This is a blog about the native conifers of the Pacific Northwest. It is a companion to the Northwest Conifers site. The blog will focus on timely and interesting details about our conifers, their connections to the rest of the environment, and our connection to them.

Tuesday, September 25, 2018

Andrews Experimental Forest

I had the great opportunity to visit the Andrews Experimental Forest east of Eugene, Oregon this summer. The HJ Andrews Experimental Forest is a 16,000-acre ecological research site, supported by Oregon State University and the US Forest Service.

The Andrews Forest was established in 1948. In the 1950’s, the research focused on increasing the “efficiency of forest operations.” At that time, forestry was viewed as a form of farming. Just as the corn farmer grows crop after crop of corn, the forester grows crop after crop of trees. The question was: How do we use science to maximize the tree harvest? Of course, natural forests in the Pacific Northwest didn’t grow as crops. The trees here grew to be large and old. But what about these old-growth forests? They were considered very inefficient, in fact worse than inefficient, producing no new logs. First they needed to be cut down. Then efficient tree farming could begin. The process was:  Plant new trees, usually Douglas fir, grow them for 60 years, harvest them by clear cutting, repeat. This was the new “scientific” approach to forestry, which at least replaced the devastating cut and run forestry that removed forests all across the country, starting at the East Coast. Still, this new approach to forestry was focused on maximizing timber production.

Lookout Creek in the Andrews Forest
However, the researchers at the Andrews Forest also began to study the workings of a naturally growing forest. It is as if they had just discovered something that Henry David Thoreau had written 100 years earlier: “Would it not be well to consult with Nature in the Outset? For she is the most extensive and experienced planter of us all” (from “The Succession of Forest Trees.”) It is this focus on how a natural forest grows and how the various organisms interact, grow, and change over time that has occupied the scientists at the Andrews Forest. This new research has led to some amazing discoveries and a new understanding of how to manage a forest ecosystem.

Ancient Douglas firs in the Andrews Forest
Jon Luoma’s wonderful book, The Hidden Forest, tells the story of the research at the Andrews Forest. Some of the most interesting research reveals how different species in the forest work together for mutual benefit, an arrangement called symbiosis. Here are some fascinating examples.

All plants need nitrogen to thrive. A young forest gets nitrogen from nitrogen fixing shrubs. Red alder trees, which often are the first trees to grow in a new forest also have nitrogen fixing bacteria in their roots. However, as a forest matures, conifers grow to shade out the shrubs and even the alders. By the time the forest becomes mature, all these nitrogen fixers are gone. So, where does a mature forest get the nitrogen it needs? This mystified scientists for a long time. They didn’t find the answer until a team at the Andrews Forest used ropes to climb into the top of a Douglas fir tree. What they found 200 feet above the ground was an abundance of lichen growing on the branches. The lichen they found is lettuce lichen (Lobaria oregana). Testing showed that this lichen was full of nitrogen. Much of the lichen eventually falls to the forest floor allowing the nitrogen to enrich the soil. Without the lichen, an old-growth forest probably could not exist. In return, the lichen doesn’t ask for much, just a place to live up in the abundant sunlight of the forest canopy.

Lichens themselves are an interesting study in symbiosis. A lichen is not a single organism. It is a composite organism made of algae and fungi living in a symbiotic relationship. The algae perform photosynthesis and supply energy to the lichen. Threads of fungi provide structure keeping it all together, gather water and nutrients, and attach to the tree where the lichen grows.

Another fascinating discovery was finding fungi living inside apparently healthy conifer needles. Why didn’t the fungi harm the needles, and just what were the fungi doing there? Well, trees have a problem with defoliating insects. Unlike short-lived plants, trees live too long to react to evolving short-lived insects. It turns out that these fungi have a symbiotic relationship with the needles. In exchange for the energy supplied by the needles, the fungi protect the needles by creating compounds that poison the defoliators. If the defoliators develop a resistance to the poison, the short-lived fungi can quickly change to create new, effective poisons. It’s a constant evolutionary race, not unlike the race between new strains of disease and the pharmaceutical companies that must create new forms of antibiotics, although the fungi don’t make billions of dollars for their services.

Over 100 years ago, scientists discovered another symbiotic relationship 200 feet below in the root systems of the trees. While researching how to grow truffles, a scientist discovered that threadlike tendrils attached to the truffles were connected to the roots of trees and other plants. These are the fungi that produce the truffles. He also discovered that seedlings with these fungal connections grew much faster. Now we know that these fungi get nourishment from the tree. In return, the fungi collect water and minerals that feed the root system of the tree.

