Soil Organic Carbon Storage And The Influencing Factors In The Typical Grassland Ecosystem In China

The study area of the typical alpine and temperate grassland ecosystem in Maduocounty and central-north areas of Inner Mongolia. In this paper, soil organic carbondistribution, storage and influencing fators have been studied by outside data, themain results are brought forth as follows.1. The spatial distribution maps of soil organic carbon density of the alpine andtemperate grasslands in the study area was produced. Soil organic carbon density inthe Southwest and northeast of Maduo County is higer than the Central areas. Soilorganic carbon density in0-20cm of Maduo County between1.03and11.59kg/m2,and the average is3.8kg/m2.The Soil organic carbon density Is progressively reducedfrom north to south and from east to west in North-central region of Inner Mongolia.Soil organic carbon density in0-20cm of the northeast Inner Mongolia is between0.07and20.88kg/m2, and the average is2.36kg/m2.2. It was shown that, based on the soil type, the alpine grassland topsoil organiccarbon stocks of Maduo County is91.44Tg and temperate grassland topsoil organiccarbon reserves is1.662Pg. The results show that based on the vegetation type, Thealpine grassland topsoil organic carbon reserves of Maduo County is101.22Tg andThe topsoil organic carbon reserves of temperate grassland is1.601Pg. Thevegetation carbon reserves of Maduo County are20.341Tg.3. Soil organic carbon density uneven spatial distribution closely related toclimatic factors. Grassland soil organic carbon density have a positive correlation withlatitude and longitude.In the study area, soil organic carbon density have a negativecorrelation with temperature and have a positive correlation with rainfall. The soilphysicochemical characerters also affect soil organic carbon density, which ispositively correlated with soil bulk density, and negatively correlated with Al/Si andC/N. The affect of altitude on soil organic carbon in the alpine and temperategrasslands isopposite.4. When the altitude increased, the alpine biomass ratio first increased and then decreased. Below-ground biomass ratio has a trend of decreasing with mean annualprecipitation(MAP), but increasing with mean annual temperature(MAT).Above-ground biomass ratio has a trend of decreasing with mean annualprecipitation(MAP).5. It is estimated that the mean annual temperature(MAT) will increase by0.4with mean annual precipitation(MAP) increasing by13.28mm after ten years inMaduo, Qinghai province. Under this condition, this study predicts that the soilorganic carbon density will reduce by an average of0.2908kg/m2with the carbonstorage releasing by5.78Tg. The2007annual report of IPCC forecasts the meantemperature will increase by4with precipitation increasing by34mm incentral-north areas of Inner Mongolia by the end of this century. This results wouldlead to the reduction of the soil organic carbon density by1.352kg/m2with therelease of carbon storage by951.32Tg.