Introduction to BOREAS

Along the northern edges of North America, Europe, and Asia—ringing the Arctic Circle—lies an expanse of forest almost unchanged since the end of the last ice age. Extending from 45° to 65° North, these forests are known as the boreal forest in North America, and the taiga in Europe and Asia. Trees such as spruce, pine, aspen, and birch dominate the landscape (which is often covered in snow), struggling through the long, cold winters in shallow soil, roots frozen. Moose, reindeer, and wolves range through these forests, while owls and ravens patrol the skies above. Much of the forest floor is covered in moss, growing in thick layers of peat (dead plant matter that decomposes slowly or not at all.) These layers of organic matter are composed almost entirely of carbon, originally drawn from the air by the respiration of plants. Only a meter or so below the surface the soil is perpetually frozen, stunting plant growth and stabilizing the subsurface temperature.

The world's boreal forest is huge—almost 20 million square kilometers (29 times the size of Texas)—but relatively uninhabited. Earth scientists and climatologists have long known that the boreal forest plays an important role in global climate, but have been hindered in their studies of the region due to the harsh conditions and remote location. The Boreal Ecosystem-Atmosphere Study (BOREAS) was a major international research program sponsored by NASA's Goddard Space Flight Center and carried out in the Canadian boreal forest. It's primary goals were to determine how the boreal forest interacts with the atmosphere (via the transfer of gases and energy), how much carbon is stored in the forest ecosystem, how climate change will affect the forest, and how changes in the forest affects weather and climate. Primarily conducted from 1994–1996 (with some experiments still continuing) BOREAS integrated ground, tower, airborne, and satellite measurements of the interactions between the forest ecosystem and the lower atmosphere. The findings from BOREAS are now being released, and the Earth Observatory presents a series of articles based on the most significant:

The data used in this study are available in one or more of NASA's Earth Science Data Centers.


Although much of the boreal forest is composed of conifers like pine and spruce, deciduous birch and aspen add color to some regions. (Photograph by Andreas Barth,

Aurora Borealis
Displays of the northern lights are common during the long winter nights of the high latitude boreal forests. (Photograph by Jan Curtis, University of Alaska Fairbanks Geophysical Institute)

Gray wolves roam through the wilderness hunting animals such as reindeer, elk, and hares. (Photograph courtesy U.S. Fish and Wildlife Service)

Sunbeams in the forest
Sunlight is one of the most important resources in the boreal forest, where the sun is often low on the horizon. (Photograph by Andreas Barth,

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