PROGRESS IN GEOGRAPHY ›› 2019, Vol. 38 ›› Issue (8): 1248-1258.doi: 10.18306/dlkxjz.2019.08.013

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Spatiotemporal variations of NDVI of different land cover types on the Loess Plateau from 2000 to 2016

SUN Rui1,2,CHEN Shaohui1,*(),SU Hongbo1   

  1. 1. Key Laboratory of Water Cycle and Related Land Surface Processes, Institute of Geographic Sciences and Natural Resources Research, CAS, Beijing 100101, China
    2. University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2018-12-12 Revised:2019-01-31 Online:2019-08-25 Published:2019-08-25
  • Contact: CHEN Shaohui E-mail:chensh@igsnrr.ac.cn
  • Supported by:
    National Natural Science Foundation of China(41671368);National Natural Science Foundation of China(41371348);Strategic Priority Research Program A of the Chinese Academy of Sciences(XDA20010301)

Abstract:

Understanding the spatial-temporal changes of vegetation and future trends of spatial pattern is of great significance to regional environmental protection and ecological construction. In order to understand the vegetation changes on the Loess Plateau after the implementation of the Grain for Green Project, the spatial-temporal variation characteristics of annual maximum Normalized Difference Vegetation Index (NDVI) (NDVIymax) and growing seasonal mean NDVI (NDVIgsmean) were analyzed based on MOD13A1 data for the Loess Plateau during 2000-2016, supplemented by Sen+Mann-Kendall, coefficient of variation, and Hurst index analysis. The results indicate that: 1) NDVIymax and NDVIgsmean showed a fluctuating growth trend from 2000 to 2016, with growth rates of 0.0070/a (P<0.01) and 0.0063/a (P<0.01), respectively, and the ecological environment improved continuously. 2) NDVIymax and NDVIgsmean showed that the area of vegetation coverage on the Loess Plateau with increasing trend were much higher than that with decreasing trend (93.42% and 96.22% versus 6.58% and 3.78%). This means that vegetation coverage was improving. With regard to the trends of change of the two evaluation indices, the performance of different land cover types slightly differed. The area of forest with most significant increasing trend was 73.02% and 82.60%, followed by cultivated land (47.87% and 67.43%) and bare land (47.03% and 61.68%). The coefficient of variation of NDVIgsmean was smaller than that of NDVIymax, and the stable area was 63.31% and 56.64%, respectively. Of the two evaluation indices, the coefficient of variation of forest was the smallest, representing the best stability. According to the coupling results of NDVI and Hurst index, the areas with increasing trend of NDVIymax account for 41.35%, and the areas with degrading trend account for 58.65% of the total area in the future. The areas with increasing trend of NDVIgsmean account for 49.19%, and the areas with degrading trend account for 50.81% of the total area. The two evaluation indices show that shrubland has the best growth trend. The areas of forest and cultivated land with degrading trend would be greater than 50%. The vegetation status in the areas of unsustainable increase and sustainable degradation need continuous attention of researchers.

Key words: Loess Plateau, NDVI, MOD13A1, vegetation change, land cover