Investigations of variability of trees volume on circular sample plots were conducted on 83 uneven stands with total area1127.7 ha in Forest Experimental Station in Krynica. Coefficients of volume variability were analysed with respect to species composition and phase of development. It was stated that unevenly aged forest is characterized by big variability of trees volume. The biggest influence on total variability of volume in group of stands with similar species composition has inside stand variability and only small influence variability between stands.

Research on rowan fruit from northern slopes of the Babia Góra Mt revealed a decrease in the share of dry mass and an increase in the content of zinc parallel to increasing altitude. The average content of the elements: sodium, potassium, calcium, magnesium, iron, manganese, copper and lead in the fruit from the upper forest zone was smaller than in the fruit from the lower forest zone and the dwarf pine zone.

The contents of total PCB and 7 indicatory congeners in pine bark (Pinus sylvestris L.) (at age of 17-45 years old) as well as in the soil from several forest sections of the Moracz Forest District were investigated. There were stated different contents of total PCB and analysed indicatory congeners. The highest values of total PCB in pine bark were observed in former farmlands of KPGR Przybiernów – 20.3 μg·kg^-1 d.m. and in the surroundings of Moracz village (section 619) with mean value 20.1 μg·kg^-1 d.m. The highest level of total PCB in soil (16.6 μg·kg^-1 d.m.) was also stated in section 619 near KPGR Przybiernów.

The paper presents the results of nematological, faunistical and ecological, researches in 2000-2004 in 25 forest nurseries. In the studied samples were found 52 species of nematodes from the order Tylenchida and 3 species from the order Dorylaimida, which are plant parasitic nematodes. The most frequently were occuring Filenchus misellus, Cephalenchus hexalineatus and Ditylenchus anchilisposomus. For several species the correlation between frequency of occurrence, abundance and some soil parameters were found.

The present work discusses the results of the faunistic studies over mites of Mesostigmata order made in the territory of Ujście Warty National Park (the mouth of the Warta River). The greatest number of specimens was represented by the family of Ascidae (107 specimens), Parasitidae (98) and Trematuridae (58). The most plentiful species that occurred in a collected material were T. ovalis (52 specimens), H. calcaratus (35), L. ometes (34) while in the greatest number of samples H. calcaratus (9 samples), T. ovalis (8) and T. pyri (8) were recorded.

The study presents observation results of the condition of tree crowns in 2003 in the following forest divisions: Szprotawa, Lubsko, Złoty Potok, Rudziniec, Strzelce Opolskie, Puławy, Buda Stalowska and Staszów. The total of 2250 trees were assessed and the evaluated trees were growing in pine stands of the III^rd and IV^th age class in the zone of mild, moderate and severe damages. The evaluation was based on studies performed on experimental plots with 25 trees from the main stand.

The study aims at assessing the accuracy of determining the fertility of mountain forest soils by using the Forest Soil Trophism Index (FSTI) [Bożek 2001]. To establish the magnitude of the diagnosis error, eighty soils representing different site conditions of the Western Beskid Mts were analysed for physicochemical properties. It was found that using FSTI for diagnosing site type resulted in a major error (40%) in the case of the sites located at lower elevations of the lower mountain forest zone; the error was much smaller (8%) for the sites situated at higher elevations of that zone. It is suggested that the method for calculating FSTI should be modified to reflect the actual variation observed in some properties of mountain forest soils such as the sum of exchangeable basic cations and the levels of the fractions < 0.02 mm and 0.1-0.02 mm. Modification consists in changing the ranges of the values of those properties, assumed in the original method for successive soil horizons. In addition, the fraction > 1.0 mm is omitted from the calculations. The modified method improved the accuracy of soil classification by FSTI: the error of diagnosis decreased to 25 and 3%, respectively, for the sites located at lower and higher altitudes in the lower mountain forest zone.

