Northwest Trees: Identifying and Understanding the Region's Native Trees

PART ONE

Conifers

Western white pine

WESTERN WHITE PINE

Pinus monticola | Pine family (Pinaceae)

Across most of its natural distribution, from central British Columbia to California’s Sierra Nevada, western white pine grows scattered among forests dominated by firs and hemlocks. The pine stands out as a handsome tree with checkered bark and a slender, open crown adorned with long, dangling cones that contrasts with its thick-canopied associates.

Western white pine once dominated the forest over large areas of northern Idaho. Its great columnar trunks stood close together and soared upward, supporting a canopy 200 feet (60 m) high. These were the preeminent lumber-producing timberlands of the Rocky Mountains. Over much of the last century, heavy logging, devastating wildfires, a crippling fungal disease, and an epidemic of bark beetles laid waste to Idaho’s magnificent white pine forest. With the help of geneticists and foresters, this beleaguered species is making a comeback in and beyond northern Idaho.

WHERE IT GROWS

Western white pine grows between sea level and about 5000 feet (about 1500 m) elevation in southwestern British Columbia and western Washington. It also inhabits moist areas of the Blue Mountains in eastern Washington and Oregon. In Oregon, the species’ affinity for moist sites generally confines it to between 2000 and 6000 feet (600 and 1800 m) in the Cascades and coastal ranges. Near its southern limits, in the Sierra Nevada, it finds suitably cool and moist conditions between about 7000 and 10,500 feet (2100 and 3200 m) elevation. Western white pine also occupies the moist, inland maritime forests of southeastern British Columbia, northeastern Washington, northern Idaho, and northwestern Montana as far east as Glacier National Park.

Western white pine cone

APPEARANCE

Young western white pines have narrow, open crowns made up of very regularly spaced whorls (distinct layers) of branches arising from the same level on the main stem. One can estimate the age of a young tree by counting the annually produced branch whorls.

Even relatively young western white pines commonly bear some of the long, slender cones. The cones, often used in wreaths and other decorations, are 6 to 11 inches (15 to 28 cm) long, slightly curved, and covered with thin, pitchy scales. The cones, which remain intact on the forest floor for a few years, are useful for identification of tall trees whose foliage is out of reach.

All white pines—including sugar, whitebark, and limber pine— bear their needlelike leaves in bundles (fascicles) of five. Western white pine needles are noticeably more slender, flexible, and whitish blue green than those of whitebark pine, which sometimes grows nearby at high elevations. Western white pine needles are lined with minute teeth—detected by feeling them—while needles on whitebark pine are smooth. Sugar pine, an associated species in Oregon, has needles that are stiffer, somewhat plumper, and darker in color (bluish green).

Mature western white pine trees have bark that appears checkered or cut into small, regular units, unlike any other northwestern tree. Still another notable feature of old trees, especially those in the Northern Rockies, is the way uppermost boughs often stretch out and upward.

ECOLOGICAL ROLE

Western white pine grows in relatively humid regions or in moist sites in the mountains. Although it is intermediate in shade tolerance—the ability to compete with other species in a dense forest—its principal associates include highly shade-tolerant true firs and hemlocks. Thus, in order to compete for growing space, western white pine requires occasional disturbances, notably fire. Historically, white pine benefited from its ability to survive understory fires that burned along the ground at low intensity and killed many of the firesensitive firs and hemlocks. Stand-replacement fires killed most trees but often favored western white pine because it regenerates well in burned areas—sometimes from seeds surviving in green cones in tall trees. Western white pine commonly outgrows its competitors in the aftermath of fire, logging, or other disturbances.

This species also succeeds by being exceptionally well adapted to poor soils. On gravelly soils compacted by the massive continental glacier that inundated the Puget Sound area, white pines outgrow even the ubiquitous coastal Douglas-fir, attaining diameters of 36 inches (90 cm) by the time Douglas-fir of the same age are half that thick. Western white pine also thrives at the margins of bogs on the Olympic Peninsula. On high, stony ridges in the southern Cascades and Sierra Nevada, western white pine often develops into a stout, rugged sentinel rising out of the boulders.

