Lawson's Cypress

Lawson's cypress is fairly tolerant of shading, growing in both full sunlight and partial shade (2) (5). It can therefore act as both a pioneer, rapidly occupying disturbed areas in a stand, or as a climax species, gradually replacing other pioneer species in a process of succession (2). With a moderate growth rate, Lawson's cypress reaches maturity after 250 to 300 years, living for as long as 560 years, but first begins reproducing after just five to nine years (2) (5). The male and female cones begin to develop in the spring but do not become reproductively active until the following spring (2). As is the case with all conifers, pollination occurs when a small but crucial fraction of the abundant pollen produced by the male cones is transferred by wind to ovules within the female cones (8). The winged seeds reach maturity in October but are released from the cones throughout the year and are dispersed by both wind and water (2).

The priority for Lawson's cypress conservation is to control the spread of the root rot. As the fungal spores require moist conditions to survive, existing control methods are focused around restricting human and vehicle movements through Lawson's cypress habitat during the wet season (2) (10). There is also a program to cultivate trees that are resistant to the disease, but it will take hundreds of years before resistant seedlings will grow large enough to replace old-growth stands. Consequently the fate of surviving stands is for now completely dependent on the effective control of the spread of the disease (10).

While a popular and widespread garden conifer, natural populations of Lawson's cypress are restricted to a small range and have declined significantly over the past 150 years (3) (4). Lawson's cypress is a tall, conical tree with short branches and flattened twigs, bearing blue-green, scale-like leaves that form a dense crown (3) (5). The thick, furrowed bark of mature trees, which enables this species to survive moderate fires, is red-brown to silver-brown (2) (5) (6). Male and female cones are borne on the same branches but are very different in appearance; male cones are small, red-brown and oblong, whilst female cones are relatively large and spherical, and begin green but turn red-brown at maturity (5) (6). Under cultivation this species mutates very easily and consequently occurs in a remarkable variety of forms, often barely resembling the appearance of naturally occurring individuals (4) (7).

Lawson's cypress occurs naturally where soil water is abundant during the summer, as is the case with the moisture-laden climes of its native range (2) (3). It grows on a wide variety of soil types and often with several other conifer species (2) (5).

The native range of Lawson's cypress is limited to coastal northern California and southern Oregon (2).

Classified as Vulnerable (VU) on the IUCN Red List (1).

Historically, Lawson's cypress has been heavily exploited and international trade for its commercially valuable wood continues to put enormous pressure on the remaining old-growth stands (2) (9). Nonetheless, it is the spread of a root rot, Phytopthora lateralis, that presents the biggest threat to the future of the species. Originating from an unknown source in the mid-20th century, this root rot, which only affects Lawson's cypress, has spread throughout most of its native range (2) (5). It spreads via aquatic spores in mud and water and can be transported by people, animals and machinery (2). Numerous stands have been eliminated by this lethal disease and it is preventing successful regeneration in many areas (2) (9). As of yet, very few naturally resistant trees have been identified and there are no effective chemical controls (2) (5) (10).

In Great Britain and/or Ireland:
Foodplant / mycorrhiza / ectomycorrhiza
fruitbody of Amanita inopinata is ectomycorrhizal with live root of Chamaecyparis lawsoniana
Remarks: Other: uncertain
Other: major host/prey

Foodplant / sap sucker
Cinara cupressi sucks sap of live foliage of Chamaecyparis lawsoniana
Remarks: season: 5-8

Plant / associate
fruitbody of Geastrum pectinatum is associated with Chamaecyparis lawsoniana

Foodplant / saprobe
fruitbody of Hemimycena lactea is saprobic on dead debris of Chamaecyparis lawsoniana

Foodplant / saprobe
fruitbody of Leucoagaricus marriagei is saprobic on dead, decayed leaf of litter of Chamaecyparis lawsoniana
Other: minor host/prey

Foodplant / saprobe
fruitbody of Marasmiellus ramealis is saprobic on dead, fallen, decayed brash of Chamaecyparis lawsoniana
Other: major host/prey

Foodplant / pathogen
Phytophthora cinnamomi infects and damages necrotic root of Chamaecyparis lawsoniana
Other: major host/prey

Foodplant / pathogen
Phytophthora lateralis infects and damages brown needle of Chamaecyparis lawsoniana

Foodplant / saprobe
dominant Ptychogaster anamorph of Postia ptychogaster is saprobic on dead, decayed stump of Chamaecyparis lawsoniana
Other: major host/prey

Foodplant / feeds on
Trisetacus chamaecypari feeds on foliage of Chamaecyparis lawsoniana

Port-Orford-cedar
Port Orford-cedar
Port-Orford white-cedar
Lawson cypress
Lawson false-cypress
false cypress
Oregon-cedar
white cedar
ginger pine

More info for the terms: forest, tree

Port-Orford-cedar is a long-lived, shade-tolerant, coniferous, evergreen
tree. Mature trees typically grow up to 200 feet (60 m) tall and have 4
to 6 foot (122-183 cm) diameter trunks [7]. The largest tree on record
is 239 feet (73 m) tall with a 12 foot (3.6 m) diameter trunk [11].
Trees can live more than 600 years. Old trees have an enlarged base, a
50 to 70 foot (15.2-21.3 m) long branch-free bole, and a spirelike head
of small horizontal or pendulous branches with slender flattened
branchlets [24,35]. Occasionally the trunk will fork. The leaves are
small, scalelike, and arranged close to the branchlets.
Port-Orford-cedar has no taproot but produces vertical sinkers from the
wide-spreading horizontal root system [37]. This makes trees subject to
windthrow. The bark of mature trees is very thick, up to about 10
inches (25 cm) [37].

Growth and height of mature trees varies considerably among different
forest communities. Height-to-age relationships of Port-Orford-cedar
trees in different forest communities throughout its range is summarized
below [12]:

Community Height of Port-Orford-cedar at different ages (years)
100 200 300
meters feet meters feet meters feet

western hemlock/swordfern
(TSUHET-CHALAW/POLMUN-OXAORE) 30 98 47 154 63 207

western hemlock/rhododendron
(TSUHET-CHALAW/RHOMAC-GAUSHA) -- -- 45 148 53 174

mixed fir
(Abies spp.-CHALAW/herb) 12 39 36 118 50 164

white fir
(ABICON-CHALAW/herb) 13 43 25 82 46 151

tanoak
(CHALAW/LITDEN) 12 39 29 95 44 144

white fir-hemlock
(ABICON-TSUHET-CHALAW) 12 39 26 85 41 134

western hemlock/beargrass
(CHALAW-TSUHET/XERTEN) 13 43 25 82 31 102

mixed pine
(Pinus spp.-CHALAW/QUEVAC/ 18 59 21 69 29 95
XERTEN)

Port-Orford-cedar readily grows under the shade of other conifers but
grows faster in the open [13]. Generally it grows slower than
Douglas-fir (Pseudotsuga menziesii). Recent research suggests that
Port-Orford-cedar is one of the most shade-tolerant conifers throughout
its range [12,36]. Seedlings and saplings are often found in the shade
of old-growth forests.

Port-Orford-cedar has a very limited distribution, occurring near the
Pacific Ocean in southwestern Oregon and northwestern California. The
northern limit of its distribution is near Coos Bay, Oregon. The
species' range extends southward about 220 miles (350 km) to the central
portion of the Mad River drainage in Humboldt County, California [10].
Isolated populations occur near Mount Shasta and the Trinity Mountains
in northern California [7,10]. It occurs in greatest abundance within
about 40 miles of the coast [7]. Farther inland, its distribution is
spotty, and it is mostly limited to sites with abundant soil moisture
and/or atmospheric moisture [3,37]. Port-Orford-cedar is cultivated in
Hawaii [39].

