Northern Light

At Oulanka National Park in Finland, a forest floor outshines the sky.

This story appears in the June 2009 issue of National Geographic magazine.

The next time I visit Oulanka National Park in the far north of Finland, I want to be two feet tall. That way the autumn mushrooms will come up to my knees, and I'll find myself walking in a waist-high forest of heather and lingonberries and crowberries and lichens. At that height, too, the wood-ant nests will tower over me. I will have to keep a sharp lookout for moose and reindeer, it's true.

Not that there's anything wrong with Oulanka at my normal height. Young Scotch pines grow on the slopes like closely spaced lances, and the old ones tower overhead, outgrowing the red of their bark as they age. The long winters and deep snows have trimmed the candle spruces into the slenderest of columns. In summer and fall the quiet northern light flickers on the leaves and the bark of silver and downy birches. This is the boreal forest, the forest that covers nearly all of Finland.

Here in Oulanka there is an uncharacteristic richness underfoot, a striking biodiversity, especially for a landscape that lies just a few miles south of the Arctic Circle. The main reason is limestone, an extrusion of youngish dolomitic rock—composed largely of carbonates—overlying the older granites and gneisses that make up the bedrock in so much of the rest of Scandinavia. The carbonate helps neutralize what would otherwise be acidic soils, and it adds critical nutrients. "Without the limestone," says Pirkko Siikamäki, head of the University of Oulu's Oulanka Research Station, at the heart of the park, "Oulanka would be just like the rest of Finland."

Instead, Oulanka is unlike almost anything else in the Finnish landscape, a place where a surprising number of biological zones converge. Because of its topographical diversity—high fells and low river valleys, mires, bogs, and alluvial grasslands—it is a kind of crossroads for species that normally do not overlap. Here is one of the few places where European, Arctic, and even Siberian species come together, mingling at the very edge of their ranges.

I came to Oulanka, as so many visitors do, to witness the grandeur of its glacial landforms—especially the canyons carved by the Oulanka River, which flows eastward through the park toward the border of Russia, just a few miles away. But the farther I hiked along the park's popular footpath, the Karhunkierros (Bear's Ring) Trail, the less I found myself noticing the major features of this landscape: the kettle holes—basins created by melting boulders of ice left behind by glaciers—or the gaping crevices worn away by the Oulanka River, or even the canopy of pine and spruce boughs overhead. Instead, I found myself lost in contemplation of the forest floor.

The word "floor" does not capture the intricacy, the complexity of this terrain. The word is too two-dimensional, too dismissive. This is not the flat, dry mat of needles you often find in the conifer forests of the American West. The needles you do see on the surface here—thrust aside by upspringing mushrooms or caught up in the leaves of a lingonberry—are like a roof of thatch on an interconnected, underground city. This is a place where the years can be measured in voles, especially the bank vole and field vole, which bore through the mass of low-lying plants at ground level. Some years vole numbers boom, thanks to abundant food and few disease outbreaks. A good vole year—plenty of voles everywhere—is good for just about every meat-eating member of the food chain: foxes, stoats, weasels, owls and other birds of prey. A bad vole year—and the past few years have been disappointing—is a bad year for predators in general.

In a sense, the forest in Oulanka is not made up of trees. The trees are woven together into a forest by the biotic community at their roots, by the stunning variety of beetles, plants, lichens, and mushrooms. These species are all sheltered by the canopy of branches above them, and in turn they help break down and circulate nutrients in the soil.

Above all, the forest is woven together by wood ants. One afternoon, near the aapa mires —the wet peatlands—on the sandy northern edge of the park, I sat and watched an ant colony at work. Its mound, some three feet tall, looked like the great shoulder hump of a brown bear with pine needle fur. The mound swarmed with small red ants making their way in and out of several entrances. The movement was so constant, so determined, that the entire mound seemed to be shifting in and out of focus before my eyes.

And yet this was just the superficial activity of these ants. In fact, their trails lead all over the forest: underground, aboveground, up the trunks of the trees, and out onto the highest branches. The ants recycle everything around them, including dead insects. They farm aphids for their honeydew. Wherever there are wood ants there are also richer populations of earthworms and richer nutrients in the soil. Brown bears tear the nests apart, foraging for grubs, and they have been known to hibernate in the soft earth inside the mounds.

In themselves, the ant colonies—some of which may be as old as Oulanka's mature trees—constitute large-scale organisms that suppress the presence of other insects. If all the biomass in an ant colony were concentrated into a single individual capable of wandering over the landscape and showing its true biological proportions, it would tower over even the biggest bear. In short, wood ants play a vital role in regulating the economy of the forest in Oulanka. They are its keystone species.

National parks preserve more than the life and scenery within them. They also preserve the cultural assumptions of the nations that create them. Like the rest of Finland's parks, Oulanka helps preserve an intense cultural bond with the forest, part of the annual, and deeply beloved, Finnish retreat to the countryside in summer and fall.

Throughout Oulanka—in its campgrounds, on its swinging bridges and well-groomed trails—I met hikers carrying bags of edible mushrooms they had gathered along the way. In an American national park such as Yellowstone this would be illegal. But the Finns cherish a custom called "everyman's right." Among other things, this allows any person to gather berries and mushrooms—though not wood or lichens or mosses—wherever they like, including Oulanka.

To an American sensibility, the reindeer are perhaps the most puzzling inhabitants of Oulanka National Park. Singly and in small herds, they move through the park grazing on mushrooms and lichens and green plants. The reindeer are soft gray in color, often with white hair growing down their legs to their hooves, which gives them the appearance of wearing spats. In this setting they look entirely natural, a Finnish version of mule deer or elk. And yet these are semidomesticated reindeer, sources of meat and pelts that wear ear tags and collars, whose owners will gather them in the fall and corral them through the winter.

All of Oulanka National Park is considered part of the local reindeer herding range. It's as though Colorado's Rocky Mountain National Park, which is just slightly smaller than Oulanka, were part of the local grazing district, and cattle were turned loose into its alpine meadows during the summer.

Corralling and feeding the reindeer during the winter has reduced the damage they do to the undergrowth in Oulanka. There is a feeling among some Finns, however, that the days of the reindeer herder are numbered, at least in this part of the country. The work is simply too hard, and the dividends too small.

For all its serenity—the quiet oxbows on the river, the deep stillness of the upland mires and spruce stands—Oulanka bears some scars of modern history. This is an old, old land, but a very young park, for Oulanka was established only in 1956. The locals can show you the sites of machine-gun emplacements high above the river, and they will remind you—with feeling that still seems very fresh—that the Finns fought the Russians bitterly in the early days of World War II. If you drive to the boundary zone, a metal gate blocks the road. But it does not block the geology or the biological communities that make Oulanka so rich. They continue across the border into what was once Finnish territory but is now a Russian national park called Paanajärvi.

Kari Lahti, the director of Oulanka National Park, talks to his Russian counterpart in Paanajärvi almost every week. Together they are trying to find a way to make the two parks one, from the visitor's perspective at least. Perhaps someday it will be possible to step into a canoe, slip away from the sandy banks of the Oulanka River, and drift into Russia, uninterrupted by anything more than a family of goosanders taking flight.

But you might not want to. Once you've seen a wood-ant nest, or the autumnal uprising of mushrooms, or the ground white with reindeer lichens, you may find yourself wandering among them in your mind, two feet tall in a realm where voles are the size of sheep and an acre of Oulanka is a whole world.