Monitoring the temporal-spatial changes of vegetation cover and drivers in Tian Shan ecoregions, China

Autorzy

• Seyed Omid Reza Shobairi Chinese Academy of Sciences, Xinjiang Institute of Ecology and Geography, Urumuqi, 830011, China;
  University of Chinese Academy of Sciences, Beijing, 100049, China
• Sun Lingxiao Chinese Academy of Sciences, Xinjiang Institute of Ecology and Geography, Urumuqi, 830011, China, sunlx@ms.xjb.ac.cn;
  University of Chinese Academy of Sciences, Beijing, 100049, China
• Zhang Haiyan Chinese Academy of Sciences, Xinjiang Institute of Ecology and Geography, Urumuqi, 830011, China;
  University of Chinese Academy of Sciences, Beijing, 100049, China
• Li Chunlan Chinese Academy of Sciences, Xinjiang Institute of Ecology and Geography, Urumuqi, 830011, China;
  University of Chinese Academy of Sciences, Beijing, 100049, China
• He Jing Chinese Academy of Sciences, Xinjiang Institute of Ecology and Geography, Urumuqi, 830011, China;
  University of Chinese Academy of Sciences, Beijing, 100049, China
• Behnam Asghari Beirami K.N. Toosi University of Technology, Department of Photogrammetry and Remote Sensing, Tehran, Iran

Abstract

This study analyzed satellite data from 2000 to 2022 in the Tian Shan ecoregions of northwestern China to investigate relationships between climate, environment, soil conditions, and human activities on constantly changing vegetation fluctuations. The NDVI index outperformed EVI over the period, with peak values of 0.56 and 0.33, respectively. NDVI trends indicated a higher slope of 5.15 compared to 4.91 for EVI. Analysis showed that vegetation area had expanded over time, with the lowest coverage between 2000 and 2005, but then, it spread due to varying degree of human activities’ impacts from 0 to 63. Tests revealed significant negative correlations between soil moisture and EVI/NDVI indexes attributed to natural water phenomena causing vegetation stress. Positive correlations were found between EVI/NDVI with actual evapotranspiration and snow, while negative with wind speed and radiation. The study also found a positive correlation between NDVI and measures of human activity, indicating restoration efforts, project implementations, and soil management preventing erosion expanded vegetation. Overall, the study concluded that human activities had a greater influence than climate through water and soil preservation, resulting in more vegetation expansion over time. Indigenous resource concepts also significantly contributed to long-term preservation efforts evidently maintaining and strengthening vegetation in the ecoregions. These findings highlight the efficacy and resilience of human activity in overcoming climatic and environmental challenges. While human factors can potentially harm the environment and renewable resources, long-term planning and preservation efforts, as evident in the Tian Shan ecoregions, have successfully preserved and strengthened the vegetation.

Keywords

• EVI
• ecoregion
• drivers
• GEE
• NDVI
• climate change