Tomasz Jelonek

• Professor
• Professor (Assistant) at University of Life Sciences in Poznań

This study investigates the effects of aging trees on wood properties, which are caused by climate change, the withdrawal of coniferous species from Central Europe, and the increased crown sweep in old beech stands. The research was carried out in old tree stands with a high proportion of Scots pine (Pinus sylvestris L.) and beech (Fagus sylvatica...

Petrol brush cutters are among the most widely used devices for tending young forests. During this work, environmental pollution is generated by the combustion of fuel and by the discarding of pieces of the plastic cutting line. The aim of this study was to compare operating parameters and the degree of plastic pollution from the cutting line, and...

Climate change and the gradual phaseout of the spruce from Central Europe inspired us to study the effects of the ageing process of trees on wood properties. This study was conducted in old tree stands with significant involvement of the spruce (Picea abies (L.) H. Karst) in the ages between 122 and 177 years. The study material (samples) was colle...

Currently, a wide spectrum of solutions can be found on the technology market which uses photo-optical measurement methods for estimating the gross volume of roundwood stacks based on pixel recognition, stereoscopy, and LiDAR sensors. Therefore, the digital systems for roundwood measurements can be classified into two groups: 1) applications that r...

The paper is a study of risk assessment posed by trees in selected urban woodlands (urban forests) of Warsaw. Two groups of trees were analysed and compared: exhibiting signs of maturity and ageing (hollow-bearing trees with open or hidden cavities and/or caries) and with no signs of decay. 373 individual trees growing near routes frequently or con...

Wood quality is a characteristic which refers to specific, sustainable purposes for the use of wood raw material. Various wood properties are used to determine the wood quality: anatomical, physical, and chemical, which influence the final wood product. This assessment can be estimated on standing trees before harvesting or on logs after harvesting...

Frost ribs (frost cracks) are common wood defects in oak stands. Tree trunks with frost ribs cannot be used as high−quality industrial wood. Considering the great economic importance of oak for forest management, the objectives of this study were to determine the proportion of trees with frost ribs in the stand, to characterize frost ribs, to compa...

This study was conducted in Central Europe (Poland) in pine forests that were subjected to the process of resin harvesting in the 1970s. Forty trees were designated for the study, which had one or two resin blazes. The objectives of the experiment were to determine the effect of resin tapping on the changes in annual growth, wood density, and mecha...

By damaging bark, mechanized harvesting deprives wood of its natural mechanical barrier. This study concerns the effect of this damage on the changes in moisture content that occur near the damaged areas of Scots pine (Pinus sylvestris L.). This study was carried out using 45 randomly selected 11 m long logged pine stems. Additionally, the effect o...

This research was conducted in the forests of Poland between 2019 and 2022. The aim was to study Scots pine provenances and compare the wood density variability among the various provenances growing on one experimental plot (in situ). The experiment was established in 1962 in the Zielonka Forest Division, Potasze Forest District. In 2019, five mode...

This experiment was conducted in the pine woods of central Europe at a research area established in 1951. The experimental area of 1.35 ha was set up in a 14-year-old pine tree stand, which was divided into lots, and the pruning procedure took place in different variants. Some lots constituted control lots without pruned trees. The trees were prune...

The aim of the study was to analyse the changes in the infection rate development inside the beech stem as a result of browsing by deer (Cervus elaphus). The research materials were collected from three research plots located in the Polanów Forest Inspectorate from March to April 2020. For the study, 80 beech trees were selected, for which the size...

Harvesting large quantities of timber requires the use of various technical means, including harvesters. The introduction of machine logging has greatly improved safety and reduced accident rates but has also resulted in the risk of musculoskeletal disorders and increased psychological strain. The aim of this study was to determine the level of the...

Objectives: This study examined the physiological strain experienced by workers employed in motor-manual timber harvesting performed in winter and summer, and the applicability of heart rate indices for estimating energy expenditure. Material and methods: The heart rates (HR) of 2 teams consisting of 2 persons working simultaneously during felli...

To determine the appropriate final use of wood from a particular tree species, it is first necessary to know its properties. Methods that use wood samples taken directly from the trunk of a growing or felled tree are very time-consuming and require a great deal of manual work. Non-destructive methods may be more effective and much faster, thanks to...