More info for the terms: fire frequency, fire regime, forest, frequency, fuel, litter, seed, tree

Although young Port-Orford-cedar trees are easily killed by fire,
relatively old trees are very fire resistant because their bark may be
up to 10 inches (25 cm) thick. It is apparently less fire resistant
than Douglas-fir, Ponderosa pine, sugar pine, Jeffrey pine, and
incense-cedar, but more fire resistant than true firs and hemlocks
[27,37]. Many vigorous old trees show evidence of repeated burning and
have large fire scars [8,37]. A stump in Oregon that was 21 inches (54
cm) in diameter and 285 years old had fire scars at 35, 183, and 228
years [37]. Some fires have removed all but a thin, incomplete outer
shell of wood and bark at the tree base, yet trees remain healthy [37].
These surviving trees provide a seed source for postfire seedling
establishment. Pole-sized trees have moderate fire resistance and can
probably withstand ground fires [37].

Port-Orford-cedar drops much less litter on the forest floor than
Douglas-fir [1]. Fire frequency is partially dependent upon this fuel
accumulation. Atzet [1] rated the likelihood of fire occurring under
different conifer stands as follows:

Less Likely
-----------
red fir
Jeffery pine
Port-Orford-cedar
tanoak
Douglas-fir
white fir
-----------
More Likely

On inland sites Port-Orford-cedar mostly occurs along stream channels,
boggy drainages, other moist topographic concavities or north aspects
[3]. These sites have a low probability of fire carrying after ignition
[2].

FIRE REGIMES :
Find fire regime information for the plant communities in which this
species may occur by entering the species name in the FEIS home page under
"Find FIRE REGIMES".

More info on this topic.

More info for the term: phanerophyte

Phanerophyte

More info for the terms: bog, competition, forest, hardwood, litter, mesic, shrub, shrubs, tree, ultramafic soils

Although restricted to a small range that covers only 220 miles (350 km)
from north to south, Port-Orford-cedar occupies many vegetation zones,
soil types, and elevations. It commonly grows in mixed stands but
occasionally forms pure stands. It occurs mainly within Sitka spruce,
western hemlock, white fir, redwood (Sequoia sempervirens), red fir
(Abies magnifica), mixed-pine, and mixed-evergreen forests
[3,8,10,12,27,28,31]. Within each forest, Port-Orford-cedar is
primarily restricted to moist locations such as benches, drainageways,
or some type of concavity which receives a constant seepage of water
[3,12,36,37]. It is mostly absent from ridges and upper slopes due to
the lack of water; however, some coastal Oregon and upper elevation
Klamath Mountain stands do occupy top-slope positions [12,36,37].
Port-Orford-cedar also occurs on coastal dunes and in bogs with
ultramafic soils.

Common associates: Besides the above mentioned species,
Port-Orford-cedar is commonly associated with Douglas-fir, grand fir
(Abies grandis), lodgepole pine (Pinus contorta), western redcedar
(Thuja plicata), and Pacific yew (Taxus brevifolia) in coastal areas
[12,13]. Inland tree associates include sugar pine (P. lambertiana),
western white pine (P. monticola), incense-cedar (Calocedrus decurrens),
and Pacific yew [3,12,13]. Hardwood tree associates include tanoak
(Lithocarpus densiflorus), Pacific madrone (Arbutus menziesii), golden
chinkapin (Chrysolepis chrysophylla), red alder (Alnus rubra), and
canyon live oak (Quercus chrysolepis) [3,12,13]. Associated shrubs
include dwarf Oregongrape (Berberis nervosa), salal (Gaultheria
shallon), oceanspray (Holodiscus discolor), the shrub form of tanoak (L.
densiflorus var. echinoides), Sadler oak (Q. sadleriana), huckleberry
oak (Q. vaccinifolia), Pacific rhododendron (Rhododendron macrophyllum),
western azalea (Rhododendron occidentale), baldhip rose (Rosa
gymnocarpa), red huckleberry (Vaccinium parvifolium), and evergreen
huckleberry (V. ovatum) [3,12,13].

Soils: Port-Orford-cedar occurs on many different soil types including
dune sands, organic bog soils, and soils derived from gabbro, diorite,
serpentine, peridotite, river alluvium, and other rock types [30,37].
On diorite it is more commonly found above 2,500 feet (760 m) [30].
Most low elevation Port-Orford-cedar forests occur on soils derived
from ultramafic parent materials [37]. Port-Orford-cedar is more
successful in communities where the parent material is at least
partially derived from ultramafic rock and where competition is somewhat
reduced [77]. On all soil types, Port-Orford-cedar is limited to mesic
situations [37].

Litter: The litter layer under eight Port-Orford-cedar communities was
found to be relatively shallow, averaging only 0.4 to 1.6 inches (1-4
cm) deep [12]. The foliage of Port-Orford-cedar is less acidic than
Pinaceae. Thus the litter and soil under Port-Orford-cedar stands are
less acidic than under nearby conifer stands [37].

Climate: Port-Orford-cedar is distributed over an area that has warm,
dry summers and cool, wet winters. Most stands in California receive at
least 59 inches (150 cm) of precipitation annually [37]. Inland
disjunct stands receive at least 49 inches (125 cm) of precipitation
annually.

Elevation: Port-Orford-cedar is found from sea level to 5,100 feet
(1,554 m) in elevation [3].

More info on this topic.

This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):

207 Red fir
211 White fir
223 Sitka spruce
229 Pacific Douglas-fir
231 Port Orford-cedar
232 Redwood
233 Oregon white oak
234 Douglas-fir - tanoak - Pacific madrone
243 Sierra Nevada mixed conifer
247 Jeffrey pine

More info on this topic.

This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):

FRES20 Douglas-fir
FRES21 Ponderosa pine
FRES23 Fir - spruce
FRES24 Hemlock - Sitka spruce
FRES27 Redwood
FRES28 Western hardwoods

More info on this topic.

This species is known to occur in association with the following plant community types (as classified by Küchler 1964):

More info for the term: forest

K001 Spruce - cedar - hemlock forest
K002 Cedar - hemlock - Douglas-fir forest
K005 Mixed conifer forest
K006 Redwood forest
K007 Red fir forest
K026 Oregon oakwoods
K028 Mosaic of K002 and K026
K029 California mixed evergreen forest

More info for the term: forest

Relatively small Port-Orford-cedar trees are easily killed by fire.
Repeated fires can eliminate all the Port-Orford-cedar regeneration size
classes from mature forest understories [1]. This is probably why
Port-Orford-cedar is rare where fires occur frequently [2].

More info for the term: seed

As a food source, Port-Orford-cedar is of little importance to wildlife
and livestock. Seedlings and saplings within regenerating stands show
little browsing damage [37]. Some plantations, however, have shown
moderate use. In a wildlife damage study, 19 percent of
Port-Orford-cedar in 8- to 26-year-old plantations was moderately or
severely damaged from browsing. Sixty percent of the damage was from
deer and elk, and 40 percent from domestic livestock and small mammals
[13].

Douglas squirrels harvest Port-Orford-cedar cones and eat the seed [32].
Mountain beavers and rabbits occasionally eat the foliage of saplings,
and woodrats and porcupines eat the bark [23,37]. Caged white-footed
deer mice showed a dislike for Port-Orford-cedar seed [23].

