JOURNAL OF NATURAL RESOURCES ›› 2012, Vol. ›› Issue (7): 1200-1213.doi: 10.11849/zrzyxb.2012.07.011

• Special Column:Celebration of the 70th Anniversary of IGSNRR, CAS • Previous Articles     Next Articles

Responses of EVI to Climate and Land-use Variation in Taips County from 2000 to 2008

HU Ying-min1,2, GAO Qiong1, LAN Yu-fang1,2, JIN Dong-yan1,2, XU Xia1   

  1. 1. State Key Laboratory of Earth Surface Processes and Resource Ecology, Beijing Normal University, Beijing 100875, China;
    2. Academy of Disaster Reduction and Emergency Management, Beijing Normal University, Beijing 100875, China
  • Received:2011-12-09 Revised:2012-02-27 Online:2012-07-20 Published:2012-07-20

Abstract: The farming-pastoral zone in northern China has become one of the most vulnerable eco-regions due to the comprehensive effects of climate changes and human activities. As an integral component of ecosystem, vegetation cover dynamics indicated by various vegetation indices from long time series remote sensing data could be used to reflect the ecological and environmental changes. The Grain for Green Project is widely put forward by converting farmland into forests and grasslands, the evaluation of which as a result has become the hot spot of ecosystem researches. Identifying the distinctive impacts of climatic factors and land use management disturbances could help to make more objective assessment of vegetation restoration and guiding the follow-up ecological constructions. This study used Taips County, a typical region in the farming-pastoral zone, as the study area. Based on the data of MODIS-EVI, monthly mean air temperature and precipitation obtained from the nearby 45 weather stations, the spatial-temporal patterns of vegetation cover from 2000 to 2008 were explored. The correlation coefficients between the annual maximal EVI over the whole region and the climatic variables of different months during the growing periods were calculated. Together with the land use data in 2000 and 2005, when northern China was experiencing fast land use shift, we further analyzed the correlation between EVI and climatic variables for different land use types. And EVI changes caused by land use transitions were also studied. The results indicated that from 2000 to 2008, the annual maximal EVI fluctuated with an increasing trend and the vegetation in middle-east of the region grew better than that in the southwest. The average EVI over the whole region of July had a negative correlation with the mean air temperature of June and July and a positive correlation with the total precipitation of the two months. The correlation coefficients were both higher than 0.9, suggesting delayed and accumulative effects. The correlation between EVI and climatic variables of different land use types differed significantly. Before farmland conversions, only the EVI of grasslands had negative correlations with precipitation while after the abrupt land use changes from farmland to forests and grasslands, the EVI of farmland and forests both had higher correlation coefficients than grasslands, interpreting the non-identical results of intensive and extensive land use managements. Different land-use transition patterns resulted in different EVI changes. EVI decreased 2.27% and 1.42% respectively when farmland converted into grassland and forests converted into cropland. The inter-transitions between forests and grasslands also resulted in EVI decrease, pointing out the great uncertainties of environmental protective policies and vegetation restoration projects in case of other natural and human influences.

Key words: climate, land use, EVI, Taips

CLC Number: 

  • Q948.1