甘肃小陇山林区不同林分对土壤团聚体稳定性的影响

Effect of Different Forests on the Soil Aggregate Stability in Xiaolongshan Forest Region of Gansu Province

为探究甘肃小陇山不同林分对土壤团聚体稳定性的影响,选取小陇山林区3种典型林分(油松林、日本落叶松林、锐齿栎林)为研究对象,用Le Bissonnais中的快速湿润(FW)处理方法测定其不同土层深度(0—10,10—20,20—40 cm)土壤团聚体平均质量直径(MWD),并进一步研究土壤基本理化性质(土壤机械组成、SOC、CEC、pH)和根系特征(细根与极细根比例、RLD、RMD、SRL)对土壤团聚体稳定性的影响。结果表明:不同林分下土壤团聚体稳定性表现为锐齿栎林>油松林>日本落叶松林。不同土层深度土壤团聚体MWD表现为0—10 cm>10—20 cm>20—40 cm。由一元线性回归模型可知,对土壤团聚体MWD贡献较大的土壤特征因子是CEC(R^(2)=0.55)和SOC(R^(2)=0.54),贡献较大的根系特征因子是RMD(R^(2)=0.60)和RLD(R^(2)=0.45),土壤团聚体稳定性与这4个因子均呈显著正相关(P<0.05)。总体而言,不同林分土壤团聚体稳定性差异不同,团聚体稳定性随土层深度增加而降低,且对土壤团聚体稳定性影响最大的因子是根质量密度。

In order to reveal the effect of different forests on soil aggregate stability in Xiaolongshan forest region of Gansu province,three typical forest stands(Pinus tabuliformis,Larix kaempferi,Quercus aliena var.acuteserrata)were selected as objects of study.The fast wetting(FW)method in Le Bissonnais was used to determine the mean weight diameter(MWD)of soil aggregates in different soil depths(0—10,10—20,20—40 cm),and the effects of soil physicochemical properties(soil mechanical composition,SOC,CEC,pH)and root characteristics(proportions of fine root and very fine root,RLD,RMD,SRL)on soil aggregate stability were further studied.The results showed that the stability of soil aggregates under different forest stands were ranked as Quercus aliena var.acuteserrata>Pinus tabuliformis>Larix kaempfer.Stability of soil aggregates of different soil depths were ranked as 0—10 cm>10—20 cm>20—40 cm.According to simple linear regression models,the soil characteristic factors that contributed the most to the MWD of soil aggregates were CEC(R^(2)=0.55)and SOC(R^(2)=0.54),the root characteristic factors that contributed the most to the MWD of soil aggregates were RMD(R^(2)=0.60)and RLD(R^(2)=0.45),and there was a significant positive correlation between soil aggregate stability and the four factors above.Overall,soil aggregate stability differed in different forest stands,soil aggregate stability decreased with the increasing soil depth,and the factor that influenced the stability of soil aggregates the most was RMD.