Abstract:
Bijie City, Guizhou Province is located in slope zone between the eastern Yunnan plateau and Qianzhong tableland and hills, which is a typical karst area. Bijie region consists of Dafang, Qianxi, Jinsha, Zhijin, Nayong, Hezhang and Weining counties and Bijie City. It has a fragile ecological environment. In order to better understand Bijie ecosystem composition, structure and change characteristics, in this paper, based on object-oriented classification and spatial statistics and analysis technology, the ecological system of Bijie prefecture in 2000 and 2010 was extracted from Landsat TM image, and the ecosystem composition, structure and characteristics were analyzed quantitatively. The results showed that: from the view of the ecosystem composition and structure, the study area in 2010 was mainly composed of forest land and farmland ecosystem types, accounting for 42.65 % and 42.65 % respectively; in 2000 and 2010, the region had a higher number of patches and the smaller average patches area, indicating a higher degree of landscape fragmentation in the region. Number of patches in 2010 was less than that in 2000, indicating that the study area landscape connectivity was improved totally, the whole landscape tended to be neat. The dry land patches and the average plaque area decreased in 2010, while the coniferous forest and grassland increased, showing that the Grain for Green project worked; The dry land and coniferous forest concentration increased, which indicated that connectivity was enhanced and the landscape became more concentrated. Depending on the statistics of conversion area of ecosystem during 2000 and 2010, the total conversion area of all ecosystem types in the study area was 1 298.25 km2, the upland and paddy field area decreased significantly, the woodland and grassland increased obviously, the land transfer matrix displayed that dryland mainly became forestland or grassland. Due to larger drought area, the area in Bijie, Qianxi, Dafang changed greatly and the ecological transformation intensiy are high, the ecological system type transformation intensity values of eight administrative area were positive, showing that the ecosystem cover types tended to be improving.