HUMAN HISTORY

Ethnobotanists who have studied tribal uses of plants throughout the Greater Northwest report that western white pine’s resinous gum was chewed to relieve or treat coughing (Moerman 1998). Native peoples coated whaling and fishing equipment and fastened arrowheads on shafts with the tree’s pitch. This species was apparently utilized less than other pines that bear large seeds or grow in dry regions where the extensively useful western redcedar wasn’t available. However, aboriginal peoples weren’t mass-producing lumber.

Pioneer lumbermen considered western white pine and its close relative eastern white pine (Pinus strobus), native to eastern North America, among the world’s finest softwoods. Eastern white pine produced the prime lumber used in early Colonial houses as well as square timbers and thousands of huge masts for sailing ships. The English monarchy even blazed certain prime specimens with a broad arrow to reserve them for the Royal Navy.

The wood of both eastern and western white pines is light in color and weight but comparatively strong. Its grain is often so straight and even that the wood can be sliced across the grain with ease. The wood takes nails without splitting, works well, is not very resinous, and takes finishes nicely. It has historically been prized for window and door frames and moldings. It is an outstanding wood for carving. A favorite whittler’s project is to take a block of white pine and fashion it into a chain composed of many interlocking links—an operation hard for the novice even to visualize.

Reopening a trail in northern Idaho’s white pine forest after the 1910 fire (photo courtesy of US Forest Service, Region 1)

Western white pine has an epochal relationship to the development of forestry in western North America. By 1880, unregulated harvest had removed much of the original eastern white pine forest, and lumbermen’s attention shifted to the even larger western white pine timber found in the Coeur d’Alene and Saint Joe River drainages of northern Idaho (Strong and Webb 1970). This was before the forest reserves (later called national forests) were established, at a time when government policy favored disposal of western lands to aid settlement and development. Two transcontinental railroads that passed through northern Idaho, with their branch lines, totaled 4000 miles (6400 km) of track and required 10 million ties, many of which were milled from western white pine. By the early 1900s, sawmills in the Coeur d’Alene River drainage alone were annually producing up to half a billion board feet of largely white pine lumber, enough to build 50,000 small houses. One big mill operated by the Ohio Match Company sawed white pine into planks that were cut up into wooden matchsticks!

Uncontrolled logging might have cleared off all the primeval western white pine forests, as had happened with eastern white pine. Fortunately, the era of conservation intervened—aided by President Theodore Roosevelt and Chief Forester Gifford Pinchot. Millions of acres were placed into federal forest reserves, but the problem of what to do about wildfires plagued efforts to protect the forests. A crisis arose in August 1910, when a violent windstorm fanned multiple fires into a conflagration that engulfed 3 million acres (1.2 million ha), including part of the town of Wallace, Idaho, and a few backwoods settlements. This disastrous fire centered in Idaho’s white pine region became the impetus for the federal forestry campaign to eliminate fire. Two generations later, in the late 1970s, forest agencies recognized that attempts to exclude fire from forests were ultimately counterproductive, and they adopted new policies promoting comprehensive management of fire and fuels—a policy that is practiced in some areas but not in others (Arno and Allison-Bunnell 2002).

Another monumental event in 1910 directly impacted western white pine. A Eurasian disease, white pine blister rust (Cronartium ribicola), was accidentally imported to Vancouver, British Columbia, on eastern white pine seedlings that had been grown in France (McDonald and Hoff 2001). By the 1920s, blister rust had spread eastward, via windblown spores, to the white pines of northern Idaho. The rust fatally damages white pine trees (including whitebark, limber, and sugar pines). In the 1930s, federal forestry agencies responded to this worsening plague by launching a multimillion-dollar program to save white pines. For three decades, thousands of people were employed to grub out and chemically poison currant and gooseberry bushes (genus Ribes) from British Columbia and California and eastward to Glacier and Yellowstone National Parks. By thus destroying this alternate host necessary for completion of the blister rust’s life cycle, foresters hoped to save white pines.

