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.

Sunday, November 15, 2015

Fall Conifer Colors

Western Larch
I love seeing the golden colors of conifers in the fall. But aren’t conifers evergreens? Most conifers are evergreen, but a few species go for the gold in the fall. Like most broad-leaf trees, they are deciduous. That is, they drop their leaves every winter. This adaptation helps the trees survive the freezing cold of winter. On the other hand, most conifers have adapted to the cold by adopting strategies that enable the needles to survive freezing cold.

Since most conifers are evergreen, you don’t expect to see conifers turning golden-yellow in the fall. That is a big part of the charm of deciduous conifers. Mixed in with the evergreens, a burst of flaming gold is an unexpected exception. The color is more striking when it is surrounded by a sea of green.

Most deciduous conifers are larches. Western larch (scientific name, Larix occidentalis) is the only deciduous conifer species native to Oregon. You can see it growing in the Cascades.  It also grows in the mountains of northeastern Oregon and Washington, northern Idaho, and western Montana. Even though Washington is called the Evergreen State, the alpine larch (Larix lyalii) puts on a dazzling display of golden color each fall in the high elevations of the North Cascades.

Japanese Larch at Hoyt Arboretum
Metasequoia
If you want to see a great display of golden conifers without driving to the mountains, check out the conifer collection at Hoyt Arboretum in Portland. The most striking are the Japanese Larch (Larix kaempferi) at the south end of the Redwood Trail. Another deciduous conifer is the dawn redwood (Metasequoia glyptostroboides), located at the north end of Bray Lane. It's commonly called by its genus name, Metasequoia, likely because it is the only species in the genus. Also, no one can say Metasequoia glyptostroboides without taking a breath before the end. Ancient fossils indicate that Metasequoia were once common in Oregon and much of North America and Europe. Living specimens are native to China.
Bald Cypress

There are two more deciduous conifers native to North America. One is the eastern larch or tamarack (Larix laricina), which grows from New England, across Canada, and in Alaska. The other is the bald cypress (Taxodium distichum), which grows in the swamps of the southeastern United States. You can see a bald cypress at Hoyt Arboretum just south of the Metasequoia on Bray Lane.








Ginkgo
Another unexpected deciduous tree is the maidenhair tree, commonly called by its genus name Ginkgo (species name (Ginkgo biloba). The Ginkgo is native to China and is an ancient close relative of the conifers. Its leaves turn bright yellow in the fall. You can see one next to the Visitor Center at Hoyt Arboretum and several growing at the north end of the Bristlecone Pine Trail.

When you are looking for fall colors, be sure to check out the deciduous conifers at Hoyt Arboretum.

Thursday, July 30, 2015

Focus on Pacific Yew

Pacific yew (Taxus brevifolia) is our native yew. Of all the conifers native to the Pacific Northwest, Pacific yew is a rare gem. Although lumbermen and loggers once maligned it as a saw-dulling trash wood, and botanists questioned its place in the community of conifers, it has played an important role in ancient and recent human history. It also has a distinctive place in the forest community and presents a unique opportunity for the alert hiker trying to take in the diversity of the forest.

Grand fir, Pacific yew, and western hemlock
How to identify Pacific yew: Look for a small tree growing in the understory in the shade of larger Douglas fir of western hemlock. The needles are short, flat, and spread out on opposite sides of the twig in flattened rows like a grand fir or western hemlock. Like these trees, Pacific yew needles are dark green on top, but instead of showing bright white lines on the lower surface, they are just a lighter green below. The white lines or bands of stomatal bloom on the lower surface are often indistinct or not visible, but close inspection with a hand lens reveals several rows of stomata in each band.  The needles are about 1 inch long, shorter than grand fir needles, but generally longer than those of western hemlock.

The most unusual feature of the yew genus is the structure of the cones. From all appearances, you might think that yews produce bright red berries instead of cones, a feature that has cast doubt on their status as a conifer. However, the berry-like fruit is a modified cone scale that develops into a small fleshy aril. Each aril partly encloses a single seed. Birds eat the arils and disperse the seeds. These seeds are quite poisonous to humans but pass through the bird’s digestive system with no apparent harm to bird or seed. Looking for the arils is not a dependable way to identify Pacific yew. The arils only appear in late summer. Also, pollen cones and arils do not usually grow on the same tree. Only the female trees produce arils, and then only if they are fortunate enough to be pollinated by a nearby male tree.

The bark of Pacific yew is also quite distinctive and, as it turns out, important. When not completely covered in moss, you can recognize Pacific yew by its bark, which is a patchwork of peeling papery brown or gray scales over a smooth inner layer that is purple or red-brown. On larger trees, the trunk becomes fluted.

