Richard M. Godman, Harry W. Yawney, and Carl H. Tubbs
Sugar maple (Acer saccharum), sometimes called hard maple or rock maple, is one of the largest and more important of the hardwoods. It grows on approximately 12.5 million hectares (31 million acres) or 9 percent of the hardwood land and has a net volume of about 130 million m3 (26 billion fbm) or 6 percent of the hardwood sawtimber volume in the United States. The greatest commercial volumes are presently in Michigan, New York, Maine, Wisconsin, and Pennsylvania (53). In most regions, both the sawtimber and growing stock volumes are increasing, with increased production of saw logs, pulpwood, and more recently, firewood.
Maples are classified in their own family, Aceraceae, or in the larger group, Sapindaceae. See Systematics and Taxonomy.
Maples were an important sweetener and source of winter nutrition for North American natives and early European settlers (see Uses in full entry). Production of maple syrup is a multimillion dollar industry in the U.S. and Canada (NASS 2011).
Sugar maple is widely planted as an ornamental or shade tree. Many cultivars have been developed, with variations in crown shape, height, fall color, leaf shape, and temperature tolerance. It does not tolerate street salt or soil compaction in urban plantings, so is no longer commonly planted as a street tree. Sugar maple is an important timber tree (see Uses).
Sugar maple in North America is sometimes confused with Norway maple (Acer platanoides), an introduced European species that looks similar, but is more resistant to pollution and has fewer insect pests. Norway maple has broader leaves with drooping lobes, and sap from a broken petiole is milky. Norway maple is considered invasive in 20 Northeastern U.S. states (USFS 2011), and in eastern Canada.
Sugar maple is widespread and dominant or codominant in many northern hardwood and mixed mesophytic forests of the eastern United States. It occurs in rich, mesic (moist) woods but also grows in drier upland woods. In 2002, it was one of the 10 most abundant tree species in the U.S. (FIA 2011). Sugar maple is declining in some northeastern forests (such as the Alleghenies), due to its sensitivity to acid rain and other pollution; it may be replaced by opportunistic species in frequently cut or highly disturbed forests (Wikipedia, 2011). In other regions, sugar maple has increased, possibly due to fire suppression (Potter-Witter and Lacksen 1993; MapleInfo.org 2011).
Animals that feed on sugar maple seeds, buds, twigs, and leaves include white-tailed deer, moose, snowshoe hare, red, gray, and flying squirrels, and numerous lepidopteran larvae and aphids. Porcupines consume the bark and can girdle the upper stem. Songbirds and woodpeckers, and cavity nesters nest in sugar maple. The flowers appear to be wind-pollinated, but the early-produced pollen is important for Apis mellifera (honeybees) and other insects.
Florida maple (A. barbatum, including A. floridanum): primarily a species of the Gulf and southeast Atlantic coastal plain, from Texas to North Carolina and Virginia, and up the Mississippi valley as far as Missouri and Illinois.
chalk maple (A. leucoderme): similar in distribution to Florida maple, but not extending into Virginia or up the Mississippi valley.
black maple (A. nigrum): similar in distribution to ‘true’ sugar maple, but somewhat more restricted.
General: Maple Family (Aceraceae). A native tree with a dense, spreading crown, to 25-37(-40) m in height; bark light gray to gray-brown, rough, deeply furrowed, and darker with age. The leaves are deciduous, opposite, long-petioled, blades 5-11 cm long and about as wide, with 5 shallow, blunt or short-pointed lobes, edges coarsely toothed, dark green and glabrous above, whitish and more or less hairy below, turning intensely red, orange, or yellow in fall. The flowers are small, greenish-yellow, in long-stalked, drooping clusters or racemes, each cluster with 8 to 14 flowers. Most trees are either male or female (the species is essentially dioecious), but both kinds of flowers occur on some trees (technically monoecious), sometimes segregated on different branches. The fruits are winged nutlets (samaras) in a pair, 2-2.5 cm long, clustered on long stalks, red to red-brown. The common name refers to the use of the species for making sugar and syrup.
Variation within the species: Closely similar forms of sugar maple have been recognized at various taxonomic ranks – from varieties to subspecies and species. Three of them are now generally recognized as species, but the differences are technical and it is difficult to be sure of the correct identifications of trees sold as “sugar maple” in the southeastern US. Duncan and Duncan (1988) gives a good summary of the distribution and morphology of these species.
Norway maple (Acer platanoides), an introduced European species, is often planted and looks similar to sugar maple, but Norway maple has broader leaves with drooping lobes, and sap from a broken petiole is milky.
Distribution: Sugar maple is widespread in mixed hardwood forests of the eastern United States. It grows from Nova Scotia and New Brunswick westward to Ontario and Manitoba, North Dakota and South Dakota, southward into eastern Kansas into Oklahoma, and southward in the east through New England to Georgia. For current distribution, please consult the Plant Profile page for this species on the PLANTS Web site.
Range and Habitat in Illinois
Regularity: Regularly occurring
Regularity: Regularly occurring
Global Range: Ranges across North America from Maine and eastern Canada to Minnesota and the eastern Dakotas, southward to Mississippi, eastern Texas, and central Oklahoma.
Occurrence in North America
LA ME MA MI MN MO NH NJ NY NC
OH OK PA RI SC SD TN VT VA WV
WI MB NB NS ON QC
and Manitoba, southward through Minnesota, and eastern Kansas into
northeastern Texas . It extends eastward to Georgia and northward
through the Appalachian Mountains into New England [46,68]. Local
populations occur in northwestern South Carolina, northern Georgia, and
northeastern South Dakota . Disjunct populations are known from the
Wichita Mountains of southwestern Oklahoma .
- The native range of sugar maple.
Sugar maple most commonly occurs in rich, mesic woods but also grows in drier upland woods. It often grows in canyons, ravines, valleys, stream terraces, and streambanks, but it is occasionally found on dry rocky hillsides, at 500-1700 meters elevation. It is a dominant or codominant in many northern hardwood and mixed mesophytic forests. Common codominants include beech (Fagus grandifolia), birch (Betula spp.), American basswood (Tilia americana), northern red oak (Quercus rubra), white oak (Quercus alba), and yellow poplar (Liriodendron tulifera), but it also grows with various other hardwood species as well as conifers such as pine, spruce, fir, and eastern hemlock.
In the absence of disturbance, forests of jack pine, eastern white pine, eastern hemlock, yellow birch, or red pine are replaced by sugar maple and American basswood. Because repeated disturbance by fire was common in eastern deciduous forests in pre-settlement times, succession to sugar maple-American basswood stands may have taken as long as 650 years in some locations. Increases in sugar maple during the past 50 years in central and Great Lakes hardwood forests have been attributed to fire suppression.
This species flowers in April-June, with fruiting occurring in June-October. Fruits ripen about 12-16 weeks after flowering and begin to fall about 2 weeks after ripening. Leaves generally drop just after seeds have fallen. At the southern edge of the species' range, dead leaves tend to remain on the trees through much of the winter.
Sugar maple is a deciduous tree which reaches 90 to 120 feet (27-37 m)
in height and 30 to 36 inches (76-91 cm) in d.b.h. [30,60]. Extremely
large specimens have reached more than 130 feet (40 m) in height and
more than 5 feet (1.5 m) in d.b.h. . Sugar maple is long-lived and
plants can survive for 300 to 400 years . The bark is light gray to
gray-brown and becomes deeply furrowed and rough with age . Twigs
are a shiny, reddish-brown . Sugar maple is relatively deep-rooted,
with many extensively-branched laterals [30,36].
Sugar maple is monoecious or dioecious . Small, greenish-yellow
flowers are borne in tassellike clusters or racemes [9,36,68]. Each
drooping cluster contains 8 to 14 flowers [9,68]. Fruit is a paired,
papery-winged samara which averages 1 inch (2.5 cm) in length [30,32].
Range and Habitat in Illinois
Sugar maple most commonly occurs in rich, mesic woods but also grows in
drier upland woods [18,68]. It grows in level areas or in coves and
other sheltered locations on adjacent lower slopes [1,18,24]. Sugar
maple is often associated with stream terraces, streambanks, valleys,
canyons, ravines, and wooded natural levees [1,10,28,68]. It is
occasionally found on dry rocky hillsides . At the western edge of
its range, sugar maple grows as scattered canopy seed trees or as
abundant seedlings in protected ravines and relatively mesic
north-facing slopes .
Sugar maple is a major species in seven SAF cover types and is common in
17 others . It is a prominent component of mesic hardwood forests,
Great Lakes pine forests, spruce-fir forests, and northern hardwood
forests [12,22,67]. Sugar maple forms pure stands but also grows mixed
with other hardwoods and scattered conifers . Common associates
include American basswood, yellow birch (Betula alleghaniensis), black
cherry (Prunus serotina), red spruce (Picea rubens), white spruce (P.
glauca), beech, eastern white pine (Pinus strobus), eastern hemlock
(Tsuga canadensis), northern red oak (Quercus rubra), white oak (Q.
alba), and yellow-poplar (Liriodendron tulipifera) .
