Posted tagged ‘Larch casebearer’

The Larch!

October 22, 2018
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Western larch light up Mount Hood’s eastern slopes each fall

The title of this post might take you back to “No. 1… THE LARCH” (followed by “No. 3… THE LARCH!” and “…now for something completely different…”).

This might have been the most obscure of Monty Python’s many recurring non-sequiturs, and it is indelibly imprinted in the minds of among those of us of a certain age… but the Pythons had it right: the larch isa remarkable tree, and it really can be “recognized from quite a long way away”.

At about this time each fall, Oregon’s only deciduous conifer explodes into shades of bright yellow, gold and orange before dropping its needles for the winter. Western larch (Larix occidentals) spends most of the spring and summer growing season blending in with other conifers in the forest, and are thus easily missed. But for the next few weeks, they will be flamboyantly on display, and are worth a visit to the east side forests they call home.

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Larch grove along the East Fork Hood River

Western larch is one of about a dozen larch found around the world, but it is the only larch found in Oregon. Its range extends north to British Columbia and east to Idaho, Montana and Alberta. It’s also among the largest of the larch species, capable of growing nearly 200 feet tall on massive trunks up to five feet across. Our Western larch is often called “tamarack” by locals, but that name actually belongs to a different, smaller species that grows in the eastern part of the continent.

Western larch has a distinctive shape compared to other forest conifers. Its crown is narrow and tapered, like a candle, and it often grows in groves were its shape allows closely spaced trees to thrive. Larch trees can survive extreme cold and thrive in subalpine forests with winters are frigid and summers are hot and dry — exactly the climate found on the east slopes of Mount Hood. Here, Western larch often dominates the forests and form the westernmost reach of the species.

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Larch seedling on Lookout Mountain

Western larch is also prolific in producing offspring, with thickets of young larch growing among the big trees, especially after fire or logging. Young trees are fast-growing, often adding a foot or more of new growth each year.

The branches of Western larch are unique and easy to spot, even during its “green” phase in spring and summer. New growth emerges bright yellow-green in spring from rows of knobs along its limbs, with clusters of needles held in tufts that emerge from each knob. This gives the foliage a delicate, lacy appearance during the growing season, when its foliage gradually deepens to dark green.

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Western larch are easy to spot by their tufted foliage

Their bare limbs have distinctive,  gnarled, picturesque shape in winter, when the needles have dropped. The cones of Western larch are small, and also arranged among the small knobs that dot its limbs.

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Western larch foliage

Mount Hood’s east side forests are also “fire forests”, ecosystems where frequent fires are essential to forest health. Like the neighboring Ponderosa pine that it typically associates with, Western larch has thick bark designed to protect mature trees from repeated fires. For added fire protection, larch drop their lower limbs at the tree mature, keeping the growing tree canopy high and out of reach of fires sweeping through the understory.

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The bark on Western Larch is thick and fire-resistant, similar to its Ponderosa pine neighbors

But in the recent catastrophic fires that have swept through the east and north slopes of Mount Hood, the flames were intense enough to reach larch canopies, killing thousands of these normally fire resistant trees. Despite this, young larch seedlings are among the most prominent trees leading the forest recovery in the aftermath of the Bluegrass Fire (2006), Gnarl Fire (2008) and Dollar Lake Fire (2011) that burned most of Mount Hood’s eastern and northern flanks.

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Western Larch shed their lower limbs, keeping their growing crowns out of reach of low-intensity fire that would likely burn the other, low-branched conifers in this forest near Hood River Meadows.

Western larch can live to be at least 1,000 years old — that’s the age of “Gus”, the largest and oldest larch of any species in the world. Gus is a Western larch [link=https://crownofthecontinent.natgeotourism.com/content/gus-worlds-largest-larch-tree/cot50caf093bd65f401b]growing in a grove of ancient larch survivors[/link]in Montana, and is at the heart of a magnificent larch grove that should be on every big tree hunter’s “bucket list”.

Mount Hood’s most venerable Western larch might be the stunted patriarch growing from a high rock outcrop along Surveyors Ridge (below) at a spot I call Tamarack Rock (an explanation for that improper name is found in this 2009 blog article), where it enjoys a magnificent view of Mount Hood, but also endures the brunt of Pacific storms sweeping across the Cascades in winter and intense heat and drought over the summer months. This old tree is likely centuries old, and has survived fires, logging and undoubtedly a few lightning strikes is this exposed location.

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Ancient larch on Tamarack Rock

Like most of our native species, the Western larch was used by Native Americans for food and materials. The resin under its bark was used for medicinal purposes and larch wood was used for poles and as firewood. Today, it is still prized as exceptional firewood.

Which brings us to perhaps the most unfortunate threat to Western larch in our increasingly busy forests: being cut down as “dead” during its dormant, leafless winter phase. Too many perfectly healthy larch trees meet this completely avoidable fate in our forests and cities each year.

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These oddly shaped larch near Brooks Meadow have been attacked by the Larch casebearer, an introduced European moth that can defoliate and even kill Western larch.

A more worrisome threat is the Larch casebearer, a European insect that can defoliate Western larch. The parasites that keep the casebearer in check in Europe has not been effective as an introduced counter measure in the Western larch range, and the long-term impact of this introduced bug on our larch stands is still unknown.

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Larch stand in mid-summer with browned foliage from a heavy attack by Larch casebearer

The photo above looks like it might be a larch grove in fall, but the photo was taken along the Lookout Mountain Road in mid-summer, showing the crowns of several Western larch under heavy attack by the Larch casebearer. The State of Oregon has published this fact sheet with more information on the casebearer.

Where to see Western Larch

From now through early November, Western larch will be putting on a show along the eastern leg of the Mount Hood Loop Highway, where OR 35 follows the East Fork of the Hood River to Bennett Pass. Bennett Pass roughly marks the dividing line for its range, with big stands of larch suddenly appearing east of the pass.

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Larch trees fading to orange and gold in November along the Gumjuwac Trail

If you have more time, the Dufur Mill Road (Forest Road 44) has still more Western larch on display, including along the unimproved road to High Prairie on Lookout Mountain. And if you simply travel Highway 26 across the Cascades, you’ll see Western larch from Blue Box Pass east to the edge of the forest.

If you’re looking for a trail to hike or ride a bike through larch stands, the Dog River Trail (No. 675) and Zigzag Trail (No. 678) are good choices. Both are quiet, though you’ll share the Dog River Trail with mountain bikers. Other trails along the East Fork also offer nice larch stands.