Over the last century urbanization on the landscape has increased and intensified. Urban development has intense impacts on the environment on local, regional and even global scales. As a driving force in global change, the need to understand the dynamics of urban pattern and its change in an accurate and efficient manner is ever more pressingBased on the aerial color infrared photograph in 1985 and the QuickBird satellite image in 2004 and according to the standard for plan and construction of city land use, Guigang City was divided into 11 landscape types. In the landscape classification maps, 31 buffer zones, each being 200m wide, were divided. With the aid of GIS software ArcView 3.2 and landscape pattern analysis software FRAGSTATS 3.3, the landscape spatial patterns of each buffer zone were analyzed on the landscape level and class level. The landscape indices, such as patch size, patch fractal dimension, diversity index and evenness index, were calculated. The results indicated that:
1. The total area of the residential land and the communal facilities land in 2004 covered 46.3% of the entire constructed area of Guigang City and the sum of patch number of the two patch types occupied about 39.7% of the total patch number, while the percentages were 48.2% and 45.4%, respectively, in 1985. This showed that the mosaic landscape with the residential land and the communal facilities land became more and more unobvious following the urban development and the landscape diversity.
2. Based on the gradient analysis with the landscape-level index and the class-level index, there were two business and finance centers existed in the constructed area. One was located in the urban center with a range of 0.8 km; the other was from the 10th to the 16th zone. In each buffer zone, the mean patch size was larger and the landscape shape was more regular in 2004 than in 1985. Furthermore, the Shannon diversity index of each buffer zone was rising in 2004 with the patch richness and the evenness index increasing
3. The landscape index computed for the main landscape types (communal facilities land, industrial estate land, residential land and farmland) in the middle of the buffer zones could reflect the urbanization changing well. The patch size and the patch number of industrial estate land and farmland showed the same changing tendency, while communal facilities land and residential land assumed another same changing tendency. In each gradient zone, the industrial estate land had the most complex shape, the lowest area percentage of each zone and the biggest mean patch size, whereas the communal facilities land and the residential land were opposite to the industrial estate land. The farmland had steady percentage along the buffer zone and its continuous distribution had an important effect on the urban eco\|environment.
4. How to relate the pattern changing characteristics along the buffer zone to the urban ecological process and the urban ecological planning remains to be studied further in the future.