Experimental Reintroduction of American Hart’s-Tongue Fern
(Asplenium scolopendrium var. americanum): Effects of
Transplant Type on the Establishment of New Populations
Michael Serviss
SUNY College of Environmental Science and Forestry
Final Report to the Edna Bailey Sussman Foundation, 2015
Background
Asplenium scolopendrium var. americanum (American Hart’s-tongue fern,
AHTF) is listed as threatened under the U.S. Endangered Species Act of 1973. The
most recent review of the fern’s status in the United States by the USFWS
indicates that the fern has one extant population each in Alabama and
Tennessee, eleven in Michigan and fifteen in New York (USFWS, 2012). Some
populations in New York and Michigan are considered self-sustaining, i.e. they
contain reproducing individuals and are large enough in size (total individuals)
to maintain sufficient genetic variation to be able to survive naturally variable
conditions within their habitat (USFWS, 1993; USFWS 2012). While the report
indicates that some AHTF populations in New York (the focus region of this
internship) are considered self-sustaining, it concludes that conservation goals as
they relate to sustainable populations have not yet been met.
Reintroduction of AHTF has been proposed by the USFWS, as well as
current and previous AHTF researchers, as a means of recovering the species
within its native range (USFWS, 1993). While plant reintroductions have been
documented with varying success throughout the world, very few instances of
the reintroduction of a threatened or endangered fern or other spore-bearing
plant have been documented (see Becker and Becker, 2010; Aguraiuja, 2011;
Chau and Reyes, 2014). Furthermore, research in plant reintroduction has
focused little attention on the significance of transplant life stage at the time of
reintroduction. This is especially important in the reintroduction of AHTF as it has
been suggested that the sporeling stage of the life cycle of AHTF may be
particularly susceptible to desiccation due to very specific microclimate
requirements and the periodicity of sporeling development within the generally
drier summer months (Fernando et al., 2015). It has been suggested that an
earlier life stage of AHTF, the gametophyte (Figure 1), is tolerant to desiccation
(Testo and Watkins, 2013). Aguraiuja (2011) proposed that use of the
gametophyte as a reintroduction transplant should be considered, but prior to
its use during this internship it had yet to be attempted. The objective of this
research is to determine which life stage is the most suitable for use as a
transplant in the event of future reintroduction efforts.
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Figure 1. AHTF gametophytes grown from spore in a petri dish at SUNY-ESF, Syracuse, NY.
At maturity, they are about the size of a pinky finger nail and contain the structures
necessary for reproduction. Photo: Michael Serviss.
In addition to reintroduction, invasive species management in and
around the populations of AHTF is a critical component to meeting conservation
targets. The invasive species of main concern is Cynanchum rossicum (Pale
swallow-wort) (Figure 2). Pale swallow-wort has been the focus of invasive
species control around the area of AHTF populations for several years and will
continue to be for many more years. Other invasive species of concern to AHTF
include Lonicera japonica (Japanese honeysuckle), Alliaria petiolata (Garlic
mustard) and Rhamnus cathartica (Common buckthorn).
Figure 2. An area overgrown with Pale swallow-wort in Clark Reservation State Park,
Jamesville, NY. August 2015. Photo: Michael Serviss.
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Overview of Proposed Research
Under the supervision of Thomas Hughes, Natural Resource Steward
Biologist for the Central and Finger Lakes Regions of NYS Parks, I planned to lead
a team of seasonal employees and volunteers in the experimental
reintroduction of AHTF at three sites in central New York. Two of the sites, Sentinel
Basin and Twin Basins, are located at Clark Reservation State Park in Jamesville,
NY while the other site, Split Rock Unique Area, is a NYS DEC property located in
the town of Onondaga, NY. I also intended to lead this team in invasive species
management efforts and environmental education projects at Clark
Reservation and Chittenango Falls State Parks.
Narrative of Completed Work
The team and I, affectionately referred to as “The Fern Crew” by NYS Parks
employees, planted over 1800 total AHTF transplants that were grown at SUNYESF between the three aforementioned sites in Clark Reservation State Park and
Split Rock Unique Area. The three reintroduction sites were chosen by a
combination of GIS analysis of suitable habitat, expert opinion from AHTF
researchers and field investigation of each site to determine suitability.
Nine plots were delineated at each site for organizational purposes and
each plant was tagged with a unique ID number on a plastic marker (Figure 3).
The transplants were organized by life stage and lineage (genotype) and
disseminated as evenly as possibly between not only the sites, but also the plots
within each site.
Four life stages (transplant types) are of interest to this project, including
spores, gametophytes, sporelings (1-2 year old ferns) and immature sporophytes
(2-5 year old ferns that are not yet reproducing). Data concerning the survival of
each transplant type was collected in October 2015. Of 127 spore plates (petri
dishes containing potting soil and AHTF spores) planted across each site, no
germination of spores was observed during data collection. The gametophyte
life stage, despite their observed potential to withstand desiccation, exhibited
the lowest survival percentage of all transplant types at each site. Although,
some of the 1305 gametophyte transplants did produce sporelings between July
and October, indicating that at least a few were reproductively active during
this time. The sporeling life stage exhibited much greater survival than the
gametophyte life stage across all sites. A total of 275 sporelings were planted.
Lastly, the more developed immature sporophyte life stage exhibited the
greatest survival percentage across all sites. A total of 230 immature sporophytes
were planted. Based on these preliminary results, it would appear that the more
advanced life stages have the best potential for use in reintroduction efforts of
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AHTF. Although, as AHTF is a perennial fern, these results may drastically change
after the transplants experience their first winter season.
