Associated Forest Cover
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Fraser magnolia is a moderately frequent tree species in a number
of forest types; however, its relative density is generally less
than 10 percent, regardless of its size or location (3,7,8). For
example, it constitutes only 0.3 percent of all trees on the
Jefferson National Forest in western Virginia.
At elevations greater than 1200 m (3,940 ft) associated species
include mountain maple (Acer spicatum), striped
maple (A. pensyluanicum), and sugar maple,
American beech, American basswood (Tilia americana), Carolina
basswood, yellow buckeye, yellow birch (Betula
alleghaniensis), and eastern hophornbeam (Ostrya
virginiana) (2,3,4,6,8). Elsewhere, commonly associated
species are: sweet birch (Betula lenta), hickories (Carya
spp.), American chestnut (Castanea dentata) (as
sprouts), flowering dogwood (Cornus florida), white ash
(Fraxinus americana), Carolina silverbell (Halesia
carolina), American holly (Ilex opaca), butternut
(Juglans cinerea), black walnut (J. nigra),
yellow-poplar (Liriodendron tulipifera), cucumbertree
(Magnolia acuminata), blackgum (Nyssa sylvatica),
sourwood (Oxydendrum arboreum), black cherry (Prunus
serotina), white, scarlet, chestnut, and northern red oaks
(Quercus alba, Q. coccinea, Q. prinus, and Q. rubra,
respectively), black locust (Robinia pseudoacacia), white
basswood (Tilia heterophylla), and eastern hemlock (Tsuga
canadensis) (14,15). Eastern white pine (Pinus strobus),
pitch pine (P. rigida), Table Mountain pine
(P. pungens), and shortleaf pine (P echinata)
are occasional associates.
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Climate
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Within the natural range of Fraser magnolia during the growing
season, average rainfall varies considerably. In West Virginia,
April to September rainfall averages 610 to 760 mm (24 to 30 in),
but in north Georgia and western North Carolina, it averages 910
to 990 mm (36 to 39 in) (17). Total annual precipitation in West
Virginia varies from 1020 to 1270 mm (40 to 50 in), while in the
southern Appalachians, the variation is between 1020 and 2030 mm
(40 to 80 in).
July temperatures average 21° to 24° C (70° to 75°
F) and January temperatures range from -1 to 2° C (30°
to 35° F) where Fraser magnolia occurs in West Virginia and
Virginia, and from 2° to 4° C (35° to 40° F)
in the southern end of the Appalachians. The frost-free period
varies from 150 to 170 days in West Virginia and Virginia, and
from 170 to 180 days in the southern Appalachians of eastern
Tennessee and western North Carolina.
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Damaging Agents
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Because of its thin bark, Fraser magnolia
is very susceptible to fire and to logging damage (7); both can
lead to various wood rots.
Nectria magnoliae causes cankers on small or suppressed
Fraser magnolia trees (10). Whenever such trees become dominant
or crown free, the cankers often heal. Fungi capable of causing
rot of the central cylinder or in wounds are Ganoderma
applanatum, Fomes geotropus, Daedalea ambigua, Polyporus
calkinsii, P curtisii, and Laetiporus sulphureus. White
heartrot in living trees is caused by Fomes sclerodermeus.
Sprout leaves may be heavily attacked by common powdery
mildew, Phyllactinia guttata. Phyllosticta magnoliae causes
a large black leaf spot. Phoma pedunculi and Cytospora
tumulosa occur on branches. Fraser magnolia probably cannot
withstand prolonged inundation, as evidenced by the cool, moist,
but well-drained sites where it generally grows.
Several insect species can damage, if not kill, Fraser magnolia.
Euzophera ostricolorella attacks the base of mature trees
and E. magnolialis kills seedlings (1). The
ambrosia beetle, Platypus compositus, makes tunnels and
larval cradles in the wood. Xyloterinus politus breeds in
injured, dying, and recently cut trees, severely degrading lumber
of infested wood because of adult tunneling. Larvae of the June
beetle, Phyllophaga forsteri, feed on roots, and adults
feed on foliage. Magnolia scale, Neolecanium cornuparuum feeds
on current-year twig growth, seriously weakening and sometimes
killing host trees.
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Flowering and Fruiting
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Fraser magnolia has perfect
flowers. The blossoms open from May to June depending on
latitude, elevation, and weather conditions. The solitary flowers
are about 20 to 30 cm (8 to 12 in) wide; they consist of six to
nine obovatespatulate petals conspicuously constricted below the
middle (9,16). The fruit is an oblong, conelike aggregate
of fleshy one- or two-seeded follicles, that ripen in late summer
to early fall. At maturity, the red, drupelike seeds are about
1.5 cm (0.6 in) long.
