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8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
1/81
Vegetation of the Great Smoky Mountains
R. H. Whittaker
Ecological Monographs, Vol. 26, No. 1. (Jan., 1956), pp. 1-80.
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8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
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VEGETATION OF THE GREAT SJlOKY l l lOUSTAINS1
R
WHITTAKER
Biology Department . Brooklyn Col lege. Brooklyn
10
X
. Y
T A B L E
O F
C O N T E S T S
P A G E
In t roduct ion
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
1
N a t u r e o f t h e S t u d y
. . . . . . . . . . . . . . . . . . . . . . . . . . 1
Li tera ture on Area . . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Acknowledgments . . . . . . . . . . . . . . . . . . . . . . 2
Geology and Climate . . . . . . . . . . . . . . . . . . . . . . . . . . 2
Methods
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Field Transec ts and Tre e Classes . . . . . . . . . . . . . .
4
Si te -Samples and Compos i t e Transec t s
. . . . . . . . . . 6
Dis t r ibu t ions o f Spec ies a long the Mois ture
Gradien t . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
8
T r en d s i n R e l a t i o n t o t h e M o i st u re G r a d ien t . . . . . .
10
Growth-Forms
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Coverages . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Diversities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
10
Sizes and Numbe rs of S tems o f T rees . . . . . . . . . .
11
S e l f - M a i n t en a n ce o f S t a n d s . . . . . . . . . . . . . . . . . . . . 11
High-Elevat ion Deciduous Fores ts . . . . . . . . . . . . . . . . 13
Dis t r ibu t ions o f Spec ies in Rela t ion to E levat ion . . .
X es i c S i t e s
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Submes ic S i t es . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Subxer ic S i t es . . . . . . . . . . . . . . . . . . . . . . . . .
Xer ic S i t es
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Trends in Rela t ion to E levat ion . . . . . . . . . . . . . . . .
Growth-Forms . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Tree S ta tures and S t ra ta l Coverages . . . . . . . . . . . . .
Divers i ty and Environmental Favorableness
. . .
Spruce-Fir Fores ts . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Stratal Dis tr ibut ions . . . . . . . . . . . . . . . . . . . . . . . . . .
T r en d s
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Relat ions o f Species to Union s and Associat ions . . . .
C o n t i n u i t y o f V eg e t a t i o n T yp es . . . . . . . . . . . . . . . .
Nature of Species Group ings . . . . . . . . . . . . . . .
Dominance in Rela t ion to Comm uni ty Compos i t ion
Summ ary o f D ist r ibu t ional Groupings . . . . . . . . . . . .
I 1
D I S C U S S I O N : OFN I N T E R P R E P A T I O N
\ T F X 3 ~ ~ ~ ~ ~ . . . . . . . . . . . . . . . . . . . . .
ATTERNING
~
Dis t r ibu tions o f Spec ies and the S tu dy o f Genecology
T he Assoc ia t ion-Uni t The ory and Indiv idual is t i c
Hypothes i s . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
T h e Dis tr ibu t ional Bas i s o f Communi ty .Types
. . . . . .
Gradat ion and the Grouping o f Spec ies . . . . . . . . .
I . G R A D I E N T A N A L Y S I S
I N T R O D U C T I O N
NATURE
O F
T H E
S T U D Y
T h e Great
Snloky
Mountains of Tennessee
and
N o r t h C a r o l in a s u p p o r t v e g e t a ti o n w h i c h i s p a r ti c u-
' 1 ~ ''''
i n s ~ e c i e s n d v a ri ed in c o m m u n i t y t y p e s
I n t h e s u mm e r o f 1947 f ield w o rk \&*as carr ied o u t
Based on a thesis Whittaker
1 9 4 8 ;
a contr~bution rom
the Department of Zoology. University of Illinois . LTrbana.
and
the Biology Department. Brooklyn College
Zonat ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
34
Ecotones
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
36
Climax Pat terns and Their Comparison . . . . . . . . . . . . 37
Considerat ions o f Logic and Zlethod . . . . . . . . . . . . . . 40
Conclus ion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
43
111
\ T E G ~ ~ 4 T 1 0 ~ T H E I R I S T R I B U T I O N A LY P E SA X D
R E L A T I O N S. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
43
Bases o f Recogniz ing and Descr ibing Ty pe s
. . . . . . . .
43
V eg e t a t i o n T yp es o f t h e G r ea t S m o ky M o u n t a i n s
. . .
45
1
Cove Hardwoods Fores t . . . . . . . . . . . . . . . . . . . . . 45
Mixed Mesophyt ic i n the Smokies and
Cumberlands . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
2. Eastern Hemlock Fores t . . . . . . . . . . . . . . . . . . . . . 48
3
Gray Beech Fores t
. . . . . . . . . . . . . . . . . . . . . . . . . 48
4 Red Oak-P ignut H ickory Fores t . . . . . . . . . . . . . . 49
5
Chestnut Oak-Chestnut Fores t . . . . . . . . . . . . . . . . 49
6. Ches tnut Oak -Ches tnut Heath . . . . . . . . . . . . . . . 50
7
. Red Oa k-Chestnu t Forest . . . . . . . . . . . . . . . . . . . . .51
8
.
Whi te Oak-Ches tnut Fores t
. . . . . . . . . . . . . . . . . .
Pine S ta nds and Thei r Nain tenance
. . . . . . . . . . . . .
9. Virg in ia P ine Forest . . . . . . . . . . . . . . . . . . . . . . . .
10. P i t ch P i n e H ea t h . . . . . . . . . . . . . . . . . . . . .
11
.
T a b l e V o u n t a i n P i n e H e a t h
. . . . . . . . . . . . . . . .
12. Grassy Bald . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
The Southern Appalachian Subalp ine
Fores t Center . . . . . . . . . . . . . . . . . . . . . . . . . . . .
13. Red Spruce Forest . . . . . . . . . . . . . . . . . . . . . . . . .
14 Fraser Fir Fores t . . . . . . . . . . . . . . . . . . . . . . . . . .
15. H ea t h B a l d . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
Th e Balds as Topographic C l imaxes?
. . . . . . . . . . . .
Distributional Relations . . . . . . . . . . . . . . . . . . . . . . .
T h e X o s a i c C h a rt
. . . . . . . . . . . . . . . . . . . . . . . . . . . .
Dis t r ibu tions o f Ty pes . . . . . . . . . . . . . . . . . . . . .
Distr ibut ion of f lubalpine Fore s ts
. . . . . . . . . . . . . .
Rela t ion of the Vege ta t ion Pat tern to Those
o f O t her V o u n t a i n R a n g es . . . . . . . . . . . . . . . . .
Suncnca~.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
LI TE RA TU RECIT ED
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A P P E N D I X E S
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
A
. Popula t ion Char t s for Major Tree Spec ies
. . . . . .
Kote on Supplementary Publ ica t ion o f Appendixes
B and . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
f o r a s t u d y o f t h i s v e g e t a ti o n . T h e w o r k w a s o r ig i-
n a l l y i n te n d e d t o p ro v id e i n f o r m a t i o n o n t h e v e g e -
t a t i o n f o r t h e s a k e o f i t s o w n i n t e r e s t a n d a s a b a s is
f o r s t u d i es i n a n i m a l e c o lo g y ( W h i t t a k e r
1 9 5 2 )
.
A
m a j o r p u r p o s e o f b o t h th i s a n d t h e pr e ce d in g s t u d y .
h ou -e ve r. u -a s u s e o f t h e c o m p l e x p a t t e r n o f n a t u r a l
communities
in
the Great Smoky
Mountains
f o r
re-
search
into
t h e t h e o r y
comlnunity u n i t s o r a s so -
.
F~~
t h i s purpose. t h e
approachto
vegeta-
t a t io n w a s ba se d o n s a m p l i n g w i t h o u t r e g a rd t o a p -
p a r e n t a s s o c ia t i o ns a n d a n a l y s i s o f t h e s a m p l e s i n
8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
3/81
relation to environmental gradients. I t was felt that
relative validity of vegetation types should emerge
from data impartially obtained, and that the rela-
tions of types to one another should be revealed in
the study of their populations in relation to environ-
mental gradients. The work thus depart s from the
traditional approach of studying intuitively recog-
nized types or associations; it is an experiment in
population analysis of a whole vegetation pat tern .
The first part of the monograph describes results
of the analysis in terms of relations of species popu-
lations to one another and environmental gradients,
and trends in community composition and structure
along environmental gradients. The second par t in-
terprets the vegetation as a complex pattern, within
which vegetation types may be understood through
the distributional relations of species populations.
The third part presents a more conventional de-
scription of vegetation types and considers the re-
lations of these to topography. The study as a whole
thus seeks to analyze, interpret, and describe the
complex vegetational mantle of the Great Smoky
Mountains.
