs, they do indirectly limit ground water withdrawals in other areas of south Florida, including other areas of the Miami Rock Ridge. Unfortunately, MFL thresholds in place that establish water withdrawal standards are set so low that protection measures are rarely triggered. These low water level standards may be further exacerbated during times of drought, resulting in even greater impacts to the water table and the overall regional hydrology. Furthermore, MFL standards also do not apply to wells on private property or for consumptive use. The lowering of ground water and associated changes in local ambient humidity have already occurred throughout south Florida and have likely contributed to the decline of
T. p.
ssp.
floridanum
and possibly limited distribution and resilience (
i.e.,
ability to withstand stochastic (random) events and recover from disturbances) of the subspecies (Grossenbacher 2013, pers. comm.). Plants are likely to be further stressed by the continued lowering of ground water if additional large wells are created on private property for such activities as agriculture or during extended periods of drought because these types of circumstances are not regulated by the water withdrawal standards established by the SFWMD. In general, this regulatory mechanism has not been sufficient to reduce or remove the threat to
T. p.
ssp.
floridanum
posed by changes in hydrology discussed under
Factor A
by ensuring that current water levels will persist into the future.

Sumter County MFLs identified and adopted by the SWFWMD protect the Withlacoochee River and the Tsala Apopka lake chain, which connects to the Withlacoochee in the vicinity of Jumper Creek Tract where
Trichomanes punctatum
ssp.
floridanum
occurs. Maintaining designated MFLs will have a direct bearing on the design of future water supply development projects, of which there are several already proposed in Sumter County (Deangelis 2014c, pers. comm.). However, it is uncertain how these future projects would impact extant occurrences of
T. p.
ssp.
floridanum
or suitable habitat for the subspecies.

Local

In 1984, section 24-49 of the Code of Miami-Dade County established regulation of County-designated NFCs. 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 (RER) has regulatory authority over these County-designated NFCs and is charged with enforcing regulations that provide partial protection of remaining upland forested areas designated as NFC on the Miami Rock Ridge. NFC regulations are designed to prevent clearing or destruction of native vegetation within preserved areas. Miami-Dade County Code typically allows up to 10 percent of a rockland hammock designated as NFC to be developed for properties greater than 5 acres and requires that the remaining 90 percent be placed under a perpetual covenant for preservation purposes (Joyner 2013a, 2014, pers. comm; Lima 2014, pers. comm.). However, for properties less than 5 acres, up to one-half an acre can be cleared if the request is deemed a reasonable use of property; this allowance often can be greater than 10 percent of the property (Lima, 2014, pers. comm.). 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. When discovered, unpermitted work is pursued by RER through appropriate enforcement action, and restoration is sought when possible. The NFC program is responsible for ensuring that NFC permits are issued in accordance with the limitations and requirements of the county code and that appropriate NFC preserves are established and maintained in conjunction with the issuance of an NFC permit when development occurs.

Although the NFC program is designed to protect rare and important upland (non-wetlands) habitats in south Florida, it is a regulatory strategy with limitations. For example, in certain circumstances where landowners can demonstrate that limiting development to 10 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 in limited circumstances for parcels less than 2.02 ha (5 ac) in size and requires coordination with the landowners only if they plan to develop property or perform work within the NFC designated area. As such, many of the existing private forested NFC parcels remain fragmented, 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 the Miami-Dade County Code (Grossenbacher 2013, pers. comm.).

Although
Trichomanes punctatum
ssp.
floridanum
is currently afforded some protection from outright destruction on public conservation land, changes in the surrounding landscape that affect the subspecies are not regulated. For example, the private property known as “Monkey Jungle” (historically referred to as Cox Hammock) is a public attraction and is home to a considerable number of primate species. Upon recent visitation to this site (Adimey 2013a, field notes), the habitat features appeared to be similar to other hammocks where
T. p.
ssp.
floridanum
currently is known to live (
i.e.,
large solution holes, high humidity, dense canopy, standing water). Although much of the hammock has been altered to accommodate captive animals and visitors, a significant portion of the hammock still remains untouched and overgrown with extensive nonnative, invasive plant species. “Monkey Jungle” receives limited protection under the Miami-Dade County Environmental Protection Ordinance as an NFC, where only portions of NFCs can be cleared once a permit is obtained from the County.

Additionally, Miami-Dade County has oversight of any work or research completed within the local preserve areas; permits are required for any outside work or research on County-owned lands in order to further protect the habitat from potential direct or indirect impacts (Gil 2013a, pers. comm.).