The bark of Pacific yew was nearly its undoing. Scientists discovered a drug called Taxol in the bark, which proved to be an effective treatment for various cancers. The problem was that it required large amounts of yew bark to render a small amount of Taxol. Also, since the yews are not common, the supply of yew bark was quite limited. It became apparent very quickly that harvesting large amounts of Pacific yew bark was not sustainable. Fortunately for the Pacific yew, scientists soon discovered a way to synthesize Taxol from the needles of the English yew (Taxus baccata). This yew is a common cultivated shrub and easily regrows after trimming, making it ideal for hedges and topiaries. The clippings from yew hedges and other plantings provide a steady supply of yew material that can be used to manufacture Taxol. Even though Pacific yew is no longer used as a source for Taxol, it was key to the discovery of the drug.

Other uses: The wood of Pacific yew is exceptionally hard and strong. The first people to live in the Northwest used it for tools, canoe paddles and weapons, especially bows. They even used wedges made of yew to split cedar. The needles and bark of the yew also had various medicinal uses. Pacific yew has little commercial use today, but it is still used to make bows.

Where it grows: Pacific yew grows in moist, shady areas throughout the Northwest at elevations up to 5000 feet. It is not common, and when you find one, there may be no others growing nearby. It is usually under 35 feet high, growing in the shade of larger conifers, but can grow to 50 feet. It grows slowly, so a 35-foot tree may be over 100 years old. East of the Cascades, it often grows as a low shrub. Although it is not a common conifer, its rarity only enhances its appeal. If you are attentive when hiking the forests of the Northwest, you will find one growing here and there.

Names: Taxus is Latin for yew. Brevifolia is Latin for "short leaved," so named because its needles are shorter than those of English yew. Other common names: California yew, western yew, and mountain mahogany.

At one time all yews were considered to be subspecies of English yew. Now they are commonly classified as about seven different species. Besides English yew, which is native to Europe and sometimes called European yew, there are four species native to North America, and two native to Asia: Canada yew, Florida yew, Mexican yew, Pacific yew, Japanese yew, and Chinese yew.

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See also

Taxus brevifolia in The Gymnosperm Database

Pacific Yew in Silvics of North America

Wikipedia entry for Pacific Yew

The Story of Taxol

Yew cuttings help cancer research


Wednesday, July 15, 2015

Stomatal Bloom



What is stomatal bloom?  And why do we care about it anyway?

Bloom on grand fir and western hemlock
The first question is easy. Stomatal bloom is a waxy white coating around stomata.  OK, but what are stomata? They are the tiny pores on conifer needles that enable them to breathe. That is, the stomata are openings used to exchange gases, taking in carbon dioxide and exhaling, as it were, oxygen and water vapor. Each stoma (pl. stomata) has two guard cells that control the size of the opening, like tiny lips. When it rains, the lips close to keep the water out of the internal part of the leaf. And the bloom? It aids in water proofing the needles, both keeping out rain water and helping to retain water when it is dry.

Rows of stomatal bloom on grand fir
When you view the underside of the needles of a grand fir or western hemlock, you can clearly see two white lines of bloom on each needle. Each line or band of stomatal bloom contains several rows of stomata. You can see these individual rows with a good hand lens.

Pacific yew
Now, why do we care about all this?  We can use the differences in the presence of stomatal bloom to help identify our native conifers. For example, you can distinguish Pacific yew from other native conifers by looking at the lower surface of the needles. The needles on grand fir and western hemlock have two bands of stomatal bloom on the lower surface, but the yew has no distinct bands of bloom. The lower surfaces of yew needles just appear to be a lighter shade of green.  That’s not to say that there is no stomatal bloom on Pacific yew  needles. It’s just that the color is muted compared to the striking white color found on grand fir and western hemlock.

Pacific silver fir and subalpine fir
It is often difficult to distinguish firs found near the timberline in the Cascades. Pacific silver fir and subalpine fir look similar. Both have stomatal bloom on the lower surface of their needles. However, if you look carefully at the needles of subalpine fir, you will see that they also have bloom on the upper surface. On the other hand, the upper surfaces of silver fir needles are dark green.


You can distinguish western white pine from sugar pine by looking at the stomatal bloom on their three-sided needles. Sugar pine has bloom on all three sides, while western white pine has bloom on just two.

Western red cedar and Port Orford cedar
Stomatal bloom sometimes appears in different patterns. The bloom on the lower surface of western red cedar leaves resembles the shape of a butterfly, while the bloom on Port Orford cedar leaves forms an x-shaped pattern.