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Genetics
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Certain distribution patterns are affected by polyploidy. Among
magnolias, the relatively sharply peaked and restricted diploids,
Fraser magnolia and umbrella magnolia, may be compared with the
tetraploid cucumbertree (21). Supposedly, a diploid species with
extensive ecotypic variation should have a wider range than a
polyploid derived from it; how ever, cucumbertree has the widest
range of all three species.
No races or hybrids of Fraser magnolia have been reported, but a
variety, Magnolia fraseri var. pyramidata (Bartr.)
Pampanini, is occasionally mentioned (13).
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Growth and Yield
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On most mesic sites, where Fraser
magnolia does best, its sprouts grow vigorously from sapling to
pole stage. In a Blue Ridge gorge, it was the last tree to begin
growth in spring 1965 and 1966, but it grew very rapidly until
growth cessation in late August (14). Peak growth occurred at or
below midslope. Average circumferential 3-year growth measured by
band dendrometer at d.b.h. was 1.08 cm (0.424 in). On the flat,
moist bottom land between slopes, Fraser magnolia trees were
even-aged, about 50 years old, and formed part of a closed
canopy.
In an intensive cleaning study established in spring 1960 in an
11-year-old mixed hardwood sapling stand near the Pink Beds on
Pisgah National Forest, NC (5), 14-year diameter growth of the
four largest trees on one 0.01-ha (0.025-acre) plot was measured.
Site quality was 28.7 m (94 ft) for yellowpoplar; there were
2,076 trees per hectare (840/acre) and 3.44 m²/ha (15 ft²/acre)
of basal area after cleaning. Results were as follows:
Species
Diameter
at age (yr)
11
14
17
21
25
cm
cm
cm
cm
cm
Fraser Magnolia
9.1
13.7
17.0
19.6
22.1
Yellow-poplar
5.8
10.9
14.7
20.6
26.7
Northern red oak
6.9
10.4
12.4
16.3
17.8
Sweet birch
4.1
7.1
10.2
14.0
15.5
in
in
in
in
in
Fraser magnolia
3.6
5.4
6.7
7.7
8.7
Yellow-poplar
2.3
4.3
5.8
8.1
10.5
Norhtern red oak
2.7
4.1
4.9
6.4
7.0
Sweet birch
1.6
2.8
4.0
5.5
6.1
The 14-year increase in diameter for Fraser magnolia was 13.0 cm
(5.1 in); for yellow-poplar, 20.8 cm (8.2 in); for northern red
oak, 10.9 cm (4.3 in); and for sweet birch, 11.4 cm (4.5 in)
(19). Although at age 11 Fraser magnolia was larger than
yellow-poplar by 3.3 cm (1.3 in), by age 21 yellow-poplar had
exceeded it in size and was 4.6 cm (1.8 in) larger at age 25. At
that time the plot contained 22.96 m² /ha (100 ft²
/acre) of basal area and the stand was reduced to 1,483 trees/ha
(600 trees/acre). This example serves to illustrate that Fraser
magnolia sprout growth can be rapid in the early years of an
even-aged stand. By maturity, however, Fraser magnolia is an
intermediate tree in relation to the stand canopy. In this
regard, growth of Fraser magnolia resembles that of Carolina
basswood and cucumbertree; all three generally grow slower than
yellow-poplar.
Fraser magnolia needs sunlight for growth and survival. This is
shown by its generally contorted bole and branches, which result
from growing leaders constantly twisting to exploit light from
small openings. Occasionally a forest-grown Fraser magnolia can
become as large as 61 cm (24 in) d.b.h. and 24 m (80 ft) tall
(7). The largest tree on record, growing in Philadelphia, PA, has
a d.b.h. of 81 cm (32 in), a total height of 20 m (65 ft), and a
crown spread of 15 m (50 ft).
No Fraser magnolia grows in the mountain counties of Virginia
northeast of Roanoke Gap. The greatest volume is found in western
Virginia, followed by North Carolina. Lesser volumes are found in
West Virginia, Kentucky, and Tennessee, but specific data are not
available (11).
Stand and stocking data for Fraser magnolia in the Southeastern
States are shown in table 1. Pulpwood-size trees through the 25.4
cm (10 in) diameter class account for 81 percent of the
cubic-foot volume and 91 percent of the trees. The largest trees
fall only into the 40.6 cm (16 in) diameter class and constitute
less than 1 percent of all trees but 19 percent of total
board-foot volume. Yields per acre are unavailable because of the
sporadic occurrence and low density of Fraser magnolia.
