Paul Nieman of Ligonier and his yellow Lab, Lily, hike all around Forbes State Forest, but one spot they visit repeatedly is Spruce Flats Bog.

On a late summer trek around Laurel Summit State Park, Nieman was going to skip it, but Lily insisted on leading him down the ¼-mile trail from the parking lot to a boardwalk ending in an observation platform in the midst of the bog.

“It’s certainly a beautiful, quiet spot,” Nieman says of the 28-acre, roughly circular wetland. “And there are so many things growing here that don’t grow anywhere else.”

Due to its seclusion, it’s often overlooked by visitors to the surrounding forest, which is crisscrossed by hiking trails and points of interest such as the Beam Rocks and Wolf Rocks overlooks — although it’s a prime spot for viewing fall foliage, according to Dave Planinsek, a Laughlintown-based forester with the Pennsylvania Department of Conservation and Natural Resources.

The bog also is unusual for a number of ecological and geological reasons, says Rachael Mahony, a Forbes State Forest environmental education specialist.

Shirley McMarlin | Tribune-Review Forbes State Forest environmental education specialist Rachael Mahony leads tours of Spruce Flats Bog in Laurel Summit State Park.  

Unusual location

Bogs generally are found at lower elevations, Mahony says. Ringed by conifers and some deciduous trees, Spruce Flats sits in a depression in the rock surface of the ridge at 2,720 feet above sea level.

While conventional wisdom says the Spruce Flats depression was formed by glacial movement, that’s probably not the case, says Jim Shaulis, senior geological scientist with the Pennsylvania Geological Survey.

“We can’t say the ice itself never came down over the Laurel Highlands, but we’ve looked hard and haven’t found any evidence,” Shaulis says. “The evidence shows that the actual ice walls never got any farther down than Moraine State Park (in Butler County).”

The ridge-top rock more likely was worn down into a bowl-shaped depression by extremes of weather, both freezing and thawing, in the distant geological past, Shaulis says.

So what exactly is a bog? A bog is a wetland that receives its moisture from rainfall, rather than being fed by a spring or stream.

The bog accumulates a surface layer of dead and decayed organic matter known as peat, along with sphagnum or other types of mosses. Underneath are layers of water and mud. Due to the lack of fresh, flowing water, bogs are nutrient-poor and acidic.

Louis B. Ruediger Tribune-Review Cottongrass surrounds carnivorous pitcher plants.  

Bogs are home to highly specialized plants and animals that tolerate the waterlogged conditions and low nutrient levels. They are most commonly found in the cold and temperate climates of the Northern Hemisphere.

Thousands of years ago, water collected in the depression at the top of Laurel Ridge, according to a Pennsylvania Bureau of Forestry brochure about the site. Gradually, organic material collected and the bog formed, succeeded by a meadow and eventually a forest.

Shirley McMarlin | Tribune-Review Conifers and some deciduous trees ring the perimeter of Spruce Flats Bog in Laurel Summit State Park.  

Mistaken identity

About 1900, loggers arrived to harvest the virgin hemlock on the site, with a case of mistaken identity leading to the bog’s name.

“The English-speaking loggers called every tree that was a conifer a ‘spruce,’ ” says Ephraim Zimmerman, science director of the Natural Heritage Program at the Western Pennsylvania Conservancy. “Red spruce is the only spruce native to the Laurel Highlands, but it’s not there.”

In 1909, the Commonwealth of Pennsylvania bought the land and designated it a state forest. Foresters came up with a plan to drain the area by dynamiting through the underlying sandstone.

“I don’t know how many times they attempted to blow it up, but eventually they gave up and went on their way,” Mahony says, and the area gradually reverted back to bog.

Shirley McMarlin | Tribune-Review Water stands on the surface of Spruce Flats Bog in April.  

On a late August visit, Mahony pointed to a lone area of standing water in the middle of the bog, evidence of a dry summer.

