Wang Anqi, Chen Jiadai, Jing Changwei, Ye Guanqiong, Wu Jiaping, Huang Zhixing, Zhou Chaosheng
Institute of Islands and Coastal Ecosystems, Zhejiang University, Hangzhou, China.
Zhejiang Mariculture Research Institute, Wenzhou, China.
PLoS One. 2015 Aug 11;10(8):e0135538. doi: 10.1371/journal.pone.0135538. eCollection 2015.
The exotic plant Spartina alterniflora was introduced to Yueqing Bay more than 20 years ago for tidal land reclamation and as a defense against typhoons, but it has rapidly expanded and caused enormous ecological consequences. Mapping the spread and distribution of S. alterniflora is the first step toward understanding the factors that determine the population expansion patterns. Remote sensing is a promising tool to monitor the expansion of S. alterniflora. Twelve Landsat TM images and Support Vector Machine (SVM) were used to delineate the invasion of S. alterniflora from 1993 to 2009, and SPOT 6 images and Object-Based Image Analysis (OBIA) were used to map the distribution of S. alterniflora in 2014. In situ data and Unmanned Aerial Vehicle (UAV) images were used as supplementary data. S. alterniflora spread rapidly in Yueqing Bay over the past 21 years. Between 1993 and 2009, the area of S. alterniflora increased by 608 times (from 4 to 2432 ha). The rapid expansion of S. alterniflora covered almost all of the bare mudflats around the mangrove forests and the cultivated mudflats. However, from 2009 to 2014, the rate of expansion of S. alterniflora began to slow down in Yueqing Bay, and the total area of S. alterniflora in Yantian decreased by 275 ha. These phenomena can be explained by the landscape changes and ecological niches. Through the expansion of S. alterniflora, it was found that the ecological significance and environmental impact of S. alterniflora was different in different regions in Yueqing Bay. The conservation plans for Yueqing Bay should consider both the positive and negative effects of S. alterniflora, and the governmental policy should be based on the different circumstances of the regions.
20多年前，外来植物互花米草被引入乐清湾用于围垦造田和抵御台风，但它迅速扩散并造成了巨大的生态后果。绘制互花米草的扩散和分布情况是了解决定其种群扩张模式因素的第一步。遥感是监测互花米草扩张的一种很有前景的工具。利用12景陆地卫星专题制图仪（Landsat TM）图像和支持向量机（SVM）来描绘1993年至2009年互花米草的入侵情况，并利用SPOT 6图像和基于对象的图像分析（OBIA）来绘制2014年互花米草的分布情况。实地数据和无人机（UAV）图像用作补充数据。在过去21年里，互花米草在乐清湾迅速扩散。1993年至2009年间，互花米草的面积增加了608倍（从4公顷增加到2432公顷）。互花米草的迅速扩张几乎覆盖了红树林周围所有的裸露泥滩和养殖泥滩。然而，2009年至2014年期间，乐清湾互花米草的扩张速度开始放缓，盐田互花米草的总面积减少了275公顷。这些现象可以通过景观变化和生态位来解释。通过互花米草的扩张发现，互花米草在乐清湾不同区域的生态意义和环境影响不同。乐清湾的保护规划应考虑互花米草的正负效应，政府政策应根据不同区域的不同情况制定。