D.b.h. class
Number of trees
Merchantable
stem volume in thousands
Saw log
volume in thousands
thousands
m³
ft³
m³
fbm¹
15 cm or 6 in
2,004
129.2
4,566
--
--
20 cm or 8 in
1,771
319.2
11,279
--
--
25 cm or 10 in
763
235.7
8,328
--
--
30 cm or 12 in
206
88.9
3,143
33
5,782
36 cm or 14 in
102
53.5
1,889
37.9
6,649
41 cm or 16 in
21
16.4
579
17
2,983
Total
4,867
842.9
29,784
87.9
15,414
¹International
0.25-inch log rule.
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Reaction to Competition
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Fraser magnolia responds best to
some form of even-age management. It is classed as being
intermediate in tolerance to shade. Clearcutting is one way to
regenerate it. At best, however, Fraser magnolia is likely to
constitute less than 10 percent of any stand (3,8). Since most of
the regeneration is of sprout origin (7,14), it is highly
dependent on the availability and distribution of Fraser magnolia
trees in the original stand. Any additional trees that develop
are likely to be seedling sprouts from damaged prelogging
seedlings. Since many seedlings are found in mature stands, a one
or two-cut shelterwood would help seedlings grow t( sapling size
before the final harvest cut, and in this way they would have a
competitive advantage over faster growing, more intolerant
species. Because Fraser magnolia grows in clumps, early release
by precommercial thinning to one stem accelerates its diameter
growth and improves its form. Although Fraser magnolia can
compete well on most sites with associated tree species for the
first 40 or 50 years, at best it is short-lived and is prone to
drop out of stands when it is 60 to 70 years old. When
intermediate thinnings are part of stand management, as opposed
to custodial management, Fraser magnolia is very often one of the
first trees to be cut because of its generally poor form and
susceptibility to damage. There is little incentive to manage it
in the hope of producing high-quality timber.
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Rooting Habit
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Fraser magnolia seedlings have a deeply
penetrating taproot. By the time seedlings become saplings,
lateral roots are well developed (7). Because of generally loose,
friable soils, the root configuration of the trees remains
unchanged through maturity except that roots grow larger.
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Seed Production and Dissemination
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A good seed crop occurs
only every 4 to 5 years. Cleaned seeds range from 5,470 to
12,460/kg (2,480 to 5,650/lb), averaging 10,030/kg (4,550/lb)
(14,18).
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Seedling Development
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Germination is epigeal. Stratified
seeds placed in a sandy medium and kept at day and night
temperatures of 30° C (86° F) and 20° C (68°
F), respectively, from 40 to 100 days, have a germinative
capacity of 8 to 21 percent-low in comparison to other magnolias
(18). In spite of low germinative capacity, Fraser
magnolia is one of the tree species that colonizes canopy gaps
caused by the fall of single, large eastern hemlocks in the Great
Smoky Mountains (2). It is also common as volunteer
regeneration along logging roads in the southern Appalachians and
is found frequently as seedlings and saplings in small openings
on mesic sites near seedbearing trees.
Foliage begins expanding the last week in April. Radial growth
initiates in middle to late May and continues until the second
week of August; at times it may last until the first week of
September (14). Seedling reproduction is regarded as slow
growing over most of its range when it is under closed or even
partial canopies; however, Fraser magnolia seedlings even in
clearcuts quickly fall behind other fast-growing intolerant
species such as yellow-poplar, black cherry, and sweet birch.
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Soils and Topography
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Fraser magnolia is generally found on mesic sites, but seedlings
and saplings have been reported to occur on subxeric and even on
xeric sites (4,8,14,15,21). In the gorges of the southern Blue
Ridge Front, it is more frequently found below midslope, being
most common on the lowest third of north and south slopes, and on
the bottom land. In the gorge region it has an unusual habit of
growing in a multiple- stemmed group on bottoms and as a
single-stemmed tree on slopes; elsewhere it occurs in either
form. Sites on which it grows best are generally protected,
moist, and fertile; soil temperatures on such sites are generally
cool during the growing season in comparison with sites farther
upslope.
On lower slopes and in the bottom of the Long Spur River Gorge in
the southeastern escarpment of the Blue Ridge Mountains between
Rosman and Highlands, NC, average chemical contents and other
properties of the 0 to 13 cm (0 to 5 in) soil layer of the
Tusquitee loam (an Umbric Dystrochrept of the order Inceptisols)
supporting Fraser magnolia were as follows: sodium, 0.9 meq/100
g; potassium, 0.20 meq/100 g; calcium, 0. 10 meq/100 g; and
magnesium, 0.11 meq/100 g; nitrous nitrogen, 1.6 p/m; phosphorus,
2.0 p/m; and iron, 1.9 p/m; pH 4.8; and organic matter, 6.6
percent (14,20). The nutrient status of this soil is low because
plentiful soil moisture makes nutrients quickly available to all
plants, and the nutrients are thus tied up until the plants are
recycled.
