Comments
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Betula lenta is a dominant tree in the northern hardwood forests of the northern Appalachians and a valuable source of timber. It was formerly the chief commercial source of wintergreen oil (methyl salicylate), which is distilled from its wood. Betula lenta is most easily separated from B . alleghaniensis by its close bark and the glabrous scales of infructescences.
Native Americans used Betula lenta medicinally to treat dysentery, colds, diarrhea, fevers, soreness, and milky urine, and as a spring tonic.
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Description
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Trees , to 20 m; trunks tall, straight, crowns narrow. Bark of mature trunks and branches light grayish brown to dark brown or nearly black, smooth, close, furrowed and broken into shallow scales with age. Twigs with taste and odor of wintergreen when crushed, glabrous to sparsely pubescent, usually covered with small resinous glands. Leaf blade ovate to oblong-ovate with 12--18 pairs of lateral veins, 5--10 × 3--6 cm, base rounded to cordate, margins finely and sharply serrate or obscurely doubly serrate, teeth fine, sharp, apex acuminate; surfaces abaxially mostly glabrous, except sparsely pubescent along major veins and in vein axils, often with scattered, minute, resinous glands. Infructescences erect, ovoid to nearly globose, 1.5--4 × 1.5--2.5 cm, usually remaining intact for a period after release of fruits in fall; scales mostly glabrous, lobes diverging at or proximal to middle, central lobe short, cuneate, lateral lobes extended to slightly ascending, longer and broader than central lobe. Samaras with wings narrower than body, broadest near center, not extended beyond body apically. 2 n = 28.
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Distribution
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Ont.; Ala., Conn., Ga., Ky., Maine, Md., Mass., Miss., N.H., N.J., N.Y., N.C., Ohio, Pa., R.I., S.C., Tenn., Vt., Va., W.Va.
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Flowering/Fruiting
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Flowering late spring.
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Habitat
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Rich, moist, cool forests, especially on protected slopes, to rockier, more exposed sites; 0--1500m.
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Associated Forest Cover
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Sweet birch is a minor species in 12 Society of American Foresters
cover types (3):
19 Gray Birch-Red Maple
20 White Pine-Northern Red Oak-Red Maple
21 Eastern White Pine
22 White Pine-Hemlock
24 Hemlock-Yellow Birch
25 Sugar Maple-Beech-Yellow Birch
27 Sugar Maple
28 Black Cherry-Maple
39 Black Ash-American Elm-Red Maple
57 Yellow-Poplar
58 Yellow-Poplar-Eastern Hemlock
59 Yellow-Poplar-White Oak-Northern Red Oak
In the southern Appalachian region, sweet birch reaches its best
development in Types 21, 22, 25, 57, 58, and 59.
Important associated tree species include
yellow-poplar (Liriodendron tulipifera), basswood (Tilia
spp.), white ash (Fraxinus americana), sugar maple
(Acer saccharum), red maple (A. rubrum), northern
red oak (Quercus rubra), white birch (Betula
papyrifera), gray birch (B. populifolia), hemlock
(Tsuga spp.), and eastern white pine (Pinus strobus).
Understory vegetation varies with locality, but commonly
associated shrubs are mountain maple (Acer spicatum), striped
maple (A. pensylvanicum), flowering dogwood (Cornus
florida), downy serviceberry (Amelanchier arborea), American
hornbeam (Carpinus caroliniana), and eastern hophornbeam
(Ostrya virginiana). Associated herbaceous vegetation
includes Solomons-seal (Polygonatum pubescens), marsh
blue violet (Viola cucullata), clubmosses (Lycopodium
spp.), mayapple (Podophyllum peltatum), trilliums
(Trillium spp.), jack-in-the-pulpit (Arisaema
atrorubens), and a variety of ferns. In former clearcut areas
where young stands are established, blackberry (Rubus spp.)
is abundant.
