Chin J Plant Ecol ›› 2016, Vol. 40 ›› Issue (12): 1245-1256.DOI: 10.17521/cjpe.2015.0389

• Research Articles • Previous Articles     Next Articles

Changes in normalized difference vegetation index of deserts and dunes with precipitation in the middle Heihe River Basin

Fang LI1,2, Wen-Zhi ZHAO2,*   

  1. 1Research Institute of Grassland Science, Chinese Academy of Agricultural Sciences, Hohhot 010010, China
    2Institute of Northwestern Eco-environment and Resource, Chinese Academy of Sciences, Linze Inland River Basin Research Station, Chinese Ecosystem Research Network, Lanzhou 730000, China
  • Online:2016-12-10 Published:2016-12-30
  • Contact: Wen-Zhi ZHAO

Abstract: AimsPrecipitation is the major water source for desert ecosystems, with its temporal dynamics significantly driving the changes of ecosystem structure and function in desert regions. The objectives of this study are to evaluate the changes in normalized difference vegetation index (NDVI) with seasonal precipitation and different climate years in two cover types (desert and dune).MethodsBased on the daily rainfall dataset of 2000-2012 in the middle Heihe River Basin in Northwest China and the NDVI extracted from the moderate resolution imaging spectroradiometer (MODIS) images, we performed linear regression analysis to examine the correlation of NDVIINT (accumulated NDVI) with precipitation in two cover types (desert and dune). Two measures of the precipitation are Pc (cool-season precipitation from last September to late February) and Pw (warm-season precipitation in between March and August), while NDVI was characterized with NDVIINT-pys (previous-year during the different climate years (dry: 2001-2003, wet: 2004-2007)) and the different periods of a growing season (i.e. whole growing season from May through September, early growing season in between May and June, and late growing season in between July and September).Important findings We found that: (1) the determinants of growing season NDVIINT and their order were NDVIINT-pys > Pc > Pw for the deserts, while the order was Pw > NDVIINT-pys for the dunes. The determinants and their order of NDVIINT in early growing season were NDVIINT-pys > Pc for the desert, while they were NDVIINT-pys > Pc = Pw for the late growing season. However, for the dunes, NDVIINT of the early and late growing season appeared determined by NDVIINT-pys and Pw, respectively. (2) During the dry and wet periods, precipitation was not a significant factor influencing NDVIINT for the desert and dune. However, significant increases in NDVIINTwere observed at dune under wet condition. With the wet years continued, the length of the wet years become an important determinant of NDVIINT at both cove types, particularly at dune. In addition, it appeared that different changes in NDVI with precipitation existed between the two cover types, but with very similar effects of time-lag. These findings provide useful references for further understanding the mechanisms of NDVI changes with precipitation.

Key words: accumulated normalized difference vegetation index (NDVIINT), precipitation of cold season, precipitation of warm season, dry and wet climate period, lag time, ecohydrology