Relationship between landscape fragmentation and oasis evolution : a case study of Suzhou Oasis in arid China

Landscape fragmentation in arid area under the global Land Use/Cover Changehas drawn more attention in research of arid landscape ecology recently. In this study, the evaluated oasis evolution and its landscape fragmentation in Suzhou Oasis, a typical agricultural oasis in the middle reach of the Heihe River watershed. Oasis maps were obtained from Landsat TM images for 1990, 1999 and 2010, respectively. The results indicated that during 1990 to 2010, the change of oasis area was dominated by an increase of farmland, grassland and constructed land. The oasis area had increased mainly due to the conversion of farmland, unused land to grassland, and rapid urbanization. Landscape fragmentation index changed over time in the 15 towns, and there was a decrease of number of patches (NP), patch density (PD) and largest patch index (LPI), and an increase in division index (DIV) and Shannon's density index (SHI), suggesting that the change of landscape fragmentation degree had slowed down gradually. An improved method is used to describe the villages and towns scales of landscape fragmentation of the oasis evolution and fragmentation process.