Focus on Ponderosa Pine

Ponderosa pine may not be the tallest tree in the Pacific Northwest, but it is arguably the most picturesque and stately, owing to its colorful, puzzle piece bark and habit of growing in grassy, open parklands where each tree stands out as an individual. It is the second most distributed pine in western North America after lodgepole pine. But ponderosa pine is the iconic tree of the western United States, featured in nearly every western movie and more than a few television series, including Bonanza, set at a ranch called The Ponderosa.  The scientific species name of ponderosa pine, Pinus ponderosa, is easy to remember, because it matches the common name. 

Ponderosa pine is a large tree, growing to 200 feet (60 meters). It is most easily recognized by its distinctive bark, with its long, flat, orange or yellow plates separated by dark furrows. The flaking surface of the plates looks like the pieces of a jigsaw puzzle. The bark is more colorful on older trees, most notably on large trees growing east of the Cascades. The needles are no less distinctive. They are longer than any other pine native to the Northwest, up to 12 inches long. And ponderosa pine is the only pine in the Pacific Northwest outside of southwest Oregon that has 3 needles per bundle. Jeffrey pine and knobcone pine are native to southwest Oregon and have 3 needles per bundle. Jeffrey pine is similar to ponderosa pine, but the Jeffrey cones are twice the size of ponderosa cones. Knobcone pine needles are much shorter, and the small cones remain closed on the tree. 

The ponderosa cones are egg-shaped when open and 3 to 6 inches long with a sharp prickle on each scale. If you pick up one of the cones, you may feel just how prickly they are. When mature, ponderosa cones open, disperse their seeds, and soon fall to the ground, where hapless hikers pick them up and quickly drop them again.

Where it grows 

Ponderosa pine is common throughout much of the western US. It is the most common conifer in the Northwest east of the Cascades, growing at elevations up to 5000 feet (1500 meters). Although it thrives in dry, mountainous regions, it is surprisingly native to the wet habitat of the Willamette Valley. Even more surprising, these natives are better adapted to wet areas than the Douglas firs that grow in the valley. Most of the ponderosa pines growing in the Willamette Valley probably came from seeds grown east of the Cascades, but there are a few locations where you can find some trees that are native to the Willamette Valley, for example, at the Tualatin Hills Nature Park. Cooper Mountain Nature Park and the Tualatin River Wildlife Refuge have plantings of young Willamette Valley natives.

Subspecies

Two subspecies grow in the Pacific Northwest:* 

• Subspecies ponderosa grows east of the Cascade crest and throughout the mountains of eastern Oregon and Washington. It also grows in the mountains of Idaho. 
• Subspecies benthamiana grows in the Willamette Valley, a few locations in western Washington, and the coastal mountains of southwest Oregon. It also grows in the mountains of California, especially the Sierra Nevada. 
• If you travel farther east, you will encounter subspecies scopulorum, which grows throughout much of the Rocky Mountains. Ponderosa pine is the state tree of Montana.

Subspecies ponderosa, benthamiana, scopulorum**

It is difficult to identify these subspecies based on the characteristics of the trees. The needles of subspecies benthamiana are often longer those of the other subspecies, up to 12 inches long (30 cm). The needles of subspecies ponderosa are up to 10 inches long (25 cm). The needles of subspecies scopulorum are even shorter, no longer than 7 inches (17 cm).

Fire

Many conifer species have a special relationship with fire. Ponderosa pine has an unusually friendly relationship with fire. Did you ever wonder why you see open ponderosa forests with just grasses and small forbs growing under the trees? Why are there no limbs on the ground or other conifers growing in the understory like you would see in a Douglas fir forest? The answer is frequent fires. These open woods depend on frequent fires. The thick bark on the ponderosa pines isn’t harmed by these fires. Other plants adapted to these fires can regenerate after the fires. But the fires prevent competing conifers like grand fir from growing. The small firs and any shrubs are burned in the fire along with any other combustible debris left on the ground. Unfortunately, in the past century these fires had been aggressively suppressed throughout the west. This has allowed the ponderosa forests to become crowded with combustible fuels in the understory. When there is a fire, it becomes a hot wildfire that leaps to the canopy, killing the ponderosa pines. It also burns hotter on the ground, killing other plants that normally survive the frequent, low-intensity fires. 

Recently, forest managers have attempted to restore the fire regime in these forests, by allowing fires to burn when possible, and by setting smaller, controlled fires. The controlled fires remove the excess fuel from the forest, allow the forest to recover, and help prevent hot-burning wildfires. People often object to the smoke caused by controlled fires, but wildfires produce about 10 times the amount of smoke per acre compared to controlled fires. These fires can be set at times when weather conditions are conducive to good smoke dispersal and when the winds blow the smoke away from populated areas.

Pollen cones

Uses

Ponderosa pine lumber is widely used in home construction, window and door frames, moldings, and furniture. It is often sold as yellow pine. Squirrels, chipmunks and many kinds of birds eat the seeds. Some cache the seeds, which facilitates the propagation of the pines. Clark’s nutcrackers are usually associated with whitebark pine, but they will settle for ponderosa pine seeds, often transporting them great distances and storing them in caches in the ground. The seeds they don’t eat give the ponderosas a chance to start a ponderosa forest in a new location.

Lewis and Clark encountered this pine in 1805 and were impressed by its long needles. They also made canoes from ponderosa pine and floated them down the Columbia River. In 1826, David Douglas found ponderosa pines growing near Spokane and named them for their heavy (ponderous) wood. Other common names include yellow pine, western yellow pine, and blackjack pine.

