MODIS хиймэл дагуулын NDVI мэдээг ашиглан ургамал нөмрөгийн өөрчлөлтийг үнэлэх нь: Говьсүмбэр аймгийн Баянтал сумын жишээн дээр. (Mongolian)

Assessing changes in vegetation cover using time-series MODIS NDVI data: A case study of Bayantal soum in Govisumber Province. (English)

Determining the pattern of changes in vegetation cover is vital for understanding the environmental change and its influencing factors, as well as for planning and implementing optimal management for mitigation and adaptation. This study aimed to determine the changes in the vegetation cover of the Bayantal soum in Govisumber province, located in transition zones between the steppe and the Gobi. We obtained MODIS NDVI data with a spatial resolution of 250 m and spanning June, July, and August of 2000 to 2020 from the NASA EOS. We applied Sen’s slope and Mann-Kendal test to detect spatial-temporal changes in vegetation cover and its trend. According to the results, average NDVI values ranged between 0.2 to 0.4 in Bayantal soum. During the past 21 years, the number of NDVI pixels with values of 0.2-0.3 significantly decreased, whereas, the number of NDVI pixels with values of 0.3-0.4 increased. Long-term NDVI series data indicated that vegetation cover in the soum had a positive change or increasing tendency. A significant increase in the NDVI was observed and accounted for 46.3% of the total area of the soum. The decrease in NDVI was estimated at 0.1 percent of the total area of the soum but it was not significant. The remaining areas of the soum experienced variations in NDVI. The analysis revealed that vegetation cover increased by 0.0056 units per year. Overall, the vegetation cover in the Bayan soum increased over the past 21 years, which conflicts with other studies indicating the deterioration. Therefore, remote sensing data and field monitoring surveys are recommended to detect robust changes in vegetation cover. [ABSTRACT FROM AUTHOR]

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