Associated Forest Cover
provided by Silvics of North America
Sugar pine is a major timber species at middle elevations in the Klamath
and Siskiyou Mountains, Cascade, Sierra Nevada, Transverse, and Peninsula
Ranges. Rarely forming pure stands, it grows singly or in small groups of
trees. It is the main component in the forest cover type Sierra Nevada
Mixed Conifer (Society of American Foresters Type 243) (10) generally
comprising 5 to 25 percent of the stocking. It is a minor component in 10
other types:
207 Red Fir
211 White Fir
229 Pacific Douglas-Fir
231 Port-Orford-Cedar
232 Redwood
234 Douglas-Fir-Tanoak-Pacific Madrone
244 Pacific Ponderosa Pine-Douglas-Fir
246 California Black Oak
247 Jeffrey Pine
249 Canyon Live Oak
In the northern part of its range, sugar pine is commonly associated
with Douglas-fir (Pseudotsuga menziesii), ponderosa pine (Pinus
ponderosa), grand fir (Abies grandis), incense-cedar (Calocedrus
decurrens), western hemlock (Tsuga heterophylla), western
redcedar (Thuja plicata), Port-Orford-cedar (Chamaecyparis
lawsoniana), tanoak (Lithocarpus densiflorus), and Pacific
madrone (Arbutus menziesii). In the central part it is associated
with ponderosa pine, Jeffrey pine (Pin us jeffreyi), white fir
(Abies concolor), incense-cedar, California red fir (A.
magnifica), giant sequoia (Sequoiadendron giganteum), and
California black oak (Quercus kelloggii). Farther south, the usual
associates are Jeffrey pine, ponderosa pine, Coulter pine (Pinus
coulteri), incense-cedar, white fir, and bigcone Douglas-fir (Pseudotsuga
macrocarpa). At upper elevations Jeffrey pine, western white pine (Pinus
monticola), California red fir, and lodgepole pine (P. contorta)
grow with sugar pine. In the Sierra San Pedro Martir, Jeffrey pine and
white fir are the main associates.
Common brush species beneath sugar pine include greenleaf manzanita (Arctostaphylos
patula), deerbrush (Ceanothus integerrimus), snowbrush (C.
velutinus), mountain whitethorn (C. cordulatus), squawcarpet
(C. prostratus), bearclover (Chamaebatia foliolosa), bush
chinkapin (Castanopsis sempervirens), bitter cherry (Prunus
emarginata), salal (Gaultheria shallon), coast rhododendron
(Rhododendron californicum), and gooseberries and currants in the
genus Ribes (11). From a silvicultural standpoint, Ribes spp.
are especially important because they are alternate hosts to the white
pine blister rust fungus (Cronartium ribicola). At least 19
different species grow in the Mixed Conifer Type, of which the Sierra
gooseberry (Ribes roezlii) is most prevalent on more xeric, upland
sites, and the Sierra currant (R. nevadense) on more mesic sites
(35).
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Climate
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Temperature and precipitation vary widely throughout the range of sugar
pine. For equivalent latitudes, temperature decreases and precipitation
increases with elevation, and for equivalent elevations, temperature
increases and precipitation decreases from north to south. Patterns
unifying this variability are relatively warm, dry summers and cool, wet
winters. Precipitation during July and August is usually less than 25 mm
(1 in) per month, and summertime relative humidities are low. Although
water stored in snowpacks and soils delays the onset and shortens the
duration of summer drought, evaporative stress often becomes great enough
to arrest growth in the middle of the season (15). Most precipitation
occurs between November and April, as much as two-thirds of it in the form
of snow at middle and upper elevations (26). Within its natural range,
precipitation varies from about 840 to 1750 mm (33 to 69 in). Because
winter temperatures are relatively mild and seldom below freezing during
the day, considerable photosynthesis and assimilation are possible during
the dormant season, at least partially offsetting the effects of summer
drought (15).
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Damaging Agents
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The pathology of sugar pine is dominated by
white pine blister rust, caused by Cronartium ribicola, a disease serious
enough to severely limit natural regeneration in areas of high hazard, and
thereby alter successional trends. Among commercially important North
American white pines, sugar pine is the most susceptible. Infected
seedlings and young trees are inevitably killed by cankers girdling the
main stem.