This study evaluated within-stem differences in the moisture content of stored summer-harvested oak wood with respect to drying method. The felled oaks were naturally dried for eight weeks, from 4 July to 29 August 2017. We analyzed two methods of preparation and storage: a transpiration drying method (W), and an air-drying method for stem-wood (L)...

The research focused in determining the lignification indicator of fresh needled springs and the mass of fresh needles in reference to the lignin content in tracheid walls of peripheral area of the stem (MFT/LC and MFN/LC) of Scots pine differentiated as far as its biosocial position within the community expressed by Kraft’s classification. The mat...

Silver birch (Betula pendula Roth) is classified in diffuse-porous wood category. In this case structure of wood tissue is quite similar across whole cross-sectional area. The aim of this study was to analyse cross-section variability of moisture content (MC) of growing silver birch wood, significant hardwood species in Polish forests. Investigatio...

Heavy metal pollution causes many soils to become a toxic environment not only for plants, but also microorganisms; however, little is known how heavy metal contaminated environment affects metabolism of phytopathogens and their capability of infecting host plants. In this study the oomycete Phytophthora infestans (Mont.) de Bary, the most harmful...

Survival in variable conditions of wind exposure depends on the strategy of trees in adapting to environmental constraints. There are many studies investigating the effect of wind on the adaptation of trees, but little attention is paid to the properties of the wood, particularly within-stem variability. In the present work, an analysis was made of...

The purpose of this study was to establish the impact of season on productivity, labour consumption, and working time structure during timber harvesting from young alder stands (Alnus glutinosa Gaertn.). An early thinning process was performed in summer and winter in pure alder stands (38 and 40 years old) in the Płaska Forest Division (NE Poland)....

Wood properties have an influence on the safety around the tree itself as well as on actual possibilities of using wood. The article focuses on the wood properties of the Norway spruce (Picea abies (L.) Karst.) in reference to the time since the tree has decayed. The study was conducted among mature tree stands of spruce in Białowieża Forest, where...

Plants produce a large variety of natural products. Terpenes seem to be the largest and the most important group of secondary metabolites in conifer trees. They protect the plant from invading pathogens and herbivores by representing constitutive or induced defense mechanisms. Moreover, antioxidant properties of some terpenes have also been shown,...

This work presents the results of selected wood properties in birch trees grown on a provenance experiment plot established as a seed orchard. The study concerned: basic density, oven-dry density and compression strength along the grain at a moisture content of 0% and at moisture content above fiber saturation point. Analyses were performed on 971...

This study evaluated changes in mass and the moisture content of stored summer-harvested Scots pine small diameter roundwood subject to different types of preparation and storage (drying methods). Small diameter roundwood was naturally dried for three months, from 15 June to 15 September 2018. We analyzed three methods of preparation and storage. F...

The aim of this paper is to analyze the changes in accident rates resulting from the privatization of forest operations. Data from the years 1990–2017 were obtained from the Statistical Forestry Yearbooks issued by Statistics Poland, and were analyzed for two periods: the time of intensive privatization (1991–2002) and the post-privatization period...

Tree biomechanics and biomechanical tree stability are research problems that have been discussed in world literature for many years. The biomechanical profile formation in trees is an extremely complicated problem and has not been fully clarified to date. It is influenced by many factors, which determine tree growth, tree development, multifunctio...

The aim of this study was to investigate the effect of season of the year on the frequency and degree of damage to residual trees caused during winter and summer timber harvesting operations in young alder stands. Analyses were conducted in pure black alder (Alnus glutinosa Gaertn.) stands aged 38 and 40 years, located in north-eastern Poland. Chai...

The study demonstrates protein tyrosine nitration as a functional post-translational modification (PTM) in biology and pathobiology of the oomycete Phytophthora infestans (Mont.) de Bary, the most harmful pathogen of potato (Solanum tuberosum L.). Using two P. infestans isolates differing in their virulence toward potato cv. Sarpo Mira we found tha...

The aim of the study was to recognize the annual worktime structure and the actual number of working hours at the forester and deputy forester workstations in the State Forests. The research was carried out on the sample group of 462 workers in all regional directorates of the State Forests in 62 forest districts and 242 forest ranges. The study gr...

This paper compares the characteristics and properties of wood from trees grown on forest land with trees grown on former farmland. The first generation of the tree stand, which was artificially introduced on lands previously used for farming, was accepted as an ecosystem on the former farmland. A total of 36 trees from twelve areas were chosen for...

