干旱区生态环境知识资源中心

Estimation of natural isotopic abundances can integrate across biogeochemical processes affecting the carbon and nitrogen dynamics in an ecosystem. Here, we investigated the natural isotopic abundances (delta C-13 and delta N-15) of the soil in healthy and degraded alpine ecosystems, including alpine meadow, alpine steppe, and alpine desert on the Qinghai-Tibetan Plateau (QTP). We also examined the effects of plant factors and soil chemical and physical factors on the soil delta C-13 and delta N-15 in these alpine ecosystems of the QTP. The results indicated that the soil delta C-13 and delta N-15 varied significantly with the grassland type, the land degradation, and soil depth. The C4-plant dominated alpine desert was much higher in the soil delta C-13 and delta N-15 than the C3-plant dominated alpine meadow and alpine steppe. Along the soil depth of 0 to 30 cm, the delta C-13 and delta N-15 were enriched in all types of the alpine ecosystems. The land degradation lowered the plant cover, aboveground plant biomass, soil organic carbon (SOC) and soil total nitrogen (TN) in all alpine ecosystems. Land degradation enriched the soil delta C-13 in the alpine steppe and the soil delta N-15 in alpine desert by changing their interactions with the plant and soil features.