Under section 13-644(a)(1) of the Sumter County code, “[m]ajor developments shall identify and protect habitats of protected wildlife and vegetation species,” and in section 13-644(a)(1)2.b.2, “[n]o permit will be issued for development which results in unmitigated destruction of specimens of endangered, threatened or rare species.” Therefore, the County code prevents unmitigated destruction of endangered, threatened, or rare species only when associated with “major developments.” Current zoning in the Wahoo area limits development to one unit per 4 ha (10 ac); therefore, “major developments” do not seem to be likely in that area. In general, existing county ordinances do not prevent the conversion of habitat to agricultural use or building on sites with endangered, threatened, or rare plant species. Without complete survey information for Sumter County, it is difficult to assess the extent to which unknown occurrences and suitable habitat on private lands are at risk. Agriculture and development are ongoing and promoted in this County, and no regulatory mechanisms exist that protect
T. p.
ssp.
floridanum
and its habitat on private lands.

Summary of Factor D

Currently,
Trichomanes punctatum
ssp.
floridanum
is only known to occur on State and County lands; however, there are no regulatory mechanisms in place that provide substantive protection of habitat or protection of potentially suitable habitat at this time. In addition, subsections of applicable statutes waive State regulation for private landowners or their agents, allowing certain activities to clear or remove species on the Index. Little, if any, protection is afforded to
T. p.
ssp.
floridanum
by the established MFLs in south Florida, as they are set very low, are rarely triggered, and are not applicable in the portion of the Miami Rock Ridge where the subspecies currently lives. Established MFLs in Sumter County can positively impact areas where
T. p.
ssp.
floridanum
occurs, provided that these designated MFLs are maintained when future water supply development projects are undertaken. The NFC program in Miami is designed to protect rare and important upland (non-wetland) habitats in south Florida. However, this regulatory strategy has several limitations that can negatively affect
T. p.
ssp.
floridanum.
Sumter County code prevents unmitigated destruction of endangered, threatened, or rare species only when associated with “major developments” and does not prevent conversion of habitat to agricultural use or building on private property.

Although all known extant populations of
Trichomanes punctatum
ssp.
floridanum
are afforded some level of protection because they are on public conservation lands, existing regulatory mechanisms have not led to a reduction or removal of threats posed to the subspecies 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
Trichomanes punctatum
ssp.
floridanum
to varying degrees. Specific threats include the spread of nonnative, invasive species; potentially incompatible management practices (
e.g.,
inadvertent spraying of
T. p.
ssp.
floridanum
while controlling for nonnatives); 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). Each of these threats and its specific effect on
T. p.
ssp.
floridanum
is discussed in detail below.

Nonnative Species

Nonnative species can stress, alter, or even destroy native species and their habitats. The threat of nonnative plant species is ongoing due to their: (1) Number and extent, (2) ability to out-compete native species, (3) abundant seed sources, and (4) extensive disturbance within habitats. Further challenges exist due to limitation of resources to combat this threat, as well as the difficulty in managing fragmented hammocks bordered by urban development, which often can serve as seed sources for nonnative species (Bradley and Gann 1999, p. 13). Nonnative, invasive plants compete with native plants for space, light, water, and nutrients, and they limit growth and abundance of natural vegetation and can make habitat conditions unsuitable for native plants.

In south Florida, at least 162 nonnative plant species are known to invade rockland hammocks. Impacts are particularly severe on the Miami Rock Ridge (Service 1999, pp. 3-135). Nonnative plant species have significantly affected rockland hammock and mesic hammock habitats where
Trichomanes punctatum
ssp.
floridanum
occurs and are considered one of the threats with greatest impact to the subspecies (Snyder
et al.
1990, p. 273; Gann
et al.
2002, pp. 552-554; FNAI 2010, pp. 22, 26). Nonnative plants outcompete and displace
T. p.
ssp.
floridanum
in solution holes, and may form dense strata (layers) in the hammock, where it is possible that the fern may be blanketed and smothered (Possley 2014c, pers. comm.). It has also been suggested that the insular nature of south Florida, as well as the hammocks themselves, predispose this habitat to

invasion by nonnative plants (
e.g.,
the proximity of seed sources, which increases the volume of nonnatives and accelerates the time it takes for the arrival and establishment of nonnatives) (Horvitz
et al.
1998, p. 961).

In many Miami-Dade County parks, nonnative plant species comprise 50 percent of the flora in hammock fragments (Service 1999, pp. 3-135). Horvitz (
et al.
1998, p. 968) suggests the displacement of native species by nonnative species in conservation and preserve areas is a complex problem with serious impacts to biodiversity conservation. Problematic nonnative invasive plants in Miami-Dade County associated with
Trichomanes punctatum
ssp.
floridanum
include
Schinus terebinthifolia
(Brazilian pepper),
Bischofia javanica
(bishop wood),
Syngonium podophyllum
(American evergreen),
Jasminum fluminense
(Brazilian jasmine),
Rubus niveus
(mysore raspberry),
Thelypteris opulenta
(jeweled maiden fern),
Nephrolepis multiflora
(Asian swordfern),
Schefflera actinophylla
(octopus tree),
Jasminum dichotomum
(Gold Coast jasmine),
Epipremnum pinnatum
(centipede tongavine), and
Nephrolepis cordifolia
(narrow swordfern) (Possley 2013g-h, pers. comm.).

