Abstract
Thinning is one of the most important tools of forest management, although thinning operations require the use of machines which ultimately cause damage to the remaining stand. The level of damage largely depends on the human factor, and a tired, less focused operator will create more injuries in the forest. With this in mind, the objectives of this research were to find out whether the probability of tree damage caused by an operator is also affected by: (1) the part of the day (dawn/day/dusk/night), and (2) the cumulative shift time. The research was carried out in pure pine stands of different ages, density and thinning intensities. Sample plots were selected that had an increasing number of trees per hectare and growing thinning intensities were applied. The same Komatsu 931.1 harvester was used for the thinning operations in each stand. In all the age classes combined, 5.41% of the remaining trees were wounded. There was a significant influence of the part of the day on the percentage of damaged trees, which was positively correlated with the cumulative shift time. Stand conditions, such as age class and stand density, as well as thinning characteristics—thinning intensity, number of harvested trees and productivity—have different effects on the distribution of damage intensity and on probability. The results may improve the planning of operators’ work shifts in forests of various ages and densities, allowing harvester productivity to be maintained while at the same time inflicting the lowest possible level of damage.
Highlights
Modern machines have changed forest operations in the last few decades, increasing productivity rates when compared to manual harvesting
The sample plots were classified according to age class and tree density per hectare (DC)
The reported frequency of the trees being damaged in all the age classes and tree density classes combined was 5.29%, and the damage frequency ranged from 1.12% to 10.92% on the study’s sample plots, suggesting low damage levels
Summary
Modern machines have changed forest operations in the last few decades, increasing productivity rates when compared to manual harvesting. In the last decade, cut-to-length (CTL) technology has replaced manual wood harvesting in many European countries [1]. This increase in the use of harvesting equipment has come about due to a shortage of labor and the need to lower the cost of wood. Previous studies have tried to examine the effect of modified work schedules [9,11,12] and working at different times of the day [16] on operator productivity, as well as the economics of extended shifts and twenty-four seven harvesting [17]
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