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1

Impact of the Presence of Foreign Bodies on Quality and Value of Oak Timber

Michalec Krzysztof, Wąsik Radosław, Gach Monika

Drewno : prace naukowe, doniesienia, komunikaty

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2023

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Vol. 66, nr 211

Art. no. 1644-3985.438.05

EN

The paper discusses the impact of the presence of foreign bodies on the quality and value of oak timber as raw material. During the study, 109 oak bolts and logs with a total volume of 142.52 m3 were measured and classified. The material for the study came from the Suchowice Forest District, within the Henryków Forestry Inspectorate (in the south-western part of Poland), and it was sampled from a tree stand located on the edge of the forest, where the largest concentration of rifle and artillery fire had occurred during World War II. As a result, the tree trunks contain significant amounts of shrapnel and projectiles. The length and diameter of each bolt and log were measured, and double classification was conducted: the first (I) classification took into account the presence of foreign bodies, whereas in the second (II) classification the presence of foreign bodies was disregarded. As a result of the conducted analyses, it was found that due to the presence of foreign bodies, all of the examined oak raw material was categorised as the worst quality class (D) timber. However, it was noted that during the second classification, where the presence of foreign bodies was not taken into account, a significant part of the raw material was upgraded to better quality classes, and only about 16% of wood remained in the worst, D class. Subsequently, it was calculated that the difference in the total value of the oak timber raw material classified by two methods amounted to approx. 204 thousand PLN (ca. € 43,514) - which was about 35% higher than the value calculated by the first method of classification.

2

The occurrence and size of false heartwood in beech timber

Michalec Krzysztof, Wąsik Radosław, Gach Monika

Drewno : prace naukowe, doniesienia, komunikaty

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2022

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Vol. 65, nr 209

art. no. 1644-3985.385.08

EN

The aim of this study was to analyse the occurrence and size of false heartwood in beech timber over the lower and upper log faces. The research was carried out on 350 beech trunks where the presence of false heartwood was found on at least one of the log faces. The research material came from the Jarosław and Lesko Forest District (the Regional Directorate of the State Forests (RDSF) in Krosno) and the Pińczów Forest District (RDSF Radom). The following measurements were taken on selected logs: the mean bottom diameter, the mean upper diameter, the length of the analysed trunks, the maximum diameter of the false heartwood at both ends. As a result of the research, it was found that the maximum diameter of false heartwood on the beech log faces ranges from 30% to 40%, and a statistical test showed no significant difference in the extent of the defect between the lower and the upper face (t = -0.389; df = 612; p-value = 0.697). An analysis of the presence of the examined feature on the log faces showed that there were cases in which false heartwood appeared only over the lower face or only over the upper one. It was also noted that almost half of the examined logs had a larger diameter of the defect over the upper face than over the lower one. This study also examined the existence of a correlation between the diameter of the log face, log length and the percentage of the defect. The statistical test showed no significant correlation for both the lower and the upper face and the log length.

3

Methods of strength grading of structural timber - comparative analysis of visual and machine grading on the example of Scots pine timber from four natural forest regions of Poland

Wdowiak Agnieszka, Brol Janusz

Structure and Environment

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2019

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Vol. 11, no. 3

210--224

EN

The article covers the strength grading system methodology for construction timber. The presented analysis identified important issues concerning the verification of structural and geometric characteristics during construction timber strength grading by visual and machine method. The following considerations specified the guidelines for the classification of coniferous construction timber in sawmills. The paper also presents the results of the visual and machine classification performed for Scots pine timber from four natural forest regions of Poland. As a result of the conducted research it was stated that the use of machine classification equipment allows obtaining a larger amount of pine timber with better mechanical properties and eliminating the rejected timber.

