Along the northern edges of North America, Europe, and Asiaringing the Arctic Circlelies 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 hugealmost 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 19941996 (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: