Michal Allman, Martin Jankovský, Zuzana Allmanová and Valéria Messingerová
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We observed ground level ozone concentrations on a series of five beech experimental plots, one representing the original stand and the other four generated and modified by cuts of graduated intensity. The study was carried out in a beech ecosystem in the Kremnické vrchy Mts, the Western Carpathian region, in years 1999-2008. The plots, established in 1989, were evaluated and compared statistically before and after the cutting modification in 2004. The level of significance of the effect of this intervention was 99% on the plot representing small-area clear-cut and on the plot treated with medium cut. Differences, though not significant, were also found in the other plots. Apart from the effects due to the stocking reduction, the whole post-intervention period was characterised with the influence of progressively increasing average air temperatures and similarly increasing ozone concentrations. Globally, the ozone concentrations on all plots were lower (average value 39 μg m-3) during the period 1999-2003 than in the following years 2004-2008 (average value 55 μg m-3). Maximum values measured in the growing season ranged from 36 to 140 μg m-3. The allowable limit exceeded 10 times in years 1999-2003 but 17 times in years 2004-2008, implying worsening conditions in Central European beech forest stands.
The modern technological process of timber harvesting is a complex system both technically and organizationally. Nowadays, the study of such systems and improvement of their efficiency is impossible without the use of mathematical modeling methods. The paper presents the methodology for the optimization of logging operations based on the queueing theory. We show the adapted queueing model, which characterizes the process of logging with the use of a harvesting set consisting of harvesters and forwarders. We also present the experimental verification of the designated model that confirmed mode’s adequacy. The analysis of the effectiveness of the investigated harvesting set was conducted and the recommendations for its optimization were drawn. The research was conducted in the Pryazhinsky District in the Republic of Karelia. We showed that significant improvement of operational efficiency of the investigated harvesting set in the study area cannot be done by adjusting separate machine operations (i.e. by reducing the time of operations execution and their steadiness). However, a change in the number of machines allowed significant improvement in the operational efficiency. The most optimal harvesting set design for the experimental area consisted of two harvesters and two forwarders.
Michal Allman, Zuzana Allmanová and Martin Jankovský
Cable yarding is a physically demanding and dangerous occupation in forest harvesting. Currently, the technology is gaining interest due to its low environmental impacts compared to the ground based technologies. This paper was focused on comparing the subjective opinions regarding occupational safety and work environment with objective findings found in the literature. We used a questionnaire with 33 questions, divided into three main parts: (i) personal traits of the participants; (ii) occupation description; and (iii) the occupational risks identified the participants. The sample consisted of 92 workers who operated cable yarders from both the public and the private sector. Our survey showed that 90% of public and 75% of private sector employees view their work as physically very demanding. Regarding risky behaviour, 50% of public, and 54% of private employees stated they risked only when the circumstances forced them to. However, more than 41% of public and 50% of private employees stated they suffered an occupational accident in the last ten years of working with this technology. Considering the workers worked in unstable climatic conditions, on unstable terrain, and the work environment presents other hazards, such as the loads, sharp tools and equipment, this result was not surprising.
There has been an increasing demand for environmental considerations (e.g. unharvested patches) in forest harvest scheduling in the last decades. In Slovakia and the Czech Republic, allowable cut indicators are not based on the spatial structure; thus, they are unable to incorporate these additional conditions. Many harvest scheduling models based on integer and mixed integer programming have been developed throughout the world, but their use in forest management in Slovakia and the Czech Republic is rare. These approaches have mostly been developed for clear-cut management systems and do not exist for shelterwood systems. Harvest scheduling approaches for a two-phase, small-scale shelterwood system and a clear-cut system are presented. The models also include environmental requirements that restrict area of forest stands that are not to be harvested over the planning horizon. A mathematical formulation of that requirement was integrated into the forestry decision support system Optimal to solve all analysed harvest scheduling alternatives for small-scale shelterwood and clear-cut systems. Our results indicated that the total harvest volume amounts could be higher when a two-phase, small- -scale shelterwood system is applied. While there are legal adjacency constraints regulating clear-cut harvests, the influence of additional environmental requirements on the total harvested amount is more restrictive for the shelterwood system because of greater area available for harvest. Both scenarios of maximization of harvested volume and net present value provided comparable results.
Rastislav Raši, Emil Cienciala, Tibor Priwitzer, Štěpán Palán and Pavel Pavlenda
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Lech Płotkowski, Stanisław Zając, Emilia Wysocka-Fijorek, Arkadiusz Gruchała, Jarosław Piekutin and Stanisław Parzych
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Diego Broz, Gastón Milanesi, Daniel Alejandro Rossit, Diego Gabriel Rossit and Fernando Tohmé
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