Understory associates: Understory associates of sugar maple are both
varied and numerous. Common shrub associates include beaked hazel
(Corylus cornuta), Atlantic leatherwood (Dirca palustris), redberry
elder (Sambucus pubens), alternate-leaf dogwood (Cornus alternifolia),
dwarf bush-honeysuckle (Diervilla lonicera), Canada yew (Taxus
canadensis), red raspberry (Rubus idaeus), and blackberries (Rubus
spp.). Springbeauty (Claytonia caroliniana), large-flowered trillium
(Trillium grandiflorum), anemone (Anemone spp.) marsh blue violet (Viola
cucullata), downy yellow violet (V. pubescens), Solomon's-seal
(Polygonatum pubescens), false Solomon's-seal (Smilacina stellata), sweet
cicely (Osmorhiza spp.), adderstongue (Ophioglossom vulgatum),
jack-in-the-pulpit (Arisaema atrorubens), clubmosses (Lycopodium spp.),
and largeleaf aster (Aster macrophyllus) .
Soils: Sugar maple can grow on a wide variety of soils [30,75], but
typically grows best on deep, moist, fertile, well-drained soils [4,36].
It grows on sand, loamy sand, sandy loam, silty loam, and loam .
Sugar maple is commonly associated with alluvial or calcareous soils
[24,32] but also grows on stabilized dunes . This tree is
intolerant of flooded soils  and generally grows poorly on dry,
shallow soils . In parts of New England, sugar maple commonly grows
on soils rich in organics . Sugar maple occurs on strongly acidic
(pH=3.7) to slightly alkaline (pH=7.3) soils but grows best where soil
pH ranges from 5.5 to 7.3. Soils are derived from a variety of parent
materials including shale, limestone, and sandstone [68,62].
Elevation: In the southern and southwestern portions of its range,
sugar maple generally grows at intermediate elevations .
Generalized elevational ranges by geographic location are as follows
s Appalachian Mtns. 3,000 to 5,500 feet (910-1,680 m)
Lake States up to 1,600 feet (490 m)
n New England up to 2,500 feet (760 m)
New York up to 2,500 feet (760 m)
Key Plant Community Associations
Sugar maple grows in a wide variety of plant communities throughout
eastern North America. It is a dominant or codominant in many northern
hardwood and mixed mesophytic communities. Common codominants include
beech (Fagus grandifolia), birch (Betula spp.), and American basswood
(Tilia americana). Sugar maple has been listed as a dominant or
indicator in the following community type (cts), ecosystem associations
(eas), dominance types (dts), and plant association (pas)
Area Classification Authority
s IL forest cts Fralish 1976
e IA forest dts Cahayla-Wynne & Glenn-
MI forest eas Pregitzer & Ramm 1984
MN forest cts Daubenmire 1936
s NY forest pas Wilm 1936
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
1 Jack pine
5 Balsam fir
17 Pin cherry
19 Gray birch - red maple
20 White pine - northern red oak - red maple
21 Eastern white pine
22 White pine - hemlock
23 Eastern hemlock
24 Hemlock - yellow birch
25 Sugar maple - beech - yellow birch
26 Sugar maple - basswood
28 Black cherry - maple
30 Red spruce - yellow birch
31 Red spruce - sugar maple - beech
32 Red spruce
33 Red spruce - balsam fir
34 Red spruce - Fraser fir
35 Paper birch - red spruce - balsam fir
40 Post oak - blackjack oak
44 Chestnut oak
51 White pine - chestnut oak
52 White oak - black oak - northern red oak
53 White oak
55 Northern red oak
58 Yellow-poplar - eastern hemlock
59 Yellow-poplar - white oak - northern red oak
60 Beech - sugar maple
61 River birch - sycamore
64 Sassafras - persimmon
107 White spruce
108 Red maple
110 Black oak
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K093 Great Lakes spruce - fir forest
K095 Great Lakes pine forest
K096 Northeastern spruce - fir forest
K097 Southeastern spruce - fir forest
K098 Northern floodplain forest
K099 Maple - basswood forest
K100 Oak - hickory forest
K102 Beech - maple forest
K103 Mixed mesophytic forest
K104 Appalachian oak forest
K106 Northern hardwoods
K107 Northern hardwoods - fir forest
K108 Northern hardwoods - spruce forest
K109 Transition between K104 and K106
K110 Northeastern oak - pine forest
K111 Oak - hickory - pine forest
K112 Southern mixed forest
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES10 White - red - jack pine
FRES11 Spruce - fir
FRES13 Loblolly - shortleaf pine
FRES15 Oak - hickory
FRES16 Oak - gum - cypress
FRES17 Elm - ash - cottonwood
FRES18 Maple - beech - birch
FRES19 Aspen - birch
Soils and Topography
Sugar maple grows on sands, loamy sands, sandy loams, loams, and silt loams but it does best on well-drained loams (30). It does not grow well on dry, shallow soils and is rarely, if ever, found in swamps (30). Sugar maple is soil-site specific in southerly regions but abundant on a wide variety of soils in the northern Lake States. It is mostly found on Spodosols, Alfisols, and Mollisols among the soil orders. In New Hampshire, sugar maple is associated with sites that have abundant organic matter (69), and in West Virginia it is most abundant on areas with high oak site indices (107).
Sugar maple grows on soils ranging from strongly acid (pH 3.7) to slightly alkaline (pH 7.3), but it most commonly grows on soils with a pH of from 5.5 to 7.3 (30). The heavy leaf litter typical of sugar maple tends to modify the pH and nutrient status of the soil. The leaves contain 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
leaves ranges from 4.0 to 4.9. The calcium content remains relatively uniform in trees growing with a pH range of 4.5 to 7.0 but drops as the soils become more acid (5). In the Lake States, sugar maple is found at elevations up to 490 m (1,600 ft)-most commonly on ridges between poorly drained areas and on soil with at least 1 to 1.5 m (3 to 5 ft) to the water table. In northern New England and New York State it grows at elevations up to 760 m (2,500 ft). In the Green Mountains of Vermont and the White Mountains of New Hampshire, especially, the upper limit lies in a sharp horizontal band with a narrow transitional zone into the Boreal forest types. In the southern Appalachians the upper elevation ranges from 910 m (3,000 ft) to 1680 m (5,500 ft), with the lower levels generally restricted to the cooler north slopes. In the southern and southwestern parts of its range, sugar maple more typically grows on moist flats and along ravines at intermediate elevations in the rolling topography.
(80°F), although moisture and aspect influence these extremes. In the sugar maple region, typical ranges in temperatures are from -40° C (-40° F) in the north to 38° C (100° F) in the southwestern areas. Occasional extremes may be more than 11 C (20° F) lower or higher than these.
Precipitation averages range from about 510 mm (20 in) annually near the western edge of the range to 2030 mm (80 in) in the southern Appalachians. Much of the northeastern region receives about 1270 mm (50 in) per year where substantial commercial volumes of sugar maple are located. In general, the growing season precipitation is well distributed and averages 380 mm (15 in) in the western areas and 1020 mm (40 in) in the East. Snowfall often exceeds 2540 mm (100 in) in the northern portion of the range.
In the broad geographic area covered by sugar maple, the growing season ranges from 80 to 260 days. The last killing frost usually occurs from March 20 to June 15 and the first killing frost occurs between September 1 and November 10. In mountainous areas of the Northeast, climatic factors largely determine the upper elevation limits of the species(97).
Minimum seed-bearing age for sugar maple is 30-40 years; maximum seed production is reached after about 60 years of age. Seed is abundantly produced each year but peaks occur mostly from 2-5 years. Seeds are dispersed in fall and germinate in spring. Germination occurs on moist mineral soil or in the litter layer, at an optimal temperature of about 1 C. Seeds can remain viable for up to 5 years but few persist in the seed bank for more than one year. Sugar maple seeds require moist stratification at temperatures slightly above freezing for 35-90 days.
Sugar maple is shade-tolerant but seedlings in dense young stands may survive for only 5 years; those in older stands commonly persist for many years. Such a bank of abundant seedlings and saplings can remain suppressed until gaps are created by windfall or other disturbances, where they typically respond vigorously and rapidly to release. Sugar maples can live for up to 500 years.
Stump sprouting and root sprouting are moderately common means of vegetative reproduction after mechanical disturbance in natural conditions, especially in the northern part of its range, and layering occasionally occurs.
