A landscape-scale assessment of steppe degradation in the Xilin River Basin, Inner Mongolia, China

Steppe degradation is a major ecological and economic problem in the Inner Mongolia steppe region, China because it reduces grassland productivity and leads to desertification. The objective of this study was to assess the spatial extent and severity of steppe degradation in the Xilin River Basin, Inner Mongolia using a landscape-scale approach. Our approach combined information from field survey records, existing vegetation maps, and remote sensing data to determine the different degrees of degradation for diverse steppe communities at the local scale and their spatial pattern at the landscape scale. We also developed a steppe degradation index (SDI) that integrates the information on the spatial extent and severity of steppe degradation. Our results showed that the total area of degraded steppe in this region increased from 7191.3 km in 1985 to 7689.3 km (72% of the total basin) in 1999. We used SDI to quantify the degree of degradation and its changes in space and time. The SDI maps revealed that large-scale patterns of steppe degradation were related to landform types. For both 1985 and 1999, the four landforms exhibited increasing degrees of degradation in the following order: low mountains > lava tablelands > hills > high plains. Several seriously degraded regions in the Xilin River Basin were identified. This study demonstrates the effectiveness of combining remote sensing data and synoptic ecological indices in assessing ecosystem degradation, and provides useful information for improving ARTICLE IN PRESS *Corresponding author. School of Life Sciences, Arizona State University, Tempe, AZ 85287, USA. E-mail address: [email protected] (J. Wu). 0140-1963/$ see front matter r 2004 Published by Elsevier Ltd. doi:10.1016/j.jaridenv.2004.01.004 grassland management practices and restoring the degraded steppe vegetation in the Xilin River Basin, Inner Mongolia. r 2004 Published by Elsevier Ltd.