Douglas squirrel munching on a fungus
In the 1970’s scientists at the Andrews Forest discovered more remarkable connections in the ecology of the forest, not just between the fungi and trees, but also between the fungi and small mammals. Voles, chipmunks, squirrels, and mice, love truffles and other fungi. For some, it is an important part of their diet. It’s no surprise that squirrel poop is chocked full of the reproductive spores from the fungi, which, of course, these small mammals distribute all over the forest making their own little contributions to the forest ecosystem. In their turn, the trees provide habitat for the mammals both when the trees are alive and especially when they’re rotting on the ground. Voles, for example, depend on these rotting logs. The rotting logs, then, become an essential part of the forest ecosystem, not just providing living quarters for the voles, but food for insects and other organisms as well. Eventually, nutrients in the log are recycled back into the soil. These factors have led researchers at the Andrews Forest to re-assess the old forest practices of clear-cutting and removing the dead material from the forest floor.

These and other discoveries at the Andrews Forest led to a new approach to forest management based on their studies of naturally growing forests. If Thoreau were alive today, he would say, “Well, it only took you 100 years to figure that out.”
Andrews rain gauge with baffles to increase accuracy 
My rain gauge
The two-day workshop I attended at the Andrews Forest was hosted by the Oregon Season Tracker Program, a joint project of the OSU Extension program and the Andrews Forest. The Oregon Season Tracker Program enlists volunteer citizen scientists to collect and record precipitation and plant phenology data. Daily precipitation is easy to record using a standard rain gauge like the one above. We report the precipitation to the CoCoRaHS Web site.

Plant phenology observations enable us to track the changes in plants as they respond to seasonal changes and variations in weather and, in particular, climate change. We report our phenology observations on the Nature's Notebook site.

 More Andrews Forest photos
Stream monitoring station

Western hemlocks

Temperature monitor

Experimental rain gauges


More info

Sunday, August 26, 2018

Focus on Spruce

Sitka spruce at the
Cape Perpetua

About 30 species of spruce grow across the northern hemisphere, most notably in the cold arctic regions. Fossils of spruce date to 65 million years ago. The spruces are most closely related to the pines, but you would never guess this from looking at any spruce. Judging from the needles and cones, you would think that they’re not even in the same family. Three species of spruce are native to the Pacific Northwest: Sitka spruce, Engelmann spruce, and Brewer spruce. The most ancient species were two of our natives: Brewer spruce and Sitka spruce. Also, spruces originated in the Northwest. Millions of years before humans discovered the Bering Land Bridge, spruces made a slow migration across to reach Asia and Europe. It may seem odd to think of trees migrating. They generally stay rooted in one spot. Yet even though the trees themselves don’t travel, their winged seeds do. So each generation can sprout a few hundred feet beyond the previous generation. It’s easy to see that trees would be able to migrate thousands of miles in millions of years.

Spruces can grow to 200 feet tall, given a chance. Sitka spruce is the largest species of spruce. The largest Sitka spruce in Oregon is located at Cape Meres. The largest Sitka spruces in the world are in Washington state, the Lake Quinault Spruce, growing on the south shore of Lake Quinault, and the Queets Spruce, growing near the Queets River in Olympic National Park.
Spruce needles and cones

Twig with pegs where needles attached
The Spruces are easy to identify. They have some distinguished and distinguishing features. First, consider the needles: They look like Douglas fir needles, radiating all around the twig, but they are pointed and sharp. Unlike Douglas fir and the true firs, each spruce needle grows on a small peg. In fact, these pegs are unique in the pine family, and remain even after a twig loses its needles. The cones have thin scales, with their bracts hidden safely inside on mature cones, again unlike Douglas fir, which has conspicuous three-pointed bracts poking out from each scale. The bark is gray and usually breaks into scales on large trees.

Spruce gall
Spruce trees often develop galls. People often confuse these galls with cones, especially when there are no cones present on the tree. These galls are caused by the gall adelgid, a tiny insect that loves to eat the tender spruce needles after they burst from buds in the spring. The tree reacts by producing a gall on the twig tip.

The scientific name for spruce is Picea, which is derived from the Latin for "pitch."

Spruces dominate vast northern regions of the northern hemisphere including Alaska, Canada, and Russia. The only other conifers that grow this far north are the larches. Farther south in North America and Asia, spruces are confined to higher elevations in the mountains, extending into Mexico in North America and to the Himalayas in Asia. Sitka spruce is one exception to this attraction to cold extremes. It clings to the Pacific Coast from California to Alaska, thriving where other trees avoid windswept shorelines continuously peppered with salty ocean spray.

Engelmann spruce bark
Spruce wood is used for construction and making paper. The original Christmas tree was a Norway spruce. The most celebrated use of spruce is in the making of fine string instruments. It’s also used for piano sound boards. You might think of Howard Hughes’ famous Spruce Goose airplane as another use of spruce wood. The huge airplane was made of wood, but the wood used in the Spruce Goose was birch. No wonder Howard Hughes never liked that name. It’s also been called the Flying Lumberyard, but I doubt that he would have liked that any better. The Spruce Goose is now on display at the Evergreen Aviation & Space Museum in McMinnville, Oregon.

Conifers of the World, James Eckenwalder

Friday, July 20, 2018

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.


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).


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


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

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

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