北江干流河岸带不同植被类型土壤粒径分形特征

Fractal Characteristic of Soil Particle Size Under Different Vegetation Types in Riparian Zone of the Main Stream of Beijiang River

结合野外调查与室内试验,以北江干流河岸带竹林、桉树林、混交林和草地土壤为对象,对比分析了不同植被类型土壤的颗粒组成与分形维数(D)特征及其与其他土壤理化性质的相关性。结果表明:北江干流河岸带土壤结构良好(D=2.79),质地均一,粒径分布均匀(粉粒、砂粒、黏粒百分比分别为40.66%,36.59%,22.75%),但随粒级增大,空间变异增强;D值与土壤颗粒组成显著相关,随黏粒和粉粒含量升高、砂粒含量降低,D值升高;不同植被类型土壤分形与颗粒组成差异明显,其中砂粒含量表现为竹林>混交林>草地>桉树林,D值、粉粒和黏粒含量均表现为桉树林>草地>混交林>竹林,竹林和桉树林对土壤结构的影响差异有显著(p<0.05),其他植被类型影响差异不显著;D值、黏粒含量均与硝态氮(NO-3-N)和全磷(TP)含量分别呈显著负相关和显著正相关(p<0.05)关系,土壤砂粒含量与含水量(SM)呈显著负相关(p<0.05),土壤粉粒含量只与SM呈显著正相关,另外,D值、砂粒、粉粒和黏粒含量与总有机碳(TOC)和全氮(TN)的相关性均不显著。河岸带土壤受多种因素影响,其土壤理化性质间的相互关系与其他景观差异明显。

Taking 4kinds of vegetation types such as bamboo forest,eucalyptus forest,mixed forest,and grassland as research samples,we investigated the soil particle size distribution（PSD）and fractal dimension（D）characteristics as well as their relationships with other basic soil physicochemical properties based on the field survey and laboratory experiment.The results indicated that soil structure in Beijiang River riparian zone was good with Dvalue of 2.79,soil texture was uniform,and the soil PSD was homogeneous with silt,sand,and clay contents of 40.66%,36.59%,and 22.75%,respectively.However,spatial variation of soil particle increased with increase of soil particle size.Pearson correlation analysis indicated that D value was significantly related with PSD,namely,Dvalue increased with increase of silt and clay contents and decrease of sand content.Dvalue and PSD varied obviously between different vegetation types,therein,the sand content followed the order of bamboo forestmixed forestgrasslandeucalyptus forest,while the D value,silt content,and clay content presented the same change rule,in the order of eucalyptus forestgrasslandmixed forestbamboo forest.Moreover,ANOVA result showed that,with regarding to effect of vegetation type on soil structure,there was significant difference between bamboo forest and eucalyptus forest,while insignificant deference between other vegetation types was observed.Relationship between Dvalue and PSD and other soil physicochemical properties showed that both Dvalue and clay content were correlated signifi-cantly and negatively with nitrate nitrogen content（p0.05）and then were correlated significantly and negatively with total phosphorus content（p0.05）.Soil sand content was significantly negatively correlated with soil moisture content at the 0.05 level,and then soil silt content was only significantly negatively correlated with soil moisture content.In addition,the correlations between Dvalue,sand,silt,clay contents and total organic carbon and total nitrogen contents were not significant.In summary,riparian soil is influenced simultaneously by various factors,and the relationship between its physicochemical properties is significantly different from the other landscape.