This communication presents preliminary results of studies on the mite fauna observed in the spruce stands of the Bucegi Massif in central Romania. In the collected material a total of 6436 specimens were found, which were classified to 62 species from 15 families. The most numerous were the species Veigaia nemorensis (1660 individuals), Leptogamasus parvulus (804) and Leptogamasus tectegynellus (694), whereas Veigaia nemorensis (224 samples), Neopodocinum mrciaki (150) and Pachyseius humeralis (150) were observed in the biggest number of samples. In the litter layer a total of 4842 specimens were found of mites belonging to 54 species, whereas in the humus layer it was 1594 specimens belonging to 47 species. The species similarity index between mite communities of the litter and humus layers was very high and amounts to over 77%.

Despite the changes caused by anthropopressure, the ’Olszak I, II’ ecological land is one of the sites with high floral values. Its diversified and rich flora consists of 570 vascular plant taxons. The land is one of the last mainstays of rare and endangered plant species. There are 182 species on the Red Lists, 176 are on the list prepared for the city of Poznań. 14 of “the special care species” are legally protected, and 10 belong to the rare and endangered species of the Wielkopolska region. On the examined area, 4 species considered extinct were discovered, and the existence of 10 dying out species was confirmed. The examined land is outstanding for the high percentage of monumental measure trees, as there are over 100 such trees. 76 most valuable nature monuments are legally protected.

The study comments the results of evaluation of degree reconstruction of different types of nurse crop stands in relation to their position: altitiude, exposition with regard to cardinal points, inclination of slope and the type of neighbourhood. The investigations were based on the results of the periodical inventory of mountain nurse crop stands occurrent in Forest Experimental Station in Krynica. In this study it was affirmed that nurse crop stands being at present 47-52 year-old, had species composition: compatible with the site in 11.6%, partly compatible with the site in 24.5%, and 64.0% of stands had species composition incompatible with the site. The most favorable changes were in larch and next in alder and pine stands. It was observed that reconstruction ran more intensively in stands situated at a higher level, on ornate slopes, close to the south expositions and in the neighbourhood with stands compatible with the site.

The research focused on the penetration depth and per cent content of PEG 400 taken up by waterlogged archaeological oak wood during 90 months’ impregnation. In samples drawn from various layers of archaeological beam, percentage of polymer was determined with the use of gel permeation chromatography (GPC). At various depths, different PEG 400 uptake and dehydration of a better-preserved, inner zone of the conserved object were observed.

Studies were made on the effect of the temperature in the conditioning chamber and the time of its action on the properties of OSB/4 glued in the inner layer with PMDI resin. The testing results showed that boards used for the purpose of the study were characterized by very good strength properties, and their values considerably exceed the requirements of the standard specification. Both the long-term action of air with increased (+60°C) and lowered (–20°C) temperature resulted in a decrease in their properties. Nevertheless, even after 12 weeks seasoning the studied boards complied with the requirements of the EN 300 standard.

The paper investigates the influence of the alkyl substituent in the alcohol group of esters of organic acids upon their effectiveness as modifiers of phenolic resin used in the production of particleboards. In the course of the research esters of ethyl, butyl and amyl alcohol were used. The modification of the phenolic resin with the applied esters results in the shortening of gel time and decrease in the activation energy of the resin. It also improves the physical and mechanical properties of particleboards. The improvement of the studied properties of particleboards is observed as the length of carbon chain of alcohol substituent and the amount of the introduced ester grow. Best results were obtained for amyl acetate used as a modifier.

The examinations were performed on the oak wood brought out in the oldest and most valuable Wielkopolska excavations i.e. in The Ostrów Tumski stronghold in Poznań and The Museum of First Piast at Lednica. The analysis of archeological sources allow to date analyze wooden materials on 10-11^th century. The estimation of degradaction state of construction elements performed with the use of microscope observations and chemical investigations revealed different content of heavy metals in comparison materials and considerable degradaction of carbohydrayte system of wood from The Ostrów Tumski in Poznań. There were found changes of content functional group and molecular mass of the most durable wooden component of wood i.e. lignin.