Dynamic analysis of land use/change and landscape pattern in lake-area of Minqin in recent 15 years.

Land use/ coverchanges(LUCC) such as desertification,forest degradation,has induced the reduction environment services,with large negative consequences for mankind.The study addressed the analysis of LUCC and landscape patterns in lake-area of Minqin during the recent 15 years,where the ecological environment has been deteriorating for many years in Gansu Province.The results contribute to the understanding of how land use-cover and landscape patterns change in study area.The data were derived from LANDSAT TM5 imagery acquired in 1991, 1998 and 2005 respectively,in addition some auxiliary data of this area were used in the research.All the analysis were based on RS,GIS technology and many indices computed for analysis of LUCC and landscape index,such as land-use composition index,land-use degree index,the fractal dimensions,diverse index,the superiority,the broken and so on.These conclusions can be drawn as follows:(1) The main land use type in study area are farmland,urban and build-up,and unused land.The analysis shows that land use types have remarkablychanged during 1994- 2005,in which the farmland area has been increased by 9 385.47 hm~2 and sandy area increased by 4.79%;The land use composition index in recent 15 years also increased,however,the exploitation degree trend was opposite; land-use types interchange intricately and human activities influence the change intensively;(2) Lake-area' s landscape pattern changed significantly.The landscape indices indicated that the fragmentation of grassland patch has become bigger and its distribution isdispersed,the pattern of farmland tends to be contiguous and convergent;at landscape level,diversity declined,dominance raised and the landscape heterogeneity reduced;(3 ) On the macro-level, the oasisi was drifted 348.67m to the southwest.The ecological environment of lake-area became worse.