As he picks his way down the trail in a light rain, Scott Hopkins keeps glancing through breaks in the forest canopy, eyes scanning a densely wooded slope on the far side of the river.

Here in the Valley of the Giants, a protected pocket of public land about 30 miles west of Salem, there is an unusual concentration of massive old growth conifers. But somewhere on that mist-shrouded hillside, Hopkins believes, may be the biggest of them all.

“There are some big ones out here,” said Hopkins, a biologist with the Bureau of Land Management, the federal agency that oversees the area. “Most of the biggest ones are right around 280 feet, but there may be a 300-footer out here.”

Locating the biggest tree in the Valley of the Giants is a matter of professional interest to Hopkins, who’s made countless trips to the area since coming to work for the BLM in 1987. The previous reigning champ, a monumental Douglas fir known as Big Guy, blew down in a windstorm in 1981. At a shade under 230 feet, it was far from the tallest tree in the valley, but its impressive girth — more than 11 feet in diameter at breast height — made it the king of this particular forest.

It was never the biggest tree in the state — that honor belongs to the Doerner fir, a towering specimen found on BLM land in Coos County that measures 11½ feet in diameter and rises to a dizzying 327 feet, 3 inches, making it the tallest known conifer in the world that’s not a redwood.

That being said, there are few places in Oregon — or anywhere else, for that matter — where you can see more big trees than the Valley of the Giants.

Saved from the axe

Perhaps the most remarkable thing about this isolated grove is the simple fact of its survival in the midst of an industrial logging zone. Viewed from above, it appears as a small island of primeval forest in a sea of clearcuts and second-growth timber plantations.

This remnant stand of old growth likely would not exist today if not for the vision and passion of Maynard Drawson, a big tree hunter from Salem who died in 2012.

A barber by trade, Drawson first heard about the area in 1974 from one of his customers, a BLM forester named Guy Higginson. The agency had recently pushed a new logging road into the tall timber on the North Fork of the Siletz River near the Polk-Lincoln County line, and Higginson had heard rumors of gargantuan Douglas firs in the region.

After some persuading, he agreed to take Drawson out to explore the area. Armed with a measuring tape and a clinometer (a timber cruiser’s instrument for estimating tree height), they drove to the end of the road and plunged into the woods. Right away, Drawson realized he was in a special place.

“Almost immediately I felt the same sense of excitement sweep over me that usually accompanies a new treasure discovery,” Drawson wrote in “Treasures of the Oregon Country 4,” the 1974 installment of his five-volume series of memoirs.

“Giant trees were everywhere. … Never had I seen a stand of Douglas firs collectively approaching the size of the ones we were now measuring.”

The two men taped a dozen trees measuring more than 25 feet around the trunk, including Big Guy, named in Higginson’s honor and coming in at a whopping 35½ feet in circumference. Recognizing that these forest titans could be logged at any time, Drawson launched a crusade to save them from the axe.

Drawson lobbied tirelessly to preserve the spectacular grove, buttonholing BLM officials, writing letters to politicians and newspaper editors, organizing tours for the public and the press. It took two years of hard work, but in the end his efforts paid off. In 1976 the Bureau of Land Management set aside 51 acres for protection as the Valley of the Giants Outstanding Natural Area.

A walk in the woods

Forty-one years later, the Valley of the Giants remains as remote as ever. The price of admission is a long drive over unpaved logging roads that can be hard on low-clearance passenger cars and are typically closed during fire season (see accompanying story on page A6).

But the reward is a chance to spend some quality time with some truly impressive trees.

Today’s visitors can explore the area by means of a well-marked trail, a 1.3-mile out-and-back route that winds its way downhill before crossing the North Fork Siletz on a steel and timber bridge, where a picnic table makes a good place for lunch. From there the trail climbs a short distance up the opposite hillside, making a lollipop loop and returning to the parking lot. There are no restrooms or garbage cans, so all trash (including toilet paper) must be packed out.

Within a few steps of the trailhead you find yourself swallowed up by the forest, a riotous tangle of green that surrounds you on all sides. A carpet of wood sorrel, Oregon grape and false solomon’s seal, spangled in summer with the six-pointed white blooms of queen’s cup, covers the forest floor. Sword ferns and bracken, huckleberries and devil’s club mix with vine maples and young conifers in the understory. Big-toothed maple, Western red cedar, red alder and other trees come together to form a leafy ceiling overhead.

Suddenly, the first big trees loom into view. Massive, moss-encrusted trunks rise up through the forest canopy like the pillars of a living cathedral, with an estimated five to 10 trees per acre soaring above 200 feet.

The biggest — the true giants — are Douglas firs, but Western hemlocks are a close second in terms of height and girth, and they may actually be more numerous as the forest approaches climax stage. Eventually, the faster-growing hemlocks could come to dominate by shading out young fir trees.