LITER TURE O N RE
A series of studies by Cain deal with vegetation of
the Smokies-the heath balds (1930b), subalpine
forests (1935), and cove hardwoods (1943), floristic
affinities (1930a), soil reaction (1931), Raunkiae r
life-forms (194 5), and bryophyte unions (Cain
Sharp 1938). A number of vegetation types were
described by Cain
e t
al (1937). The grassy balds
were reported on by Camp (1931, 1936) and Wells
(1936a, 1936b, 1937); the subalpine forests were
recently described by Oosting Billings (1951) and
the beech gaps by Russell (1953). These papers and
the description in Braun (1950) are the extent of the
literature dealing specifically with the vegetation of
the Smokies. Other studies include descript ions of
Southern Appalachian vegetation types, among then1
Harshberger's report (1903) and book (19 11) , Wells
(1924) and the forestry reports of the l essage fr o m
the Pres ident
(Ayres Ashe 1902), Reed (1905),
Holmes (1911), Ashe (1922), and Frothingham
et
al (1926). Of studies in nearby areas Braun's papers
on the Cumberland Mountains-Pine Mountain
(1935b), Black Mountain (194 0a), and the Cumber-
lands (1942, 1940b)-and material in the book on
the eastern forests (1950) were most valuable for the
related vegetation of the Smokies. Other Appalachian
and eastern studies-Harshberger (1905) and Heim-
burger (1934) on the Adirondacks, Core (1929) on
Spruce Mountain, Davis (1930) on the Black hIoun-
tains, Conard (1935) on Long Island, Raup (1938)
on the Black Rock Forest, Oosting Billings (1939)
on Ravenel's Woods, Oosting (1942) on the Pied-
mont, and, particularly, Brown (1941) on Roan
Mountain-contributed
conlparative information. A
bibliography of other paper s dealing with the Smokies
is given by Mason Avery (1931) . Taxonomic ref -
erences for the area are Small (193 3), Shanks
Sha rp (1947), Gleason (1952), and Fernald (1950).
ITTAKER
Ecological Monographs
Vol. 26 No. 1
While at the University of Illinois, the author was
aided by the suggestions and criticisms of S. C. Ken-
deigh and A.
G
Vestal. The pa rk naturalist of the
Great Smokies, Arthur Stupka, gave the author the
cooperation and benefit of broad knowledge of the
mountains which he extends to students in the area.
Help with the identification of plant specimens \&*as
given by Stupka and by A. J Sharp and R.
E
Shanks, m*ho checked all determinations Responsi-
bility for statements of distribut ion, based on field
deteriiiinations, remains with the author. A number
of people have read part or all of the manuscript
and offered comments on it:
E L. Braun, H. E.
Brewer, H . K . Buechner, TIT. H . Camp, A Cronquist,
R. Daubenmire, F E Egler, H. A. Gleason,
A
R.
Kruckeberg, H
L
Mason, R. E Shanks, A.
F
Sharp,
and A. Stupka. The author is especially indebted to
mT.
H. Camp for his suggestions and for information
which permitted interpretation of genetic and dis-
tributional phenomena. Cost of publ icat~on of the
tables and charts has been met in part by a grant-in-
aid from the Society of the Sigma Xi.
GEOLOGY ND CLI X TE
The Great Smoky hlountains are part of the Blue
Ridge Province, a systein of mountains of great an-
tiquity. This pa rt of the Southern Appalachians
comprises two major ranges, the Blue Ridge proper
and the Cnaka blountains, along with their con-
necting cross-ranges (Fennem an 1938). The two
main ranges lie parallel, from northeast to ~outhwest,
with the 17nakas, of which the Smokies are part, to
the north. The drainage, north from the dlvide of
the Blue Ridge, is northwest into the Great Valley of
the Tennessee R i ~ e r , nd rivers flowng from the
Blue Ridge to the Great Valley through the ITnakas
cut the latter into
a series of segments divided by
deep gorges. The Great Smoky Mountains are the
largest and highest of these segments, between the
Little Tennessee and Big Pigeon Rivers.
The crest of the Great Smoky hlountains forms
the state border of Tennessee and North Carolina, 25-
50 miles southwest of the city of Knoxville in the
Great Valley. The range has the appearance of a
long, sinuous ridge connecting irregularly spaced
domes, with secondary ridges and hills spreading on
each side (Fig. 1 . The mountains are stream-eroded
to physiographic maturity; in form they are sub-
dued (Fenneman 1938) though rugged. Many of the
summits and ridges are rounded, and almost all the
mountain surface is covered by a mantle of soil and
vegetation. The resistant rocks have maintained high
relief in spit e of age. Sixteen peaks have elevations
above 6000 f t (1830 m) and the highest sunl n~i ts ise
more than 5000 f t above the valleys a few miles to
the north. Valleys are cut deep into the mountain
mass, with steep slopes and narrow flats. The slopes
for111 most of the area of the mountains; it has been
estimated tha t less than 10 of the surface has less
than 10 degrees of slope (Message from the Presi-
dent 1902).
8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
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anuary
1956 VEGETATION
MOUNTAINS
F THE GREATSMOKY
FIG 1 Matu re, forest-covered topog raphy of the
from Frye Mountain near Bryson City, North Carolina
tanooga, Tenn.
Most of the rocks of the mountains belong to the
Ocoee series Saf for d 1869, Stose Stose 1944, 1949,
Ki ng 1 949) of complexly folded, metamorphic sedii
mentary rocks which are resistant to erosion and
fairl y uniform in their reaction to it . Deposited in
Cambrian or late pre-Cambrian time Ke ith 1902,
Stose Stose 1949, Ki ng 19 49) ) hey were first folded
into mountains in the Appalachian Revolution of
the late Paleozoic. The mo untain s were raised
fur ther in the Cre taceous and have s ince tha t t ime
been through three cycles of erosion, the Schooley,
Ha r r i sburg , a nd p re sen t Wright 1931) . While some
higher ridges of the Smokies may remain from the
Schooley cycle of the earlier Tert iary W illis 1889,
Ki ng Stu pk a 195 0)) i t is probable tha t throughout
this the area was one of hills or low mountains Fe n-
neman 1938, Wright 1942, Braun 1950) . Afte r a
second elevation, probably in the Miocene, the moun-
tains persisted through the shorter Harrisburg cycle,
the peneplane of which may be suggested by some of
the lower ridges K in g
Stupka 1950) . The moun-
tains were again raised at the end of the Tertiary.
During the Pleistocene the Smokies were well south
of the ice sheets and possessed no glaciers; but there
are indications that climatic cooling produced a tim-
ber line on the higher summits Ki ng Stu pk a 195 0) ,
displacing forest vegetation toward lower elevations.
I t is believed, from distribu tional evidence discussed
later P ar t 111) that high-elevation forests were dis-
placed u pw ard 1000 to 1300 ft above present levels
during the warm dry period following glaciation.
Great Sm oky Mo untains , a view of the sou theast slope
.
Reproduced by permission of
W
M. Cline Co., Chat-
The southern mountains have played a great part
in the vegetational history of the Ea st Br au n 1938,
1941, 195 0). While other are as have been glaciated,
submerged, and exposed to great climatic change
Ferna ld 1931)) the Sou thern Appalachians have
offered
a
sanc tuary for many spec ies of plants and
animals. The Blue Ridge System has been con-
t inuously occupied by p lants and animals for pe rhaps
200 million years Ca in
t
a l . 1937) . During the
early Tertiary the higher elevations of the Smokies
and Blue Ridge probably supported tempera te for-
ests ancestral to those now in the area while sub-
tropical floras prevailed at sea level Ca in 19 43 ).
I t is in the Blue Ridge Province and other a reas
where the Schooley peneplane was never perfected
that most typical mixed mesophytic forests, most
closely related to the Arctotertiary forests, have sur-
vived Brau n 1950 5 0 5 ) . Du ring the cl imatic changes
to which eastern vegetation was subjected, the topog-
raphy of the Southern Appalachians offered varied
conditions of moisture and elevation in which species
of diverse climatic adaptations might survive while
sometimes destroyed elsewhere.
I t might be expected that age and maturity of the
mountains would be reflected in maturity of their
pla nt cover, as well as in antiquity of some of the
flora. Pr im ary succession is nearly completed in the
Smokies ; i t is perhaps in progress on a few peaks
and ridges, but almost all the vegetation is either
topographic climax or secondary. One of the majo r
for rs t t rees , the ches tnut Cas tanea dent a ta ) , wae
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8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
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January 1956
VEGETATION
THE
GR
F
stems nere the usual sample for each of
7
to 1 0
stations. Along with the tree count the undergrowth
was recorded by a coverage estimate for each stratum
and a list of major and minor species. An example,
one of six such transects made, will show the method
and its relation to the composite transects.
On the Bullhead Trail to Mt. Le Conte, seven
sample counts nere made at intervals of 5 m from
the valley bottom to the southwest-facing slope, all
a t elevations of 3100 ft . I n the tables an additional
sample from a deep valley forest was added to the
beginning of the series, since the small valley of the
transect did not represent the extreme of mesic con-
ditions. Percentages of stand for the tree3 and oc-
currences of shrubs and herbs were arranged for the
8 stations as in Table 1 . I n analyzing transects with
relatively small samples, simple tallying of numbers
of stems fo r each species was preferred to basal-area
computation. Canopy dominance was determined
separately from larger samples.
Individual species of trees are well scattered along
the gradient, but certain loose groupings of species
may be suggested. Some species have their maximum
abundance in the deep-valley cove forest, station K
of the transect. or are abundant there and have their
TABLE
1
Bullhead field transect of moisture gradient.
Along trail from Cherokee Orchard to Mt. Le Conte, in
a small dry valley at
3100
ft and out onto adjacent
southwest slope. Trees
by
percentages of stand from
1-in. class up.
Tree species K I I1 111 IV
V
VI VII
Tsuga canadensis..
. . . . . . . . .
Halesia monlieola . . . . .
Aesculus octandra. . . . . . . . . . .
dce r saccharum . . . . . . . . . . . .
Tili o heferophylla. . . . . . . . .
Fagun grandifolio. . . . . . . .
Betula allegheniensis.
. . . . . . .
Liriodendron tulipifma. . . . . .
Magnolta acuminata . . . . . . . .
Ilez opaco . . . . . . . . . . . . .
Carye cordiformis . . . . . . . . .
Frazrnus amencana
. . . . . . . .
Cladrastts lulea
. . . . . . .
Magnolio f.asert . . . . . . . .
Acer rubrum. . . . . . . . .
Qtrncus borealis v. moz mu
Carya globra.