PL

Artykuł obejmuje metodykę sortowania wytrzymałościowego tarcicy konstrukcyjnej. Przedstawiona analiza określiła ważne zagadnienia dotyczące weryfikacji cech strukturalnych i geometrycznych w trakcie sortowania wytrzymałościowego tarcicy konstrukcyjnej metodą wizualną oraz metodą maszynową. Poniższe rozważania skonkretyzowały wytyczne służące klasyfikacji tarcicy konstrukcyjnej iglastej w tartakach. W pracy ukazano również wyniki badań klasyfikacji wizualnej i maszynowej sosnowej tarcicy konstrukcyjnej pochodzącej z czterech krain przyrodniczo-leśnych Polski. W efekcie przeprowadzonych badań stwierdzono, że wykorzystanie urządzeń do klasyfikacji maszynowej umożliwia uzyskanie większej ilości sztuk tarcicy sosnowej o lepszych właściwościach mechanicznych oraz zniwelowanie liczebności tarcicy odrzuconej.

4

Occurrence of metal elements in cut -to-length pine timber

Płońska-Kaczor K., Szaban J., Kowalkowski W., Kraszewski Z.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2018

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No. 104

80--84

EN

The request of the timber market for good wood quality and requires an examination of metal elements in timber. The quality of contaminated wood is inconsistent with the contract and makes this product less valuable. Both, sellers and buyers want to reduce or to eliminate the problem. The publication compares the percentage content of metal elements in cut-to-length pine timber, which comes from selected Forest Districts belonging to three Regional Directorates of the State Forests. The wood was delivered in two successive years. The aim was also to find the causes of the presence of metal elements in the wood, especially in the Forest Districts, where the percentage was higher than in the other ones.

5

Occurrence of metal elements in cut -to-length pine timber

Płońska-Kaczor K., Szaban J., Kowalkowski W., Karaszewski Z.

Annals of Warsaw University of Life Sciences - SGGW. Forestry and Wood Technology

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2018

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No. 104

234--238

EN

The request of the timber market for good wood quality and requires an examination of metal elements in timber. The quality of contaminated wood is inconsistent with the contract and makes this product less valuable. Both, sellers and buyers want to reduce or to eliminate the problem. The publication compares the percentage content of metal elements in cut-to-length pine timber, which comes from selected Forest Districts belonging to three Regional Directorates of the State Forests. The wood was delivered in two successive years. The aim was also to find the causes of the presence of metal elements in the wood, especially in the Forest Districts, where the percentage was higher than in the other ones.

6

Defects in structural timber

Wdowiak A.

Structure and Environment

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2017

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Vol. 9, no. 2

112--122

EN

The paper presents the defects that are typically found in structural timber. The model of the so-called flawless timber has been made more precise. Additionally, the impact of defects on timber quality was characterised. Defect classification with respect to the time of formation, type and causes was presented. The following defects were discussed in a detailed manner: knots, twisted fibres, cracks, resin pockets, stains, rots, insect channels, wanes, shape defects and sclerenchyma fibres. The main objective of the paper is to show actual imperfections in the conifer wood revealed in the examined elements. The cross-sections of round timber and construction and structural sawn timber were analysed.

PL

W artykule przedstawiono typowe wady drewna konstrukcyjnego. Przybliżone zostały wzorce tzw. drewna bezbłędnego. Scharakteryzowano również wpływ wad na jakość drewna oraz ich podział w odniesieniu do czasu powstania, rodzaju uszkodzeń i ich przyczyn. Szczegółowo zilustrowano sęki, skręt włókien, pęknięcia, pęcherze żywiczne, zabarwienia, zgnilizny, chodniki owadzie, obliny, wady kształtu oraz twardzicę. Głównym celem pracy jest ukazanie rzeczywistych niedoskonałości przebadanych elementów z drewna iglastego. Przeanalizowano przekroje drewna okrągłego oraz tarcicy budowlano-konstrukcyjnej.

7

Strip road impact on selected wood defects of norway spruce (Picea Abies (L.) H. Karst)

Bembenek M., Giefing D. F., Karaszewski Z., Łacka A., Mederski P. S.

