Background  Urban landscape is the most important concern in the study of the current urban landscape pattern, and it is also one of the fastest dynamic changes in the surface landscape. The study area is Urumqi, the capital and the centre of culture, economy and transportation in Xinjiang Uyghur Autonomous Region, located in north-western China and characterized by an arid landscape. With the rapid development of urbanization in Urumqi, the contradiction between urban layout and the structure of land use is becoming increasingly sharp. The objective of this paper is to study the formation, distribution pattern and transformation of each landscape pattern in Urumqi city during last 25 years, and to provide scientific and reasonable references for the landscape management and sustainable development of the city.

Methods  According to the characteristics of the city development and environmental factors in Urumqi, a reasonable and effective use of moving window method is to analyze the spatial layout and internal level difference of landscape fragmentation in Urumqi built area. Transferring matrix and landscape indexes (patch density, largest patch index, landscape separation index, number of patches, Shannon's diversity index, patch area, and landscape area) are used to analyze spatial-temporal changes of landscape fragmentation and dynamic changes in Urumqi city based on the data source Landsat TM/ETM+, OLI images taken at the same month in 1990, 2002 and 2014.

Results  1) The changes of landscape types in Urumqi during the past 25 years mainly are the increase of landscape area and the transformation between different types of landscape, which shows obvious temporal and spatial changes. 2) Speed of urbanization and the degree of landscape fragmentation has increased, the dominance has reduced, and the heterogeneity has risen. The degree of landscape fragmentation is aggravated, and landscape types tend to be more diversified. 3) In 1990, the city is in a development stage, and the level of urbanization is low. In 2002, the speed of urban expansion has increased significantly, and the level of urbanization has improved. In 2014, the urban expansion is faster, the level of urbanization is higher, and the city is in a stage of rapid development.

Conclusions  In the recent 25 years, with the rapid development of urbanization in the research area, the total area of each landscape type shows increasing trend, human impact has intensified, the fragmentation of landscape has strengthened, diversifying trend has occurred, and dominance degree has decreased. The research may provide a scientific and reasonable reference for landscape management and urban sustainable development in the intensively developed arid urban landscape of Urumqi.