John Muir on ponderosa pine

I have often feasted on the beauty of these noble trees when they were towering in all their winter grandeur, laden with snow--one mass of bloom; in summer, too, when the brown, staminate clusters hang thick among the shimmering needles, and the big purple burrs are ripening in the mellow light; but it is during cloudless wind-storms that these colossal pines are most impressively beautiful. Then they bow like willows, their leaves streaming forward all in one direction, and, when the sun shines upon them at the required angle, entire groves glow as if every leaf were burnished silver. -- John Muir, Yosemite, Ch. 6

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*The Gymnosperm Database lists these as subspecies. Oregon Flora Project lists them as varieties.

**USGS distribution map. Subspecies distribution based on information from conifers.org

Focus on Lodgepole Pine

Lodgepole pine has adapted to several very different habitats in the Pacific Northwest. It grows along the Pacific Coast, where it is often called “shore pine.” But it also grows in the mountains, occasionally right up to the timber line. This split in its range may be explained by the fact that it does not compete well with most other conifers. So it is often limited to locations where other conifers cannot grow, in one case along the coast where the trees are buffeted by wind and salt spray, and in the other, sites with poor soils or frequent severe fires. The conditions where it grows also explain its different growth forms. Growing in dense stands subject to frequent fires, it grows straight and tall to a height of 160 feet (50 meters), in character with its “lodgepole” namesake. Along the coast and on windy mountain ridges, it is usually much shorter and rarely straight. It is short and bent, even shrub-like in form, in character with its scientific name, Pinus contorta.






Recognizing lodgepole pine

• Needles: Lodgepole pine is easy to identify, because it is the only pine native to the Northwest with 2 needles per bundle.
• Cones: The egg-shaped cones are 2 inches long and have sharp prickles on the scales.
• Bark: The bark is dark gray and scaly with small furrows.

Fire

Lodgepole pine is often characterized as a fire-dependent species, because the mature cones remain closed until heated by a fire, a feature called serotiny. After a fire, the serotinous cones open and disperse their seeds, generating a new stand of pines. This is what happened in 1988 when spectacular fires burned large stands of lodgepole pine in Yellowstone National Park. In the years after the fires many of the burned areas were alive with new seedlings, the beginnings of a new lodgepole pine forest.

However, this feature of the cones is variable. It varies between the different varieties described below and varies as the tree ages with older trees producing more serotinous cones. It also varies based on the local fire history. Trees growing in areas where there are frequent fires are more likely to produce serotinous cones. This is no surprise. It’s just another example of the adaptability of lodgepole pine. Serotiny is even variable among the cones growing on one tree, enabling its offspring to adapt to changing conditions. Evolution rules! And lodgepole pine is perhaps its most ardent agent of change among the conifers.


Varieties

As lodgepole pine has adapted to different environments, many of its features have changed, especially the cones. Writers* generally identify three varieties:

• Shore pine (var. contorta) grows all along the Coast from California to Southeast Alaska. The cones are curved, and they usually open and disperse their seeds when mature. The needles are shorter (less than 2 inches – 6 cm) and thinner than the other varieties (with needles up to 3 inches – 8 cm). After seed dispersal, the cones may remain on the tree for some time.
• Sierra-Cascade lodgepole pine (var. murrayana) grows in the Cascades of Oregon. It also grows in the Sierra Mountains of California. Its cones are nearly symmetrical, and they nearly always open and disperse their seeds as soon as they mature, dropping the cones soon after.
• Rocky Mountain lodgepole pine (var. latifolia) grows in the Cascades of Washington and the mountains in the northeast corners of Oregon and Washington. It also grows throughout much of the Rocky Mountains. The cones are curved and variably serotinous, often remaining closed until heated by a fire. The non-serotinous cones can remain on the tree for some time after dispersing its seeds.

Note that the borders between the varieties are not necessarily recognized by the trees. Try as we will to classify all of nature into tidy little boxes with clearly drawn lines, nature doesn’t usually color inside the lines. Lodgepole pines are no exception. They interbreed at the borders between the varieties and adapt to local conditions.  

Shore Pine at Oceanside, Oregon

Uses

Native Americans used this pine for teepee poles (lodge poles) wherever the trees were available in the western U.S. Some traveled great distances to find suitable poles in the mountains where they grew. Today lodgepole pine is used to make paper, paneling, plywood and fiberboard, and to build barns and other post-and-beam structures.

Chief Joseph pine in the Winter
Garden at Hoyt Arboretum 

Chief Joseph Pine

The Chief Joseph pine is a dwarf variety of lodgepole pine that surprisingly turns golden-yellow in the winter. Doug Will of Sandy, Oregon discovered this amazing golden tree growing in the Wallowa Mountains and named it for the famous leader of the Nez Perce tribe. It looks like a normal lodgepole pine in spring and summer. But in late fall, the needles turn to a bright golden color. You might expect it to shed its needles like a larch, but they remain on the tree all winter and then turn green again in the spring. Its striking color and extraordinary growth habit have made it a popular item at nurseries across the country.

You can see a Chief Joseph pine in its winter color here.






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*Chris Earle (www.conifers.org), Aljos Farjon, A Handbook of the World’s Conifers, James Eckenwalder, Conifers of the World, Zsolt Debreczy and Istvan Racz, Conifers Around the World. Common names from Eckenwalder and the USFS Silvics Manual