Feedback Effects of Soil Carbon Cycling in Northern Ecosystems Essay

Feedback Effects of Soil Carbon Cycling in Northern EcosystemsGlobal warming leave alone be greatest in mid-continental North the States 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 warming 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 warming (Toward...1988, qtd. in Varallyay, 1990). Alaskan studies indicate that these changes are already influencing ecosystem bleed and carbon 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 farmings 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 humankind soil carbon pool (Billings, 1987 Post, et al., 1990 Oechel and Vourlitis, 1993 qtd. in Lal et al.1995). This sink is an imp ortant part of the global carbon cycle soil carbon losses from changes in defeat use account for 40% of the increase in atmospheric CO2 to date (Tinker and Ineson 1990). Smith 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 organic matter and delayed response of ecosystems to scarper shifts are expected to cause an initial pulse of carbon to the atmosphere, representing a temporary positive 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 short-lived response of terrestrial carbon storage to a perturbed climate Nature, 361, pp. 523-526. Stevenson, F. J. Cycles of Soil Carbon, Nitrogen, Pho sphorus, Sulfur, Micronutrients. New York, John Wiley & Sons, Inc. 1986. Tinker, P. B., and P. Ineson, 1990. Soil organic matter and biology in apprisal 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 wearing 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.