Blister rust was introduced into western North America shortly after the
turn of the century at a single point on Vancouver Island and has since
spread eastward throughout the Inland Empire and south through the
Cascade, Klamath, North Coast, and Sierra Nevada Ranges. It has not yet
been found in the Transverse or Peninsular Ranges of southern California,
even though alternate host species are abundant there. Within the range of
sugar pine, conditions for infection are not nearly so uniform as for
western white pine in the Inland Empire. Incidence and intensity of
infection on sugar pine are highest in Oregon and northern California and
become progressively less to the south, as climate becomes warmer and
drier. Within any area, however, hazard varies widely and depends on local
site conditions. These are complex, but two of the most important factors
are the duration of moisture retention on foliage following rain, fog, or
dew, and the distribution and density of the alternate hosts, currant and
gooseberry bushes (Ribes spp.). Thus, cool north slopes
are more hazardous than warm south slopes, and relatively humid stream
bottoms and lakesides are more hazardous than upland sites. In the Cascade
Range and Sierra Nevada of northern California, infection averaged two to
three times higher near stream bottoms than on adjacent slopes (4).
Attempts to control blister rust by chemical therapy or eradicating
alternate hosts have been abandoned as impractical and ineffective. Except
on highly hazardous sites, sugar pine in natural stands can be effectively
managed by judiciously selecting leave trees with cankers relatively far
from the bole and by pruning cankers in the lower crown (4).
Plantations are a much more serious problem. The microenvironmental
changes on a site following clearcutting-including dew formation on
foliage and the rapid regeneration of alternate host Ribes spp.
greatly augment the probability of rust intensification and spread on
both hosts. Uniform age and stocking make sugar pine plantations
vulnerable to nearly total destruction for 20 years or longer. Genetically
resistant sugar pines in mixture with other conifers offer the most
promising solution.
Dwarf mistletoe (Arceuthobium californicum) may seriously damage
infected trees by reducing growth in height, diameter, and crown size, and
predisposing weakened trees to attack by bark beetles. Extending
throughout the range of sugar pine, except for isolated stands in Nevada,
the south Coast Ranges of California, and Baja California, this mistletoe
was found in only 22 percent of the stands examined and on only 10 percent
of the trees in those stands. Spread is slow and can be controlled by
sanitation cutting (20,42).
A needle cast caused by Lophodermella arcuata is occasionally
and locally damaging. Root diseases caused by Armillaria mellea,
Heterobasidion annosum, and Verticicladiella wageneri are
capable of killing trees of all ages and sizes but, though widespread, are
usually at endemic levels. Several trunk and butt rots attack sugar pine
but are usually confined to mature and overmature trees (2,21).
Several root and damping-off pathogens cause severe damage to sugar pine
in nurseries, with annual losses up to 50 percent (45). In approximate
order of importance, these are Fusarium oxysporum, Macrophomina
phaseoli, and species of Pythium, Phytophthora, and Rhizoctonia.
In addition to causing direct losses in the nursery, these diseases
may reduce field survival of planted seedlings in more stressful
environments by causing stunting and chlorosis. Nursery fumigation
controls most of the organisms involved but is least effective on Fusarium.
A simple and promising alternative control method is early sowing of
stratified seed. Soil temperatures in late winter and early spring permit
seed germination and root development but are still cool enough to inhibit
fungal growth.
Sugar pine hosts many different insects, but the mountain pine beetle
(Dendroctonus ponderosae) is of overwhelming importance. This
insect can cause widespread mortality, often killing large groups of trees
(48). Several other bark-feeding insects contribute directly or indirectly
to mortality in sugar pines, particularly after periods of drought. Death
results from predisposing trees to mountain pine beetle. The red
turpentine beetle (Dendroctonus valens) is usually restricted to
small areas near the root crown but during drought may extend two or more
meters up the bole, destroying the entire cambium. The California
flatheaded borer (Melanophila californica) usually attacks
decadent and unhealthy trees, but trees under heavy moisture stress are
also vulnerable. The California fivespined ips (Ips paraconfusus)
is only capable of penetrating thin bark in sugar pine. Small trees are
often killed, but large trees only top-killed (16).
