BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Populus grandidentata | Bigtooth Aspen 



GENERAL BOTANICAL CHARACTERISTICS : 
Bigtooth aspen is a native, short-lived, dioecious, medium-sized
deciduous tree with a straight trunk and gently ascending branches.  It
is distinguished from quaking aspen by slightly larger leaves and large
irregular teeth on the leaf edges.  The fruit is a two-valved capsule
[12,43].

Bigtooth aspen is a rapidly growing tree.  At maturity, it attains
heights of 60 to 80 feet (18-24 m) and diameters at breast height of 8
to 10 inches (20-25 cm).  Stands begin to deteriorate after 50 to 70
years on good sites, but individuals may live as long as 100 years [29].

Bigtooth aspen is a clonal species.  Clones resemble small groves
consisting of many individual stems [7].

The roots of bigtooth aspen are shallow and wide spreading; the lateral
root spread of a tree in a forest may be 33 to 66 feet (10-20 m).
Generally, four to five lateral roots originate from the tree and then
branch within 2 feet (0.6 m).  Vertical, penetrating roots near the base
anchor the tree [29].

The bark of young trees is smooth, but after three or more decades, it
becomes rough and develops grooves [7].



RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Bigtooth aspen regenerates by seed and vegetative reproduction.

Bigtooth aspen is a prolific seed producer; a single tree may produce
more than 1.5 million seeds [29].  Bigtooth aspen generally has good or
better crops (greater than 61% of a full crop) 2 out of every 3 years
[18].  The light seeds are dispersed long distances by wind [29].
Germination rates are high [14,29].  Seeds germinate under a wide range
of temperatures as long as there is sufficient moisture.  They will even
germinate when submerged in water [14].  Despite high seed production
and high germination rates, seedling establishment is uncommon.  Few
seedlings reach more than a few inches in height.  Bare moist soil free
of competition is necessary for seedling establishment.  Short seed
viability (2-3 weeks) also limits establishment.  A seedling may grow 6
to 8 inches (15-20 cm) the first year [14,29].

Most bigtooth aspen forests regenerate vegetatively.  When the parent
tree is killed or the soil is heated, suckers develop from extensive,
shallow lateral roots.  Bigtooth aspen roots that produce suckers are
generally less than 1 inch (2.5 cm) in diameter and about 3 to 7 inches
(7.5-17.8 cm) deep.  A sucker grows 3 to 6 feet (0.9-1.8 m) the first
year, considerably more than a seedling.  After a mature aspen stand is
destroyed by fire or logging, roots may produce 3,200 to 24,000 suckers
per acre (8,000-60,000/ha) [29].  Root suckers are initially dependent
on the parent roots for water and nutrients.  Their dependence decreases
with time but is still substantial after 25 years.  By age 25, the
parent roots contribute the nutrient requirements for approximately half
the yearly growth [68].

Multiple suckers result in a clone, a multistemmed vegetatively
reproduced individual.  Interclonal differences can be substantial,
especially in sprouting ability [7,36].  Within a stand, clones are
distinguished by sex, phenology, leaf morphology, disease resistance,
bark and stem differences, branching habits, and other characteristics
[7].

Sakai and Sharik [51] investigated the hypothesis that female bigtooth
aspen clones would invest energy in fruit production at the expense of
vegetative growth.  They found no significant differences (P>0.05) in
mean dbh or basal area density (basal area per unit clonal area) between
male and female clones.

The roots of bigtooth aspen may remain alive in a forest long after the
last tree has died.  The longevity of bigtooth aspen roots has not been
documented.  However, the roots of quaking aspen are known to persist in
the absence of an aspen canopy.  The roots are sustained by transient
suckers that survive only a few years [54].



SITE CHARACTERISTICS : 
Bigtooth aspen most commonly occur on floodplains, gently rolling
terrain, and the lower slopes of uplands.  Large stands grow on sands,
loamy sands, and light sandy loams.  However, minor amounts of bigtooth
aspen are found growing on almost any type of soil [29,41].  Bigtooth
aspen has a lower soil pH limit of 4.0 [63].

Bigtooth aspen tolerates drier conditions than quaking aspen [2,17,47].
It has been classified as a subxeric species [10].  However, for good
growth on upland sites the watertable must be at least 2 feet (0.6 m),
but not more than 5 feet (1.5 m), below the ground surface.  The soil
must be moist but well aerated for good growth [29].

Bigtooth aspen ranges in elevation from sea level to over 3,000 feet (915
m) in North Carolina [29].



SUCCESSIONAL STATUS : 
Facultative Seral Species

Bigtooth aspen is very shade intolerant [6,29,38]. It is a pioneer
species on disturbed sites [13]. It persists in seral communities until
senescence.  Because of the tenacity and lateral extensiveness of its
roots, aspen is able to regenerate and dominate disturbed sites that
only had a minor aspen component in the original stand [13,44].

Palik and Pregitzer [38] reported no evidence of past suppression nor
release of bigtooth aspen in a mature aspen forest.  They suggest that
most suppressed bigtooth aspen stems die.

The rapid height growth of bigtooth aspen suckers allows it to
outcompete other sprouting species such as northern red oak (Quercus
rubra) and red maple (Acer rubrum) on many sites.  Another reason for
bigtooth aspen's propensity to dominate a site after disturbance is the
large amount of space its lateral roots occupy.  Oaks (Quercus spp.) and
maples (Acer spp.) are generally limited to stump and root crown sprouts
[38].

In the absence of disturbance, bigtooth aspen is replaced by conifers
and hardwoods.  On dry sites aspen is replaced by red pine (Pinus
resinosa), oak, and red maple; on intermediate sites by eastern white
pine (Pinus strobus); and on mesic sites by northern hardwoods, spruce
(Picea spp.), and fir (Abies spp.) [13,37,56].

In the Great Lakes Region at the turn of the century, many mature pine
forests were logged and burned.  Bigtooth aspen and quaking aspen
frequently dominated the postdisturbance forests [17,27,37,50,56].
Without fire or other disturbance, these forests are being replaced by
later successional, shade-tolerant species [37,50].

In a study of forest succession in northern Michigan, bigtooth aspen,
which dominated the postfire forest, was replaced by red maple and
eastern white pine within 53 years [53].

On fine till soils in central New Hampshire, early successional species
including aspen dominate postdisturbance stands.  These species are
replaced by sugar maple (Acer saccharum) and American beech (Fagus
grandifolia) [69].

In the absence of fire, aspen-birch forests in Maine are succeeded by
spruce [70].


SEASONAL DEVELOPMENT : 
Flowering in bigtooth aspen occurs in April or May, depending on air
temperature.  The seeds mature in May or June.  Seeds disperse before
the leaves are fully expanded.  Bigtooth aspen flowers, foliates, and
disperses seeds about 1 to 3 weeks later than quaking aspen in the same
location [1,14,29].

Related categories for Species: Populus grandidentata | Bigtooth Aspen