Changes in different grassland types and their vegetation coverage in northern Shaanxi Province during 2000-2010

We investigated variability of vegetation coverage across different grassland types in key years (2000-2010) of major ecological construction projects in northern Shaanxi Province. Products of ecosystem classification and ecological parameter data were utilized to systematically elaborate succession processes, combined with several evaluation indexes, including inter-annual variation coefficient, trending slope, and degradation index. Our results showed that:(1) There was an obvious increase in area of grassland ecosystem in the loess gully region in Yanan and Yulin City with annual average vegetation coverage from 27.94% in 2000 to 40.50% in 2010. Grassland coverage increased from a low to moderate level, accompanied with a significant uptrend in temperate steppe and warm-temperate tussock coverage. (2) Most of the grassland coverage in the northern Shaanxi regions changed obviously (increasing grassland accounted for 93.98%). The grassland ecosystem showed relatively significant fluctuations in the north of Yanhe River, but remained relatively steady in the south of the river. The significant increase in grassland vegetation coverage was mainly in the hilly loess regions, with the main decrease area located in the temperate desert steppe region of the northwest of Yulin. (3) Over the 11 years, the degree of severe degradation of grassland has been reversed in northern Shaanxi (from 9594.44 km² during 2000-2005 to 26 544.39 km² during 2005-2010). This study suggests that grassland coverage across different grassland types in northern Shaanxi have improved to varying degrees.