The sugar pine cone beetle (Conophthorus lambertianae) can be
extremely destructive to developing second-year cones, destroying up to 75
percent of the crop in some years. Since stunted cones are apparent by
mid-June, the extent of the crop loss can be assessed well before cone
collection. The sugar pine scale (Matsucoccus paucicicatrices) occasionally
kills foliage and branches, predisposing trees to bark beetle attack. The
dead "flags" resulting from heavy attack mimic advanced symptoms
of white pine blister rust. Occasionally, the black pineleaf scale (Nuculaspis
californica) defoliates sugar pine at midcrown, weakening the tree.
These scale attacks are often associated with industrial air pollution or
heavy dust deposits on foliage (16).
Among its coniferous associates, sugar pine is the most tolerant to
oxidant air pollution (34), while intermediate in fire tolerance (39) and
frost tolerance (43,44). It is less tolerant of drought than most
companion species with which it has been critically compared, including
knobcone (Pinus attenuata) and Coulter pines (50,51), ponderosa
pine, Douglas-fir, incense-cedar, and grand fir (40).
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Flowering and Fruiting
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Sugar pine is monoecious. Reproductive
buds are set in July and August but are not discernible until late in the
next spring. Time of pollination ranges from late May to early August,
depending on elevation, and to a lesser extent on latitude.
Female strobili are 2.5 to 5.0 cm (1 to 2 in) long at time of
pollination and double in size by the end of the growing season.
Fertilization of eggs by male gametes takes place late the following
spring, about 12 months after pollination. By this time, the seed is at
its final size with a fully developed coat. Conelet elongation continues
during the second season until maturation in late summer. Mature sugar
pine cones are among the largest of all conifers, averaging 30 cm (12 in)
and ranging up to 56 cm (22 in) long. Dates of cone opening range from
mid-August at low elevations to early October at high elevations
(12,19,32).
Cone production starts later and is less prolific in sugar pine than in
its associates. During a 16-year study in the central Sierra, fewer than 5
percent of sugar pines less than 20 cm (8 in) in d.b.h., and 50 percent
less than 31 cm (12 in) in d.b.h., produced cones. Of trees 51 cm (20 in)
or more, 80 percent produced cones, and dominant trees produced 98 percent
of the total. Intervals between heavy cone crops averaged 4 years and
ranged from 2 to 7 (12).
Loss of sugar pine cones is heavy; the probability of a pollinated
conelet developing to maturity is only 40 to 50 percent. Predation by the
sugar pine cone beetle (Conophthorus lambertianae) can cause up to
93 percent loss. Douglas squirrels and white-headed woodpeckers also take
a heavy toll (7,11,17).
Spontaneous abortion of first-year conelets is high. Observations of
control-pollinated trees in the Klamath Mountains showed that 19 percent
of female strobili were lost 5 to 12 weeks after bagging, with no obvious
signs of insect or pathogen-caused damage (41). The amount of abortion
varied from 15 to 85 percent among trees, for both bagged and unbagged
strobili. Since this pattern was consistent in successive years, a genetic
cause was suggested.
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Genetics
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Sugar pine is one of the more genetically variable members of the genus.
Average heterozygosity of specific genes coding for seed proteins
(isozymes) was 26 percent, a value near the upper range (0 to 36 percent)
of pines studied so far (6). How adaptive variation is distributed over
the range of environments encountered in over 14° of latitude and
2000 m (6,560 ft) of elevation is largely unknown, however, because of a
lack of field data from provenance or progeny tests.
In a 3-year nursery trial, pronounced differences in height and diameter
growth were found among seedlings of five seed sources sampled along an
elevational transect on the west slope of the Sierra Nevada (18). The
fastest growing seedlings were from the lower-middle elevation (1100 m or
3,595 ft) and were twice the height of those from the highest elevation
(2195 m or 7,200 ft). Except for the source from the lowest elevation (770
m or 2,525 ft), which ranked second, growth varied inversely with
elevation. Elevation of the seed source accounted for 52 percent of the
total variance among seedlings, and the component of variance for families
within stands was a substantial 16 percent. More comprehensive nursery
trials, of families from seed parents ranging from southern California to
southern Oregon, showed similar trends (27). Greatest growth was expressed
in seedlings from intermediate elevations in the central Sierra Nevada, a
result consistent with observations in natural stands. Thus, genetic
adaptation to climatic variables associated with elevation is clearly
evident in sugar pine, requiring a close match between seed source and
planting site in artificial regeneration. The degree of variability
expressed among progenies of different seed parents within seed collection
zones indicates that selection for rapid early growth should be effective.