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Climate
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Precipitation in the range of sweet birch averages about 1140 mm
(45 in) a year, about half of it falling during the growing
season. In the northern part of the range, snowfall averages 200
to 250 cm (80 to 100 in) a year. Average annual temperature is
about 7° C (45° F) in the north and about 13° C
(56° F) in the southern Appalachians. The July average is 21°
C (70° F) in New England and 23° C (74° F) in the
southern Appalachians. Mean January temperatures are -9° to
-7° C (15° to 20° F) in New England and -1°
to 4° C (30° to 40° F) in the southern
Appalachians. The growing season varies from 90 to 220 days,
depending on latitude and elevation.
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Damaging Agents
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In northwestern Pennsylvania, glaze
storms have caused appreciable damage to crowns of sweet birch
trees. Available data indicate, however, that this species may be
rated as intermediate to fairly resistant to glaze in comparison
with other northern hardwoods and common associates (7). In
addition to the primary effects of ice damage in directly
reducing crown volume, glaze storms may contribute to the decline
and subsequent death of both yellow and sweet birches by allowing
wood decay organisms to enter or, possibly, by causing crown
deterioration from sudden excessive exposure.
Sweet birch does not seem to be very susceptible
to winter killing. The severe winter of 1942-43 partly or
completely killed trees of many species in Maine, but sweet birch
appeared to be uninjured (7).
A study of the effects of the 1930 drought on oak
forests in central Pennsylvania indicated that sweet birch is
intermediate in drought resistance. Drought caused mortality
reduced basal area by 36 percent, for sweet birch, 11 percent for
sugar maple, 50 percent for red maple, and 15 percent for white
ash (7).
Several fungi attack living sweet birch trees, and
sterns frequently become highly defective at an early age. In
unmanaged sawtimber stands in the anthracite, region of
Pennsylvania, cull exceeded 20 percent of' the total cubic-foot
volume of trees 43 cm (17 in) in diameter on Site 1 and 23 cm (9
in) on Site II (7). The most important pathogens are, white trunk
rot (Phellinus igniarius), yellow cap fungus
(Pholiota limonella), and Nectria canker (Nectria
galligena) (5). Sweet birch is one of the most susceptible
species to Nectria canker. Cankers on the bole are more serious
than branch cankers because they reduce merchantable volume and
increase susceptibility to stem breakage.
Sweet birch is easily damaged by ground fires
because it has extremely thin bark. Several fires may kill the
tree, but even light scorching at the base of the tree will lower
its resistance to the attacks of various diseases or insects such
as the ambrosia beetle (Xyloterinus politus) (9).
Several leaf-feeding insects occasionally infest
sweet birch. The most prevalent ones are birch tubemaker (Acrobasis
betulella), birch skeletonizer (Bucculatrix
canadensisella), orientalmoth (Cnidocampa
flavescens), gypsy moth (Lymantria dispar), and dusky
birch sawfly (Croesus latitarsus) (6).
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Flowering and Fruiting
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Sweet birch flowers are
monoecious and borne in catkins. Staminate catkins are formed in
late summer or autumn and open in the spring after elongating to
about 20 mm (0.75 in). Pistillate catkins appear with the leaves
and are borne terminally on short, spurlike branches. Flowers
open in April and May. Seeds ripen from about mid-August through
mid-September and are contained in erect strobili (1).
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Genetics
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Sweet birch is closely related to yellow birch. Efforts to cross
the two species have been successful, but the F, hybrids have low
vigor and seed germination rates (11). No natural hybrids have
been verified.
Virginia round-leaf birch, Betula uber, at
one time was classified as Betula lenta var. uber.
The known population of this species consists of 12 mature
trees, 1 sapling, and 21 seedlings in Smythe County, VA (10). In
1978, it was officially listed as an endangered species.
A natural hybrid of Betula lenta and B.
pumila that occurred at the Arnold Arboretum was designated
B. jackii.
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Growth and Yield
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Sweet birch saplings grow relatively
rapidly. The following data have been reported: In northwestern
Pennsylvania, at age 12, 1.8 m (6 ft) in height; in western
Pennsylvania and central West Virginia, at age 20, 14 m (46 ft)
in height and 10 cm (4 in) in d.b.h.
