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Arctic Dawn

Photo by Richard Jagels

Arctic Dawn
Fossil forest yields clues to a polar swamp

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Axel Heiberg, a desert island in the Canadian Arctic, is an unlikely place for a lush forest. From Cape Stallworthy, its northernmost point, you can see the Arctic ice pack stretching toward the North Pole and beyond. Over the horizon, the next landfall would be Siberia. The island, which is about half the size of Maine, is shrouded in four months of winter darkness, ice and snow, but summer brings 24-hour-a-day sunlight and enough warmth to expose brown hills and river valleys that drain streams off the island's year-round ice cap.

Summer also reveals the remains of an ancient forest multiple layers of stumps, bark, cones, leaves and even logs squeezed tightly into the soil of exposed hillsides. Discovered by a helicopter pilot in 1985 and extending across more than 38 square miles, these forest remnants have since been studied by scientists from Canada and U.S. Unlike the petrified forests of Arizona in which wood is literally turned to stone, this debris was "mummified," buried by floods and then, as the climate changed, preserved for millennia by cold and arid conditions.

The wood is so well preserved that tree rings can be counted; when dried, the wood burns a true fossil fuel. Scientists at the University of Saskatchewan and the Geological Survey of Canada began analyzing fossil remains in the late 1980s. A team from the United States, including University of Maine forest biologist Richard Jagels, visited the island in 1999 and 2000. Carleton University in Ontario, Canada, hosts an illustrated Web site ( on what is described as "one of the best fossil forests in the world."

Meanwhile, fossils continue to emerge from the soil as persistent Arctic winds peel black bits of wood, bark and seed cones out of the earth, and scatter them across the land. Skiers who have trekked across the island report being slowed by wood stuck to the bottoms of their skis.

Scientists have determined that the forest lived about 45 million years ago during the Eocene geological age. The fossils speak of far warmer times, hotter even than what have been projected for the Arctic in the next century as a result of rising global temperatures. Today, low-growing sedges and arctic willow briefly poke their heads above the soil; years ago, the predecessors of 100-foot dawn redwoods and broad-leafed trees shared the landscape with prehistoric crocodiles, rhinoceros and birds.

Now those types of trees live in warm, temperate regions of the world. Just how warm it was, and how plants and animals responded to the combination of warmth and seasonal light extremes, is the focus of ongoing research and scientific debate.

At UMaine, researchers are studying one species of fossil tree, a relative of the modern dawn redwood or Metasequoia, that was dominant until the planet gradually cooled over millions of years. Dawn redwood fossils have turned up across the northern hemisphere in Greenland, Asia, Europe and North America. Scientists thought the species was extinct in modern times until living specimens were discovered in south-central China in the mid-1940s. Jagels will tell you that, although the conditions in which this species thrived no longer exist anywhere on the planet, dawn redwoods could play a role in our future.

A specialist in both forest biology and wood science, Jagels traveled to Axel Heiberg with a research team led by University of Pennsylvania scientist Arthur Johnson. Jagels and his students are studying the ancient material, as well as live dawn redwood trees, to understand how the species thrived in the Eocene and what stresses it might have encountered.

"What interests me most is the physiology and ecology of this forest. How did these trees grow in a regime of continuous light? During May, June and July, the sun never sets, although it shines weakly at a low angle. The whole tree received direct sunlight at some time as the sun circled above the horizon," says Jagels, a professor in the Department of Forest Ecosystem Science, whose research has been supported by grants from the Andrew W. Mellon Foundation and the Maine Agricultural and Forest Experiment Station.

Continuous light presents a problem for trees. "Without a dark period, a tree doesn't have the opportunity to recharge the sap wood" with water and nutrients, says Jagels. In addition, the products of photosynthesis can build up in leaves and halt or reduce photosynthesis itself.

In experiments with dawn redwood seedlings, Jagels, UMaine associate scientist Michael Day and postdoctoral research associate Alejandra Equiza have found evidence that the tree responds to continuous light by rapidly funneling sugars to growing stems and needles. Continuous growth and an expanding crown literally give the dawn redwood a branch up on the competition. Its primary competitor on Axel Heiberg was the larch or tamarack (Larix species), another conifer that loses its needles in winter. In contrast to tamarack, dawn redwood produces more needles and branches that effectively shade out the competition.

Another factor in the dawn redwood's favor is its ability to conduct photosynthesis in the dim light of an Arctic spring or fall. Working with Jagels, UMaine graduate student Xiaochun Li analyzed cells at the surface of dawn redwood needles. Putting the needles under an electron microscope, she found that they contain chloroplasts photosynthetic machinery located well below the surface in most other trees. Like an owl's eye designed to function at night, the position of these chloroplasts makes the tree more sensitive to available light. Together with a convex cell shape that helps to concentrate light, chloroplasts at the needle surface enable dawn redwoods to conduct photosynthesis at a high rate, even when the sun is low on the horizon.

In comparison to modern dawn redwood trees, Jagels' studies of annual growth rings in ancient wood have revealed that the trees on Axel Heiberg appeared to be as productive as their modern counterparts. In fact, dawn redwood prefers wet locations (its Chinese name, shui-sa, means "water fir"), and in the warm, damp paleo-Arctic, it took advantage of swampy conditions.

Jagels and his colleagues have yet to fully understand the whole dawn redwood story, why it lost its dominance and could not compete with other species in places with a regular day and night cycle. But their work suggests that as the Earth got cooler and drier, dawn redwood had difficulty competing with newly evolving species better adapted to changing environments.

Some other conifers, says Jagels, including bald cypress and the towering redwoods of California, appear to be headed toward a status as relicts of earlier ages, hanging on in places that are marginal for other species. As a wood scientist, Jagels would like to harness dawn redwood for a useful role in industrial forestry. In a 2003 article in WoodenBoat magazine (for which he writes a regular column), he suggested that the species has growth and wood properties that make it ideal for tree plantations.

Fast growth (up to 6 feet annually), preference for growing with its own kind and ability to do well on low-nutrient, acidic soils enable it to produce fiber at competitive costs for wood product industries, Jagels argues. Moreover, the wood's moderate rot resistance and light weight make it useful for new wood composite materials in boat building and construction industries.

"Dawn redwood will not be the panacea to fulfill all our future wood needs," he wrote in 2003, "but I am going to predict that it could become the radiata pine (currently the most common plantation tree in the world) of the late 21st century."

Jagels' suggestion has drawn criticism from people who warn of spreading non-native species in the name of commerce. For example, eucalyptus, a native of Australia, has raised concerns on the U.S. West Coast, as has Norway maple in the East. Both have shown an ability to spread and to outcompete native vegetation. But Jagels notes that dawn redwood was widely distributed across the globe before it succumbed to a cooler, drier climate. He stresses that in nearly 50 years of cultivation, it has not escaped from gardens and other developed landscapes. It also is important, he adds, to maintain natural preserves of indigenous species outside of plantations.

Ultimately, saving the genetic stock of relict species, such as dawn redwood, provides resilience in the face of global change. "That's an important goal for me and my colleagues. The Earth will continue changing, and dawn redwood may once again live in high-latitude forests. Black spruce and other species that dominate in northern boreal forests do better in cold climates, but in the distant future, those trees may be restricted to higher elevations," says Jagels.

by Nick Houtman
March-April, 2005

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