The study presents the health condition and structure of pine stands growing on permanent experimental plots in the Kwidzyn Forest Division, the Ryjewo working circle, the Lisewo Forest District. Forest mensuration analyses were performed in a 127-year old pine stand (compartment 214), in five plots of 0.26 ha each. The health condition of the stand was determined on the basis of the losses of the assimilatory organs, i.e. defoliation. Mean defoliation of tree crowns was 20.3% (below the warning level), which corresponds to the damage rate of 1.14. A vast majority, i.e. 67% of the 176 analysed trees, represented damage rate 1 (Table 2). Taking into consideration the age of the stand (127 years) and its provenance (it was planted on former farmland) the health condition may be considered good. The structure of social classes of tree position in the stand shows an appropriate share of the upper storey (81.2-95.1%) and the second storey (4.9-18.8%). When analysing the basic characteristics of the stand structure it was found that the biggest variation was observed in crown length (from 17% to 30%), while the smallest – in height (from 6% to 9%). The mean relative crown length in the stands ranged from 0.21 to 0.24. Tree slenderness, defining resistance of trees to damage caused by wind and snow took mean values below 1.0 (from 0.71 to 0.83). This shows good stability of the analysed stands. Those stands are characterized by high yields of 465-614 m³ large timber per 1 ha and stocking of 1.0 to 1.3. As a result of the analyses of the interdependencies between the basic mensuration characteristics the most significant relationship was found for diameter at breast height and slenderness (from –0.718 to –0.913), height and absolute crown length (0.619-0.715) and diameter at breast height and height (0.161-0.708; Table 4). The trends in the annual increment in diameter at breast height showed the biggest decreases in the years 1977-1983, 1969-1974, 1962-1967, 1956-1960 and 1949-1952 (Fig. 6). Those periods coincide with gradations of nun moths and adverse weather conditions.

The aim of the work was to determine which part of biomass remains in the forest in the form of so-called logging residue. In order to achieve the result, the analysis of wood volume harvested in the final felling was carried out, and the total volume was broken down into different parts of trees. Furthermore, to estimate the wood volume of the forest stand, on each of the experimental plots 10 model trees were chosen based on Draudt method. Assuming that the thickness of wood acquired from forest is bigger than 4 cm, it is possible to assume that the part of biomass which remains in the forest in the form of the branches and conifer needles ranges from 10% to 12% of general amount of biomass.

Forests play a very important role in the process of the carbon cycle in the natural environment and timber harvesting disturbs the natural circulation of this element considerably. Moreover, the way of handling the post clear cutting residues can also influence the accumulation of carbon in the soil. Usually, increased contents of organic carbon in the near-surface layers of mineral forest soils were observed in the first year following the stand removal. The greatest soil carbon enrichment was recorded when branches were ground and mixed with the mineral soil. Considerable variations in the observed contents of organic carbon in the near-surface layer of mineral soils during the first two years after clear cutting and later makes it impossible to indicate the most advantageous method of management of post clear cutting residues.

Tree ring chronologies of Scots pine (Pinus sylvestris L.) and black pine (P. nigra Arnold) from the dry coniferous forest and the fresh mixed coniferous forest, as well as black alder (Alnus glutinosa (L.) Gaertn.) from the alder swamp forest, in the Słowiński National Park and neighbouring forests (Damnica Forest District) are presented. For both pine species 1940, 1956, 1976, and 1996 were the negative signature years, while 1946, 1957, and 1989 were the positive ones. In black alder the diameter increment depressions occurred in 1997 and 1998. The tree ring width in both pine species was positively correlated with the mean monthly air temperatures in February and March, while there was no univocal precipitation-tree growth relationship found. In some cases, in black pine from the fresh mixed coniferous forest and black alder from the alder swamp forest, the statistically significant coefficients describing the precipitation-increment relationship had negative values. The increment depressions, which occurred in both pine species during 1981- -1983, were the result of the nun moth (Lymantria monacha L.) outbreak. Black alder was not attacked by this phyllophagous insect. The positive July precipitation-tree growth relationship was found in both pine species during the nun moth outbreak.

