银川平原草甸湿地表层土盐分累积特征

银川平原湿地属于典型的绿洲湿地,不仅是生物多样性的载体,还有具有重要的环境调节功能及较高的生产力,但由于其地处于易发生盐分累积的区域,因此,找出银川平原草甸湿地土壤盐分的空间累积特征,对了解银川平原水盐迁移过程对湿地生态系统的影响十分重要。该文采用野外调查、室内分析的方法,研究了银川平原草甸湿地植被的分布特征,草甸湿地土壤盐化等级的划分,盐分累积状况,该研究共设置样地57个,样方123个,根据传统的分类方法将研究区植物群落划分为3个植被型,8个植被亚型,27个群系。根据土壤表层全盐含量0~20 cm,把研究区土壤划分为5个等级:Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ,它们对应的含盐量分别为≥10、4~10)、2~4)、1~2)和1 g/kg。银川平原草甸湿地土壤盐分呈自南向北逐渐增加的空间变化;不同草甸植被类型的含盐量大小为盐生草甸典型草甸湿生草甸;不同地形部位草甸的盐分含量表现为干湖滩洪泛平原堤外湖滩湿湖滩渠边沙滩,地下水埋深和水盐循环过程是盐分分布特征的决定性因素。

Salt accumulation characteristics of topsoil in meadow wetland in Yinchuan plain

Belonging to typical oasis wetlands in China, the wetland of Yinchuan not only is the barrier of biodiversity, but also plays a crucial role in environmental regulation and productive improvement. Unfortunately, it is prone to salt accumulation in the wetland. Therefore, it will be of great significance for having a good knowledge on the impact of the process of water and salt migration on wetland ecosystem to find out the spatial accumulation characteristics of soil salinity in the meadow wetlands in Yinchuan Plain. This paper uses the field survey and laboratory analysis methods to research the distribution of vegetation, the classification of soil salinization and the situation of salt accumulation in the meadow wetlands in Yinchuan Plain. In this study, we set up 57 experimental plots with 123 points, and the plant communities in the study area are divided into 3 vegetation types, 8 vegetation subtype s and 27 formations according to the traditional classification. A total of 44 species of plants are investigated, which is a relatively small number; according to the investigation results on the plant communities in ditch wetland in the Yinchuan Plain by Cheng Zhi, the investigated plants reached a total of 87 species, belonging to 31 families and 71 genera, and the plants along ditch slope were divided into hygrophyte, mesophyte and halophyte with plants in ditch base. On the basis of the soil surface salinity (0-20 cm), the soil in the study area is divided into 5 grades:Ⅰ,Ⅱ,Ⅲ,Ⅳ andⅤ, and the corresponding salt contents are≥10, 4~10), 2~4), 1~2)和<1 g/kg, respectively. The results show that soil salt content increases from south to north in the meadow wetlands in Yinchuan Plain. Salinity of different kinds of vegetation meadows is in a descending order as follows: salty vegetation, typical meadow and wet meadow. And Salinity in different topographical meadows is dry lake beach > floodplain > lake beach outside river levee > wet lake beach > sand beach. Buried depth of groundwater and salt-water cycle process are the decisive factors of salt distribution characteristics. Behind the large-scale wetland restoration in Yinchuan Plain, there is a hidden risk of land salinization in the lakeside zone, and if there is no good artificial recharge of irrigation and drainage vent of salt leaching, the natural restoration vegetation in lakeside meadow will be salt meadow or salt shrub. The vegetations artificially planted also have the problems of the accumulation and degradation of soil salinity. The study on the spatial accumulation characteristics of soil salinity in the meadow wetlands of Yinchuan Plain were found out is helpful to understand the biogeochemical cycle, source and sink effect in wetland ecosystem, reveal the salt accumulation effect and its distribution characteristics in the process of wetland development in Yinchuan Plain, and further understand the effect of water and salt migration process of wetland ecosystem in Yinchuan Plain. The results provide the scientific guidance to the lakeside and bank afforestation and ecological construction and to wetland comprehensive utilization, especially wetland grassland construction.