BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Quercus palustris | Pin Oak 



GENERAL BOTANICAL CHARACTERISTICS : 
Pin oak is a fast-growing, native, deciduous, monoecious tree.  It is
physiologically mature at 80 to 100 years.  Little is known of its
maximum age, but one old growth stand averaged 138 years of age.  On
good sites, pin oak may reach 120 feet (37 m) in height and 60 inches
(150 cm) in d.b.h. [19], but the tree is usually 60 to 80 feet (18-24 m)
tall at maturity [22,25].  Acorns are 0.5 inches (1.3 cm) or less in
length, the smallest of the tree oaks [11].

An open-grown pin oak has a well-defined main trunk through most of the
wide, symmetrical crown.  The upper branches are ascending, the middle
branches horizontal, and the lower branches inclined downward to give
pin oak a distinctive pyramidal shape.  Lower branches remain alive on
open-grown trees.  The branches die in closed stands, but are retained
for many years [19].  There are numerous small stiff branches on the
trunk and larger limbs [11].

Seedlings develop a strong taproot in well-aerated soils.  As trees
become older, the root system becomes more fibrous [19].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Sexual reproduction:  Seed production begins when the tree is about 20
years old, although open-grown trees may begin producing by 15 years.
Poor acorn crops occur in 3- to 4-year intervals.  Dissemination is by
animals, primarily squirrels, mice, blue jays, and woodpeckers [19].
Over a 4-week period, blue jays transported and cached 54 percent of the
available pin oak acorn crop from a stand on the campus of Virginia
Polytechnic Institute and State University in Blacksburg.  The high
percentage may be skewed, however, because of the high number of
consumers per tree on a campus compared to a forest.  The mean transport
distance between seed trees and caches was 0.7 mile (1.1 km), with a
range of 0.06 to 1.2 miles (0.1-1.9 km).  Pin oak acorns fall within the
preferred size range [0.4 to 0.7 inches (1.1-1.7 cm) in diameter] of
blue jays [6].

Pin oak acorns require a 30- to 40-day cold stratification period at 32
to 41 degrees Fahrenheit (0-5 deg C).  Viability is high.  Acorns
submerged in cold water for as long as 6 months were not damaged.  A
thick waxy coating on the pericap restricts water absorption [19].

Seedling establishment is often high after a good acorn crop year.  In a
study in southeast Missouri, there were an average of 3,500 seedlings
per acre (8,650/ha) following a high mast yield [19].  Pin oaks are most
likely to establish if the litter layer is 0.5 to 2 inches (1.3-5.1 cm)
deep.  Pin oak germination and early establishment can occur under a
dense canopy, but seedlings will die after 2 to 3 years unless they are
released.  In a study of pin oak regeneration in southern Illinois, 1-
to 2-year-old seedlings were more abundant under a closed canopy than in
an open stand where the ground cover was dense.  Seedlings over 5 years
of age, however, were more abundant in the open stands [13].
Two-year-old pin oak seedlings subjected to three shade treatments
increased their shoot/root ratio by 26 percent with increasing shade, a
reaction typical of intolerant species [18].

In a study in southern Illinois, pin oak reproduction was most abundant
in mixed hard-hardwood communities composed of oaks (Quercus spp.) and
hickories (Carya spp.); low in mixed soft-hardwood communities composed
of silver maple (Acer saccharinum), green ash (Fraxinus pennsylvania),
sweetgum, hackberry (Celtis occidentalis), and American sycamore
(Platanus occidentalis); low in eastern cottonwood (Populus
deltoides)-black willow (Salix nigra) communities; low in old fields;
and rare in newly formed land (ie. exposed sand bars) [14].

Pin oak seedlings are classified as intermediate in tolerance to shallow
flooding during the growing season [12,19].  After 60 days of completely
saturated soils, pin oak seedlings averaging 8.2 inches (20.8 cm) in
height had no shoot mortality, sparse adventitious root formation, and
some mortality of secondary roots.  Seedlings under saturated conditions
grew significantly (p<0.01) taller than the control seedlings [12].  In
another study, seedlings subjected to shallow flooding (leaves and tops
exposed) during the growing season survived 84 days, but root growth
ceased, growth was poor, and recovery was slow.  Seedlings survive only
10 to 20 days of complete inundation during the growing season.  Pin oak
seedlings suffer no adverse effect from dormant season flooding [19].

Vegetative reproduction:  Pin oak seedlings and young trees sprout
vigorously from the root collar if top-killed [19].


SITE CHARACTERISTICS : 
Pin oak occurs primarily on bottomland sites that usually flood
intermittently during the dormant season but not during the growing
season.  These sites include clay flats, depressions where water
accumulates in winter, and clay ridges of first bottoms.  Pure or nearly
pure stands of pin oak grow on level or near level moist uplands such as
the glacial till plains of southwest Ohio, southern Illinois, southern
Indiana, and northern Missouri [8,19].

It grows on acidic, poorly drained, clay to clayey loam soils (Entisols
and Alfisols) [19].

Overstory associates not mentioned in Distribution and Occurrence
include swamp white oak (Quercus bicolor), willow oak, overcup oak (Q.
lyrata), bur oak (Q. macrocarpa), Nuttall oak (Q.  nuttallii), swamp
chestnut oak (Q. michauxii), Nyssa sylvatica (blackgum), green ash,
slippery elm (Ulmus rubra), shellbark hickory (Carya laciniosa),
shagbark hickory (C. ovata), river birch (Betula nigra), Ohio buckeye
(Aesculus glabra), and American sycamore [8,19].  Shrubs and small tree
associates include American hornbeam (Carpinus caroliniana), possumhaw
(Ilex decidua), and poison-ivy (Toxidendron radicans) [8].  The
herbaceous understory associates include sedges (Carex spp.), bedstraw
(Galium spp.), and skullcap (Scutellaria spp.) [5,25].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Pin oak is intolerant of shade.  It usually occurs as a dominant or
codominant in even-aged stands.  Suppressed trees usually die within a
few years [19].  

Pin oak occurs primarily in early successional stages of bottomland
forests.  During drought or as the surface drainage in swamps and
sloughs improves, pin oak invades and replaces the first pioneer trees
such as black willow, eastern cottonwood, blackgum, swamp privet
(Forestiera acuminata), and buttonbush (Cephalanthus spp.).  With
further surface drainage, pin oak communities are succeeded by white
oak, cherrybark oak, red maple, American elm, sweetgum, and hickory
[5,8,14,25].  Pin oak communities may be edaphic climaxes on heavy wet
soils because they produce abundant regeneration which, if released,
grows faster on these sites than competing species [8,19].


SEASONAL DEVELOPMENT : 
Pin oak flowers in the spring about the same time as the leaves appear.
Acorns mature at the end of the second growing season and are dispersed
from September through early December [19].

Related categories for Species: Quercus palustris | Pin Oak