| The study of soil carbon cycling is yet not fullest part in the research of carbon cycling in terrestrial ecosystem. It products greater error in predicting soil carbon pool. This is because soil is a asymmetric structure of three-dimension. It shows complex relation in spatial scale and has complex interactions with climate and vegetation and life of terrestrial ecosystem. In the study of soil carbon cycling, especially in the research at regional scale, lots of problems need be solved, even in some methods such that in the turnover rate of soil respiration and fine root in soil there has a coherent and correct method. The model of soil carbon cycling is important in carrying out simulating and predicting soil carbon cycling and is a effect tool synthesizing different factors and their interactions. The paper tries to introduce the Integrated Terrestrial Ecosystem C-budget model(InTEC model), analyzes the structure, modifies its parameters of soil carbon pools and simulates dynamics of soil organic matter in Liping County.Soil sampled including red soil and yellow soil is obtained from Liping County and is covered by different vegetations such as Phyllostostachys pubescens, Cunninghamia lanceolata (8,12,14,60 years), Shrubs, Broadleaf, Camellia Oleifora Abel, Couch grass and Pine trees. Soil dried and sieved is incubated at 25 C, dark condition. The result shows that the trend of turnover rate is similar that the decomposition rate is faster in beginning and then becomes slower. The content of decomposition accounts to percent 37 ~ 41 in seven days of beginning in incubation of 61 days. But decomposition of soil from different vegetation varies with incubation days. The trend of decomposition rate is respectively Shrubs, Broadleaf, Conifer and Phyllostostachys pubescens.Soil organic carbon pool is divided into three pools-active, slow and passive poolaccording to different turnover time. The three pools complies with first-order model CSOC= Ca e-K + Cs e + Cr e. The paper uses acid hydrolysis to measure the size of passive pool which accounts to percent 20-50 of total organic carbon. The size of active and slow pool and the decomposition rate can be fitted by using the first-order model according to dynamics of soil organic carbon and presupposition of the mean residue time.The result shows: the size of active pool from different profiles accounts to percent 0.5-7.6 of total soil organic carbon and the mean residue time is 41-64 days; slow pool, percent 45-71, 3-30 years. The trend of active carbon pool is respectively mixed, deciduous and conifer, slow pool of mixed forest accounts the greater proportion. The maximum decomposition rate of soil active and slow pool from different vegetation is respectively: conifer 7.5 ly-1, 0.36 y-1; deciduous 8.23 y-1, 0.13 y-1; mixed 8.87 y-1 , 0.33 y-1 according to the equation of the maximum decomposition rate in the model. The fitted value modifies corresponding parameters in the model.The model simulates soil organic carbon density of different profiles using the data of remote sensing, climate and soil resources of 1 kilometer resolve. The validation result shows that simulative value is close to the real value (R2=0.6706). Therefore, Integrated Forest Ecosystem C-budget model can simulates soil organic carbon density from different profiles in Liping County. To further validate its applicability at greater temporal and spatial scale, parameters need be modified in the model and somenew effect factors can be added combining base date-map of high precision and standardization with some representative forest soil of different climate type.
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