Photo Essay: Where the Trees Meet the Tundra

In northern Alaska, just past the arctic circle, boreal forest begins giving way to tundra. The largest ecological transition zone on earth, the so-called tree line circles the globe for more than 8,300 miles. On a June evening, Lamont-Doherty ecologist Natalie Boelman observes fast-changing weather closing in.

This region is reached via the Dalton Highway, one of the few North American roads that reach this far. Built in the 1970s to serve the arctic-coast oil fields, it ends more than 500 miles beyond Fairbanks, the nearest city. The Alaska pipeline, which channels oil southward, parallels the road to the right.

Further north, in a valley at the very edge of tree line in the mountains of the Brooks Range, scientists set up a laser-powered LiDAR camera to survey an acre or so. Its highly detailed 3D map of vegetation will provide information on subtle differences in topography and other elements that may allow trees to survive, or not.

Lamont-Doherty plant physiologist Kevin Griffin examines a spruce, the only kind of tree capable of growing here. “If temperatures keep warming, species might change, and trees might be able to grow further north,” says Griffin. “If that happens, there will be a whole suite of consequences for ecosystems.”

The tree line is altitudinal as well as latitudinal; trees living in valleys can’t survive higher elevations. Here on a windswept mountaintop above one of the team’s study sites, only plants typical of the lowland tundra further north hang on.

Lamont-Doherty grad student Johanna Jensen installs a dendrometer, which will record minute changes in this spruce trunk’s diameter over the next three years. The trunk may swell or shrink daily depending on the flow of nutrients and light; if the season is mild, it may even grow a bit.

Just beyond the trees, team leader Jan Eitel of the University of Idaho installs a sensor to record total radiation reaching the plot—a key factor in plant growth.

Boelman prepares to test a tree’s capacity to use sunlight for photosynthesis. At the height of summer, intense sun shines 24 hours a day.

Remote-sensing specialist Lee Vierling of the University of Idaho takes fluorescence readings from spruce needles. Instruments behind him automatically record temperature, wind speed, air pressure and humidity.

In this environment, everything grows slowly. This seedling only looks like a baby; it is actually 15 or 20 years old.

Boelman and Vierling judged this spruce to be at least 96 years old, meaning it probably took root some time shortly after World War I.

University of Idaho grad student Andy Maguire programs the LiDAR. In cooperation with NASA, the scientists will combine their painstaking ground observations with large-scale satellite imagery to paint a picture of how the north is changing.

The north is home to a surprising diversity of animals. Here, a year-round forest-dwelling gray jay surveys its domain. In summer, vast numbers of migratory birds also come to nest. Some prefer the trees, while others inhabit only the tundra beyond, so changes in either one will have ecological fallout.

The Alaska pipeline has shipped billions of barrels of oil from the oil fields of Prudhoe Bay to the south since the 1970s. The root of global warming is fossil fuel, and this region, the source of so much of it, is warming two to three times faster than the worldwide average.

The oil is starting to run out, but development is proceeding apace. Boelman checks out a fiber-optic cable being laid to Prudhoe Bay. There is now talk of a new pipeline that would carry natural gas instead of the waning oil.

The most visible impact of warming climate on northern forests is increasing wildfire; this stretch along the Dalton Highway burned a couple of years ago. Each summer, huge blazes afflict Alaska, Canada and Russia; some even spread into the tundra, where fires had been previously unknown.

The researchers stayed each night at the decayed early 1900s gold-mining town of Wiseman (though not at this cabin). Wiseman became reachable by road in the 1990s, and now tourists can drive here—another sign that the far north is opening up.

Scott Schoppenhorst, a mechanic, has lived in Wiseman for 30 years. “Call it global warming or what you want–winters are warmer, and everything is growing faster,” he says. Here he is trying to get some grass to grow near his airplane hangar, and he is pretty optimistic it will work.

From the local perspective, the warming trend can be good; the few gardens in Wiseman are certainly benefiting.

Oil and mining are pillars of Alaska’s economy, and most residents support more development. One Wiseman doorway is testimony.

As human influence grows here, scientists hope to better predict how the environment will affect plants, trees, animals, people. A Wiseman fence made of caribou and moose antlers speaks to the powerful intertwining of man and nature in this region.