Acta Geographica Sinica ›› 2019, Vol. 74 ›› Issue (1): 76-86.doi: 10.11821/dlxb201901006

• Climate Change and Surface Processes • Previous Articles     Next Articles

Effects of ecological conservation projects and climate variations on vegetation changes in the source region of the Yangtze River

TANG Jian1,2(),CAO Huiqun1,2,CHEN Jin2()   

  1. 1. Basin Water Environmental Research Department, Changjiang River Scientific Research Institute, Wuhan 430010, China
    2. Key Lab of Basin Water Resource and Eco-environmental Science in Hubei Province, Wuhan 430010, China
  • Received:2017-08-17 Online:2019-01-18 Published:2019-01-18
  • Supported by:
    National Natural Science Foundation of China, No.51609008;Natural Science Foundation of Hubei Province, No.2016CFA092;The Fundamental Research Funds for Central Public Welfare Research Institutes, No.CKSF2015015/SH

Abstract:

Quantitative research on the effects of ecological conservation projects and climate variations on vegetation changes is vital to the ecological benefit evaluation of ecological conservation projects, and has important implications for sustainable ecological rehabilitation management strategies in the source region of the Yangtze River. Based on the normalized difference vegetation index (NDVI) data and meteorological data during 1982-2015, this paper examines the temporal and spatial variations of NDVI; constructs back propagation artificial neural network (BPANN) model to simulate the responses of NDVI to climate factors; and quantifies the effects of ecological conservation projects and climate variations on vegetation changes at the annual and seasonal scales in the source region of the Yangtze River. The results indicate that: (1) Because of the effects of ecological conservation projects and climate variations, vegetation degradation curbed in the source region of the Yangtze River. (2) NDVI increased greatly near the Tongtian River located at relatively low altitudes. Minor increases in NDVI were observed near the Tuotuo and Dangqu rivers located at relatively high altitudes. (3) A time lag (about 1-2 months) existed between NDVI and major climate factors in the source region of the Yangtze River. The goodness of fit of the BPANN model shows that the simulation accuracy is relatively high. The model can be used to simulate the responses of NDVI to climate variations. (4) Ecological conservation projects exerted a slightly greater impact on NDVI changes than they did on climate variations at the yearly time scale (58.5% and 41.5%, respectively). During growing season, ecological conservation projects also exerted a slightly greater impact on NDVI changes than they did on climate variations (63.3% and 36.7%, respectively). During non-growth season, climate variations are the key factor affecting vegetation growth in the source region of the Yangtze River (52.8%). The research results provide a basis for scientific decision-making about the vegetation ecosystem rehabilitation, management and utilization strategies in the source region of the Yangtze River.

Key words: vegetation, ecological conservation projects, climate variation, normalized difference vegetation index, artificial neural network, the source region of the Yangtze River