洞庭湖区景观镶嵌结构和分形特征研究

利用1980、1990、2000年三期TM影像，应用遥感、地理信息系统技术和景观生态学相结合的方法研究了洞庭湖区景观镶嵌体的结构和形态特征。结果表明：洞庭湖区景观格局与动态特征以耕地、水域、居住建设用地变动为主；各种景观类型的分维数各不相同，分维数的大小依次是：耕地﹤未利用地﹤建设用地﹤水域﹤林地﹤草地，其中建设用地的分维数最接近于1.5，处于最不稳定状态，草地和林地分维数年际波动不大，处于最稳定的状态，耕地随着时间的推移，分维数不断降低；同一种景观类型的分维数在不同地貌条件下也存在差异，其中耕地、水域和居住建设用地的分维数随海拔增加呈增加趋势，草地和林地的变化则表现为相反，这种差异反映了地貌、地势、区位条件和人类活动对于同一景观类型的斑块形态的影响。

FRACTAL MODEL STUDY ON MOSAIC STRUCTURE OF DONGTING LAKE AREA

Dongting Lake Area, located in the middle reaches of Yangtze River, lies between 27°55′~30°23′N and 110°50′～113°45′E, and consists of 17 counties with an area of 28 737 km2. Because of non rational anthropogenic exploitation and utilization, the landscape pattern has changed remarkably in this area. Based on the TM image in 1980, 1990 and 2000, fractal dimension values of each landscape of the mosaic structure were analyzed for Dongting Lake Area under the support of RS and GIS technology and landscape ecology methods. It is indicated that the landscape pattern changed remarkably among cultivated land, water area and construction land. The fractal dimension of each landscape element among the five types was different from that of the other one. Each landscape factor can be ranked according to the fractal dimension of the mosaic structure: cultivated land < unutilized land < construction land < water area < forest < lawn. The fractal dimension of construction land approached to 1.5, which was the most unstable landscape element. On the contrary, the dimension of the lawn and forest changed gently, and it was the most stable landscape element. The simulative result by fractal model showed that the mosaic structure of natural landscape was influenced by physiognomy: the fractal dimension of cultivated land, construction land and water area increased along with the rise of altitude and vice versa is the dimension of lawn and forest. It is shown that physiognomy, hypsography, position and humankind affect the fractal dimension of landscape.