BOTANICAL AND ECOLOGICAL CHARACTERISTICS
SPECIES: Chamaecyparis thyoides | Atlantic White-Cedar 



GENERAL BOTANICAL CHARACTERISTICS : 
Atlantic white-cedar is a small to medium-sized, columnar evergreen tree
which commonly reaches 40 to 60 feet (12-18 m) in height and 36 inches
(1 m) d.b.h. [16,25,40,45].  Individuals may occasionally reach 120 feet
(37 m) in height and 60 inches (152 cm) in diameter [25].  Plants are
long-lived and can reach 1,000 years of age.  However, stands rarely
survive more than 200 years [25].

The fibrous bark is narrowly fissured by long, flat, platelike ridges
[15,37].  Scalelike leaves are opposite and average 0.06 to 0.13 inch
(1.5-3.3 mm) in length [8,36].  Atlantic white-cedar is shallow-rooted
[25].  On many swampy sites, roots are confined to the top 1 to 2 feet
(0.3-0.6 m) of peat, but on sites with lower water levels, roots may
extend considerably deeper [25].

Atlantic white-cedar is monoecious, with staminate and pistillate cones
occurring on separate shoots [25].  Small, inconspicuous yellow or
reddish staminate flowers are borne singly at the tips of short
branchlets [15,16].  Each cone contains 5 to 15 small, rounded,
laterally winged seeds [15,25].


RAUNKIAER LIFE FORM : 
   Undisturbed State:  Phanerophyte (mesophanerophyte)
   Burned or Clipped State:  Therophyte


REGENERATION PROCESSES : 
Seed:  Atlantic white-cedar reproduces solely through an abundance of
light, winged seed [14,25].  In open stands, trees first produce seed at
3 to 5 years of age and often bear large crops from 4 years of age and
up [16,45].  In dense stands, seed production may not begin until plants
reach 10 to 20 years of age [25].  As many as 9,000,000 seeds per acre
(22 million seeds/ha) may be produced annually [25].

Seed banking:  Seed can remain viable for at least 1 to 2 years when
stored in the upper inch (2.5 cm) of peat [16,19].  Little and Garrett
[25] reported the presence of 260,000 to 1,100,000 viable seeds per acre
(642,000-2,718,000/ha) within the top inch (2.5 cm) of soil.

Germination:  Germination of Atlantic white-cedar is often low due to
poor viability and embryo dormancy [16,25].  Stratification at 38 to 40
degrees F (3-4 degrees C) for 90 days may promote germination [2,25].
Delayed germination is common, and in laboratory tests up to 50 percent
of germination was delayed until the second year [16].  Results of
specific germination tests were as follows [16]:

stratification -days          germ. test              germ. capacity

 warm             cold      day     night   days          percent
  0                0        86 F    68 F     60             ----
  0               90        86 F    68 F     28               84              

Seedling establishment:  Open peat and adequate moisture are required
for good seedling establishment [25,34].  Rotting wood, sphagnum moss,
and muck or peat serve as favorable seedbeds [25].  Thick litter and
dense slash can inhibit germination and subsequent establishment [25].
Adequate light is essential for good initial growth.  Seedlings are
vulnerable to drought and flooding and often survive only on favorable
microsites [25].

Vegetative regeneration:  Heavy browsing and other types of injury can
cause plants to layer [25].  As many as 15 stems may form from the same
root system as shoots develop from lateral branches or dormant stem buds
[25,26].


SITE CHARACTERISTICS : 
Atlantic white-cedar grows in bogs or swamps bordering mesotrophic
stagnant water, in swamp forests, bayheads, along stream channels,
behind stable dunes, and in moist depressions in pine flatwoods
[5,6,8,17,47].  In New England, it is often associated with glacial
kettles and outwash plains [41].  Atlantic white-cedar grows in sun but
is also somewhat shade tolerant [9,45].  It is able to persist despite
periodic flooding [1].  Plants can grow where standing water levels
reach 1 to 2 feet (0.3-0.6 m) during parts of the year and where sites
become partially desiccated during summer [34].  Atlantic white-cedar
occurs in pure and mixed stands [36].

In addition to those species listed under DISTRIBUTION AND OCCURRENCE,
common overstory associates include eastern hemlock (Tsuga canadensis),
larch (Larix laricina), black spruce (Picea mariana), black gum (Nyssa
sylvatica), gray birch (Betula populifolia), and red maple (Acer rubrum)
in the northern portion of Atlantic white-cedar's range [19,21,32];
eastern white pine (Pinus strobus), yellow birch (Betula
alleghaniensis), and eastern hemlock (Tsuga canadensis) in some areas
[25]; and pond pine (Pinus serotina), red maple, sweetbay magnolia
(Magnolia virginiana), and white bay (Magnolia glauca) in Virginia and
North Carolina [12,19,22].  Farther south, Atlantic white-cedar grows
with loblolly bay (Gordonia lasianthus), titi (Cliftonia monophylla),
water gum, and white bay [12,19].

