Sugar Maple
 Physical information
Sugar Maple
belongs to the hard maples of the family Aceraceae. It is also called rock maple. Like all
members of the Maple family, it constitutes one of the most ornamentals for planting in
lawns, along the streets, and in parks. Sugar maple is deciduous, dropping its leaves at
the end of the growing season. It shows excellent bright-orange fall foliage and an
attractive form. Its leaves are 7.5 to 13 cm (3 to 5 in) across and usually have five
lobes that are separated by rounded, shallow indentations; the lower two lobes are rather
small. The margins of the leaves are indented with sparse, large, pointed teeth. Under
ideal conditions, sugar maples grow to 23-30 m (75-100ft) tall, with trunk diameters of
0.9 to 1.2 m (3 to 4ft). The flowers are generally small and inconspicuous and are borne
in clusters.
Soil and topography
Loamy sands, sandy loams, loams, and
occasionally silt loam soils support the better stands of sugar maple with the best
development occurring on the loam soils. The species thrives only on fertile, moist, and
well-drained soils of all soil types. Yield and quality of sugar maple stands increase as
soil fertility and moisture conditions improve. However, it does grow on poor, dry,
shallow soils, but it is never thrifty there and is rarely, if ever, found in swamps.
Sugar maple can be found on soils ranging
from strongly acid (pH 3.7) to slightly alkaline (pH 7.3), but most commonly grows on
soils having a reaction of pH 5.5 to 7.3. The leaf litter of sugar maple contains about
1.81 percent calcium, 0.24 percent magnesium, 0.75 percent potassium, 0.11 percent
phosphorus, 0.67 percent nitrogen, and 11.85 percent ash, based on dry weight. The pH of
the leaves ranges from 4.0 to 4.9. The calcium content of the leaves is relatively uniform
in trees growing on surface soil with a pH range of 4.5 to 7.0, but drops rapidly as the
soils become more acid.
The narrow range of height differences on
various soil types suggests that sugar maple has more exacting site requirements than many
of its conifer associates. In northern New England and New York State, sugar maple
occurs at elevations up to 2,500 feet. In the Lake States, such as Michigan and Wisconsin,
it is found up to 1,600 feet. In the southern Appalachians it occurs in a zone from 3,000
to 5,500 feet.
Distribution
Sugar Maple is one of the largest and most important of the
hardwoods in the eastern half of the United States and Canada. The range of sugar maple
extends from Nova Scotia, and Quebec, west to Ontario, southeastern Manitoba, and western
Minnesota, south to central Iowa, eastern Kansas and Missouri, east to Tennessee and
northern Georgia. Most of the important stands are found in the Lake States, Ohio,
Pennsylvania, New York, and in the southern Appalachians and Canada. This species is not
found in the South Atlantic or Gulf Coastal Plains.
Within the range of sugar maple the average January
temperatures range from 0º to 50º F; the average July temperatures, 60º to 80º F.
Maximum temperatures range from 90º to 100º F. The average annual precipitation is 20 to
50 inches over most of the range but reaches 80 inches in some southern Appalachian
localities. The average warm season (April to September) precipitation varies from 15 to
40 inches. There are from 1 to 150 inches of snow each year.
Economic uses
Sugar Maple's trunk is made of hard wood. Maple wood is
used principally for lumber, distilled products, veneer, crossties, and pulpwood. Most of
the lumber is used for flooring, furniture, crates, and interior finishing. A certain
amount of maple wood is crushed, chipped, and distilled to produce acetic acid and
alcohol.
Medicinal
uses
None reported.
Special
features of sugar maple
Maple
syrup
Maple syrup is made from the "sweetwater" sap of
sugar maple, but also of the black maple (Acer nigrum) and the red maple (Acer
rubrum). Because of a physiological process that is not yet clearly understood, these
maples will bleed quantities of sap through wounds in the trunk under conditions of
alternate freeze and thaw in late winter and early spring. The sap may contain up to 10%
sugar. It is reduced by boiling to a sweet syrup, or, with further boiling, to a solid
sugar. Both the syrup and the sugar have a distinctive flavor and color not present in the
sap but developed through boiling.
The syrup has been made in Canada and the United States
since the first colonial settlers learned the art from the Indians. Both syrup and sugar
were important items of trade until the late 1800s, when white cane sugar became less
expensive to use as a sweetener. Nowadays the Canadian province of Quebec produces by far
the largest amount of syrup-some 75 million liters (20 million gallons) yearly. Vermont
and New York are the principal U.S. producers, followed by Michigan, Wisconsin, Ohio, and
Pennsylvania.
Maple sap is harvested during a 4 to 6 week period between
January and April, although in some years warm night-time temperatures may cut short
harvest. The sap dripped from the trees is boiled in an evaporator. When the concentrated
sap reaches a level of 66.5% sugar, it is drawn off, filtered, and bottled. It usually
requires at least 32 gallons of sap to make a gallon of syrup or 8 pounds of sugar.
Principal
enemies and reaction to competition
Sugar maple is very tolerant of shade and is able to
withstand several years in complete suppression and still shows a strong response to
release.
Sugar maple is relatively wind firm and can usually
withstand winds up to tornado force without being wind-thrown especially if growing on the
deeper soils. In northern Michigan, uprooting was the least important of recognized causes
of loss in mature stands except in the heavy cutting.
Red squirrels and gray squirrels occasionally gnaw off the
tips of branches or eat the bark and flowers. They usually feed on sugar maple during the
late winter of early spring when the sap is flowing. Porcupines also may feed on the bark
to the extent the tree dies.There are other enemies to sugar maple such as, some common
fungi (Armillaria mellea and Ustulina vulgaris). Fortunately,
sugar maple is not highly susceptible to insect injury and serious outbreaks seldom occur.
However, the sugar maple borer (Glycobius speciosus), considered to be the most
serious insect enemy of sugar maple.
Pictures
The striking fall foliage of sugar
maple Sugar maples turn brilliant
colors in autumn
The leaves change colors Pails
are hung up from sugar maples to collect sap
References
Laskey, Kathryn. Sugaring time. New York:
Macmillan, c 1983.
Academic American Encyclopedia, volume 13. Grohier Incorporated; Danbury,
Connecticut, 1987.
The New Encyclopaedia Britannica. 15th edition; Chicago: Encyclopaedia Britannica,
1993. volume 7.
Silvics of Forest Trees of the United States. Agriculture Handbook No. 271. Forest
Service; United States Department of Agriculture: Washington, D.C. 20250, 1965.
Other sites
The
Right Tree handbook
http://bluehen.ags.udel.edu
http://plants.usda.gov/plants/
This page was written by Rayan Hourani
for Bio 141, Botany, Fall 1998.
  
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