Greenbrier, GSMNP   Jess Riddle
  Feb 05, 2007 18:50 PST 


In trip reports and rankings of sites, the Smokies are often referred
to as a single distinct entity. However, that view reflects political
realities more than ecological realities, provides an uneven basis for
comparisons between sites, and overlooks the great variety of
different regions of the park. At 520,000 acres, the Smokies are far
lager than most areas ENTS refer to as "sites", and consequently has a
more heterogeneous disturbance history and geology than other sites.
In an attempt to alleviate some of those issues and provide a fuller
context for trip descriptions from the Smokies, I am planning to write
a serious of descriptions on distinct regions of the park, of which
this is the first. Of course, even within restricted regions,
conditions are not uniform, and the national park does include most of
a discrete mountain range with some consistent patterns of climate and
other factors. Still, to people familiar with the park, simply
knowing what section a stream is in can provide a great deal of
information about forest conditions within the watershed.

These descriptions derive from my observations on repeated hikes
through the areas rather than any systematic or formal samples of the
vegetation. Consequently, they may be biased by selective attention,
distortions of imperfect memory, or the sites I happen to have visited
being atypical. They also differ from the actual forests by focusing
on only the most common woody species from mixtures that are
frequently diverse, and by lumping varied communities in broad,
discrete categories. I encourage any other ents familiar with the
areas to correct or add to these descriptions.


Once a small farming community, Greenbrier now refers to the portion
of Great Smoky Mountains National Park drained by the Middle Prong
Little Pigeon River, which lies between Gatlinburg, TN and Cosby, TN.
Although a few streams flow out of the park before merging with the
Middle Prong, most of the watershed lies within a broadly forked
valley surrounded by steep, spruce-topped ridges. Those surrounding
ridges include not only the main divide of the Great Smoky mountain
range but also the prominent spurs of Greenbrier Pinnacle and The
Boulevard. Along the boarder with Greenbrier, the divide, which also
serves as the TN/NC state line, dips only as low as 5233' elevation,
and rises as high as 6621' on top of Mount Guyot, the second highest
peak in the Smokies. Three miles from the divide and at The
Boulevard's terminus, the Smokies third highest peak, Mount Le Conte
(6593'), overlooks the western side of Greenbrier. On the other side
of the valley, Greenbrier Pinnacle juts out five miles from the divide
before dropping below 4500' and reaching an abrupt end, the former
site of a fire tower.

Steep slopes descend from all of those major ridges into the valley,
especially along The Boulevard and the western end of the divide.
Anakeesta slate supports that stretch, and typically weathers into a
dramatic landscape of narrow ridges and precipitous slopes. That
topography combines with the thin soils and wet climate to make the
area prone to landslides, which have produced the large scars on the
landscape seen at Charlies Bunion and Eagle Rocks. The Thunderhead
Sandstone that underlies the mid-elevations and eastern parts of the
valley produces more rounded peaks and more stable, but still steep,

Those slopes channeled most historical human activity in the watershed
to the lower elevations. Extensive farming occurred on the gentle
terrain watered by many small streams at the foot of Greenbrier
Pinnacle and at the base of Mount Le Conte, areas now just inside the
northern boarder of the national park. Farming also occurred within
the main valley, but was primarily restricted to the flats along the
larger streams' lower ends. Adjacent to the farms and along low
elevation streams, commercial logging operations cleared the forests,
and sometimes ventured farther upstream for large tuliptrees and black
cherries. However, that disturbance pattern has left large sections
of the watershed completely untouched by logging operations. Most
modern human activity in the area focuses on either those least
disturbed sections or the historically most altered ones. The handful
of trails in Greenbrier, relatively few compared to some other areas
of the park, lead through old fields to stone walls, reconstructed
buildings, or cemeteries; or follow streams to waterfalls in forests
with many large trees.

The former fields now stand out from the surrounding forest by their
structural simplicity and lack of diversity. Arrow straight
tuliptrees have replaced straight rows of corn or potatoes. While
only scattered red maples, black locusts and near the larger streams
sweetgum, and sycamore compete with the tuliptrees in the overstory,
the understory displays a patchier structure with thickets of young
hemlocks, and striped maples in addition to more scattered flowering
dogwoods, and near streams hornbeam and umbrella magnolia. In some
areas, the naturalization of black walnut has supplemented that native
diversity, and spicebush often occupies the understory in those areas.

