艾比湖湿地土壤水分-盐分-养分空间异质性分析

Analysis of spatial variation of soil moisture–salinity–nutrient in Ebinur Lake wetlands,China

为了解艾比湖湿地土壤水分-盐分-养分空间异质性,在环湖一周160 km范围内,以湖心质点为中心,将艾比湖湿地划分为东北、西北、西南、东南4个区域,于2014—2015年5、8月采样,对表层(0～20 cm)土壤含水量、盐分、养分、pH值空间异质性进行研究,结果表明:不同区域土壤盐分、养分、pH值8月高于5月,土壤含水量则相反,其中土壤含水量、盐分、养分属于中等变异,土壤pH值为弱变异;5、8月不同区域土壤盐渍化在中度盐化与盐土化水平之间,pH值呈碱性或强碱性,土壤养分等级较低,总体较为贫瘠。球状模型、指数模型、高斯模型能较好地描述艾比湖湿地土壤空间变异特征,决定系数变化范围为31%～96%;不同区域土壤含水量块金系数小于34%;除5月西南部土壤pH和东北部土壤养分外,不同区域土壤盐分、pH、养分块金系数均小于25%;土壤盐分、pH、养分的Moran′s I(莫兰)系数波动均较大,表明空间相关性较强。从空间上看,5、8月土壤含水量呈带状分布,高值区出现在西北部与西南部,低值区主要在东南部与东北部;土壤盐分高值区主要在西北与东南部,低值区在西南部与东北部;土壤pH高值区主要在西北部及湖周围;土壤有机质、全氮高值区都出现在西北部、西南部,土壤全磷呈无规则斑点状分布,高、低值区较为分散。研究发现,影响艾比湖湿地空间异质性的因素中,土壤盐分、pH、养分主要受结构性因素影响,土壤含水量受结构性因素和随机性因素共同影响。

To study the spatial variation of soil moisture–salinity–nutrient in Ebinur Lake wetlands, the wetlands were divided into 4 regions,northeast, northwest, southwest, and southeast, in a circular research area of 160 km2. The temporal and spatial distribution characteristics of soil salinity–nutrient–moisture and pH values in the surface layer(0~20 cm)were studied in May and August in 2014 and 2015.The results were as follows. The soil salinity, nutrients, and pH in different regions were higher in August than those in May, whereas the soil moisture content was the opposite. The soil moisture, salt, and nutrient contents were moderately variable, and the soil pH value wasweakly variable. The soil salinization conditions in different regions in May and August were between moderate salinization and saline level. The pH value was alkaline or strongly alkaline, and the soil nutrients were generally poor. The spatial variability of the soil in Ebinur Lake wetlands could be well-described by the spherical, exponential, or Gauss model, and the coefficient of variation ranged from 31% to96%. The nugget coefficients of soil water content were less than 34% in different regions. In addition to the soil pH in the southwestern region in May, and the soil nutrients in the northeast region, the nugget coefficients of soil salinity, pH, and nutrient in different regions were all less than 25% in May and August. The Moran′s I coefficients of soil salinity, pH, and nutrient fluctuated greatly, indicating that the spatial correlation was strong. The soil moisture contents in May and August were distributed in strips.The high-value areas appeared in the northwest and southwest, and the low-value areas mainly in the southeast and northeast.The soil-salinity high-value areas were mainly in the northwest and southeast; the low-value areas were in the southwest and northeast. The soil-pH high-value areas were mainly in the northwest and around the lake. The distributions of the soil organic matter and total nitrogen had certain similarities, and the high-value areas appeared in the northwest and southwest. The total phosphorus content in the soil was irregular and spot-like, and the high and low values were scattered. It was found that the soil moisture content was influenced by both the structural and random factors, and the soil salinity, pH, and nutrients were mainly affected by the structural factors in the Ebinur Lake wetlands.