基于遥感的长江口南汇潮滩植被群落时空动态变化

The study of spatial and temporal variations on vegetation communities in Nanhui tidal flat of Changjiang Estuary by using remote sensing

植被是潮滩湿地的主要地物类型之一,其动态变化直接影响着湿地的生态服务功能和经济价值。在地理信息系统(G IS)技术平台的支持下,通过对1949-1982年4幅航片影像和1995-2008年4景不同时相的Landsat TM遥感影像进行解译分析,结合现场调查数据,分析了长江口南汇潮滩植被群落的时空动态变化。结果显示:20世纪80年代之前,分布在海堤外侧自然状态的植被群落随淤涨外延,面积在10 km2以上;20世纪80-90年代,自然冲淤强度减弱,南汇在海堤外侧种植芦苇进行人工促淤,植被处于自然状态与人为影响转换的过渡期,1995年面积达到14.30 km2;2000年以后,人工促淤工程增多,围垦造堤大幅度增加,外来入侵物种互花米草由于自身的促淤优势被大面积的种植,又具有比土著物种芦苇更广的生态幅和更强的竞争优势,逐渐占据主导地位,南汇潮滩植被进入主要受人为影响的新塑造期。2008年植被群落多是零散错综地分布在海堤内侧,植被面积为33.19 km2,其中互花米草占46%。

As the main types of tidal fiat wetland, the spatial and temporal variation of vegetation must have some influences on the ecosystem service and economic value of wetland. Based on the GIS platform, the paper analyzes the vegetation spatial and temporal variation in Nanhui tidal fiat, by using remote sensing technology. The data include five TM data obtained from 1995 to 2008 and four aerial images interpretation results, integrated with the field survey data and previous research results. The results showed that the natural vegetation communities outside the shore bank, with the area of more than 10 km^2, extended to sea area with the tidal flat deposition before 1980s; The vegetation communities were in the transition period from natural stage to man-made stage during 1980s - 1990s, because of the weakened natural erosion and deposition and the cultivation of reed in seawall lateral. The area of vegetation communities reached 14.30 km^2 ; The artificial deposition project gradually reduced. Some areas turned into farmland, while vegetation communities entered a new period of succession after 2000. In 2008, the area of vegetation communities was 33.19 km^2, of which Spartina alterniflora accounted for 46% , and vegetation communities are scattered in the inside of seawall.