关键词: 草地退化, 敏感性, 社会经济驱动力, 载畜量, 植被类型, 锡林河流域

Abstract:

Aims Overgrazing is a key factor driving grassland degradation in arid and semiarid regions. In this study, we explored how spatial and temporal patterns of grassland degradation were linked to vegetation sensitivity and socioeconomic drivers in the Xilin River Basin, Inner Mongolia, China.

Methods We categorized grassland degradation by species composition and community characteristics by comparing a 1980’s vegetation map with data from field surveys done in 1984 and 2004 across the Xilin River Basin. Five types of grasslands were distinguished: non-degraded, slightly degraded, moderately degraded, heavily degraded, and extremely degraded. We also classified two additional types of grasslands based on their conditions 20 years ago: salinized and restored grasslands.

Important findings The distribution of degraded grasslands exhibited an obvious spatial pattern across the Xilin River Basin. In general, the degree of grassland degradation increased from upstream in the southeast to downstream in the northwest of the basin. Moderately degraded grasslands were distributed mostly in the southeast, and heavily degraded and salinized grasslands were located in areas close to the river and over much of the Hunshandak sandland. Extremely degraded grasslands were distributed throughout the northern part of the basin where ecosystems were more vulnerable to over grazing. Non-degraded and slightly degraded grasslands were scattered patchily across the basin. In contrast, some abandoned farmlands and fenced pastures rested from grazing showed restoration over the past two decades. Grassland degradation in the basin also showed vegetation-type specific characteristics. About 43% of the shrubland was slightly degraded. More than 50% of Festuca ovina and Ulmus pumila dominated grasslands were moderately degraded, and half of the Stipa baicalensis and Bromus inermis dominated grasslands were heavily degraded. For both Stipa krylovii and Caragana microphylla dominated grasslands, more than 50% of the total areas were extremely degraded. For Leymus chinensis grassland, only small part of the total area had been degraded. Based on our analysis, overgrazing is the most important socioeconomic factor driving grassland degradation in the Xilin River Basin. The grassland degradation was positively correlated with increasing stocking rate from the 1970’s to 2004. Other factors, such as shifts in the density of villages and network of roads, were also attributed to the widespread grassland degradation in the Xilin River Basin.

Key words: grassland degradation, sensitivity, socioeconomic drivers, stocking rate, vegetation type, Xilin River Basin