张掖市北郊湿地水生植物多样性及生态健康评价

Diversity and ecological health assessments of aquatic plants inhabiting northern suburb wetland of Zhangye City

水生植物多样性及生态健康评价对湿地生态系统的完整性和稳定性具有重要意义。以张掖北郊湿地为例,通过现场调查与观测、室内测定与分析、数值计算与模拟相结合的方法,开展对水生植物群落、水质指标、湿地健康状况的研究。结果表明,张掖北郊湿地水体质量状况较好,DO、TP、NH_(3)-N及NO_(2)-N含量均值较低,符合Ⅰ类或Ⅱ类水质。而TN、NO_(3)-N及COD含量较高,符合Ⅳ类水质,表明氮素及有机质是湿地水体的主要污染物。水生植物共有14目18科21属26种,且均属于被子植物。单子叶植物共有10目12科15属20种;双子叶植物共有4目6科15属20种,其中,菹草(Potamogetoncrispus)、水葱(Schoenoplectus tabernaemontani)和芦苇(Phragmites australis)的分布范围较广。在25个站位中处于病态的站位共有9个;处于亚病态、临界的站位均为5个;处于亚健康的站位共有4个;处于健康的站位共有2个。从各子系统级别特征值和指标权重可知,影响系统健康的主要因素依次为水质指标、水文指标和水生植物指标。该研究结果对于认识不同水环境因子对水生植物多样性的影响具有重要意义,同时通过湿地生态系统评价为北郊湿地提供有效的管理措施和技术支撑。

Aquatic plant diversity and ecological health assessment are of great significance to the integrity and stability of wetland ecosystem.Taking Zhangye northern suburb wetland as an example,the aquatic plant community,water quality index and wetland health status were studied by combining field investigation and observation,indoor measurement and analysis,numerical calculation and simulation.The results showed that the water quality of the wetland in the northern suburb of Zhangye was good,and the average contents of DO,TP,NH_(3)-N and NO_(2)-N were low,which was in line with Class Ⅰ or Class Ⅱ water quality.The contents of TN,NO_(3)-N and COD were high,which conformed to Class Ⅳ water quality,indicating that nitrogen and organic matter are the main pollutants in wetland water.There were 14 orders,18 families,21 genera and 26 species of aquatic plants,all of which belong to angiosperms.The monocotyledonous plants had 10 orders,12 families,15 genera and 20 species.Dicotyledonous plants consisted of 4 orders,6 families,15 genera and 20 species,among them Potamogetoncrispus,Schoenoplectus tabernaemontani and Phragmites australis have a wide distribution range.Among the 25 stations,9 were in sick condition.There were 5 subpathological and critical stations.There were 4 sub-healthy stations.There were 2 healthy stations.From the eigenvalues and index weights of each subsystem level,we can see that the main factors affecting system health were water quality,hydrology and aquatic plant indexes.The results of this study are of a great significance for understanding the influence of different water environmental factors on aquatic plant diversity,and improving effective management measures and technical support for northern suburban wetlands through wetland ecosystem assessment.