. . . . . . . . . .
Oslrya virginlona
. . . . . . .
Acer pensylwnvum . . . . . . .
Belula lenta . . . . . . . . . . . . .
Hamamelis mrginiona . . . . . . .
Cle lh~a c um im ta . . . . . . . . . .
Amelanchier arborea. . . . . . . .
Robrnio pseudoam .
. . . . . .
Castanea d enhta
( d e a d ) .
. . . . .
Quercus pr inus ..
. . . . . . . . . . .
Ozydendrum arboreum.. . . . . .
Nwxa xylwlico.
. . . . . . . . . . .
Sassafras altndum.
. . . . . . . .
Quercus coccineo.. . . . . . . . . .
Pinus pungena.
. . . . . . . . . . . .
Pinus r ig ido . .
. . . . . . . . .
Total stems. . . . . . . . . .
a
present at leea than
,575,
*Kalanu Flats, a cove forest
6 mi.
east of transect area, elevation 2800 ft.
maxima in the second or third stations. Bt the other
extreme are species which have their maxima in the
most xeric site, station VII, and do not extend to
sites less xeric than station VI. Between these ex-
treme groups there are a number of species with
their maximum populations in stations 111 to VI.
These might be grouped together; but they may also
be separated into two groups, one having maxima in
stations 111 and IV, extending on the mesic side to
station
I
or
I1
but not beyond V on the xeric side,
and the other having maxima in stations
V
and V I
and extending to the xeric extreme, but not beyond
I V on the mesic side. The four groups are used as
classes of trees along the moisture gradient. They
may be characterized as follows:
1
Mesics-Species with maxima in or near the
most mesic sites and with limited extent into more
xeric situations, occurring rarely in the part of the
gradient represented by oak-chestnut heath. These
species predominate in the cove forests.
2. Submesics-Species which have the ir maxima in
fai rly mesic sites, but a re uncommon or absent in
most mesic sites and do not extend to most xeric sites.
These species predominate in oak-hickory forests at
lower elevations and in red oak-chestnut forests a t
higher elevations.
3 . Subxerics--Species which have their maxima in
more xeric sites, but occur in most xeric sites only as
minor species and are absent from most mesic sites.
These species predominate in oak-chestnut heaths and
at higher elevations in white oak-chestnut forests.
4. Xerics-Species which have their maxima in
most xeric sites and have limited extent into less
xeric iit es , extending into the range of dominance of
the previous group and no further. These species
predominate in pine forests and pine heaths.
The same classes are recognized for shrub and
herb populations. Lists of species fo r each are given
in the Summary of Distributional Groupings.
The moisture gradient is one of g reat complexity;
along the gradient from stream-side to south-facing
slope and ridge many factors of soil moisture and
atmospheric humidity vary, along with exposure to
wind and insolation, and factors of temperature af-
fected by insolation and by patterns of air move-
ment. In relation to the primary gradients of en-
vironmental factors a sequence of vegetation types
and a catena of soils develop; and the composition
and physiognomy of vegetation and properties of
soils form other secondary gradients of environ-
mental factors affecting plants. The primary factors
are so modified by the presence of plant communities
that primary and secondary factors are not
really to be distinguished in their effects on plants.
At any point along the gradient the plant lives in
relation to an environmental complex of interrelated
factors of physical environment, soil, vegetation,
and animal communities; along the moisture gradi-
ent factors of each of these change. The gradi-
ent is thus a complex of factor gradients, or a gradi-
ent of environmental complexes, which, in distinc-
8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
7/81
t ion f rom a f ac to r g r ad i cn t , may be t e rmed a
c o m -
p l e x - g r a d i e r ~ t
(Whi t t ake r 1954b) . The " e l eva t i on
grad ient" is l ikewise a complex-gradient , involving
many fac tors of phys ica l envi ronment , so i l s , and
na tu ra l communi t i e s o the r t han t empera tu re s and
growing seasons .
The complex-gradient f rom val ley bot toms to dry
slopes wil l be cal led the "moisture gradi ent ," bu t
wi th no a s sumpt ion t ha t mo i s tu r e f ac to r s d i r ec t l y
cont ro l the d is t r ibut ion of an y p la nt popula t ion a lon g
it . Jfeasurernents of all ' fac tor s of env ironm ent an d
determination of which may be most s ignif icant for
popula t ions of d i f fe rent p lant spec ies a re f a r beyond
the scope of the present work. F or the present s tud y
i t may suf f ice tha t a complex-gradient ex is t s , in re -
la t ion to which the d is t r ibut ions of p lant popula t ions
may be studied.
Such study is dependent on the defini t ion of rela-
t ive posi t ions along the grad ient . Since these could
not be de termined, f o r hundr eds of s i te -samples ,
by d i r ec t env i ronmen ta l measu remen t , app roaches
through the vegeta tion i t se l f were sought . Along the
gradient the four mois ture c lasses of t rees r i se and
fa l l in sequence , form ing a se t of cu rves f lowing
cont inuous ly in to one anothe r (Fi gs . 2 , 3 , 4 . I f , a s
is s h o ~ v ~ ly the t ransec ts , there i s progress ive sh i f t in
proport ions of t rees of different tolerances along the
gradient , then i t i s not unreasonable to tur n f r om
th i s f ac t t o i t s conve r se and r ega rd t he s ame p ropor -
t ions as express ions of pos i t ion a long the gradient .
I n the fo l lowing d iscussion, s tan ds an d s i tes wi ll be
termed
mesic , sz bmesic , subxer ic ,
a n d
xe r i c
according
to which of the moisture classes pred om inate i n stem
numbers.
SITE SAMPL ES AND COhlPOSITE TRANSECTS
The main re l iance in so lv ing the vegeta t ion pa t -
te rn was on the s i te -samples and the i r manipula t ion .
s i t e - s a m p l e
was a vegeta t ion sample f rom a re-
str icted si te of unifo rm physical habitat- the f loor of
a
valley, a s ingle hi l ls ide slope of the sam e direct ion
and inc l ina t ion, or the c res t of a r idge . I n order to
ob t a in an app rox ima te ly r andom coverage o f t he
whole vegeta tion pa t te rn , samples were take n f rom
the many t ra i l s a t a l l e leva t ions in the mounta ins .
The method was to move a long a t ra i l recording a
sample f rom each new s lope exposure , ins ide or out
of a valley, of sufficient extent to give a homogene-
ous sample. The si te-samples were in no case se-
lec ted to represent e i ther apparent vegeta t ion types
or the t rans i t ions be tween them.
The bulk of the si te-
s amples were ob t a ined f rom the moun ta ins su r round-
ing Greenbr i e r , Suga r l and , and Cades Coves i n t he
Ka t iona l Pa rk on t he Tennes see o r no r thwes t s i de
of the range .
A t each s i t e t he s ame da t a were r eco rded a s i n t he
t ransec t s ta t ions . Sample s ize var ied wi th the num-
her of t rees thought necessary to indica te s tand com-
posi t ion: f i f ty were suff icient in some stands with
one or two dominants , but most counts inc luded about
100, while 200 or 300 were tal l ied f o r some mixed
types . The dense smal l s tems of Rhod odendron
Ecological Monographs
Vol.
26,
No.
th icke ts were not counted in fores t s where they oc-
curre d. T he 25,000 stems recorded in 300 si te-samples
were the to ta l sample ana lyzed for the vegeta t ion
pa t t e rn .
Exact lng phytosocio logica l ana lys is of the under-
g rawth mas no t an ob jec ti ve. I n fo rma t ion on sh rubs
is la rge ly l imi ted to presence and s t ra ta l dominance ,
t h a t
on
herbs to visible presence a t the t ime of sam -
pl ing . S t ra t a l coverages a re es t imates , in tended only
to permi t cornpar i sons be tween d i f ferent s tands in
t h e S m o k ie s. A t 1 5 s a m p le s t at io n s f o r a n o t h e r s t u d y
(W hi t t a ke r 195 2) l oca ti on and coverage of i nd iv idua l
p l an t s we re mapped i n quad ra t s 10m squa re .
The s i te -samples were ma nipu la ted in severa l ways .
By compar ing s e r i e s o f t hem f rom nor th and sou th
slopes or other exposures, the al terne effect on vege-
ta t ion could be de termined, a method found par t icu-
larly effect ive at high elevat ions where al terne effects
are more conspicuous in undergrowth than canopy.
G r o u p s o f s a m p le s f r o m s it es w ~ t h i m i la r m o l s tu r e
condit ions within l imited ranges of elevat ions were
compi led in to composi te s tand counts . These counts ,
u s ua ll y f o r a b o u t 1 0 0 0 st em s , c o m p e n s a t ~ d o r t h e
s lna l l s ize of the s i te -sample counts and were used
fo r t he cha rac te r i za ti on o f vege ta t ion t ypes ( P a r t
111 ) . Da t a f rom the s l te - samples were a r r an ged i n
mosaic form on a char t wi th e leva t ion and topo-
graphic s i tes as axes , to show dis t r ibut ion? of spec ies
2nd vege ta t ion t ypes i n r e l a ti on t o e l e v~ t io n and
t o p o gr a p h y ( P a r t 1 1 1 ) .
The site-samples were, f inal ly, arr ang ed in
c o m -
pos i t e t ranse c t s
in te rms of e leva t ion , or of topo-
grap hic s i te , or of mo is ture condi tions as indica ted
hy the vegeta tion i t se l f. F o r the e leva t ion t ransec ts
come means of c om pa rin g sta nd s of equivalent mois-
ture condit ions at different elevat ions was needed.
The si te-samples were consequently classif ied into
fo ur group s , according to which of the m ois ture
c las ies of t rees was predonl inant in a g iven sample .
