Effective and environmentally friendly methods of protection to reduce seed contamination from fungi are constantly sought. The use of thermal impulses of 100 °C wet water steam to reduce fungal contamination has not been sufficiently investigated, and the potential of this physical approach has not been estimated.The aim of the study was to investigate what impact 100 °C wet water steam with different time durations had on acorn contamination with fungi, acorn germination and biometric indicators of English oak (Quercus robur) seedlings during the first year of growth. Different treatment durations with wet water steam were used: 2, 4, 6, 8, 10, 12 and 14 s.Research showed that 6 seconds impact of wet steam on the surface of the oak acorn destroyed Alternaria spp., 8 seconds impact destroyed Penicillium spp. and 14 seconds impact destroyed Mucor spp. Using 14 seconds water steam treatment Penicillium, Alternaria and Mucor spp. fungi were eliminated.Wet water steam treatment for 2 - 4 seconds not only stimulated the acorns germination by 4.0 - 7.6%, but also had positive influence on the root collar diameter of seedlings. Wet water steam treatment for 2 - 12 seconds had a positive effect on the root development of oak seedlings, however, high temperature environment had a suppressive effect on the oak seedling height. Keywords: biological control, wet water steam, fungi, oak acorns, seedling production

The aim of this study was to assess the quality of Scots pine (Pinus sylvestris L.) wood depending on the age of trees, forest site conditions and social class of tree position in the stand. Analyses were based on the determination of specific density and static bending strength, as well as the strength quality coefficient. It was to determine changes in physical and mechanical properties of timber depending on tree age as well as growth conditions reflected in the forest site such as fresh mixed coniferous forests and fresh mixed broadleaved forests. Experimental plots were established in 6 localities with 30, 40 and 60-year-old trees. In each of the stands, a 1-hectare experimental plot was established. Based on the measured DBH and tree height, dimensions of three mean sample trees were calculated, while the classification of social class of tree position in the stand developed by Kraft (1884) was also applied. Analyses were conducted on wood samples with 12% moisture content. Strength tests on wood samples were performed on an Instron 33RH204 universal strength testing machine. A detailed analysis showed properties of pine wood are improved with an increase of tree age in both forest sites. Statistically significant differences were observed for wood density and static bending strength. More advantageous properties were observed for wood of pines from the less fertile forest site, i.e., fresh mixed coniferous forests. Density and static bending strength were markedly determined by tree age and growth conditions. The static bending strength quality coefficient from pines growing in the fresh mixed coniferous forests increased between 30 and 40 years, similarly as it was for the fresh mixed broadleaved forests, while between 40 and 60 years, it deteriorated for the fresh mixed coniferous forests. Wood density from the fresh mixed coniferous forests was by 3% to 7% greater than pines growing in fresh mixed broadleaved forests. In turn, static bending strength of wood from pines growing in fresh mixed coniferous forests was by 4% to 10% greater than trees from the fresh mixed broadleaved forests.  Keywords: Scots pine, wood properties, forest site, Poland

Forest ecosystems face challenges of climate change and the pressure of economic activity on biodiversity. As European policies turn into Green Deal, ecological forestry systems, which aim to increase or at least not reduce biodiversity while maintaining high forest productivity, are becoming particularly relevant. This study examines distribution regularities of the lower storeys of main tree species in fertile not wet habitats of forest communities composed of pioneer deciduous tree species, the understanding of which will allow the development of forestry systems that exploit the natural forest regeneration potential. We used stand-wise forest inventory data on Betula spp., Populus tremula, Alnus incana mature and overmatured stands. We analysed how lower storeys are distributed in the stands of different tree species according to soil conditions, the age, stocking level and mixture. We found that most of stands are not in the second story and understory, from which new stands can be formed. Betula forests have the greatest potential for regeneration, and Alnus incana forests have the lowest one. The most important species of the second story and understory is Picea abies, rarer Fraxinus excelsior and Tilia cordata, other species are more random. With an increasing forest mixture, the second story and understory are found more often. To reduce clear-cutting in the fertile forests of pioneer tree species in forestry, we need to focus on measures to allow the development of lower storeys of the major climax tree species. Keywords: ecological forestry, forest succession, fertile site type, pioneer tree stands, temperate hemiboreal forests.

Forest fire is an uncontrolled combustion of flammable materials in forested and non-forested areas. In Lithuania forest fires mainly occur in late spring and summer, mostly in young coniferous forests (Forest ..., 1987). The studies of herbaceous plants in fireplaces were carried out in 2016 in Jurbarkas SFE. Ground-level forest fire increased the projection coverage of herbaceous plants and their species composition in the fireplaces. According to the average data of the survey, 18 herbaceous plant species were ascertained in the fireplace and 14 species in the control stand. During the first year after fire, 9 new species were recorded in the fireplace and 5 species have disappeared, while in the seventh year -7 new species were recorded and 1 disappeared, as compared with the control stand. Summarizing the obtained data it can be stated that low-intensity ground-level forest fire in pine forest increased the number of herbaceous plant species, however, the number of new and extinct species has been gradually decreasing, suggesting that in the fireplaces the diversity of herbaceous plant species will be like in the control stand.

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