Influence of Vegetation Coverage and Climate Environment on Soil Organic Carbon in the Qilian Mountains

Abstract

Studying the spatial distribution pattern of soil organic carbon and its influencing factors is essential for understanding the carbon cycle in terrestrial ecosystems. Soil samples from four active layers of typical vegetation types (Populus, subalpine shrubs, Picea crassifolia Kom, and alpine meadow) in the upper reaches of Shiyang River basin in the Qilian Mountains were collected to determine the soil organic carbon content and physicochemical properties. The results show the following: (1) There are significant differences in the vertical distribution of Soil organic carbon in the watershed, and the Soil organic carbon content decreases significantly with increasing soil depth. (2) Mainly affected by biomass, the organic carbon content of different vegetation types in different soil layers is as follows: Alpine meadow > Picea crassifolia Kom > Populus > Subalpine shrub, and the soil organic carbon content increases with increasing altitude. Under different vegetation types, the Soil organic content is the highest in the 0–30 cm soil profile, and the maximum value often appears in the 0–10 cm layer, then gradually decreases downward. (3) When soil organic carbon is determined in different vegetation types in the study area, the change of hydrothermal factors has little effect on soil organic carbon content in the short term.

Dissolved organic carbon transport in the Qilian mountainous areas of China

“…Taking the Xiying River Basin as an example, seasonal frozen soil is generally developed in the upstream river source area, and alpine meadow is a typical vegetation type in the frozen soil area. In addition, Wan et al's study on SOC concentration in the Xiying River Basin showed that the SOC concentration was the highest under the alpine meadow planting in the upstream permafrost area (Wan et al, 2019), which corresponds to the river documented concentration at the sampling point (M4) in the river source area of this study.…”

“…In this study, it was found that there is a significant positive correlation between the organic carbon content of the river basin and the DOC concentration of the river (Figure 6). In other words, rivers that flow through areas with higher SOC density usually have higher DOC concentra- Basin showed that the SOC concentration was the highest under the alpine meadow planting in the upstream permafrost area (Wan et al, 2019), which corresponds to the river documented concentration at the sampling point (M4) in the river source area of this study.…”

“…In this study, the upper reaches of the watershed are the alpine meadow soil, which has a large SOC pool (Wan et al, 2019). In alpine meadow soil rich in carbon pools, river erosion causes the meadow soil to collapse, causing SOC to dissolve in rivers, thereby increasing DOC production in upstream rivers (Meyer & Tate, 1983).…”

“…These soil samples were air-dried, and gravel as well as roots were removed by a 2 mm sieve. Additionally, soil organic carbon (SOC) concentrations were determined by wet oxidation with dichromate (Wan et al, 2019).…”

“…The ecological environment of the Shiyang River Basin is fragile. Current research on organic carbon in this basin mainly focuses on farmland‐soil organic carbon in the middle and lower oasis areas (Shi et al, 2010), the content of soil organic carbon in the upper mountainous area (Wan et al, 2019), and the impact of returning farmland to forests on soil organic carbon (Shurong et al, 2018). However, a few studies have been performed on the characteristics and influencing factors of the DOC in the upper mountain rivers as well as the interaction of soil organic carbon and water organic carbon in high mountain basins.…”