TT1thin each of the four classes of s tands, the si te-
samples were grouped by 200- and 300-f t in te rva ls .
F ou r compos it e t r ansec t s we re t hus a r r ang ed t o cove r
thc whole of the vegeta tion pa t te rn , showing the
change in leve ls of p lant popula t ions f rom low e le-
va t ions to h i& in each of the fou r classes of s tands
and si tes recognized.
A more sens i t ive indica t ion of re la t ive pos i t ions
a long t he mo i s tu r e g r ad i en t i s pos s ib l e t h rough the
use of
w e i g h t e d a v e r a g e s
as indica tor va lues (c f .
El lenberg 1948, 1950, 1952, Cur t i s McIntos h 1951,
w h i t t a k e r 1 9 5 4 b ) .
I n a g i ve n s t a n d t h e n u m b e r
of s tems in each moisture class is mult ipl ied by a
we igh t ( 0 fo r mesi cs , f o r submes ic s, 2 fo r sub -
xer ics , 3 f o r xer ics ) , a nd the to ta l of weig ~ted s tem
numbers i s d iv ided by the to ta l number of s tems.
Within elevat ion bel ts (1500-2500, 2500-3500, and
3500-4500 f t ) t ,he s i te-samples were ar ran ge d in se-
quence f rom most mes ic to most xer ic by these
we igh t ed ave rages , and were t hen g rouped fo r t abu -
l a t ion i n t, o 1 2 o r 1 3 s t eps a long t he g rad i en t . Th i s
method of , a r ra ngin g the t ransec ts involves an evi -
8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
8/81
anuary,
1956 VEGETATION TIIE
~ ~ O U N T A I N SF GREAT
SMOKY
t l en t c i rcu la r i t y ; d i s t r ibu t ion of t ree spec ies i s s tud ied
in t e rms of prev ious ly de t ermined d i s t r ibu t iona l
c l asses of t hese sa i ii e t ree spec ies . The a pp ro ac h i s
based , however , on the objec t ive d a t a of t h e f ie ld
t r ansec t s ; and t he pa t t e rn s o f spec i e s d i s t r i bu t i ons
a re e i i en t i a l l y t he s am e i n t he f i e l d t r an sec t s and
composi t e t ransec t s .
O t he r com pos i te t r an se c t s w e re m ade fo r e l evat ions
nhove 4500 f t i n suba l p i ne o r sp ruce - f i r fo re s t s, a nd
i n h i gh -el eva t ion dec i duous fo re s t s ou t s i de t he r an ge
o f sp ruc e and f i r. I n t he se the s am p l e s w e re g roup ed
by t opog raph i c pos i t i on r a t he r t han by w e i gh t ed
ave rages . T he va r i ous com pos i t e t r an sec t s w e re de-
s i gned t o fo rm a g r i d cove r i ng t he w ho le o f t he yege -
t a t io n p a t t e r n o f t h e G r e a t S m o k y M o u n t a in s . T h e
fo l lowing sec t ions wi ll d i scuss d i s t r ibu t ions of p l a n t
popu l a t i ons and t r ends i n com m un i t y com pos i t i on
show n by these t ransec t s . The whole body of t ab l es
can not be publ i shed here . Two tab les hav e a l rea dy
b ee n p u b li sh e d ( W h i t t a k e r 1 9 5 1 ) , a n d t h e o t h e r
t a b le s f o r t r e e p o p u l a t i o n s a r e p r e s e nt e d h e r e ( w i t h
extens ion of e l eva t ion in t e rva l s f r om
200
t o 4 00 f t
i n t ab l e s 5 and
6 ) .
T he fu l l se t o f t ab l e s fo r t r e e
popu l a t i ons a nd unde rg row t h spec ie s a r e ava i lab l e
t o t hose de s i r i ng t hem ( see N o t e on S up p l en i en t a ry
P ub l i ca t i on )
TABLE2.
Composite transect of moisture gradient between
2500
f t a n d
3500
f t , dist r ibut ion of t rees along gradi -
en t. Transect along the moisture grad ient fr om mesic valley si tes ( Sta .
1 )
to xeric southwest slope si tes (Sta.
13),
based on 67 site counts including 6122 stems from elevations between
2500
and
3500
ft . All figures are percentages
of tota l stenis in stat io n fro m 1-in. diameter class up.
Tree species
1 1
Ac er sp i c a tum . . . . . . . . . . . . 4
Frax inus ame r ic ana . . . . . . . .
2
Tilia heterophylla
. . . . . . . . . . .
17
Aesculus octandra
. . . . . . . . . .
7
Fagus grandi fo l ia
. . . . . . . . . . 1
Acer saccharum . . . . . . . . . . . .
6
Magno lia ac um ina ta . . . . . . .
x
Zlex opaca . . . . . . . . . . . . . . . . . .
Prunus se ro t ina
. . . . . . . . . . . . .
T suga c anade mis
. . . . . . . . . .
25
Betula allegheniensis . . . . . . . .
26
Lir iodendron tu l ip i fera
. . . . . .
2
Halesia monticola . . . . . . . . . . 5
Magnolia fraseri
. . . . . . . . . .
2
Acer pensy lvanicum
. . . . . . . 1
Betula lenta
. . . . . . . . . . . . . 2
Ac e r rubrum . . . . . . . . . . .
x
I l ex mon ta na . . . . . . . . . . . . . . .
Querc us borealis
v.
m a x i m a
. . .
Co rnu s flflorida . . . . . . . . . . . . . .
Hamame l i s v i rg in iana
. . . . . . . . .
Ostrya virginiana . . . . . . . . . . . . .
Carya glahra . . . . . . . . . . . .
Clrthra acvminata
. . . . . . . . . . . .
Ara l ia sp inosa . . . . . . . . . . . . . .
Carya tomentosa . . . . . . . . . . . . .
Pyrular ia pubera
. . . . . . . . . . . .
Amelanchier arborea . . . . . . . . . .
Castanea dentata
(dead*).
. . . . . .
Robinia pseudoacacia . . . . . . . . .
Oxydendrum arboreum . . . . . . . .
Quercus pr inus . . . . . . . . . . . . . .
Sassafras a lbidum . . . . . . . . . . . .
Nyss a sy lvat ica
. . . . . . . . . . . . . .
Quercus velutina . . . . . . . . . . . . . .
Quercus alba
. . . . . . . . . . . . . . . .
Quercus coccinea
. . . . . . . . . . . . .
P i n u s r i g i d a
. . . . . . . . . . . . . . . .
P i n u s p u n g e m . . . . . . . . . . . . . .
Percents
y
classes
RIesic.
. . . . . . . . . . . . . . . . . . . .
97
Submesic
. . . . . . . . . . . . . . . . . .
3
Subxeric
. . . . . . . . . . . . . . . . . . . .
Xeric.
. . . . . . . . . . . . . . . . . . . .
4
ree s in s t a t i o n s . .
. . .
33;
Site-samples used. . . . . . . . . . .
STATION U M B E R
2 / 3 ) 4 / 5
6 1
7 8 1 9 ~ l O I l l I l 2 I 1 3
59;
671
41; 518
62; 35; 3 T 42:
43; 41;
554
5
x, Present below
5 7
*Dead ch estnut trees were counted in all stands.
Since the smaller stems had ceased to be identifiable as such in 1947,th e number of chestnuts in t he tables is smaller
than the number of living stems would have been (see size distributions in Appendix C .
8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
9/81
R. H. WHITT KER
Ecological Monograph6
Vol. 2 6, No. 1
DISTRIBUTIONSF SPECIES
LOKG
THE quence of species populat ions along the moisture
MOISTUREGRADIENT
gradient is similar at all elevations below 4500 ft,
Distributions of tree populat ions along the mois-
but differs in deta il because of the varied relations of
ture gradient are shown in the three tables for dif-
species populations to elevation. From mesic sites to
ferent elevation belts (1500-2500 f t , Whi ttaker 1951, xeric, major tree species have their population
table 1 ; 2500-3500 and 3500-4500 ft , present work,
maxima in the sequence:
Aesculus oc ta l tdra*, T i l ia
tables 2 and 3). Almost all species show a rounded
he t e r ophy l l a , Be t u l a a l l eghen i ens i s
Britt.,
Hales ia
or bell-shaped curve of population distribution along
mont icola
(Rehd.) Sarg.,
Acer saccharurn , L i r ioden-
P o ~ u l ~ t i o nhe gradient (see Figs.
21
31 4) . curves
d r on tu l i pi fe r a, T s ug a ca na de m is , Q u e r c ~oreal is v.
for different species, including many of those in dif-
mazima( ~ ~ ~ ~ h . 1arya
glabra ,
ace,.
rubrum,
ferent
Car ya t om en t osa , Cas t a lz ea den t a ta , ue r c m prinus
centers for species and limits of their distributions
Nomenclature follows tha t of Fe rna ld
(1950)
except where
are well scattered along the gradient. The basic se-
.,thorities ar e given.
T BLE3. Composite transec t of moisture gradien t between 3500 an d 4500 ft , distri buti on of trees alon g gradi ent .
Transect along the moisture gradient from mesic valley sites (Sta.
1)
to xeric southwest slope sites (Sta. 12), based
on 46 site counts including 4906 stems from elevations between 3500 f t a nd 4500 ft .
All
figures are percentages of
total stems in station from 1-in.
diameter class up.
ST TION
NUMBER
Tree species
1 2 3 4 5 6 7 8 9 1 0 1 1 1 2
Fagus grandijolia. . . . . . . . . . . . . . . . . . 10 5
1
1
1
. . . .
. .
.
.
.
. . . .
Ilex opaca. . . . . . . . . . . . . . . . . . . . . . . . . .