More info for the term: climax

Port-Orford-cedar is found in many vegetation types where it either
forms small, pure stands, codominates with other conifers, or occurs as
scattered trees. It is a long-lived, shade-tolerant climax species that
dominates or codominates with other coniferous trees to form mature
stands within four vegetation zones. The following published
classification schemes list Port-Orford-cedar as a climax species or
dominant part of the vegetation in community types (cts) or plant
associations (pas) within the Sitka spruce (Picea sitchensis), white fir
(Abies concolor), western hemlock (Tsuga heterophylla), and
mixed-evergreen zones:

Area Classification Authority

CA, OR: Siskiyou Mtns general veg. pas Atzet & Wheeler 1984

OR: Upper Illinois general veg. cts Atzet 1979
River drainage

CA, OR Port-Orford-cedar cts Hawk 1977

OR, WA general veg. cts Franklin & Dyrness 1973

More info for the term: tree

Tree

More info for the terms: forest, natural, root crown

Port-Orford-cedar is extremely susceptible to a fatal root rot caused by
two soil-borne fungi, Phytophthora lateralis and P. cinnamomi. The
crown of infected trees changes color from the normal blue-green to
gold, bronze, reddish brown, and finally a dull brown. Moisture stress
in the spring and summer initiates the rapid death of the entire crown.
Within the roots, the fungus moves from the root tips throughout the
tissue to the root crown. Roots turn a dark brown and finally black and
rot within a few months [35].

Sometime prior to 1923, root rot spread within hundreds of nurseries,
ornamentals, and windbreaks in the Pacific Northwest north of the
natural range of Port-Orford-cedar and attacked only Port-Orford-cedar
[35,37]. In 1952 the disease was introduced into the natural range of
Port-Orford-cedar, apparently from infected soil of transplanted
ornamentals [35]. The disease has now spread throughout much of the
range of Port-Orford-cedar. The fungus is carried through water-borne
spores transported primarily by natural water flow or in mud carried by
animals or machinery. Thus spread of the disease has been greatly
accelerated by road construction and maintenance, logging, and house
building [35,37]. In the 1970's mortality of old-growth trees was about
10 million board feet annually and has gradually decreased to about 5
million board feet annually, largely due to the depletion of the
resource [37]. About 60 percent of coastal second-growth
Port-Orford-cedar which developed following cutting from 1880 to 1930
has been lost to this disease [37]. It may be over 100 years before
Port-Orford-cedar harvest can contribute significantly to the regional
economy, and this will only happen through proper timber and disease
management [37].

There is currently no known cure for trees infected with root rot. Work
is being conducted to find a genetic source resistant to root rot for
developing planting stock [35]. Root rot can be avoided on sites where
topography prevents the flow of runoff water [35]. For future harvests,
managers may have to concentrate on growing Port-Orford-cedar on sites
unlikely to be reached by the fungus [37]. Current root rot management
generally consists of minimizing the spread of the disease by
restricting or regulating human activities. Zobel and others [37]
discuss ways to manage Port-Orford-cedar to minimize the spread of the
root rot disease. With a better understanding of root rot, planting has
begun on some federal and forest industry lands. Eight to 12 inch
(20-30 cm) tall container stock has been planted at 20 to 26 foot (6-8
m) spacing [37]. The wide spacing minimizes root overlap and root to
root spread of the root rot fungus.

Because of its high commercial value, numerous Port-Orford-cedar
plantations were begun north of its natural range prior to 1950. In the
fall of 1955, a severe cold spell caused high mortality of trees on
these plantations [14]. Some plantations received up to 100 percent
mortality. Because of its susceptibility to cold injury and root rot,
Port-Orford-cedar should not be used in forestry projects outside its
natural range [14].

CA HI OR

More info for the terms: natural, tree

Port-Orford-cedar is a commercially important ornamental tree in Europe.
Numerous cultivars exist. It was first cultivated in 1854. Within the
natural range of Port-Orford-cedar, branches are collected for use in
florist's greens [37]. This activity is often regulated by permits.
Native Americans used Port-Orford-cedar wood for house planks, canoes,
utensils, and arrows, and wove the shredded bark into clothing [37].

Port-Orford-cedar appears to be of low palatability to hooved browsers.

More info on this topic.

More info for the terms: phenology, seed

Shoot growth of Port-Orford-cedar differs greatly from that of pines and
firs. Pines and fir species have bud tissue which preforms the
following year's shoots. Port-Orford-cedar does not have preformed
buds; therefore shoot elongation over the summer takes longer than
competing Pinaceae. Port-Orford-cedar grows much slower than
Douglas-fir, and in the northern part of its range where
Port-Orford-cedar grows best, prolonged shoot elongation may be
necessary for it to compete. Port-Orford-cedar's twig growth phenology
may partially explain its northern distributional limit. North of its
range, the prolonged shoot elongation needed to make plants more
competitive with other conifers would make them susceptible to frost.
Port-Orford-cedar grows on hot open sites and tends to initiate twig
growth earlier and often completes growth more quickly than trees on
colder sites. (the above information is summarized from Zobel 1983 [34])

Port-Orford-cedar flower buds are typically set in the fall with
pollination taking place the following spring [13]. Cones ripen in
September or October with seed dispersal occurring immediately
thereafter and continuing until spring [11,32].

More info for the terms: fire-free interval, seed

Mature Port-Orford-cedars are very fire resistant and often survive
fire. Seed dispersed from surviving trees allows Port-Orford-cedar to
rapidly establish numerous seedlings. Seedlings may maintain dominance
for a few years but are usually overgrown by faster growing conifers
within about 20 to 25 years [13]. Since Port-Orford-cedar is very shade
tolerant, trees established following a fire will persist in the
understory and eventually replace other conifers such as Douglas-fir if
there is a sufficient fire-free interval to allow trees to grow to a
fire-resistant size [1,13]. Some sampled stands have two or more
distinct size classes, each thought to have become established following
a fire [12,37].

More info for the term: seed

crown-stored residual colonizer; short-viability seed in on-site cones
off-site colonizer; seed carried by wind; postfire years 1 and 2

More info for the terms: basal area, cone, forest, layering, litter, natural, seed, seed tree, tree

Sexual regeneration: The primary method of natural reproduction of
Port-Orford-cedar is via seed. Trees produce seed in sufficient
abundance to ensure seedling establishment under forest stands.
Currently, where root rot is not a problem, Port-Orford-cedar is
reproducing itself in almost all Port-Orford-cedar communities [12].

Male and female flowers are found on the same branch but on different
branchlets. Flower buds begin growth in the spring and become fully
developed by the end of the summer. Pollination occurs the following
spring, and seeds become fully developed by September or October [13].
The seeds are borne in small cones that are from 0.25 to 0.5 inch
(0.6-1.2 cm) in diameter [11].

Port-Orford-cedar seeds have small, thin marginal wings, weigh about 2
mg each, and are about 0.11 to 0.16 inch (3-4 mm) long [37]. Harris
[11] reports that seeds are quite variable in weight and size, requiring
from 60,000 to 600,000 to equal a pound.

Port-Orford-cedar begins to produce seed early, between 5 and 9 years of
age. Cone production becomes greatest at about age 100 and continues
throughout the life of the tree [13]. Although trees produce seed every
year, heavy seed crops are produced every 4 or 5 years [13,32]. Zobel
[32] found annual seed production to vary considerably from year to year
and from site to site within a given year, from 8,097 to 1,862,348 seeds
per acre (20,000-4,600,000/ hectare) and from 56 to 17,193 seeds per
square foot of tree basal area (600 to 185,000/sq m). The variability
was not clearly related to stand or site factors. Seed fall begins in
September and continues throughout winter and spring. Generally about
50 to 60 percent of the seed has fallen by mid-January, with 90 percent
or more fallen by the beginning of May [13,32]. Dispersal distance is
generally short. One to three tree heights is a common distance of
invasion into clearcuts [37]. The small wings aid in floating on water.
Dispersal by water may be of some importance in streamside habitats.

