Grassland vegetation dynamics over the years based on remote sensing technology in Gannan pastoral area

The monitoring of grassland vegetation based on remote sensing technology is an import branch and hotspot in regional vegetation change research. In order to precisely monitor grassland vegetation dynamic in Gannan, the present study monitors the dynamic change of Gannan grassland over 12 years from 2001 to 2012 and also uses the Perpendicular Vegetation Index (PVI) to explore its applicability and accuracy in grassland monitoring of Gannan. These studies will provide references for livestock production and ecological protection in Gannan pastoral area. The results show that the Dimidiate pixel model based on normalized difference vegetation index(NDVI) can more accurately simulate the vegetation coverage change with a precision of 88.14%. The vegetation coverage results show that the vegetation coverage is maximum at 76.63% in 2010 and minimum at 73.21% in 2002 during the studied period. There is very little interannual variation in vegetation coverage with a variation coefficient of 1.25%. The average grassland area in these 12 years accounts for about 85.47% of the total land area in Gannan with little interannual variation. The Exponential function of PVI can more accurately simulate aboveground biomass in Gannan pastoral area with a mean precision of the monitoring models at 70.48%.