A smart thinning operation refers to an advanced method of selecting and cutting trees to be thinned based on digitally captured forest information. In smart thinning operations, workers use the coordinates of individual trees to navigate to the target trees for thinning. However, it is difficult to accurately locate individual trees in a forest stand covered with a canopy, necessitating a precise real-time positioning system that can be used in the forest. Therefore, this study aimed to evaluate the applicability of the global navigation satellite system real-time kinematic (GNSS-RTK) device in a forest stand through analysis of its positioning accuracy within the forest environment and evaluation of the operational range of the single-baseline RTK based on analysis of the positioning precision and radio signal strength index (RSSI) change with increasing distance from the base station. The results showed that the root mean square error (RMSE) of the horizontal positioning error was highly accurate, with an average of 0.26 m in Larix kaempferi stands and 0.48 m in Pinus koraiensis stands. The RSSI decreased to a minimum of −103.3 dBm within 1 km of distance from the base station; however, this had no significant impact on the horizontal positioning precision. The conclusion is that the GNSS-RTK is suitable for use in smart thinning operations.

Two integrated harvesting methods have been primarily applied to increase the opportunity for forest biomass utilization. In Korea, small shovels with a carrier for cut-to-length harvesting (CTL system) and tower yarders for whole-tree harvesting (WT system) are commonly used for the transportation of tree assortments (i.e., sawlogs and logging residue). No previous studies are available in South Korea that have compared and highlighted the operational performance and yield of logging residues between the CTL and WT harvesting systems. Thus, our study’s main objectives were to (1) evaluate the productivity and costs of the two harvesting systems through a standard time study method and (2) estimate the amount of harvesting logging residue at the landing. The productivities of the CTL and WT systems were 1.45 and 2.99 oven-dried tons (odt)/productive machine hour (PMH), at a cost of 86.81 and 45.41 USD/odt, respectively. In the WT system, the amount of logging residue (2.1 odt/ha) collected at the landing was approximately four-times larger than that of the CTL system (0.5 odt/ha). Our results suggested that the WT system is a less expensive and more suitable system when there are markets demanding logs and biomass, whereas the CTL system remains a less expensive option for stem-only harvesting. Furthermore, these results are important for estimating the economic and environmental amount of residue that could be potentially recovered and utilized from the forest types included in the study.

Background: Winch-assisted harvesting is an alternative to traditional cable yarding on steep slopes, offering improved operational efficiency and fewer limitations. Knowledge on the effects of winch-assisted harvesting on soil disturbance are limited. This study aimed to assess the effects of winch-assisted and conventional tracked harvester operations on soil compaction and machine slippage in a clear-cut stand with sandy loam soil. Methods: We evaluated changes in soil physical properties, in depth and extent, along machine operating corridors with and without winch-assist across slope gradients ranging from 30% to 52% and up to three machine passes. Results: The relative increase in bulk density differed between treatments. In the non-assisted corridors, the bulk density increased by 18%, 12%, and 11% at depths of 0–10, 10–20, and 20–30 cm, respectively; the winch-assisted corridors showed smaller increases of 12%, 5%, and 3% at the corresponding depths. The winch-assisted plots did not show a significant reduction in rut depth compared with the non-assisted plots, a result likely influenced by site-specific dry soil conditions. Conclusions: These results highlight the potential of winch-assisted systems to reduce horizontal soil disturbance, though their effectiveness in limiting rutting remains variable under dry conditions.

As the environmental sustainability of forest management has become an increasingly important consideration, incorporating environmental performance into timber harvesting operations has grown to be correspondingly critical. This shift is reflected in a growing move away from large-scale clear-cutting toward smaller-scale harvesting operations. To conduct such small-scale harvesting efficiently, mechanized systems have increasingly been introduced into practice, yet how these systems affect the soil environment relative to conventional harvesting methods remains insufficiently understood. In the Republic of Korea, where steep, mountainous terrain predominates, this knowledge gap is particularly consequential, as the conventional (chainsaw felling and excavator-based woodgrab extraction) system often produces spatially diffuse and severe surface soil damage. This study compared surface soil disturbances between conventional and small-scale mechanized (SSM) harvesting systems across three slope gradient classes (moderate, 25°) at five harvesting units in the Republic of Korea. Disturbance was assessed at total of 2046 systematically distributed grid points using a four-class visual disturbance protocol, with continuous disturbance surfaces derived by inverse distance weighting (IDW) interpolation. The results indicate that SSM systems shift the pattern of disturbance rather than uniformly reducing it. On moderate slopes, SSM (grapple saw felling and clambunk skidding) reduced the proportion of severe, area-wide disturbance but concentrated deep rutting along fixed skid trails, producing significantly deeper ruts than the conventional system. On the steep slope, the SSM system pairing mechanized felling with swing yarder extraction substantially reduced both the extent and the severity of disturbance relative to the conventional system by eliminating in-stand machine travel during extraction. On the very steep slope, no paired conventional unit was available for comparison, but the SSM system using a small tower yarder resulted in a notably low level of surface disturbance. These findings suggest that the soil-protective benefit of SSM systems may depend on how machine traffic is distributed during felling and extraction, offering evidence to guide slope-specific system selection for environmentally sound timber harvesting.