Analysis of the spatio-temporal patterns of vegetation fractional coverage in the Hexi arid area

Taking grassland vegetation as the research object, we examined the applicability of three types of existing vegetation fractional coverage estimation method in arid areas based on long-time series MODIS and field measured data in the Hexi arid area. To this end, we analyzed the spatio-temporal dynamics of grassland vegetation fractional coverage in the test area from 2001 to 2015. The results indicated that an empirical model between the index TVI and vegetation fractional coverage had the highest precision, and is thus considered suitable for estimating the vegetation fractional coverage in the study area. The spatial distributions of the maximum vegetation coverage of grassland were significantly different, and the vegetation coverage decreased gradually from southeast to northwest. Overall, there was an extremely significant increase in vegetation coverage during the period from 2001 to 2015, albeit with spatial heterogeneity (P < 0.01). Restored areas were mainly concentrated in the central and western regions of the Hexi arid area, whereas degraded areas were scattered in the northern part of Mazong Mountain, the western region of the Shiyang River basin, and the east section of the Qilian Mountains.