However, rust spores can be carried many miles downwind in moist air masses. The Ribes eradication program proved futile, as did a direct chemical attack on blister rust. In 2005, Forest Service pathologists in Moscow, Idaho, discovered that two species of native forest herbs—a lousewort (Pedicularis) and a paintbrush (Castilleja)—can serve as alternate hosts for blister rust. Since the 1960s, efforts have concentrated on breeding the small percentage of white pines that exhibit natural resistance to blister rust. Since 1970, millions of naturally resistant western white pine seedlings have been planted and have generally grown well on logged sites in northern Idaho and adjacent areas. Also, natural rust resistance seems increasingly evident in wild young white pines growing on logged, burned, or otherwise disturbed sites, even in areas where the species is less abundant. Periodic disturbance by logging or fire that opens up the forest provides this western white pine an opportunity to regenerate in large numbers, which allows rustresistant individuals to get established and pass on some of their genetic resistance to subsequent generations. Western white pine is probably at greatest risk in natural areas west of the Cascade crest, where fire is still effectively excluded. Logging, which could create new habitat for white pine, is not allowed in most natural areas.

SUGAR PINE

Pinus lambertiana | Pine family (Pinaceae)

Sugar pine is often described in poetic terms as the most regal of the world’s 100 or so species of pine. It is the largest of all the pines, with old trees commonly attaining 4 to 8 feet (1.2 to 2.4 m) in diameter and over 200 feet (60 m) in height, and it bears huge, pendant cones at the tips of great, spreading limbs. The upper-crown branches on old trees commonly reach out 25 feet (8 m) or more, as if to demonstrate dominion over the other forest species. The legendary aura associated with sugar pine (see Human History below) began with explorer David Douglas’s heroic and perilous discovery of this forest giant in the remote mountains of southwestern Oregon. In addition to its inspirational image, sugar pine has long served humans as a source of sustenance and high-quality lumber.

WHERE IT GROWS

Sugar pine grows on relatively moist sites at middle elevations in the mountains of Oregon and California, where it is part of a diverse mixed conifer forest. On the western slope of the Cascades east of Eugene, Oregon, it is usually found between elevations of 1700 and 3700 feet (500 and 1100 m), but in Oregon’s eastern and southern Cascades and in the Siskiyous, it ascends to 5000 feet (1500 m) or higher. Small populations of sugar pine are scattered northward along the Cascades a few miles past Mount Jefferson. The species is more abundant farther south, in forests west of Crater Lake and in the Siskiyous. Small populations also occupy isolated higher mountains east of the Cascades, south of Bend, Oregon. Sugar pine becomes more abundant along the western slope of the Sierra Nevada in California.

Sugar pine

APPEARANCE

Young sugar pines have broad, conical canopies extending down near the ground, with distinctive bluish-green foliage made up of 3-to-4-inch-long (8 to 10 cm) needles borne in clusters of five. Young trees grow more slowly than associated ponderosa pine, but growth accelerates when they reach pole size, and then they sustain higher growth rates than their associates. Thus, sugar pine typically becomes the largest tree in the mountains of southern Oregon and California, except for the scattered groves of giant sequoia in the Sierra Nevada.

As sugar pines grow and mature, the lower branches are shaded out, die, and eventually fall away, leaving a long, clear trunk supporting a canopy high overhead. Development of clear boles was no doubt aided by the scorching and pruning effect of frequent, moderate-intensity surface fires that occurred in many stands prior to about 1900. Bark on mature trees is reddish brown to purple, irregularly fissured, and 2 to 4 inches (5 to 10 cm) thick.

Sugar pines often live 300 to 400 years or more. As they mature, some of the upper-crown branches commonly extend great distances horizontally, imparting a distinctive shape to mature sugar pines that a keen observer can identify from a mile or farther away. A few of the upper-crown branches in an old tree may reach out so far that they create an eccentric or even a bizarre shape.

Sugar pine cones are mostly 10 to 14 inches (25 to 35 cm) long, and some are longer yet. Before ripening, they are narrow, green, and heavy—2 to 4 pounds (1 to 2 kg). Thus, they fall like a missile when gnawed off by squirrels high overhead! Cones that mature on the tree dry out and turn brown, and their scales flex open, releasing large, winged seeds that average about 2100 per pound (4600 per kg)—nearly as big as pinyon pine nuts. Later, the open cones fall to the ground, where they remain intact for a few years unless gathered up by humans as decorations.