Sap-Visiting Insects of Sugar Maple in Illinois
(Insects suck oozing sap; the flowers of Sugar Maple are wind-pollinated; observations are from Robertson)
Apidae (Apinae): Apis mellifera fq
Andrenidae (Andreninae): Andrena rugosa
Braconidae: Earinus limitaris
Tenthredinidae: Dolerus sericeus
Syrphidae: Helophilus fasciatus, Syrphus ribesii; Tachinidae: Gonia capitata fq; Sarcophagidae: Ravinia derelicta; Calliphoridae: Calliphora vicina, Calliphora vomitoria, Cynomya cadaverina, Lucilia illustris; Muscidae: Helina rufitibia fq, Hydrotaea houghi, Muscina levida, Neomyia cornicina; Aulacigastridae: Aulacigaster leucopeza; Scathophagidae: Scathophaga furcata fq; Piophilidae: Prochyliza xanthostoma fq
Nymphalidae: Nymphalis antiopa, Polygonia comma, Vanessa atalanta
Associated Forest Cover
Sugar maple is a major component in the following types:
27 Sugar Maple
26 Sugar Maple-Basswood
25 Sugar Maple-Beech-Yellow Birch
60 Beech-Sugar Maple
28 Black Cherry-Maple
31 Red Spruce-Sugar Maple-Beech
16 Aspen (Canadian subtype)
Sugar maple is a common associate in the following types:
17 Pin Cherry
32 Red Spruce
30 Red Spruce-Yellow Birch
35 Paper Birch-Red Spruce-Balsam Fir
21 Eastern White Pine
22 White Pine-Hemlock
23 Eastern Hemlock
20 White Pine-Northern Red Oak-Red Maple
24 Hemlock-Yellow Birch
19 Gray Birch-Red Maple
55 Northern Red Oak
58 Yellow-Poplar-Eastern Hemlock
59 Yellow-Poplar-white Oak-Northern Red Oak
It occurs as an infrequent species in Jack Pine(Type 1), Balsam Fir (Type 5), Aspen (Type 16), Red Spruce-Balsam Fir (Type 33), Red Spruce-Fraser Fir(Type 34), Chestnut Oak (Type 44), Pitch Pine (Type 45), White Pine-Chestnut Oak (Type 51), White Oak-Black Oak-Northern Red Oak (Type 52), and River Birch-Sycamore (Type 61).
Large numbers of shrubs are found with sugar maple because of its varied altitudinal distribution. The most common within the commercial range are beaked hazel (Corylus cornuta), Atlantic leatherwood (Dirca palustris), redberry elder (Sambucus pubens), American elder (S. canadensis), alternate-leaf dogwood (Corn us alternifolia), dwarf bush-honeysuckle (Diervilla lonicera), Canada yew (Taxus canadensis), red raspberry (Rubus idaeus), and blackberries (Rubus spp.). Common flowering plants include springbeauty (Claytonia caroliniana), large-flowered trillium (Thulium grandiflorum), anemone (Anemone spp.), marsh blue violet (Viola cucullata), downy yellow violet (V. pubescens), Solomons-seal (Polygonatum pubescens), false Solomons-seal (Smilacina stellata), sweet cicely (Osmorhiza spp.), adderstongue (Ophioglossom vulgatum), jack-in-the-pulpit (Arisaema atrorubens), clubmosses (Lycopodium spp.), and largeleaf aster (Aster macrophyllus).
Diseases and Parasites
At least two species of bud miners, Proteoteras moffatiana and Obrussa ochrefasciella, overwinter in the terminal bud of sugar maple and kill it. This causes repeated forking, which reduces merchantable log length and adds to the risk of crown loss from splitting. Other bud-damaging insects that may also cause forks are Choristoneura rosaceana, Cenopis pettitana, Phyllobius oblongus, and Platycerus virescens (65,66,7798,123).
Forking at the terminal bud occurs in trees of all ages but is especially pronounced in overstory trees. Side crowding and overhead shading help correct lower forking (32). But early or heavy thinning sets the fork and causes shorter merchantable lengths. As fork members increase in size and weight, fork breakage also increases.
Except for bud losses, sugar maple is not highly susceptible to insect injury and serious outbreaks are not common (62). The most common insects to attack sugar maple are defoliators and these include the gypsy moth (Lymantria dispar), forest tent caterpillar (Malacosoma disstria), linden looper (Erannis tiliaria), fall cankerworm (Alsophila pometaria), spring cankerworm (Paleacrita vernata), green-striped mapleworm (Anisota rubicunda), Bruce span-worm (Operophtera bruceata), maple leaf-cutter (Paraclemensia acerifoliella), maple trumpet skeletonizer (Epinotia aceriella), and saddled prominent (Heterocampa guttivitta).
One insect of the genus Phytobia occasionally causes pith flecks that seriously degrade veneer logs. This insect tunnels the full length of the cambium layer and exits near the root collar (117).
Borers that attack sugar maple include the carpenterworm (Prionoxystus robiniae), sugar maple borer (Glycobius speciosus), maple callus borer (Synanthedon acerni), and occasionally horntajls (Xiphydria abdominalis and X. maculata) (95).
Sucking insects that affect sugar maple include the woolly alder aphid (Prociphilus tesselatus) and other aphid species (Neoprociphilus aceris and Periphyllus lyropictus) which injure leaves and reduce growth.
Of the scale insects, the maple phenacoccus (Phenacoccus acericola), is the most important to sugar maple. The maple leaf scale (Pulvinaria acericola) and the gloomy scale (Melanaspis tenebricosa) also frequently attack sugar maple.
Many sugar maple trees died in a small area of Wisconsin and Michigan in 1957 (113). Certain insects-the leaf rollers (Sparganothis acerivorana and Acleris chalybeana) and the maple webworm (Tetralopha asperatel1a)combined with disease and climatic factors were thought to be the cause of this mortality (44,48,61,120). The decline has abated but appears to have recurred with less severity on a portion of the same area in the late 1970's.
Diseases of sugar maple generally deform, discolor, or decrease volume but seldom kill the tree (80). The two most important diseases in managed second-growth are probably Eutypella (Eutypella parasitica) and Nectria (Nectria galligena) cankers. In the Lake States these cankers each affect from about 1 to 4 percent of the trees (77) but in Ontario they occur more frequently (60,87). Nectria canker is more prevalent following shelterwood cuttings, probably because conditions favorable for infection are established (2). Two other cankers (Schizoxylon micro sporum and Hypoxylon lilakei) occur rarely on sugar maple. In a few instances cankers may kill a tree but generally only predispose it to breakage.
Some common fungi-causing heart rots in sugar maple are Armillaria mellea, primarily a root-rotting fungus; Hydnum septentrionale, which causes a soft, spongy, white heart rot; Inonotus glomeratus, which causes white to light brown spongy heart rot; and Ustulina vulgaris, which causes a butt rot (30).
The amount of defect in sugar maple trees in virgin and unmanaged stands is usually high-commonly from 35 to 50 percent (30). Defect resulting from logging damage usually is minor in small wounds for as long as 10 years, but 20-cm (8-in) scars all were infected within 20 years and value losses were significant (47,81).
Logging injuries to the stems of residual trees and to reproduction frequently result in the entrance of decay and eventually serious volume loss (6,79). In a study in Upper Michigan at least 30 percent of the logging scars on the main stem of older trees resulted in serious defects within 15 to 20 years (30). Larger limbs broken in logging also usually result in serious defects (93,94). In Upper Michigan after a 20-year period about 8 percent cull resulted from decay and stain that had entered through scars on limbs 10 cm (4 in) and larger (30). Smaller limb breakage exposing only sapwood, however, generally results in little volume loss (4,30).
Two wilts occasionally attack and kill sugar maple. Sapstreak, caused by Ceratocystis coerulenscens, enters through root injuries from logging and has been reported in several localities (56,57,80). Verticillium wilt, caused by Verticillium albo-atrum, is usually found only in shade trees. This wilt also invades the trees through the roots.
When stored for more than a year, a saprophytic fungus, Cryptostroma corticale, sometimes develops on the bark of sugar maple. The spores from this fungus are released during processing and have caused bronchial asthma and severe allergenic lung disorders to millworkers (83,84).
Physical and climatic injuries often occur on sugar maple. Much damage from glaze storms occurred in New York in 1942. The injured trees showed a slight tendency to sprout and renew growth. Many of the smaller trees that had 85 percent or more of their crown broken away developed saprot (30).
Winter sunscald frequently occurs in even-aged sugar maple stands. Trees are damaged from late winter heating of the bole above the snowline on bright sunny days followed by rapid freezing that ruptures the cells. Most injury occurs when the stems are 2.5 to 7.6 cm (1 to 3 in) in d.b.h., and certain topographic positions are affected more than others (55). Healing in dense stands is slow, if at all, and later stages often appear to be a simple frost crack. Various fungi may be present but may or may not prevent closure (59). Part of the lack of closure may be due to shrinkage and swelling of the bole associated with changes in air temperature (35).
In some areas the lower portion of sugar maple boles contains many vertical cracks from 2.5 to 7.6 cm (1 to 3 in) long. Although these cracks have been termed annual maple cankers, the causal agent does not seem to be a fungus. These cankers slowly disappear and new ones recur at short intervals (32). In Pennsylvania they were most common on slowly permeable soils (116) but no specific cause has been identified (3,58).
Sugar maple can be severely damaged from deicing road salt (96). In an industrial area the number of overstory sugar maples was markedly reduced from exposure to sulfur oxides, nitrogen oxides, chlorides, and fluorides. Sugar maple remained an abundant species in the understory because of a lower exposure level (72).