On the very best sites, sweet birch grows 21 to 24
m (70 to 80 ft) tall and 61 to 152 cm (24 to 60 in) in d.b.h. In
most areas, however, it is a tree of medium size, 15 to 18 m (50
to 60 ft) tall and 61 cm (24 in) or less in diameter. One of the
largest trees on record is 147 cm (58 in) in d.b.h. and 21 m (70
ft) tall.
According to a study in virgin hemlock-hardwood
stands in northwestern Pennsylvania, sweet birch saplings in the
understory grow about twice as fast as hemlock, beech, sugar
maple, and red maple slightly faster than yellow birch, and at
about the same rate as black cherry (Prunus serotina) (7).
Data from plots on apparently average sites in
Delaware County, NY, and Forest and Potter Counties, PA, show
that sweet birch can attain a diameter at breast height of about
10 cm (4 in) in 20 years, 18 cm (7 in) in 40 years, and 25 cm (10
in) in 80 years (7). In unmanaged sites in the anthracite region
of Pennsylvania, sweet birch reached 36 cm (14 in) d.b.h. in 85
years on high sites (Site 1) and 30 cm (12 in) in 80 years on
average sites (Site 11). It is estimated that in managed stands,
the same sizes would be reached in 10 to 15 years less time (7).
In the Pennsylvania anthracite region, periodic
cubic volume production begins to decline when the trees are 36
to 41 cm (14 to 16 in) in d.b.h. (7); that is, in about 100
years. Older trees are common and two individuals 192 and 265
years old have been found in Pennsylvania (7).
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Reaction to Competition
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Sweet birch is classed as
intolerant of shade. A long, fairly dean bole is developed in
dense stands, while low, thick branches are produced on
open-grown trees. Sweet birch may seed in heavily after
clearcutting in the Appalachian region, but a majority of the
stems succumb to competition by age 20 (4). Sweet birch is one of
the species that has replaced American chestnut in stands where
chestnut was once a major component. Sweet birch has been
reported to occupy 15 to 20 percent of the basal area of
40-year-old stands in Connecticut (12), all-aged stands in
southwestern North Carolina (8), and 20-year-old even-aged stands
in West Virginia. In a 70-year-old even-aged stand in West
Virginia, 20 years of uneven-age management did not significantly
change the proportion of sweet birch, which remained at about
18 percent of the basal area of stems 13 cm (5 in) and larger in
diameter (13).
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Rooting Habit
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No informationavailable.
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Seed Production and Dissemination
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Seed fall is during
mid-September through November. Seed dispersal is normally by
wind and seeds may be blown some distance over crusted snow.
Nothing is known about quantities of seeds produced or how far
they are spread. Seed production begins when trees are about 40
years old; large seed crops are produced every 1 or 2 years.
Cleaned sweet birch seeds average 1,367,000/kg (620,000/lb) (1).
Recommended storage conditions for birch seeds are 1 to 3 percent
moisture content at 2° to 3° C (36° to 38° F)
(1). Stratification does not generally improve germination, but
best germination is obtained when seeds are tested under light
(1).
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Seedling Development
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Under forest conditions, seeds
normally germinate during the spring after they are dispersed.
Nursery experience indicates that germination may extend over 4
to 6 weeks. Germination is delayed when the embryo is dormant.
Moist mineral soils, rotten logs, and humus are suitable
germination media.
In nursery practice, birch seed is usually sown in
the fall after collection in the late summer or fall. Seeds are
broadcast and covered as lightly as possible or not at all if the
seedbed is to be kept moist. Epigeal germination is usually
complete 4 to 6 weeks after sowing.
Seedlings require light shade for 2 to 3 months
during the first summer. Tree percent is low; only 10 to 20
percent will produce 1-0 seedlings. Desirable seedling density is
270 to 485/m² (25 to 45/ft²). Usually 1-0 and 2-0
barerooted seedlings are planted (1).