1
. .
x
. . . . .
.
. . . .
. .
. .
. .
Picea Tubens. . . . . . . . . . . . . . . . . . . . . . . .
x . .
x
. . . .
. . .
. . . . . .
Cornus alternijolia. . . . . . . . . . . . . . . . .
1 1
. .
s
x
. . . .
. . . .
.
.
.
. .
Aesculusoctand~a. . . . . . . . . . . . . . . . .
8
9
2
6
1
. .
. .
. .
.
.
. .
. .
Tilia hete~ophylla.
. . . . . . . . . . . . . . . .
29
11
9
1
14 3 . .
. .
.
. .
. .
. .
Acer spicatum. . . . . . . . . . . . . . . . . . . . .
16
11
. .
17
1 . .
.
.
. .
.
.
.
. .
Acersaccharum . . . . . . . . . . . . . . . . . . . . 7
7
1 1 5
1
. .
. . . . .
. .
. .
Prunus se~otina. . . . . . . . . . . . . . . . . .
2
1
. .
1
x 2
. .
. . . .
. .
. .
. .
Fraxinus americana.. . . . . . . . . . . . . . .
1
1
. .
1
1 x
. .
.
. . . .
. .
Betula allegheniemis. . . . . . . . . . . . . . .
5 17 10 15
4
1 x
. .
. . . .
.
. .
Magnolia acuminala
. . . . . . . . . . . . . . . .
. . . .
x
. .
1
. .
. . . .
.
.
.
Magnolia jraseri.
. . . . . . . . . . . . . . . . . .
. . 20
4
1
. . 1 . . . . . .
.
.
.
Tsuga canadensis.. ............
20
22
34 62
18
x x
1
. .
. . . . . .
Halesia monticola.. . . . . . . . . . . . . . . . .
5 8 4
1 9 13 3
1
1
. .
. . .
Ilex montana..
. . . . . . . . . . . . . . . . . . .
1
x
. . 1
1
1
2
. .
.
. .
.
.
. .
Ace~pensylvanicum . . . . . . . . . . . . . . .
1 x 1
3
8 3
x 1
. .
. .
. .
.
.
Amelanchie~ aeciis. . . . . . . . . . . . . . . . . . .
x . . x
x
. . . . . . . . . . . . . .
Quercus borealis.
. . . . . . . . . . . . . . . . . . . .
1
. .
. .
2
40
10
4
15 11
2 1
Acer rubrum. . . . . . . . . . . . . . . . . . . . . . . .
1
. . . .
1
6 37
21 13
10
8
1
Prunus pensylvanica. . . . . . . . . . . . . . . . .
. .
2
. .
. . .
1 . .
. . . .
. . .
Betula lenta.. . . . . . . . . . . . . . . . . . . . . . .
.
.
1 4 4 1 2 2 . .
. .
. .
. .
Clethra acuminata..
. . . . . . . . . . . . . . . . . .
. . . .
1
x
. . . .
.
. . . .
.
. .
Hamamelis vi~giniana
. . . . . . . . . . . . . . .
. . . . . .
2
5
17 7 1 . .
2
. .
Cornus jiorida. . . . . . . . . . . . . . . . . . . . . . .
. . . .
. .
1
. .
x 4
. . . .
. .
. .
Li~iodendron ulipijera. . . . . . . . . . . . . . .
. . . . . .
2
. . . .
1
x
. . .
Rhododendron calendulaceum
. . . . . . . . . .
. .
.
. .
.
. .
1
. .
1 4
. .
.
.
. .
C a ~ y alabra . . . . . . . . . . . . . . . . . . . . . . . .
. . . .
.
.
. . 4
x 2
6 5
. . .
Ca~yaomentosa.. . . . . . . . . . . . . . . . . . . .
. . . . . .
. .
. .
. .
2
. .
. . . .
.
.
Carya ovalis.. . . . . . . . . . . . . . . . . . . . . . . .
. . . .
. .
. . . . .-
x
. . . .
. .
Nyssa sylvatica.
. . . . . . . . . . . . . . . . . . . . .
.
.
1
. .
. . . .
2
4
1
2
7
. .
Oxydend~umarboreum.. . . . . . . . . . . . . . .
. .
x
1
. .
1 3
8 1 4 1 6
1 1
Cmtanea dentata (dead).
. . . . . . . . . . . . .
. . . . . .
2
5
7 9 10
12
1
. .
Sassaj~as lbidum... . . . . . . . . . . . . . . . . .
. . . . .
. .
1 1 1 1 4 x . .
Quercus alba. . . . . . . . . . . . . . . . . . . . . . .
. . . . .
.
. .
2
1 8
24
10
x
. .
Rolrinia pseudoacacia.
. . . . . . . . . . . . . . . .
. . . . . .
. . 4 5 1 3 8 3 x
Quercus prinus. . . . . . . . . . . . . . . . . . . . . .
. . . . . .
. . 3 4 15
4
16
11
1
Quercus velutina. . . . . . . . . . . . . . . . . . . . .
.
. .
.
. .
. .
. . x x l l . .
. .
Quercus coccinea..
. . . . . . . . . . . . . . . . . . .
. . . . . .
. . . .
1
. .
. . . .
.
.
1
Pinus rigida.
. . . . . . . . . . . . . . . . . . . . . . .
. . . . . .
. .
. .
. .
7
1 1
11
46
Pinus pungem. . . . . . . . . . . . . . . . . . . . . .
. .
. .
. . . .
. .
. .
1
4
54
49
Percents by classes
hfesic . . . . . . . . . . . . . . . . . . . . . . . . . . .
98
98 95
90
78 22
5
3
1
. .
. . . .
Submesic . . . . . . . . . . . . . . . . . . . . . . . . .
2 2 4
9
19 62 70
44
39 26
12 2
Subxeric . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. . 1
1
2
16 23
46
58
69
23 2
Xeric.
. . . . . . . . . . . . . . . . . . . . . . . . . . . . .
. .
.
. .
. . . .
1
7 2
5
65
96
Treesinstations
. . . . . . . . . . . . . . . . . .
377
597 520
232
449
594
472 266 369 378
297 355
Site-samples used. . . . . . . . . . . . . . . . . .
1
7
4
4
4
4
4 4
3 4
4
x
Present
below .5 .
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F I G . 2.
Transect of the moisture gradient, 1500 2500
ft . Topcurves for tree classes: a, mesic; b, submesic.
c
subxeric; d,
xeric. Middle-curves f o r t ree
a
~ ~al legheniensis; ~
b,
cornus
c uercus for*;
prinus
d, Pinus virginiana,
Bottom-curres for
under.
growth coverages a, herbs
;
b, shrubs.
Q uercus a l ba , Q . ve lu t ina , Q coccinea,
and
Panus
v i rg i n i ana , P . pungens ,
and
P . r i g i da .
Comparable data on population levels are not
available for shrubs and herbs, but these appear to
be distributed in the same manner as the trees. Spe-
cies populations overlap widely along the gradient,
and centers and limits of distribution are scattered
along the whole of the gradient.
Anlong the shrubs
R h o d o d e n d r o n m a x i m u m
is the
most important specic3s in mesic sites, but it is a
major species in submesic sites also and occurs in
subxeric and some xeric ones.
H y d r a n g e a a r b o -
rescens is the only other shrub species very widely
distributed through mesic and submesic forests.
Lezicothoe ed i torum
occurs only locally in mesic for-
ests; other mesic shrub species are restricted to low
elevations or high ones. I n submesic sites a number
of deciduous species make up the shrub stratum along
with the evergreen ericads
R h o d o d e n d r o n m a s i m u m
and
K al m i a l a t i f o l i a .
Among the major species of
submesic shrubs some
V i b u r n u m a c e r i fo l iu m , C a l y -
can t hus f e r t i l l s , P yru l ar i a pubera )
extend more
widely into mesic sites, but these and others
G a y -
lussac ia urs ina
(M. A. Curt is) T. G.,
C l e t hra acu -
m i n a t a , R h o d o d e n d r o n c a le n d u la c e u m , S m i l a s r o t u n d i -
f o l i a )
extend varying distances into subxeric and
xeric sites. I n subxeric sites and some xeric ones,
Kalmia la t i fo l ia
is the principal shrub species.
L y -
o n ia l i g u s t r i m , S m i l a x g la u ca ,
and the widespread
species V a c c i n i u m c o n s ta b l ae i A. Gray may best be
grouped with it in a subxeric class. Several shrub
species
V a c c i n i u m v a ci ll an s, V . h i r s u t u m
Buckl.,
V .
s tamineum, Gaylussac ia baccata , P ier i s j l or ibunda,
Z l ex m on t ana
v.
beadlei
(Ashe) Fern.) are centered
in xeric sites and extend varying distances into sub-
xeric and snbmesic ones.
A
number of herb species are centered in mesic
forests and dominate the herb stratum there; major
IG
3.
Transect of the moisture gradient,
2500 3500
f t .
for
tree ,%lasses: , mesic; b, submesic;
c, subxeric; d, xeric. Middle-curves for tree species:
a,
Ha esi m ont t coza ;
b,
A c e r r u b l u m ;
c,
Quercus cot
Ctnea
d,
Pinus rigida.
Bottom-curves for undergrowth
coverages: a, herbs; b, shrubs.
species include
Dryopteras sp inulosa
v.
i n t e rm ed i a ,
d t h y r t t t n ~ t hel ypt e raoades , C au l op l ry ll um t hal ic -
t ro i des , C i m ica fuga racem osa , E up a t or i um rug osu m ,
Lrrpor tea canade ns i s , Imp at i e ns pallada,
and
A s t e r
di rar i ca tus .
