CHANGES IN PHYSICAL-PROPERTIES OF A SOIL ASSOCIATED WITH LOGGING OF EUCALYPTUS-REGNANS FOREST IN SOUTHEASTERN AUSTRALIA

Logging operations can cause soil profile disturbance and compaction. Soil profile disturbance and compaction change soil physical propertie s, which may reduce site productivity, increase soil erosion and degra de catchment water quality. This study was undertaken to measure the e ffect of logging on physical properties of the 0-100 mm surface soil i n the Victorian Central Highlands, southeastern Australia. Soil physic al properties were measured in the snig tracks, log landings, general logging areas (disturbed areas which were not occupied by snig tracks or log landings) and undisturbed areas. Within the general logging are as? measurements were made for three levels of soil profile disturbanc e: litter disturbed, topsoil disturbed and subsoil disturbed. The resu lts indicated that logging significantly increased bulk density and de creased organic carbon and organic matter content, total porosity and macroporosity on over 72% of the coupe area. However, on 35% of the co upe area, the snig tracks, log landings and subsoil disturbed areas of the general logging area, bulk densities and macroporosities reached critical levels where tree growth could be affected. On these areas, o rganic carbon decreased between 27 and 66%, bulk density increased bet ween 39 and 65% and macroporosity decreased between 58 and 88%. Satura ted hydraulic conductivities decreased to critical levels for runoff t o occur on over 72% of the coupe area (topsoil and subsoil disturbed a reas of the general logging area, snig tracks and log landings). On th is area, the reduction in saturated hydraulic conductivity varied betw een 60 and 95%.