Effect of Cultivated Pasture on Recovering Soil Nutrient of 'Black-beach' in the Alpine Region of Headwater Areas of Qinghai-Tibetan Plateau, China

Alpine grassland ecosystem of the headwater area of three rivers, Qinghai-Tibet plateau, has been degraded during past decades due to the intensified human activities and climate change. The severely degraded grassland, named “black-beach” has partly been restored with planting the located quality forage and fertilizing in recent years. In this study, we collected soil samples (0-4 depth) from three grasslands at different cultivated ages (cultivation of 4, 7 and 9 years) and one natural grassland at severely degraded level (served as a control) to explore the effect of pasture cultivation on soil nutrients. In addition, the size and the depth of the bare patches in the severely degraded grassland were investigated to estimate cultivated grasslands‟ capability of fixing the soil substances and recovering the soil nutrients. The results showed that the soil nutrient in the cultivated pasture declined at the early stage of cultivation, increased with cultivated ages, i.e., total N, total C, Ca, and P in soils at 0-4 cm depth increased 10-23% after 9 years of cultivation. Pasture cultivations can be regarded as a good strategy to fix the soil surface and recover the soil nutrients of severely degraded grassland on the Qinghai-Tibetan Plateau of China.