Resources Science ›› 2016, Vol. 38 ›› Issue (4): 768-776.doi: 10.18402/resci.2016.04.18

• Orginal Article • Previous Articles     Next Articles

Trends and factors influencing vegetation seasonal dynamics in Changwu County on the Loess Plateau

WEN Xiaojin1(), YANG Xinjun1(), LIU Yanxu2, LIU Xianfeng3   

  1. 1. College of Urban and Environmental Sciences,Northwest University,Xi'an 710127,China
    2. College of Urban and Environmental Sciences,Peking University,Beijing 100871,China
    3. College of Resources Science Technology,Beijing Normal University,Beijing 100875,China
  • Received:2015-08-10 Revised:2016-02-15 Online:2016-04-25 Published:2016-04-25

Abstract:

Vegetation dynamics across the Loess Plateau,China have been widely observed. The evaluation of vegetation cover change and driving factors at the county level and seasonal scale is useful to evaluate the specific effects of vegetation restoration. Based on MODIS-NDVI data from 2000 to 2012,supplemented by Sen+Mann-Kendall modeling,this study analyzed trends in vegetation cover change in Changwu County,and determined climatic driving factors. We found that the interannual average value of NDVI of the study area was increased with a linear tendency of 0.064/10a;the ecological restoration project achieved remarkable results in Changwu County from 2000 to 2012. Vegetation cover showed an increasing trend in most areas of Changwu County. The number of pixels decreasing was small and mainly distributed in Dizhang town and Zhaoren town resulting from urbanization and industrialization. Trends in vegetation cover changes were different between seasons over the 13 years of data and vegetation improvement was most significant in summer. Although vegetation improvement was apparent in autumn,the area was smaller than in summer. Vegetation improvement in spring was weaker than in summer and autumn. The number of decreasing pixels was large in this season,and mainly distributed in the north of the study area. There was a correlation between vegetation growth and temperature/precipitation. Precipitation was the dominant natural factor driving annual vegetation improvement in Changwu County. Spring rain had a significant influence on vegetation growth. The response of vegetation growth to temperature had a time lag of one month. The effect of precipitation on vegetation growth was relatively small at the month scale,and there was no time lag effect because of irrigation as a human adaption can alleviate the threat of low precipitation. Besides land exploitation which had a negative effect on vegetation growth,planting and mitigation can benefit vegetation improvement. The Grain for Green project should have a positive effect on vegetation improvement in Changwu County.

Key words: vegetation improvement, seasonal trend, NDVI, influence factors, Loess Plateau, Changwu County