Sweet birch seedlings develop best during their
early years when protected by side shade or light overhead shade.
Scattered individuals frequently grow as advance reproduction in
openings in mature stands or under younger stands of light to
moderate crown density. In the Harvard Forest, sweet birch is
sometimes present in the advance hardwood growth under old-field
white pine about 50 to 70 years old (7). On fairly cool, moist
sites-sheltered ravines, north to east aspects, or moderately
heavy soils-heavy cutting or clearcutting of these stands
generally results in a higher proportion of sweet birch in the
succeeding reproduction than was present in the advance growth.
On the other hand, studies in northwestern Pennsylvania have
shown that clearcutting of immature second-growth northern
hardwood stands before an understory has developed is followed by
an abundance of intolerant species with only a poor
representation of sweet birch and tolerant hardwoods (7).
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Soils and Topography
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Sweet birch grows primarily on three soil orders: Spodosols,
Inceptisols, and Ultisols. It grows best on moist, well-drained
soils but is also found on a variety of less favorable sites with
rocky coarse-textured or shallow soils (7). Because it is
occasionally abundant on rocky mountains in Pennsylvania, sweet
birch may be valuable for soil protection. On other poor soils,
however, such as the excessively dry portions of the Harvard
Forest in Massachusetts, sweet birch is partially or completely
replaced by oaks and conifers.
Sweet birch grows over a wide range of altitudes
from near sea level along the New England coast to an upper
extreme of 1220 to 1370 m (4,000 to 4,500 ft) in the southern
Appalachian Mountains. In New England, the species is fairly
common in southern Maine, the highlands of New Hampshire, western
Vermont, the highlands of Massachusetts and Rhode Island, and
throughout Connecticut. In the southern Appalachians, where sweet
birch grows best, the optimum elevation is between 610 and 1370 m
(2,000 and 4,500 ft).
Moist, protected northerly or easterly slopes are
considered most favorable for sweet birch in both northern and
southern parts of its range.
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Special Uses
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Sweet birch wood is quite similar to yellow birch (2). Lumber and
veneer of the two species often are not separated in the market,
although production of yellow birch far exceeds that of sweet
birch. Sweet birch is used for furniture, cabinets, boxes,
woodenware, handles, and millwork, such as interior finish and
flush doors. Paper pulp made from sweet birch is used in various
amounts with other pulps to produce such products as boxboards,
book and newsprint paper, paper toweling, and corrugated paper.
Birch oil has been produced commercially from sweet birch bark,
but its use has declined with the introduction of synthetic
products.
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Vegetative Reproduction
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Sweet birch has been known to
reproduce well from small stumps but seems to be less prolific
than many of its associates maple, sugar maple, beech (Fagus
grandifolia), yellow-poplar, and northern red oak.
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Brief Summary
provided by Silvics of North America
Betulaceae -- Birch family
Neil I. Lamson
Sweet birch (Betula lenta), also commonly referred to as
black birch or cherry birch, was at one time the only source of
oil of wintergreen. It is the aroma of wintergreen emanating from
crushed leaves and broken twigs to which this birch owes its
common name, sweet. Its specific name, lenta, is
derived from the tough yet flexible twigs that characterize the
species. The wood is also unique. When exposed to air it darkens
to a color resembling mahogany and, in times past, was used as an
inexpensive substitute for the more valued tropical wood.
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Distribution
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Sweet birch is primarily a tree of the northeastern United States.
It grows from southern Maine westward in southern Quebec, New
Hampshire, Vermont, New York, and southeastern Ontario to eastern
Ohio; and south in Pennsylvania through the Appalachian Mountains
to northern Alabama and Georgia. Forest survey data indicate that
sweet birch is most abundant in Massachusetts, Connecticut, New
York, and Pennsylvania.
-The native range of sweet birch.
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Betula lenta
provided by wikipedia EN
Betula lenta (sweet birch, also known as black birch, cherry birch, mahogany birch, or spice birch) is a species of birch native to eastern North America, from southern Maine west to southernmost Ontario, and south in the Appalachian Mountains to northern Georgia.