Shade-tolerant conifers in the Pacific Northwest usually have bloom only on the lower surfaces of the needles. This is particularly noticeable in the firs and hemlocks. Natives with bloom on the lower and upper surfaces are generally more intolerant of shade, and often grow in the higher elevations. This seems reasonable. The bloom on the upper surfaces would block the sun. Shade-tolerant trees need to have clear upper surfaces to capture what sunlight they can under the forest canopy. On the other hand, the bloom on the upper surface of needles gives trees growing in direct sunlight protection from the sun’s ultra-violet rays, especially in higher elevations where sunlight is more intense. This may explain why you find subalpine firs growing in open meadows near the timberline, while Pacific silver firs compete better in shady woods.

These relationships between stomatal bloom and the distribution of conifers are bound to be complex. In any case, some familiarity of the differences in the presence of stomatal bloom on conifer needles can help us identify conifer species in the wild.
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See also

THE RELATIONSHIP OF CUTICLE STRUCTURE TO THE VISIBLE AND ULTRAVIOLET SPECTRAL PROPERTIES OF NEEDLES FROM FOUR CONIFEROUS SPECIES by JOHN B. CLARK AND GEOFFREY R. LISTER in Plant Physiol. Vol. 55, 1975, p. 307

Air Pollutants and the Leaf Cuticle edited by Kevin E. Percy, John Cape, Richard Jagels, Caroline J. Simpson, p. 90.


Subalpine Fir in Silvics of North America


Tuesday, June 23, 2015

Focus on Grand Fir

Grand fir is the only true fir found in the lower elevations of the Pacific Northwest, so it’s no surprise that it’s sometimes called “lowland fir.” David Douglas was more impressed when he found large specimens growing near the Columbia River on one of his journeys to the Northwest and named it grand fir, Abies grandis. It deserves this grander name. It can grow to 200 feet tall.

Needles: Grand fir is easy to identify just by looking at its needles. They spread out on opposite sides of the twig in flattened rows, unlike any other conifer in the Northwest. 
However, you may notice that when growing in direct sunlight the needles sometimes crowd to the top of the twig. Each twig typically has a mixture of long and short needles, the longer ones being about 1.5 inches. The individual needles are flat with a groove along the top. Their color is a dark, shiny green on top with two white lines underneath. Pacific silver fir, which grows at mid to higher elevations of the Cascades has similar needles but they point forward and upward rather than lying flat like grand fir. However, if you find a twig blown out of the top of a grand fir, it can look very much like it came from a Pacific silver fir.

Note the non-flat needles
Cones: You can hike the forests of the Northwest for years and never see a grand fir cone. They sit upright on the branches near the treetop and are difficult for ground-dwelling humans to see. Like other firs, grand fir cones fall apart at maturity, dispersing the winged seeds and leaving a cone core spike on the branch. You won't find grand fir cones on the ground unless they were dropped by a squirrel, which happens more often than you might think.

Bark: The gray bark is smooth with blisters on small branches, breaking into flat ridges and narrow furrows on large trees. It is easily distinguished from the deeply furrowed bark of Douglas fir or the stringy western red cedar bark, but looks similar to the bark of western hemlock.


Grand fir grows at lower elevations throughout most of western Oregon and Washington, but it also grows at elevations up to 5000 feet. It is the only true fir you will find growing below 1500 feet. (Remember, Douglas fir is not a true fir.) Grand fir is a moderately shade-tolerant tree that thrives in moist areas. It is not as abundant as Western Hemlock in its range, but you can usually find it growing here and there among the other conifers, often under larger Douglas fir. Grand fir is more common in the mountains of northern Idaho, occasionally growing in pure stands.

The grand firs that grow east of the summit of the Cascades are sometimes characterized as a separate variety. These eastern trees grow significantly slower than the west slope trees.

Like other true firs, grand fir is used to make plywood and paper. It is also one of the species of lumber sold as “Hem-Fir,” indicating that it is either hemlock or fir. It is not as strong as Douglas fir lumber, but is used in home construction for framing. The white, soft wood is easy to work with and does not split when nailed, which makes it an ideal choice for baseboards and other mouldings. Christmas tree lots often feature grand fir. Its dark-green needles and its strong fir-like fragrance make it a popular choice. If you are allergic to the strong fragrance, you might consider it for outside planting, and choose a similar-looking Nordmann fir for a Christmas tree.

The biggest grand firs grow in western Washington. The largest by volume is in Olympic National Park.  The tallest is 267 feet in height. It’s located in the Glacier Peak Wilderness in the North Cascades.