Drewno : prace naukowe, doniesienia, komunikaty

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2013

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vol. 56, nr 190

63--76

EN

Creating strip roads in second age class stands is an indispensible operation for carrying out thinning. It is especially important in places where there is an intention to do a first thinning using mechanised thinning operations. Felling trees to create strip roads results in altered conditions for the tree growth of neighbouring trees. In particular, this is due to an increase in exposure to sunlight. This can lead to changes in the growth of trees and consequently changes in the morphology of the trunk and the development of defects. The objective of this paper was to analyse the frequency of the presence of particular defects in the structure and shape of spruce in a five-year period after the creation of a strip road. The research was carried out in an artificially regenerated spruce stand within the spruce’s natural, northern habitat in Poland. A 34-year-old stand underwent a systematic thinning scheme which involved the removal of every eighth tree row. The analysis was carried out on trees growing both adjacent to the strip roads (which had a greater growing area around them and greater access to sunlight) as well as trees from further within the stand. Diameter growth was taken in three places: at breast height, in the middle of the trunk between breast height and the base of the crown, as well as at the base of the crown. The average incremental growth, pith eccentricity taper and ovality were calculated. No statistically significant difference in defects between the trees growing by the strip road and those growing further in the stand was observed. Greater taper on mid-tree logs in comparison to butt logs was observed. Insignificant changes in the morphology of the trunks, supports the validity of cutting strip roads in second age class stands.

PL

Zakładanie szlaków operacyjnych staje się niezbędne przy stosowaniu współczesnych technologii w gospodarce leśnej. Ich obecność to również zwiększony dostęp do światła dla drzew rosnących na ich skraju, co z kolei może wpływać na różnice we wzroście tych drzew w porównaniu z drzewami wewnątrz drzewostanu. Celem pracy była analiza częstości występowania niektórych wad budowy i kształtu mogących wpływać na jakość surowca drzewnego w 5 lat po wykonaniu zabiegu. Drzewostan świerkowy w wieku 34 lat został poddany trzebieży schematycznej poprzez wycięcie co 8. rzędu drzew. Analizie poddano drzewa rosnące przy szlaku PS (z asymetrycznie większymi stoiskami i dostępem do światła) oraz drzewa wewnątrz drzewostanu ( WD 5–10 m od osi szlaku). Badano przyrosty na wysokości pierśnicy, w połowie długości między pierśnicą a podstawą korony i u podstawy korony oraz obliczono przeciętny przyrost, mimośrodowość rdzenia i zbieżystość. Nie zaobserwowano występowania statystycznie istotnych różnic pomiędzy analizowanymi cechami drzew PS i WD, jednakże u drzew rosnących PS zaobserwowano istotnie większą zbieżystość kłód środkowych w porównaniu z odziomkowymi. W krótkim okresie (5 lat) po założeniu szlaków w drzewostanie świerkowym II klasy wieku nie stwierdzono zatem statystycznie istotnych różnic w morfologii pni drzew rosnących przy szlaku i w drzewostanie. Niemniej jednak zaobserwowano: 1) tendencje do zwiększonych przyrostów u drzew PS (szczególnie w połowie pnia) w 5. roku po wykonaniu zabiegu oraz 2) wzrost zbieżystości kłód środkowych wyrobionych z drzew PS. Wyniki te sugerują przeprowadzenie podobnych badań w dłuższym odstępie czasowym (niż 5-letni) od założenia szlaków.

8

Jakość surowca świerkowego pochodzącego z drzewostanów naturalnych (rezerwatowych) i drzewostanów pełniących funkcje gospodarcze

Michalec K., Barszcz A., Wąsik R.

