Abstract:Aims Landscape pattern can indicate ecosystem changes. The Otindag Sandy Land, which is located in the southeastern Inner Mongolia Plateau, has been degraded by overgrazing in the past two decades. The purposes of this study are to 1) analyze spatial-temporal dynamics of landscape pattern, 2) determine whether landscape pattern can be used as an indicator of ecological degradation, and 3) explore underlying ecological processes that triggered alteration of landscape pattern. Methods Our approach integrated remote sensing and geographic information system (GIS). The basic sources of data were two Landsat TM/ETM+ satellite images from 1987 and 2000 and field data collected in summer 2001 and 2002. From the images, we distinguished six landscape types within our study area: grassland, fixed sandy land, semi-fixed sandy land, mobile sandy dune, shrub and water body. We performed a supervised classification procedure to derive landscape maps. Using GIS, we analyzed the resultant landscape maps by change detection analysis and transition matrix analysis. Important findings Great change occurred at our study area from 1987 to 2000. Total area of grassland, fixed sandy land and semi-fixed sandy land decreased and patch fragmentation increased. Total area of mobile sandy dune increased about 2.5 times and patches expanded and combined into two sand belts. Change detection showed the same tendencies. Transition of landscape types included grassland converted mainly to sandy land, fixed sandy land transformed into semi-fixed sand y land and semi- fixed sandy land changed mainly to active sandy land. The ecosystem in this region seriously degraded from 1987 to 2000, and effective measures should be taken to prevent further environmental deterioration.