Clear-cut forest harvest impacts on soil quality indicators in the mixedwood forest of Saskatchewan, Canada

Abstract

The concept of soil quality is relevant to a range of human-induced disturbances on soil; our objective was to examine the impact of clear-cutting on soil quality conditions in six Mixedwood ( Populus tremuloides-Picea glauca) stands in Central Saskatchewan, Canada. Soil quality conditions at two short-term (1 to 5 years) and four medium-term (6 to 20 years) clear-cut sites were compared to eight mature Mixedwood sites. All sites had a similar, albeit complex, distribution of soil and parent sediments. No major differences were observed between the short-term clear-cut sites and the mature Mixedwood sites. At the medium-term sites, substantial losses of soil organic carbon (24%), soil nitrogen (27%), and LFH thickness (28%) were observed, along with decreases in the soil surface (0 to 15 cm layer) of exchangeable calcium and magnesium (30%), soluble organic P (15%), and cation exchange capacity and base saturation (20%). The losses were much lower in the 15 to 45 cm layer of the soil. Overall, the levels of these soil components observed at the clear-cut sites were within the natural or undisturbed range as assessed at the mature Mixedwood sites; however the amounts of soil organic carbon and nitrogen at the clear-cut sites were lower than the natural range. Although the absolute levels of loss of soil organic carbon and nitrogen were much lower than in typical agricultural landscapes, the long-term ecological significance of the losses in these forested landscapes remains a concern.