These extend varying distances into sub-
mesic forests. Other species which are important in
mesic sites
S m i l a n n a r a c e m o s a , P o l y g o n a t u m
spp.,
Desnlodanm nudaf lorztm, Polystachum acrost ichoides)
are major herb species also in submesic sites.
The
latter have been grouped with those mcre clearly
centergd in submesic sites A u r e o l a r i a l a e v i g a t a
(Raf.) Raf.,
Prenan thes t r i fo l io la ta , Medeola v i r -
g i n i ana , D ryop t e r i s noveboracensi s , V er a t r um parr i-
f iorum
Michx.) into a submesic class. A number of
these species extend widely into subxeric sites, where
they are joined by others
C a m p a n u l a d i v a r i c a t a ,
C h i m a p h i l a m a c u l a t a )
of more limited extent into
submesic sites.
G a l a s a p h y l l a ,
the most important
subxeric herb species, is widely distributed from sub-
mesic sites to most xeric ones. Other herb species are
centered in xeric sites; most of these
P t e r i d i u m
aqzl i l inum
v.
l a t i u scu l um , Tephros i a v i rg i n i ana , B ap-
t i s ia t i nc to r i a , G au l t he r i a p rocum bens ) extend widely
into subxeric sites, and some of them
E p i g a e a r e p -
e n s , P a n i c u m
sp.,
C o r e o p s i s m a j o r , A n d r o p o g o n s c o -
p a r i u s )
extend into submesic sites, in part of their
elevation range, a t least. More complete lists of herb
and shrub species assigned to moisture classes are
given in the Summary of Distributional Groupings.
There is no point along the gradient at which
either floristic composition or dominance changes
abruptl y in any stratum. Rather than this, the
rounded and tapered distributions of species popula-
tions, the scattering of their distributional centers
and limits along the gradient, and their broad over-
lap with one another imply gradual and progressive
change in relative importance of species and in total
floristic composition from one extreme of the gradi-
ent to the other.
8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
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FIG.
4.
Transect of the moisture gradient, 3500-4500
f
t
Top-curves for tree classes a, mesic;
b
submesic;
c, subxeric; d, xeric. Note expansion of mesic stands,
compared with Figs. 2 and 3 Middle--curves for tree
species: a, Tilia heterophylla; b, Halesia mnt ico la (both
the preceding are bimodal, with populations on each
side of the mode of Tsuga)
c, Tsuga canadensis; d,
Querms alba; e, Pinus pungens. Bottom-curves for
undergrowth coverages: a, herbs; b, shrubs.
Various trends in community composition and
structure can be followed from one extreme of the
moisture grad ient to the other. These trends, com-
parable to those already studied in foliage insect
communities (Whittaker 19.52), are in most cases
continuous through whatever community-types or
associations may be recognized.
GROWTH - F O RMS
Four growth-forms of trees are recognized in the
Smokies (see Pa rt 111) pines, abietines (Tsziga
canadensis), oaks, and other deciduous trees. A con-
tinuous shift in proportions of these appears along
the moisture gradient (Whitt aker 1953 :49 ). De-
ciduous trees other than oaks predominate in mesic
sites, oaks in intermediate sites, and pines in xeric
sites. Toward higher elevations a belt in which
Tsuga canadensis is dominant is interposed between
the first two of these. The pa tte rn of growth-form
composition, and the predominance of the semi-sclero-
phyllous, deciduous oak grouping in intermediate
sites, is the same whether or not Castanea dentata ,
Fagus grandzfolia, and the ericaceous tree Oxyden-
drzcm arboreum are grouped with the oaks. Among
the shrubs a comparable shift in growth-form com-
position appears, involving deciduous and evergreen,
ericaceous and non-ericaceous species. Deciduous
non-ericaceous species predominate in mesic sites,
with some exceptions; but deciduous species decline
in importance along the gradient as evergreen eri-
cads increase to become strongly predominant in sub-
xeric sites. Toward the xeric extreme, evergreen
ericads decline and deciduous ericads (Vaccinioideae
or Vacciniaceae) increase to dominate the shrub
stratum in most xeric pine heaths.
HITTAKER
Ecological Monographs
Vol. 26 No.
Herb species are less easily classified, but trends in
importance map be observed among the more numer-
ous growth-forms which might be recognized. Fer ns
with delicate foliage (Dryopteris and Athyrium) are
centered in mesic sites and decline in importance
through submesic into subxeric ones. A group of
herbs of moderate stature with broad, thin leaves and
a characteristic spreading or umbrella-shaped growth-
form (Caulophyllum, Cimicifuga, Actaea, Impatiens,
Trillium, Laportea, Osmorhiza, Thalictrum, Eupa-
torium rugosum, Aster divaricatus) prevail along
with ferns in mesic sites and are of decreasing im-
portance toward more xeric ones. Other herb form s
-rosette plants (Goodyera pubescens, Verat rum
parviflorum, Viola hastata) and those with leaves
spaced along the qtem (Aureolaria, Solidago, Smila-
cina, Vvularia, Melampyrum, Coreopsis)-are more
important in submesic and subxeric sites; and foliage
of herbs in these sites is, on the whole, tougher than
that of the delicate-leaved mesic herbs.
Species of
these groups occur also in xeric sites, but
a
variety
of other herb types prevail there: grasses (Andro-
pogon, Pan icum), ground heaths Gaultheria,
Epigaea), legumes (Baptisia, Tephrosia), a tough-
leaved fern (Pteridium), and a club-moss (Lycopo-
dium obscurum). Of these the grasses are the major
herb growth-form in xeric sites at lower elevations;
and the ground heaths are the major herb growth-
form in subxeric sites and in xeric ones at higher
elerations.
COVERAGES
I n general, tree coverage and density of the canopy
decrease along the moisture gradient from cove for-
ests into pine forests; light penetration to lower
strata consequently increases along the gradient
(TIThittaker1952). Estimated tree coverages increase,
however, from subxeric sites (oak-chestnut heath)
into xeric ones; the very low canopy coverage in oak-
chestnut heath is in part a consequence of death of
the chestnuts. Shrub coverage in general increases
along the gradient toward more xeric sites (Figs. 2,
3, 4 ) . This trend is modified, however, by the pres-
ence of a secondary maximum of shru b coverage in
hemlock fores ts in-mesic sites, and by a final decrease
of s hrub coverage in most xeric sites. He rb coverage
in general decreases along the gradient from mesic to
xeric sites. This trend also is modified in two re-
spects-by very low coverages in hemlock stands, and
by a final increase of herb coverage from subxeric
sites into xeric ones. Maximum herb coverages occur
in mesic deciduous forests, where moisture conditions
are most favorable, and in xeric pine forests, where
light penetration to the herb level is greatest. He rb
and shrub coverages show a clear inverse relation
within the set of transects for elevations below 4400
f t in the Great Smoky Mountains (Figs . 2 3, 4) .
D IVERS I T I E S
Diversity of the tree stratum can best be ap-
proached through the alplta values of Fisher (Fisher
r t al. 1943 Williams 1947, 19.50 Whi ttaker 1952).
8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
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January 9 5 6
VEGETATION THE GRE
F
These values provide a measurement of richness in
species which is, within limits, independent of
sample size. I n Fig. 5 alpha values fo r composite
stand counts are plotted on the vegetation pattern for
the Smokies developed in Part
111 At all elevations
highest diversity values are in intermediate sites-in
the cove forest transition below 3000 f t and oak-
chestnut forests above 3000 ft . The hemlock stands,
which provide exceptions to all the trends discussed,
are less diverse than the more and less mesic stands
on each side of them. I n general, however, species
diversity of the tree stratum rises along the gradient
from one minimum in most mesic sites to a maximum
in submesic sites and declines to a second minimum in
xeric sites.
FIG 5 Pa t te rn of t re e species d iversi ties (alpha d i-
ve r s ity va lues , f o r a l l t r ee s t em s in the compos i te s t a nd
counts of A ppendix C .
Alpha values cannot be computed for the under-
growth data available. Analysis of the transects
through average numbers of species listed per sample
provides a more limited indication of diversity trends
in the herb and shrub strata . F or shrubs the average
numbers of species recorded in mesic, submesic, sub-
xeric, and xeric stands are : 5.2, 7.6, 6.2, 6.6. A sub-
mesic maximum corresponding to that for trees is
thus suggested; but the shrub stratum in xeric sites
may be more diverse than that in
subxeric ones, often
strongly dominated by Kalmia latifolia. Correspond-
ing average numbers of herb species ar e : 19.1, 10.6,
7.1, 8.6. The herb stratum is thus richest in species,
as well as of highest coverage, in mesic sites and
shows a secondary maximum of both diversity and
coverage in xeric sites.
SIZES 4 N D
XI-MDERS
O F
STEMS
O F
TREES
Stature and stem diameter of canopy trees in gen-
eral decrease along the moisture gradient . I n mesic
sites canopy trees are more than 100 f t high and 3-4
f t or more in diameter, in xeric sites they ar e mostly
50-75 f t high and 1.0 to l..5 f t in diameter The num-
ber of tree stems per unit area In general increases
along the gradient (c f. Ilvessalo 1921, Lutz 1932 ),
in inverse relation to tree stature. The cove forests
have mostly between 7.50 and 1000 stems per hectare
from the 1-in. class up (except in stands of higher
elevations where there are many small stems of Acer
spicatum) the more xeric stands have mostly 2000
to 2500 stems per hectare. I n pa rt the increase in
stem numbers toward xeric sites reflects the smaller
sta ture and denser growth of canopy trees; but the
numerous small stems in more xeric sites are pre-
dominantly made up of small-tree species. These
small-tree species (Carpinus carol~nlana,Magnolia
trzpetnla, Ostrya vi rg~n lana , Il ez opaca; Cornzis
jlortdn, Betzcla lenta, Acer r~lbr~lm,Hamamelis vlr-
giniamn, Cletltra aczcminata, Acer pensylvaniczcm;
Robinia pseudoacacia, Oxydendr~lmarboreum, Sassa-
fras albiclzcm; Q~lerczcsmarilandica) are relatively un-
important in most mesic sites ( as low as 1-2 of
stems in some cove forests) and most xeric sites
(10 -15 ). I n submesic and subxeric stands of lower
and middle elevations, however, the small-tree species
comprise around 50 of stem numbers.
