Diversity and Rareness: Ferns as a Measure of Diversity
The remnants of the Arcto-Tertiary forest,
both here and in China, have made for two of the most diverse temperate
regions of the world. Within our local remnant, the Clinch River
watershed stands out as a “biodiversity hotspot”, meaning that the
watershed contains more types of plants and animals than can be found
anywhere else in the continental U.S. These waters flowing past
Sugar Hill contain more mussel species than can be found in all of
Europe and China combined. Scientists also marvel over the
varying colors and species of millipedes, the diversity of snail life,
and the stunning variety of plants in our
area. On Sugar Hill itself, a survey of just the herbaceous
understory plants (the small plants on the forest floor) turned up 155
species.
Where does one
start when exploring this astonishing diversity? As a youngster
beginning to learn about the Appalachian forest, I was lucky enough to
spend a few days following in the footsteps of the noted local
naturalist Arthur Smith. Only years later did I discover how well
known Arthur was in the region --- at the time, I was tempted out in
the field by the extra chocolate bar he liked to bring along to share
as part of our lunch. In addition to feeding my sweet tooth, he
simplified the world in a way that made sense, showing me how to gauge
an area’s overall diversity by keeping an eye on the ferns.
Arthur explained that places with a large number of different fern
species tend to have a higher diversity of other kinds of life --- more
wildflowers, more salamanders, more trees.
First he taught
me to watch out for our most common ferns --- Christmas Fern with its
simple leaflets shaped like stockings and Ebony Spleenwort with its
shiny black stem. On moist, shady hillsides, the divided fronds
of Maidenhair Ferns are likely to arch delicately over the leaf
litter. Rattlesnake Fern is considered an indicator species for
Ginseng and can be found in the moist coves
where that species once grew before overcollection nearly wiped it off
the map. Drier, more open woods are often home to Hay-scented
Ferns, so named for the grassy odor that wafts up from their lacy
fronds when brushed by a passing pant leg.
Other ferns are
less widespread, each with its own microhabitat. On Sugar Hill,
the limestone cliffs
house Walking Fern, named for its habit of rooting a new fern at the
end of its attenuated, arrowhead-shaped frond. Bulblet Bladder
Fern also thrives on limestone where it reproduces by dropping little
bulblets from the underside of its fronds. Each bulblet will
sprout tiny new leaves and grow into a daughter fern. Meanwhile,
drier limestone cliffs on the western side of the hill are home to
Purple-stemmed Cliff-Brake, an unusual fern with asymmetrical fronds,
and Wall-Rue. Finally, Goldie’s Wood Fern and Narrow-leaved Glade
Fern thrive in habitats similar to those enjoyed by Maidenhair and
Rattlesnake Ferns.
Eleven fern
species have been found so far at Sugar Hill, a large number for a
preserve so small. Just as you can measure an area’s overall
diversity by counting its fern species, you can also get an idea for
what drives that diversity. Varying habitats abound on Sugar
Hill, each with its own array of plants and animals. Ancient heritage and a
varied terrain are two of the factors that make Sugar Hill a treasure
trove of Appalachian nature.
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Ferns Not Pictured
Maidenhair
Fern
Scientific
Name: Adiantum pedatum
Family:
Pteridaceae (Maidenhair Fern Family)
Habitat:
Moist, shady places
Purple-stemmed
Cliff-Brake
Scientific
Name: Pellaea atropurpurea
Family:
Pteridaceae (Maidenhair Fern Family)
Habitat:
Dry limestone rocks
Ebony
Spleenwort
Scientific
Name: Asplenium platyneuron
Family:
Aspleniaceae (Spleenwort Family)
Habitat:
Woods and rocks
Walking
Fern
Scientific
Name: Asplenium rhizophyllum
Family:
Aspleniaceae (Spleenwort Family)
Habitat:
Shaded rocks, usually on limestone
Bulblet
Bladder Fern
Scientific
Name: Cystopteris bulbifera
Family:
Dryopteridaceae (Wood Fern Family)
Habitat:
Shaded limestone rocks
Narrow-leaved
Glade Fern
Scientific
Name: Diplazium pycnocarpon
Family:
Dryopteridaceae (Wood Fern Family)
Habitat:
Moist, shady places
Goldie’s
Wood Fern
Scientific
Name: Dryopteris goldiana
Family:
Dryopteridaceae (Wood Fern Family)
Habitat:
Rich woods, most often on acidic soil
Hay-scented
Fern
Scientific
name: Dennstaedtia punctilobula
Family:
Dennstaedtiaceae (Bracken Family)
Habitat:
Open fields and woodland edges
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