连云港市滨海湿地土壤有机碳分布特征及其影响因素

Distribution characteristics and influences of soil organic carbon in the coastal wetland of Lianyungang

滨海湿地作为一种独特的湿地类型,海陆水文循环和生物地球化学循环复杂,有着巨大的固碳潜力,其土壤有机碳的研究对于了解碳循环、气候调节和生态系统健康等方面具有重要意义。在连云港市滨海湿地选取了光滩、碱蓬、互花米草和芦苇4种典型植物类型作为研究对象,分析了不同植物群落土壤有机碳含量的分布特征,并利用Pearson相关性分析、冗余分析(RDA)和结构方程(SEM)等统计方法,探讨了植物群落特征和土壤物理化学性质对土壤有机碳的调控作用,重点解析了滨海湿地环境因子与土壤有机碳含量间的关系。结果表明:在水平方向上,不同植物群落土壤有机碳含量大小依次为芦苇植被带((7.79±4.72) g/kg)>互花米草植被带((7.42±3.14) g/kg)>碱蓬植被带((4.95±3.40) g/kg)>光滩带((3.66±1.90) g/kg)。在垂向上,0~50 cm深度内的土壤有机碳含量的分布呈现随深度增加而降低的趋势;此外土壤有机碳含量和土壤物理化学性质、植物群落特征之间相关性显著,冗余分析结果显示在不同的植物类型中土壤有机碳含量与土壤容重呈负相关,与土壤含水率、植物株高、基径、盖度、地上生物量和地下生物量均呈正相关。结构方程模型表明,土壤含水率是影响滨海湿地土壤有机碳含量的最关键因素。以上研究可为更好地理解滨海湿地的生态系统结构和功能并为全球气候变化相关保护政策的制定提供相关的数据支持。

[Objective]Coastal wetlands,a unique type of wetland with complex hydrologic and biogeochemical cycles,have ignificant carbon sequestration potential.Research on soil organic carbon(SOC)is critical for understanding carbon cycle,climatic regulation,and ecosystem health.[Methods]This study focused on four typical vegetation types grown in the coastal wetlands of Lianyungang,namely,Mudflats,Seepweed,Spartina alterniflora and Reeds.We analyzed the distribution characteristics of soil organic carbon content across different plant communities,and utilized statistical methods such as pearson correlation analysis,redundancy analysis(RDA),and structural equation modeling(SEM)to explore the regulatory effects of plant community characteristics and soil physicochemical properties on soil organic carbon.Particular attention was given to the relationships between environmental factors of coastal wetlands and soil organic carbon content.[Results]Horizontally,the soil organic carbon content of the different plant communities decreased in the following order:Reeds((7.79±4.72)g/kg)>Spartina alterniflora((7.42±3.14)g/kg)>Seepweed((4.95±3.40)g/kg)>Mudflats((3.66±1.90)g/kg).Vertically,the soil organic carbon content decreased with increasing depth within 0-50 cm.Additionally,significant correlations were found between SOC content and soil physicochemical properties,as well as plant community characteristics.The results of the redundancy analysis indicate that soil organic carbon content is negatively correlated with BD(bulk density)in different wetland types but is positively correlated with SWC(soil water content),height,diameter,coverage,AGB(above ground biomass)and BGB(below ground biomass).The structural equation model showed that the soil water content was the most important factor affecting soil organic carbon content in coastal wetlands.[Conclusion]These findings can not only promote a better understanding of coastal wetlands from their ecosystem structure and function but also provide relevant data support for policy making on global climate change.