喀斯特坡地土壤稳渗率空间分布变化特征研究

为查明高异质性背景条件下喀斯特坡地土壤稳渗率空间分布变化特征,在6类典型人为活动方式石灰岩坡地针对4类主要生境类型(土面、土石面、石沟、石缝)开展生境空间分布调查和土壤理化性质分析,并利用Guelph入渗仪进行稳渗率实验。通过对比分析各生境土壤性质和土壤稳渗率关系,结合人为作用方式探讨各生境土壤性质和稳渗率空间变化特征及其演化规律。结果表明:1)喀斯特坡地土壤稳渗率普遍高于非喀斯特地区,喀斯特坡地土壤稳渗率受土壤孔隙和岩石裂隙耦合作用影响。2)各生境条件下土壤稳渗率具有高度的空间异质性,呈现"斑块状"空间分布特征。3)坡地人为作用方式变化将改变原有生境的土壤性质,进而导致各生境土壤稳渗率随人为活动进程发生相应变化。人为踩踏作用影响较小的原生林、次生林和乔灌林坡地土面和土石面生境土壤稳渗率普遍高于石沟和石缝生境,但转变为人为踩踏作用强烈的放牧灌草地或火烧人为干扰地后,土面和土石面生境土壤退化严重,土壤容重和粘粒含量增大,稳渗率显著降低。而石沟和石缝生境土壤性质和稳渗率受影响程度明显小于土面和土石面生境,土壤稳渗率仍可维持较高水平。

Spatial Variation of Soil Steady-State Infiltration Rates in Karst Hillslopes

To find out the spatial variation of soil steady-state infiltration rates in karst hillslopes, the spatial distribution and soil properties of four habitats (soil surface, soil-rocky surface, rocky gully, and stone crevice) were investigated along six karst hillslopes with typical human activities. The soil steady-state infiltration rates were measured by means of a Guelph Permeameter. The statistical results show that:1)the soil steady-state infiltration rates of karst hillslopes are obviously high as compared to non-karst regions, and mainly controlled by soil porosities and cracks of Epikarst coupling; 2) the soil steady-state infiltration rates of four habitats show high spatial heterogeneity and "patch shape" spatial characteristics in karst hillslopes; and 3) transfer of human activities will modify soil properties of habitats, and then change the steady-state infiltration rates. The soil steady-state infiltration rates of soil surface and soil-rocky surface are higher than those of rocky gully and stone crevice in original forest, young forest and mixed arbor and shrub forest with smaller human influence. Soil bulk density and clay proportion of soil surface and soil-rocky surface increase seriously and contrary soil porosity and steady-state infiltration rates significantly decrease when the hillslopes are transformed to burned forest or pastureland. Under the same condition, soil properties and steady-state infiltration rates of rocky gullies and stone crevices affect less significantly than the soil surface and soil-rocky surface habitat, which still have high soil steady-state infiltration rates.