[Study on soil organic carbon pools and turnover characteristics along an elevation gradient in Qilian Mountain]

On the basis of the first order dynamic model combining with the laboratory soil incubation experiment, characteristics of soil organic carbon pools(Csoc), active carbon pools(Ca), slow carbon pools(Cs), passive carbon pools(Cr) and their turnover in Qilian Mountain were studied. It has been showed that the size of Csoc in horizon A and B ranges from 7.606- 89.026 g.kg - and 5.804-84.267 g.kg-1, which shows tendency of "increase-decrease-increase-decrease" with elevation. The size of Cs, Cs, and Cr in horizon A and B under different elevations respectively ranges from 0.180-1.328 g.kg-1, 0.159-1.273 g.kg-1; 3.650-35.173 g.kg-1, 3.703-43. 623 g.kg-1; 3.776-65.298 g.kg-1, 1.942-48. 121 g.kg-1, which incarnates no obvious variation law with elevation. The contents of Csoc, Cr and Cs significantly differ with different elevation gradients. There is no significant difference in the C, content between different elevation gradients. Decomposition rate of Csoc also has no evident change law in elevation. The peak of daily carbon release rate varies with carbon release rate in the whole incubation process, which could be used to present character of SOC turnover rate. It has been also showed that Caand peak of daily carbon release rate have a significant relationship, and they follow the linear relationship. The incubation reveals that Csoc turns over in sequence of Ca, Cs, and Cr,. Polynomial equation presents relation between total SOC release amount and time, of which cubic polynomial has achieved preferable precision(R2 >0.99).