Numerous animals feed on or injure sugar maple without serious effect except in local and limited situations. Deer browsing is probably the most common wildlife factor. Winter browsing in the Lake States causes little damage or reduced growth (51,100). In the central Adirondacks, however, continual browsing of sugar maple allows American beech, which the deer avoid, to dominate northern hardwood understories (54).
Red, grey, and flying squirrels sometimes gnaw or feed on the seed, buds, foliage, and twigs of sugar maple. In rare instances, they have girdled and killed larger branches and tree tops (30,100). Porcupines may feed on the bark and kill the top by girdling the upper stem (8,30).
Sapsuckers frequently peck and cause degrade in some sugar maple trees but rarely, if ever, kill the tree (19,82,90,92). On heavily pecked trees in the spring a fungus develops on the sap and causes the bark to turn black (82). Such trees probably should be retained in the stand to prevent other trees from being attacked.
Number of Occurrences
Note: For many non-migratory species, occurrences are roughly equivalent to populations.
Estimated Number of Occurrences: > 300
Comments: Widespread and abundant in the eastern and midwestern United States, into southern Canada. While essentially continuous in large areas (at least before fragmentation due to agriculture and development), the main range can be considered to include many hundreds of reasonably independent, self-maintaining stands. Nevertheless, genetic mixing by storm-blown pollen and seeds lead to metapopulation dynamics within aggregations of such areas. There are also a number of outlying stands that can be considered occurrences as well.
Fire Management Considerations
collected in two Michigan counties was documented as follows :
Wexford Co. Ingham Co.
Fall 7.1 8.5
Spring 9.2 12.2
Early summer 10.3 13.1
Broad-scale Impacts of Plant Response to Fire
The Research Project Summaries Effects of surface fires in a mixed red and
eastern white pine stand in Michigan and Early postfire effects of a prescribed
fire in the southern Appalachians of North Carolina, and the Research Paper by Bowles and others 2007 provide information on prescribed fire and postfire response
of several plant species, including sugar maple, that was not available when this
species review was originally written.
Plant Response to Fire
top-killed by fire do not sprout, small saplings occasionally sucker
. Although sprouting is common in young sugar maples following
mechanical disturbances, it is relatively uncommon after fire. Sugar
maple reestablishes through seedling sprouts and seedlings .
Immediate Effect of Fire
Sugar maple is sensitive to fire . The thin bark is easily damaged
by even light ground fires . Curtis  reported that "cambial
injury occurs even in trees that show little external damage." Large
trees occasionally survive light fires and may exhibit visible fire
scars . Hot fires can kill existing regeneration .
Sugar maple commonly occurs in mesic closed canopy forests that are
relatively resistant to ground fires, particularly during the winter and
spring when litter is usually moist . In the summer, flammable
litter (generally deciduous leaves) is often scarce or absent. Greatest
fire hazard occurs in dry years during October, after the leaves have
fallen . Fires which occur during this time period are occasionally
severe and can kill the entire stand. In a Tennessee loblolly pine
stand, DeBruyn and Buckner  reported 85 percent mortality in sugar
maple following a fall burn when fuels were very dry.
survivor species; on-site surviving root crown or caudex
off-site colonizer; seed carried by wind; postfire yrs 1 and 2
Sugar maple typically increases in the absence of fire . Seedlings
occasionally sprout, but postfire establishment occurs primarily through
an abundance of wind-dispersed seed.
Central States: Fire has played an important role in deciduous forests
of the central and eastern United States [63,76]. Fire suppression has
favored sugar maple and other northern hardwood species, while
fire-tolerant species such as white oak, northern red oak, and Shumard
oak (Quercus shumardii) have experienced declines . Dramatic
increases in sugar maple during the past 48 years in central hardwood
forests have been attributed to fire suppression . Sugar maple was
formerly nearly absent in areas of central Missouri which bordered the
fire-prone prairies . Since settlement times, it has increased as
mean fire intervals have declined.
The Southeast: Fire was a major influence in presettlement forests of
the Southeast . Increased fire suppression in this region has also
favored shade-tolerant hardwoods, such as sugar maple, and has resulted
in a decrease in oaks .
Northeast: Mean fire intervals are typically long in most northern
hardwood forests. In New England, fire is a less important disturbance
agent than windthrow or insect infestations . In northern hardwood
stands in Maine and New Hampshire, mean fire intervals in presettlement
forests ranged from 230 to 4,970 years . In New Brunswick, fire
rotations have been estimated at 625 years in both sugar maple-yellow
birch-fir and sugar maple-eastern hemlock-pine forests . In
hardwood stands in parts of New Hampshire, sugar maple has been
Great Lakes Region: Northern hardwood forests of the Great Lakes Region
lie between the fire-prone savanna and prairie communities to the south
and west . Fires in these forests were presumably fairly common in
presettlement times but may have occurred at intervals which exceeded
the lifespan of individual trees . Shade-tolerant species, such as
sugar maple, commonly assume dominance in the absence of fire in Great
Lake's hardwood forests. Where fire frequencies are high, aspen and
paper birch (Betula papyrifera) are common dominants . In
presettlement times, sugar maple was typically absent from portions of
the North Woods which burned at frequent intervals .
More info for the term: climax
Sugar maple is very tolerant of shade and can persist for long periods
beneath a dense forest canopy . It is noted for its ability to
quickly occupy gaps created in the forest canopy [37,64]. A bank of
abundant seedlings remains suppressed until gaps are created by windfall
or other disturbances . Seedlings and saplings typically respond
vigorously and rapidly to release and can overtop competitors such as
northern red oak. Openings or gaps in the canopy allow more nutrients,
light, and water to become available . In many areas, sugar maple
is a dominant species in gaps created by dying American elms .
Sugar maple is generally regarded as a late seral or climax species in
many eastern deciduous forests . However, as Parker and Sherwood
 note, the "long-term dynamics of eastern deciduous forests are not
well understood." Throughout much of the Upper Midwest, sugar maple
codominates climax stands with American basswood, or yellow birch
[4,13,23]. In the absence of disturbance, forests composed of jack
pine, eastern white pine, eastern hemlock, yellow birch, or red pine are
replaced by sugar maple and American basswood [12,21,69]. However, it
should be noted that disturbances, particularly fire, were common in
eastern deciduous forests in presettlement times. In some locations,
succession to sugar maple-American basswood stands may have taken as
long as 650 years .
Sugar maple reproduces through seed and by vegetative means.
Seed: Sugar maple possesses extremely effective outbreeding mechanisms
, and flowers are readily wind pollinated . Minimum
seed-bearing age is 30 to 40 years [30,54]. Forty- to sixty-year-old
trees with 8-inch (20 cm) d.b.h. produce light crops, whereas 70- to
100-year-old trees with d.b.h. of 10 to 14 inches (25-36 cm) produce
moderate seed crops . Large fluctuations in annual seed crops have
been reported . Seed production is partly dependent on genetic
factors, and some trees produce an abundance of flowers nearly every
year . In north-central Wisconsin, good or better crops are
produced at 1- to 4-year intervals . Elsewhere in the United
States, good crops occur at 2- to 5-year intervals, and in Canada, at 3-
to 7-year intervals . In good crop years, 264 seeds per meter
square may be produced .
Seed dispersal: Seed is primarily dispersed by wind , which can
carry the relatively large seeds for up to 330 feet (100 m) .
However, most seeds do not travel more than 49 feet (15 m) from the
forest edge . Some sugar maple seed may also be dispersed by water
Seed banking: Sugar maple seed can remain viable for up to 5 years when
properly stored . However, few seeds persist in the seed bank for
more than 1 year , and sugar maple is not considered an important
seed banker .
Seedling establishment: Seedling recruitment varies annually; periodic
high seedling densities may function as a predator avoidance mechanism
. In favorable years seedling recruitment may reach 18.7 seedlings
per meter square, but in poor years no seedling recruitment occurs .
Seedlings can survive for long periods when suppressed beneath a forest
canopy and respond quickly to release. Seedlings in very dense young
stands may survive for only 5 years, but in stands where trees average
10 inches (25 cm) or more in d.b.h., seedlings commonly persist for many
years. Initial seedling growth is slow , and mortality is often
Vegetative regeneration: Sugar maple is a prolific sprouter in the
northern part of its range, but at the southern edge of its range, it
sprouts less vigorously than associated hardwoods . Stump-sprouting
and root-sprouting are moderately common . Layering occasionally
Growth Form (according to Raunkiær Life-form classification)
More info for the terms: chamaephyte, geophyte, hemicryptophyte, phanerophyte
Undisturbed State: Phanerophyte (mesophanerophyte)
Undisturbed State: Phanerophyte (megaphanerophyte)
Burned or Clipped State: Chamaephyte
Burned or Clipped State: Hemicryptophyte
Burned or Clipped State: Cryptophyte (geophyte)
Reaction to Competition
Release is seldom justifiable for young sugar maple stands subjected to suppression from scattered dominant trees or pin cherry (Prunus pensylvanica) because the sugar maple will overcome suppression under those conditions (30). Release is needed, however, when sugar maple competes with striped maple (Acer pensylvanicum), black cherry (Prunus serotina), yellow-poplar (Liriodendron tulipifera), and the oaks (Quercus spp.), because growth is retarded and survival is reduced by such competition (107).