Resistance to white pine blister rust is strongly inherited, and three
different kinds have been recognized (29). A rapid, hypersensitive
reaction to invading mycelium is conditioned by a dominant gene. This
gene, which occurs at variable but relatively low frequencies throughout
the range of sugar pine, is highly effective against most sources of
inoculum. A race of blister rust capable of overcoming this gene was
discovered in a plantation in the Klamath Mountains (30), but evidently
had not spread from this site 10 years after it was found (31). In certain
families, another kind of resistance is expressed by slower rates of
infection and mortality, fewer infections per tree, and by a higher rate
of abortion of incipient infections. This "slow rusting" is
apparently inherited quantitatively and, while less dramatic than single
gene resistance, may be more stable to variation in the pathogen in the
long term. Probably two or more generations of selection and breeding will
be necessary to accumulate enough genes in parental stock to make this
kind of resistance usable in commercial silviculture. A third kind of
resistance is age-dependent. In common garden tests, infection among
grafted clones from mature trees ranged from 0 to 100 percent, yet
offspring from the apparently resistant clones were fully susceptible.
Although not understood, the mechanisms and inheritance of mature tree
resistance are very strong and could play a significant role in
stabilizing resistance over a rotation. Since all three kinds of
resistance are inherited independently, there is a real promise for an
enduring and well-buffered genetic control of this most destructive
disease.
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Growth and Yield
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Veteran sugar pines often reach great size.
Large trees have commonly scaled 114 to 142 m³ (20,000 to 25,000 fbm,
Scribner log rule), with a record of 232 m³ (40,710 fbm). A "champion,"
located on the North Fork of the Stanislaus River in California, measured
65.8 m (216 ft) tall and 310 cm (122 in) in d.b.h., but trees up to 76 m
(250 ft) tall have been reported (11,36). These and previous champions of
this century are dwarfed by the first sugar pine measured by David Douglas
and described in his diary (37): "Three feet from the ground, 57 feet
9 inches in circumference; 134 feet from the ground, 17 feet 5 inches;
extreme length 215 feet."
Early growth of sugar pine is slow compared with ponderosa pine, but
growth rates accelerate in the pole stage and are sustained for longer
periods than those of common associates. Consequently, sugar pines are
usually the largest trees, except for giant sequoia, in mature and
old-growth stands. On better sites annual growth increments in basal area
of 2.5 percent and more can be sustained up to stem diameters of 76 to 127
cm (30 to 50 in) or for 100 to 150 years (11). Growth of sugar pine is
best between 1370 and 1830 m (4,500 and 6,000 ft) in the central Sierra
Nevada, between the American and San Joaquin Rivers.
In young mixed conifer stands, sugar pine often constitutes a relatively
small proportion of the total basal area but contributes
disproportionately to growth increment. On the El Dorado National Forest
in the western Sierra Nevada, in stands ranging in age from 50 to 247
years, the sugar pine component was only 6 to 7 percent (range: 3 to 14
percent) of the average basal area, but its average annual basal area
growth was 11.3 percent (range: 2 to 35 percent) of the stand total. A
similar relationship was found on the Plumas National Forest in the
northern Sierra Nevada: in stands from 58 to 95 years old, average basal
area of sugar pine was 7 percent (3 to 16), but 10-year growth was more
than 12 percent (6 to 19). Ten-year volume increment in mixed conifer
stands from 40 to 80 years old was greater for sugar pine than for
Douglas-fir, white fir, ponderosa pine, and incense-cedar in each of five
basal area categories (9). Mean increment for sugar pine was 4.1 percent,
compared to 3.1 percent for all others.