Looking for grand fir in the Cascades near Crater Lake and the coastal mountains of southwest Oregon can be tricky. Grand fir in these areas hybridizes with white fir (Abies concolor). The characteristics of the hybrids can vary between these two species.
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See also



Monday, June 15, 2015

Focus on Western Red Cedar

If you are a fan of ferns, you will love western red cedar (Scientific name: Thuja plicata). This conifer looks like a fern on steroids. It is big, even for a tree, sometimes growing to 200 feet. But its foliage of scale-like leaves spreads out in delicate, fern-like sprays. It is easily recognizable in the lower elevations of northwest Oregon and western Washington because it is the only conifer with scale-like leaves. In the Cascades where other cedars grow, you can distinguish western red cedar by the shape of the leaves, which are about as wide as they are long, and by looking at the lower surface of the leaves, which often have a white butterfly-shaped pattern.


The 1/2-inch cones are smaller than western hemlock cones. They sit on top of the branches, often in great numbers. Each cone looks like a tiny rose bud. You can easily recognize a western red cedar even when the branches are too high to see either leaf or cone. Just look for a tree trunk with thin, stringy strips of brown bark. The base is usually buttressed to a greater degree than other conifers.


Western red cedar thrives in wet areas near streams, but don’t be surprised if you find it growing on hillsides and even ridgetops in the coastal forests, where rainfall can top 80 inches in a year. In the Cascades, it often grows to an elevation of 5000 feet. In some locations, it grows higher, for example, around the rim of Crater Lake.


The delicate beauty of western red cedar is well-known. It adorns the cool woods where hikers walk and is a popular and attractive choice in landscaping in its native form. A number of cultivars are available from nurseries, many with patches of yellow foliage.   



Building our sunroom
The wood of western red cedar is light and soft. It has a pungent, pleasing smell and an attractive red-brown color. Its resistance to rotting makes it the wood of choice for many uses, including shingles, siding, decking, and fencing. The most remarkable and extensive uses of western red cedar were before European settlers arrived in the Pacific Northwest. For thousands of years, it was the most important tree to the people who lived in the region, playing an important part in nearly every aspect of life. It was widely used in making canoes, totem poles, tools, and utensils. Without the benefit of saws, they were able to drive wedges into standing trees and split off boards that they used to build lodges. They stripped the bark and used it to make rope, baskets, mats, fishing nets, and even clothing.


Names: The genus name, Thuja, is derived from the Greek name for a kind of juniper. Plicata means "pleated," referring to the pattern of its leaves. Note that the genus of western red cedar is not Cedrus, the genus of the true cedars from the Middle East and Himalayas. The Indian name for the tree, "Shabalup," means "dry underneath," a good thing to remember if you’re ever caught in a rain storm out in the woods. Other common names are canoe cedar, Pacific red cedar, British Columbia cedar, and shinglewood. It is also called giant arborvitae (Latin for "tree of life"), in reference to its East Coast cousin, arborvitae (Thuja occidentalis), a much smaller tree. Arborvitae is a widely planted ornamental and commonly used to create hedges. It is also called eastern white cedar, although curiously, occidentalis means western. From the standpoint of Carl Linnaeus, the Swedish botanist who named it in 1753, it was very western.


Quinault Lake Cedar
Giant Cedars: The biggest western red cedar in the Northwest is the Quinault Lake Cedar on the north shore of Lake Quinault in western Washington. It is 174 feet tall and 19.5 feet in diameter. It has been characterized as the largest cedar in the world measured by volume. Recently discovered and measured in 2011, the largest western red cedar in Oregon is the Arcadia Cedar, near Arcadia Beach State Park, south of Cannon Beach. It is 17 feet in diameter and about 152 feet tall. Not only is it the biggest western red cedar in the state, but the team from Ascending the Giants who measured it determined that it is the biggest tree in the state, based on a scoring system that uses circumference, height and crown spread. A short trail leads to the Quinault Lake Cedar, but there is no trail to the Arcadia Cedar.
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References and More Info:
http://www.conifers.org/cu/Thuja_plicata.php
http://www.olympicpeninsula.org/things-to-do/worlds-largest-red-cedar-tree
http://www.tillamookheadlightherald.com/news/oregon-s-giant-tree/article_84e3da8c-e8d1-11e2-8c69-0019bb2963f4.html
http://ascendingthegiants.com/

Monday, June 1, 2015

New World Cedars


Port Orford cedar
As is often the case with common names for trees and other living things, the names do not reflect their scientific classification. The common names often reflect other concerns. Life isn't all just science and academic research. This discontinuity between common names and scientific names is no better illustrated than in the naming of cedars of North America. You have, no doubt, heard of the cedars of Lebanon and their use in the building of Solomon’s Temple. We are at least familiar with the name, if not the tree. The first Europeans to arrive in North America were likely familiar with the tree, or more to the point, the wood. Cedar wood is known for its fragrance and resistance to rot. Early settlers to the East Coast found trees there that had these same characteristics. So it is perfectly natural that they would call them “cedars.” And from the standpoint of classifying wood uses, it is a perfectly reasonable name.