One sapling stand study showed that unreleased, dominant trees of good vigor averaged 23 mm (0.9 in) in diameter growth and heavily released trees averaged 46 mm (1.8 in) in diameter growth per year during a 7-year period; unreleased, codominant trees of good vigor averaged 18 mm (0.7 in) in diameter growth and heavily released trees 38 mm (1.5 in). Pole-size trees also respond well to release (31,102).
If released too much, sugar maple readily develops epicormic sprouts from dormant buds (14,31,33, 36,78). Gradual release and good crown development provide adequate control over epicormic sprouting and also enhance natural pruning of epicormic branches on the lower bole. Consequently, proper thinning at scheduled intervals is necessary to encourage quality improvement as well as diameter growth.
Although some root growth may continue throughout the year if the soil does not freeze, the bulk of the new root regeneration depends on growth factors exported from physiologically nondormant buds. In northern races of sugar maple, about 2,500 hours of continuous chilling are required to break bud dormancy (64).
Sugar maple roots are extremely sensitive to flooding during the growing season. The roots of maple form both endotrophic and ectotrophic mycorrhizae.
Animals that feed on sugar maple seeds, buds, twigs, and leaves include white-tailed deer, moose, snowshoe hare, red, gray, and flying squirrels, and numerous lepidopteran larvae and aphids. Porcupines consume the bark and can girdle the upper stem. Songbirds and woodpeckers, and cavity nesters nest in sugar maple. The flowers appear to be wind-pollinated, but the early-produced pollen is important for Apis mellifera (honeybees) and other insects.
Life History and Behavior
More info for the term: association
Growth initiation of sugar maple varies geographically . Flower
buds generally begin to swell prior to the development of vegetative
buds and generally emerge 1 to 2 weeks before the leaves appear .
Male and female flowers mature at slightly different rates, which
promotes cross-pollination . Fruit ripens approximately 12 to 16
weeks after the flowers appear [30,70]. Fruit begins to fall
approximately 2 weeks after ripening . Flowering and fruiting dates
by geographic location are as follows:
Location Flowering Fruiting Authority
Adirondack Mtns. May Sept.-Oct. Chapman & Bessette 1990
Blue Ridge Mtns. April-June ---- Wofford 1989
FL Panhandle March ---- Clewell 1985
Great Plains April-May ---- Great Plains Flora
Gulf & Atlantic April - May ---- Duncan & Duncan 1987
New England April 28-May 1-23 ---- Seymour 1985
NC, SC April - May June - Oct. Radford & others 1968
se US March - May ---- Duncan & Duncan 1988
Leaves turn yellow to orange or deep red in the fall  and generally
drop just after seeds have fallen . At the southern edge of the
species' range, dead brown leaves tend to remain on the trees through
much of the winter . Trees from the northern portion of the
species' range become dormant earlier than do those from the South .
In older stands, the percentage of stumps sprouting decreases with increase in tree size, stand density, and years since cutting. Two years after a cutting in northern Michigan, the most sprouting occurred on 15-cm (6-in) trees and the least sprouting on 76-cm (30-in) trees. The percent of stumps sprouting averaged 94 and 38, respectively. Five years after cutting, the percent of sprouting dropped to about 58 and 6, respectively. The number of sprouts per stump also declined with years since cutting (30). Sugar maple is a prolific sprouter in the North, but it sprouts less than other hardwood species in the southern part of its range (9,86,88,99).
Cuttings of sugar maple can be rooted but may later fail due to poor overwintering survival. Cuttings can be successfully overwintered by forcing the cutting to break bud and produce a flush of new growth immediately after it roots with the use of gibberellic acid (128). Rooting response varies greatly between clones-differences range from 0 to 100 percent, and rooting response tends to be consistent from year to year. Timing the collection of cuttings is critical; those taken in mid-June generally give the best results. A rooting medium consisting of a 1 to 1 mixture of perlite and sphagnum moss, with intermittent misting, has worked well with sugar maple cuttings. The reliability of cuttings to propagate trees with figured wood, such as curly grain and bird's-eye, has not been verified (30).
Sugar maple trees with desirable genetic characteristics can be reproduced by grafting. Success with this method can be highly variable depending to a large degree on grafting techniques, that is, when and under what conditions the scions were collected and handled, treatment of the rootstock, and experience of the grafters (129). Of the various methods available, bud grafting is used most commonly and with a high degree of success by commercial nurserymen (64).
Air-layering, a method of propagation that stimulates root development on branches still attached to the parent tree, is another method that has been successfully used (16). A major disadvantage of this procedure is that branches on some trees selected for propagation may not be readily accessible.
Sugar maple roots release an exudate that can inhibit the growth of yellow birch when the root growth periods coincide, thus gaining a growth advantage over one of its associated species (110). Other tree species may be similarly affected. Aster and goldenrod exert an allelopathic effect on sugar maple by reducing germination and early growth of seedlings (24).
The growth of understory seedlings begins before the overstory leafs out, generally about mid-May in Upper Michigan. About 90 percent of the seasonal height growth occurs within 18 days under dense stands and 24 days in the open (50). The major growth of other species studied extended about three times longer.
Seedling numbers greater than 370,500/ha (150,000/acre) are common, although as many as 50 percent of the new seedlings may not survive the first year. Seedlings in the understory of young, dense stands may not survive for more than 5 years but many of the seedlings under stands averaging 25 cm (10 in) d.b.h. or more will persist, although they will have little annual height growth until released. In a study of reproduction in old growth stands cut to various basal area densities, number of seedlings per hectare did not differ significantly at either 2 or 5 years after cutting. After 10 years, seedlings under the lightest overstories (6.9 m²/ha or 30 ft²/acre) grew most rapidly although seedlings were abundant under all overstory densities (109).
In the drier Lake States region, natural seedlings must have overstory shade for survival until they reach 0.6 to 1.2 m (2 to 4 ft) in height, at which time their root systems have developed from the litter-mineral soil interface into mineral soil. The entire overstory can then be removed with high seedling survival and full stocking (42). Removing the over-story before seedlings are established usually results in semipermanent wildlife openings in the Lake States (112). In partially cut stands, the tallest seedlings usually develop and constitute the trees of the new stand as the overstory is gradually removed(78).
Planting or other special regenerative measures are rarely needed for sugar maple in New England or the Lake States where the tree grows naturally. In other regions, sugar maple is less aggressive and planting is a desirable practice. Nursery stock used in planting is usually fall sown at a depth of about 6 mm (0.25 in) and covered with about 6 mm (0.25 in) of sawdust. The nursery bed is covered by about 50 percent lath shade. Sowing density should yield about 130 to 160 seedlings per square meter (12 to 15 seedlings/ft²) and seedlings should be vertically root pruned before lifting, usually as 2-0 stock (101,121,124). On more difficult sites 3-0 stock is preferred with tops averaging about 25 cm (10 in) or about twice the height of 2-0 seedlings (101).
Open field plantings with sugar maple have a high survival rate, but seedlings grow poorly because of their inability to compete for moisture and nutrients with herbaceous vegetation. Generally, open field plantings require good stock and several years of site maintenance to assure success (114,127). Time of planting is important. Survival and growth can be vastly improved by planting very early in the spring compared to planting late in the spring. The increase is attributed to the greater root regeneration capabilities during that time (118). Fall plantings have been highly successful in Vermont (127). Sugar maple must be planted at relatively close spacings in order to correct the forking problems that result from the frequent loss of the terminal bud in this opposite-branched species (78,89).
Seed Production and Dissemination
Light fruit crops are produced by 40- to 60-year-old trees with 20 cm (8 in) d.b.h., and moderate crops by 70- to 100-year-old trees with 25- to 36-cm (10- to14-in) d.b.h. Saw-log-size trees produce vast numbers of samaras. During an excellent fruiting year in northern Michigan, a series of traps caught 22 million/ha (8.56 million/acre) sugar maple samaras in a virgin stand and 11 million/ha (4.3 million/acre) in a selectively cut stand (30).
Based on 32 years of observation in northcentral Wisconsin, good or better fruit crops occurred about 44 percent of the years, the lowest percentage among the major hardwood species of the area (37;40). Good or better fruit crops occurred as often as 4 successive years, but successive poor crops did not extend longer than 2 years. The period between good or better crops ranges from 1 to 4 years in north-central Wisconsin, from 2 to 5 years in other portions of the United States, and from 3 to 7 years in Canada(30,47; 115).
To germinate, sugar maple seeds require moist stratification at temperatures slightly above freezing for 35 to 90 days. Each sugar maple seed seems to have its own stratification-period threshold, short of which the epigeal germination process ceases (126). Both moisture content and temperature affect how long seeds can be stored. Under proper conditions seeds have been stored for at least 5 years without loss of viability (10). In natural stands, few if any seeds remain viable on the forest floor beyond the first year (73).
