演替梯度下土壤优先流特征及影响因素

Characteristics and Influencing Factors of Soil Preferential Flow in Different Succession Gradients

为揭示植被恢复过程中土壤优先流特征及变化规律,以胡家山小流域内植被恢复过程中5个典型阶段(荒地、草地、灌木、针叶林、乔-灌混合林)为研究对象,采用空间代替时间的方法,通过室内分析和染色示踪试验,分析了演替梯度下土壤优先流特征参数的变化规律,探讨了土壤基本理化性质和根长密度对土壤优先流和土壤水分运移的影响。结果表明:(1)随演替的进行,土壤中优先流数量和运移路径均呈增大趋势;5种演替梯度下针叶林土壤染色面积比最大,其次是乔-灌混合林、灌木、草地,荒地的土壤染色面积比最小;(2)土壤容重、毛管孔隙度、土壤有机质含量与土壤染色面积比之间的相关性较强,砂粒含量、黏粒含量对土壤中优先流染色面积影响不显著;(3)不同径级根系对土壤优先流路径影响不同,5种演替梯度下,D≤0.5 mm的根长密度与土壤染色面积比之间相关性最显著,其次是0.5<D≤2 mm,2<D≤3 mm,3<D≤5 mm;D>5 mm的根长密度与土壤染色面积比之间相关性最不显著。说明土壤容重、毛管孔隙度、土壤有机质含量、D≤2 mm的根系主要影响土壤优先流的产生与发展。

In order to reveal the characteristics and changes of soil preferential flow in the process of vegetation restoration,five typical stages(wasteland,grasslands,shrubs,Platycladus orientalis forest,and mixed forest of arbor and shrubs)of vegetation restoration in Hujiashan Small Watershed were selected.By using the method with space instead of time,indoor analysis and field vegetation survey and dyeing tracer tests were conducted to analyze the variation patterns of soil preferential flow characteristics under different succession degrees,and the effects of soil properties and root diameters on preferential flow and water transport were discussed.The results showed that:(1)with the succession progresses,the number of soil preferential flow and the migration path increased;the soil preferential flow zones were different in the five succession gradients;the soil staining area ratio of Platycladus orientalis forest was the largest,followed by the mixed forest of arbor and shrubs,shrubs,grasslands,and the wasteland was the smallest;(2)soil bulk density,capillary porosity,soil organic matter content,and soil staining area ratio had the significant correlation,while sand content and clay content had no significant effect on preferential flow staining area in soil;(3)different diameter roots had different effects on soil preferential flow paths;the correlation between the root length density of root diameter(D)D≤0.5 mm and the soil staining area ratio was the most significant,followed by 0.5<D≤2 mm,2<D≤3 mm,3<D≤5 mm,the root length density of D>5 mm and soil staining area ratio was the least significant,indicating that soil bulk density,capillary porosity,soil organic matter content,and the root length density of root diameter(D)D≤2 mm mainly affected the generation and development of soil preferential flow.