In the Great Craggy Mountains above Dillingham, NC, at an
elevation of 1200 m (3,940 ft) where the northwest slope averages
40 percent, the following average soil values prevail in a stand
composed mostly of sugar maple (Acer saccharum), American
beech (Fagus grandifolia), yellow buckeye (Aesculus
octandra), and Carolina basswood (Tilia caroliniana),
and some Fraser magnolia: pH 4.8, organic matter 7 percent,
bulk density 0.96 g/cm³ (59.9 lb/ft³ ). The top 15 cm
(6 in) of mineral soil contained phosphatephosphorus 1.7 kg/ha
(1.5 lb/acre), potassium 118 kg/ha (105 lb/acre), calcium 936
kg/ha (835 lb/acre) and magnesium 108 kg/ha (96 lb/acre) (6). The
soils are mostly Edneyville stony loam which is a mesic Typic
Hapludult of the order Ultisols (20): parent materials are
Precambrian acid crystalline rocks, including gneisses, schists,
granite, diorite, and some mica-gneisses and mica-schists.
Farther northeast, near Grandfather Mountain (1956 m or 6,417 ft)
in the Blue Ridge Front, Fraser magnolia grows on Ashe soil, a
Typic Dystrochrept derived from Cranberry granite at an elevation
of about 1200 m (3,940 ft). The terrain slopes steeply to the
southeast, and the soils are deep, coarse, conspicuously
gray-white sandy loams or loams which are very well drained.
Rainfall is well distributed and plentiful throughout the year so
soil moisture is ample and not restrictive to forest growth.
On the Jefferson National Forest in western Virginia, Fraser
magnolia is found mostly on soils developed from sandstone or
shale. In the Appalachian Plateau of West Virginia, it grows on
rich, moist, colluvial soils derived from upper-Devonian and
Pennsylvanian rock formations (3,7). Fraser magnolia generally
grows at elevations ranging from 500 to 1700 m (1,640 to 5,580
ft) but is most common from about 600 to 1300 m (1,970 to 4,270
ft).
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Special Uses
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In the lumber trade, Fraser magnolia is included with
yellow-poplar sawtimber and pulpwood (7). It has little value as
firewood and generally has little value as sawtimber because of
sweep and crook. Wildlife use larger defective trees of Fraser
magnolia as den trees. Sprouts are browsed. In a mountainous area
of western North Carolina, where Fraser magnolia sprouts occurred
with a frequency of 20 percent and a density of 717 stems per
hectare (290/acre), the species was 37-percent utilized by
white-tailed deer (5).
Frequent use is made of Fraser magnolia as an ornamental (16).
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Vegetative Reproduction
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Although Fraser magnolia
seedlings have difficulty in surviving to even an intermediate
canopy position, stump sprouts survive more easily. It is highly
possible that many, if not most, of the larger Fraser magnolia
trees in the Appalachian forest region are of stump sprout
origin; possibly many are seedling sprouts (7). In this growth
habit, the species closely resembles yellowpoplar and northern
red oak. Seemingly, clearcutting with resultant sprout growth is
the best way of reproducing Fraser magnolia.
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Distribution
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Restricted mostly to the Appalachians, Fraser magnolia is found in
moist habitats in the mountains of West Virginia, generally in
the eastern half of the State, in western Virginia, in the
southern Appalachians of east Tennessee and western North
Carolina, and in the Blue Ridge Mountains of northwestern South
Carolina and northeast Georgia (12,13). It also grows in the
Cumberland Mountains of southeastern Kentucky.
-The native range of Fraser magnolia.
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Brief Summary
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Magnoliaceae -- Magnolia family
Lino Delia-Bianca
Fraser magnolia (Magnolia fraseri), also called mountain
magnolia, earleaf cucumbertree, umbrellatree, or mountain-oread,
is a fast-growing small tree scattered in the hardwood forests of
the lower Appalachian slopes. It grows best on rich, moist,
well-drained soils. The very large showy white flowers and large
coarse foliage make this an attractive ornamental; otherwise it
has little commercial value. The lumber is mixed with associated
hardwoods for sawtimber and pulpwood, and the fruit is eaten by
wildlife (9,16).
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