Spatio-temporal Variation of NDVI in the Vegetation Growing Season of the Zoige Plateau from 2000 to 2019

Based on the MODIS−NDVI time series data set from 2000 to 2019, this paper uses trend analysis, coefficient of variation, and R/S analysis to reveal the spatio-temporal characteristics of NDVI during the vegetation growing season of the Zoige Plateau. The results show that in the past 20 years the NDVI in the vegetation growing season of 87.45% of the Zoige Plateau showed an improvement, of which 64.70% showed a significant improvement and 22.75% showed a slight improvement. The average coefficient of variation of NDVI in the vegetation growing season is 0.186 5. Overall, the NDVI in the vegetation growing season of the Zoige Plateau from 2000 to 2019 has a moderate fluctuation state. The proportion of the medium change state grade is 33.70%, followed by the proportion of the lower fluctuation grade is 33.14%. The average Hurst index of NDVI in the vegetation growing season was 0.437 2, showing a weak anti-sustained state as a whole, with a weak anti-sustained ratio of 77.43% and a weak sustained ratio of 21.50%.