Journal of Ecology and Rural Environment ›› 2022, Vol. 38 ›› Issue (11): 1427-1436.doi: 10.19741/j.issn.1673-4831.2022.0201

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Study on Spatial and Temporal Changes of Vegetation Coverage in Gannan Prefecture Based on Different Geomorphological Zones and Their Influencing Factors

MA Yue1, WANG Lu-cang1, ZHAO Rui-dong2, CHANG Fei3   

  1. 1. College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China;
    2. College of Resources and Environmental Sciences, Xinjiang University, Urumqi 830046, China;
    3. School of Architecture and Urban Planning, Shenzhen University, Shenzhen 518000, China
  • Received:2022-03-14 Published:2022-11-23

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Abstract: Gannan Tibetan Autonomous Prefecture is situated at the northeastern edge of the Tibetan Plateau, in the transition area between the first and second terraces, with complex and variable landform types and very pronounced differences in vegetation coverage. Based on MODIS EVI data from 2000 to 2018, the spatial and temporal trends of the change of vegetation coverage in different geomorphological zones of Gannan Prefecture and their influencing factors were studied and the results show that: (1) Based on temporal changes, the enhanced vegetation index (EVI) growth trends of the northwestern mountain plateau zones, the eastern mountainous hilly zones, and the southern Mindie Valley zones in Gannan Prefecture between 2000 and 2018 were 0.000 8, 0.001 1, and 0.000 9 a-1, respectively. (2) Based on spatial changes, the fractional vegetation coverage (FVC) of Gannan Prefecture demonstrated a decreasing spatial distribution from southwest to northeast. The mountainous area in the northwest was dominated by high coverage, the mountainous and hilly area in the east was dominated by medium coverage, and the Mindie Valley area in the south showed the alternate distribution of low coverage and high coverage. (3) In Gannan, the proportion of EVI improvement (approximately 54%) is greater than the proportion of degradation (about 37%). The majority of degraded EVI areas are located in the northwestern mountain plateau of Maqu and Luqu and the southern valleys of Diebu. The majority of EVI improvement areas are located in the eastern mountainous and hilly terrain. (4) The EVI influencing factors in various geomorphological zones of Gannan Prefecture are different. In this regard, human activity factors and natural environmental factors are the primary determinants of EVI in the northwestern mountain plateau zones, whereas natural environmental factors are the primary determinants of EVI in the eastern mountainous hilly zones and the southern Mindie valley zones.

Key words: vegetation coverage level, spatial and temporal evolution, distinct geomorphological zone, influencing factor, Gannan Prefecture

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