Most Port-Orford-cedar seed germinates the first spring after dispersal,
but a very small amount may lay dormant for up to 5 years [13].
Germination generally occurs from mid to late June [33]. Viability of
seed can be low. Germination of seed collected from seed traps from
many sites ranged from 13.8 to 44.2 percent [32]. In this study, seeds
which fell early or late had lower germination percentages than seeds
which fell during peak seed fall, and seed collected from trees had
higher germination percentages (37, 52, and 55 percent) than seed
collected from seed traps [32]. This is much closer to the 48 to 52
percent range reported by Harris [11]. Seed may be stored in sealed
containers at temperatures below freezing with seed moisture content
below 10 percent. Viability of seed stored in this manner for 7 years
dropped from an initial 56 to 43 percent [11].

Seedling establishment on forest floor litter accounts for the majority
of natural Port-Orford-cedar reproduction. The litter layer under
Port-Orford-cedar is generally shallow, averaging about 0.4 to 1.6
inches (1-4 cm) [12]. First year survival of seedlings is often about
50 percent [13,33] but drops dramatically thereafter. Disturbance of
the mineral soil can greatly enhance establishment. Native
Port-Orford-cedar seed was sown on plots that were treated as follows:
(1) undisturbed with the litter left intact, (2) the litter removed, (3)
burned, or (4) spaded after litter was removed. The most germinants and
the most surviving germinants after one growing season were found on
spaded plots [33]. By the end of two growing seasons, no seedlings
survived on plots that were burned or had the litter removed. After
three seasons, 5 percent of the original germinants survived on spaded
plots and 6 percent survived on undisturbed plots. Seedlings and
saplings are often found growing in the open or under shade but not
under extremely dense shade. One study found that live seedlings were
found growing in 0.7 to 2.5 percent of full light, but that dead or
nearly dead seedlings were on sites receiving only 0.2 to 0.4 percent of
full light [36]. Thus seeds may germinate in dense, young stands, but
extreme shading can cause total mortality of emerging seedlings.
Following clearcutting or shelterwood cutting, Port-Orford-cedar
successfully establishes from seed within about 88 to 132 yards
(80-110 m) from a seed tree [18]. Emerging seedlings are delicate and
probably sensitive to drought [13]. Within a deer exclosure 1-year-old
seedlings averaged 1.4 inches (3.6 cm) in height, and 2-year-old
seedlings averaged 3.1 inches (7.9 cm) [11].

Vegetative regeneration: Vegetative regeneration is very limited in
Port-Orford-cedar. Plants do not naturally sprout. However, stem
cuttings root relatively easily if proper methods are followed [5,37].
Layering occurs infrequently and is restricted mostly to trees buried by
sand or thrown by wind [37].

More info on this topic.

This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):

1 Northern Pacific Border
4 Sierra Mountains

More info on this topic.

More info for the terms: climax, seed

Port-Orford-cedar occurs as both an early seral invader and as a
long-lived, shade-tolerant climax species. Seedlings become established
after disturbances such as clearcutting or fire but also become
established within mature forests. Continual seedling establishment and
shade tolerance produce stands with many age classes [12].

Following disturbances such as fire or cutting, Port-Orford-cedar
readily establishes where a seed source exists. Fire can eliminate
young trees, but old-growth trees are very fire-resistant and often
survive fire to reseed the site. In some old forests, two or more size
classes of Port-Orford-cedar may exist, resulting from the establishment
of trees following periodic fires [12].

More info for the term: natural

The currently accepted scientific name of Port-Orford-cedar is
Chamaecyparis lawsoniana (A. Murr.) Parl. [19,21,24]. There are no
recognized subspecies, varieties, or forms; however, over 200 cultivars
have been developed which vary in size, shape, branching, and coloration
[37].

Port-Orford-cedar belongs to the family Cupressaceae. The genus
Chamaecyparis includes eight taxa of which Port-Orford-cedar is the
largest in size. The range of Alaska-cedar (Chamaecyparis nootkatensis)
overlaps that of Port-Orford-cedar, but natural hybrids are extremely
rare [37].

Due to its susceptibility to a fatal root rot, Port-Orford-cedar is
probably of very limited use for rehabilitating disturbed sites (see
Management Considerations).

Since its discovery by European settlers in the 1850's,
Port-Orford-cedar wood has been used in manufacturing many diverse
products. Early use was primarily as lumber for house and ship
building, timbers for mines, and in the manufacture of furniture.
Port-Orford-cedar has been used in making a variety of products
including airplanes, arrow shafts, boats, cabinets, crates, decking,
doors, handles, hangers, lawn furniture, mouldings, plywood, telephone
poles, screens, shelves, siding, stools, tables, toys, and yardsticks.
During the 1920's and 1930's production increased dramatically because
of two specialty industries: the manufacture of battery separators and
venetian blinds. Following World War II, substitute materials were
found for these products. Subsequently domestic use almost disappeared,
and today remains almost nonexistent.

Today nearly all harvested Port-Orford-cedar is exported to Japan.
Port-Orford-cedar is very similar to hinoki (Chamaecyparis obtusa) wood,
which is used in traditional Japanese house and temple construction. On
federal timber sales, Japanese trading companies sometimes purchase
stumpage on bid after examining individual trees. The wood is regarded
so highly as a hinoki substitute that trees are felled with great care;
sometimes cables are used to control the fall. Because the supply of
hinoki is very limited, Port-Orford-cedar sells for a premium price as a
hinoki substitute. Logs exported from the Powers Ranger District,
Oregon, in 1981 sold for an average of $2,166 per thousand board feet.
(the above information is summarized from Zobel and others 1985 [37] and
Zobel 1986 [35])

Port-Orford-cedar is found with an extremely wide variety of associated plants and vegetation types. It usually grows in mixed stands and is important in the Picea sitchensis, Tsuga heterophylla, mixed evergreen, and Abies concolor vegetation zones of Oregon (3,13) and their counterparts in California (1). It also grows in a variety of minor communities from dry sand dunes to Darlingtonia (cobra-lily) bogs. The species reaches its greatest size and commercial worth in the dense, rapidly growing forests of the Picea sitchensis and the Tsuga heterophylla zones, in which Douglas-fir often dominates. Port-Orford-cedar is most dominant on wet soils, most of which have parent material at least partially ultramafic, in the high elevation Abies concolor zone where forests are dense but slow growing (13). In the mixed evergreen zone, it is the only shade-tolerant conifer in most stands. On drier sites on ultramafics and in bogs, forests can be very open and slow growing. The cedar is dominant in the forest cover type Port-Orford-Cedar (Society of American Foresters Type 231) (2) and is listed as a minor associate for parts of the following types: Sitka Spruce (Type 223), Pacific Douglas-Fir (Type 229), Redwood (Type 232), Oregon White Oak (Type 233), and Douglas-Fir-Tanoak-Pacific Madrone (Type 234).

Major communities in old-growth forests where Port-Orford-cedar is a major component include the following, named for the apparent dominants at climax (abbreviated names are given in parentheses) (13):

Tsuga heterophylla zone-
Tsuga heterophylla-Chamaecyparis lawsoniana/Polystichum munitum-Oxalis oregana (swordfern); Tsuga heterophylla-Chamaecyparis lawsoniana /Rhododendron macrophyllum-Gaultheria shallon (rhododendron); Chamaecyparis lawsoniana-Tsuga heterophylla/Xerophyllum tenax (bear grass).

