红树林与互花米草盐沼交界区空间格局变化规律的遥感分析

Remote sensing analysis of the changes in the ecotone of mangrove forests and Spartina alterniflora saltmarshes

红树林和盐沼是世界上重要的滨海湿地类型。在我国东南部沿海,互花米草盐沼和红树林之间的竞争成为一个重要的问题。为了研究红树林和互花米草盐沼之间的空间竞争规律,选取福建漳江口红树林国家级自然保护区为研究区域,收集了1988年至2014年27年间共15期覆盖该区域的Landsat影像和Google Earth影像,采用最大似然分类法提取出红树林与互花米草盐沼的近30 a历史变化信息。历史遥感影像分析表明:1)红树林面积20世纪90年代增长速度最快,2004年以后增长速度变慢;2)互花米草最早出现在2002年,此后以缓慢的速度朝着地势高的区域扩散,2010年后互花米草的扩散速度加快;3)红树林与互花米草的交界区基本保持稳定,部分区域表现为红树林略微向外扩张;4)影响红树林与互花米草盐沼交界区空间格局的因素可能有潮沟的分布和红树林的林冠完整性等。

Mangrove forests and sahmarshes are the most important types of coastal wetlands in the world. In southeastern coastal areas of China, the competition between Spartina alterniflora saltmarshes and mangrove forests has become an important problem. In order to investigate the rules of spatial competition between Spartina altemiflora saltmarshes and mangrove forests, this paper selected Yunxiao National Nature Reserve of Mangroves which locates in Zhangjiang Estuary, Fujian Province, as the study area. We used the Landsat and Google Earth imageries covering this area from 1988 to 2014. Maximum likelihood classification was used to obtain the change of the total area of the mangrove forest and the Spartina aherniflora saltmarsh over nearly 30 years. The results showed that： 1） the expanding rate of the mangrove forest was fast in 1990＂s, but it slowed down after 2004; 2） Spartina alterniflora firstly appeared in the image of 2002 and it spreaded towards the elevated area at a low rate, but the expanding rate was accelerated after 2010; 3） The boundary between the mangrove forest and Spartinaalterniflora mainly remained stable, with an expansion of the mangrove forest in some areas; 4） The distribution of tidal creeks and the closure of mangrove canopy may influence the spatial pattern of the junction region of mangrove forests and Spartina alterniflora saltmarshes.