Trends in stand composition have been much af-
fected by death of the chestnuts (Castanea dentata).
In many submesic and subxeric stands chestnut
formed 30-60 of the canopy stems, and death of the
chestnuts both removed many of the larqest stems
from the stand and permitted heavy reproduction of
other species. Effects of death of the chestnuts are
most evident in chestnut oak-chestnut forests, in
which maxirriunl numbers of tree stenis per unit area
now occur, and in which 70 of the s t e r ~ ~ sn sollie
stands are now of the sniall-tree species.
Trends in tree sizes are illustrated in a family of
curves (F ig . 6) , in which steepness of slope reflects
normal survival of small trees into larger size classes.
The more xeric the site, the steeper the curve and
the smaller the proportion of growth and survival
into larger size classes. The oak-chestnut curve is
altered by death of the chestnuts and increased re-
production of other species; the dotted curve is an
interpolation of what might be expected otherwise.
The hemlock forests are exceptional, for large sizes
are even more heavily represented than in cove hard-
woods forests. Fi g. 7 indicates the effect of the same
gradient on growth and survival in the populations of
red maples (Acer rubrum).
Curves such as those illustrated in Figs. 6 and 7
ore expressions of the dynamics of stands, the man-
ner in which the tree population is maintaining it-
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HITTAKER
Ecological Monographs
Vol.
26 No.
1
FIG.
6.
Stem number-diameter curves for tree stands
at middle elevations.
self o r failing to do so (Paczoski 1928, Meyer
Stevenson 1943). Meyer Stevenson (1943) have
indicated a relatively simvle relation of diameter and
.
stem number, which plots as a straight line on a log
and linear graph like those of Figs. 6
7.
Such a
plot implies that growth rate and survival rate are
largely constant with age; variation of growth rate
with age introduces into log-linear plots the curva-
ture to be observed in Figs.
6
7.
A curve following
the stand data more closely has been developed. As-
suming x = arw to be a fit for the stem number-age
relation, and
w
= ( y d ) C reasonable approxima-
tion for the age-diameter relation, then the stem
number-diameter relation becomes x
=
ar(y
I n this is the number of stems in a diameter class,
a
is the number of stems in the initial class,
r
is the
survival ratio between successive classes,
y
is the
middle diameter of the class, and d and c are con-
stants relating diameter to age. (A n alternative,
purely empirical form which is less difficult to apply
is the series a, ar, ar (r -b ), ar (r -b ) (r-2b) . . .
,
in which
b
is arbitrarily introduced to help the curve
fit.)
The value of such curves is in the possibility of
recognizing the self-maintaining, climax condition
they describe. Many all-age and probably climax
stands which have been analyzed show the basic form
illustrated. I t is also true tha t the continuous repro-
F IG 7
Stem number-diameter curves for
Boer ru
r m in different sites.
duction and replacement which these curves imply
is by no means the only way climax stands can main-
tain themselves (Jones 1945, Whit taker 1953). Cyclic
reproduction seems to occur in the Smokies pine
stands ( Pa rt 111). Other coniferous stands are stag-
nant in the sense that stems are concentrated in
large r size-classes, with inadequate numbers of smaller
stems to replace them if a constant survival ratio
is assumed. Some of the stands more strongly domi-
nated by
Tsuga canadens i s
are of this form (cf.
Meyer Stevenson 1943), as ar e some of those of
the spruce-fir forests, especially the high-elevation
stands of
Abies fraseri .
I t seems likely that repro-
duction in these stands is periodic, partial or com-
plete destruction of the canopy permitting its re-
placement at irregular intervals, rather than con-
tinuously. If such limitations are kept in mind, hon -
ever, analysis of all-age stand composition may con-
tribute to the difficult problems of climax identifi-
cation.
The basic similarity of the curves for different
parts of the gradient may be observed in Fig. 6
Curves for individual tree species differ widely in
slope from those fo r whole stands, but Fig. (and
the stand data for other species, Appendix C) indi-
cate the same basic similarity. Ap ar t from certain
distortions of the curves clearly produced by death
of the chestnuts, there is no evidence that any of
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13
anuary, 1956 VEGETATION
TFIE
GREATS M O K YF MOUNTAINS
these undisturbed stands are changing toward other
types. All, from cove forest to pine forest, have the
self-maintaining properties of climax stands, so far
as can be determined. Evidence of convergence to-
ward a single climatic climax type is thus lacking.
I n the southwestern Smokies, outside the range of
spruce-fir forests, deciduous forest types extend to
the highest peaks (around
5500
ft or
1680
m). In
order to study the distributions of p lant s in these
deciduous forests above
4500
f t, a transect by site
was arranged for 37 site-samples. The most mesic
sites available at these elevations are gaps and con-
cave slopes of north and northeast exposure, where
forests of
Fagzcs gralzdifolia
mixed with other mesic
trees occur. The south, southwest, and west exposures
TABLE
4.
High-elevation deciduous forests, transect
of exposure gradient by topographic sites for Eastern
Forest System types above
4500
ft. Distributions of
trees by percentages of stems in stand.
Steps in gradi-
ent:
1
beech-mixed forests in sheltered north slopes;
2, gray beech forests in sheltered south slopes;
3,
red
oak-chestnut forests, open slopes;
4,
white oak-chestnut
forests, open south slopes;
5
grassy balds on exposed
peaks.
Acer spicatum. . . . . . . . . . . . . 14
Aesculus octandra.
. . . . . . . . . .
11
Betula allegheniensis.
. . . . . . .
10
Acer pemylvanicum. . . . . . . . . . 1
Acer saccharum.
. . . . . . . . . . . .
1
Tili a heterophylla.
. . . . . . . . . .
x
Sorbus americana. . . . . . . . . . .
x
Cornus alternifolia. . . . . . . . . . . x
Fraxinus americana.
. . . . . . . .
x
Amelanchier laevis . . . . . . . . . . .
4
Fagus gandifolia. . . . . . . . . . . 50
Zlez montana. . . . . . . . . . . . . . . . .
Prunus serotina.. . . . . .
Halesia monticola. . . . . . . . . . . 2
Quercus borealis..
2
Tsuga canadensis.. . . . . . . . . . . 1
Acer rubrum..
. . . . . . . . . . . . . .
2
Hamam elis wirginiana.. . . . . . . . .
Betula lenta. . . . . . . . . . . . . . . . .
Vaccinium constablaei. . . . . . . . . .
Rhododendron calendulaceum.
Magnolia fraseri. . . . . . . . . . . . . .
Magnolia acuminata.. . . . . . . . . .
Ozydendrum arboreum.
Castanea dentata
(dead).:
1
Sassafras albidum. . . . . . . . . . . . .
Quercus alba..
. . . . . . . . . . . . . . . .
Robinia pseudoacacia. . . . . . . . . .
Nyssa sylvatica.
. . . . . . . . . . . . . .
Quercu.7 velutina. . . . . . . . . . . . . . .
Prunus pemylvanicn.. . . . . . . . . .
Pinus pungem.
. . . . . . . . . . . . . . .
Pinus rigida.
. . . . . . . . . . . . . . . . .
Pinus strobus..
. . . . . . . . . . . . . . .
Liriodendron tulipifera .,
. , . . . . .
Total stems. . . . . . . . . . . . . . . .
Site-samples used.
. . . . . . . . . .
x present below
0.5%.
- seedling^ recorded.
are more xeric; and these may be grouped into three
stages: sheltered south slopes and south-facing sides
of gaps, supporting beech forests; more xeric open
slopes supporting red oak-chestnut forests, and most
xeric open south- and southwest-facing slopes, sup-
porting red and white oak-chestnut or white oak-
chestnut. Some most exposed summits of peaks,
fi-
nally, are covered by grassy balds. Distributions of
tree species may be observed along this five-stage
transect (Table
4
; distributions of shrub and herb
species are not published here (see Note on Supple-
mentary Publication).
Relations of tree species to the moisture gradient
are in general the same at high elevations as at low
ones. Hales ia mont ico la , however, which is a highly
mesic canopy tree at lower elevations is a submesic
small-tree species at these highest elevations ; this
species comprises two population-types with separate
distributional centers (see Part
I1
and Appendix
A) .
V i b u r n u m a l n i f o l i u m , C o r n u s a l te r n if o li a , and H y -
drangea arborescens are major shrub species at the
mesic extreme, V a c c i n i u m c o n s t a b l a e i and R h o d o -
d e n d r o n c a l e n d u la c e u m in the oak-chestnut forests.
V a c c in i u m c o n sta b la e i
spans the whole of the gradi-
ent from north-slope beech stands to grassy balds, as
do the less frequent species
R ib e s r o tu 7 td i f o l i u m
and
R h o d o d e n d r o n c a ta wb ie n s e . Those shrub species
( K a l m ia l at i f o li a , L y o n ia l i g u s tr i n a , G a y lu s s a c ia ba c-
c a t a, V a c c i n i u m va c il la n s, V . h i r s u t u m ) which are
most abundant in the forest-heath types at lower ele-
vations are limited to the oak-chestnut forests and
grassy balds in the transect.