Sugar pine cone

ECOLOGICAL ROLE

Sugar pine usually grows scattered in mixed stands with other species ranging from shade-intolerant ponderosa pine to mid-tolerant coastal Douglas-fir and western white pine to shade-tolerant incense-cedar and true firs. (Shade-intolerant trees do not compete well in crowded forests.) Over the past century, the shade-tolerant competitors have proliferated in many of these forests due to the elimination of understory fires and to logging that removed sugar pines while leaving many of the competitors. The shade-tolerant species commonly form dense understories that increase stress on sugar pines and heighten their vulnerability to bark beetle attack. Historically, fires favored sugar pine because of its thicker bark and high, open canopy, which make it more fire resistant than some of its competitors, and the fact that fires create openings suitable for regeneration.

Like western white pine, sugar pine is vulnerable to white pine blister rust. The rust’s impact on sugar pine has so far been less severe than on western white and whitebark pines growing in more northerly latitudes where a damp climate seems more favorable to the disease. In sugar pine, rust-caused mortality is often most noticeable on saplings—the potential giant trees of the future. Loss of young sugar pines is exacerbated on much of the landscape by a diminished amount of disturbance that favors sugar pine regeneration.

In the past few decades, many of the older western white and sugar pines have been killed by a native bark beetle—the mountain pine beetle (Dendroctonus ponderosae). The larvae live in and tunnel through the soft inner bark layer (cambium), girdling the tree. Beetle outbreaks are enhanced by drought and overcrowded forest conditions that weaken the pines and make them more vulnerable. Employing silvicultural cutting treatments and prescribed fire to thin out competing trees—as a substitute for the historical role of fire—might help restore sugar pine as the monarch of the forest.

HUMAN HISTORY

Sugar pine provided two types of food eagerly sought by Native peoples (Moerman 1998). Several tribes harvested sugar pine seeds, which were eaten raw, roasted (and sometimes stored for winter use), boiled, pounded and mixed with cold water, dried, powdered, made into small cakes, eaten in a mush, or pulverized and made into a spread comparable to peanut butter. The sweet inner bark was gathered and eaten directly or mixed with other foods or dried into a powdered sugar. The pitch, also sweet at certain times, was chewed as gum. It oozes out of wounds on the trunk, becomes white, and tastes sweet, thus giving the tree its common name; however, on account of its laxative properties, it was eaten only in limited quantities. The taste is attributed to a sugar-alcohol called pinitol.

Sugar pine was first described in 1826 by botanical explorer David Douglas, a young Scot who was hosted by John McLoughlin, the Hudson’s Bay Company’s Chief Factor at Fort Vancouver, near present-day Vancouver, Washington. After seeing the large pine seeds and a gigantic cone brought in by Indians and trappers, Douglas became eager to locate the intriguing new species of pine that grew somewhere in the headwaters of the Willamette River (Douglas of the Forest by John Davies contains a detailed account). After five weeks of arduous travel southward through western Oregon in stormy fall weather, Douglas encountered an alarmed Indian. After establishing peaceful intentions, Douglas drew a sketch of the cone from the pine he was seeking out. The Indian pointed to the hills off to the south. Several hours later, Douglas reached the great pines, the largest of which had blown down. Douglas reported its circumference as equivalent to 18.4 feet (5.6 m) in diameter near the ground and 5.5 feet (1.7 m) in diameter at 134 feet (41 m). The tree’s total length was 215 feet (65 m). Today the largest known sugar pine is 11.7 feet (3.6 m) in diameter, at 4.5 feet (1.4 m) above the ground. It may be that the basal circumference figure attributed to Douglas was an error, but there is little doubt that the tree was gargantuan.

Douglas described the giant pines as having smooth trunks with branches only high above the ground, and these having cones hanging from their tips like small sugar-loaves in a grocer’s shop (Davies 1980). The cones were so high up that Douglas had to use his gun to clip them from the branches. The noise soon attracted eight Indians who were painted with red earth, well armed, and anything but friendly. Douglas tried to explain to them that he only wanted some cones, but they showed every inclination toward doing him harm. Finally he faced off against the entire group, cocking his gun and pulling a pistol from his belt. After several minutes of anxious confrontation, the Indian leader made a sign for tobacco, which Douglas indicated they would get only if they fetched him some cones. As soon as they left his sight, Douglas grabbed his three cones and some twigs and hastily retreated across the many miles to his camp. That evening he recorded his discomfort while lying in the grass, gun at his side and writing by the flicker of a piece of burning pitch-wood, constantly expecting to be attacked.

