江苏盐城滨海湿地外来种互花米草的时空动态及景观格局

Spatiotemporal dynamics and landscape pattern of alien species Spartina alterniflora in Yancheng coastal wetlands of Jiangsu Province,China

基于1992—2007年的遥感影像和野外调查数据,在地理信息系统的支持下,应用景观生态学理论和转移矩阵方法,定量分析了江苏盐城滨海湿地外来种互花米草的时空动态及其景观格局的演变规律.结果表明:研究区互花米草面积由1992年的3561hm2上升至2007年的14491hm2,增幅达306.94%,累计转入和转出面积分别为26291和15361hm2;其中,江苏盐城国家级自然保护区核心区的互花米草面积由1992年的597hm2增长到2007年的2814hm2,年增幅达24.74%.研究期间,该区互花米草空间分布格局由初始的河口地带零星斑块逐渐演变为连续带状,并扩展到射阳河口至梁跺河口之间的滩涂外围;研究区互花米草的斑块重心向东南方向移动(2.92km),平均斑块面积先增(1992—2002年)后降(2002—2007年),最大斑块指数及面积加权临近度指数逐年递增,斑块形状趋向规则化.

Based on the 1992-2007 remote sensing images and field survey data, and by using the landscape ecology theories and the method of conversion matrix, the spatiotemporal dynamics and landscape pattern of Spartina alterniflora in Yancheng coastal wetlands were analyzed by GIS. The results showed that the total area of S. alterniflora along the whole coastal beaches of Yancheng increased from 3561 hm2 in 1992 to 14491 hm2 in 2007, with a growth rate of 306.94%. In 1992-2007, the total area of S. aherniflora conversion-in and conversion-out was 26291 hm2 and 15361 hm2, respectively, and the S. alterniflora community in the core area of Yancheng National Nature Reserve expanded from 597 hm2 to 2814 hm2, with an annual growth rate of 24.74%. The S. alterniflora community transformed from scattered patches in estuarine regions into continuous belt pattern mainly distributed in the periphery of coastal wetlands from Sheyang River to Liangduo River. Its centroid moved to the southeast, with a distance of 2.92 km. The average area of patches increased from 1992 to 2002, and then decreased from 2002 to 2007. The largest patch index and area-weighted contiguity index increased year by year, and the shape of patches tended to be more regular.