Analyzing landscape degradation using landscape ecological metrics, remote sensing and GIS (Case study: Doiraj watershed, Ilam province)

Rapid land-use/land cover changes have taken place in many arid and semi-arid regions of Iran such as west of Iran over the last decades due to demographic pressure, agricultural pressure, government polices and environmental factors such as drought. This study was aimed to investigate the trends of changes in the landscape, in Doiraj Watershed. In order to provide land cover maps, the satellite images of TM 1985, ETM+2000, ETM+2007 were applied and landscape metrics of class area, largest patch index, number and mean patch size, patch density and edge density were used to quantify landscape patterns. Various class-level landscape pattern metrics were calculated using FRAGTATS, in order to analyze landscape fragmentation. The results of landscape ecology change revealed that in this area during the first period (1985 - 2000), the area of forest lands decreased to 3,415 hectares, while the agricultural lands with 3514 hectares showed an increasing trend. On the other hand, the area of fair rangelands (20,440 hectares) showed a decreasing trend (in both periods) contrary to the area of poor rangelands, indicating the degradation process in the study area. Our results clearly showed that increased number of patches and decreased mean patch area were two important fragmentation indicators and the trend of landscape degradation and fragmentation was increasing. Therefore, the results necessitated paying attention to the quality of land use and cover in the region for decreasing the degradation of natural resources.