In Sumter County, the most problematic nonnative invasive species occurring in
Trichomanes punctatum
ssp.
floridanum
habitat are
Tradescantia fluminensis
(small leaf spiderwort) and
Paederia foetida
(skunkvine) (Werner 2013d, pers. comm.). Furthermore,
Citrus aurantium
(bitter orange) is found in this locale and is considered problematic due to its tendency to attract feral hogs, another nonnative species associated with extensive habitat destruction (see below). Agricultural fields in proximity to the Sumter metapopulation are a nonnative seed source, increasing potential encroachment of nonnative plants to the area (Werner 2013b-c, pers. comm.).

In some instances, management of nonnative vegetation may also be detrimental, in that nonnative species may actually provide the necessary canopy to limit sunlight exposure and control humidity, so that removing the nonnative species exposes the fern. In Castellow Hammock, the majority of the shade near two of the large solution holes containing
Trichomanes punctatum
ssp.
floridanum
is provided by giant
Schinus terebinthifolia
trees; eliminating these trees could likely result in detrimental effects to
T. p.
ssp.
floridanum
residing in the underlying solution holes. In hammocks such as Castellow, desiccation from excessive sun exposure due to the removal of
S. terebinthifolia
canopy has already occurred. In this case, the subpopulation of
T. p.
ssp.
floridanum
below the
S. terebinthifolia
tree turned brown; however,
T. p.
ssp.
floridanum
could eventually revitalize if sufficient canopy is reestablished to limit sunlight exposure (Possley 2013d, pers. comm.). Additionally, nonnative plant control may also become a threat when
T. p.
ssp.
floridanum
is inadvertently sprayed while authorities conduct local nonnative removal efforts (Possley 2013d, pers. comm.).

Nonnative plant species are also a concern on private lands, where often these species are not controlled due to associated costs, lack of interest, or lack of knowledge of detrimental impacts to the ecosystem. Overall, active management is necessary to control for nonnative species and to protect unique and rare habitat where
T.p.
ssp.
floridanum
occurs (Snyder
et al.
1990, p. 273). Treatment of nonnative plant species should consider canopy and humidity needs of
T.p.
ssp.
floridanum.

Nonnative feral hogs living in the Withlacoochee State Forest are also considered a threat to this plant. Surveys in Sumter County have revealed evidence of hogs lying against or rubbing their bodies against large rocks, removing existing vegetation in the process. Recently, van der Heiden and Johnson (2014, p. 11) found one small rock where
Trichomanes punctatum
ssp.
floridanum
had been scraped off when a hog rubbed itself on the rock after wallowing in the mud. Furthermore, rooting from hogs can destroy existing habitat by displacing smaller rocks where
T.p.
ssp.
floridanum
is found to grow and potentially damaging or eliminating a cluster (Werner 2013d, pers. comm.). In Withlacoochee State Forest, damaged areas from feral hogs are also more susceptible to invasion from nonnative plant species, such as
Urena lobata
(Caesarweed) and
Tradescantia fluminensis
(small-leaf spiderwort) (Werner 2013a, pers. comm.). If feral hogs continue to forage in areas where
T.p.
ssp.
floridanum
lives, it is possible that entire clusters inhabiting one rock/boulder could be eliminated.

In recent years, scientists in south Florida have noticed an increase in sightings of the nonnative genus
Zachrysia
(Cuban tree snails). Although snail grazing has not been observed on
Trichomanes punctatum
ssp.
floridanum,
it has been documented on other rare ferns living in the same habitat and could possibly become a threat in the future, either by this snail or another introduced species (Possley 2013b, c, pers. comm.).

Climate Change

Climatic changes, including sea level rise (SLR), are occurring in the State of Florida and are impacting associated plants, animals, and habitats. The term “climate,” as defined by the Intergovernmental Panel on Climate Change (IPCC), refers to the mean and variability of different types of weather conditions over time, with 30 years being a typical period for such measurements, although shorter or longer periods also may be used (IPCC 2013, p. 1450). The term “climate change,” thus, refers to a change in the mean or variability of one or more measures of climate (
e.g.,
temperature or precipitation) that persists for an extended period, typically decades or longer, whether the change is due to natural variability, human activity, or both (IPCC 2013, p. 1450). A recent compilation of climate change and its effects is available from reports of the IPCC (IPCC 2013, entire).

Various changes in climate may have direct or indirect effects on species. These effects may be positive, neutral, or negative,

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Source: Frix Law Library, https://www.frixlaw.com/law-library/documents/fr%3A2015-25299. Public record. Not legal advice.