Research concerned features of trees and timber of Norway spruce, a species with high genetic and environmental variability. Sample plots were set up in 28 stands in the mountains of the Beskid Żywiecki (region in southern Poland). Stands were grouped according to the lower and upper forest zone and trees according to branch type, i.e. comb-like, brush-like, flat and mixed. The results of the χ² test confirmed a significant relation between, on the one hand, a relative height of the crown base, the structure of timber quality and size and a tendency towards a change of technical quality of timber – and, on the other hand, altitude and branch type. The width of annual rings in the analysed material was related only to altitude. It did not depend on the branch type. The presence and percentage of rot did not depend on altitude. The percentage of rot was connected only with type of branches.

Since the seedling phase is the most vulnerable stage in the life cycle of a tree, their hydraulic system needs to be protected against the harsh climate found, for example, on boreal clearcuts. There are commonly-used methods of hardening plants. But these are difficult to apply, limited in their effectiveness, and tend to slow the growth of plants. To identify simple, yet effective, methods of protecting plants, their own natural, phenylpropanoid defences were activated. This could be done using either antioxidants or ultra-violet light (UVB) to provide a kind of ‘immunization’ against the damaging effects of stress. Low to ambient levels of UVB were found to increase phenylalanine ammonia lyase (PAL) production, and the resulting increase in flavonoid synthesis enhanced hardiness and seedling vigour. To study how seedlings acclimate to chronic stress, a computerized root misting system was used to supply a series (mild to severe) of root dehydrations. Drought acclimation varied with the species, ecological niche and number of stress cycles, when species from drier (jack pine) and moister (black spruce) regions of the boreal forest were compared. Black spruce showed earlier stomatal closure and the more rapid decline in hydraulic conductance (K) indicated the earlier onset of cavitation in black spruce. Static features in jack pine postponed dehydration (e.g., a larger root area and smaller needle area). Although jack pine was unable to adjust turgor, or K, it was more resistant to cavitation. While a high K is necessary for rapid growth, cavitation can limit K, which could aid survival when drought becomes severe.

The paper presents results of observations of Scots pine tree crowns carried out in 2002 in the Sokolniki working circle of the Przedborów Forest Division. The evaluation comprised the total of 500 trees growing in pine stands of the IIIrd and IVth age class selected on the basis of investigations conducted on experimental surfaces with 25 trees from the main stand. It was found that the condition of crowns was either unsatisfactory or warning and this could be attributed to the local emitter of contaminations, i.e. the “PROSPAN” Chipboard Plant in Wieruszów.

Three among 18 tested infusions of flowers acted in a deterring way on large pine weevil cockchafers. Repelling effect was shown by infusions made of flowers of the following plants: Centaurea cyanus L., Sambucus nigra L. and Galeobdolon luteum Huds. No attracting action was found among the studied species. The aroma of preparations made of the remaining plant species had no statistically significant effect on the behaviour of large pine weevils.

The work is an attempt to define the food demand in the particular larval stages of pine moth Dendrolimus pini L. It has been demonstrated that the amount of autumnal food consumed is about 7-11 times smaller than the spring one. The amount of food consumed in autumn by one caterpillar is on the average 2-3 g, while the spring food consumption ranges between 14 up to as many as 34 g. This work is a continuation of studies aiming at the determination of the amount of food demanded in the particular larval stages by the more important phyllophages.

It was found that the biomass of 75-year-old pine stands was 184.0 t·ha^-1, ranging from 168.5 t·ha^-1 to 203.0 t·ha^-1. Generally, the total stand biomass increased with improvement of site conditions. The tree layer was its major component making 155.5 t·ha^-1 on the average, i.e. 84.5%. The mean biomass of the bark was 21.5 t·ha^-1 (11.7%) and the needles 5.6 t·ha^-1 (3.0%), while that of the undergrowth and shrub layer 1.4 t·ha^-1 (0.8%). The wood of the tree layer generally did not make more than 66% of the biomass production understood as the amount of dry matter produced in a year. It ranged from 3.591 t·ha^-1 to 4.259 t·ha^-1. The biomass of the annual foliage, ranging from 2.020 t·ha^-1 to 2.344 t·ha^-1 made from 32.1% to 39.3% of the biomass increment, while the increment of the undergrowth and shrubs did not have any significant effect on annual production of pine stands.