The primary objective of the research project was to determine the variability of the taxation characters of pine stands during individual cycles of forest management work in the period extending from 1963 to 2004. The authors assessed changes in the forest species composition which took place in the Zielonka Experimental Forest District, especially, the proportion of Scots pine. It is evident from the performed analyses that the share of pine in the discussed object decreased during the examined period of time by nearly 7% and, in 2004, it reached the level of 82.7%. The oak increased its share from 5.1% of the forest area in 1963 to 12.3% in 2004. The obtained results corroborate a systematic increase of the stand current increment and volume. Changes in the proportion of forest sites (19% in 1963 and 78% in 2004) indicate that there is a need for the modification in the ways of forest management, especially in the case of pine stands which are artificial and unsuitable for the site.

It was attempted to study the effect of stand density on the stem form of Scots pine trees. To estimate stand density the index SDI of Reineke (1933) was used. The analyses carried out showed that the stand density index has no significant effect on values of breast height and specific form factors. The detailed analysis of the stem form curve permitted to conclude that stand density affects the form of the top part of the stem profile. Trees in stands of low density in comparison with trees in stands of high density are characterized by lower values of relative diameters in the top part of the stem, especially in the range from 0.7 to 0.9 of the tree height. However, differences in stem profiles of trees from stands of different density are significant only in the range from 0.82 to 0.89 of the relative height. Using the stand density index in the empirical equation for determination of volume does not increase its accuracy.

This paper presents the results of investigation into the variability of the share of heartwood on the stem cross-section of Douglas fir in Poland. The research was conducted in Douglas fir stands in the IV and V age classes. The feature was analysed on increment cores taken from the trees at 1.3 m level from the base of the stem, in the N and S direction. The differences of the share of heartwood between Douglas firs of the V and VI age classes as well as between the trees growing in moderate and broken crown closure were not significant. No significant differences occurred between specimens of different vitality, either; however, the trend towards increasing the share of heartwood in weak trees with relation to normal and lush ones was noticeable. No significant correlations between the share of heartwood and crown parameters were noted. Three regions were distinguished in the territory of Poland: the southern and north-western ones, where Douglas firs have a higher share of heartwood on the stem cross-section, and the central-western one, where the share is lower.

The study assessed pruning efficiency of Scots pine (Pinus sylvestris L.) using different types of specialist pruning saws. Elements used in the study included the diameter and number of removed knots, pruning time per tree and passage time from one tree to another.

The article presents results of the research on the shrinkage of slightly degraded, freeze-dried archaeological oak-wood (Quercus sp.). Before drying, samples of wood were treated with 10, 20, and 30% water solutions of PEG 300, PEG 4000, and sucrose, as well as the mixture of both polyglycols. Dimensional changes in tangential, radial, and longitudinal directions were determined immediately after freeze-drying, and then, after seasoning of the freeze-dried samples in the air at RH 44 and 70%. Shrinkage of untreated and treated freeze-dried oak-wood was considerably smaller, than that of the material, which was dried naturally (ASE_T from 49 to 97%, ASE_R from 39 to 98%).

The study investigated properties of particleboards resinated with PMDI modified with polyethylene glycols with varying molar masses (PEG 200 and 400). The conducted investigations showed that PMDI resin modification with both PEG 200 and PEG 400 causes an increase in mechanical properties of manufactured boards. In turn, modulus of elasticity decreases with an increase in plasticity of the modified resin. Then, water resistance of the tested boards, measured by their tear resistance after the boiling test, irrespective of the type and the amounts of applied modifiers, is very high and considerably exceeds the requirements specified in the respective standard. Particleboards exhibiting better mechanical properties and considerably improved water resistance may be obtained by the modification of PMDI resin with polyethylene glycol of a higher molar mass.

The study investigated execution tolerances and profile load capacity curves occurring in industrial conditions. Using graphic images of fits expanded by profile load capacity curves, an attempt was made to explain the effect of the profile load capacity curve on the fitting character of the tenon joint.