Mixed evergreen zone-
Chamaecyparis lawsoniana/Lithocarpus densiflorus (tanoak); Pinus-Chamaecyparis lawsoniana/Quercus vaccinifolia/Xerophyllum tenax (mixed pine).

Abies concolor zone-
Abies concolor-Tsuga heterophylla-Chamaecyparis lawsoniana (white fir-western hemlock); Abies concolor-Chamaecyparis lawsoniana/herb (white fir); Abies-Chamaecyparis lawsoniana/herb (mixed fir).

Port-Orford-cedar is less common in a wider variety of forest communities.

Plants of major importance associated with Port-Orford-cedar vary among zones (6,13). Trees are Sitka spruce (Picea sitchensis), western hemlock (Tsuga heterophylla), Douglas-fir (Pseudotsuga menziesii), tanoak (Lithocarpus densiflorus), sugar pine (Pinus lambertiana), Jeffrey pine (P. jeffreyi), western white pine (P. monticola), redwood (Sequoia sempervirens), white fir (Abies concolor), and Shasta fir (A. magnifica var. shastensis).

Shrubs are Pacific rhododendron (Rhododendron macrophyllum), western azalea (R. occidentale), evergreen huckleberry (Vaccinium ovatum), red huckleberry (V. parvifolium), salmonberry (Rubus spectabilis), cascara buckthorn (Rhamnus purshiana), California buckthorn (R. californica), salal (Gaultheria shallon), Pacific bayberry (Myrica californica), huckleberry oak Quercus vaccinifolia), Sadler oak (Q. sadleriana), western leucothoe (Leucothoe davisiae), Pacific yew (Taxus brevifolia), Oregongrape (Berberis nervosa), and Oregon boxwood (Pachistima myrsinites).

Important herbs are swordfern (Polystichum munitum), Oregon oxalis (Oxalis oregana), beargrass (Xerophyllum tenax), western twinflower (Linnaea borealis var. longiflora), vanillaleaf (Achlys triphylla), prince's-pine (Chimaphila umbellata var. occidentalis), Hooker fairybells (Disporum hookeri), western starflower (Trientalis latifolia), and inside-out-flower (Vancouveria spp.).

The general relationships of well-developed Port-Orford-cedar forests to rock type, geographic location, and elevation are shown in figure 1. These forests have 75- to 86-percent cover by trees more than 15 cm (6 in) in d.b.h., except the mixed pine community, which has 39 percent. Tree reproduction is often abundant, and density of trees less than 15 cm (6 in) in d.b.h. ranges from 1246/ha (rhododendron community) to 4113/ha (white fir) (504 to 1,664/acre); 26 percent (swordfern) to 78 percent (tanoak) of these are Port-Orford-cedar; cover of tree reproduction ranges from 30 to 46 percent.


Figure 1-Distribution of vegetation zones and eight major
forest communities of old-growth Port-Orford-cedar, in
relation to soil parent material, elevation, and geographic
location. Zones are separated by solid lines, communities by
broken lines (modified from 6).

Shrub cover is very dense in rhododendron and tanoak communities (over 90 percent), moderate to dense in most communities (30 to 67 percent), but only 9 percent in the swordfern community. Moss cover is high in the Tsuga zone.

Representation of Port- Orford-cedar is usually lower in the forest than in the cedar-dominated communities described above (13). For example, on 3752 ha (9,271 acres) of the former Port Orford Cedar Experimental Forest in southern Coos County, OR, 28 percent of total timber volume was Port-Orford-cedar. Cedar volume exceeded 50 percent on 41 percent of the area, was 25 to 50 percent on 7 percent of the area, 10 to 24 percent on 15 percent of the area, and less than 10 percent on the remainder.

The Pacific Ocean strongly influences the climate of most of the range of Port-Orford-cedar. Winters are cool and wet; summers are warm and dry (13). Precipitation is moderate to high, usually 1000 to 2250 mm (39 to 89 in); only 2 to 4 percent occurs from June to August. A snowpack of 1 to 2 m (3 to 7 ft) is common at the higher elevations of the Klamath Mountains. Humidity remains high at night in most areas, although some interior valley sites have dry air during the day. Fog is common along the immediate coast and during the morning in some smaller interior valleys; summer cloudiness is most common near the northern end of the range. Temperatures varied widely in 2 years of measurement (13). At three coastal sites, monthly average understory air temperatures at 1 m (3 ft) ranged from 5° C (41° F) in January to 14° C (57° F) in July; the mean annual temperature was 8.5° C (47° F). At the warmest site at 360 m (1,180 ft) near Kerby, OR, monthly averages were 3° to 22° C (37° to 72° F) and annual average was 11.3° C (52° F); at the coldest site, southwest of Mount Shasta, CA, at 1520 m (4,980 ft), monthly averages were -2° to 14° C (29° to 57° F) and annual average was 5.2° C (41° F). The lowest air temperature measured in a Port-Orford-cedar stand was -15° C (5° F) at a height of 1 m (3 ft). Soil temperatures at 20 cm (8 in) below the surface were generally cool; the annual mean was 4° to 11° C (39° to 52° F). The average difference between the warmest and coldest month was 8° C (14° F). Apparently the soils seldom freeze; the minimum temperature measured was -0.5° C (31° F).

Coastal winds in summer are primarily from north to northwest; they strike the coast at an angle at the north end of the range, driving moist air ashore and up the Coquille River Valley. This may influence the superb development of Port-Orford-cedar in this part of its range.

The major causes of damage to Port-Orford-cedar are fungi of the genus Phytophthora (11,13). An exotic root rot caused by P. lateralis was introduced into Coos County about 1952 and has decimated many stands in the area where Port-Orford-cedar grows best. Neither resistance to the rot nor effective treatment of it has been identified. Spores of the fungus are carried by water, so one introduction of the disease may spread to all stands in the watershed below. Natural uphill spread is slow. Infections are carried uphill rapidly or between watersheds in mud on equipment or livestock; they have reached northern Del Norte County, CA. Many isolated stands or those uphill from infection centers, however, may be kept free of the disease by careful exclusion of contaminated machinery, livestock, and nursery stock.

Phytophthora cinnamomi causes major losses to some nurseries and cultivated trees. A white pocket top rot, caused by an unidentified fungus, is a serious problem. Losses to other diseases and to insects are minor (13). Animal damage to planted seedlings is highly variable, sometimes more and sometimes less than on associated conifers (13).

Drought damages native trees on the hotter sites and in inland areas without seepage (13). Port-Orford-cedar is more affected than its associates on these sites. Laboratory experiments show that it is also more susceptible to freezing than most associated trees, although reports of winter damage in the field vary (13). In some instances, no damage occurred at -25° C (-13° F); others report severe damage at -13° C (9° F). Most drastic winter kill occurred in dry, windy, cold weather, desiccation apparently being of considerable consequence. Susceptibility to spring frosts in Great Britain is lower for Port-Orford-cedar than for most of its usual associates. Damage by wind, ice, and snow occurs, but the species does not seem especially susceptible (13).

Port-Orford-cedar effectively recovers from loss of its leader or from extensive killing of foliage at the crown surface. If twigs are killed deeply enough into the crown, however, a tree apparently does not recover because it does not resprout from the "old wood" (13).

Port-Orford-cedar resists moderate air pollution but does poorly where pollution is intense (13). It is more sensitive to nitrous oxide than nitric oxide. Levels of sulfur dioxide that reduce photosynthesis of Port-Orford-cedar have little effect on Douglas-fir and western redcedar.

Although young trees are easily killed by fire, older trees develop thick bark and survive large, deep fire scars (13). In old stands, Port-Orford-cedar seems as tolerant of fire as Douglas-fir.

