An analysis of ecosystem change around deserts of central China and Mongolia

Abstract

The purpose of this research is analyzing the ecosystem surrounding the Gobi desert in North Asia quantitatively as well as qualitatively more concretely. We used Normalized Difference Vegetation Index (NDVI) derived from VEGETATION (VGT) sensor onboard the SPOT 4 and 5 satellite during 1999~2007. Monitoring ecosystem of this area is necessary for the environment change, because the vegetation of North Asia is a hot spot in global environment change and this improved study will allow us to predict areas prone to the rapid environmental change. We classify into eight classes and compare our classified map with MODerate resolution Imaging Spectrometer (MODIS) global land cover. Three classes (barren land, shrubland and grassland) were focused on our analysis. Since there are significant extensions of barren land from 1992 to 1999, 47.8% (1916674 pixels) of 1992's shrubland changed to barren land in 1999. Among the five terms (1999-2003, 2003-2005, 2005-2007, 1999-2005, 1999-2007), there are many changes during 1999-2003 for barren land and during 2005-2007 for shrubland and grassland. Also, forward change and backward change analysis were considered in this study between 1999 and 2007. Quantities of the positive change pixels in forward change for barren land are similar to the number of negative change pixels in backward change. For shrubland and grassland, negative change area is bigger than positive change area in both forward change and backward change. Precipitation patterns for nine years are nearly similar to our classified map. We have to keep a careful watch on the problems related to ecosystems in this area constantly.