Relationships between Soil compaction and harvest season, soil texture, and landscape position for aspen forests

Although a number of harvesting studies have assessed compaction, no study has considered the interacting relationships of harvest season, soil texture, and landscape position on soil bulk density and surface soil strength for harvests in the western Lake States. In 2005, we measured bulk density and surface soil strength in recent clearcuts of predominantly aspen stands (Populus grandidentata Michx. and Populus tremuloides Michx.) in the Chippewa National Forest in northern Minnesota. We stratified these clearcuts by the season harvested, soil texture, and topographic position. In nearly all cases, we observed higher bulk density and surface soil strength following harvesting compared with adjacent and similar but unharvested stands. Within harvested sites, fine-textured soils generally had higher surface soil strength (more compaction) than coarse-textured soils when harvested in the summer, and fine-textured sites harvested in the summer had higher surface soil strength than those harvested in the winter. Landscape position was an important factor only in fine-textured soils. Both summit and toeslope positions had higher surface soil strength following summer harvesting compared with winter harvesting. Overall, our results indicate that fine-textured soils located on both lower and upper slope positions and harvested during unfrozen soil conditions are most susceptible to compaction during logging.