Investigating the performance of some improvement treatments in restoring soil physical properties of skid trails (Case Study: Darabkola Forest, Sari)

Logging operation by skidders can lead to soil compaction, rutting and erosion of skid trails. Therefore, in order to restore the soil physical properties of skid trails, it is necessary to perform improvement treatments. In this study, four compaction improvement treatments were investigated on one-year-old skid trails with two slope classes of low slope (0-20) and high slope (over 20) and 5 replications. 360 soil samples were taken, half of them before applying the treatments and the other half a year after the treatments application, and were analyzed to evaluate the improvement effect of the treatments. Results of low slope class showed that there was a significant difference between soil bulk density and porosity percentage in improvement treatment plots and control plots of forested area. Treatments of orthogonal groove, diagonal groove and logging residuals showed no significant difference with the control skid trail, and only the use of the combined treatment was able to significantly reduce bulk density and increase porosity percentage compared to the control skid trail. For high slope class, all soil improvement treatments showed a significant difference with control plots; however, compared to the control skid trail, none of the mentioned treatments could cause significant differences. Among the studied treatments, the combined treatment had the best performance in restoring soil physical properties in both low and high slope classes