基于Google Earth Engine的南方滨海盐沼植被时空演变特征分析

Remote Sensing of Spatio-temporal Dynamics of Saltmarsh Vegetation along South China Coast based on Google Earth Engine

掌握滨海盐沼植被时空演变规律是科学开展滨海湿地生态系统管理的基础。滨海盐沼植物互花米草在中国海岸潮间带快速入侵与扩散,显著改变了原有滨海湿地的结构与功能,给滨海湿地保护与管理带来巨大的挑战。目前针对滨海盐沼植被时空动态的大尺度遥感分析还十分有限,人们对滨海盐沼植被空间分布的历史演变规律及其控制机制还缺乏足够的了解。实验基于Google Earth Engine平台和Landsat长时序历史影像,利用连续变化检测和分类算法反演近30 a中国南方(浙江以南)滨海盐沼植被的时空分布,分析潮汐淹水对滨海盐沼植被时空分布的影响。结果表明:①滨海盐沼植被总面积在2000~2004年出现短暂下降,之后呈现持续增长趋势;②滨海盐沼植被面积存在3种增长模式——波动、线性和指数增长;③滨海盐沼植被面积与淹水概率之间近似呈正态分布规律,植被时空分布表现为从低淹水区逐渐向高淹水区扩散的演变趋势。研究结果有助于理解滨海盐沼植被时空演变规律,为滨海湿地的科学管理提供决策支持。

Understanding the spatial and temporal evolution of coastal saltmarsh wetland distribution is the baseofscientific management of coastal wetland ecosystems.Spartina alterniflora has rapidly invaded and spread in the coastal intertidal zone of China,which has significantly changed the structure and function of the native coastal wetlands,leading to great challenges to coastal wetland protection and management.At present,the large-scale remote sensing analysis of the spatial and temporal dynamics of coastal saltmarsh vegetation is very limited,and there is still insufficient understanding of the historical evolution of saltmarsh spatial distribution and its control mechanisms.Based on the Google Earth Engine platform and Landsat imagery,this study usedcontinuous change detection and classification algorithm to obtain the spatial and temporal distribution of saltmarsh vegetation in coastal wetlands in southern China(south of Zhejiang Province)during the past three decades,and then analyzed the impact of tidal flooding on the spatial and temporal distribution of saltmarsh vegetation.The results showed that:(1)The total distribution area of saltmarsh vegetation decreased from 2000 to 2004,and then showed a continuously growing trend;(2)There were three growthmodes of saltmarsh vegetation:fluctuating,linear,and exponential growth;(3)The distribution of saltmarsh vegetation and the frequency of flooding showed a hump-like spatial pattern,and the spatial and temporal distribution of saltmarsh vegetation evolved from less to more inundated area over the intertidal zone.This study helps to understand the spatial and temporal evolution of coastal wetland vegetation and provides decision support for the scientific management of coastal wetlands.