Changes in Soil Organic Carbon Content Under Different Inundation Gradients in Peat Bogs on the China's Qinghai-Tibet Plateau

Abstract

The partitioning patterns and retention turnover of soil organic carbon (SOC) in peat bogs are closely related to vegetation, hydrology and soil factors. Research on SOC partitioning patterns in peat bogs in alpine regions in relation to vegetation and soil factors can contribute to the understanding of carbon sequestration mechanisms in peat bogs. In this paper, the Gahai Wetland of international importance on the Qinghai-Tibet Plateau was selected as the experimental site. Three inundation gradient sample plots, SI (heavily inundated zone), SII (moderately inundated zone) and SIII (lightly inundated zone), were established along the vertical shoreline of the lake as the starting point to study the distribution characteristics of the SOC content of peat bogs at different profile depths. The results showed that, horizontally, the SOC content in the three inundation gradients were as follows: SI > SII > SIII, vertically, the SOC content was the highest in the surface layer and showed a decreasing trend from the surface layer to the deep layer with increasing soil depth. All soil factors except bulk density and pH showed a decreasing trend and were significantly different (P < 0.05). The results of the path analysis showed that the effect on SOC content was in the order of soil water content > alkaline nitrogen > total nitrogen > bulk weight, indicating that these four soil factors were the dominant factors affecting the variation in SOC content, their combined effect also played a major role in regulating the SOC content (P < 0.01).