Yields of sugar pine are difficult to predict, because it grows in mixes
of varying proportion with other species. In the old-growth forest, the
board foot volume of sugar pine was 40 percent of total in stands
dominated by ponderosa pine and sugar pine. In exceptional cases on very
small areas, yields were 2688 m³/ha (192,000 fbm/acre) (11). Yield
tables for young growth are based on averages for all commercial conifers
and assume full stocking (8). The data base is limited, so the tables are
at best a rough guide. Realistically, yields may reach 644 m³/ha
(46,000 fbm/acre) in 120 years on medium sites, and Up to 1190 m³/ha
(85,000 fbm/acre) in 100 years on the best sites, with intensive
management (11).
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Reaction to Competition
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Sugar pine tolerates shade better than
ponderosa pine but is slightly less tolerant than incense-cedar and
Douglas-fir and much less so than white fir (14). A seral species, it
becomes less tolerant with age, and overtopped trees decline unless
released (11). Thus, dominant sugar pines in old-growth stands were
probably dominant from the start, or released by natural causes early in
life. White fir would usually be the climax species in mixed conifer
forests in the absence of any natural disturbance; however, fire, insects,
disease, and other agents are natural and pervasive features of these
forests. Such disturbances frequently cause gaps, in which the relatively
tolerant sugar pine is adapted to grow (14). For these reasons, sugar pine
is often adapted to regenerate in a shelterwood silvicultural system (33).
Competition from brush severely retards seedling establishment and
growth. Only 18 percent of seedlings starting under brush survived over a
period of 18 to 24 years, and after 10 years the tallest seedlings
measured were only 29 cm (11.4 in). Given an even start with brush,
however, seedlings can compete successfully (11).
Light shelterwoods can protect seedlings of sugar pine and white fir
against frost, which seldom affects ponderosa and Jeffrey pines, and
provide them with a competitive advantage because of their greater
tolerance to shade (13,43,44). On the other hand, young sugar pines
stagnate beneath an overstory and in competition with root systems of
established trees or brush. But because they respond well to release, the
basal area increment of sugar pines is often double that of companion
species after heavy thinnings (33). Thus, skill in the amount and timing
of overstory removal is a key factor in successful silvicultural
management of sugar pine.
Sugar pine does not self-prune early, even in dense stands, and
mechanical pruning is necessary to ensure clear lumber of high quality.
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Rooting Habit
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Sugar pine develops a deep taproot at an early
age.
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Seed Production and Dissemination
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Mature trees produce large
amounts of sound seeds. In a study of 210 trees in 13 stands in the
central and northern Sierra Nevada, the average number of sound seeds per
cone was 150, with individual trees ranging from 34 to 257. Higher numbers
of seeds per cone (209 to 219) have been reported, but whether the count
was based on sound or total seeds was not specified. In good crop years,
the proportion of sound seeds is usually high (67 to 99 percent) but in
light crop years can fall as low as 28 percent (7,12).
Cones are ripe and start to open when their color turns light brown and
specific gravity (fresh weight basis) drops to about 0.62. Seed shed may
begin in late August at low elevations and at higher elevations is usually
complete by the end of October (11).
Seeds are large and heavy, averaging 4,630 seeds per kilogram
(2,100/lb). Since their wings are relatively small for their size, seeds
are not often dispersed great distances by wind, and 80 percent fall
within 30 m (100 ft) of the parent tree. Birds and small mammals may be an
important secondary mechanism of dispersal, even though they consume most
of the seeds they cache. In good seed years, large amounts of seed fall,
with estimates ranging from 86,500 to more than 444,800/ha (35,000 to
180,000/acre) in central Sierra Nevada stands (11,32).
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Seedling Development
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Sugar pine seeds show dormancy, which can
be readily broken by stratification for 60 to 90 days or by removal of the
seed coat and inner papery membrane surrounding the seed. Germination of
fresh seed is uniformly rapid and high, exceeding 90 percent if adequately
ripened, cleaned, and stratified. Viability may decline rapidly with time
in storage at temperatures above freezing, but deep-frozen seed maintains
viability much longer (1,32,47).
On unprepared seed beds, seed-to-seedling ratios are high (244 to 483).
Soil scarification reduced the ratio to 70 in one case, and scarification
with rodent poisoning dropped it to 38 in another (12).
Seedling losses are continual and only 20 to 25 percent of the initial
germinants may survive as long as 10 years. Drought may kill up to half of
the first-year seedlings. Cutworms and rodents, which eat seeds still
attached to seedling cotyledons, also take their toll (11,12). Seedlings
infected by blister rust rarely survive more than a few years.
