喀斯特槽谷区不同林草恢复模式下土壤入渗特征

为研究不同林草恢复模式对喀斯特槽谷区坡面的水土保持效应,采用野外调查和室内分析相结合的方法,对比分析了喀斯特槽谷区顺、逆向坡面不同林草模式(林地、花椒地、灌草地)下的土壤理化性质和入渗特征。结果表明:(1)顺、逆向坡面下林地容重最小,孔隙度最好,含水率和有机质含量最高,其次是花椒地和灌草地;顺向坡土壤有机质含量显著高于逆向坡(P<0.05),但其他理化指标间差异不显著(P>0.05)。(2)顺、逆向坡面下花椒地入渗曲线较陡峭,而林地、灌草地相对较缓;灌草地入渗率最先趋于稳定(20min左右),而花椒地和林地入渗率在30min左右开始缓慢下降,直到75min以后渐渐趋于稳定;各林草恢复模式下土壤入渗能力均为林地>花椒地>灌草地(P<0.05)。(3)入渗模型中,Horton模型拟合效果最好(R2>0.712),模拟稳定入渗率与实测值间的回归方程决定系数R2高达0.9789。(4)研究区土壤稳定入渗率与总孔隙度、非毛管孔隙度、饱和含水量及pH均呈正相关,而与有机质呈负相关,其中总孔隙度对土壤入渗性能影响最大,有机质影响最小;利用上述指标建立的多元线性回归方程可精确预测土壤稳定入渗率。研究结果可为喀斯特槽谷区坡面植被恢复选择及土壤入渗性能评估提供理论参考。

Soil Infiltration Characteristics Under Different Forest and Grass Restoration Models in Karst Trough-valley Region

In order to study the effects of different forest and grass restoration models on soil and water conservation on the hill slope in Karst trough-valley areas, the physical and chemical properties and infiltration characteristics of soils under different forest and grass patterns (forest land, pepper land and shrub grassland) on the consequent and reverse hill slopes in Karst trough-valley area were compared and analyzed by field investigation and indoor analysis. The results showed that:(1) The bulk density of forest land was the smallest, and the porosity, soil moisture content and organic matter content were the highest, followed by pepper land and shrub grassland. The soil organic matter content of the consequent hill slope was significantly higher than that of the reverse hill slope (P<0.05), but there was no significant difference in other physical and chemical indexes (P>0.05).(2) The infiltration curve of pepper land was steeper both on the consequent and reverse hill slopes, while that of forest land and shrub grassland were relatively slow. The infiltration rate of shrub grassland tended to be stable earlier (about 20 minutes), while the infiltration rate of pepper land and forest land began to decline slowly in about 30 minutes, and became gradually stable after 75 minutes. The soil infiltration capacity of forest and restoration modes on the consequent and reverse slopes was forest land > pepper land > shrub grassland(P<0.05). (3) In the infiltration model, Horton model had the best fitting effect (R²>0.712), compared with Kostiakov and Philip models. The determining coefficient R² of the regression equation between simulated stable infiltration rate and measured value was as high as 0.978 9.(4) The soil stable infiltration rate in the study area was positively correlated with total porosity, non-capillary porosity, saturated water content and pH value, but was negatively correlated with organic matter. Total porosity had the greatest impact on soil infiltration performance, while organic matter had the least impact. The multiple linear regression equation established by the above indexes could accurately predict the stable infiltration rate of soil. The results could provide a theoretical reference for the selection of vegetation restoration and the assessment of soil infiltration performance on the slopes of Karst trough-valley areas.