BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Quercus nigra | Water Oak 



GENERAL BOTANICAL CHARACTERISTICS : 
Water oak is a medium-sized tree with glabrous twigs, membranous leaves,
and a straight, slender trunk.  On a good site, water oak can reach 105
feet (32 m) in height and attain 6.5 feet (2 m) in d.b.h.  It is
semievergreen in warmer parts of its range but completely deciduous in
other areas [10,43].  Water oak has a shallow, spreading rooting habit
[50].


RAUNKIAER LIFE FORM : 
   Phanerophyte


REGENERATION PROCESSES : 
Seed production and dissemination:  Water oak is monoecious.  It bears
seed by age 20, and production is good on alternate years.  The heavy
acorns are disseminated by gravity, water, and animals [50] such as blue
jays and ground squirrels, which cache acorns in the soil [8,21,44].

Germination and seedling development:  Seed viability is high.
Germination is hypogeal and occurs in the spring following maturation.
Because of a generally late spring emergence, seedling mortality from
flooding is low.  The seedlings do not tolerate prolonged submergence.
Because of the large seed, young seedlings have high initial
survivorship regardless of available light, drought stress, or
herbivory.  Seedlings require abundant moisture for the entire growing
season [45,50].

Under favorable conditions, water oak may grow 24 inches (60 cm) a
year [50].  Water oak seedlings suppressed by shade, however, grew only
1.9 inches (4.7 cm) per year in a study along the Neches River in east
Texas [45].  A suppressed individual will grow epicormic branches [50]

Vegetative reproduction:  If top-killed, water oak of all ages will
sprout fairly efficiently from the root crown [38,45,50].


SITE CHARACTERISTICS : 
Water oak grows on levees, high ridges, and elevated margins of swamps,
rivers, and hydric hammocks which flood deeply and frequently but drain
rapidly because of relief [6,12,20,37,49].  Water oak will also grow on
uplands to about 1,000 feet (300 m) in elevation where soils remain
moist [10].  Water oak grows well on better drained silty clay or loamy
soils and poorly on poorly drained clay soils.  It grows primarily on
Inceptisols [50].

Water oak is weakly to moderately tolerant of seasonal flooding.  It can
survive up to several months of flooded soil, but mortality is high if
this is a yearly occurrence.  Generally, water oak is tolerant of
several weeks of flooding each growing season [3,7].

In addition to overstory associates mentioned in SAF cover types, common
associates of water oak include Nuttall oak (Quercus nuttallii), white
oak (Q. alba), American beech (Fagus grandifolia), pecan (Carya
illinoensis), winged elm (Ulmus alata), blackgum (Nyssa sylvatica),
white ash (Fraxinus americana), yellow-poplar (Liriodendron tulipifera),
southern magnolia (Magnolia grandiflora), flowering dogwood (Cornus
florida), rough-leaf dogwood (C. drummondii), honeylocust (Gleditsia
triacanthos), Carolina laurelcherry (Prunus caroliniana), hawthorn
(Crataegus spp.), American hornbeam (Carpinus caroliniana), swamp privet
(Forestiera acuminata), spruce pine (Pinus glabra) [50].


SUCCESSIONAL STATUS : 
Facultative Seral Species

Water oak is intolerant to semi-intolerant of shade [19,34,50].  It
germinates in shade but requires moderate light for development.
Because of slow early growth, water oak does not compete well [50].

Water oak is a frequent early hardwood invader [19].  In the absence of
fire, it invades and eventually succeeds pine forests [11].  On
fine-textured loess soils that retain moisture, water oak will colonize
old abandoned fields if a seed source is nearby [40].  As a hardwood
forest matures, water oak will stabilize or decline in abundance [19].

Water oak is generally considered a subclimax or transitional species
[19,32,50].  Because of its weak to moderate tolerance of seasonal
flooding, however, water oak may form a topographic climax on ridges
elevated less than 5 feet (1.5 m) above floodplains [13,32,34].


SEASONAL DEVELOPMENT : 
Water oak staminate and pistillate flowers develop shortly before or at
the same time as new leaves.  Acorns mature in September of the second
year and are dispersed from September through November [3,50].

Related categories for Species: Quercus nigra | Water Oak