Abstract:

A widely used model, Century, was used to simulate the seasonal dynamics of carbon fluxes from soil microbe respiration in alpine Kobresia humilis meadow at Haibei research station, CAS. Monthly maximum and minimum air temperatures and precipitation derived from meteorological data at Menyuan weather station in Qinghai province were used to drive the model. Carbon, nitrogen and cellulose contents were used to initialize the Century model, and all parameters related to the model were based on data from published documents. The observed versus simulated CO₂-C efflux gave R²＝0.89 (P＜0.05) with all months included in the analysis. The 0 to 20 cm SOC level at equilibrium was about 7,597.50-7,694.10 g C/m², with the active, slow and passive SOC pool sizes about 2.80%, 58.50% and 38.70% of the total SOC, respectively. The following simulation resulted in stable fluctuation change in SOC, which was mainly caused by fluctuations of its fractions. The impacts of climate changes on soil SOC was mainly related to soil passive SOC, and a negative correlation existed between mean annual air temperature and passive SOC pool size, with the partial correlation coefficient of -0.548 (P＜0.01). Precipitations had no effects on SOC or its fractions over the entire simulation period of about 45 years.