BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Acer saccharum | Sugar Maple 



GENERAL BOTANICAL CHARACTERISTICS : 
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. [36].  Sugar maple is long-lived and
plants can survive for 300 to 400 years [30].  The bark is light gray to
gray-brown and becomes deeply furrowed and rough with age [17].  Twigs
are a shiny, reddish-brown [36].  Sugar maple is relatively deep-rooted,
with many extensively-branched laterals [30,36].

Sugar maple is monoecious or dioecious [68].  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].


RAUNKIAER LIFE FORM : 
   Undisturbed State:  Phanerophyte (mesophanerophyte)
   Undisturbed State:  Phanerophyte (megaphanerophyte)
   Burned or Clipped State:  Chamaephyte
   Burned or Clipped State:  Hemicryptophyte
   Burned or Clipped State:  Cryptophyte (geophyte)


REGENERATION PROCESSES : 
Sugar maple reproduces through seed and by vegetative means.  

Seed:  Sugar maple possesses extremely effective outbreeding mechanisms
[70], and flowers are readily wind pollinated [30].  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 [30].  Large fluctuations in annual seed crops have
been reported [70].  Seed production is partly dependent on genetic
factors, and some trees produce an abundance of flowers nearly every
year [42].  In north-central Wisconsin, good or better crops are
produced at 1- to 4-year intervals [30].  Elsewhere in the United
States, good crops occur at 2- to 5-year intervals, and in Canada, at 3-
to 7-year intervals [30].  In good crop years, 264 seeds per meter
square may be produced [38].

Seed dispersal:  Seed is primarily dispersed by wind [54], which can
carry the relatively large seeds for up to 330 feet (100 m) [30].
However, most seeds do not travel more than 49 feet (15 m) from the
forest edge [38].  Some sugar maple seed may also be dispersed by water
[54].

Seed banking:  Sugar maple seed can remain viable for up to 5 years when
properly stored [30].  However, few seeds persist in the seed bank for
more than 1 year [38], and sugar maple is not considered an important
seed banker [51].

Seedling establishment:  Seedling recruitment varies annually; periodic
high seedling densities may function as a predator avoidance mechanism
[70].  In favorable years seedling recruitment may reach 18.7 seedlings
per meter square, but in poor years no seedling recruitment occurs [38].
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 [30], and mortality is often
high [70].

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 [30].  Stump-sprouting
and root-sprouting are moderately common [38].  Layering occasionally
occurs [30].


SITE CHARACTERISTICS : 
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 [32].  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 [77].

Sugar maple is a major species in seven SAF cover types and is common in
17 others [30].  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 [36].  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 tulifera) [30].

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), Solomons-seal
(Polygonatum pubescens), false Solomons-seal (Smilacina stellata), sweet
cicely (Osmorhiza spp.), adderstongue (Ophioglossom vulgatum),
jack-in-thepulpit (Arisaema atrorubens), clubmosses (Lycopodium spp.),
and largeleaf aster (Aster macrophyllus) [30].

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 [30].
Sugar maple is commonly associated with alluvial or calcareous soils
[24,32] but also grows on stabilized dunes [75].  This tree is
intolerant of flooded soils [3] and generally grows poorly on dry,
shallow soils [30].  In parts of New England, sugar maple commonly grows
on soils rich in organics [30].  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 [30].
Generalized elevational ranges by geographic location are as follows
[30]:

Location                Elevation

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)


SUCCESSIONAL STATUS : 
Sugar maple is very tolerant of shade and can persist for long periods
beneath a dense forest canopy [30].  It is noted for its ability to
quickly occupy gaps created in the forest canopy [37,64].  A bank of
abundant seedlings reamins suppressed until gaps are created by windfall
or other disturbances [37].  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 [37].  In many areas, sugar maple
is a dominant species in gaps created by dying American elms [56].

Sugar maple is generally regarded as a late seral or climax species in
many eastern deciduous forests [57].  However, as Parker and Sherwood
[58] 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 [40].


SEASONAL DEVELOPMENT : 
Growth initiation of sugar maple varies geographically [42].  Flower
buds generally begin to swell prior to the development of vegetative
buds and generally emerge 1 to 2 weeks before the leaves appear [30].
Male and female flowers mature at slightly different rates, which
promotes cross-pollination [42].  Fruit ripens approximately 12 to 16
weeks after the flowers appear [30,70].  Fruit begins to fall
approximately 2 weeks after ripening [30].  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
                                                      Association 1986  
Gulf & Atlantic   April - May       ----              Duncan & Duncan 1987    
      Coasts                                                
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 [6] and generally
drop just after seeds have fallen [30].  At the southern edge of the
species' range, dead brown leaves tend to remain on the trees through
much of the winter [28].  Trees from the northern portion of the
species' range become dormant earlier than do those from the South [42].

Related categories for Species: Acer saccharum | Sugar Maple