Settlers typically bypassed drier, less fertile, or steeper
surrounding slopes, but those areas were still cleared for timber.
The richest of them, typically steep and north facing, also support
tuliptree dominated canopies, but the tuliptrees are typically larger
than those in farmed areas and the understory includes saplings of
rich site species such as silverbell and yellow buckeye. On other
moist sites hemlock can dominate and permit either a sparse understory
or a dense rhododendron dominated understory. Drier slopes feature
more mixed canopies that usually include chestnut oak and red maple
over understories of mountain laurel.

Those same species also dominate the dry ridges in the unlogged
portions of the area. On the most exposed and driest ridges, the oaks
and maples yield canopy space to table mountain pine, and wintergreen
(Gaultheria procumbens) may form an evergreen ground cover. On
moister ridges that retain their original forest cover, eastern
hemlock becomes a major canopy constituent. On level or north facing
ridges, the cool, wet climate between 4000 and 4500' elevation allows
hemlock to exclude all other species from the overstory, but rosebay
rhododendron thrives in the understory. At slightly lower elevations,
north facing ridges and adjacent slopes with deep soils support
another hemlock dominated community that The Nature Conservancy lists
as globally rare. Those conditions allow silverbell, but few other
species, to compete effectively with the hemlocks. Since rhododendron
is limited in extant in the community, a fairly continuous and largely
evergreen herbaceous layer develops dominated by intermediate wood
fern, partridgeberry, Indian cucumber and occasionally Frasers sedge.
Curiously, hemlock does not appear as longed lived in this community,
and does not obtain as large of diameters as on the higher ridges.

Along the streams and lower slopes at mid elevations in the uncut
forest, hemlock is even more ubiquitous and becomes the most common
overstory species. The conifer shares space with red maple, black
birch, yellow birch, and tuliptrees over a typically thick shrub layer
of rosebay rhododendron, which precludes most herbaceous growth.
These forests are typically large statured with uneven canopies
usually around 120' high and trees frequently exceeding three feet
diameter. On gentle topography along streams and in north facing
coves, these acidic cove forests occasionally give way to more
hardwood dominated rich cove forests, the botanical stars of the
Smokies and the Appalachian Mountains. These forests have gained
their notoriety by supporting spectacular displays of spring
wildflowers and massive trees. The overstory is mixed, but typically
includes many sugar maples, yellow buckeyes, white basswoods, and
silverbells. Tuliptree and hemlock may also form substantial parts of
the canopy, and tuliptrees reach their largest sizes in this
community. Below the large hardwoods, the sparse understory sometimes
includes striped maple or mountain maple, but is composed primarily of
saplings of shade tolerant overstory species: yellow buckeye,
silverbell, and sugar maple. The rich soils support even greater
diversity in the thick herbaceous layer that often includes large
flowered trillium, spring beauties, squirrel corn, Dutchman's
britches, foam flower, black cohosh, yellow mandarin and blue cohosh
among others. In narrower coves, which often feature boulderfields,
the composition usually shifts to include more squirrel corn and
Dutchman's britches in the herbaceous layer, more mountain maple in
the understory, and more yellow buckeye and Dutchman's pipe vine in
the canopy.

In the rainforest conditions that occur at higher elevations, the
forests vary much less with topography. The broad domes of yellow
birch crowns and narrow cones of red spruce crowns form a strongly two
tiered canopy that stretches from the streams to the ridge crests. On
the high peaks and ridges, that community extends from about 6000'
elevation down to around 4500'; in highly sheltered north facing
drainages that begin at high elevations, spruce and birch may maintain
dominance down to around 4000' elevation. The overstory often
includes many large gaps that allow substantial light to reach the
highly variable understory. Mountain maple frequently thrives in
those gaps along with witch-hobble, saplings of larger tree species,
and a dense herb layer that may include umbrella leaf, Rugel's
ragwort, heartleaf aster, and an abundance of ferns and mosses.
However, the understory more commonly consists of an interwoven tangle
of rhododendron, more often rosebay than catawba, that grows more
horizontally than vertically, and can exclude all other vascular
plants. In those areas, tree regeneration occurs primarily on fallen

Above that forest, on top of Mount Le Conte and Mount Guyot and along
the ridge connecting them, Fraser fir becomes a successful competitor.
At the highest elevations, the fir grows in extremely dense stands
interrupted only by scattered red spruce and mountain ash. Going down
slope, spruce gradually replaces fir, although Fraser fir may still
form dense stands in the understory. The shade in the fir stands may
be dense enough to preclude any vascular plants from growing
underneath them. However, the balsam woolly adelgid has made such
stands far scarcer than they were a few decades ago by killing the
vast majority of mature fraser fir, and in places leaving behind ghost
forests of standing, bleached trunks that rot slowly in the
waterlogged, cool climate. Yet, some of the dense fir groves that
have grown back since the first wave of adelgid induced mortality are
already maturing since Fraser fir grows relatively quickly, only
reaches about 40' tall on most sites, and the adelgid does not attack
until after the trees mature.

