Dynamic characteristics of vegetation communities in the floodplain wetland of Lake Poyang based on spatio-temporal fusion of remote sensing data

湿地植物群落结构及其动态变化特征是反映湿地生态系统健康状况的重要指标,对预测湿地生态系统演变方向和生态恢复至关重要。本文基于融合Landsat和MODIS数据获得的30 m、8 d分辨率的NDVI数据集,结合物候特征构建决策树分类方法,解译了2000-2020年鄱阳湖洪泛湿地植被空间分布格局,分析不同植物群落时空动态特征及转移变化过程。结果表明:遥感时空融合为鄱阳湖湿地植被精细化分类提供了良好的数据基础,基于物候特征的决策树分类方法将研究区解译为水体、泥滩、浮叶植物群落、蓼子草(Polygonum hydropiper)-虉草(Phalaris arundinacea)群落、苔草(Carex cinerascens)群落、芦荻(Phragmites australis-Triarrhena lutarioriparia)群落、蒌蒿(Artemisia selengensis)群落和林地8种景观,总体分类精度达89.36%。从全湖范围来看,湿地植被总面积虽有波动,但整体呈显著增加趋势,其中蓼子草-虉草群落的增加最为明显,而分布最广的苔草群落先增加后有微弱减小,次优势种的芦荻群落面积在300~500 km2之间波动;从不同区域的对比来看,苔草群落在北部和东部湖区的变化趋势较明显,而次优势种的分布存在空间差异,北部和东部湖区主要为蓼子草-虉草群落,南部湖区以芦荻群落为主。此外,在2000-2020年间,鄱阳湖湿地景观演变趋势呈现出从水体→泥滩→低滩地植被(苔草群落、蓼子草-虉草群落)到苔草群落与芦荻群落相互转化的过渡性特征,整体表现出高滩地的芦苇、南荻等植被向低滩地扩张,而低滩地的苔草、虉草、蓼子草等向湖心扩张的态势。;The structure and dynamic characteristics of wetland vegetation communities are important indicators reflecting the health ecosystem, which essential for predicting direction development ecological restoration ecosystem. Based on 30-m 8-day resolution NDVI dataset obtained by fusing Landsat MODIS data, we adopted a phenology-based decision tree approach to map spatial distribution patterns different in floodplain Lake Poyang from 2000 2020, analysed spatiotemporal dynamics transformation processes communities. The results indicated that spatio-temporal adaptive fusion model products (STAFFN) could provide powerful database fine classification Poyang. study area was classified into eight landscapes using approach: water, mudflat, floating aquatic macrophyte community, Polygonum hydropiper-Phalaris arundinacea Carex Phragmites lutarioriparia Artemisia selengensis community forest. overall accuracy 89.36%. Within whole lake, total cover fluctuated, but showed significant increasing trend during observation period. Among communities, most increase, while is widespread, first increased then decreased slightly, subdominant species, fluctuated between 300 500 km2. Comparison sub-lake regions relatively clear northern eastern regions. There were differences species. dominated southern region community. In addition, landscape evolution 2000-2020 transitional characteristic water → mudflat lower flat (Carex community) mutual situation (e.g. australis, Triarrhena lutarioriparia, etc.) higher level expanded towards Carex, Phalaris hydropiper, etc. centre lake.