Deodar cedar
Now we realize that these North American cedars are unrelated to the cedars of Lebanon. They are not even in the same family. The old world cedars are in the pine family (Pinaceae). The true cedars, that is, those of genus Cedrus, are native to the Himalayas and the Mediterranean region. They include 2 species often planted as ornamentals:



Cedar of Lebanon
Deodar Cedar (Cedrus deodara) -- native to the western Himalayas. It has 2-inch needles.
Cedar of Lebanon (Cedrus libani) -- native to the mountains of Lebanon, Syria and Turkey. Atlas Cedar, native to the Atlas Mountains in northern Africa is usually considered a subspecies (Cedrus libani subsp. atlantica). The needles of this species are about 1-inch long.
All the true cedars have bundles of needles that grow on short stems, like larch needles. The cones of the cedars look and act like fir cones. They sit upright on the branch and disintegrate as they disperse their winged seeds. Deodar Cedar is a common urban conifer in the Northwest. Cultivars of the cedars are also popular, mostly dwarf-sized varieties that have blue needles. In contrast to the true cedars, all of the cedars of North America are in the cypress family (Cupressaceae). So what should we call them? Some have called our cedars “false cedars,” and tried to distinguish them from the “true” cedars with unconventional typographical notation (“western redcedar” and “incense-cedar.”) However, we must recognize two things: 1) Common names arise from common usage and do not reflect scientific classifications. This a major reason why we have scientific names. 2) You cannot just decide to change common usage. Consider this riddle: If you call a horse’s tail a leg, how many legs does a horse have? Answer: Four. Calling a tail a leg doesn’t make it a leg. When listing the common name for a tree, it’s best to just report the common usage.


Alaska cedar
Our cedars are not the only trees with this disconnect between common usage and the scientific name. Douglas fir is not a true fir. Wollemi pine is not a pine. Norfolk Island pine? Not a pine. Hemlock trees are not related to the poisonous plant they were named after. So what about our cedars? Several native trees in North America are commonly referred to as cedars. That is their common name. It may be confusing, but it is what it is. For clarification, it is good to give their scientific names and note that they do not belong to the the genus of the true cedars, Cedrus. To distinguish the cedars of North America from the old world cedars, I refer to them as “new world cedars.” This way of distinguishing them has precedent going back to the seventeenth century. In his book New English Canaan, published in 1637, Thomas Morton wrote, “New World Cedars are not true Cedars, but are of the Cypress family….” Although the new world cedars are all members of the Cypress family, they don’t share a common new world cedar genus. In the Pacific Northwest, we have four native cedars and none of them are classified in the same genus. Yet they all have a similar look to them. They have similar looking flat, scale-like leaves that grow down the twig like shingles on a roof. You can easily distinguish the native cedars from other conifers just by looking at these leaves. The branchlets have a similar drooping look in varying degrees. And they are all particularly aromatic, although each has its own distinctive aroma.


How to identify native cedars of the Northwest
In northwest Oregon and western Washington below 2000 feet elevation, any cedar you find is a western red cedar. In the Cascades, it gets more complicated. You will also find Alaska cedar there, and south of Mt. Hood, incense cedar. The other native cedar is Port Orford cedar, which grows in southwest Oregon, especially near its namesake.


Western red cedar (Thuja plicata) has flat, wide scale-like leaves, often with a white butterfly-shaped pattern on the lower surface. The 1/2-inch cones sit on top of the branch and look like tiny rose buds. The red-brown bark is stringy.


Incense cedar (Calocedrus decurrens) has longer tapered leaves. It has bark that looks similar to western red cedar but is deeply furrowed on large trees. The best way to identify incense cedar is by its unique cones. They are shaped like a duck's bill, and when they mature, they open, showing the open bill with its tongue sticking out.  



Alaska cedar (Callitropsis nootkatensis) has small, round cones and scruffy looking gray bark. When crushed, the foliage has a distinctive, unpleasant odor. Alaska cedar is also called yellow cedar, which describes its yellow wood.





Port Orford cedar (Chamaecyparis lawsoniana) has small round cones like Alaska cedar. The leaves often have a unique, white X pattern on the lower surface.

Did you notice the cedrus embedded in the genus name of incense cedar? Calocedrus means beautiful cedar. Even the scientific name suggests a close relationship to the genus Cedrus. Scientific names can be misleading, too.

