Identification of the changes during growing and the best growth period of the oasis vegetation in the Heihe River basin using SPOT-VEGETATION NDVI
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DOI:10.7606/j.issn.1000-7601.2012.06.35
Key Words: oasis vegetation growth  the best growth period  NDVI  Heihe River basin
Author NameAffiliation
XIE Yaowen College of Resource and Environmet, Lanzhou University, Lanzhou, Gansu 730000, China 
ZHAO Benfu College of Resource and Environmet, Lanzhou University, Lanzhou, Gansu 730000, China 
ZHAO Hong College of Resource and Environmet, Lanzhou University, Lanzhou, Gansu 730000, China 
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Abstract:
      Based on the SPOT-VEGETATION NDVI data of year 2008 of the Heihe River basin, the oasis growing changes were quantitatively analyzed by use of mathematical statistical method, linear regression trend analysis and per-centage change range analysis. The result showed that the growing stage of oasis vegetation was very significant in one year. The oasis vegetation trended to significantly raise on No.1-18 ten-days(from January to June) No, fluctuated on 19-22 ten-days(from July to early August) and decreased on No.23-36 ten-days (from mid August to December). The rate of oasis vegetation growing change indicated apparent periodieity. From early January to late June the oasis vege-tation grew better and better, but the fast increase of vegetation growing occurred from the middle of May to late May. The vegetation growth was getting worse from mid-August to late December, but the fast redueing of vegetation growth achieved mostly from late September to mid-October. The oasis vegetation growing change had obvious spatial differentia-tion. Yearly growing maximum change area was located in the main area of oasis. The best period of vegetation growing for the whole area varied from region to region in general, the area with the best period occurring on No.22 ten-days was dominative, followed by the 20 ten-days and 18 ten-days, etc. Therefore, the remote sensing images in early August can be selected for the study of the whole basin oasis, and the remote sensing images in late June, mid-July or late September can be selected for the study of the local area.