Pollen and seed cones develop on the same branches of this monoecious species. Reproductive organs are initiated in late spring or summer. They soon protrude beyond the surrounding leaves, and development continues through the summer. The bladderless pollen is formed in late winter in the bright red pollen cones; on the Oregon coast it is shed about mid-March. Fertilization occurs a month or more later, and seeds mature in September or October of the same season (5,13). Each fertile scale of the 7 to 10 scales in the globose cone usually bears 2 to 4 seeds. Cones contain about 20 percent of their weight in seeds (5).

Population Differences Port-Orford-cedar is extremely variable morphologically. Most horticultural cultivars originated as seedling mutations, produced by descendants of apparently only a few introductions to Great Britain (13). Some cultivars are notably more resistant to winter damage and spring frosts than are most, and some root more easily than others.

There is obvious variation in growth rates among seedlings and rooted cuttings from various natural populations; northern coastal sources grow faster than those from inland, and those from productive, dense forest types grow faster than those from open forests on poor soils (13). Relative growth rates of different populations remain the same in culture on both good and poor soils. In culture, differences in nutrient content, and stomatal distribution occur among inland and coastal sources, and the foliar calcium-to-magnesium ratio is lower for a source from an ultramafic area than for those from other soils (13). Local variation occurs in stomatal resistance of seedlings to water loss, but it is not consistent regionally.

Variability in adaptation of individual trees has been noted in Europe. Selections of desirable trees have been made in Great Britain. Apparently no provenance studies of growth have ever been made in field conditions (13). Trials of the species as an exotic may have suffered from the use of a limited seed source; the original introduction to Britain was from the upper Sacramento River, probably an area of slow growth.

Allozyme variability differentiated two inland populations from seven coastal populations in California. The disjunct inland populations contained less variability than the coastal samples. Considerable variation among populations existed in both inland and coastal regions (10).

Hybrids Putative hybrids with Chamaecyparis nootkatensis have been identified in cultivation and in a natural sympatric stand (13); apparently none have been confirmed, however.

After the sapling stage, growth of Port-Orford-cedar is considerably slower than that of Douglas-fir, except on ultramafic substrates where the cedar is usually exceeded in size only by sugar pine (13). In 8- to 26-year-old plantations in the Pacific Northwest, annual height growth of unbrowsed Port-Orford-cedar averaged 0.35 m (1.15 ft), only 86 percent of the mean annual height growth of Douglas-fir; the difference was much greater for browsed trees. In mixed stands, Port-Orford-cedar is usually overtopped by 20 to 25 years. Pole-size stands in the northern part of the range show a large difference in both diameter and height between Douglas-fir and cedar. In one small sample of 53- to 60-year-old trees (age determined at breast height) in coastal Coos County, OR, the Douglas-fir averaged 73 cm (29 in) in d.b.h. and 38 m (125 ft) in height; the cedar averaged 47 cm (19 in) and 28 m (92 ft). Measurements of adjacent stumps on several sites throughout the range showed that the diameter of Port-Orford-cedar was 57 percent that of Douglas-fir at 100 years; however, the difference decreased with age, cedar becoming 74 percent of the diameter of Douglas-fir at 200 years, 78 percent at 300, and 90 percent at 400 (13). Diameter growth of cedar is thus more consistent throughout its life than is that of Douglas-fir.

Size of old-growth cedar trees is variable; much variation is associated with the habitat (and thus the forest community) (13). Early rapid height growth in open stands on ultramafic rocks is not sustained. For example, a sample of forest-grown 90- to 110-year-old trees averaged 30 m (98 ft) in height in the swordfern community, 18 m (59 ft) in the mixed pine community on ultramafics, and 12 to 13 m (39 to 43 ft) in other communities. By 190 to 210 years, heights were 47 m (154 ft) for swordfern, 25 to 29 m (82 to 95 ft) for other communities, but only 21 m (69 ft) for the mixed pine community. At 290 to 310 years, values were 63, 31 to 50, and 29 m, respectively (207, 102 to 164, and 95 ft). Average diameters in old-growth stands range from 42 cm (17 in) (diameter of a tree of mean basal area, mixed pine community) to 86 cm (34 in) (swordfern). Trees more than 100 cm (39 in) in d.b.h. occur in many old-growth stands, and trees of 200 to 250 years may reach 100 cm, but most trees this size are older than 300. On the other hand, one 37-cm (15-in) tree in the mixed pine community was more than 300 years old. Maximum tree age exceeds 560 years (13).

Relatively few yield values exist for young stands. Experience in Great Britain is limited but well documented (13); Port-Orford- cedar is combined with western redcedar in yield tables (table 1). Thinnings begin at 20 to 30 years. Mean annual increment (MAI) peaks at 57 to 72 years. Current annual increment (CAI) increases later than for Douglas-fir and western hemlock on good sites and after its peak decreases more slowly than Douglas-fir but faster than hemlock. On poor sites, CAI starts to increase late than for Douglas-fir but earlier than for hemlock; it decreases after Douglas-fir but before hemlock. On good sites, peak MAI is reached 5 years later than for Douglas-fir and hemlock; on poor sites, it is reached 10 years later than for Douglas-fir but 5 years earlier than for hemlock. In one study, cedar plantations at 60 years were maintained at two to three times the density of Douglas-fir with 1.4 to 1.5 times higher basal area. Sixty-year-old trees averaged 5 to 8 m (16 to 25 ft) shorter and 11 to 20 cm (4 to 8 in) smaller in diameter breast height than Douglas-fir.

Table 1- Attributes of British plantations of Port Orford-cedar and wetern redcedar for the least productive (A) and most productive (B) yield classes¹
Stand
Age
Trees
Height
Diameter Basal Area maintained
after thinning
Cumulative yield A B A B A B A B A B yr no./ha m cm m²/ha m³/ha 20 3,575 2,186   8 13 10 14 28 35   50    232 40 1,730    746 16 24 18 30 42 54 377    901 60    984    451 21 30 26 43 51 66 706 1,439 80    738    347 24 35 32 53 59 76 953 1,838 yr no./acre ft in ft²/acre ft³/acre 20 1,447 885 26   43   3.9   5.5 122 152      715   3,315 40    700 302 52   79   7.1 11.8 183 235   5,388 12,876 60    398 183 69   98 10.2 16.9 222 287 10,090 20,565 80    299 140 79 115 12.6 20.9 257 331 13,620 26,267 ¹Yield classes A and B support maximum mean annual increments of 12.0 and 24.0 m³/ha (171.5 and 343.0 ft³/acre), respectively. Yields include thinnings and are computed for top diameter of 7cm (2.8 in) outside bark (adapted from 13). Volumes reported from young natural stands in Oregon (table 2) and plantations in Europe and New Zealand (13) are in the moderate to low range, compared with British plantations; however, the small top diameter limit used for table 1 and the impurity of natural stands may account for most or all of the difference. Values of MAI for two Oregon stands (table 2) were 13.7 (61 years) and 16.9 m³/ha (57 years) (196 and 242 ft³/acre).

