Impacts of Twenty Years Ground-Base Skidding on Physical and Hydrological Soil Properties

Increase in soil bulk density and reduces in porosity and infiltration rate are the most common disturbances during timber harvesting and ground-base skidding. The present study was conducted to study soil physical properties e. g.، soil bulk density، moisture، porosity and soil hydrological properties e. g.، soil infiltration from ground-base skidding in twenty years since logging. After initial survey، four abandonment skid trails were selected with similar pedologic، climatic conditions and physiographic and different age in Necka-Zalemrod catchment in east of Mazandaran province. Results indicated that impacts of machinery traffices in high traffic intensity have remained yet 20 years since logging. Means soil bulk density، porosity and void ratio were 42. 4 greater، 24. 6 and 46. 7 percent، respectively، lower than the undisturbed areas. The least infiltration rate was recorded in 1-5 years old skid trail، so the reduction of water was not considerable within 18 minutes after experiment into soil in inner ring in this skid trail. Results in each skid trail firmed that in low traffic intensity soil physical and hydrologic properties was tent to “normal” recover in compare to the undisturbed areas.