The extensive tract of uncut, high diversity, high productivity forest
spanning Greenbrier's middle elevations has made the area a focus of
ENTS in the south for the organization's entire history. Before ENTS,
visitors, the park naturalist, and others were nominating champion
trees from Greenbrier. Hence, the plethora of record trees known from
the area reflects not only the high productivity and history of
protection of the forests, but also extensive active searching.
However, exploration of other sections of the southern Appalachians
has revealed no other area with the abundance of massive hardwoods
that Greenbrier boasts. The 2006-2007 National Register of Big Trees
lists six national champions in Greenbrier; three of those have now
fallen, but a larger tree has been found in Greenbrier for one of the
fallen trees and two additional potential champions have been located.

Greenbrier also ranks high by the method ENTS often uses to evaluate
sites, the Rucker Index.

Rucker Height Index: 150.9'
Tuliptree 173.4'
Eastern Hemlock 165.3'
Yellow Buckeye 157.3'
Black Locust 151.3'
White Ash 149.0'
Bitternut Hickory 146'
Red Maple 142.6'
Northern Red Oak 141.8'
Sycamore 141.7'
Black Cherry 140.7'

The Rucker Index includes: eight trees in old-growth forests and two
in second growth forests; three eastern height records (buckeye, red
maple, and black cherry); and seven state height records. The 150.9'
value ranks fifth in the eastern US behind two other sections of the
Smokies, Savage Gulf, and Congaree NP. The index is the second
highest in TN behind Savage Gulf. The two tallest trees in the index
were both located in 2006, so the index continues to change.

Rucker Girth Index: 17.7'
Tuliptree 25.3'
Sycamore 18.75'
Eastern Hemlock 18.4'
Northern Red Oak 18.4'
Black Cherry 17.9'
Red Maple 16.9'
Yellow Buckeye 16.7'
White Ash 15.9'
Chestnut Oak 14.85'
Cucumbertree 14.1'

All ten of the trees in the girth index grow in old-growth forests.
The hemlock, northern red oak, and red maple are each likely the first
or second largest known in volume for their species. The red maple
and white ash were both found in 2006.

Most areas in Greenbrier below 4000' and known to have uncut forests
on gentle topography have been visited to look for large trees.
However, much less attention has been paid to slopes and steep-sided
stream corridors. Those sites can also support highly productive
forest, but harbor record size trees much less frequently. The cloud
shrouded high elevation forests maintain the greatest air of mystery
in Greenbrier. In streamside areas, only one short section of trail
extends above 4000' elevation, so the forests have received extremely
little visitation. Remoteness, boulder filled stream channels, and
extensive rhododendron thickets may hide other exemplary forests in
the area's upper reaches.

Jess Riddle
Re: Greenbrier, GSMNP   Lee E. Frelich
  Feb 06, 2007 07:09 PST 


The rich site with Trillium and spring ephemerals sounds great. There must
not be a high deer population there, and the European/Asian earthworm
invasion being tracked by Paul Hendrix and coworkers at U Georgia must not
have reached the area yet. Such areas are slowly disappearing all across
the eastern U.S. Chris Webster at Michigan Tech University has been
studying deer in the Smokies and has found a similar damage pattern to
native understory flora in certain areas with high deer populations to that
we find up here. You should look up some of his recent publications.

Re: Greenbrier, GSMNP   Jess Riddle
  Feb 13, 2007 19:35 PST 


Thanks for letting me know who's leading the research on deer and
earthworm impacts on the Smokies. I will look up their current

From what I've seen, largely intact herbaceous layers are still much
more common in the park's old-growth forests than heavily disturbed
herb layers. I would guess that most of the deer damage is occurring
around Cades Cove, which has by far the largest fields in the park and
smaller mountains in the immediate vicinity. I've always had the
impression that, on a park-wide basis, feral hogs are much more
destructive than deer to the native flora.


RE: Greenbrier, GSMNP   James Smith
  Feb 15, 2007 16:20 PST 

I spoke to a ranger in Cades Cove a few years ago (a park naturalist).
She was very happy over the fact that coyotes were so well established
in the park. They had, she said, filled in the niche formerly occupied
by wolves and were serving pretty much the same function. It was her
belief that the coyotes were having a positive role in controlling the
populations of both deer and feral hogs. She told me that coyotes were
taking quite a lot of young hogs.