Drewno : prace naukowe, doniesienia, komunikaty

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2013

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vol. 56, nr 189

25--37

PL

W artykule przedstawiono wyniki analizy porównawczej jakości surowca świerkowego pochodzącego z drzewostanów naturalnych (rezerwatowych) i drzewostanów pełniących funkcje gospodarcze. W analizach uwzględniono również wady drewna wpływające na wyniki klasyfikacji badanego surowca oraz częstotliwość ich występowania. Wytypowane do badań drzewostany zlokalizowane były w terenach górskich: w Sudetach i Karpatach. W wyniku przeprowadzonych analiz stwierdzono, że nieznacznie lepsze pod względem jakości surowca drzewnego są w porównaniu z drzewostanami naturalnymi (rezerwatowymi) drzewostany pełniące funkcje gospodarcze.

EN

The aim of this study is to determine the variation in the quality structure of spruce timber and to analyze the frequency of occurrence of trees with defects, including the generic structure of defects in natural stands (forest reserves) and stands serving economic functions. The study was conducted on 20 experimental plots located within the Sudeten and Carpathian Mountains, of which 10 were located in the area of nature reserves or national parks while the other 10 - in the managed stands (table 1). Each experimental plot constituted 5 or 10% of the area of the whole stand, depending on its differentiation. The following tasks were performed on the experimental plots: measurement of the breast-height diameter of each tree with a thickness of at least 7 cm, measurement of the height of each tree, quality assessment of the first section of the tree stem from the base along with its quality-dimensional class or group [Zasady... 2003], recording the types and varieties of wood defects. Analyzing the research material obtained, the stem of each tree growing on an experimental plot underwent simulated division into sections corresponding to the quality-dimensional classes and groups which could theoretically be distinguished over the whole length of a stem up to its top. The starting point was the quality-dimensional class noted in the butt section of the stem (section 1) during the field research. The above tasks included the use of the Radwański tables [Roczniki... 1956], which allowed the determination of the size and volume of each section of the spruce stems on the basis of the breast-height diameter and the tree height; wood defects, noted in field, were also taken into account. The material obtained was divided into 2 groups: data from the reserves and from the managed stands. For the material grouped in this way, juxtapositions were made of the average volumes of individual stem sections in quality-dimensional classes and groups of timber and the percentages of particular timber classes and groups in the two stand types were calculated. The material was also analyzed taking into account the generic structure of defects (percentages of individual trees with particular wood defects in a given group of stands). The next stage consisted in statistical analyses using the U-Mann-Whitney test, examining the significance of differences in the quality-dimensional structure of timber and the share of trees with defects between the two groups of stands. The research showed that trees growing in natural stands (reserves) are characterized by a greater average height, thickness (d1.3 and d1/2) and volume of individual trees as compared with the same characteristics of spruce trees in managed stands (table 2). Also, the average volume of the large-sized timber sections (WA, WB1, WB, WC, WD) of individual trees from natural forests dominated the volume of tree sections in managed stands. Despite that fact, the volume/ha of natural forest stands was lower (355.91 m3/ha) than of managed stands (380.27 m3/ha). By analyzing the quality-dimensional structure of the examined timber it was found that the proportion of higher quality timber classes (WA and WB) prevails in the managed stands, resulting in a lower share of the WC class of timber (fig. 1). Only the share of WB1 class timber prevails in natural stands. The managed stands also showed a larger share of medium-sized timber (groups S1, S2 and S4) as compared to natural forests. The U-Mann-Whitney statistical test, however, did not show statistically significant differences in the timber quality structure between the natural and the managed stands (U = 49.00, Z = -0.0378, p = 0.9698). Subsequently, it was found that the proportion of trees with quality reduced by defects was higher in the natural stands (70.38%) as compared to the managed stands (67.13%). The main defect, decisive for timber quality, were knots (in both groups of stands). The share of trees with that defect was greater in the stands of natural origin (fig. 2). In those stands, there was also a larger share of trees with rot (external and internal rot) and unilateral curvatures. The managed stands demonstrated a share of injuries (overgrown and open ones) as well as bilateral and multilateral curvatures that was higher than in the natural stands. In conclusion, it should be emphasized that in the managed stands within the research area a higher quality of spruce timber as well as higher volume/ha were noted as compared to the natural stands (forest reserves). Stands in forest reserves are generally located at higher altitudes in the mountains or hardly accessible areas; their main purpose are protective functions, they also serve the purposes of research. In the stands situated in forest reserves there was reported, in comparison with the managed stands, a higher incidence of trees with a large number of knots and highly affected by rot. A frequent presence of such defects is inevitable there because this group does not undergo any management cuts that would improve timber quality. Moreover, the presence of rot is due to the advanced age of these stands. At the same time, what is disturbing is a large share of trees with injuries in the managed stands. Given that spruce is very sensitive to mechanical damage of the stem, resulting in rapid development of rot, caution is recommended during forest management work and harvesting in spruce stands.

