Hydraulic properties of Orthic Gray Luvisolic soils and impact of winter logging

Runoff as overland flow and interflow from hillslopes on the Boreal Plain Ecozone of North America is likely to depend on near-surface hydraulic properties. Hydraulic properties were examined in Orthic Gray Luvisolic soil profiles in Alberta. Canada, over several years following clear-cut winter logging and contrasted to those in adjacent forested areas. Infiltration characteristics were determined with double ring infiltrometers at both logged and forested sites. Saturated hydraulic conductivity (K-sat) of Ae and Bt horizons was measured in logged areas with undisturbed Uhland core samples. Infiltration parameters derived by the Kostiakov equation suggest that initial infiltration rates are higher at forested sites than logged. Steady-state infiltration was greater under forest. Vertical K-sat of the Ae was less than the Bt horizon, and horizontal K-sat of the Ae horizon exceeded vertical, indicating anisotropy. Compaction and soil swelling resulting from increased soil water content after logging probably reduced macro-porosity and lowered infiltration capacity. Similarity of K-sat between Ae and Bt horizons in logged areas may have reflected compaction. Logging then may temporarily increase the potential for overland flow but may reduce interflow through Ae horizons until time restores soil hydraulic characteristics to that of an older forest.