毛乌素沙地南缘不同固沙灌木下土壤养分的空间异质性

Spatial Heterogeneity of Soil Nutrients under Different Sand-fixing Shrubs in Southern Mu Us Sandy Land,China

土壤养分空间异质性的研究对于土壤管理、生态恢复及可持续发展都具有重要的意义。本文采用描述性统计和地统计学方法研究了宁夏白芨滩国家级自然保护区沙地扎设草方格后种植不同固沙灌木[柠条(Caragana korshinskii)、杨柴(Corethrodendron fruticosum var.mongolicum)、柠条-花棒(Corethrodendron scoparium)混交、柠条-沙拐枣(Calligonum mongolicum)混交和花棒-沙拐枣混交]经长期生态恢复后对土壤养分空间异质性特征的影响。结果表明:研究区土壤有机碳、全氮和速效磷空间分布拟合均符合高斯模型,均有中等程度的空间自相关性,其块金系数分别为0.612,0.612和0.503;速效钾的空间分布拟合为球状模型,具有强空间自相关性,其块金系数为0.887。有机碳、全氮、速效磷和速效钾4种土壤养分呈现出明显的空间分布特征。综上所述,种植不同固沙灌木与沙地土壤养分及其空间异质性之间有一定的关系,含柠条的固沙灌木混交林更有利于沙地土壤肥力的恢复。

The study of the spatial heterogeneity of soil nutrients is of great significance for the soil management,ecological restoration and sustainable development of sandy land.In the present study,methods of descriptive statistics and geostatistics were used to study the effects of planting different sand-fixing shrubs(Caragana korshinskii,Corethrodendron fruticosum var.mongolicum,Caragana korshinskii mixed with Corethrodendron scoparium,Caragana korshinskii mixed with Calligonum mongolicum,and Corethrodendron scoparium mixed with Calligonum mongolicum)with straw checkerboard on the spatial heterogeneity characteristics of soil nutrients after long-term ecological restoration in the sandy land of Baijitan National Nature Reserve of Ningxia.Results indicated that the spatial distribution fitting of soil organic carbon,total nitrogen and available phosphorus in the study area conformed to the Gaussian model,and all of them had moderate spatial autocorrelation,the stractural variance ratio of which was 0.612,0.612,and 0.503,respectively.The fitting model of available potassium followed the Spherical model and had strong spatial autocorrelation,and its stractural variance ratio of which was 0.887.The four soil nutrients(organic carbon,total nitrogen,available phosphorus and available potassium)showed an obvious spatial distribution pattern.In conclusion,there is a certain relationship between different planting modes of sand-fixing shrubs and soil nutrients and spatial heterogeneity in sandy land,among which mixed shrubs containing Caragana korshinskii are more conducive to the restoration of the soil fertility of sandy land.