Table 2- Yields from young natural stands of Port-Orford-cedar in western Oregon (7) Total Stand (all species) Port-Orford-cedar
Location Stand
age
Trees Basal
area
Trees Basal
area Average diameter Average height¹
Volume yr no./ha m²/ha no./ha m²/ha cm m m³/ha Coos County Forest 36 3,361   68 2,026   41 16 16 244 Coos County Forest 40 2,817   72 1,359   36 18 16 205 Coos-Curry county line 44 1,853   94 1,507   66 24 22 506 Coos-Curry county line 43 1,705   80 1,384   51 22 22 445 Port Orford 61 1,680 113 1,458   90 28 23 838 Port Orford 57 1,666 126 1,483 115 31 22 966 yr no./acre ft²/acre no./acre ft²/acre in ft ft³/acre Coos County Forest 36 1,360 298 820 179   6.3 51   3,490 Coos County Forest 40 1,140 312 550 157   7.2 52   2,930 Coos-Curry county line 44    750 408 610 287   9.3 73   7,230 Coos-Curry county line 43    690 348 560 222   8.5 72   6,360 Port Orford 61    680 490 590 393 11.1 74 11,980 Port Orford 57    670 548 600 503 12.4 73 13,800 ¹Height of trees of mean basal area. Live volumes of Port-Orford-cedar in old-growth forest sampled in 1935-40 averaged 86 m³/ha (1,229 ft³/acre) in the valley of the South Fork of the Co- quille River (Port Orford Cedar Experimental Forest, 3752 ha or 9,271 acres); the most volume in a 259-ha (640-acre) section was 154 m³/ha (2,201 ft³/acre) (13). Average volume near Bluff Creek, southwest of Orleans, CA, in 1940 was 22 m³/ha (314 W/acre) and the maximum was 47 m³/ha (672 ft³ /acre) on 4922 hectares (12,162 acres). Most volume was in large trees. On coastal terraces, the proportion of Port-Orford-cedar decreased as total volume of old-growth timber increased (13).

Port-Orford-cedar is tolerant of shade and of competition in natural stands (13). Its slow growth beyond the sapling stage results in its being overtopped, but it continues to grow and retains into old age the ability to respond after the dominants die (7). Port-Orford-cedar can reproduce effectively from seed after clearcutting and partial cutting (where a sufficient seed source is present) and under almost all natural forests, and it can be used for under-planting established forest or scrub (13). Some old-growth forest structures resulted from repeated waves of invasion, almost certainly after fires.

Because of its shade tolerance, relatively thick bark, high value, and moderate but consistent growth rate, Port-Orford-cedar might be grown effectively in a partial-cut system in which faster growing associates are removed part way through the rotation. Its litter (with high calcium and high pH) increases soil pH, suggesting that the species may be important in afforestation of moderately acidic soils or for ameliorating the effects of other conifers on soils (13).

Shade tolerance and a narrow crown allow dense stocking in British plantations, and volume for a given height is high (13). Holes left after thinning close slowly, however, and a longer thinning cycle is necessary than for most conifers. Pruning is not useful. Forking of trees has been a problem in many British plantations.

In recent years, plantations of Port-Orford-cedar have not been widely established in the Pacific Northwest outside its native range because of problems with root rot, winter damage, and its slow growth relative to other species (13).

A dense, coastal 50-year-old stand of Port-Orford-cedar on a clay-loam soil had a dense network of fibrous roots at the surface (4). The major horizontal system of surface roots extended up to 7 m (22 ft) from the trunk, producing "humus strivers" (roots with unlignified tips that rise into the surface soil and duff) uniformly along its length. Root systems of adjacent trees intermingled freely; some overlap was likely in trees closer than 12 m (39 ft). Root grafting was common in the main horizontal surface root system, averaging 1.5 grafts per tree; the average graft was 34 cm (13 in) deep between roots 3.8 cm (1.5 in) in diameter. The chance of grafting decreased with both horizontal distance between trees (becoming very small beyond 6 m (20 ft)) and with vertical distance on the slope; however, graft complexes that included several trees sometimes joined trees as far as 12 m (39 ft) apart. Port-Orford-cedar has no taproot but produces vertical sinkers from the horizontal system.

Port- Orford-cedar forms endomycorrhizae with fungi of the family Endogonaceae (13).

Seed production starts when the tree is 5 to 20 years old (5). It can be induced in trees as young as 7 months with sprays of 50 p/m gibberellic acid (the effect is enhanced by Ethrel) with the correct photoperiodic regime (13). (At least 2 weeks of long days are required after gibberellin treatment, followed by at least 2 weeks of short days, followed by long days to allow cone maturation.)

The major peak of seedfall is in the late fall, with a smaller one in spring. Roughly 50 to 60 percent of the seeds fall by mid-January and 85 to 90 percent by May 1 (13); however, some seed is released all year.

Crops of 20,000 to 4,600,000 seeds per hectare (8,094 to 1,862,000/acre) have been measured, with a mean of 829,000 seeds per hectare (335,000/acre) for 30 crops (13). Annual seed production can also be expressed in relation to a unit basal area of the population; 600 to 185,000 with a mean of 40,200 seeds per square meter (56 to 17,187 with a mean of 3,735/ft²) of basal area were produced. Of 30 crops, 5 exceeded 100,000 seeds per square meter (9,290/ft²) of basal area, 6 produced 20,000 to 60,000 seeds per square meter (1,858 to 5,574/ft²), 6 had 10,000 to 20,000 seeds per square meter (929 to 1,858/ft²) , and 13, less than 10,000 seeds per square meter (929/ft²). High seed production per unit basal area occurred in all types of habitats sampled and in both 65-year-old and old-growth forests. No site had good or moderate seed crops 2 years in succession. There seems to be no regional synchronization of large seed crops, however, as occurs in many tree species.

The seeds are small, averaging about 463 000/kg (210,000/lb), with a range of 176 to 1323/g (80,000 to 600,000/lb) (5). Despite having small wings along both sides, the seeds apparently fall more rapidly than many larger conifer seeds. The seed wings appear to aid their flotation on water. Seeds are not a preferred food of rodents in feeding experiments (7), but harvesting of large numbers of cones and removal of seed from them by rodents have been observed in natural stands (13).

Seeds may be stored frozen at less than 10 percent moisture in a sealed container for more than 10 years and retain considerable viability (5,12). One study reports 43 percent germination from seed stored this way for 13 years. Few seeds, if any, germinate later than the first year after dispersal (13).

Seed germination is epigeal; in the natural habitat, it occurred in early June or later in the 1 year it was observed (13). Germination ranged from 11 to 44 percent in natural seed fall trapped on the floor of seven forests. Germination of collected seed is often higher, about 50 percent (5).

Stratification increases germination and seedling growth for some seed lots (13). Red light accelerates germination; far-red light delays it. In laboratory conditions, few seeds germinate below 12° C (12). Sowing in the nursery in March and April is more reliable in England than fall sowing (13). In nursery practice, seeds were sown at 320 to 540/m² (30 to 50/ft² ) and covered by 3 to 6 mm (0.12 to 0.25 in) of soil (5). Shading until midseason may be helpful. A nursery yield of 284,000 usable plants per kilogram of seed (129,000/lb) has been reported (5). Port-Orford-cedar seedlings are easy to grow and establish (13). Seedlings have been planted as 2-0 or 3-0 stock in the United States, and after the first or second year, or as 2-1 stock in Great Britain. Spacing in Britain is 1.4 to 1.5 m (4.5 to 5 ft); recently, in its native range, Port-Orford-cedar has been interplanted with Douglas-fir, at 2.7- to 8-m (9- to 26-ft) spacing (13).

Seedlings are small, with two cotyledons. The next several whorls of leaves are needlelike (5 to 13 whorls in one study); successive whorls gradually develop into the mature, appressed, scalelike foliage differentiated into the flat "facial" and the folded "lateral" leaves (13). Seedling establishment in small experimental plots under a natural canopy was most common where soil had been disturbed but did occur in natural litter; after three growing seasons, only 5 percent of the germinants survived in the most favorable soil conditions. In clearcut or partially cut areas, establishment decreases as ground cover vegetation increases (7).