Understory associates:  Atlantic white-cedar stands are often
characterized by a dense, tangled, nearly impenetrable undergrowth [19].
Sweet pepperbush (Clethra alnifolia), swamp azalea (Rhododendron
viscosum), great rhododendron (Rhododendron maximum), highbush blueberry
(Vaccinium corymbosum), dangleberry (Gaylussacia frondosa), and
sweetbells leucothoe (Leucothoe racemosa) are common associates in the
northern portion of its range.  Fetterbush lyonia (Lyonia lucida),
sweetbells leucothoe, highbush blueberry, pieris (Pieris nitida),
greenbrier (Smilax laurifolia), coast pepperbush (Cletha alnifolia),
redbay (Persea borbona), palmetto (Sabal palmetto), and sweet pepperbush
grow with Atlantic white-cedar in the South [4,25,49].  Lyonia (Lyonia
spp.), mountainlaurel (Kalmia spp.), titi (Cyrilla racemiflora), and
sweet pepperbush are common associates in shrub bogs [5].

Climate:  Atlantic white-cedar grows under a warm, humid temperate to
subtropical climatic regime [5,25].  Annual precipitation averages 40 to
64 inches (102-163 cm) and temperatures range from winter lows of -36
degrees F (-38 degrees C) in Maine to 100 degrees F (38 degrees C)
during the summer in much of its range.  Growing season ranges from 140
to more than 350 days [5,25].

Soils:  Atlantic white-cedar is adapted to highly acidic soils that are
low in nutrients [41].  It typically grows on muck or peat but also
occurs on some sandy soils [25].  It is rare or absent where peat
contains significant amounts of silt or clay or where peat is underlain
by clay [25].  Atlantic white-cedar reportedly thrives on water-logged
organic soils [41].  Soils are generally acidic, with pH ranging from
3.5 to 5.5 [22].

Elevation:  Atlantic white-cedar typically grows at low elevations along
the coast.  Through most of the Northeast, it grows from sea level to
160 feet (50 m) [21] but can grow at elevations up to 1,500 feet (457 m)
in northern New Jersey [25].


SUCCESSIONAL STATUS : 
Atlantic white-cedar is long-lived but is often considered a subclimax
species [10].  Paradoxically, although some form of disturbance is
generally necessary for establishment, disturbance can lead to
conversion to hardwood types [39].  Even-aged stands of Atlantic
white-cedar often develop in response to fire, flooding, clearcutting,
or windthrow [10].  This tree is described as "intermediate in tolerance
to shade" and is unable to grow through dense shrub thickets or a
hardwood overstory [25].  In many areas, Atlantic white-cedar forests
are successional to evergreen bay forests when fire is excluded [4,5].
In the Great Dismal Swamp of Virginia and North Carolina, stands are
often replaced by red maple and black gum [30]; elsewhere in the South,
Atlantic white-cedar forests are replaced by climax stands of swamp red
bay (Tamala pubescens), white bay, and titi [34] or by sweetbay
magnolia, holly (Ilex myrtifolia), titi, and red bay (Persea pubescens)
in the absence of fire [4].

Once eliminated from a stand, Atlantic white-cedar will not regain
prominence until fire or other disturbance removes competing hardwoods
and creates a favorable seedbed.  Plants reestablish by wind-dispersed
seed when buried seed reserves have been depleted and reestablishment is
often very slow.  In some coastal areas, storm-borne saltwater can kill
hardwoods and allow Atlantic white-cedar to form nearly pure stands from
seed stored in the soil [25].


SEASONAL DEVELOPMENT : 
Pollen is generally shed in March or April [37].  Cones mature at the
end of the first growing season [16].  Most seeds are shed during
October or November, but seeds continue to be shed throughout the winter
and into the early spring [16,37].  Citing the results of a single
study, Little and Garrett [25] reported that 39 percent of all seeds had
fallen by November 15, 60 percent had fallen by December 15, and 93
percent had been shed by March 1.  Generalized flowering and fruiting
dates by geographic location are as follows:

Location        Flowering       Fruit ripe      Authority

New England     ----            July            Seymour 1985 [40]
NJ              March           Sept.-Oct.      Harris 1974 [16]
se U.S.         March-April     ----            Duncan & Duncan 1988 [9]
s NJ            April           ----            Little & Garrett 1991 [25]

Related categories for Species: Chamaecyparis thyoides | Atlantic White-Cedar