(2014). Sequencing of harvester work during standard cuttings and in areas with windbreaks. Silva Fennica vol. 48 no. 4 article id 1159. 16 p. Highlights• In standard cutting stands and thinning areas with windbreaks there occurred three-activity operational cycles. In mature stands with windbreaks the occurrence of stable sequences supplemented with five-activity cycles was noted. Consequently, the operational time in post-disaster thinning stands should be increased by 55% whereas in mature stands it should be 30% longer in comparison with standard stands. AbstractThe aim of the study was to characterize repetitive cycles of harvester operation. The study was conducted in thinning, mature and post-disaster pine stands. The sequences of the activities characteristic of harvester operation were described as time series. In order to detect the cyclic variable structure of the analysed time series, the methodology of the single spectrum Fourier analysis was applied. In standard stands, post-disaster late-thinning stands and mature stands, the existence of stable operational cycles with the length of three activities was discovered while in post-disaster mature stands additional five-activity operational phases were noted. Described in this way, the lengths of the operational cycles of harvesters working in post-disaster areas were higher by about 55% and 30% respectively, as compared to standard thinning and mature stands.

Blue stain is a type of discoloration that considerably lowers the aesthetic qualities of wood. During harvesting, fungal inoculum finds its way into the wood through places of cutting, delimbing, and damage to the tree stem. The development of peripheral blue stain in the logs of Scots pine (Pinus sylvestris L.) due to damage by a harvester head was investigated, using logs felled and delimbed with a chainsaw as reference. The development of blue stain was related to the age class of the stand, the date of felling, and the microclimatic conditions of the wood storage place. The mean surface area of blue stain in logs produced with the harvester was almost 35 cm2, approximately 30% larger than that of the reference logs. In stands of the fourth age class (diameter at breast height 32 cm), the surface of blue stain was more than two times larger than that of stands of the third age class (diameter at breast height 24 cm). The mean area of blue stain in wood stored after spring felling (19.3 cm2) was about 50% of that after summer felling (38.2 cm2). In particular, the development of blue stain in logs obtained with a harvester was visible between weeks 6 and 9 after spring felling and between weeks 3 and 6 after summer felling. For both felling dates, the range of blue stain depended less on air temperature around the wood stack and depended more on the duration of storage.

The aim of the study was to determine the mental workload of a harvester operator when working in late thinning and in windthrown stands of the same type and age, using eye movement patterns as an indicator. Eyeball movement variability was analysed using the eye tracking method. The mean duration of eyesight fixations in windthrown stands was shorter than in the control undamaged stands by about 20% (444 ms and 534 ms, respectively). The mean time of eyesight movements (saccades) in the windthrown stands was shorter than in the control undamaged stands by approx. 15%. The largest differences between the duration of saccades in the windthrown and control stands were observed between the cutting of trees and cutting logs off their root plates: the saccades were longer by about 20% when working in the control stands (49 ms) as compared to the windthrown stands (43 ms). Large differences in the duration of saccades between the windthrown area (42 ms) and the control area (47 ms) were also found when travelling between successive operation sites. In both types of stands, the shortest saccades were observed during processing: 39 ms. Summary durations of saccades observed during the processing of successive trees occurred in sequences showing repeated periods of variable eyeball activity, where longer saccades were followed by shorter ones. Documented more variability of eyesight activities of the harvester operator performing the operations of processing and moving is new standard of eye balls activities for the more taxing work conditions presented by windthrown stands.

The aim of the present work was to estimate the productivity and costs of timber harvesting and forwarding during the first commercial thinning of a Scots pine stand. Three harvesting models were introduced and compared: narrow trail, wide access trail, and schematic extraction. The analyzed harvesting equipment consisted of a track mini-excavator (34 kW) with a stroke harvester head (gripping range 4–30 cm), and a farm tractor coupled to a logging trailer with a hydraulic crane. Merchantable timber (roundwood with a minimum diameter of 5 cm inside bark) was harvested from a 25-year-old planted Scots pine stand growing on a grid of 1.4 m × 1.8 m. The study showed the productivity of the mini-harvester ranged from 3.09 to 3.47 m3/PMH15 (productive machine hours plus 15 min), and that of the forwarding equipment to be 4.07 m3/PMH15. The analyzed model of productivity as a function of tree volume and thinning intensity was statistically significant, but the intensity parameter was significant only on plots located along wide access trails (3.7 m) and insignificant on plots located along narrow access trails (2.5 m). The distance between trees was not found to be significant. The calculated net machine costs for the forwarding equipment and track mini-harvester were EUR 36.12 and 52.47 per PMH, respectively. An increase in the usage rate of the harvesting equipment to 80% would reduce the harvesting and forwarding costs to EUR 22.07/m3.

In 1992, in Southern Poland, large areas of Silesian forests were affected by the country’s largest forest fire. Stands introduced in the 9000-ha post-fire region are currently undergoing early thinning. Due to the scope of these treatments, the chance for their timely implementation is ensured only by the application of cut-to-length (CTL) technologies, i.e., with the use of harvesters and forwarders. The use of CTL technologies may, however, be difficult due to the fire history of these stands, which could affect the bearing capacity of their soils. The objective of this study is to determine the accessibility of stands for forest machines in relation to the bearing capacity of the soils and changes in soil compaction in the post-fire sites. Soil compaction was measured in terms of penetrometer resistance in the stands introduced in the post-fire area in question, as well as in control stands growing on five different soil types. It was shown that in the topsoil layer—from 8 to 18 cm thick depending on the soil type—differences in soil compaction in the post-fire and control areas were relatively small. The impacts of the forest fire—manifested as a significant increase in the compaction of the forest soils—were still visible, but only in the deeper layers of the soil profile. In all of the compared pairs of forest compartments located in the stands regenerated after the fire, significantly higher values of cone indexes (CI) were found. The average value of this index in the post-fire stands was 2.15 MPa, while in the control stands it was 1.60 MPa, which indicates that in both groups of stands the bearing capacity of the soils should not limit the accessibility for vehicles used for timber harvesting and extraction.