Journal of Forest Science - In Press

Characteristics of the workplace of harvester operators in PolandOriginal Paper

Dominika Gaj-Gielarowiec, Karol Gielarowiec, Grzegorz Szewczyk, Pawe� Tylek

The objective of the presented research was to create an average image of a harvester operator in Poland and to identify factors influencing the degree of mental workload. We used a survey of environmental assessments of workload. The creation of an electronic survey and the support of a company that indirectly employs operators (State Forests) made it possible to reach a large group of surveyed people. The respondents indicated the occurrence of ailments typical of sedentary work at the researched workstation. These included mainly monotony, back pain and numbness in the upper limbs. Stress at work was felt by the majority of respondents, hence the analyses of mental stress, which also translates into other diseases, should indicate key responses to questions regarding comprehensive ergonomic assessments at the researched workstation.

Economic parameters of the natural forest regeneration in changing conditions – a case studyOriginal Paper

Stanislav Novotn�, Josef Gallo, Vil�m Podr�zsk�

Natural regeneration is a crucial factor in improving the economy of forest estates. The presented study analysed the economic parameters of three different approaches to forest regeneration: (<i="">i) artificial regeneration with Norway spruce, (<i="">ii) a 25% admixture of soil-improving and stabilizing species (SSTS), and (<i="">iii) natural regeneration. The expenses for these specific operations related to individual regeneration methods were derived. These variants were investigated before the bark beetle calamity (2014) and after the outbreak (2023) for management sets (MS) 531, 551, 571, and 591, i.e. for acidic, nutrient-rich, gleyed, and waterlogged sites of higher elevations. In all cases, natural regeneration decreased expenses by approximately 50 000 CZK·ha<sup="">–1 to 150 000 CZK·ha<sup="">–1. The 25% admixture of SSTS increased the expenses. The proportion of natural regeneration subsequently decreased due to the bark beetle calamity from roughly 40% to 10% in the recent years, which is comparable with the Czech Republic as a whole.

Stand structural analyses of grey poplar (<i="">Populus � <i="">canescens) stands focused on the expected volume in HungaryShort Communication

Tam�s �bri, Zsolt Keser�, Veronika Honfy, Attila Borovics, K�roly R�dei

Grey poplar (<i="">Populus � <i="">canescens) is a natural hybrid of white poplar (<i="">Populus alba L.) and Eurasian aspen (<i="">Populus tremula L.). It could play a significant role in the afforestation of marginal sites which stretches out on ever more areas due to the negative effects of local climatic change. Based on stand structure analyses of grey poplar stands grown on sandy sites of Hungary, the following relations were found: there is a strong relationship between height and stand volume (R<sup="">2 = 0.7256), as well as between basal area per ha and stand volume (R<sup="">2 = 0.9158). There is a moderate relationship between diameter at breast height and stand volume (R<sup="">2 = 0.6175). The results could contribute to more accurate assessment of applied growing technologies.

Phytochemical screening and phytotoxic activity of <i="">Pinus Ponderosa (Dougl.) LawsonOriginal Paper

Mouna Souihi, Marwa Khammassi, Habiba Kouki, Ismail Amri, Mohsen Hanana, Lamia Hamrouni, Yassine Mabrouk

Developing natural herbicides offers a potential solution to mitigate the drawbacks associated with synthetic pesticides used in an excessive quantity to safeguard agricultural crops. In this study, essential oils extracted via hydrodistillation from <i="">Pinus Ponderosa needles were investigated for their chemical composition and phytotoxic activity. Gas chromatography with mass spectrometry detection (GC/MS) identified twenty-three constituents, constituting 93.87% of the total oil. The predominant components were oxygenated monoterpenes (64.66%), with α-pinene (37.78%), β-pinene (24.32%), and sesquiterpenes hydrocarbons, particularly germacrene-D (7.26%). The phytotoxic effects of <i="">P. ponderosa essential oil were tested on <i="">Phalaris canariensis L., <i="">Trifolium campestre Schreb., and <i="">Sinapis arvensis L. The essential oil exhibited a significant inhibitory effect on seed germination and seedling growth in a dose-dependent manner. A low concentration of essential oil reduced the germination and seedling growth of all tested weeds. Additionally, the essential oil treatment impacted malondialdehyde content and electrolyte leakage in the seedlings. These preliminary findings suggest that essential oils from forest trees, particularly <i="">Pinus ponderosa, could serve as an eco-friendly alternative to chemical herbicides. This approach may contribute to addressing the challenges associated with synthetic pesticides while promoting sustainable and environmentally friendly agricultural practices.

Mechanical and physical properties of three eucalyptus spp. clones planted in ThailandOriginal Paper

Trairat Neimsuwan, Kitipong Tangkit, Chakrit Na Takuathung, Nopparat Kaakkurivaara, Ponthep Meunpong, Narinthorn Jumwong, Pattama Sangvisitpirom, Tomi Kaakkurivaara

Eucalyptus plantations are an important source of raw materials for the Thai forest products industry. Despite its economic value, only a few noncomprehensive papers have been published about the wood properties and fungal susceptibility of eucalyptus. Our study covered the most commonly used commercial eucalyptus clones with a wide variety of sizes from eastern Thailand. We assumed that the properties of the clones would differ based on the tree sizes. The objectives of this study were to determine the effects of diameter at breast height (<i="">DBH), size, and clone type on wood properties and mould susceptibility. The optimal usage of each log characteristic based on the log quality and properties could be used to determine the maximum payoff. The wood properties and log characteristics of five eucalyptus log classes with three clones were investigated. In general, the levels of means and standard deviations were following: the modulus of rupture (<i="">MOR) was between 39 ± 4.9 MPa and 66 ± 5.4 MPa, and the modulus of elasticity (<i="">MOE) was between 14.5 ± 9.7 GPa and 24.0 ± 2.7 GPa. In addition, the compression parallel to the grain was between 28 ± 3.2 MPa and 43 ± 2.4 MPa, and the compression perpendicular to the grain was between 13 ± 0.7 MPa and 19 ± 1.1 MPa. The shear strength parallel to the grain was between 10 ± 0.3 MPa and 14 ± 0.6 MPa. The cleavage and hardness were 4.7 ± 1.6 N – 7.4 ± 0.9 N and 3.6 ± 0.3 kN – 6.2 ± 0.6 kN, respectively. The toughness and nail withdrawal were 27.3 ± 3.5 kN·mm<sup="">–1�– 50.5 ± 1.0 kN·mm<sup="">–1 and 28.56 ± 4.1 N·mm<sup="">–1 – 34.52 ± 2.8 N·mm<sup="">–1, respectively. Eucalyptus clone K7 had lower <i="">MOR and other mechanical properties than clones K58 and K62 except <i="">MOE. When <i="">DBH increased, the mechanical and physical property values increased as well. This happened for all clones, and especially when <i="">DBH was over 200 mm. The results of this study showed that log characteristics, such as taper, slenderness, and crookedness, should be used for log grading standards and that each fast-growing eucalyptus clone could be applied to different product classes.

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