Because of the remoteness of most sugar pines in Oregon and the slow rate of settlement in their vicinity, nineteenth-century exploitation of the species was limited. Frank Lang, a forest ecologist and resident of Ashland, Oregon, has found numerous places where a large sugar pine had been felled long ago and milled into lumber right where it lay.

In contrast, the 1849 California gold rush brought throngs of European Americans to the doorstep of that state’s sugar pine country. Huge sugar pines were plundered on tens of thousands of acres of unprotected government land long before national forests and national parks were established. The magnificent trees with their prodigious volume of clear wood, similar to but larger than eastern and western white pines, made choice lumber; but they were often used wastefully. Much less sugar pine is harvested nowadays, and the sugar pines that are cut down are carefully processed into high-value lumber products, similarly to western white pine.

WHITEBARK PINE

Pinus albicaulis | Pine family (Pinaceae)

Whitebark pine is a sturdy, picturesque tree that accentuates the beauty and ecological diversity of high-mountain habitats. This slow-growing pine of the remote ridges and peaks was little known to most foresters and ecologists until the 1980s. By then, studies revealed that whitebark pine functions as a keystone species in the high-mountain ecosystem. Its pea-sized, nutlike seeds serve as a critical food source for wildlife, including grizzly bears. It also helps stabilize the snowpack and erodible soils on steep mountain slopes, thereby protecting the high quality of the water emanating from alpine watersheds in places where few if any other trees can grow.

Unfortunately, in much of its range, whitebark is now heavily damaged by epidemics of white pine blister rust and bark beetles and, due to fire suppression, it has little opportunity to regenerate. Recognizing the implications of this catastrophic decline, biologists and land managers have been trying out strategies to restore whitebark pine communities (Tomback and others 2001).

Whitebark pine

WHERE IT GROWS

Whitebark pine grows in the highest-elevation forest and at timberline along the entire Rocky Mountain chain from central British Columbia and Alberta southward through western Wyoming. In the coastal mountain ranges and the Cascades, whitebark pine is more narrowly confined to the timberline zone, where trees occur only in patches. Here, it extends from west-central British Columbia southward to the high Cascades and California’s Sierra Nevada. It also inhabits most of the high mountain ranges between the Cascades and the Rockies, including Oregon’s Blue Mountains. Whitebark pine does not grow among the high peaks on Vancouver Island, but small populations inhabit a few ridges in the dry, rain-shadow zone of the northeastern Olympic Mountains. This tree becomes more abundant eastward across the Northwest toward the Rocky Mountains. In the relatively dry mountains of southwestern Montana and east-central Idaho, whitebark pine makes up a major component of the subalpine forest.

Whitebark pine snag

APPEARANCE

Whitebark pine saplings often have a narrow, pyramidal crown, but they are slow growing and seldom develop the distinct annual whorls of branches that characterize faster-growing trees. Young trees have smooth, light gray bark, which gave rise to both the common and scientific names for this species. As they gradually mature, whitebark pines often develop a broad, irregular crown with multiple branches making up the trunk. Trees growing on good sites in moist subalpine forests often develop a straight trunk 80 feet (24 m) or taller resembling associated lodgepole pines. However, whitebark pines have five needles per cluster (versus two in lodgepole pines), and even their dead snags can often be distinguished by the large, upward-ascending branches at the top.

Whitebark pine branch tip with cones

At higher elevations, where the forest begins to break up into groves of trees and meadows, whitebark gains more living space and develops a stout, shorter trunk and a large, spreading crown. These trees provide plump blue grouse a place to roost and eat buds while protected from winter’s onslaughts and marauding goshawks. Ghost forests of great, spreading whitebark pines that died in a massive bark beetle epidemic in the 1930s still stand in many areas, a testimony to the durability of their resin-impregnated