Abstract:The objective of this paper is to reveal the influence of human trampling on infiltration characteristics of various forest soils in karst mountain lands. Inside the forest, central areas of forest path, edge areas of forest path, and bare lands were selected as test plots. The unsaturated hydraulic conductivity (K9, K6, K3, K0.5), saturated hydraulic conductivity Ks, contribution rate of water flow and Gardner α were determined via disc infiltrometers under different pressure heads (-0.5, -3, -6, -9 cm). The dye coverage (DC), uniform penetration depth (UniFr) and preferential flow percentage (PF-fr) were estimated through in-situ dye tracer experiments and digital image processing. Based on a series of dye tracer experiments, the effects of human trampling on the soil preferential flow were analyzed. The results showed that the KS values in central areas of forest path (45.800×10-3 cm/min) was 55% lower than that of the inside the forest (101.000×10-3 cm/min). The drastic reduction in values of the Gardner α and the soil pores number explained the reduce of soil infiltration capacity in forest paths. The percentage of preferential flow in the center areas of the forest path (71.955%) was significantly higher than that in the forest lands (36.734%), and this result indicated that the soil preferential flow was largely enhanced by trampling activities from humanity. The average contribution rate of water flow exceeded 95% in soil macro-pores under the four levels of artificial trampling. The soil infiltration channels were mainly macro-pores in karst mountain forests. Soil infiltration capacity and soil preferential flow can be effectively enhanced and inhibited by forest vegetation cover. These results can provide an experimental basis to set up a negative list for economic development in karst mountain lands.