庞泉沟流域土壤粒径分形维数特征

对庞泉沟流域不同海拔人工油松(Pinus tabulaeformis)林、天然油松林、人工华北落叶松(Larix principis-rupprechtii)林、天然华北落叶松林、油松-辽东栎(Quercus wutaishansea)混交林、山杨(Populus davidiana)林、白桦(Betula platyphylla)林、云杉(Picea asperata)-华北落叶松混交林等林种10个典型林分共39份土壤样品的质地、分形维数以及土壤养分进行了研究。结果表明:研究区的土壤质地主要砂质壤土、粉砂壤土、壤质砂土及砂土,其比例分别为46.15%、25.64%、23.08%、5.13%。流域内砂粒、粉粒和黏粒含量平均值分别为62.34%、36.58%、1.08%,粉粒和黏粒变异程度高于砂粒。分形维数介于1.773 3~2.778 9,均值为2.509 0,标准差为0.192 5,土壤质地越粗,土壤粒径分形维数越小。土壤粒径分形维数与土壤砂粒含量呈极显著负相关关系(P0.01),与粉粒含量和黏粒含量均呈极显著正相关关系(P0.01)。流域内不同林分土壤pH值在6.25~8.09,天然林土壤表层有机质、全氮、速效钾含量显著高于人工林,碱解氮含量人工林显著高于天然林,所有林分土壤表层均缺乏有效磷。土壤粒径分形维数与pH呈极显著正相关关系(P0.01),与有机质呈极显著负相关关系(P0.01),与全氮、碱解氮、速效钾呈显著负相关关系(P0.05),与有效磷相关性不显著。分形维数越大,土壤pH越大,土壤肥力越小。因此,土壤粒径分形维数可以作为判断庞泉沟流域土壤质地差异与土壤养分差异的重要指标。

Fractal Dimension Characteristics of Soil Particle Size in Pangquangou Catchment

The soil texture,fractal dimension and soil nutrient contents of 39 soil samples were studied for 8 typical forest stands at different altitudes in Pangquangou catchment.There were 2 plantations and 1 natural forest of Pinus tabulaeformis,2 plantations and 1 natural forests of Larix principis-rupprechtii,Pinus tabulaeformis-Quercus wutaishansea mingled forest,Populus davidiana natural forest,Betula platyphylla natural forest,Picea asperata-Larix principis-rupprechtiinatural forest.The soil texture in the study area are mainly sandy loam,silty loam,loamy sand and sandy soil.The proportions are 46.15％,25.64％,23.08％ and 5.13％ respectively.The average values of sand,silt and clay are 62.34％,36.58％ and 1.08％,respectively,and the variation degree of silt and clay are higher than that of sand.The soil particle size fractal dimension (SPSFD) is in 1.773 3-2.778 9,the average value is 2.509 0,the standard deviation is 0.192 5,and the coarser the soil texture is,the smaller the SPSFD is.From correlations analysis,the SPSFD has a very significant negative correlation with sand content (P＜0.01),and a very significant positive correlation with silt content and clay content (P＜0.01).In this catchment,soil pH value is 6.25-8.09.The soil organic matter,total nitrogen,available potassium content of natural forest were significantly higher than that of artificial forest.On the contrary,the content of alkali-hydrolyzable nitrogen of artificial forest was significantly higher than that in natural forest.All soil sample were lack of effective phosphorus.The SPSFD has a very significant positive correlation with pH (P＜0.01),and a very significant negative correlation with soil organic matter (P＜0.01).And it was negatively correlated with total nitrogen,alkali-hydrolyzable nitrogen and available potassium (P＜O.05).The correlation between the SPSFD and available phosphorus was not significant.The larger the fractal dimension is,the greater the soil pH is,and the smaller the soil fertility is.Therefore,the SPSFD can be used as an important index to judge soil texture and soil nutrient difference in Pangquangou catchment.