Sugar maple seed has an extremely high germination capacity, with averages of 95 percent or more (126). The optimum temperature for germination is about 1° C (34° F), the lowest of any known forest species (39,108). Germination drops rapidly as temperatures increase, and little if any germination occurs above 10° C (50° F). Rapid warming of the surface soil in the spring of 1978 in northern Wisconsin, for example, prevented germination from the bumper seed crop of 1977, except in a few remaining snowbanks along the roads (38). Under natural conditions the cotyledon leaves are out and growing before the snow is gone in the northern regions. This unique characteristic of germination at low temperatures probably accounts for the abundance of sugar maple regeneration under most stand conditions in the north. Another major characteristic of the germinating sugar maple seed is its vigorous development of a strong radicle that has the strength and length to penetrate heavy leaf litter and reach mineral soil during the moist period.
Flowering and Fruiting
Flowering in sugar maple is polygamous, occurring over the entire crown. The long-pedicelled, apetalous yellow flowers, about 6.4 cm (2.5 in) long, seem to be perfect, but usually only one sex is functional within each flower. Both sexes are typically produced in the upper part of the crown but only males form in the lower part (26). In some trees, certain major limbs produce only male and others only female flowers. The flowers of sugar maple were thought to be bee-pollinated (30,64), but a recent study showed that pollination occurs freely in sugar maple without the aid of insects (28).
The fruit, a double samara, ripens in about 16 weeks. Usually only one of the paired samaras is filled with a single seed, typically averaging 7 to 9 mm (0.3 to 0.4 in) in length, but occasionally both samaras will contain seed or both will be empty. Some trees produce triple samaras and others produce samaras with double wings. Samaras collected from trees having the bird's-eye wood grain characteristic showed a consistency of overlapping of the wings, a strong union between samaras, and lighter colored wings after drying but these characteristics have not been confirmed as being an attribute associated with bird's-eye (32).
Seeds are mature when the samaras turn yellowish green and have a moisture content less than 145 percent (11,124). The samaras begin falling about 2 weeks after they ripen, usually just before the leaves fall.
Growth and Yield
Growth during the pole stage is slower than for most associated hardwood species. Height and radial growth begins at about the same time as the buds leaf out. Height growth is completed in about 15 weeks and radial growth in from 14 to 17 weeks, depending on the season and locality (30). In some areas, height growth is about 85 percent complete within 5 weeks and cambial growth is about 80 percent complete in 8 weeks (30).
In the Lake States, older sugar maple trees (fig. 3) in a mature stand grew 2.5 cm (1 in) d.b.h. in 10 years (30). Maximum diameter growth rates of individual trees in mature stands in the Upper Peninsula of Michigan were about 7.6 cm (3 in) per decade for 46-cm (18-in) trees, 8.9 cm (3.5 in) for 30-cm (12-in) trees, and 10.2 cm (4 in) for 15-cm (6-in) trees (15). Growth in second-growth stands, however, generally exceeds 5.1 cm (2 in) in 10 years for saw-log-size trees (18) and a maximum rate in excess of 10.2 cm (4 in) has been reported (106). For the first 30 to 40 years, sugar maples average about 30 cm (12 in) a year in height growth.
Mature trees and stands of sugar maple reach 300 to 400 years of age, 27 to 37 m (90 to 120 ft) in height, and 76- to 91-cm (30- to 36-in) in d.b.h. (30). Following repeated cutting under the uneven-aged system, age and diameter show strong linear relation with the older ages, seldom exceeding 250 years (68,111). Height growth usually ceases or becomes negligible at about 140 to 150 years (30). Diameter growth continues at a decreasing rate with age and size. The largest reported sugar maple tree, growing near Kitzmiller, MD, has a d.b.h. of 209 cm (82.1 in), is 23.8 m (78 ft) tall, and has a crown spread of 20.1 m (66 ft) (1).
Yields of mixed hardwood stands, but predominantly sugar maple, range up to a maximum of 216 m3/ha (14,000 gross board feet/acre) (30,70).
Yields for northern hardwood stands in the Lake States are available from estimates of average stand age and average stand diameter (table 1). Both parameters are based on overstory trees. Basal-area stocking of stands commonly ranges from 27.6 to 36.8 m²/ha (120 to 160 ft²/acre). A few older stands exceed 45.9 m²/ha (200 ft²/acre). Even-age and uneven-age silvicultural systems are available for managing stands in which sugar maple is a principal component and a desired species. Periodic annual growth averaging about 4.2 mi/ha (350 fbm/acre) and annual basal-area growth of up to 0.7 m²/ha (3 ft²/acre) is typical of young stands on good sites in the Lake States but varies with total basal-area stocking, distribution of trees by size class, and site (18). Improvement in grade and tree size should be the guiding principle in stand management because this factor contributes more to value increase than diameter growth under most conditions (41,75,105).
Molecular Biology and Genetics
Most of the genetic work in sugar maple is currently confined to improving maple syrup (27) and developing ornamental trees (49,62,119). Nurserymen rely mostly on budding and some grafting for vegetative propagation. Bird's-eye grain trees have been grafted since the early 1960's but results are not available for propagation of this characteristic (63). The USDA Forest Service, in recent work, has selected 228 superior sugar maple trees and established three plantations with 126 families (43).
Hybrids have been reported between sugar maple and black and red maples (30). Hybrid seedlings have been obtained by pollinating sugar maple with another maple (presumably Acer macrophyllum) (30).
Barcode data: Acer saccharum
Statistics of barcoding coverage: Acer saccharum
Public Records: 15
Specimens with Barcodes: 24
Species With Barcodes: 1
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
Reasons: Widespread, abundant tree species of the eastern and midwestern United States, often becoming the dominant or co-dominant tree in the forest canopy over large areas, particularly in the Appalachians and the Midwest.
Environmental Specificity: Broad. Generalist or community with all key requirements common.
Comments: Relatively broad habitat amplitude (although doing best on mesic but not hydric soils), in a wide climatic range over a host of bedrock types, including glaciated areas.
edge of its range .
Please consult the PLANTS Web site and your State Department of Natural Resources for this plant’s current status, such as, state noxious status, and wetland indicator values.
Global Short Term Trend: Relatively stable (=10% change)
Comments: MOre or less stable, with colonization of abandoned farmland or maturing forest lands counterbalancing losses from land clearing for development.
Global Long Term Trend: Decline of 30-50%
Comments: Lost many individuals (and entire stands) to 19th-century agricultural clearing and to continued development in the 20th and early 21st centuries.
Degree of Threat: Low
Comments: Relatively unthreatened. Harvested commercially for its high-quality wood, but generally selectively with younger trees able to fill gaps. Losses due to development (often in forested abandoned farmland) have local impact but do not appear to be eliminating the species from substantial areas.
Damage: Sugar maple is susceptible to wind damage and to damage caused
by ice storms and winter freezes [11,30]. De-icing salts often damage
sugar maples which grow along roadways. Individuals within the
overstory are susceptible to air pollutants such as sulfur oxides,
nitrogen oxides, chlorides, and fluorides . Sugar maple is
susceptible to logging injuries which frequently permit the entrance of
Insects/disease: Sugar maple is host to numerous insects including bud
miners, aphids, borers, and defoliators such as the gypsy moth, tent
caterpillar, linden looper, and cankerworms [2,30]. Cankers, root rot
(Armillaria spp.), and wilt also affect sugar maple. Since the early
1900's, this species has been periodically affected by a condition known
as maple decline . Increases in die-back have been observed in many
parts of the Northeast since 1982 . Causes of maple decline are
unknown, but acid rain and other pollutants are possible contributors
. Trees already weakened by pollutants may be increasingly
susceptible to root rot and tent caterpillar infestations . Maple
decline may be accentuated by a series of unusual climatic events; large
diameter trees are most susceptible .
Silviculture: Past exploitation has resulted in the degradation of many
sugar maple stands . However, in some areas, high-grading of oaks,
hickories, and walnuts, has actually produced a proportional increase in
sugar maple . Shelterwood harvests and progressive strip cut
methods are often applied to mixed hardwood stands which include maple
[31,50]. For best growth of sugar maple, the residual canopy left after
the first shelterwood cut should admit approximately 40 percent light
. A two-cut shelterwood system "cannot guarantee natural
regeneration" in stands which are less than 40 years in age.
Chemical control: In general, sugar maple is resistant to foliar
herbicides . Studies indicate that Tordon may be effective in
controlling sugar maple .
Cultivars, improved and selected materials (and area of origin)
This species is readily available through local nursuries.
Sugar maples are not particularly good street trees, because they are intolerant of compacted soil, high heat, air pollution, and road salt commonly found in urban environments. They are susceptible to stem and root injury, and verticillum wilt may occur when grown in heavy, poorly drained soils. “Maple decline,” periodic die-backs of relatively large trees in the Northeast, has been attributed to acid rain and other air pollutants, particularly in the last two decades, but its exact causes are not understood.
