CollectHomepage AdvertisementContact usMessage

Arid Land Geography ›› 2020, Vol. 43 ›› Issue (4): 1041-1050.doi: 10.12118/j.issn.1000-6060.2020.04.19

• Biology and Pedology • Previous Articles     Next Articles

Spatio-temporal characteristics and influencing factors of vegetation coverage in urban agglomeration of Guanzhong Plain

WANG Zhi-guo, BAI Yong-ping, CHE Lei, CHEN Zhi-jie, QIAO Fu-wei   

  1. College of Geography and Environmental Science,Northwest Normal University,Lanzhou 730070,Gansu,China
  • Received:2019-10-25 Revised:2020-06-08 Online:2020-07-25 Published:2020-11-18

Abstract: Vegetation is an important indicator of environmental changes in global and regional ecosystems,and it is also one of the resources that make an important contribution to human social activities. To study the response of vegetation coverage to natural and human factors in different parts of the Guanzhong Plain urban agglomeration in western China,we divided the region of interest into three vegetation areas for our research. We selected MODIS-NDVI remote-sensing data obtained during 2000-2017. Using trend analysis,exploratory spatial data analysis,and geodetector methods,we studied the evolution and distribution characteristics of vegetation cover during those 18 years from the perspectives of temporal evolution and spatial distribution. We quantitatively analyzed the main factors affecting vegetation coverage. We first processed remote-sensing data by such methods as projection conversion,splicing,and maximum-value synthesis and then applied batch image cropping using Python. The remote-sensing and meteorological data were categorized by applying statistical methods. From the processed data,we drew the following conclusions:(1) During the study period,vegetation coverage of the Guanzhong Plain urban agglomeration showed a significant upward trend. The average NDVI growth rate was 0.077 every 10 years,and the characteristics of periodic changes were obvious. Among them,the 2005-2007 and 2011-2013 periods increased significantly,and the maximum ascent rate reached 0.05 per year. (2) Our spatial data generally confirmed the distribution characterized as “high in the south and low in the north,” and vegetation coverage improved overall in the study area. The high-value areas are mainly distributed on the northern slope of the southern Qinling Mountains,which is more affected by climatic factors. The vegetation coverage is increasing slowly and has slightly improved. The low-value areas are concentrated on the edge of the Loess Plateau,and the vegetation coverage is obviously increasing there,whereas a small portion of the central part of the Guanzhong Plain showed slight to severe degradation,with Xi’an and its neighboring cities being the most typical. (3) Hot spots are mainly distributed in the Qinling Mountains and the central of the Guanzhong Plain,while cold spots are concentrated along the margins of the Loess Plateau,where vegetation coverage is mainly increasing. Hot-spot areas continue to increase,having reached a maximum of 45.07% in 2013,while the number of cold spots continues to decrease,having been reduced to 9.82% in 2017. The hot and cold spots are mainly distributed in the central plains and northern areas,which have changed from continuous to scattered distribution,and the total volume is continuously decreasing. (4) The most-prominent influences on vegetation coverage are natural factors,among which temperature and precipitation are dominant. The determinant q values are 0.955 and 0.931,respectively,the influence of temperature being greater than that of precipitation. The influence of human factors is important but not prominent; the determinant q value of the GDP factor reaches only 0.387. The conclusions of this paper could provide some theoretical basis to improve vegetation-coverage environment in the study area.

Key words: NDVI, trend analysis, ESDA, Geodetector, urban agglomeration of Guanzhong Plain