The difference in soil organic carbon distribution between natural and planted forests: A case study on stony soils mountainous area in the Upper Min River Arid Valley, China

Abstract

Few studies have been conducted on the factors and distribution of soil organic carbon (SOC) in plantation forests in arid mountainous regions, especially in orchards. We aimed to unravel the SOC distribution among land‐use types and the effects of altitude gradients and rock fragment content (RFC) on SOC accumulation and sequestration in the Upper Min River Arid Valley, China. The differences in SOC distribution among land‐use types were quantified. The correlation analysis of SOC with various factors, such as altitude and RFC, was conducted. The variation percentage in SOC content and stocks was explained by the factors' contribution using mixed‐effects models. SOC distribution was characterized by high content and low stocks in native forests and shrubs, high content and high stocks in eco‐forest, and low content and high stocks in orchards. At the surface (0–30 cm), SOC content and stocks in orchards (cherry, plum, and apple) were significantly lower than those in eco‐forests. There was a significant positive correlation between altitude and SOC content at the surface but not at the subsoil (30–60 cm). With RFC increased, the surface SOC content decreased in native forests, shrubs, and eco‐forests, while it increased in orchards. Our results suggest that land management is the main factor controlling the variation in SOC distribution. Enhancing the surface SOC stability in orchards by land management is a priority for soil carbon pool management in the Arid Valleys.

Carbon Distribution Characteristics and Sequestration Potential of Various Land-Use Types in a Stony Soil Zone of the Arid Mountainous Regions on the Eastern Tibetan Plateau

“…So, what is the range of the appropriate amount of soil gravel? Wang et al [48] found the highest SOC stocks under 40-50% gravel cover in the cold and arid desert of the Northwest Tibetan Plateau; Han et al [49] found that rock fragment contents (5-55%) in orchards positively correlated with SOC contents in dry valleys in western Sichuan, China. Farmers in this region varied widely in their understanding of the appropriate range of soil gravels (soil in some orchards contained 36.8% gravel, while others contained only 11.8%; see Table 1).…”