Soil physical properties degrade further on skid trails in the year following operations

Short-term recovery of soil physical properties on skid trails was investigated upon cessation of skidding operations and 1 year later. Bulk density and porosity were assessed at three levels of traffic intensity and two slope gradients. Compared to undisturbed areas, bulk density increased, total porosity and macroporosity decreased, and microporosity increased in the compacted areas immediately after skidding. In all cases, changes were significantly greater when traffic intensity was higher and when slopes were steeper. Surface soil compaction did not show any recovery over the 1-year period, illustrating the persistent effects of compaction on soil structure. In fact, surficial compaction further increased and macroporosity further decreased after 1 year of recovery, compared to immediately after skidding. While these changes may reflect inherent small-scale site variability or differences in soil moisture content at times of sampling, direct negative physical impacts on newly exposed soil (such as by raindrops), in addition to the loss of organic matter after canopy removal and skidding, likely delayed any physical recovery, particularly on heavily trafficked trails on steeper slopes. These results raise serious concerns about long-term resilience to traffic on forest soils and indicate the necessity to properly retire skid trails to avoid further soil degradation as trails age.