Ecosystem Studies & Management
Boreal Forest & Arctic Tundra Dynamics
The Boreal Forest Ecosystem
A mature spruce stand near Delta Junction, Alaska
The circumpolar boreal forest is an integral part of the global ecosystem and has important influences on the global cycling of energy, carbon and water. Over the past 30 years, global boreal forests have experienced a significant amount of warming and drying which, if trends continue as predicted, are likely to induce feedbacks that may further influence global climate.
The goal of the Woods Hole Research Center’s work in this region is to quantify the magnitude and variability of carbon exchange, assess the mechanisms by which fire disturbance influences these processes, and characterize how changes in these ecosystems respond to and are influencing climate. By synthesizing results from direct field measurements, satellite remote sensing and ecosystem modeling, Center scientists study the processes driving changes in the boreal forest in order to inform assessments and predictions of how those changes will be expressed under a future climate regime.
Scientists at the Woods Hole Research Center are contributing to understanding the changing Arctic, and how these changes will influence the global climate system. WHRC projects are studying arctic tundra and boreal forests in Russia and North America, with the objective of learning how climate change is altering carbon storage in these globally important ecosystems, and understanding how these changes feedback on climate. Center researchers also are studying the largest arctic rivers in Russia, Canada, and Alaska, working to understand how increasing river discharge driven by global warming will influence ocean circulation and climate over the coming century. Much work remains to be done, but the Woods Hole Research Center is committed to improving the scientific understanding of the Arctic in order to better inform policy makers and the public as they make decisions impacting the Arctic and the global climate system.
The Importance of Boreal Forests
Coverage of Boreal Forests
MODIS Tree Cover data displaying the forests of North America and Eurasia. Percent tree cover increases as colors become darker.
Boreal forests and woodlands cover approximately 14.5% of the earth's land surface, comprising an area of nearly 16 million square kilometers (5.7 million square miles) – or about the size of the conterminous United States. The boreal region forms a circumpolar band throughout the northern hemisphere, extending through Russia, Northern Europe, Canada, and Alaska (see image, right). The southern limit of the boreal forest biome is not a distinctly defined boundary, but generally varies between 50° and 60°N latitude, although in Siberia it dips as far south as 45°N. The North American boreal region makes up approximately one third of the global boreal biome, and thus constitutes a significant component of the boreal carbon pool.
Carbon Storage in Boreal Forests
The boreal region covers just under 15% of the global land surface, but contains over 30% of all carbon contained in the terrestrial biome. This is largely due to the disproportionate amount of carbon held in boreal soils compared to other forest biomes. In general, the amount of carbon stored in forest soils is controlled by the rate of supply and release of carbon. Carbon is supplied to the soil through litterfall, fallen woody debris, and root mortality. This detritus is subsequently decomposed through various microbial pathways and the carbon is released to the atmosphere.
Comparison of Carbon Storage in Boreal, Temperate, and Tropical Forests
|Biome||Area (x 106 ha)||Soil Carbon (Pg)||Plant Biomass Carbon (Pg)||Total Carbon (Pg)|
|Based on Kasischke, 2000
(One Pg [petagram]=one billion metric tonnes or one trillion kg)
In boreal regions, extremely low temperatures promote the formation of cold and frozen soils called permafrost. The cold temperatures within these soils reduce decomposition rates, thereby leading to the development of deep organic soils that may be hundreds of years old. These cold, often saturated or frozen organic soils release relatively little CO2 to the atmosphere through microbial respiration, although large amounts may be rapidly released by increasingly frequent forest fires, which also generate deep soil thawing once the insulating blanket of moss and peat is removed.
View "Bio Bulletin: The Ecology of Climate Change" video here.
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