宁夏河东沙地生物土壤结皮及其下伏土壤养分的空间分布特征

Spatial Distribution Characteristics of Soil Nutrients of Biological Soil Crusts and Their Underlying Soil of Sandy Land in the East of Yellow River in Ningxia

为了揭示沙地生物土壤结皮的生长发育情况及其下伏土壤养分的空间分布特征,选择宁夏河东沙地为研究区,通过野外采样和室内实验,应用经典统计学、地学统计学和地理系统预测,分析了藻类和藓类结皮及其下伏0-5、5-10 cm土层土壤有机碳(SOC)、全氮(TN)、全磷(TP)含量以及结皮层厚度的空间分布特征。结果表明:(1)SOC、TN、TP质量分数的变异系数(CV)呈中等变异,CV_(TN )(57.1%)>CV_(SOC )(48.7%)>CV_(TP )(30.5%),生物土壤结皮对下伏土壤养分影响显著,其中藓类结皮对SOC和TN的影响更显著,藻类结皮则对TP的影响更显著;(2)藻类结皮下5-10 cm土层TN质量分数呈现强烈空间自相关性,块金系数(N/S)为20.3%,其余土层的SOC、TN、TP质量分数空间自相关性中等,TP质量分数空间变异由随机因素主导,SOC和TN则由结构因素主导;(3)在区域尺度和剖面尺度上,生物土壤结皮及下伏土壤的养分空间分布特征差异显著,结皮层土壤SOC质量分数中部和北部高、南部低,TN质量分数中南部高、西北部低,TP质量分数中东部高、西北部低,均呈条带状分布,0-5、5-10 cm土层SOC和TP质量分数呈中部高四周低的分布特征,TN质量分数呈南部和东部高、西部和中部低的分布特征,SOC与TP形成了典型的“肥岛”,而TN则形成了典型的“水岛”;研究区内TN的空间分布与SOC和TP的空间分布特征不一致,但是与藻类结皮层厚度的空间分布有较高的相似性。这表明,生物土壤结皮能够影响其下伏土壤的养分空间分布。此结果可以为研究旱区荒漠生态系统中生物土壤结皮的生态功能提供数据参考。

In order to reveal the development of biological soil crusts in sandy areas and the spatial distribution characteristics of their underlying soil nutrients,the sandy land in the east of Yellow River in Ningxia Province was selected to be the study area in this research.Analyses pertaining to the spatial distribution characteristics of soil organic carbon(SOC),total nitrogen(TN),total phosphorus(TP)in algal crusts,moss crusts and their underlying 0–5 cm and 5–10 cm soil as well as the thickness of the mentioned crusts were performed,using methods including classic statistics,geostatistics and geosystem prediction after field sampling and indoor experiments.The results showed that(1)the coefficients of variation(CV)of the three nutrient contents all reached the medium level,with CVTN(57.1%)>CVSOC(48.7%)>CVTP(30.5%).Moss crusts had more statistically significant effects on SOC and TN,compared to their effect on TP.The influence of algal crusts on TP was much greater.(2)TN of the soil layer 5–10 cm below the algal crusts showed strong spatial autocorrelation,with nugget coefficients(N/S)being 20.3%.The spatial autocorrelation of SOC,TN and TP in the remaining soil layers was moderate.Spatial variation in TP was dominated by stochastic factors,while that in SOC and TN was dominated by structural factors.(3)In crusts,SOC was high in the north center and low in the south;TN was high in the south center and low in the northwest;TP was high in the east center and low in the northwest.In the 0–5 cm and 5–10 cm layers,the distribution of SOC and TP was high in the center and low in the surroundings,and that of TN was high in the south and east and low in the surroundings.SOC and TP formed a typical“high value zone”,while TN formed a typical“low value zone”.The spatial distribution of TN content was not consistent with the SOC and TP content,but had a high similarity with the spatial distribution of algae crusts layer thickness.At the regional and profile scales,the spatial distribution characteristics of nutrients showed great distinctions in biological soil crusts and underlying soil.This indicates that biological soil crusts can influence the spatial distribution of nutrients in their underlying soils,and the results can provide data for studying the ecological functions of biological soil crusts in dryland desert ecosystems.