Abstract: Wetlands are an important reservoir of soil organic carbon and provide an important guarantee for maintaining global carbon dioxide balance. In this study, we collected soil samples at different depths of different vegetation types (wetland vegetation and grassland) from alpine wetland in Zoige, to analyze the horizontal and vertical variation characteristics of soil organic carbon. We found two different characteristics of the vertical distribution of soil organic carbon. First, the content and density of soil organic carbon decreased significantly with increasing soil depth, with the difference between maximum and minimum values being 20.03 times and 7.47 times, respectively. Second, the content and density of soil organic carbon fluctuated with increasing soil depth, and maintained a high level in deep layer, with the difference between the highest and lowest values being only 2.90 times and 1.48 times. The horizontal distribution of soil organic carbon content and density in Zoige alpine wetland showed obvious spatial heterogeneity. The content and density of soil organic carbon in wetland soil were significantly higher than that in grassland, and both characteristics of the samples with high soil moisture content were significantly higher than those with low soil moisture content. In conclusion, the Zoige alpine wetland soil has a strong carbon sequestration capacity, with high soil water content being an important prerequisite for maintaining soil carbon sequestration function of Zoige alpine wetland. Our results are of great significance to the ecological environment management and sustainable development of alpine wetland.

Key words: Zoige wetland, organic carbon content, organic carbon density, horizontal distribution, vertical distribution.