It’s not easy, Hopkins notes, for any tree to grow so large. It has to avoid being cut down, burned down, blown down, knocked down or ravaged by any number of pests and diseases.

“After about 200 years old, it’s just fighting this constant battle of maintaining itself,” he said. “It’s got to fight this battle year-round to obtain enough sunlight and soil moisture to maintain itself while fighting off root rot and other diseases.”

One factor in the proliferation of big trees found here is the area’s unique combination of topography and weather patterns. The Valley of the Giants ranges in elevation from about 1,500 feet in the river bottom to more than 3,500 feet on the surrounding ridges, which wrap the valley in a protective C-shaped embrace to form a natural buffer against high winds and spreading wildfires. Deep soils and 180 inches of average annual precipitation provide excellent growing conditions, while ocean breezes blowing off the nearby Pacific provide a moderating influence that blunts the impacts of summer heat waves and winter frosts.

Another factor is simple good fortune. For whatever reason, this isolated valley has gone for centuries without any major natural disturbance such as fire, earthquake, landslide or insect infestation. And that has allowed some of the trees here to grow very, very old.

Precisely how old is difficult to say with certainty. An increment bore could provide an accurate measurement without harming the tree — but they don’t make increment bores big enough to take core samples from a behemoth with a 12-foot diameter.

The alternative is to saw through a downed tree and count the annual growth rings. The problem with that is, on a really big tree the outer rings are jammed so close together that they can be extremely hard to count.

“I’ve gotten to 375, 380 and I’ve still got a quarter-inch to a half-inch of wood left, where there might be another 50 to 100 years,” Hopkins said. “Some of these trees might date back to the early 1500s.”

In other words, they were seedlings when Europeans were just beginning to explore the Americas. That doesn’t make them the oldest trees in the New World — there are redwoods that have been dated to 2,200 years old, junipers to 2,600, sequoias to 3,200 and a bristlecone pine in California’s White Mountains that is considered the oldest living tree on the planet at age 5,066.

But at the half-millennium mark, the patriarchs of the Valley of the Giants preside over an emerald empire that feels like something from another place and time.

“If you’ve got a 500-year-old forest, you’re liable to have something that’s really magnificent,” Hopkins said. “A 200-year-old forest is magnificent. A 300-year-old forest is magnificent. But a 500-year-old forest is really something special.”

The towering firs and massive hemlocks aren’t the only big trees here, although some of the other contenders may not be so obvious.

“One of the interesting things about big trees is that not every tree grows in a growth form that you can really measure,” Hopkins said.

It’s a lesson he learned on a visit to the Valley of the Giants about 15 years ago, when he and a fellow BLM biologist were conducting a spotted owl survey.

“I was sitting on a log over there,” he said, pointing to a thicket of sturdy-looking vine maples, “and the log kind of … levitated. I thought, ‘Whoa! That’s weird.’”

His friend, perched atop another log nearby, noticed the same thing. On closer inspection, the two men realized they were sitting on the horizontal trunks of a living tree with five main branches, several of them 9 to 11 inches in diameter.

“We ended up tracing down the branches of what may be a pretty significant old growth vine maple,” Hopkins said.

Could it be a record holder? The tree’s multiple trunks and sinuous shape make that difficult to gauge.

“There’s probably some kind of formula,” Hopkins said, “but I figured I’d leave it to the big tree guys.”

Signs of life

This forest is full of smaller organisms as well. At a likely-looking spot along the trail, Hopkins sets a timer on his smart phone to do a five-minute bioassay of life on the forest floor. Rummaging around in the deep layer of duff beneath a towering stand of trees, he turns over fallen slabs of bark in search of mollusks, insects and terrestrial salamanders.

“I’m interested in anything creepy-crawly,” he explains.

He turns up a few snails and slugs, then gets excited when he uncovers a black ground beetle roughly half an inch long. This particular species, Promecognathus laevissimus, has an unusual relationship with Harpaphe haydeniana, the yellow-spotted millipede.

Growing up to 2 inches long, these black-and-yellow ground crawlers are common in moist forests of the Pacific coast from Alaska to California, where they play a vital role in breaking down fallen leaves and rotting wood. Due to their ability to secrete small amounts of cyanide, they have almost no natural predators — except for P. laevissimus, which is immune to the toxin and actually remanufactures cyanide from the millipedes it munches into a boric acid-like compound for its own chemical defense system.

Today’s critter count is low, but that doesn’t necessarily mean anything.

“There’s some species out here I feel like I don’t see as often as I did 15 years ago,” Hopkins says. “Is that really a trend? I don’t know. We’ll just have to keep collecting that data.”