Germination is epigeal (32). Seedlings rapidly grow a deep taproot when
seeds germinate on bare mineral soil. In one comparison, taproots
penetrated to an average depth of 43 cm (17 in) on a bare sandy soil, but
only half as deep when the soil was overlain with duff (11). Lateral roots
develop near and parallel to the soil surface, often growing downward some
distance from the stem. In heavier, more shallow soils, laterals are often
larger than taproots. During the second season, laterals commonly
originate on the lower taproot and occupy a cone of soil which has its
base at the tip of the taproot. After 2 years on three different soil
types in Oregon, the taproots of natural sugar pine seedlings ranged from
56 to 102 cm (22 to 40 in), were significantly deeper than those of
Douglas-fir and grand fir, but shorter than those of ponderosa pine and
incense-cedar. Lengths of main lateral roots showed the same species
differences. Top-to-root ratios for sugar pine ranged from 0.17 to 0.28
(length) and from 1.33 to 1.60 (dry weight) (46).
Seasonal shoot growth starts later and terminates earlier in sugar pine
than in its usual conifer associates, except white fir. At middle
elevations in the central Sierra Nevada, shoot elongation begins in late
May, about 2 weeks after ponderosa pine and a month before white fir, and
lasts about 7 weeks. Radial growth begins about 6 weeks earlier than shoot
growth and extends throughout the summer (11).
Planting of sugar pine has not been so easy or successful as for some of
the yellow pines. Although reasons for the many recorded failures are
often complex, lower drought tolerance may be one of the factors. During
natural regeneration, the ability of sugar pine seedlings to avoid summer
drought by rapidly growing a deep taproot largely compensates for the
relative intolerance of tissues to moisture stress (38).
To survive the first summer after planting, seedlings must have the
capacity to regenerate vigorous new root systems. For other western
conifers, root growth capacity is conditioned by particular combinations
of nursery environment and time in cold storage after lifting; these
requirements are species and seed-source specific (22,24,38). Although
patterns of root growth capacity have not been worked out for sugar pine,
it is clear that amounts of root growth are substantially less for sugar
pine than for its associates (23).
Early top growth of sugar pine is not so rapid as that of western yellow
pines, and 1-year stock is too small for planting when seed is sown in
May, for years the tradition in California nurseries. Root diseases, to
which young sugar pines are unusually vulnerable, can compound the problem
by weakening seedlings that survive, thus reducing their chances of
establishment on the site. Sowing stratified seed in February or March
extended the growing season and produced healthy seedlings of plantable
size in one season (23). A more expensive alternative to bareroot stock
that holds some promise is containerized seedlings grown under accelerated
growth regimes (28).
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Soils and Topography
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Sugar pine grows naturally over a wide range of soil conditions
typically associated with conifer-hardwood forests. Soil parent materials
include rocks of volcanic, granitic, and sedimentary origin and their
metamorphic equivalents and are usually not of critical importance. Soils
formed on ultrabasic intrusive igneous rocks such as peridotite and
serpentinite, however, have low calcium-to-magnesium ratios and usually
support open conifer stands of inferior growth and quality. Nevertheless,
sugar pine is often the dominant conifer on the more mesic of these sites
(39,40).
Because site productivity is a function of several environmental
variables-edaphic, climatic, and biotic-it is difficult to relate parent
material groups or particular soil series with specific productivity
classes, especially when they span wide ranges of elevation and latitude.
Other factors being equal, the main edaphic influences on conifer growth
are soil depth and texture, permeability, chemical characteristics, and
drainage and runoff properties (5).
The most extensive soils supporting sugar pine are well drained,
moderately to rapidly permeable, and acid in reaction. Soils derived from
ultrabasic rocks are very slightly acid to neutral (pH 7.0). In general,
acidity increases with soil depth. Several edaphic properties are
influenced by the degree of soil profile development. Soil porosity,
permeability, and infiltration rate decrease with more developed profiles,
while water-holding capacity, rate of run-off, and vulnerability to
compaction increase.
Sugar pine reaches its best development and highest density on mesic
soils of medium textures (sandy loam to clay loams) but ranges into the
lower reaches of frigid soils when other climatic variables are suitable.
