银川平原草甸湿地盐土及其盐分分布特征

通过野外观测和室内分析,研究银川平原草甸湿地盐土及其盐分的分布特征,根据土壤表层全盐含量将研究区土壤划分为5个等级,分别为Ⅰ、Ⅱ、Ⅲ、Ⅳ、Ⅴ,不同土壤等级的植被类型不同,在土壤Ⅰ中主要分布盐生草本草甸和盐生小灌木草甸,在土壤Ⅱ中主要分布盐生草甸和丛生禾草草甸,在Ⅲ、Ⅳ中主要分布根茎禾草草甸,在Ⅴ中主要分布杂类草草甸和一些低湿草甸;研究区草甸土壤全盐含量在垂直方向上表现出明显的表聚现象,在0~30 cm土层,随着土壤深度的增加,土壤全盐含量急剧下降,在30~70 cm土壤全盐含量的下降则较为平缓;各盐分离子除了HCO_3~–以外,其余各离子均表现出明显的表聚现象,但在不同的土壤等级中,只有Na~+、K~+、Cl~–和土壤全盐的表现一致,均为ⅠⅡⅢⅣⅤ。草甸湿地植物体中也有一定的盐分累积,在植物体中,主要盐分为NaCl、NaHCO_3;在土壤中主要盐分为NaCl、NaHCO_3、Na_2CO_3。

Salt Profile Distributions of Meadow Wetland in Yinchuan Plain

This paper studied the salt profile distribution of meadow wetland in Yinchuan plain based on field observation and analysis in laboratory. According to topsoil salt content soil in the study area was divided into five grades (Ⅰ,Ⅱ,Ⅲ,Ⅳ,Ⅴ) with different vegetation types, mainly salt herb meadows and salt small shrub meadow in theⅠ, salt meadow and grassy meadow inⅡ, rhizome grass meadow inⅢ,Ⅳ, forb meadow and low humidity meadow inⅤ. Total salt accumulated in meadow topsoils. Total salt decreased sharply with the increase of soil depth within 0 – 30 cm depth but slowly with 30 – 70 cm depth. Except HCO3–, other salt ions accumulated obviously in topsoils, Na+, K+, Cl– in different salinization grades shared the same trends with total salt, i.e.Ⅰ>Ⅱ>Ⅲ>Ⅳ >Ⅴ. Meadow wetland plants accumulated salt, mainly were NaCl and NaHCO3, while mainly were NaCl, NaHCO3 and Na2CO3 in soil.