Saturday, April 25, 2015

Focus on Western Hemlock

Western hemlock (Tsuga heterophylla) is one of the most delicate and beautiful conifers of the Pacific Northwest. For all its beauty, the hemlock is a humble tree. While the firs and spruces point their rigid leaders skyward, the top of the hemlock droops in a most self-deprecating manner. Its sprays of needles have a tendency to delicately droop in a similar way, often adorned with tiny cones. These hemlocks also tend to live a humble life for many years, living in the shadow of tall Douglas firs. Eventually some event may remove the dominant Douglas fir, giving the hemlock a chance to grow tall and flourish.
Hemlock History
Hemlocks originated in Asia around 30 million years ago. At one time, they were common throughout the Northern Hemisphere. Eight species remain, four in North America and four in eastern Asia. Two are native to the Pacific Northwest: western hemlock and mountain hemlock. One unexpected detail about hemlock relationships: The two species that are native to the east coast of the U.S. and Canada are more closely related to the hemlocks of Asia than to the Pacific Northwest natives.

Appearance
Needles: The short, flat needles of western hemlock are variable, as suggested by its scientific name, heterophylla. While the needles tend to lie flat, they do so grudgingly, sometimes refusing to at all and growing helter skelter all around the twig, pointing in any direction. The needles also vary in length, but each needle consistently displays a dark green upper surface and two white bands on the lower surface.



New and old cone
Cones: Western hemlock cones confirm its humble reputation. The cones are less than an inch long with rounded, thin scales. On the other hand, the tree is a prolific producer of cones. You can often find them even on the lower branches. If you look closely in the spring, you may also find some tiny pollen cones hiding in the needles. The seed cones open in the fall and drop their seeds. Each seed has a small wing attached and can travel over a mile in a strong wind. Old cones often remain on the tree for another year. If you don’t see any cones on the tree, look on the ground. It is often covered with a layer of old cones.

Pollen cones
Bark: The gray bark develops small furrows on large trees. Hemlock bark is thin and does not protect the tree from fire like the bark of Douglas fir.

Where it grows
Western hemlock is the state tree of Washington. It is common in the western parts of both Washington and Oregon, especially thriving in wet regions. It grows at lower elevations and up to 4000 feet, where it is replaced by mountain hemlock. Two adaptations enable western hemlock to thrive: It is shade tolerant and its seeds can germinate in organic material.

Unlike Douglas fir, which requires bare soil for its seeds to germinate, western hemlock seeds will germinate in soil with a thick organic cover. You will even see a young western hemlock growing on a rotting stump or log. You can recognize older trees that started on these "nurse logs" by the airborne roots that continue to straddle the absent nurse log long after it has rotted away.
Western hemlock growing on stump near a large Douglas fir
Western hemlock is one of the most shade-tolerant trees in the Northwest. Once a seedling is established, it can survive for years, growing slowly in the shade of large Douglas firs. A Douglas fir cannot live forever, and it cannot reproduce in a dense forest with no bare soil where the seeds can germinate and not enough sunlight for them to grow. Eventually, the old Douglas firs will die and the western hemlock will have their place in the sun. Then they can grow faster than a Douglas fir. Given enough time, western hemlock always wins in any competition with Douglas fir. Then the hemlock forest can grow and regenerate in perpetuity until a catastrophic fire burns all the trees and creates conditions for a new generation of Douglas fir to grow.

Along the coast, western hemlock competes with Sitka spruce. While the spruce are dominant at lower elevations where they tolerate salt spray, as the elevation increases, so do the hemlock, often becoming a pure stand. You can see this transition clearly if you hike the trails above the Visitor Center at Cape Perpetua on the Oregon Coast.

A western hemlock can grow to 200 feet tall with trunks over 8 feet in diameter. After 300 years it stops growing taller, but can live another 200 years. The oldest is over 700 years old, located in the Queen Charlotte Islands.

Uses
The first inhabitants of the Pacific Northwest made many uses of western hemlock. The inner bark was a source of tannin, used in tanning hides. They used dye from the bark to color baskets and wool. They carved the wood into tools and spoons. The branches were used as bedding material, a good thing to remember if you are ever lost in the woods. Alaska natives made bread from the inner bark. Coastal tribes placed branches in tidal waters to collect herring eggs.

Framing for a deck
Today, western hemlock is an important timber species, used to make lumber and plywood. You will often find lumber at your local lumber yard that is sold as “Hem-Fir,” indicating that it is either hemlock or fir. The white, soft wood is easy to work with and stain to any color, which makes it an ideal choice for baseboards, door and window casings, and other mouldings. The pulp is used to make high-quality paper and is the source for making cellophane, rayon, and plastics. Western hemlock is a popular landscaping tree, both in its native range and in many locations around the world. David Douglas introduced western hemlock to Britain after he discovered it growing in the Pacific Northwest in 1826. 

Many wildlife species depend on western hemlock for food or shelter. Deer and elk browse the needles. Snowshoe hare, rabbit and mountain beaver browse the seedlings. Deer mice and many species of small birds eat the seeds. Western hemlock provides habitat for the northern spotted owl, northern flying squirrel and red tree vole. Cavity-nesting birds also use the trees.

