Effects of forest road amelioration techniques on soil bulk density, surface runoff, sediment transport, soil moisture and seedling growth
Although numerous methods have been used to retire roads, new technologies have evolved that can potentially ameliorate soil damage, lessen ,the generation of nonpoint source pollution and increase tree productivity on forest roads. In this study we investigated the effects of three forest road amelioration techniques, subsoiling, recontouring and traditional retirement (control treatment), on soil bulk density, surface runoff, sediment production, soil moisture and seedling growth. As a point of comparison, surface runoff, sediment production and soil moisture was also measured on relatively undisturbed forested reference sites. The recontoured treatment had significantly lower bulk densities, surface runoff and sediment production than either the subsoiled or control treatments. The relatively undisturbed reference sites had very little runoff and hence, very low sediment production. Reference sites also had generally lower soil moisture at 0-2015 and 15-25 cm than above, within and below the treatment road sections. Among treatments, few differences were found in soil moisture among treatment:landscape position combinations. Recontoured and subsoiled treatments had significantly greater white pine diameter growth than control plots. Yellow-poplar diameter and height growth was greatest for recontoured plots followed by the subsoiled plots and the control plots. The combination of data indicates that the use of recontouring techniques on forest roads generally leads to lower bulk densities, less surface runoff and sediment production and greater seedling growth than both traditionaI and subsoiling road retirement methods, however, the cost of recontouring is greater than subsoiling or traditional retirement and the preliminary analysis indicates that subsoiling may represent the most economically viable retirement method.