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The effect of moisture content of firewood using the energy efficiency model of low and medium temperature processing boilers with the power input up to 500 kW is analysed in the paper. The results of the effect of moisture content of burnt wood with the moisture content in the range W = 10–60% on boiler energy efficiency during cooling the flue gas in a boiler at the temperature ranging from t = 120 °C to 250 °C and emission production with the concentration of CO = 2500 mg.m-3 and soot TZLC = 150 mg.m-3 associated with the boiler requirements of Class 3 in accordance with the standard EN 303:2012 are presented. Following the analyses, the fact that the energy efficiency of a boiler decreases from η = 89.81% to η = 82.95% due to increase in the moisture content of wood from w = 10% to 60% while flue gas is cooled to the temperature of t = 120 °C can be observed. When the flue gas is cooled to the temperature of t = 250 °C, there is decrease in energy efficiency from η = 79.25% to η = 64.58%. Negative effect of moisture content of burnt wood on the boiler energy efficiency depending upon the moisture content of firewood and the temperature of flue gas is described using the formula: η = [(-0.0027∙W2 + 0.0564∙W + 89.373) – (0,001∙W + 0.068)∙(tsp – 120)].
In Central Europe, the dynamics of mountain forests has been for a long time most influenced by wind storms. The aim of this study was to obtain knowledge about the structure and dynamics of secondary succession in extreme climatic mountain conditions on disturbed areas after the Kyrill Hurricane in the eastern part of the Krkonoše Mts, Czech Republic. Density, tree species and growth parameters of natural regeneration and game damage were monitored in period 2007–2018 on three localities on comparable fourteen research plots. In 2007, average number of natural regeneration reached 2,167 recruits ha-1, and 3,637 recruits ha-1 in 2018. Results showed density increase of dominant Norway spruce (Picea abies [L.] Karst.; by 65%) and the significant upturn of deciduous tree species (by 334%), especially in rowan (Sorbus aucuparia L.) during the observed period. In tree species composition, spruce share decreased from 98.4% to 92.9% in favor of deciduous tree species. In 2018, rowan, goat willow (Salix caprea L.) and silver birch (Betula pendula Roth.) accounted 1.0–22.5% of composition. In terms of height structure, the average recruit height was 44.2 cm (± 35.7 SD) in 2009 and 219.2 cm (± 135.3 SD) in 2018 with low increment in 2011, 2017 and 2018. The study also confirmed the negative influence of Calamagrostis villosa on density of the natural regeneration and positive effect of decreasing altitude and increasing slope on height increment of natural regeneration. Moreover, ungulate was significant limiting factor of growth of regeneration (31.9% damage by browsing), especially for willow and rowan (100% damage).
Norway spruce (Picea abies L. Karst) is economically very important tree species. On the other hand, mainly due to climate change, spruce is considered to be problematic and unpromising in many regions. Spruces are endangered by a wide variety of harmful agents, including abiotic, mechanically acting agents (snow, rime and especially wind). In this paper, knowledge focused on possibilities of increasing the static stability (resistance to wind) of spruce stands is synthesized. It deals mainly with their tending based on target trees method approaches. Following the graphicons of static stability of spruce stands, results from verification of resistance of stands raised by this method are presented. The slenderness ratio (tree height to stem diameter ratio) and the crown proportion (crown length to tree height ratio) of the target trees were used as indicators for the static stability of the spruce stands. Data from long-term research activities on permanent plots located in a substantial part of the territory with natural occurrence of spruce in Slovakia were used as testing material. Research results indicate that trees with a favourable degree of static stability can be achieved in spruce forests by implementing the method of target trees. Finally, we propose measures how to apply the theoretical results of this work in forestry practice, namely in the planning and forest silviculture operations.
The objective of the paper is to analyse the issue of forest land valuation from its origin till the present with the emphasis upon detected differences between its deterministic and stochastic models considering their necessary innovations. At present, there are only deterministic methods for these purposes largely used in practice, despite the increasing risk of natural hazards occurrence within forestry induced by ongoing climate change. Several case studies inform that the observed impact of this risk on the forest land value is strong and can even lead to the infeasibility of forestry. Moreover, the results of deterministic calculations cannot serve as the correct measure of balance approached between supply and demand in the land market. The proposed innovation of methods concerning calculating the forest land expectation value is based on the introduction of procedures that take the risk of detrimental natural hazards occurrence into account. This means that mentioned deterministic models based on the Faustmann formula should be replaced by their stochastic counterparts, especially under conditions where the detected specific risk of forest management approaches the significant levels. The paper presents the list of references to prospective solutions on how to introduce these advanced forest valuation methods in practice.
