宁南黄土区典型人工林下土壤粒径分布分形特征与养分关系研究

Relationship Between Fractal Characteristics of Soil Particle Size Distribution and Soil Nutrients Under Typical Plantations in Loess Region of Southern Ningxia

以宁夏彭阳中庄小流域3种典型人工林(山杏林、柠条林、沙棘林)为供试样地,以农地为对照,采用野外标准化方法采集0~100cm土壤样品,利用Mastersizer3000型激光粒度仪测定土壤粒径组成,并测定了土壤养分相关参数,研究了3种不同人工林地土壤粒径分布和分形特征及其与养分的关系,以期为宁南黄土区林地土壤健康评价和合理化经营提供参考依据。结果表明:1)3种人工林地0~100cm土层土壤颗粒以粉砂粒为主,其中柠条林和山杏林土壤粘粒含量、土壤分形维数均高于农地和沙棘林。土壤分形维数与土壤各级粒径的差异较大,与粘粒、粉粒呈极显著正相关,与砂粒呈极显著负相关,分形维数越大,所含细颗粒越多;2)3种人工林地在0~100cm土层土壤有机质、全氮、全磷、全钾、碱解氮、速效钾含量差异显著(P<0.05),总体表现为农地>柠条林>山杏林>沙棘林;土壤有机质、碱解氮、速效钾含量随土层深度的增加总体呈下降趋势,均具有明显的表聚性,全氮、全磷、全钾含量随土层深度的变化呈波动性且无明显变化规律;3)土壤分形维数与粘粒、粉粒、全磷、全钾含量呈显著正相关关系(P<0.05),与砂粒呈极显著负相关(P<0.01)。

Taking three kinds of artificial forests(Prunus armeniaca forest,Caragana korshinskii forest,Hippophae rhamnoides forest)in Zhongzhuang small watershed of Pengyang in Ningxia as the sample sites,and the farmland was used as the control,soil samples in 0-100 cm soil layer were collected by field standard method,and soil particle size composition was determined by Mastersizer 3000 laser particle size analyzer.Fractal dimension of soil volume was calculated by fractal geometry method,and soil nutrient related parameters were determined.The fractal dimension of soil particles of different artificial woodlands and their relationship with soil structure and nutrients in the loess region of southern Ningxia were studied,in order to provide reference for the health evaluation and rational management of forest soil in the region.The results showed that,1)the soil grains characteristics of different artificial woodlands were different,the clay,silt,sand and fractal dimension were significantly different among different woodlands(P<0.05).The general pattern of soil fractal dimension was Caragana korshinski forest>Prunus armeniaca forest>farmland>Hippophae rhamnoides forest,which was consistent with the change of clay size.2)The contents of soil organic matter,available nitrogen and available potassium decreased with the increase of soil depth,all had obvious surface polymerization,while the contents of total nitrogen,total phosphorus and total potassium fluctuated with the change of soil depth and had no obvious change rule.The soil nutrient contents of different woodlands were significantly different(P<0.05),and the overall pattern was farmland>Caragana korshinskii forest>Prunus armeniaca forest>Hippophae rhamnoides forest.The contents of soil organic matter,available nitrogen and available potassium decreased with the increase of soil depth,and all showed obvious surface cohesion.The contents of total nitrogen,total phosphorus and total potassium fluctuated with the change of soil depth and had no obvious change rule.3)The fractal dimension of soil was significantly positively correlated with the contents of clay,silt,total phosphorus and total potassium(P<0.05),and was significantly negatively correlated with sand(P<0.01).