A r o n ia m e la n o c a r p a
(Michx.) Ell. and V i b u r n u m c a s s i n o i d e s , species
which occur in the heath balds, were recorded in the
transect only from the grassy balds.
At the mesic extreme, species of the mesic and high-
elevation mesic herb groupings dominate the herb
stratum; some of these species extend into south-
slope beech stands and red oak-chestnut s~ands.
Ca r e s a e s t i v a l i s is strongly dominant in south-slope
beech stands and extends into both more mesic north-
slope beech stands and less mesic red oak-chestnut
forests.
A t h y r i u m J i l i x - f e m i n a
v.
asplel t io ides
is a
major herb species of these high-elevation forests and
extends along the gradient from not-th-slope beech
stands to white oak-chestnut, as does M e d e o la v i r -
g in ia n a . E p ig a e a r e p e n s , G a la x a p h y l l a , P e d ic u la r i s
c a l z a d e n s i s , P t e r id iu m a q u i l i n u m v. l a t i u s c u l u m , and
Ca m p a n u la d i v a r i c a ta ,
species of more xeric forest
types a t lower elevations, ar e limited to the oak-chest-
nut s tands in the high-elevation transect. Ecotypic
populations of some forest herb species
( A n g e l i c a t r i -
q u in a ta , S t e ll a r ia p u b e r a , R u d b e c k ia lm n ia t a , P r e -
n a n th e s a l t i s s im a , H o u s to n ia s e r p y l l i f o l i a , G e n t ia n a
d e c o r a )
occur in the grassy balds with a variety of
other species (see Part 111).
Carex aes t iva l i s
and
other species centered in the south-slope beech stands
and red oak-chestnut forests above
4500
f t have been
grouped in a high-elevation submesic herb union.
Stratal trends are less clear-cut in these forests
than in those of lower elevations. Tree-stratum di-
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15/81
E c o l o g i c a l M o n o g r a p h s
V o l .
26,
N o . 1
versity decreases from north-slope beech stands into
T LE . Composite elevation transect in mesic sites,
south-slope ones, increases from these to a maximum
distribution of trees. All figures are percentages of total
in red oak-chestnut forests, and decreases again into
white oak-chestnut. Coverage of the shrub stratu m
Station I*
decreases from north-slope into south-slope beech
Elevation,hundredfeet. 6
)
stands, increases through red oak-chestnut to white
Tree species
oak-chestnut stands and the forest-edge of grassy
Fagus grand tfolia..
. . . .
6
balds, and is low in the grassy balds. He rb coverage
Tsuga mnadensis. .
. . .
12
Halesia mont~cola . . . . . .
3
increases from the north-slope to the south-slope
Prazznus amerimna..
. .
x
beech stands, is lower in the oak-chestnut forests, and
Till o heterophylla..
. . . . .
6
is near
100%
in the grassy balds.
As in forests of
Lzriodendron tuli pifer a. .
1
lower elevations, herb and shrub
coverages are in-
Aesculus octandra
. . . . .
4
Betula ollegheniensis.
. . .
1
versely related. Deciduous trees other than oaks de-
l c e r sae c hrum .
. . . . . . .
4
erease from mesic sites into submesic and subxeric
Magnolza fra seri. . . . . . . 2
ones, where oaks predominate; evergreen tree species
Magnolia tripetola .. . . . 1
are almost absent from these forests. I n the shrub
Magnolia acuminata. . . . . .
Carptnus carolzniana.. 10
stems in station from I-in. diameter class up.
5
20
24
28 32
36
40 44
1
7 8
.
x 1 2 ' 6 1 6
14
23 10
8
8
5
12 13
18 30 4
1
2 2 1 6 1 1
3 15
15 20 22
4
2 4 1 x x . .
4 2
5 4 1 1 1 4
5
16 11
8
10
4
2 1 2
5 1 2
4
3 5 2 x . .
x
1 . . . . . . . .
1 . . x
1
1
. .
. . . . . . . . . .
x
3
. . . . . . .
. . . .
1 x
x
.
.
4
. . . . .
.
~ 1 4 1 7 3
. . . . .
x
1
1
. . . . . .
1
. . . . . . . . .
1
13 2
. .
x
. .
3 2 1 1 2 5
1 x 1
. . . : . .
2 3 5 2 x 2
6 2 6 2 1 2
1 0 3 2 1 2 1
. . x x
2
x
5 1 1
. . . .
X . . X . . . . . .
. . . . . . . . . .
3 1 1 . . x .
X
. . . . . . . .
2 . . 1 3 1 1
. . . . . . . . . . . .
4 1
x . . x .
X
. . . . . . . .
. . . . . . . . .
1 x x
. . . . . .
48
52 56
1
10
I
0
. . . . . . . . . . . . . .
stratum non-ericaceous, deciduous shrubs prevail in
lnesic sites; but deciduous ericads (Rhododendron
calendulaceum and Vaccinium constablaei) prevail
in the oak-chestnut forests.
DISTRIBUTIONSSPECIES TO ELEVATIONF IN RELATION
MESIC
SITES
Progressive change in composition of cove forests
is indicated in the elevation transect of mesic sites
(Table 5, Fig.
8 ) .
Species distributions show a
rounded or bell-shaped form in most cases, overlap
broadly, and have their centers and limits scattered
along the gradient. Most major tree species occur
throughout the elevations represented in the transect,
but the sequence of their population centers from
lolv elevations to high is : Fagus grandifolia ("white"
population see Part 11 , Liriodendron tulipifera,
15
2d00
2&0 3 b
35b
4d00 45b
5000
EL EVA T ION IN F EE T
FIG. 8. Elevation transect in mesic sites, smoothed
curves for tree species: a, Liriodendron tulipifera ; b,
Tsuga canadensis c. Halesia monticola d, Tilia hetero-
p h y l l a ; e, Acer saccharum; f , Acer spicatum; g, Car-
pinus caroliniana h, Betula allegheniensis; i, Aesct~lus
octandra; j, B'raAinus americana; k, white, 1, red, and
m, gray populations of Fagus grandifolia (based on
data for 200-foot intervals).
I le z opc a
. . . . . .
1
Carua eordifmmu
. . . . .
2
Cladrastis lu teo.
. . . . . . . .
Acer spimtum.
. . . . . . . . . . .
Prunus se~ottna
. . .
Amelanchter laenis.
. . . .
Cmnus al lernifo lb. .
. . .
C m n u s f l m i d o . .
. . . . . . . .
14
Quercus bmealts &
v .
mazima
. . . . . . . .
3
Amelanchter arborea.
x
BeluIa lenlc
. . . . . . . . .
8
Acei pensgdnanicum. . . . 1
Acer rubrum . . . . . .
12
Ilez montona. . . . . . . . . . x
Carua glabra..
. . . . . . . . .
2
Carua lomento sa.. . . . . . . . .
Carua ooalts. . . . . . . . . x
Q u e r u s p r i n w .
. . . . . .
2
Nussa sulwrlim
. . . . . . .
1
Casfunea denlato (dead). 1
Que rc us a l h . .
. . . . . . . .
1
Oz~ae ndrum rbm e um . . 2
Pinus s f robus . . . . . . . .
x
S as sa fr as a b d u m . . . . . . x
Robinia pseudoacucia
. . . . .
Total stems. .
. . . . . . . . R
841 518 639 793 429 358 468 646 360 406
S i t e . ~ m ~ l ~ u ~ e d . . 2 5 5 2. . I
I
I I I I I I I I I I
*Stations grouped
t
400-it. intervals (1450-1800 it.. 1850-2200 it., etc.)
x. Present below 0.5%.
Betula allegheniensis, Halesia monticola, Acer sac-
charztm, Tilia heterophylla, Aesculus octandra, and
Faglis grandifolia ("red" and ((gray" populations).
The decline towad higher elevations of Tsuga cana-
densis and Magnolia fraseri does not reflect their
true distributions (cf. Appendix A) , for toward
higher elevations these species are increasingly segre-
gated into hemlock stands which were not included in
the transect. The most significant change in composi-
tion of stands occurs at 45 f t ; a t this elevation
there is a relatively abrupt shift of dominance from
other cove-forest species to gray beech (Fagus
grandifol ia). Some small-tree populations (Acer
spicatctm and Amelnnchier laez'is) are centered near
45 f t along with Aesculzis octandra and one popu-
lation of yellow birches (Betula allegheniensis or B.
Ititen). Trees and shrubs centered in the transition
from core forests to gray beech and spruce-fir forests
Sorbus america na. . . . . . . . . .
8/9/2019 Whittaker - Vegetation of the Great Smoky Mountains
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January. 1956 VEGET TION
THE
GREAT
SMOKY I5
F MOUNTAINS
fo r m the ecotona l -mes ic un ion l i s ted in the Sum -
ma ry o f Dis t r ibu t iona l Group ings .
Among the mes ic sh rubs two spec ies ( E u o n y m u s
a m er i ca n u s
a n d
L i n d e r a b e n z o i n )
a r e r e s t r i c t e d t o
lowest e levat ions; cer ta in others (C o rn u s a l t e rn i fo l i a
a n d
V i b u r n u m a l n if o li u m )
a r e c e n t e r e d a r o u n d
4500
f t a n d f o r m p a r t o f t h e e co to n al -m e si c g r o u p i n g .
R h o d o d e n d r o n m a x i m u m a n d Leucotho6 ed i torum
o c c u r a t a l l e l e v a t i o n s u p t o a b o u t 4500 f t ; H y -
drangea arborescens
occurs f rom some of the lowest
elevat ions to the highest recorded in mesic deciduous
f o r e s t s
( 5 5 0 0
f t ) . X o r e l a t i v e l y a b r