The goal of this study was to determine the suitability of optical heart rate sensors for forwarder driving heart rate measurement. In the forestry and Forest Products Research Institute, a circuit with straight lines and curves (curve radius of 6 m and 8 m) was installed, and forwarder driving experiments were conducted for three participants. The Apple Watch (Apple Inc.), a wristwatch-type optical heart rate sensor, and myBeat (WHS-1, Union Tool Co.), a chest-worn electrocardiogram monitoring device, were used to measure heart rate. Furthermore, in this test, the labor load was equivalent to driving on forest roads with an empty 2-ton truck, which was less than forwarding including loading and unloading. The average of the measured differences between the two sensors was −0.51 bpm. As a result of the Bland-Altman analysis. Because more than 99% of bias measurements were within ±20% of the mean, it was discovered that the optical heart rate sensor can produce results as accurate as a conventional electrocardiograph. As a result of the time series analysis, Apple Watch was able to obtain the structural change in heart rate, and it was thought that it could be effective for detecting labor burden.

In this study, the tension in the skyline and guyline as well as the load under the hook and that on the tires and outriggers of a medium-range tower yarder during uphill yarding was measured. Furthermore, we evaluated the safety and estimated the working capacity of the machine. After analyzing 16 cycles, for which the load under the hook was measured, results indicated that the maximum load volume based on the safety factor of the mainline and skyline was 1.51 and 1.74 m³, respectively. Thus, 1.51 m³ was estimated to be the load volume limit of the machine used in this study. The highest loading volume per cycle was 1.55 m³, and yarding was generally performed safely during the test. However, during lateral yarding, the tension in the loaded mainline was equivalent to the maximum pulling force regardless of the loading volume. Therefore, the guyline tension and outrigger load were within the safety limits, but the increase in tension of the guyline against the tension in the skyline was low because the guyline was stretched nearly horizontally in this case. When the elevation angle of the antechamber is approximately 45°, the safety factor may become less than 4, and the load on the road surface at that time was approximately 1.7 times greater than when the antechamber was horizontal. Therefore, the greater the elevation angle of the antechamber, the greater the load on the antechamber and road surface.

To clarify the harvesting costs associated with final cutting in Japanese cypress shelterwood stands, we observed four final cutting cases in Nagano Prefecture, Japan. All final cuttings were performed using chainsaw and heavy machinery. After felling with a chainsaw, heavy machinery was used to produce logs from the felled trees that had reached the forest road network. We analyzed the time consumption for the final cuttings consistently trackable from felling to bunching along the forest road network without forwarding. The average direct cost, calculated from our set unit price, was 4,118 yen per harvested tree, and multiple comparisons using the Games–Howell method showed no significant differences among the study sites at the 5% level. We also estimated direct costs for trees not directly observed in the final cuttings and determined the total harvesting costs incurred at the study sites. Although the harvesting costs were proportional to the number of harvested trees, the amount of the reforestation costs reduced by the understory and the number of harvested trees were uncorrelated. The results suggest that the maximum allowable additional cost for understory varies with forest conditions. Adding the spatial analysis of harvesting systems should clarify efficient final cutting and improve the economics of shelterwood.

We investigated the suitability of six routes for access to ten-ton (10-t) class logging trucks in a rural forest management area located in the Kochi Prefecture. The width of roads, measured on site, was checked against images held on a drive recorder. The radii of the road curves were estimated using interpolation algorithms available in a Geographic Information System application. Necessary road width expansion was calculated by the difference between the actual road width and the width of the Type II Class 2 forest road (3.0 m) added to the extent of widening required for the curve radius. One of the existing routes, which was ascertained to be unsuitable for 10-t class trucks, was found to have significantly lesser necessary expansions to road width, implying that it was originally constructed for lighter 4-t class vehicles. The other routes investigated, including a purpose-built forest road and an upgraded forest road as a prefectural road, were found to be sufficiently wide for accommodating 10-t trucks, although certain sections were significantly narrow in residential areas.