应用3个时期航空遥感图像为基本信息源,在Arc/Info系统的支持下,建立空间信息库,应用景观破碎度、分维数、优势度、多样性指数、均匀性指数等指标,对洞庭湖区景观空间格局的时空演变进行分析,结果表明:水陆景观之间的交替变化显著,耕地面积减少最多,达30608hm2,水域面积增加最多,净增48978hm2。20a来整个区域的景观破碎度加重,多样性增加,优势度下降。进一步具体分析各景观类型发现,耕地、草地、居住建设用地的破碎度和分离度1980～1990年间表现为增加,1990～2000年则表现为减少,表明湖区的自然保护区建设和退田还湖、移民建镇政策已初显成效。由于受泥沙淤积和退田还湖的影响,20a中水域景观的分布质心整体上移动了2.31km,向东南偏离了53.87°。
Landscape spatial pattern mainly refers to the distribution of patches,which are diffe-rent in size and shape in space owing to the interaction of various ecological activities.The study on landscape spatial pattern provides valuable information for rational management of the environmental resources,and it has been one of the key study fields in landscape ecology as a whole.By using three-period aerial photo s as basic information resource and with the support of Arc /Info,a space information storehouse is built up.Dongting Lake area,located in the middle of Yangtze River valley,lies between27°55'～30°23'N and110°50'～113°45'E,and consists of17counties with an area of28737km 2 .Because of unreasonable anthropogenic exploitation and utilization,the landscape pattern has changed re-markably.Based on the trial of models of landscape fragmentation,dominance,diversity index,evenness index,etc.,the dynamic changes of landscape patterns of Dongting Lake area are presented.The results show that it is remarkable to interchange between different landscapes,especially frequently between cultivated land and water area.The cultivated land decreased sharply by30608ha,while the water area increased48978ha.During the two decades landscape fragmentation has turned worse and diversity increased,while dominance has decreased in the whole region.Fragmentation and separation of the cultivated land,lawn and construction land show an increase process from1980to1990,and it is on the contrary in the last decade,which indicates that wetland preserves and the policy“returning farmland to lake and forest,and resett-lements”have taken effects.Because of sediment deposition and the engineering measures of“returning farmland to lake”,the distribution centroid of water area patches has moved2.31km towards southeast in the last two decades.
