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