Names
The common name arose because the smell of crushed hemlock foliage is similar to that of poison hemlock, an unrelated herb native to Europe and the bane of ancient Greek philosopher Socrates. The genus name, Tsuga, is Japanese  for “mother tree” and the name of the native hemlock in Japan. The species name, heterophylla, comes from Greek for "variable leaves" and aptly describes the variable length and orientation of western hemlock needles. If you think of the needles as being heterogeneous, you can remember the scientific name. Other common names: Pacific hemlock and West Coast hemlock.
Western hemlock on Elk Mt. west of Forest Grove, Oregon 
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More info and sources
Conifers of the World, James E. Eckenwalder
A Phylogenetic Analysis of Species Relationships in Hemlocks, the Genus Tsuga (Pinaceae),
Northwest Trees, Stephen F. Arno and Ramona P. Hammerly
http://www.conifers.org/pi/Tsuga_heterophylla.php
http://www.fs.fed.us/database/feis/plants/tree/tsuhet/all.html
"A Phylogenetic Analysis of Species Relationships in Hemlocks, the Genus Tsuga (Pinaceae)" Jordan David Baker (http://dc.etsu.edu/cgi/viewcontent.cgi?article=3143&context=etd)

Friday, March 20, 2015

Focus on Douglas Fir

The Douglas fir is an extraordinary tree. It is the state tree of Oregon and the most common tree in the Pacific Northwest. But to call it “common” belies its uniqueness. It is quite distinct from the true fir trees and quite unlike any other conifer genus. Its unique cones with their three-pointed bracts distinguish it from other trees. The thick, deeply-furrowed bark sets it apart from other northwest conifers. And its soft, bottle-brush needles and long pointed buds make it easy to distinguish from all the other conifers of the region.


The unique features of Douglas fir presented a puzzle to botanists for years. It has been called a pine, hemlock and spruce. Its scientific name changed 21 times as botanists attempted to determine how to classify the species. Although it has blisters in its young bark like the true firs, in many other respects it is quite unlike the firs. The cones look and behave more like hemlock or spruce cones than fir cones. But the three-pointed bracts on the cones and the thick bark clearly distinguish it from the hemlocks and spruces. In 1867, it was classified not as a fir, hemlock or spruce, but in a separate genus of its own, Pseudotsuga. Finally, after many more years of discussion and confusion, Pseudotsuga menziesii was adopted as the species name in 1953.

Ancient History
Pollen cones
The first Pseudotsuga evolved in northern Mexico about 50 million years ago. Douglas fir is closely related to the larch genus, which evolved from the pines. Douglas fir either branched from the same pine ancestors or from the larch. In either case, the two took quite different evolutionary paths, the larch becoming deciduous with bundles of needles, and Douglas fir growing evergreen needles that resemble those of the spruce.
After its departure from the larch, Douglas fir began a long journey north, with some branching off to southern California to a separate species that we now know as bigcone Douglas fir (Pseudotsuga macrocarpa). As the name implies, they have larger cones than the Douglas firs of the Northwest, although the trees are usually much smaller. Meanwhile, the trees that continued their migration to the Pacific Northwest became what we know as Douglas fir. It may seem odd to speak of trees migrating. They generally stay rooted in one spot. Yet even though the trees themselves don’t travel, their winged seeds do. When the cones ripen and open, they release seeds that flutter to the ground like tiny helicopters. Let’s just suppose that in 100 years a tree grows to be 100 feet tall and produces seeds the are blown 100 feet from the tree. Thus, the forest will move 100 feet in 100 years, or on average, a foot per year. At that rate, it would take about 5000 years to migrate one mile. It may seem impossible for this forest to migrate all the way to Oregon, until you consider that it had 50 million years to make the trip. At the conservative rate of one mile every 5000 years, these seemingly steadfast trees could travel 10,000 miles. And that is exactly what they did. Not content to linger in Oregon and Washington, they continued right up the Pacific Coast to Alaska and across the land bridge to Asia and all the way to south-central China. Along the way changing conditions led to several distinct species now growing in China and Japan.
Meanwhile back in the Pacific Northwest, Douglas firs have adapted to different conditions here. As they did so, they branched into two varieties:
  • Coastal Douglas fir (Pseudotsuga menziesii var. menziesii) grows in western Oregon and Washington from sea level up to 5000 feet. It also grows along the coast of British Columbia and in the coastal mountains and Sierras of California.
  • Rocky Mountain Douglas fir (Pseudotsuga menziesii var. glauca) grows from central Oregon to the northeast corners of Oregon and Washington between 2000 and 7000 feet. The needles of this variety tend to be blue or gray compared to the coastal form. The bark is darker, and the bracts tend to protrude outward from the cones. This variety also grows throughout the Rocky Mountains up to elevations of 9700 feet. It grows even higher in the White Mountains of California, up to 10,000 feet. The highest growing trees of the species are in Arizona and Mexico, growing up to 10,700 feet.
Douglas fir is historically a fire-dependent species. Since it is not shade tolerant, it depends on fire or some other disturbance that opens up the canopy and leaves bare soil for its seeds to germinate. Once established, Douglas fir can dominate a stand of forest for several hundred years. Its thick bark helps it resist fires that often kill other conifers. Barring another disturbance, shade-tolerant trees such as western hemlock growing in the understory will eventually become dominant. Douglas fir is widely planted in many locations around the world, where it is grown for timber. Europe has more stands of Douglas fir than any other introduced species. The species has also been planted in a number of locations in the Southern Hemisphere, most notably in New Zealand, where it is sometimes considered to be invasive.

