The aim of this study was to develop a comprehensive index system based on remote sensing (RS) and geographic information system (GIS) techniques to evaluate the status quo of ecological security in the farming–pastoral zone of northern China, for the purpose of facilitating sustainable development in ecotone regions. Taking a typical transitional piedmont region with farming–pastoral production mode as a case study area, the region's present ecological security situation was evaluated by constructing an index system with three types of indicators. These indicators were: 1) vegetation growth, measured by the decadal difference in the normalized difference vegetation index (NDVI); 2) change in landscape patterns, measured by the deviation of present from potential landscapes; and 3) severity of soil erosion, measured by organic matter content in topsoil. Data for the indicators, derived from RS images, historical maps, field surveys, and archival materials, were all mapped with the aid of a digital elevation model (DEM), according to their conjugation relationships. The results were obtained by classifying different combinations of elements in an index matrix of three indicators by means of mapping. The final results show that nearly the entire study area was in a condition ranging from somewhat insecure (SIN) to insecure (INS), with an average score of 3.46 in a 5-grade range, indicating declining ecological security. The situation was better in the farming–pastoral district. The whole region needs to adjust its production modes to learn from practices in the farming–pastoral district, in order to alleviate deterioration and improve ecological security in the region.
