Han, Sang-Kyun. 2006. Impacts on soils from cut-to-length and whole tree harvesting. Dissertation. University of Idaho, Moscow, ID.
A field-based study was conducted to compare the degree and extent of impacts on soils from cut-to-length (CTL) and whole tree (WT) harvesting operations. A CTL harvesting system used less area to transport logs to the landings than did the WT harvesting system (20% vs. 25%). At high soil moisture levels (25 - 30%), both CTL and WT harvestings caused a significant increase of soil resistance to penetration (SRP) and bulk density (BD) in the track compared to undisturbed area (p<0.05). Readings of SRP in the track were consistently higher for all soil depths in CTL units than in the WT units while BD changes were greater in the WT units. There was no significant difference in SRP and BD between the undisturbed area and the center of the forwarding trails in the CTL harvest units (p>0.05). However, in the WT harvest units SRP and BD readings from the centerline area were significantly higher than those from the undisturbed area (p<0.05). Slash covered 69% of the forwarding trail area in the CTL harvesting unit; 37% was in heavy slash while 32% of the trail was covered by light slash. Heavy slash was more effective in reducing soil compaction in the CTL units. Prediction models were developed that can be used to estimate percent increases in SRP and BD over undisturbed areas for both CTL and WT harvesting systems.