9

Identifying beech round wood quality - distribution of beech timber qualities and influencing defects

Karaszewski Z., Bembenek M., Mederski P. S., Szczepańska-Alvarez A., Byczkowski R., Kozłowska A., Michnowicz K., Przytuła W., Giefing D. F.

Drewno : prace naukowe, doniesienia, komunikaty

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2013

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vol. 56, nr 189

39--54

EN

The classification of round wood depends on the defects and other morphological features of a tree trunk. Various tree species growing on different forest sites and in different conditions eventually present a wood quality influenced by said factors. The objective of this paper was to find out: 1) the distribution of round wood quality classes of beech in three different site conditions and 2) the frequency of the defects influencing timber grading. The research was carried out on 15 different sample plots of three site quality classes, on which 1389 beech logs were classified according to the existing grading scheme. The most common timber quality (by volume) was WC0 and then in decreasing order: WD, WB0 and WA0, in proportions of: 15:10:4:1. This order was the same for the assortments obtained from the trees in all the analysed site quality classes. The most frequent defects influencing wood quality were knots, among which sound knots were in the majority. The proportion of the appearance of knots was 7:3:2 for sound knots, unsound and dead knots, as well as covered knots, respectively. Sweep, red heart and scars were of a similar frequency to sound knots, approx. 20%. Double pith, shakes, rot, top diameter and spiral grain were of a minor influence on WQCs and together amounted to approx. 10% of the frequency among other defects.

PL

Występowanie wad o zróżnicowanym podłożu szczególnie zależy od warunków wzrostu i rozwoju drzewa. Celem pracy było rozpoznanie udziału klas jakości tartacznego drewna bukowego z trzech klas bonitacji oraz częstotliwości występowania wad. Sklasyfikowano 1389 kłód bukowych (1029,32 m3) na 15 powierzchniach badawczych bazując na obowiązujących regulacjach w Lasach Państwowych. Najczęściej występującą klasą jakości drewna jest WC0, a następnie WD, WB0 i WA0 w proporcjach 15:10:4:1. Bardzo podobny rozkład klas miał miejsce we wszystkich analizowanych klasach bonitacji Sęki, a wśród nich sęki zdrowe były najczęściej występującą wadą drewna powodującą obniżenie klasy jakości. Udział sęków zdrowych do nadpsutych i zepsutych oraz guzów wyniósł 7:3:2. Krzywizna, fałszywa twardziel oraz zabitki wystąpiły na podobnym poziomie częstości, ok. 20%. Wielordzenność, pęknięcia, zgnilizna, zbyt mała średnica w cieńszym końcu oraz skręt włókien mają mniejszy wpływ na klasyfikację tartacznego drewna bukowego stanowiąc razem ok. 10% wszystkich stwierdzonych wad obniżających klasę jakości drewna. Stwierdzono zróżnicowany wpływ klas bonitacji na występowanie krzywizn oraz zabitek. Rozmiar krzywizn w I klasie bonitacji był statystycznie większy, niż w pozostałych klasach. W przypadku zabitek stwierdzono istotnie częstsze występowanie tej wady w III klasie bonitacji.