Feedback Effects of Soil Carbon Cycling in Northern Ecosystems Essay

Feedback Effects of Soil Carbon Cycling in Northern Ecosystems spherical thawing will be greatest in mid-continental North America and Eurasia, where temperatures are predicted to increase 4 - 12_C during the winter and 2 - 6_ C in summer (Kasischke et. al, 1995). This thawing will shift the boreal forest, bog, and tundra biomes that dominate these areas northward as much as 500 km in the first hundred years of warm (Toward...1988, qtd. in Varallyay, 1990). Alaskan studies indicate that these changes are already influencing ecosystem function and cytosine balance in northern ecosystems (Grulke et al. 1990 Ochel and Billings 1992 Oechel et al. 1993 qtd. in Oechel et al. 1995). Alterations in carbon cycling in these soils are of particular concern, since soils of northern ecosystems store from 350-455 Pg of carbon, or from 22.5 to 29.4% of the world soil carbon pool (Billings, 1987 Post, et al., 1990 Oechel and Vourlitis, 1993 qtd. in Lal et al.1995). This sink is an important part of the global carbon cycle soil carbon wantes from changes in land use account for 40% of the increase in atmospheric CO2 to date (Tinker and Ineson 1990). metalworker and Shugart (1993) have projected that the vegetation/soil system will eventually become a carbon sink when global warming occurs. However, the initial loss of soil fundamental matter and delayed response of ecosystems to range shifts are expected to cause an initial pulse of carbon to the atmosphere, representing a temporary overbearing feedback to climate change. The amount of organic carbon stored in the soil depends on the net primary productivity (NPP) of the ecosystem and the speed of humic decomposition. Rates of soil organic matter decay are partially temperature dependent Jenkinson... ...niversity Press, 1995. Smith, T. M. and H. H. Shugart, 1993, The transient response of terrestrial carbon storage to a perturbed climate Nature, 361, pp. 523-526. Stevenson, F. J. Cycles of Soil Carbon, Nitrogen, Phospho rus, Sulfur, Micronutrients. New York, toilet Wiley & Sons, Inc. 1986. Tinker, P. B., and P. Ineson, 1990. Soil organic matter and biology in relation to climate change in Soils on a Warmer Earth, H. W. Scharpenseel, M. Schomaker and A. Ayoub, eds. New York, Elsevier, 1990. Varallyay, G. Y., 1990, Influence of climatic change on soil moisture regime, texture, structure and erosion in Soils on a Warmer Earth, H. W. Scharpenseel, M. Schomaker and A. Ayoub, eds. New York, Elsevier, 1990. Whalen, S. C., W. S. Reeburgh, and K. S. Kizer, 1991. Methane consumption and emission by taiga Global Biogeochemical Cycles, 5(3), pp. 261-273.