Even light ground fires may damage the thin bark of sugar maple. Hot fires can kill an entire stand and existing regeneration. The trees sprout poorly after fire. Although communities with sugar maple are relatively resistant to ground fires, a fire hazard may occur in dry years during October, after the leaves have fallen.
Seed can propagate sugar maple; early spring plantings generally produce the best results. Nurserymen usually rely on budding or grafting or sometimes use air layering or rooting of stem cuttings. Use stem tips 35-55 centimeters long taken in mid June with fully elongated bottom leaves; rooting occurs in 4-6 weeks under mist in a 2:1:1 mixture of sandy loam, vermiculite, and peat moss.
Relevance to Humans and Ecosystems
Other uses and values
maple syrup industry is important throughout much of eastern North
America and accounted for more than 100 million dollars in trade during
1989 . Maple sugar and syrup were used as trade items by many
Native American peoples . Sugar maple is an attractive shade tree
and is widely planted as an ornamental [42,54]. It is sometimes used in
shelterbelt plantings .
Value for rehabilitation of disturbed sites
It can be propagated by seed, which averages 7,000 per pound (15,400/kg)
. Early spring plantings generally produce the best results .
Sugar maple can also be propagated vegetatively by budding, grafting,
air-layering, or by rooting stem cuttings [30,42].
as the black-capped chickadee excavate nest cavities or utilize
preexisting cavities . The common flicker, pileated woodpecker, and
screech owl also nest in maples .
Importance to Livestock and Wildlife
snowshoe hare [31,53,71]. In Nova Scotia and New Brunswick,
white-tailed deer and snowshoe hare use is heaviest during the winter
. The red squirrel, gray squirrel, and flying squirrels feed on the
seeds, buds, twigs, and leaves of sugar maple . The porcupine
consumes the bark and can, in some instances, girdle the upper stem
Wood Products Value
is well suited for many uses and is commonly used to make furniture,
paneling, flooring, and veneer [18,42]. It is also used for gunstocks,
tool handles, plywood dies, cutting blocks, woodenware, novelty
products, sporting goods, bowling pins, and musical instruments
phenological development . Starch content is highest in early fall
and lowest in winter. Sugar maple leaves average 1.81 percent calcium,
0.25 percent magnesium, 0.75 percent potassium, 0.11 percent phosphorus,
0.67 percent nitrogen, and 11.85 percent ash by dry weight . Unlike
many plants, the leaves of sugar maple typically contain relatively high
levels of calcium, magnesium, and potassium when they are shed in autumn
Samaras are palatable to squirrels and many other small mammals.
Breeding experiments have determined that sugar content is high for certain families and that sugar content in individual trees is consistent over a period of years (64,104). A sugar content of 7.4 percent has been attained by crossing two selected parents of slightly lower content (64). The sugar content is also correlated with the volume yield of sap (7,74).
Sugar maple is the only tree today used for commercial syrup production, as its sap has twice the sugar content of other maple species. The sap, mostly collected in the spring, is concentrated by boiling or reverse osmosis, with about 35-40 liters of sap making 1 liter of syrup. A single tree may produce 5-60 liters of sap per year. Nights below freezing and days at higher than 5°C are needed to ensure good sap flow. Sugar maple was the premier source of sweetener, along with honey, to Native Americans and early European settlers. Native Americans also used sugar maple sap for sugar and candies, as a beverage, fresh or fermented into beer, and soured into vinegar and used to cook meat.
Sugar maple is widely planted as an ornamental or shade tree and many cultivars have been selected, based on variation in growth habit/crown shape, mature height, fall color, leaf shape, and temperature tolerance. The leaves go from green to brilliant yellow, orange, and red in autumn, although there is much variation in fall color within the species. Orange and reds seem to be more intense in New England types, while yellows are more pronounced further west. Interior leaves may be yellow, while outer exposed leaves turn orange-red. The species is
best suited to larger sites where soil compaction is not a concern. It also is sometimes used in shelterbelt plantings and has potential value for rehabilitation of disturbed sites.
Sugar maple is an important timber tree valued for its hard, heavy, and strong wood, commonly used to make furniture, paneling, flooring, and veneer. It is also used for gunstocks, tool handles, plywood dies, cutting blocks, woodenware, novelty products, sporting goods, bowling pins, and musical instruments.
White-tailed deer, moose, and snowshoe hare commonly browse sugar maple. Red squirrel, gray squirrel, and flying squirrels feed on the seeds, buds, twigs, and leaves. Porcupines consume the bark and can girdle the upper stem. Songbirds, woodpeckers, and cavity nesters nest in sugar maple. Although the flowers appear to be wind-pollinated, the early-produced pollen may be important to the biology of bees and other pollen-dependent insects because many insects, especially bees, visit the flowers.
Acer saccharum Marsh. (sugar maple or rock maple) is a species of maple native to the hardwood forests of northeastern Canada, from Nova Scotia west through Quebec and southern Ontario to south eastern Manitoba around Lake of the Woods. In the USA, the species is common from Minnesota, to the New England states of Maine, Vermont, New Hampshire, Massachusetts, Connecticut, and Rhode Island, and down to the Eastern seaboard states of New York, New Jersey, and Pennsylvania. They are also found as far south as Georgia and Texas. Sugar maple is best known for its bright fall foliage and for being the primary source of maple syrup.
Acer saccharum is a deciduous tree normally reaching heights of 25–35 m (82–115 ft) tall, and exceptionally up to 45 m (148 ft). A 10-year-old tree is typically about 5 m (16 ft) tall. When healthy, the Sugar Maple can live for over 400 years.
The leaves are deciduous, up to 20 cm (7.9 in) long and equally wide, with five palmate lobes. The basal lobes are relatively small, while the upper lobes are larger and deeply notched. In contrast with the angular notching of the silver maple, however, the notches tend to be rounded at their interior. The fall color is often spectacular, ranging from bright yellow through orange to fluorescent red-orange, although they look best in the northern part of its range. Sugar maples also have a tendency to color unevenly in fall. In some trees, all colors above can be seen at the same time. They also share a tendency with red maples for certain parts of a mature tree to change color weeks ahead of or behind the remainder of the tree. The leaf buds are pointy and brown-colored. The recent year's growth twigs are green, and turn dark brown.
The flowers are in panicles of five to 10 together, yellow-green and without petals; flowering occurs in early spring after 30–55 growing degree days. The sugar maple will generally begin flowering when it is between 10 to 15 years old. The fruit is a double samara with two winged seeds, the seeds are globose, 7–10 mm (0.28–0.39 in) in diameter, the wing 2–3 cm (0.79–1.18 in) long. The seeds fall from the tree in autumn, where they must be exposed to 90 days of temperatures below -18 °C to break their coating down. Germination of A. saccharum is slow, not taking place until the following spring when the soil has warmed and all frost danger is past.[need quotation to verify]
It is closely related to the black maple, which is sometimes included in this species, but sometimes separated as Acer nigrum. The western American bigtooth maple (Acer grandidentatum) is also treated as a variety or subspecies of sugar maple by some botanists.
The sugar maple is also often confused with the Norway maple, though they are not closely related within the genus. The sugar maple is most easily identified by clear sap in the leaf petiole (the Norway maple has white sap), brown, sharp-tipped buds (the Norway maple has blunt, green or reddish-purple buds), and shaggy bark on older trees (the Norway maple bark has small grooves). Also, the leaf lobes of the sugar maple have a more triangular shape, in contrast to the squarish lobes of the Norway maple.
Although many people think a red sugar maple leaf is featured on the flag of Canada, the official maple leaf does not belong to any particular maple species; although it perhaps most closely resembles a sugar maple leaf of all the maple species in Canada, the leaf on the flag was specially designed to be as identifiable as possible on a flag waving in the wind without regard to whether it resembled a particular species' foliage.
The sugar maple is an extremely important species to the ecology of many forests in America and Canada. Pure stands are common, and it is a major component of the northern and central U.S. hardwood forests.
Sugar maple tends to favor cooler climates. It attains its greatest size and growth potential in southern Canada and the New England states where the growing season is 4–5 months and summers are mild. In this region, the tree is abundant and found in large stands with beech and birches, but in Zones 6-7, it gives way to oak-hickory forests and occurs only in isolated, scattered patches.
The sugar maple is among the most shade tolerant of large deciduous trees. Its shade tolerance is exceeded only by the striped maple, a smaller tree. Like other maples, its shade tolerance is manifested in its ability to germinate and persist under a closed canopy as an understory plant, and respond with rapid growth to the increased light formed by a gap in the canopy. The sugar maple can grow comfortably in any type of soil except sand.
