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Natural regeneration is a crucial factor in improving the economy of forest estates. The presented study analysed the economic parameters of three different approaches to forest regeneration: (i) artificial regeneration with Norway spruce, (ii) a 25% admixture of soil-improving and stabilising species (SSTS), and (iii) natural regeneration. The expenses for these specific operations related to individual regeneration methods were derived. These variants were investigated before the bark beetle calamity (2014) and after the outbreak (2023) for management sets (MS) 531, 551, 571, and 591, i.e. for acidic, nutrient-rich, gleyed, and waterlogged sites of higher elevations. In all cases, natural regeneration decreased expenses by approximately 2 000 EUR·ha-1 (50 000 CZK·ha-1) to 6 000 EUR·ha-1 (150 000 CZK·ha-1). The 25% admixture of SSTS increased the expenses. The proportion of natural regeneration subsequently decreased due to the bark beetle calamity from roughly 40% to 10% in recent years, which is comparable with the Czech Republic as a whole. [ABSTRACT FROM AUTHOR]

Seeds of forest species can show germination and survival problems if they are exposed to adverse climatic conditions in the course of germination. Brassinosteroids could help seeds to overcome such environmental stress. We tested the effects of exogenous application of a chosen brassinosteroid compound 2α,3α,17β-trihydroxy-5α-androstan-6-one on the germination capacity and germination energy of European black pine (Pinus nigra J. F. Arnold) seeds. Before germination, the seeds were soaked for 24 hours either in demineralised water (control treatment) or in brassinosteroid solutions of four concentrations (high, higher-medium, lower-medium and low-concentration treatments). In the course of germination, the control and all four concentration treatments were subjected to two alternative temperature regimes: the optimal (unstressed) regime (20/30°C) and the stress regime, during which the seeds were exposed to temporary temperature stress (peaking at 42°C). In the optimal temperature regime, the highest germination energy was recorded in the higher-medium-concentration treatment and a significantly increased germination energy when compared to the control was also observed in a highconcentration treatment. The brassinosteroid, when applied in high, highermedium and lower-medium concentrations, significantly increased the germination capacity compared to the control. The highest germination capacity was recorded in the high-concentration treatment. The temperature stress substantially reduced the germination of P. nigra. In the stress regime, the seeds of the higher-medium-concentration treatment decidedly showed the highest germination energy and capacity and those of the control treatment the lowest. The seed germination energy in the control was significantly lower than that recorded in the high and higher-medium-concentration treatments. The seed germination capacity in the control was significantly lower than those found in all concentration treatments, except for the seeds in the lowconcentration treatment. The brassinosteroid application promoted the germination of black pine and partly alleviated the impact of the temporary heat stress. However, this application did not compensate for the heat stress effects completely. The potential for the use of the brassinosteroid may exist chiefly for seedings of Pinus nigra in forest nurseries where the nursery staff try to maintain optimal climatic conditions, and deviations from these conditions are usually only temporary. [ABSTRACT FROM AUTHOR]

The state of upper horizons of forest soils under forest stand groups of silver fir (Abies alba Mill.) and Norway spruce (Picea abies /L./ Karst.) was compared in the same site conditions. The study was performed on the site characterized as oak-fir with Luzula nemorosa, soils were determined as Luvisols, altitude 420–440 m a.s.l. Upper soil horizons (L+F1, F2+H, Ah and B) were sampled in five replications, holorganic horizons quantitatively. The amount of surface humus as well as basic pedochemic characteristics were determined: pH, soil adsorption complex characteristics, exchangeable acidity, the content of total carbon and nitrogen, and content of total and plant available macronutrients. The cellulolytic potential of H and Ah horizons was determined in a laboratory experiment. Results confirmed only mild effects of silver fir on the soil chemistry: soil reaction, base saturation, and especially on nitrogen content and C/N ratio. Basic elements content was slightly affected as well. No visible effects of fir on the cellulolytic activity were detected. Silver fir, compared to Norway spruce, showed only minor soil improving function. [ABSTRACT FROM AUTHOR]

