科尔沁沙地樟子松人工林土壤粒径分布特征

Soil particle size distribution of Pinus sylvestris var.mongolica plantations in the Horqin Sandy Land

为揭示科尔沁沙地不同林龄沙地樟子松人工林对风沙土粒径分布特征的影响,以中龄、近熟和成熟沙地樟子松人工林风沙土为研究对象,以裸沙地风沙土为实验对照,采用激光衍射技术测定.土壤样品粒度组成,计算分析土壤粒度参数特征,绘制土壤粒配曲线。结果显示:(1)科尔沁沙地樟子松人工林风沙土以砂粒为主,其次是粉粒,黏粒含量最少。随林龄的增长,土壤黏粒、粉粒含量呈增加趋势,砂粒含量呈减少趋势。裸沙地风沙土砂粒含量多高于同层林地土壤。(2)科尔沁沙地樟子松人工林风沙土质地较粗,分选性较差,偏度值多为正偏度,峰度值多为尖窄,0~10cm和10~20 cm风沙土分形维数分别为2.18~2.43和1.98~2.17。裸沙地风沙土质地更粗,分选性更好,分形维数更小。(3)科尔沁沙地樟子松人工林风沙土的粒度频率分布曲线均为双峰型。随林龄的增长,10~20cm.风沙土的土壤颗粒细化滞后于0~10cm。林地悬移组分的含量高于裸沙地,裸沙地跃移组分的分选性高于林地。科尔沁沙地不同樟子松人工林风沙土粒径分布特征存在显著差异,本研究结果可为科尔沁沙地土地沙漠化防治及生态修复提供理论依据。

In order to reveal the effects of different Pinus sylvestris var.mongolica plantations on the soil particle size distribution(PSD)in the Horqin Sandy Land,Inner Mongolia,China,we collected aeolian soil samples of middle-aged,near-mature,and mature plantation,as well as of bare sandy land.The PSD was determined by using a laser diffraction technique.The soil particle size parameters and the grading curve of different plantation types were then calculated and analyzed.The results indicated the following:(1)The soil PSD in the Pinus sylvestris var.mongolica plantations in the Horqin Sandy Land demonstrated the prevalence of sand,followed by clay and silt.With the development of the plantations,we noted an increase of the clay and silt fractions,paralleled by a decrease of the sand fraction.Basically,the sand content of the bare sandy land outweighed that of the plantation soil at the same layer.(2)The plantation soil PSD reflected a poor sorting;moreover,it had a positive skewness and a sharp kurtosis,suggesting the prevalence of coarse particles.The fractal dimensions of the plantation soil between 0-10 cm and 10-20 cm were in the range of 2.18-2.43 and 1.98-2.17,respectively.Overall,the soil texture,sorting,and fractal dimension of the bare sandy land were inferior to those of the plantations.(3)The frequency curve of each plantation showed two peaks.With the development of the plantations,the structure of the soil layer between 0-10 cm was refined faster than that between 10 and 20 cm.The content of suspended components in the plantations was higher than in the bare sandy land,while the sorting of the jump components was less optimized.The results of this study,which include the characteristics of soil PSD in different types of Pinus sylvestris var.mongolica plantations in Horqin Sandy Land,can be applied to contrast the desertification process affecting the study area and to ecological restoration.