Sugar maples engage in hydraulic lift, drawing water from lower soil layers and exuding that water into upper, drier soil layers. This not only benefits the tree itself, but also many other plants growing around it. However, like most climax forest species, sugar maple is not well-suited for landscaping due to its large size, relatively slow growth, and dense network of fibrous surface roots which can make gardening under it difficult due to their monopolization of moisture and soil nutrients.[contradiction]
Human influences have contributed to the decline of the sugar maple in many regions. Its role as a species of mature forests has led it to be replaced by more opportunistic species in areas where forests are cut over. The sugar maple also exhibits a greater susceptibility to pollution than other species of maple. Acid rain and soil acidification are some of the primary contributing factors to maple decline. Also, the increased use of salt over the last several decades on streets and roads for deicing purposes has decimated the sugar maple's role as a "street-front" tree.
In some parts of New England, particularly near urbanized areas, the sugar maple is being displaced by the Norway maple. The Norway maple is also highly shade tolerant, but is considerably more tolerant of urban conditions, resulting in the sugar maple's replacement in those area. In addition, Norway maple produces much larger crops of seeds, allowing it to out-compete native species.
Cultivation and uses
The sugar maple is one of the most important Canadian trees, being, with the black maple, the major source of sap for making maple syrup. Other maple species can be used as a sap source for maple syrup, but some have lower sugar contents and/or produce more cloudy syrup than these two. Some other trees (birch, ash, etc.) can yield a useful syrup as well, though with different flavors. In maple syrup production from Acer saccharum, the sap is extracted from the trees using tap placed into a hole drilled through the phloem, just inside the bark. The collected sap is then boiled. As the sap boils, the water is evaporated off and the syrup left behind. 40 litres of maple sap are required to be boiled to produce only 1 litre of pure syrup. This is the reason for the high cost of pure maple syrup.
The wood is one of the hardest and densest of the maples, 740 kg/m3 (46 lb/cu ft), and is prized for furniture and flooring. The sapwood can be white in color, and smaller logs may have a higher proportion of this desirable wood. Bowling alleys and bowling pins are both commonly manufactured from sugar maple. Trees with wavy woodgrain, which can occur in curly, quilted, and "birdseye maple" forms, are especially valued. Maple is also the wood used for basketball courts, including the floors used by the NBA, and it is a popular wood for baseball bats, along with white ash. It is also widely used in the manufacture of musical instruments, such as the members of the violin family (sides and back), guitars (neck), and drum shells. It is also quite flexible and makes excellent archery bows.
Canadian maple, often referred to as "Canadian hardrock maple", is prized for pool cues, especially pool cue shafts, and the highest grades of this white wood are used by virtually all (both production line and custom hand-made) cue makers to make high-quality shafts. Some production-line cues will use lower-quality Canadian maple wood with cosmetic issues, such as "sugar marks", which are (most often) light brown discolorations visible on the shaft caused by sap in the wood. Great shaft wood has a very consistent grain, and no marks or discoloration. Sugar marks usually do not affect how the cue plays, but are not as high quality as those without it. This wood is also used in skateboard decks for its strength.
The sugar maple was a favorite street and park tree during the 19th century because it was easy to propagate and transplant, is fairly fast-growing, and has beautiful fall color.[contradiction] As noted above however, it proved too delicate to continue in that role after the rise of automobile-induced pollution and was replaced by Acer platanoides and other hardier species. The shade and the shallow, fibrous roots may interfere with grass growing under the trees. Deep, well-drained loam is the best rooting medium, although sugar maples can grow well on sandy soil which has a good buildup of humus. Light (or loose) clay soils are also well known to support sugar maple growth. Poorly drained areas are unsuitable, and the species is especially short-lived on flood-prone clay flats. Its salt tolerance is low and it is very sensitive to boron.
- 'Apollo' - columnar
- 'Arrowhead' - pyramidal crown
- 'Astis' ('Steeple') - heat-tolerant, good in southeastern USA, oval crown
- 'Bonfire' - fast growing
- 'Caddo' - naturally occurring southern ecotype, great drought and heat tolerance, good choice for the Great Plains region
- 'Columnare' ('Newton Sentry') - very narrow
- 'Fall Fiesta' - tough-leaved, colorful in season, above-average hardiness
- 'Goldspire' - columnar with yellow-orange fall color
- 'Green Mountain' (PNI 0285) - durable foliage resists heat and drought, oval crown, above-average hardiness
- 'Inferno' - very hardy, with more red fall color than 'Lord Selkirk' or 'Unity'
- 'Legacy' - tough, vigorous and popular
- 'Lord Selkirk' - very hardy, more upright than other northern cultivars
- 'Monumentale' - columnar
- 'Sweet Shadow' - lacy foliage
- 'Temple's Upright' - almost as narrow as 'Columnare'
- 'Unity' - very hardy, from Manitoba, slow steady growth
Use by Native Americans
In popular culture
The sugar maple is depicted on the state quarter of Vermont, issued in 2001.
- Stevens, P. F. (2001 onwards). Angiosperm Phylogeny Website. Version 9, June 2008 [and more or less continuously updated since]. mobot.org
- The Plant List
- Germplasm Resources Information Network: Acer saccharum
- Northern Ontario Plant Database: Acer saccharum
- Oklahoma Biological Survey: Acer saccharum
- "GSMNP tall trees". Nativetreesociety.org. Retrieved 2011-03-03.
- Lawrence O. Copeland; M. B. McDonald (31 October 2001). "Principles of seed science and technology". Springer. pp. 194–. ISBN 978-0-7923-7322-3. Retrieved 25 September 2010.
- "Hydraulic lift and its influence on the water content of the rhizosphere: an example from sugar maple, Acer saccharum". Springerlink.com. Retrieved 2011-03-03.
- Heilingmann, Randall B. "Hobby Maple Syrup Production (F-36-02)". Ohio State University.
- Gibbons, E. 1962. Stalking the Wild Asparagus. David McKay.
- Hard Maple published by Niche Timbers
- Daniel L. Cassens. "Hard or sugar maple". Purdue University:Purdue Extension.
- Tantaquidgeon, Gladys 1972 Folk Medicine of the Delaware and Related Algonkian Indians. Harrisburg. Pennsylvania Historical Commission Anthropological Papers #3 (p. 69, 128)
- Horton, J. L.; Hart, S.C. (1998). "Hydraulic lift: a potentially important ecosystem process". Trends in Ecology and Evolution 13 (6): 232–235. doi:10.1016/S0169-5347(98)01328-7. PMID 21238277.
- Canham, C. D. (1989). "Different Responses to Gaps Among Shade-Tolerant Tree Species". Ecology 70 (3): 548–550. doi:10.2307/1940200.
- Brisson, J., Bergeron, Y., Bouchard, A., & Leduc, A. (1994). Beech-maple dynamics in an old-growth forest in southern Quebec, Canada. Ecoscience (Sainte-Foy) 1 (1): 40-46.
- Duchesne, L.; Ouimet, R.; Houle, D. (2002). "Basal Area Growth of Sugar Maple in Relation to Acid Deposition, Stand Health, and Soil Nutrients". Journal of Environmental Quality 31 (5): 1676–1683. doi:10.2134/jeq2002.1676. PMID 12371186.
- Melvyn Tyree. "Maple sap exudation: How it happens" (PDF). Maple Syrup Journal 4 (1): 10–11.
- Damián Cirelli, Richard Jagels, and Melvin T. Tyree (2008). "Toward an improved model of maple sap exudation: the location and role of osmotic barriers in sugar maple, butternut and white birch" (PDF). Tree Physiology (Victoria, Canada: Heron Publishing) 28 (8): 1145–1155. doi:10.1093/treephys/28.8.1145. PMID 18519246.
Names and Taxonomy
Comments: The sugar maple and the black maple are treated by Kartesz (1994, 1999) as different species (Acer saccarum and Acer nigrum, respectively); they are sometimes considered to be subspecies or varieties of the same species (in which case the name Acer saccharum has nomenclatural priority, with the black maple being called Acer saccharum ssp. nigrum or Acer saccharum var. nigrum). Note that the species Acer saccharinum (silver maple) has a similar name.
Marsh. Sugar maple is highly variable genetically and taxonomic
controversy abounds. Some taxonomists recognize two to six varieties,
but others recognize these entities as forms or subspecies [30,68].
Several ecotypes or races, each exhibiting clinal variation, have also
been delineated .
Florida maple (A. barbatum), chalk maple (A. leucoderme), and black
maple (A. nigrum) hybridize and intergrade with sugar maple and are
often included in the sugar maple complex [27,46]. Some authorities
recognize these taxa as subspecies of sugar maple , but most
delineate them as discrete species. Sugar maple hybridizes with red
maple (A. rubrum) in the field, and with bigleaf maple (A. macrophyllum)
under laboratory conditions . Acer X senecaense Slavin is a hybrid
derived from an A. leucoderme x sugar maple cross . A. skutchii is
closely related to sugar maple and is treated as a subspecies by some
The word “Acer” is derived from a Latin word meaning “sharp,” referring to the characteristic points on maple leaves. It was first applied to the genus by the French botanist Joseph Pitton de Tournefort in 1700. The species epithet, "saccharum," is from the Greek "saccharin," for sugar.
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