These soils are found most commonly in the order Ultisols and Alfisols.
The best stands in the Sierra Nevada grow on deep, sandy loam soils
developed from granitic rock. In the southern Cascade Range the best
stands are on deep clay loams developed on basalt and rhyolite. In the
Coast Range and Siskiyou Mountains in California and Oregon, the best
stands are on soils derived from sandstone and shale.
Much of the terrain occupied by sugar pine is steep and rugged. Sugar
pines are equally distributed on all aspects at lower elevations but grow
best on warm exposures (southern and western) as elevation increases.
Optimal growth occurs on gentle terrain at middle elevations.
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Special Uses
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Upper grades of old-growth sugar pine command premium prices for
specialty uses where high dimensional stability, workability, and affinity
for glue are essential. The wood is light (specific gravity, 0.34 ±
0.03) (3), resists shrinkage, warp, and twist, and is preferred for finely
carved pattern stock for machinery and foundry casting. Uniformly soft,
thin-celled spring and summer wood and straight grain account for the ease
with which it cuts parallel to or across the grain, and for its
satin-textured, lustrous finish when milled. Its easy working qualities
favor it for molding, window and door frames, window sashes, doors, and
other special products such as piano keys and organ pipes. Wood properties
of young growth are not so well known. Pruning would undoubtedly be
required to produce clear lumber during short rotations.
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Vegetative Reproduction
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Sugar pine does not sprout, but young
trees can be rooted from cuttings. The degree of success is apparently
under strong genetic control. In one trial the proportion of cuttings that
rooted from different ortets from 3 to 6 years old ranged from 0 to 100
percent (27). As for most conifers, rootability diminishes rapidly with
age of donor tree. Grafts, however, can be made from donors of all ages,
with success rates from 70 to 80 percent common. Problems of
incompatibility, frequent in some species such as Douglas-fir, are rare in
sugar pine.
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Distribution
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Sugar pine extends from the west slope of the Cascade Range in north
central Oregon to the Sierra San Pedro Martir in Baja California
(approximate latitude 30° 30' to 45° 10' N.). Its distribution
is almost continuous through the Klamath and Siskiyou Mountains and on
west slopes of the Cascade Range and Sierra Nevada, but smaller and more
disjunct populations are found in the Coast Ranges of southern Oregon and
California, Transverse and Peninsula Ranges of southern California, and
east of the Cascade and Sierra Nevada crests. Its southern extremity is an
isolated population high on a plateau in the Sierra San Pedro Martir in
Baja California. Over 80 percent of the growing stock is in California
(49) where the most extensive and dense populations are found in mixed
conifer forests on the west slope of the Sierra Nevada.
In elevation, sugar pine ranges from near sea level in the Coast Ranges
to more than 3000 m (10,000 ft) in the Transverse Range. Elevational
limits increase with decreasing latitude, with typical ranges as follows:
Cascade Range
335 to 1645 m (1,100 to 5,400 ft)
Sierra Nevada
610 to 2285 m (2,000 to 7,500 ft)
Transverse and Peninsula Ranges
1220 to 3000 m (4,000 to 10,000 ft)
Sierra San Pedro Martir
2150 to 2775 m (7,065 to 9,100 ft)
- The native range of sugar pine.
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Brief Summary
provided by Silvics of North America
Pinaceae -- Pine family
Bohun B. Kinloch, Jr. and William H. Scheuner
Called "the most princely of the genus" by its discoverer,
David Douglas, sugar pine (Pinus lambertiana) is the tallest and
largest of all pines, commonly reaching heights of 53 to 61 m (175 to 200
ft) and d.b.h. of 91 to 152 cm (36 to 60 in). Old trees occasionally
exceed 500 years and, among associated species, are second only to giant
sequoia in volume. For products requiring large, clear pieces or high
dimensional stability, sugar pine's soft, even-grained, satin-textured
wood is unsurpassed in quality and value. The huge, asymmetrical branches
high in the crowns of veteran trees, bent at their tips with long,
pendulous cones, easily identify sugar pine, which "more than any
other tree gives beauty and distinction to the Sierran forest" (25).
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- USDA, Forest Service