Spatial-temporal Changes of Vegetation Coverage and Topographic Effect in Yunnan Province from 2010 to 2020

Based on MODIS data and dimidiate pixel principal, spatial-temporal distribution dynamics of vegetation coverage in Yunnan province from 2010 to 2020 were obtained by trend analysis method and variation coefficient. Topographic effect on average vegetation coverage was analyzed by with SRTM DEM data. The results showed that the monthly mean vegetation coverage of Yunnan province presented a single-peak distribution, with the lowest in February and the highest in September. The annual mean vegetation coverage increased slightly, 0.003 4/a, and the only decrease was occurred in 2011 due to extreme drought. Yunnan province was dominated by middle and high vegetation coverage, with a spatial pattern of higher coverage in the southwest and lower in the northwest, northeast and central parts. The vegetation coverage increased gradually from north to south and from east to west. The increasing area of vegetation coverage was larger than the decreasing one, indicating that the vegetation coverage in Yunnan province improved. The overall fluctuation is the most severe in the central and eastern regions, followed by the northwest and north, and the most stable in the southwest and south. There was a significant negative correlation between vegetation coverage and elevation and slope, but was not significant with aspect. The area with elevation <1 000 m or slope <15° had the highest vegetation coverage.