A little bit farther on, Hopkins bends down to examine the ground at the base of a massive Doug fir. He straightens back up holding a small clump of what looks like greenish-brown hair in his hand.

“What I’m finding here,” he says, “is evidence of red tree voles.”

The red tree vole — a small, nocturnal rodent native to moist old growth forests of Western Oregon and Northern California — spends its life in the treetops, where it lives on a diet of conifer needles. Most creatures find the needles inedible because of chemical compounds produced by their resin ducts, but the red tree vole has learned the trick of stripping away these structures and munching on the part that remains.

“Think of it as eating little tiny corn on the cobs,” Hopkins suggests.

The discarded resin ducts pile up in clumps beneath trees where voles have been feeding. Their presence here is a good sign — red tree voles are an important food source for the northern spotted owl, which has been listed as threatened under the Endangered Species Act since 1990.

But like the owl, the vole is under intense pressure from the loss and fragmentation of the old growth forests it depends on for survival. The Oregon Coast Range population of red tree voles is considered a candidate for threatened status as well — making protected enclaves such as this one all the more vital.

Long live the king

At the top of the loop is the area’s main attraction, the tree that put the Valley of the Giants on the map, now lying in state across the trail like a fallen king. Even in death it is an imposing sight, and Hopkins pauses to pay his respects.

“So this is Big Guy,” he says, “melting into the forest here.”

Melting is a good word for it. Some 36 years after a powerful windstorm brought down the centuries-old behemoth, the titanic trunk has begun to sink gently into the earth. A thick layer of green moss drapes the horizontal upper surface, where huckleberries, ferns and other small plants have taken root.

About a year after the Big Guy fell, a BLM crew cut out a slab roughly 2 feet wide and rolled it out to create a gap for hikers to pass through.

The huge wooden round lay on its side, serving as a picnic table for visitors for a number of years until the wood fibers, exposed to rain, insects and micro-organisms, deteriorated and the whole thing broke apart.

Hikers can still walk through the narrow passage, but it’s not as easy as it once was. Hopkins’ theory is that moisture has gotten into the tree’s interior, causing it to swell.

“I’d like to think it’s the tree and not me that’s gotten wider,” he jokes. “Now everybody I know has to go through sideways.”

Wriggling through the gap, though, inspires a kind of reverence. As your body passes through the heart of this fallen forest monarch, it’s impossible not to be impressed with the sheer immensity of this once-living being — and equally impossible not to wonder if there might not be a worthy successor awaiting discovery somewhere in these woods.

Last year, the BLM adopted a major revision of the management plan for its Western Oregon region despite strong opposition from environmentalists, who objected to provisions that allowed increased levels of timber harvesting.

But Hopkins notes that it also provided a mechanism for preserving significant stands of older trees. As a result, the Valley of the Giants was enlarged to 1,667 acres under a protective designation called an area of critical environmental concern, or ACEC for short.

With the expanded area came an expanded pool of contenders for the title of new king of the forest. Using lidar imagery, Hopkins has been able to determine that there are 240 trees over 200 feet tall in the original 51-acre outstanding natural area — and a staggering 4,300 in the new ACEC.

Lidar — a relatively new surveying technology that uses light-detecting sensors and range-finding lasers to create three-dimensional maps of an area — is both easier to use and more accurate than the old timber cruiser’s clinometer for measuring the heights of trees. And the lidar images Hopkins has looked at has revealed a number of specimens over 280 feet and a few that top out above the 290 mark.

“The heights of some of these trees are just astounding,” he said.

But lidar won’t give him a reading on a tree’s diameter at breast height — to get that, he’ll have to go deep into the woods with an old-fashioned tape measure. And calculating crown spread — the other crucial dimension in determining whether a tree deserves a place in the record books — may require the use of technical climbing gear to get right up into the upper branches.

Still, there’s reason to believe that another tree to rival or perhaps even surpass Big Guy may be waiting in the wings.

According to Jerry Black, the volunteer data manager and verifier for the Oregon Champion Tree Registry, BLM foresters located an awe-inspiring Douglas fir just a few miles to the east in the mid-1960s. Dubbed the Polk Fir, it was measured at 12 feet in diameter and 240 feet tall — which would make it even bigger than its more famous neighbor.

But this impressive specimen fell off the big tree radar shortly afterward with the discovery of an even bigger fir, and Black said he’s not sure whether it’s still standing.

Hopkins, meanwhile, has his own ideas about where to find a new king (or queen) of the Valley of the Giants, and he doesn’t think he’ll have to go very far to do it.

“I think there’s a possibility on that slope that had Big Guy that’s his big brother or sister,” he said. “But I haven’t taken an exact measurement.”

Reporter Bennett Hall can be reached at 541-758-9529 or bennett.hall@lee.net. Follow him on Twitter at @bennetthallgt.

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