盐城滨海湿地退化评估及分区诊断

根据野外监测数据和遥感信息解译结果,分析了盐城滨海湿地生态特征,定量评估了湿地退化程度,分区探讨了导致湿地退化的主导因素。结果表明:①盐城滨海湿地的主要植物为盐地碱蓬(Suaeda salsa)、互花米草(Spartina alterniflora)和芦苇(Phragmitesau stralis)。受湿地基底稳定性和土壤盐度影响,湿地植被呈现出明显的东西分带、南北分区的特点,地带性分布规律明显。②盐城滨海湿地景观类型可以划分为河口水域、盐地碱蓬滩、芦苇沼泽、互花米草沼泽、耕地、建筑用地、养殖池、盐田和光滩9种类型。由于自然因素和人为活动影响,自1980年以后,研究区景观格局发生了巨大变化。自然景观面积减少了33%,人工景观增加了180%。自然湿地中,面积减少最大的是盐地碱蓬滩和芦苇沼泽。③1980～2008年,盐城滨海湿地的互花米草滩面积呈现出增长趋势,盐地碱蓬滩处于严重退化状态,芦苇沼泽处于退化状态,导致盐地碱蓬滩和芦苇沼泽退化的主要因素是人类开发活动。④对不同区域的导致湿地退化的主导因素进行了诊断,其中灌河口—射阳河口岸段湿地退化的主导因素为海岸侵蚀。射阳河口—斗龙港口岸段属于淤蚀过渡海岸,因处于盐城珍禽国家级自然保护区的核心区位置,人类干扰强度不大,湿地退化不严重。斗龙港口—弶港岸段湿地退化的主导因素为人类对湿地的围垦和开发利用活动。

Evaluation of Coastal Wetlands Degradation in Yancheng City and Zonal Diagnosis

Based on the field monitoring data and the results of remote sensing extraction of Yancheng coastal wetlands during 2007-2008,the eco-characteristics,the degree of degradation and the dominant factors of the different zone-area of the wetland degradation were analyzed.The results showed that the predominated vegetation types of Yancheng coastal wetlands are Suaeda salsa,Spartina alterniflora and Phragmites australis.As a result of the stableness of the sedimental environment and the changes of the salt content of the soil,the distribution of the vegetation showed a conspicuous area-zone characteristics.Nine types of wetland landscape were classified of Yancheng coastal wetlands,namely:esturine water,Suaeda salsa flat,Phragmites australis marsh,Spartina alterniflora marsh,cropland,building land,fishery ponds,salt ponds,and barren tidal flat. From 1980 to 2008,the landscape patterns have experienced significant changes.The area of the natural landscapes in Yancheng coastal wetlands decreased by 33%,while the area of the artificial landscapes increased by 180%under the impacts of the natural environmantal changes and human activities.From 1980 to 2008, the area of Spartina alterniflora marsh had an increasing trend,while the area of the Suaeda salsa flat and Phragmites australis marsh were in adverse.The Suaeda salsa flat belongs to serious degradation and the Phragmites australis marsh blongs to degradation respectivly according to the degraded evaluation method. The driving forces of their degradation were the human activities.Three different zone-areas were divided of the study area,and the dominant factors of the wetlands degradation were diagnosed.The segment from the Guanhe esturine to Sheyanghe esturine belongs to abandoned Huanghe River Delt coast,the shoreline have been heavily eroded because of losing of sediments supply,and the dominant factor of the wetlands degradation was coastal erosion.The segment from the Sheyanghe esturine to Doulong Port belongs to erosion-accumulation transition zone,also this segment located at the core area of Yancheng Reserve,the degree of the wetland degradation is not cerious due to effetive protect and slight human disturbance.The segment from the Doulong Port to Jianggang Port belongs to sediment accumulation segment,the dominant factor of the wetlands degradation was human reclamation and exploiting and utilizing activities of the wetland.