Alpine grassland degradation in the Qilian Mountains, China — A case study in Damaying Grassland

Abstract

Degradation of semiarid grassland and efforts to control that degradation have become pressing issues. However, the inherent characteristics of the grassland and the intertemporal nature of the problem complicate the analysis of degradation issues, and consequently, the search for more appropriate rangeland policies. Using the Damaying Grassland as a case study, we assessed alpine grassland on the north slopes of the Qilian Mountains by means of in situ samples using vegetative cover, biological diversity, forage productivity, soil bulk density, and soil nutrients as the main evaluation indices. The forage yields on high, moderate, and low coverage rangeland exhibited decreases of 20.2%, 20.8% and 56.4%, respectively, from 1982 to 2012. Due to the lower basal cover of rangeland in poor condition, soil nutrient and organic matter content decreased with rangeland degradation. Increased soil compaction appears to lead to lower basal cover of rangeland The soil bulk density in high, moderate, and low coverage rangelands was found to be 0.8g·cm−3, 1.1g·cm−3, and 1.2g·cm−3, respectively. The soil nutrient levels and organic matter contents indicate that the rangelands experienced degradation over the 30-year period. Organic matter and available nitrogen decreased significantly over time, while available phosphorus and available potassium increased significantly. Overall, our results show that the Damaying Grassland is in a period of rapid degradation, and that mitigation and remediation measures are needed to protect the rangelands.