Trees are taking over iconic meadows
OSU researchers say warming climate is causing changes at Jefferson Park

They arrive from every corner of Oregon — and even from across the country — on a remote gravel road just outside the Mount Jefferson Wilderness.

Thirty cars line the small parking area at Whitewater Trailhead 68 miles east of Salem, their owners stepping into the bright sunlight on a recent Saturday wearing hiking boots and carrying backpacks for a journey into one of the Cascade Mountains’ most beloved hideaways.

“I’ve wanted to do this hike for a long time,” says Caitlin White, who made the trip all the way from Beaufort, N.C., after scouting the hike online. “The pictures looked just amazing.”

She’s wearing a smile as she speaks, which puts her in good company with everyone else at the trailhead. The prospect of hiking five miles uphill, after all, becomes a labor of love when the destination is Jefferson Park.

A 333-acre collection of subalpine meadows dappled with wildflowers, clear lakes and a delicate ecosystem, Jefferson Park sits at the base of Oregon’s second tallest mountain.

The chance to hike and backpack into the shadow of 10,495-foot Mount Jefferson, rising above the grassy meadows like a massive pyramid, is a yearly tradition for locals and a bucket-list experience for generations of Oregonians.

Prolific Oregon author William L. Sullivan — publisher of 16 books, including the “100 Hikes” series — first came here in 1967 with a Boy Scout troop. He has returned a dozen times.

“There are not many places in Oregon where you can sit right next to a mountain that fills up half the sky,” said Sullivan, who has explored trails in every corner of the state. “The same thing that makes Jeff Park so beautiful — the meadows that open up those amazing views — also makes it fragile.”

And something is happening to those meadows, which light up with wildflowers in late July and blaze with autumn color in September, that few people have noticed.

Slowly, they’re disappearing.

Research conducted by Oregon State University and published in the journal Landscape Ecology says Jefferson Park’s iconic meadows are being invaded by an increasing number of trees.

Warming temperatures and decreasing snowpack in the Cascade Range have provided better growing conditions for mountain hemlock, said Harold Zald, the lead author of the study — a local example of climate change’s impact.

The density of trees at Jefferson Park has increased from 8 percent in 1950 to 35 percent in 2007, Zald said, a trend likely to continue.

The changes represent a larger transformation taking place in alpine meadows both locally, including the Oregon Coast Range, and across the American West.

“We worry about the loss of old-growth forests and focus on endangered species, but meadows are a crucial part of forest biodiversity,” said Zald, a research associate in the College of Forestry at OSU. “They’re filled with species that can’t live anywhere else — that wouldn’t survive in a forest canopy — and when they are gone, they may be gone forever.”

Journey to Jeff Park

Zald first became interested in studying alpine meadows through recreation rather than science.

An avid backpacker and hiker, the 38-year-old spent time camping and hiking high-elevation regions across the Pacific Northwest and was struck by what he saw.

“I kept finding all these young trees growing in alpine meadows,” Zald said. “I started noticing it 10 years ago but didn’t know much about it. The more I read, the more I realized that people were publishing papers about trees invading high elevation meadows in the Pacific Northwest, the Rocky Mountains and especially in Europe.”

In the study of climate change, alpine meadows would seem an odd subject. The consequences of global warming are typically dominated by stories of melting ice sheets and rising sea levels, severe droughts and rampant wildfires, along with increasing power in hurricanes, tornadoes and monsoons.

But studying meadows, Zald said, provides a good way to gauge long-term climate change. The meadows are more sensitive to changes and the impact tends to persist over extreme years that are wetter or drier, warmer or colder.

“It’s a good barometer of climate change over longer time periods,” Zald said. “And you’ll notice changes that you wouldn’t see in other parts of the forest.”

Research and findings

The Jefferson Park field research took place primarily in 2008 and included taking core samples of trees to determine age, measuring snow depth, examining topography and taking laser surveys to compare tree plots with other types of landforms.

Two intertwined elements emerged in helping explain why trees are invading Jefferson Park.

The first is that in 1934, a glacial dam on Mount Jefferson broke and a moraine lake poured down a debris flow of sand and mud that covered large parts of Jefferson Park.

The sediment from the debris flow created small, elevated hills more favorable for trees because the snow typically melts sooner.

“The trees came in much faster and much thicker where the debris flow came down,” Zald said.

The second has been more gradual and has occurred more recently. As temperatures have warmed — and as snowpack has decreased in the Cascades — the growing season has lengthened. The islands of older trees are expanding and new trees are germinating in areas they hadn’t previously.

“As you have less snowpack, that means you have increased chance for seeds to germinate and establish themselves in places where they might not have been able to in the past,” Zald said. “Very small changes of temperature can have big changes in the ability of vegetation to survive at different elevations.

“When you go to (Jefferson Park), you can really see it. The big trees are on the little ridges of the debris flow and the little trees are spreading everywhere except the very low, shaded areas where the snow persists later into the year.”

In a nutshell, the warming climate is allowing the forest to move higher on the mountain.

“There are two things happening right now — at Jefferson Park and throughout the Cascades — both caused by global warming,” Sullivan said. “The first is the melting glaciers, which sends down floods and (debris flows). The second is that warming allows trees to be able to grow at higher elevations.”

Jefferson Park isn’t the only local place where this trend can be observed. A study of meadows in the Oregon Coast Range — including places such as Mary’s Peak outside Corvallis — showed that “grass balds” had declined by an average of 50 percent between 1950 and 2000.

The future

So the question becomes, what will Jefferson Park look like in the future, and is there anything people can do?

Zald expects the trend to continue. Additional research conducted by OSU says by the middle of this century, snowpack will drop by 56 percent in the Cascade Range and the average date of peak snowpack will be about 12 days earlier. That likely will improve growing conditions for trees.

Brad Peterson, wilderness manager for the Detroit Ranger Station in Willamette National Forest, said cutting down the trees wouldn’t be a likely solution.

“Trying to revert the ecosystem to achieve a state that existed in the past isn’t a place that we would go,” Peterson said. “In wilderness, we’re not supposed to try and control natural environmental processes.”

Even so, it’s not a totally bleak situation.

“It’s really a glass half-empty, half-full situation,” Zald said. “The negative side is there’s a strong relationship between snowpack and tree invasion, and all the climate models are predicting less snowpack.

“But there are still going to be specific locations where the snow can pile up, in shady depressions where topography will allow snowpack to persist and the meadows to persist.”

In other words, 50 years down the line, people stepping into the Saturday sunlight at Whitewater Trailhead still will be able hike five miles down the trail to Jefferson Park.

The trees might be denser, the patches of wildflower-dappled meadows less plentiful, but Jefferson Park will endure.

What is a subalpine meadow?

Jefferson Park is known as a subalpine meadow, which means that it occurs right at the intersection of high elevation forest and alpine regions (above treeline).

In the Oregon Cascade Range, it typically can be found between 5,000 and 7,000 feet. The meadows are lush and include black alpine sedge (carex nigricans), thick, grassy foliage, along with unique wildflowers such as alpine aster and mountain gentian.

Hiking Jefferson Park

The easiest route begins at Whitewater Trailhead southeast of Detroit and requires five miles (or 10 miles round-trip) on a moderately difficult climb that gains 1,800 feet.

Backpacking is popular, but people should only camp at designated campsites that are marked with posts, and remember to tent 100 feet away from bodies of water. Please stay on the trail and do not go tromping off onto the fragile grasslands.

Information: Detroit Ranger Station, 503-854-3366

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