ABSTRACT
The global C cycle is defined as the exchange of carbon (C) among the atmosphere, seawater, land vegetation, and soil reservoirs. Each year dead plant materials entering the soil are decomposed by soil microbes that return carbon dioxide (CO2) to the atmosphere. If the amount of land vegetation remains the same, the amount of CO2 removed from the atmosphere by plant growth each year is balanced by the amount of plant death and decomposition. Such a perfect balance, however, is seldom seen. Changes in the quantity of C in vegetation and soils play a major role in determining short- and long-term fluctuations in the concentration of CO2 in earth’s atmosphere.
