Resources Science ›› 2019, Vol. 41 ›› Issue (11): 2131-2143.doi: 10.18402/resci.2019.11.15

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Multi-scale periodic variation of NDVI in July and its response to climatic factors in the Taibai Mountain area

ZHANG Chenhua1,2, LI Shuheng1,2(), BAI Hongying1,2, ZHU Xianliang1,2, YANG QI1,2   

  1. 1. College of Urban and Envirormental Science, Northwest University, Xi’an 710127, China;
    2. Shaanxi Key Laboratory of Earth Surface System and Environmental Carrying Capacity, Xi’an 710127, China;
  • Received:2019-07-13 Revised:2019-10-14 Online:2019-11-25 Published:2019-12-03
  • Contact: LI Shuheng E-mail:lish@nwu.edu.cn

Abstract:

Multi-scale periodic variation is one of the important frontier issues of vegetation research. It is of great significance to revealing the pattern and complexity of vegetation system changes. Based on the NDVI in July data of recent 172 years reconstructed by using the tree-ring width chronology of the Taibai Mountain area, ensemble empirical mode decomposition (EEMD) was used in this study to analyze the response of NDVI to climatic factors and to analyze the variation characteristics of NDVI’s time series at different temporal scales. The results indicates that the NDVI in July showed a weak nonlinear upward trend for the north and south slopes of the Taibai Mountain area. The NDVI on the north slope/south slope showed interannual scale periods of 3.3 a/3.5 a, 8.1 a/8.8 a, and interdecadal scale periods of 18 a/19.1 a, 36 a/34.4 a, and 64.8 a/68.8 a, respectively. The interannual scale changes reveal the details of the fluctuations of the original sequence of NDVI, while the interdecadal scale changes reveal the alternation of increase and decrease in different periods. The interannual scale of NDVI on the north slope fluctuated greatly, while the interdecadal scale of NDVI on the south slope fluctuated strongly. The main factor affecting NDVI on the interannual scale is precipitation, while the main factor affecting NDVI on the interannual scale is temperature. The NDVI on the north slope is controlled by hydrolic factors and the NDVI on the south slope is more affected by heat factors. The analysis of the multi-scale period of NDVI is of great significance for studying the variation characteristics of vegetation growth in the Taibai Mountain area.

Key words: NDVI, nonlinear variation, multi-scale period, ensemble empirical mode decomposition (EEMD), climate response, Taibai Mountain