苏干湖湿地土壤全盐含量空间异质性及影响因素

Abstract

土壤盐分的空间异质性是影响湿地植被格局形成和演变的主要因素之一，对于认识内陆盐沼湿地盐分的空间分布及其对环境的响应机制具有重要意义。利用经典统计学、地统计学和Kriging插值等方法研究了苏干湖盐沼湿地浅层剖面0-50 cm土层全盐含量的空间异质性与地下水位埋深、植被覆盖度间的相互作用关系。结果表明：（1）苏干湖湿地0-10 cm、10-30 cm和30-50 cm土层的全盐含量均值分别为204.41、18.62、15.89 g/kg；（2）土壤全盐含量随着土层深度的增加变异性由强变弱，随机空间变异和总异质性程度由高变低，受结构性因素的影响具有强烈的空间相关性，且变程值介于5.2-8.49 km，0-10 cm、10-30 cm全盐含量具有各向异性特征，而30-50 cm的各向异性比接近于1，表现为各向同性；（3）各层土壤全盐含量具有较强的空间异质性，高、低值中心呈斑状镶嵌分布，土壤全盐含量与地下水埋深间呈正相关，与植被覆盖度间呈极显著负相关（P<0.01）。苏干湖内陆盐沼湿地土壤全盐含量空间异质性主要受植被覆盖度的影响，而地下水埋深的变化增加了其空间变异的复杂性，体现了内陆盐沼湿地土壤理化空间系统的复杂性和非均质性。;The spatial heterogeneity of soil salinity is of great significance to understand the spatial distribution of salinity in inland salt marsh wetlands and its response mechanism to the environment. In this paper, the classical statistics, geostatistical, and Kriging interpolation were used to study the interaction between the spatial heterogeneity of the total salt content in the 0-50 cm soil layer of the shallow section the Sugan Lake salt marsh and the depth of the groundwater level and the vegetation coverage. The research area was located in Sugan Lake wetland at the intersection of the Altun Mountains and the Qilian Mountains in the northwest of the Qaidam Basin (94°10'33″-94°14'43″E, 39°01'25″-39°05'32″N), and the elevation is between 2795-2808 m. The results indicates that: (1) the average values of total salt content in the soil layers of 0-10 cm, 10-30 cm and 30-50 cm in the Sugan Lake wetland are (204.41±11.8) g/kg, (18.62±0.92) g/kg, and (15.89±0.81) g/kg, respectively. (2) With the increase of soil depth, the variation of soil total salt content changes from strong to weak. Random spatial variability and total heterogeneity degree change from high to low, which has strong spatial correlation under the influence of structural factors. The range of variation is between 5.2-8.49 km. The total salt content of 0-10 cm, 10-30 cm has anisotropic characteristics, while the anisotropy ratio of 30-50 cm is close to 1, showing isotropy. (3) There is a strong spatial heterogeneity of soil total salt content in each layer, and the high and low value centers distributed in the patches. The total salt content of soil is positively correlated with groundwater depth, and highly significantly negative correlated with the vegetation coverage (P<0.01). The spatial heterogeneity of soil total salt content in inland salt marsh wetland of Sugan Lake is mainly influenced by vegetation coverage. The variation of groundwater depth increases the complexity of its spatial variability, which reflects the complexity and heterogeneity of the soil physical and chemical spatial system of inland salt marsh wetland.