A
B
C
Figure 3. Three of the four life stages of AHTF used as transplants. A. Transplanted AHTF
gametophytes. B. Transplanted AHTF sporelings. C. A transplanted AHTF immature
sporophyte. Taken October 18, 2015. Photos: Michael Serviss.
In addition to the ferns, 3 microclimate monitoring stations were installed
at each site (Figure 4). The stations were generously provided by NYS Parks to
aid in this research, as well as future conservation efforts relating to AHTF. Each
station was programmed to measure temperature, relative humidity, wind
speed and wind direction at 15 minute intervals for the duration of the project.
These data are yet to be analyzed, but will provide insight into the general
microclimatic conditions at each site as well as any differences that may exist
between each reintroduction site.
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Figure 4. Fern Crew member Haixu Zhao poses with a microclimate monitoring station at
the Sentinel Basin site, Clark Reservation, in July 2015. Photo: Michael Serviss.
Another significant task during the course of the internship was invasive
species removal. Our main focus was on Pale swallow-wort throughout Clark
Reservation and Chittenango Falls State Parks. The Fern Crew removed over
10,000 individual plants from areas within and around AHTF habitat. Each of
these plants was removed by hand using trowels and other digging tools. Where
mechanical removal was not possible, clipping of Pale swallow-wort seed pods
(Figure 5) was performed, resulting in the removal of over 30 large garbage
bags of seed pods as a preventative measure. Additionally, the crew worked
closely with a certified herbicide applicator to identify and implement the
removal of Pale swallow-wort from priority areas. Garlic Mustard was also a
target plant of the crew, although its abundance is much less prevalent than
Pale swallow-wort. Over the course of the internship, over 2000 individual Garlic
Mustard plants were removed from areas in and around AHTF habitat.
Figure 5. Pale swallow-wort seed pods were removed as a preventative measure where
mechanical removal of the plant was not feasible. Photo taken at Clark Reservation
State Park, August 2015. Photo: Michael Serviss.
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Lastly, I lead numerous guided hikes and educational programs for
summer youth groups at Clark Reservation. The purpose of these programs was
to expose generally inner-city youth to the diversity of flora and fauna within the
park. They were lead through the park to see everything from snakes, birds,
aquatic invertebrates and, of course, AHTF. The importance of conservation of
endangered species was highlighted as well as ways in which to manage
threats from invasive species. Hands-on participation was encouraged and a
number of memorable educational experiences were created (Figure 6).
Figure 6. Camp Green Teen learns about ferns during a guided hike at Clark
Reservation on August 3, 2015. Photo: Thomas Hughes.
Future Directions
The experience I have gained through this internship will significantly help
my thesis research. I have developed and honed an understanding of field
techniques and management skills that will prove invaluable as I continue my
research into a second field season and beyond.
While the information presented in this report focuses on survival of
transplants by life stage, additional analyses will include growth, changes in
health, effects of genotype (if any) and analysis of microclimatic conditions at
each site. Other site characteristics will also be explored, including soil pH, soil
moisture and canopy cover.
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Insights and recommendations created this summer in regards to invasive
species removal will also be utilized in future efforts to manage the spread of
invasive species within Clark Reservation. This is an ongoing and critical
component to the conservation of the American Hart’s-tongue Fern.
Acknowledgements
I would like to thank NYS Parks, especially Tom Hughes and the Fern Crew,
of which there are too many names to list. Thanks to my advising committee at
SUNY-ESF, Danny Fernando, Don Leopold and Robin Kimmerer for all of their
expert insight. A special thanks to my field assistants from SUNY-ESF, Kelsey West
and Olivia Morris. Many thanks to the organizations that have been involved in
the AHTF conservation project over the years, including the NY Natural Heritage
Program, USFWS and NYS DEC and all who have supported the project. Lastly, I
would like to thank the Edna Bailey Sussman Foundation for making this research
possible.
Literature Cited
Aguraiuja, R. (2011). Reintroduction of the endangered fern species Woodsia ilvensis to Estonia:
A long-term pilot study. Biodiversity and Conservation, 20, 391-400.
Becker, T., & Becker, U. (2010). Successful transplantation of a hart’s tongue fern population
(Asplenium scolopendrium L.) with ten years of monitoring. Tuexenia, 30, 47-58.
Chau, M., & Reyes, W. (2014). Effects of Light, Flooding, and Weeding on Experimental
Restoration of an Endangered Hawaiian Fern. Restoration Ecology, 22(1), 107-116.
Fernando, D. D., Discenza, J. J., Bouchard, J. R., & Leopold, D. J. (2015). Genetic analysis of the
threatened American hart's-tongue fern (Asplenium scolopendrium var. americanum
[Fernald] Kartesz and Gandhi): Insights into its mating system and implications for
conservation. Biochemical Systematics and Ecology, 62, 25-35.
Testo, W.L. and J.E. Watkins, Jr. (2011). Comparative development and gametophyte
morphology of the hart's-tongue fern, Asplenium scolopendrium L. Journal of the Torrey
Botanical Society. 138: 400–408.
USFWS (United States Fish and Wildlife Service). 1993. Recovery Plan for American hart’s-tongue
(Asplenium scolopendrium L. var. americanum [Fernald] Kartesz and Gandhi [Synonym:
Phylitis scolopendrium (L.) Newman var. Americana Fernald]). U.S. Fish and Wildlife
Service Atlanta, GA.
USFWS (United States Fish and Wildlife Service). 2012. American Hart's-tongue Fern (Asplenium
scolopendrium var. americanum) 5 year review: summary and evaluation. U.S. Fish and
Wildlife Service Ecological Services Field Office Cookeville, TN. 23.
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