Discovery and Names
Archibald Menzies introduced Douglas fir to the scientific world when he found it growing on Vancouver Island and retrieved specimens in 1791. Menzies didn't collect any seeds or cones, but David Douglas collected Douglas fir seeds in 1826. These seeds introduced the cultivation of Douglas fir in England. Douglas is honored in the common name for Douglas fir. Menzies is honored by the scientific name, menziesii. The genus name, Pseudotsuga, means "false hemlock." Botanists often write the common name as "Douglas-fir" to indicate that it is not a true fir. Other common names: Oregon pine, red fir, and red spruce.
Big Tree at the Oregon Caves
Old Giants
Coastal Douglas firs can live to be 1300 years old, and commonly reach an age of 750 years. The oldest tree on record grew near Mount Vernon, Washington. It was about 1400 years old when it was cut down in 1913. The tallest tree in the world is a redwood that is 379 feet tall. But a Douglas fir that was cut down in 1902 near Vancouver, British Columbia measured 415 feet tall. Another tree cut down in Whatcom County in Washington in 1897 was reported to be 465 feet tall. The tallest living Douglas fir is a 327-foot tree growing in Coos County, taller than any conifer in the world except for the California redwoods. Another notable Douglas fir is the Big Tree at the Oregon Caves National Monument. It is 13 feet in diameter, but only 160 feet tall. You can find some fairly large Douglas firs in Portland's Forest Park, the largest next to the Stone House at mile 5.5 on the Wildwood Trail.


Uses Douglas fir is the Northwest's most important timber tree. Its strength makes it ideally suited for structural timbers and framing lumber in home construction, and its fast growth make it a favorite of foresters. If you live in a wood-framed house, it was very likely built from Douglas fir lumber. The species is also a popular Christmas tree, mostly because it is typically less expensive than other species.
Standing Douglas fir trees also provide a home for many animals and birds. Many cavity-nesting birds nest in Douglas fir snags. The red tree vole lives in mature Douglas fir trees, usually spending its entire life in a single tree, where it feeds primarily on the needles, and builds a nest high in the tree. Several individuals often inhabit a single tree. The red tree vole is a major food source for the spotted owl, which also nests in mature Douglas fir forests. The marbled murrelet is a sea bird that nests on large limbs of old Douglas firs.
Douglas squirrel with cone cob
After Douglas fir cones open and disperse their seeds in the fall, small mammals and birds eat most of the seeds. While the chipmunks and mice compete for these seeds, one notable denizen of Douglas fir forests takes its seed consumption to a higher level. This enthusiastic consumer of Douglas fir seeds is the Douglas squirrel. These squirrels harvest the cones before the seeds are dispersed. One will cut off a nearly ripe cone, scramble to a favorite branch, deftly cut away the cone scales and eat the seeds in a matter of five minutes. You can often find the results of this orgy in large piles of the scales and cone cores or what I call “cone cobs.” But the Douglas squirrel is not just a seasonal consumer of Douglas fir seeds. It will cut down quantities of cones and cache them in a wet place on the ground for winter consumption. If you listen carefully, you may hear the distinctive call from a squirrel high in the tree claiming ownership of cones, tree, and forest.
Since Douglas fir trees are so ubiquitous in the Northwest, you will have no trouble finding them whenever you hike in the woods. Look for the thick bark and check on the ground for cones with three-pointed bracts. And listen for the sharp call of the Douglas squirrel. They may have no title or deed, but they know that the forest belongs to them.
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More info and sources
Douglas-fir: The Genus Pseudotsuga by Denis P. Lavender and Richard K. Hermann, 2014, Oregon, Forest Research Laboratory, Oregon State University, Corvallis. Available online here:
Haunted Hikes by Andrea Lankford (Big Tree info)