“This year, we’ve had a bit of a drought, so the water is not as visible right now as in years past,” she says. “Some years it’s wet, and some years it’s dry, depending on the El Nino and La Nina cycles we go through.

“It’s a wetland, so there’s water in it, no matter how dry it is in Western Pennsylvania. But you can see that some of the trees are stressed, where the leaves are yellow or brown and will drop early,” she adds.

Rainfall quickly replenishes the water level, though.

Louis B. Ruediger Tribune-Review Sundew is one of two carnivorous plants growing in Spruce Flats Bog.  

Insect eaters

The bog is home to typical Laurel Highlands plants such as mountain laurel and rhododendron and wetland plants such as cranberries, bog St. John’s wort, rushes, sedges and other grasses, along with carnivorous sundew and pitcher plants.

The two insect-eaters are not native to the site, Mahony says. They were transplanted in the 1940s by the Botanical Society of Westmoreland County from the site of High Point Lake in Somerset County during the construction of the man-made lake.

Looking around the perimeter, visitors can spot hemlock, Atlantic white cedar, white and black pine, red oak, red maple and witch hazel trees, along with a few black gum trees struggling to survive.

“Black gum typically likes a drier ridge-top,” Mahony says. “It’s so waterlogged here that the trees can’t actively grow.”

Shirley McMarlin | Tribune-Review View of waterlogged Spruce Flats Bog in April.  

Animal life is abundant.

“It’s a great birding spot during migration,” Mahony says. “We hear a lot of barred owls.”

Keep your eyes and ears open, and you might identify owls and hawks; songbirds such as warblers, cedar waxwings and red-winged blackbirds; spring peepers, green frogs, salamanders and snakes; dragonflies, damsel flies “and plenty of mosquitoes and gnats,” she says.

Deer and the occasional groundhog or black bear are spotted around the perimeter.

Shirley McMarlin | Tribune-Review Cottongrass blooming in the fall at Spruce Flats Bog at Laurel Summit State Park in Cook.  

Bog or fen?

But is it really a bog, or is it a fen?

Just as early loggers called the Laurel Ridge hemlocks “spruce,” the bog itself might be similarly misnamed, Zimmerman says.

Bogs are not connected to any system of lakes or streams, while fens are connected to an outside source of slowly flowing water.

“We use the term ‘bog’ to refer to a wetland that is hard to get through, where you get bogged down,” he says. “A true bog has no influence from groundwater, and that’s not necessarily the case here.

“Could you call it a bog? Probably, but most Laurel Highlands wetlands have some input of groundwater, due to the springs throughout the area,” he said. “As conservation scientists, we’re always learning more about these places; and maybe some day we’ll be able to say it’s a true bog.”

Louis B. Ruediger Tribune-Review Pitcher plant flowers stand above cottongrass.  

Watch your step

Bog or fen, it’s a special place that needs to be treated with respect.

It isn’t safe for visitors to venture off the boardwalk and into the bog, Mahony says.

“We don’t know how deep this bog gets, the layer of decomposing plant matter is so thick. You can step on the sphagnum moss mass, then the next step you’re knee deep and then you’re hip deep,” she says.

Courtesy of Pennsylvania Department of Forestry This detail from a map of the Laurel Mountain section of Forbes State Forest shows Spruce Flats Bog as a collection of blue dots at lower center. The red dots trace the path of the Laurel Highlands Hiking Trail. This detail from a map of the Laurel Mountain section of Forbes State Forest shows the Wolf Rocks and Beam Rocks overlooks at top left and right, respectively, outlined in pink. Spruce Flats Bog is shown at lower center. The red dots trace the path of the Laurel Highlands Hiking Trail.  

“Visitors need to stay on the boardwalk to preserve the plants,” she adds. “The boardwalk gives you a 360 view. Everything you need to see is right here.”

“A peat-land wetland is a fragile area,” Zimmerman says. “It can’t take being walked on. These places can be loved to death because they are so fragile.”

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