W pracy przedstawiono przegląd literatury dotyczącej przemysłowego wykorzystania rodzaju paulownia. Celem pracy było zweryfikowanie aktualnego stanu wiedzy na temat wykorzystania drewna paulowni oraz możliwości uprawy przemysłowych odmian paulowni. W pracy opisano botaniczną przynależność, krótki rys historyczny, wymagania klimatyczne, zastosowanie...

In the xylem of growing trees water fills both free spaces in the cell walls and capillary spaces. For this reason its share in the tree mass is very high. As a result transport of logs obtained from fresh-felled trees is mainly equivalent to the transport of contained water. The primary aim of this study was to determine wood moisture content in g...

The aim of this study was to measure the weight of timber obtained from freshly cut trees and compare it with the applicable legal provisions pertaining the capability of transporting heavy loads by hand and also to indicate a problem significant for the occupational safety and health protection of employees working at wood harvesting. In Poland, a...

Timber harvested from fresh-felled trees has high moisture content and relatively high mass. During storage, the timber dries out and its weight decreases with the loss of moisture. The main objective of this study was to determine how the method and conditions of short-storage in summer affect weight changes and moisture loss in beech timber (not...

Wood obtained from freshly cut trees has a high moisture content and therefore its mass per volume unit is higher than the mass of dry wood. The natural drying is a simple and effective method of weight (moisture content) reduction, making a better use of the vehicle's payload, and thus reducing costs, including environmental costs. The conclusion...

Introduction and Objectives Holding determined body postures during work is connected with muscles activity. The more forced the posture, the larger the number of muscles taking an active part in holding and stabilizing the work posture. During logging, the greatest share of awkward (forced) working postures occurs in tree felling by chainsaw. Mat...

Background. The presented study is focused on the analysis of the relationship between slenderness and selected biometric characteristics of Norway spruce (Pieca abies (L.) H. Karst) stand growing at the mixed fresh coniferous forest site. Material and methods. Data was collected on three plots established on the permanent experimental plot of the...

This study attempted to define the shaping of the quotient of fresh-needled twig mass and fresh conifer needle mass to the lignin content (MFT/LC) in the tracheid walls of the circumferential zone of trunks (MFN/LC) of pines with various forms of dead bark, which were called lignification markers. In the experiment, the researched trees had varying...

This paper is an attempt to evaluate the lignin formation in tracheid walls within the stem circumferential area in mature Scots pine (Pinus sylvestris L.), and establish the correlation between lignin content, and diameter at breast height and hydraulic conductivity in mature pine. The independent variables included lignin content (L c) in trachei...

This paper is an attempt to evaluate the lignin formation in tracheid walls within the stem circumferential area in mature Scots pine (Pinus sylvestris L.), and establish the correlation between lignin content, and diameter at breast height and hydraulic conductivity in mature pine. The independent variables included lignin content (L c) in trachei...

The aim of this work was analyse the variability in static modulus of rupture (MOR) and modulus of elasticity on static bending (MOE), in the trunks of pines. We put forward the hypothesis that the analysed properties will take higher values in the case of slender trunks, and additionally that the variation in the properties in slender trunks will...

The aim of this study was analyse the variability in basic density (Qbd) and compression strength parallel to grain of the wood in pine trunks (Rc). We put forward the hypothesis that the density and strength of the wood will be greater in more slender trunks, and that the variability in the properties in slender trunks will be smaller. The study w...

The study objectives included: i) determination of the mass and green density of pulpwood (wood+bark) and ii) comparison of the changes in these parameters during 14−day−long storage period. The experiment was conducted between 15 and 28 July 2014 and the material was taken from the 67 year−old Scots pine stand (Tuchola Forest District, northern Po...

The effect of short-term (48 h) moderate (85 μM CdCl2) and high (170 μM CdCl2) cadmium (Cd) stress on endogenous peroxynitrite (ONOO−) generation was investigated in the roots of 2-days old seedlings of soybean (Glycine max L.). The control roots showed a relatively high level of ONOO−, whereas Cd-mediated ONOO− formation was detected only at high...

The aim of this analysis was to determine the mass of pine pulpwood, harvested from fresh-cutting trees. Analyses were made in four pine stands (aged 45, 47, 55 and 56). In each plot a total of 30 model trees were selected from among trees to be felled as a part of planned intermediate cutting. The average mass of one log of 2.5 m length ranged fro...

