ABSTRACT
The current change in the global climate is attributed to the unprecedented concentration in the atmosphere of greenhouse gases (GHGs). The main GHGs are CO2, N2O, CH4, and CFCs. Agricultural activities, including land use and land-use change, constitute an important source of GHG, being responsible for 25 percent of CO2, 50 percent of CH4, and 70 percent of N2O emitted by all human activities (Agriculture and Agri-Food Canada, 1998). At a global level, agricultural activities use approximately 35 percent of all the existing lands on the planet. If the accumulation of GHGs continues at the present rate, experts predict an increase in the average global temperature between 3 and 5°C by the end of the twenty-first century (IPCC, 1996, 2001). Because such increase may have serious consequences for humankind, mitigation measures must be adopted by all nations of the world. One of this mitigation measures is to increase carbon (C) stock in the major components of the ecosystems. Plants and soil are two major compo-
nents of the ecosystems with a high C sequestration potential which merit both basic and adaptive research.