In the Świętokrzyski National Park, fir trees (41 to 300 years of age at breast height) were characterised by a regular radial increment until about 1960, then there was a very strong increment decline between 1960 and 1985, and regeneration after 1986. Beech trees (21 to 200 years of age at breast height), in the same period of analysis (1880–1994) showed no significant decrease in their radial increment. Pine trees (41 to 250 years of age at breast height) between 1884 and 1994, showed a systematic decrease in radial increment. The difference in the radial growth between younger and older generations was noticeable only in the case of beech.

The purpose of the research was to analyse the labour consumption and output of several technological processes of fuel wood chip harvesting. Potential woody biomass that can be used for energy purposes can be found in the wood that is harvested in the course of improvement cuttings and final fellings. Therefore the processes studied were those of wood harvesting in late cleanings, early and late thinnings and final fellings. In principle, the potential of fuel wood should be sought in pine tree stands, as this species prevails in our forests. Among the technological processes analysed, the LC-PI-WS process was the most labour consuming one, with labour consumption reaching 4.76 h/m³. The most labour consuming technological operation in this process was delimbing with an axe (2.44 h/m³) and horse skidding on a strip road (1 h/m³). The least labour consuming operation was chipping with a DVWB 112 disc chipper mounted on a Ursus 1204 tractor (labour consumption 0.13 h/m³). The process of machine wood harvesting in final felling (FF-PI-CW-M) was the least labour consuming one.

Investigations were conducted at five oak experimental areas, established in 1952, 1968 and 1995 as mixed, nest and row croplands in the surface of complete clearance. It was found that in each of the areas the species composition and the size of the populations of individual species of mites differed. However, the dominant mite species in the pine area still remain dominant in experimental areas, although at different proportions. It suggests that probably mites primarily migrated from the neighboring pine tree stands to the newly established experimental areas. Moreover, it was shown that in the pine area the percentage of mites from the family Parasitidae was definitely the highest and the imbalance between the percentage of mites from the family Parasitidae and those from the suborder Uropodina was the biggest. On the other hand, in the experimental oak tree stands the populations of species did not differ so much in size.

Studies were carry out to work out a protocol for in vitro propagation of Krotoszyn oak using half of acorn. The focus of the study was to select the best medium and concentration growth hormones for oak multiplication. The highest average multiplication was observed on WPM supplemented with 2.0 mg/l BA+ 0.01 mg/l NAA.

Hedera helix L. covers an area of about 46.800 m² in forest division 48b of the “Puszczykowskie Góry” strict protection area. 170 ivy shoots climbing 14 species of trees and shrubs were noted, 20 of which bloomed and bore fruit. A morphological description of the ivy was made. A total of 12 quantitative characteristics of leaves, flowers, inflorescences, and fruits were analysed. It appears here in four plant communities. The research shows the examined population of Hedera helix to be in good condition.

The study investigated the effect of the action of air with increased humidity contents and cyclic changes in humidity on the properties of OSB/4 boards glued in the centre layer with PMDI resin. The research results show that OSB/4 boards used for the purpose of the study are characterized by very high values of the modulus of rupture and modulus of elasticity. The long-term action of air with the humidity of 90%, as well as cyclic changes in humidity result in only a slight decrease in these values. The boards meet the requirements of the PN-EN 300 standard in terms of internal bond after the boil test. However, their water-resistance measured with this parameter does not comply with the standard requirements after 9-week seasoning in the air with the humidity of 90% and after three cycles of the action of the air with changeable humidity. The long-term action of air with both increased and changeable humidity results in a durable deformation in the thickness of OSB/4 boards reaching 8%.

The charring rate has been determined for specimen of pine (Pinus sylvestris) and oak (Quercus pedunculata) treated with two inorganic and organic chemicals, known in Poland as effective fire retardant. Received data were compared with data for untreated wood. It has been observed, that the charring rate was reduced by 15-24% for impregnated pine and 12-20% for impregnated oak (Ogniochron). The charring rate was reduced by 9-27% for Fireclear.