| It is generally accepted that karst ecosystem controlled by geology is fragile. This is the result of soluble rock dissolution, which brings about shortage in soil and water on the surface. So karst vegetation is charactered by Petrophile, Xerophile and Calciphihe in those areas where soil cover is very thin, and the underground drainage system is well developed. The running of karst ecosystem is controlled by two subsystems, which are karst dynamic system in inorganic life and genetic information transmitting system in organic life. But it is mainly drived by the karst dynamic system centered on the cycle of CO2-water-calcium. As one part of karst ecosystem, epikarst ecosystem is composed of rock, water, vegetation, soil, and atmosphere. It is sensitive to the global carbon cycle in Quaternary, especially in late Holocene. As a hard-core part of epikarst ecosystem, soil makes a hinge action in the karst process. It forms a leach layer between rainfalls and carbonate and gives a great much time and space in the karst process. Soil CO2, a very pivotal factor in the karst dynamic factors, makes an action of driving forces in karst dynamic system. New achievements having been obtained in this field show that CO2 participating in karst process in the epikarst dynamic system mainly comes from soil air CO2 created by the organic carbon, in other words, although karst is a kind of biochemistric action in nature, distribution and transmit and cycle of carbon rely on changes of soil organic carbon. Soil organic carbon is the greatest carbon storeroom. Soil respiration emission of CO2 is the most important passing entrance in carbon cycle of epikarst ecosystem. So it is chiefly that soil CO2 concentration and its influencing factors should be studied in ordered to learn the mechanism of epikarst ecosystem and global carbon cycle.Karst Dynamics laboratory, Ministry of land and resources, has been studied the mechanism of seven typical epikarst ecosystem and global changes through IGCP 299(Geology, Climate, Hydrology and karst Formation, 1990-1994) and IGCP 379(Karst Processes and the Carbon Cycle, 1995-1999) to IGCP 448(World Correlation of Karst Ecosystem, 2000-2004), while observation and analysis and research of epikarst ecosystem in Mt.jinfo have just been beginning. The thesis analyzes that based-on observational point of green pond and deep dell in the west slope of jinfo mountain, CO2 concentration and regularity of epikarst ecosystem contrasting woodland with uncovered land have been studied through the observation of temperature and humidity and CO2 concentration. The main results are as follows:1 .Soil CO2 concentration of epikarst ecosystem begins to increase in turn with the depth of soil, and it is mainly controlled by temperature and humidity without rain.2.The range of soil CO2 concentration varied with soil temperature is not the same for the soil layer and its characters and different vegetation: the varied range of topsoil is higher than that of deep soil at testing woodland; the varied range of soil layer (-20cm) is the highest than that of the other soil layers; the range of CO2 concentration varied with air temperature begins to increase in turn from woodslay and shrublay to herbage.3.It is clear that CO2 concentration of epikarst ecosystem has been influenced for rain. The varied range of soil CO2 concentration is mainly influenced by rain frequency, secondly the amount of rainfall for the epikarst ecosystem of woodland and uncovered land. The varied range of CO2 concentrations in vegetation air system are mainly influenced by the amount of rainfall, secondly the rain frequency.4.Soil respiration emission of CO2 at testing woodland and uncovered land changes sensitively with the three factors, such as soil temperature, vegetation and humidity. But it is mainly controlled by soil temperature, secondly humidity and vegetation.
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