Characteristics and habitat
Betula lenta is a medium-sized deciduous tree reaching 30 m (98 ft) tall, exceptionally to 35 metres (115 ft)[2] with a trunk up to 60 cm (2.0 ft) diameter. Heights of 50 feet (15 m) to 80 feet (24 m) are more typical. In younger trees the bark is characteristic of most birches, with smooth bark and distinct horizontal lenticels. It is sometimes mistakenly identified as a cherry tree. In older tree specimens the bark (unlike the more commonly known birches) develops vertical cracks into irregular scaly plates revealing rough dark brown bark patterns. This, however, only occurs in mature, or ancient, trees and these specimens are not often identified by the public as B. lenta due to the difference between the tree's smooth young bark (which the public is most familiar with) and the tree's rough, cracked and plated mature bark. The twigs, when scraped, have a strong scent of wintergreen due to methyl salicylate, which is produced in the bark. The leaves are alternate, ovate, 6–15 cm (2.4–5.9 in) long and 4 to 8 cm (1.6–3.1 in) broad, with a finely serrated margin.[3] The flowers are wind-pollinated catkins 2.5–3 cm (0.98–1.2 in) long,[3] the male catkins pendulous, the female catkins erect. The fruit, maturing in fall, is composed of numerous tiny winged seeds packed between the catkin bracts. Seed production mainly occurs in trees that are between 40 and 200 years old, although light crops may occur as early as 15 years and as long as the tree lives.
Age
The oldest known B. lenta has been confirmed to be 368 years old,[4] and the species may live even longer in an undisturbed ancient forest. Due to the cracking and developing of bark plates, a rough age estimate can be determined by how many bark layers a tree has. Generally the tree's smooth young bark begins to split around 40–50 years of age, and then begins to peel off the trunk around the age of 70-80. It is then replaced by another layer of bark, which will begin to peel at around 130–150 years. The third layer will peel when the tree has reached 200–210 years and achieved "old growth" status. This will continue to occur as long as the tree lives, but the individual bark layers become indiscernible after roughly 250 years of age.
Black birch seeds at a prolific rate and quickly colonizes disturbed areas. In the Northeastern US in the 1980s, infestations of gypsy moths, Hemlock woolly adelgid, and Discula destructiva killed many trees, and their place was taken by black birch.
Uses
The wood of black birch is heavy at 47 pounds per cubic foot and is used for furniture, millwork, and cabinets. It is similar to yellow birch wood and often not distinguished from it in the lumber trade.
The sap flows about a month later than maple sap, and much faster. The trees can be tapped in a similar fashion, but must be gathered about three times more often. Birch sap can be boiled the same as maple sap, but its syrup is stronger (like molasses). It can be used to make birch beer.[5] Boiling also destroys volatile quantities of wintergreen oil.[3]
The inner bark can be eaten raw as an emergency food. The twigs and inner bark can be steeped to make tea.[3]
Black birch was once harvested extensively to produce oil of wintergreen, the tree was borderline endangered until the 1950s-60s when synthetic oil of wintergreen appeared.
Ecology
The leaves of this species serve as food for some caterpillars and the solitary leaf-cutter bee Megachile rubi cuts pieces from the leaves to line the cells of its nest.[6]
Deer do not tend to browse young B. lenta allowing trees to grow in areas with high deer populations, Betula alleghaniensis, a close relative of B. lenta, is, however, heavily browsed by deer. This accounts for a lack of B. alleghaniensis and an abundance of B. lenta where deer populations are high. In abandoned fields, B. lenta is often thicket forming and protects trees not resistant to deer browsing.
Closeup of bark beginning to crack and peel its first layer
References
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Betula lenta: Brief Summary
provided by wikipedia EN
Betula lenta (sweet birch, also known as black birch, cherry birch, mahogany birch, or spice birch) is a species of birch native to eastern North America, from southern Maine west to southernmost Ontario, and south in the Appalachian Mountains to northern Georgia.
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