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EN
Logit and probit models belong to the class of generalised linear models. A few applications of both models have been documented in the field of forestry. The objective of this paper was to test the parallel use of these models to discover the differences in damage to a spruce stand after thinning using the full tree system, the long wood system and the short wood system. In particular the aim was to ascertain the general damage probability caused by the harvesting systems (HS) and the particular damage class probability in each HS. When the general damage probability was calculated the logit model was used. When nine damage classes were taken into account, however, the probit model was found to fit the data better. In this case, the results obtained gave accurate information on the probability of the appearance of a particular damage class for each HS. It was concluded that the probit and logit models should be considered in parallel in order to obtain the best possible goodness of fit and to get accurate information on the distribution of damage classes.
EN
The harvester head causes damage to the bark and wood on the lateral surface of the processed assortment. The severity of the damage may be influenced by the construction of the harvester head and tree species characteristics, such as bark thickness and wood hardness. The study aimed to recognise and compare damage caused to hardwood and softwood. Wood from alder, pine and spruce was harvested using a Valmet 911.4 harvester equipped with a 360.2 head. Logs measuring 2.40 and 2.50 m in length were used in this study. The depth of the damage caused by the feed roller spikes was measured using a digital caliper. Comparison of these defects across the three species revealed that as bark thickness increased so the depth of damage to the timber decreased. Damage to the alder logs in the form of dents and gouged timber fibres was shallow: from 1.7 to 3.7 mm, and significantly less than that to the softwood logs: in the pine from 5.9 to 7.8 mm, and in the spruce from 3.9 to 5.6 mm. Damage to the middle and top logs for each species was similar and depth varied little along the entire length of the processed assortment. Such damage only slightly lowered the quality of the alder wood, which had the thickest bark. Application of the Valmet 911.4 harvester caused less damage to the alder wood than to the softwood (pine and spruce).
EN
Seedling seed orchard (SSO) growing conditions are different to those in the forest. Trees grow in wide spacing with more access to sunlight and competition between trees is less intense causing larger annual rings and limited height growth. The objective of this research was to: 1) determine the density and mechanical properties of Scots pine (Pinus sylvestris L.) wood grown in an SSO and 2) suggest the most suitable use of this wood. Five trees (25-year-old) were selected using the Urich II method. Final samples (from the height of dbh) were cut from pith to bark, in the four cardinal directions. From all five trees, 159 samples were used to determine: 1) the wood density, 2) the compressive strength parallel to the grain, 3) the modulus of rupture, and 4) the strength quality coefficient. For each property the following mean values were obtained: 327 kg m-3, 32 MPa, 59 MPa and 0.10, respectively. The density did not depend on the dbh or mean width of annual ring. At the same time, the mechanical properties depended strongly on the wood density. In all cases, the wood property values of the Scots pine from the SSO were lower in comparison with those published for Scots pine grown in regular stand conditions. Therefore, pine wood from SSOs should be used in the paper industry.
EN
Differences in the intensity of silvicultural treatments, as well as natural tree mort- ality, insect damage and fungal disease can eventually lead to variable stand density even on sites of the same quality. In addition, the bigger the initial stand density, the smaller the crown and trunk volume of single trees. The objective of the research was a detailed analysis of the impact of stand density on the total stand volume and value of merchantable timber. The area studied was in Drawno Forest District, north-west Poland, on sites with sandy soil conditions typical for Scots pine (Pinus sylvestris L.). The total volume of merchantable roundwood was measured on 20 sample plots (each covering an area of 0.5 ha) of which 19 were in 82-year-old stands and one in an 87-year-old stand. The stands were divided into three stand density groups (SDG), where the average number of trees growing per group was as follows: 547 (SDG I), 651 (SDG II) and 765 (SDG III). The volume of a single tree was calculated using diameter (DBH) and height measurement. A quality classification of all 6432 tree stems was carried out in accordance with the Polish Standard. Statistical analysis did not indicate that density influenced the total timber volume of the stands studied, which was recorded as an average of 323 m3∙ha-1. However, statistically significant differences in the value of merchantable timber were observed: the highest value of 100 m3 of merchantable timber was recorded in SDG I (€ 5118.87), 6 and 12% higher than in SDGs II and III (€ 4842.09 and € 4565.80, respectively). The results obtained suggest that in the final phase (the last two age classes), pine stands growing in Polish conditions should be maintained at a lower stand density.
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.
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.
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