Presented study evaluates the effect of regeneration felling on the nest-site occupancy of the Northern goshawk (Accipiter gentilis L.) at seven sites in the Chřiby Hills of southeastern Moravia (Czech Republic) between 2000 and 2018. The study used GIS to monitor a series of 1-km circles (an area of 78.5 ha) around nesting trees, measuring the size of regeneration patches and their distances from nests. The aim of the study was to determine the effect of nearby clearcutting on nest-site occupancy. The results show that the goshawk’s nesting patterns were mainly affected by gradually developed regeneration patches, which together began to turn into large clearcut areas. The key factor was the distance of these regeneration patches from the nest – distances less than 80 m prevented the goshawk from nesting under the given conditions. However, depending on the size of the regeneration patch, even a distance of 120 m prevented nesting. Such results indicate that regeneration management in the form of small and irregularly placed clearcut patches would be less disruptive for the goshawk’s nesting habits than standard clearcutting management with successive adjacent clearings (up to 1 ha) forming an ever larger area.
The work deals with the evaluation of three Norway spruce provenance research plots within the age 40–50 years. Totally, 65 provenances from several regions of Norway spruce were measured at two different altitudes (North Moravia) and under the conditions of former air pollution load (North Bohemia). The plots are part of the GDR–CSR 1972/76-77 series established in cross-border cooperation with Germany. The evaluation included heights, DBH, defoliation, stem form, stem damage and health state. The best volume production was achieved in both research plots by provenances of German origin, namely 41 Hainsbach (Červená Voda research plot) and 39 Bütterbächel (Mnichov), whose origin altitudes roughly correspond to the altitudes of the research plots on that they proved successful. With the exception of two Austrian provenances (49 Granitz, 50 Fastenberg) on the Červená Voda plot, the provenances from Belarus and Austria show the slowest growth on research plots Červená Voda and Mnichov. The fastest growths show the provenances from Poland with one exception (59 Borki) on the plot Červená Voda and one exception (58 Iłava) on the plot Mnichov. Czech, Slovak and German provenances growth intensity was mostly moderate or slightly above average. Two homogeneous groups according to origin have been differed: (1) Alpine, Rhodopean and Russian-Scandinavian, (2) Hercynian-Carpathian. The best growth performance appeared in the provenances of the Hercynian-Carpathian sub-region, the worst in the North-European provenances.
Nature conservation policy is restricting the active forest management in protected areas. This paper describes current issues related to the forestry in the protected areas of the Slovak Republic. Major conflicts follow from different approaches to the forest management, biodiversity protection, ecosystem services, and property rights. Specific disputes can be resolved, but these political conflicts are complex and permanent, linked to social, cultural, economic and scientific aspects. Based on the theory, for those cases the „conflict management“ approach is used for the mitigation of unwanted consequences. Based on analysis of policy instruments from Slovakia and approaches implemented in other European countries, an alternative conceptual model of policy instruments was proposed to mitigate wood production and nature conservation conflicts. The intention of the model is to unlock the potential of forests in protected areas within the goals of the green economy. Evaluation of tree species composition and comparison of costs required for the forest regeneration between really used and model species composition in the areas affected by spruce dieback.
Large forested areas exhibit a Norway spruce dieback in the Czech Republic. Foresters being faced this disaster need to change tree species composition of new stands. The objective of this study is the assessment of forest regeneration costs at study sites in Northern and Central Moravia (Czech Republic) investigated in 2008–2017. For that purpose we used the data recorded by the state enterprise Forests of the Czech Republic, including information about operations carried out in the regenerated stands that led to their establishment. The data were also divided according to ecological series and certain forest altitudinal zone. Based on the output standards we calculated the regeneration costs including the following silvicultural treatment of the really used species composition, and the costs of a potential regeneration and the following silvicultural treatment of the model species composition comparable with the target tree composition. The results confirmed higher costs on site regeneration where the species composition is more varied and supports ecological stability. However, this species composition requires a more intensive forest management than model species composition favouring mostly Norway spruce.