Seedling growth under a canopy is slow-experimental seedlings are only about 40 mm (1.6 in) tall after their second growing season (13). Seedlings in the open average 36 mm (1.4 in) after 1 year and 78 mm (3.1 in) after 2. Planted 3-0 stock averaged 48 cm (18.8 in) tall after 2 years in the field (7). Natural seedlings established under a canopy take 14 to 31 years to reach breast height (1.37 m; 4.5 ft), compared with 5 to 11 years for trees in clearcuts on nonultramafic soils (13). Early seedling growth sometimes equals that of Douglas-fir in the same clearcut. Seedlings are quite shade-tolerant but do die in dense shade under old-growth forest and do not become established under young, dense, even-aged stands (13). They seem to survive in most understory microsites where western hemlock and white fir can grow.

Port-Orford-cedar often reproduces aggressively from seed. Natural reproduction in clearcuts is usually adequate within 80 to 110 m (262 to 361 ft) of a seed source; however, planting will often be required in large clearcuts (13). Planted seedlings may grow normally in dense competition from gorse or bracken fem. Later growth is intrinsically somewhat slower than that of Douglas-fir (13), and weeding may be necessary to keep Port-Orford-cedar in the upper canopy where maximum growth is possible.

Port-Orford-cedar does not develop winter buds with preformed internodes (13). Elongation continues for as long as 5 months in mild coastal climates; it is more rapid and early in the mixed evergreen zone and equally rapid but late in the Abies concolor zone. Elongation lasts 1.3 to 1.9 times as long as that of Pinaceae on the same site.

Port-Orford-cedar grows on many geologic and soil types: sand dunes; bogs, margins of intermittent streams, and drier sites on ultramafic rocks; and productive soils on sedimentary rocks and diorite (13). The largest trees are found on deep soils weathered from sedimentary rocks in Coos County, OR. The species is also found on sedimentary rocks near the lower Klamath River in California. Throughout much of its range, it is restricted to areas with consistent seepage within a meter of the soil surface. South of Coos County, OR, it is most common on wet spots on ultramafic rocks, especially at lower elevations in the inland and southern parts of its range. Reportedly, Port-Orford-cedar grows on soils in the orders Spodosols, Ultisols, and Inceptisols.

Soils vary from well developed, deep, and productive to skeletal (in seepage areas on peridotite) (13). Average depth to the surface of the C horizon ranges from 32 cm (13 in) in the mixed pine community to 73 cm (29 in) in the rhododendron community. Surface soils vary from sandy loam to clay in texture and often contain much gravel, cobble, or stone; their pH values range from 4.2 to 7.0; cation exchange capacities range from 10 to 42 meq/100 g. Concentrations of macronutrients are nitrogen, 0.12 to 0.25 percent; phosphorus, 2 to 40 p/m; extractable potassium, 36 to 400 p/m; extractable calcium, 0.3 to 10.8 meq/100 g; extractable magnesium, 0.2 to 9.9 meq/100 g. Calcium-to-magnesium ratios are 0.2 to 3.7. Foliar concentrations of nutrients in native saplings are often low (means for 85 saplings at 10 sites were 0.86 percent nitrogen, 0.52 percent potassium, and 0.11 percent phosphorus); in contrast, calcium is usually quite high (1.11 percent) (13). The calcium-to-magnesium ratio of foliage is high, averaging 4.4 and staying above 2 even on ultramafic substrates. Surface soils under Port-Orford-cedar plantations in Great Britain have the highest pH of soils under any conifer tested. Growth in the northern end of the natural range increases with levels of nitrate in the soil. In culture, growth increases with levels of potassium, nitrogen, and calcium in the foliage (13).

In some areas in the northern part of its range, Port-Orford-cedar grows in habitats similar to those of western redcedar (8,9). On sites where both species are present, soils under Port-Orford-cedar are usually more acidic and have higher concentrations of potassium and lower calcium: magnesium ratios. Mineralization of nitrogen is slower in Port-Orford-cedar litter.

Port-Orford-cedar usually grows on concave or sheltered slopes where soil seepage occurs (13). It is most common on slopes, on benches, and in drainageways. Restriction to streamsides and ravines is most obvious inland at low elevations. Stands are most common on northwest, north, and northeast aspects, especially at lower elevations. Port-Orford-cedar grows from just above sea level to about 1500 m (4,900 ft) in the main section of the range, and to 1950 m (6,400 ft) near Mount Shasta (13).

Outside its natural range, the major use of Port-Orford-cedar is as an ornamental (13). As such, it is usually referred to as Lawson cypress. More than 200 cultivars are known, varying in size, shape, foliar morphology, and color. It is suitable for hedges but is usually planted as separate individuals of either full-sized or dwarfed varieties. Its use has declined in some areas because of root rot. Cut branches are used in floral arrangements.

Cuttings may be rooted with relative ease (13). A recommended practice is to use cuttings from tips of major branches from the lower crown of young trees, taken from December to February. Auxin treatments sometimes aid rooting. Natural layering of Port-Orford-cedar occurs occasionally (13). Several vertical limbs of windthrown trees in open stands may develop into separate trunks attached to the horizontal "parent" trunk. Most reproduction, however, is from seed.

Port-Orford-cedar grows in a small area near the Pacific coast, from about latitude 40° 50' to 43° 35' N. in southern Oregon and northern California (13). It is most important on uplifted marine terraces and in the Coast Ranges of southern Coos County and northern Curry County, OR. A secondary concentration is found at high elevations in the upper reaches of the Illinois and Klamath River drainages near the Oregon State boundary. Throughout the rest of its range, Port-Orford-cedar is found as small, scattered populations, most common in the drainages of the middle Rogue, upper Illinois, Smith, lower Klamath, and lower Trinity Rivers. A major inland disjunction includes small populations of the upper Trinity and Sacramento River drainages southwest of Mount Shasta, CA.


- The native range of Port-Orford-cedar.

Cupressaceae -- Cypress family

Donald B. Zobel

Port-Orford-cedar (Chamaecyparis lawsoniana), also called Lawson cypress and Port Orford white-cedar, is known for its grace in ornamental plantings and for its versatile wood. As logs, mostly exported to Japan, it brings higher prices than almost any other conifer in the United States. This valuable tree, however, has a very limited range and an uncertain future. Management of Port-Orford-cedar has become impossible in much of its range since the introduction of a fatal root rot that is still spreading. Old-growth forests are being depleted rapidly, and the use of second-growth forests is complicated because early growth is relatively slow. The commercial future of one of the most beautiful and potentially useful trees will depend on development of silvicultural practices that minimize infection by root rot.

Tree, Evergreen, Monoecious, Habit erect, Trees without or rarely having knees, Tree with bark rough or scaly, Young shoots in flat sprays, Buds not resinous, Leaves scale-like, Leaves opposite, Non-needle-like leaf margins entire, Leaf apex acute, Leaves < 5 cm long, Leaves < 10 cm long, Leaves not blue-green, Scale leaves without raised glands, Scale leaf glands not ruptured, Scale leaves overlapping, Twigs glabrous, Twigs not viscid, Twigs without peg-like projections or large fascicles after needles fall, Berry-like cones orange, Woody seed cones < 5 cm long, Bracts of seed cone included, Seeds tan, Seeds brown, Seeds winged, Seeds equally winged, Seed wings prominent, Seed wings equal to or broader than body.

Chamaecyparis lawsoniana, known as Port Orford cedar or Lawson cypress, is a species of conifer in the genus Chamaecyparis, family Cupressaceae. It is native to Oregon and northwestern California, and grows from sea level up to 4,900 feet (1,500 m) in the valleys of the Klamath Mountains, often along streams.