Changes in Soil Physical and Chemical Properties During the Process of Alpine Meadow Degradation along the Eastern Qinghai-Tibet Plateau

Soil moisture, nutrients and environmental conditions have extremely vital effects on vegetation growth and microbial activities in terrestrial ecosystems. To study the changes of soil physical and chemical properties as affected by degradation along the eastern margin of the Tibetan Plateau, using the largest wetland in Ruoergai as the research sample for two consecutive years, we tested the soil bulk density, the soil moisture content, the pH value, the content of organic C, total N and total P of 0~20 cm and 20~40 cm in different degradation degree (light, moderate, serious and non-degraded alpine meadow). The results show that: (1) Degradation had profound effects on the soil physical properties and chemical properties. with the intensification of the alpine meadow degradation in the eastern margin of the Qinghai-Tibet Plateau, the soil organic carbon, total nitrogen, total phosphorus and soil water content decreased significantly but soil bulk density increased significantly. (2) the soil organic carbon, total nitrogen, total phosphorus contents and soil water content increased with the increase of soil depth, however, the soil bulk density show the opposite regular. (3) The correlation analysis indicated that there was an extremely significant positive correlation between soil organic carbon and total nitrogen, total phosphorus, soil water, and the correlation coefficients were 0.822, 0.907 and 0.885 respectively (P < 0.01). There was an extremely significant positive relationship between the pH and the soil bulk density (r = 0.488, p < 0.01), while a significant negative relationship between pH and soil water (r = –0.387, p < 0.05). Overall, these results suggested that soil degradation not only changed the soil physical properties but also affected the soil chemical properties indirectly. Protecting surface vegetation and reducing wind erosion could be a good way to curb degradation.