An analysis of the quality and value of timber in pine tree stands representing selected ecotypes of this species in Poland This paper attempts to compare the value and quality of the Scots pine (Pinus sylvestris L.) represented by four of its ecotypes, i.e. Bolewice, Gubińska, Taborska and Supraska. The research was carried out on old pine tree st...

The form of dead bark in Scots pine (Pinus sylvestris L.) and selected biometric features and indicators. The paper attempts to define a relation between the values of some selected biometric features and indicators and the forms of dead bark in trees. Material for the study came from pure pine stands aged from 89 to 91 years, located in the Northe...

Changeability of tree tissue properties of the Scots pine (Pinus sylvestris L.) as a marker of trees' ageing This paper attempts to delineate the effects of the ageing process of trees on the quality of the tree's tissue circumscribed by its properties, i.e. basic density (Qu) as well as the static bending strength of absolutely dry wood and of max...

Carbon content in Scots pine wood depends on growth and development conditions and also varies across different sections of the trunk. Identifying this variability enables to establish the phases of tree growth, in which carbon accumulation is the most intensive. The aim of this study was to determine the carbon content of juvenile and mature wood...

The study compared the dimensions and indicators of the crown of trees that differ in slenderness. Two series of model trees were analysed, with respectively smaller and greater breast-height diameter. It was assumed that irrespective of the thickness of the trunk, as the height and slenderness varied, the crown architecture would vary proportional...

The effect of tree senescence on wood tissue characteristics in Scots pine (Pinus sylvestris L.). It was investigated how the process of tree ageing affects characteristics of the wood tissue, defined on the basis of variation in the width of annual growth rings. Three stands were chosen for the study, aged between 155 and 166 years, from which a t...

In this study we proposed peroxynitrite (ONOO¯) as an important player of defence responses during the interaction of potato (Solanum tuberosum L.) and the oomycete pathogen Phytophthora infestans. As we found, the potato-avr P. infestans model system exhibited a transient program of boosted ONOO¯ formation correlated in time with the burst of nitr...

The relationship between such tree characteristics as tree height and diameter at breast height and the resulting wood properties has not been investigated in depth to date. The phenotypic variability of Scots pine is associated with high variability of xylem even within one population of this species. Thus it seems advisable to focus in research o...

The effect of tree senescence on selected properties of wood tissue in Scots pine (Pinus sylvestris L.). It was investigated how the process of tree ageing affects the quality of the wood tissue, defined in terms of two properties: the basic density (Qu)and the modulus of elasticity in static bending (MOE). Three stands were chosen for the study, a...

Morphological architecture of different ecotypes of Scots pine (Pinus sylvestris L.) in Poland. In this paper, we attempted to accurately describe and compare the morphological architecture of Scots pine (Pinus sylvestris L.), representing three different ecotypes from Bolewice, Gubin, and Tabórz. The samples come from old pine stands aged from 104...

Weight and green density of oak pulpwood harvested from the selected stands of Łąck Forest Inspectorate. The paper presents the results of a pilot study the aim of which was to define the actual weight of oak pulpwood. The average weight of a single log with bark is 23,3 kg (0,025 m 3). By dividing the total weight of the green wood material in bar...

Weight and green density of birch pulpwoodharvested from the selected stands of Kaczory Forest Inspectorate. The paper presents the results of a pilot study which was organized in the Kaczory Forest Inspectorate area. The aim of the study was to define the actual weight and green density of birch pulpwood. According to the applied methodology, the...

The relationship between such tree characteristics as tree height and diameter at breast height and the resulting wood properties has not been investigated in depth to date. The phenotypic variability of Scots pine is associated with high variability of xylem even within one population of this species. Thus it seems advisable to focus in research o...

Density is one of the most important properties, on the basis of which other characteristics and attributes of lumber are evaluated. One of its more practical applications is in the evaluation of the load mass of pulpwood. Taking into consideration the high variability of lumber density and how this attribute is influenced by the habitat, a pilot e...

Research was carried out in Scots pine (Pinus sylvestris L.) stands damaged by strong wind in six locations in Poland. The aim of this study was to analyse the radial variation of compressive strength parallel to grain in the wind−broken trees and neighbouring survivors. Strength tests were conducted in moisture above saturation fibre point. There...

The paper presents variability in morphological traits of trees in mature Scots pine stands exposed to wind. The analysed parameters included breast height diameter, tree height and length, diameter, lateral area and crown base area. Except for the crown base area and crown diameter, values of the other traits increased with an increase in the dist...