This paper deals with the evaluation of the effect of afforestation of previously arable land to soil characteristics changes. One of the main aims was to evaluate the effects of each forest species on the soil structure quality after afforestation. Soil samples were taken at two climatically distinct subregions within the Czech Republic. Based on the different site conditions, two study sites were chosen at each locality for a total of four research sites. Detailed soil survey and basic forest stand inventories were conducted at all four sites. The first locality was established in the Rychnov nad Kněžnou district in the Protected Landscape Area of the Orlické mountains (soil type a Haplic Cambisol). The second locality was established in the Prague-East district (soil type a Haplic Cambisol and a Haplic Stagnosol). Afforestation had a positive influence on the soil physical characteristics which are important for the maintenance of soil stability. Forest cover has a major influence on increasing the soil porosity, by decreasing the reduced bulk density and increasing capillary and gravitational pores, which is crucial. Afforestation was also found to be positively related to increases in soil organic matter content in different forms, both stable and unstable, and tendency of considerable soil organic matter accumulation not only in the layer of surface humus but also in the entire soil profiles of the research sites. The main contributor to soil improvement after afforestation is the formation of stable soil aggregates. This is typical also for spruce and pine cover.

In the context of global change, the integration of non-native tree (NNT) species into European forestry is increasingly being discussed. The ecological consequences of increasing use or spread of NNTs in European forests are highly uncertain, as the scientific evidence is either constraint to results from case studies with limited spatial extent, or concerns global assessments that lack focus on European NNTs. For either case, generalisations on European NNTs are challenging to draw. Here we compile data on the impacts of seven important NNTs (Acacia dealbata, Ailanthus altissima, Eucalyptus globulus, Prunus serotina, Pseudotsuga menziesii, Quercus rubra, Robinia pseudoacacia) on physical and chemical soil properties and diversity attributes in Europe, and summarise commonalities and differences. From a total of 103 publications considered, studies on diversity attributes were overall more frequent than studies on soil properties. The effects on soil properties varied greatly among tree species and depended on the respective soil property. Overall, increasing (45%) and decreasing (45%) impacts on soil occurred with similar frequency. In contrast, decreasing impacts on biodiversity were much more frequent (66%) than increasing ones (24%). Species phylogenetically distant from European tree species, such as Acacia dealbata, Eucalyptus globulus and Ailanthus altissima, showed the strongest decreasing impacts on biodiversity. Our results suggest that forest managers should be cautious in using NNTs, as a majority of NNT stands host fewer species when compared with native tree species or ecosystems, likely reflected in changes in biotic interactions and ecosystem functions. The high variability of impacts suggests that individual NNTs should be assessed separately, but NNTs that lack European relatives should be used with particular caution. [ABSTRACT FROM AUTHOR]

Black walnut (Juglans nigra L.) is an introduced north-American species with highly valuated timber. In the Czech Republic, it occupies cca 1,000 ha only, particularly in the flood-plain area of south Moravia. Comparing to native tree species, black walnut shows high volume and value production. On the contrary, it is exposed to pressure from the part of environmentalist organizations, due to growth at the valuable sites. Aim of the presented study is the summarization of available data from abroad as well as from the Czech Republic, to gather information concerning the production potential and environmental effects of this species in Czech conditions. The study summarizes literature sources concerning volume and volume production as well as the available data on environmental effects, especially effects of black walnut on the plant communities in the forest ecosystems. Results document the excellent production potential of this species in proper conditions and conditions for minimizing risks for the forest environment. More attention should be paid to this species in the Czech conditions, its position in the Czech forestry should increase in restricted controlled extent. [ABSTRACT FROM AUTHOR]

Paper documents the effects of grand fir (Abies grandis /Dougl. ex D.Don/ Lindl) on the basic characteristics of the soil chemistry and nutrient dynamics. The amount of the surface humus and basic chemical characteristics of the horizons F+H, Ah, Bv (soil pH, soil adsorption complex characteristics, total carbon and nitrogen content, C/N ratio, exchangeable acidity characteristics, plant available and total nutrient contents) were compared at two localities in young stands (38 years) of grand fir, Norway spruce and European beech on the territory of the Central Bohemia (altitude 340 and 435 m a. s. l., mean annual precipitation 660 mm, mean annual temperature 876;C, fresh to waterlogged oak-beech and beech sites). Results documented relatively slight differences among stands as a result of different species cultivation. Th is was determined by the site conditions and young age of particular stands. However, some positive effects of the grand fir were visible and relevant, especially higher soil reaction and soil adsorption complex characteristics. Forestry research should bring this species into focus more frequently. [ABSTRACT FROM AUTHOR]