It was assumed in this study that growth and development conditions for trees growing on former farmland in relation to those found in typical forest sites may have a significant effect on the formation of tree tissue and thus influence the biomechanical stability of trees. In this study the term tree biomechanics refers to radial and axial variabi...

The soil of former farmland greatly differs from forest soil, and significantly influences tree growth and development compared with other site factors. The effect may also be reflected indirectly in radial variability of wood. This study compared radial variation of wood density, compressive strength along the grain and static bending strength of...

The aim of the study was to determine the effect of selected tree stability indices described by individual biometric characteristics on the formation of their wind resistance. The analysis of tree stability was based on easily measurable tree traits, such as height, breast height diameter, crown parameters as well as the centre of gravity and slen...

We assumed that wood of trees undamaged by wind will be characterized by higher basic density than wood of damaged specimens. It was stated that wood of windthrow had lower basic density, but differences were not statistically significant. Two parts of wood: compressed and tensioned zones) were analyzed separately. Higher density was found in tensi...

The study consisted of the analysis of the morphological structure and properties of wood tissue in trees growing in nine stands exposed to the action of wind. Each stand was divided into three zones of wind loading exerted on the trees. The results indicated that the first wind load zone (A) in the case of each examined tree differs from the other...

The study comprised an analysis of axial variation in modulus of elasticity (MOE) in wood of Scots pine growing in mature stands particularly exposed to wind. Investigations were conducted on 72 trees growing in eight different localities in northern Poland (the Regional Directorate of the State Forests in Szczecinek). Axial variation in modulus of...

The paper presents a review of studies on the structure and properties of wood in relation to loads and damage of trees caused by wind. These two are the characteristics commonly used in the analyses of relationships between the tree and conditions of its growth and development.

Technical parameters of wood vary markedly in the tree stem. In case of coniferous trees annual increments in diameter located in the central part of the stem cross−section exhibit completely different properties than increments formed by trees at an older age. Due to this heterogeneity the central part of the stem cross−section is denoted by the n...

The sequence of events leading to the programmed cell death (PCD) induced by heavy metals in plants is still the object of extensive investigation. In this study we showed that roots of 3-day old yellow lupine (Lupinus luteus L.) seedlings exposed to cadmium (Cd, 89μM CdCl(2)) resulted in PCD starting from 24h of stress duration, which was evidence...

Abstract. The relationship between the biometric traits of Scots pine (Pinus sylvestris L.) trees and their total needle biomass was analysed and the foliage of these trees growing in 38 stands in northern and western Poland was modelled. Productive pine stands were chosen on former farmland and forest soil providing locally optimal conditions for...

Trees in a stand have different positions and those in the outer stand ring are most exposed to the wind. Around the crowns of border trees the wind causes turbulence which affects trees in the centre of the stand. All the trees in the stand resist the wind, which loses its strength; the deeper in the forest, the weaker the force of the wind. Those...

It was attempted in this study to determine the effect of former farmland soils on biomechanics and stability of trees by analyzing axial variation in basic density of wood, bending strength of absolutely dry wood and that of wood with moisture content over fiber saturation point. The analyses were conducted on wood of Scots pines grown on four pos...

Compression strength along the grain in twin samples (wet and absolutely dry) coming from wood of wind-broken trees of Scots pine (Pinus sylvestris L.). Analyses were conducted on two experimental stands damaged by strong wind I north part of Poland. This paper is a part of a cycle of research conducted in pine stands, which suffered from windfall...

The paper analyzes pure density of wood in wind-broken trees and standing trees (control) coming from two stands damaged by strong wind (the Świdwin and Kolbudy forest districts). Generally a higher wood density was found for the control trees. The difference was 2 kg/m3 and it was not significant statistically. A similar result was recorded for th...

The study analysed values of modulus of elasticity at static bending in the tangential direction for wood of wind-broken trees and standing trees (control) coming from two stands damaged by strong wind (the Świdwin and Kolbudy Forest Divisions). Analyses were conducted at moisture content above fiber saturation point (wet samples) and at zero moist...

Modulus of Rupture in twin samples (wet and absolutely dry) coming from wood of wind-broken trees of Scots pine (Pinus sylvestris L.). Analyses were conducted on two experimental stands damaged by strong wind I north part of Poland. The aim of this study was to determine whether static bending strength of broken and undamaged trees differ from one...