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Risk assessment on geodiversity sites
No full textGeoconservation is an action of conserving and enhancing geological, geomorphological, hydrological and soil features and processes. Particular geoconservation measures are very often applied on the site-level to protect important geodiversity sites. Nevertheless, despite established legal protection and related geoconservation activities, threats to geodiversity sites related to the multiple use and human society demands can arise and reaching a compromise can be difficult. In this contribution, a two-level threat assessment is applied and discussed. The first level of threat assessment is based on the already used criteria within geosite/geomorphosite concept. The second level of threat assessment is represented by Risk Assessment Matrix, which may be considered a useful tool providing a complex view on the threats to geodiversity sites. The methods are applied on two different sites and their advantages and limits are discussed. Based on the assessment, specific management proposals may be implemented in order to balance conservation needs and demands resulting from human activities related to the sites.Published Versio
Revitalisation of drained forest area
No full textThe article deals with a possible way of revitalisation of the drainage system established in the past in the locality "Křížovna" in the cadastral area of Čejkov in the Vysočina region. The area is located at an altitude of 649 - 657 m above sea level, the affected area is 1.33 ha and has the character of a spring area. Currently, there is a mixed forest with a predominance of conifers of approximately 50 - 100 years of age. In the past, the site was drained by a system of ditches which were connected to a sunken unnamed stream. In the context of ongoing climate change, the drainage system has lost its purpose. It is desirable to retain water rather than to facilitate its accelerated runoff. Revitalisation measures of a purely natural manners have been implemented using local materials. Simple types of measures have been used to create, among other things, pools, loosened flow paths, cross dams, etc. The text describes the individual types of solutions. In the design process, the individual measures were sensitively chosen so as to minimise interference with mature vegetation. The technical element was the implementation of a ford on the existing logging road and the reconstruction of a culvert under the forest road. The revitalisation measures aim to initiate naturalisation processes both in the stream bed and in the ditches.Published Versio
Different Drought Tolerance Strategy of Wheat Varieties in Spike Architecture
Get PDFSpike characteristics include spike length, total spikelet number per spike, number of fertile flowers, spike density, spike fertility, grain number, thousand kernel weight, the number of spikes per square meter, harvest index and the grain yield during the flowering and ripening stage. The six winter and one facultative variety differed in earliness, derived in part from the allele of the Ppd-D1 gene and phenological observation. The two sites significantly differed in the soil moisture, which varied during continual microclimate monitoring. The spike architecture of winter wheat was affected by drought. The plant samples from the site FIELD 2 (more drought stressed) showed a higher reduction in spike characteristics such as a lower spike length, total spikelet number, number of fertile flowers and spike fertility, leading to a lower yield than the site FIELD 1. Both early and late varieties possess compensatory abilities to create the grain yield during drought stress; however, the timing and duration of exposure to drought determine the application and success of the compensatory ability. In our experiment, the late varieties (photoperiod sensitive) performed better in yield than the early varieties during both growing seasons. That is at odds with the generally recommended "drought escape strategy" (early varieties) and suggests a possible direction for variety selection and breeding in arid areas in Central Europe.O
Evaluation of parameters influencing the withdrawal strength of oak and beech dowels
Get PDFThe withdrawal strength of plain dowels with nominal diameter of 8 mm was compared with the spiral dowels manufactured from beech (Fagus sylvatica L.) and oak wood (Quercus robur L.). The test specimens were tested after conditioning at relative humidity (RH) 25%, 45%, 65%, and 85% at a constant temperature of 20 oC. Therefore, the influence of relative humidity (respective moisture content), dowel structure, and wood species of the dowels on the withdrawal strength was determined. The structure and low humidity (RH 25%) caused the highest strength (8.6 MPa) of spiral dowels. Compared to plain dowels, the higher withdrawal strength of spiral dowels was statistically significant. Adversely, the lowest withdrawal strength was found for plain beech dowels (3 MPa), which, in addition to higher relative humidity (RH 85%), was also caused by a combination of plain structure and greater diameter of the dowels, thereby decreasing the amount of adhesive in the bonded joint. The influence of the wood species of the dowels was not statistically significant overall.O
The Protection of Ash Trees Against Ash Dieback by Tree Injections
No full textAsh dieback caused by a non-native pathogenic fungus Hymenoscyphus fraxineus has been decimating populations of European Fraxinus species for over 30 years. Nevertheless, there is still a considerable amount of valuable ashes of this species in European cities and landscapes. Although it has been shown in many studies that the effect of H. fraxineus on adult and senescent trees tends to be rather chronic, the infection by this fungus also causes a substantial decrease in the lifespan of these trees. This research is dealing with the control of ashes using the tree injection technology. It is focused on the development of bark necroses, as this symptom results in the highest damage to a tree. Trees were first inoculated with two different strains of H. fraxineus. Trees with proven positive inoculation were injected with six different fungicides. Subsequently, over the course of nine months, the area of developing bark necroses was measured using image analysis methods. After the field part of the experiment was finished, the extent of the infection by H. fraxineus in tissues was determined and confirmed by PCR. Three out of six tested variants (Tr. 1: 7.1% propiconazole, Tr. 3: 7% propamocarb and 2.7% fosetyl, and Tr. 6: 0.015% sodium selenite) displayed significant deceleration of the growth of bark necroses compared to control. Tr. 3 demonstrated the highest effectiveness with only a very small increment of the necrosis area during the first three months after the injection treatment and a follow-up complete cessation of growth. Reisolations confirmed high mortality of H. fraxineus after this treatment. Hence the presented study can contribute to substantial prolongation of the lifespan of ashes in Europe.Preprin
Impact of thermal modification on color and chemical changes of African padauk, merbau, mahogany, and iroko wood species
Get PDFThermal modification is an environment-friendly technology for improving various wood properties, especially the dimensional stability, decay resistance, and color homogeneity. In this work, four tropical wood species (African padauk, merbau, mahogany, and iroko) were thermally modified by the ThermoWood process. The influence of heat treatment on the color and chemical changes of wood was studied by spectrophotometry, Fourier transform infrared (FTIR) spectroscopy, and wet chemistry methods. As the temperature increased, a decrease in lightness (L*) and a simultaneous decrease in chromatic values (a*, b*) were observed, indicating darkening and browning of the wood surface. As a result of the heat treatment, the relative content of hemicelluloses decreased the most in merbau and mahogany, while the thermal stability of iroko and African padauk was higher. All examined wood species showed a strong correlation between the lightness difference value (ΔL*) and the content of hemicelluloses (r = 0.88-0.96). The FTIR spectroscopy showed that the breakdown of C═O and C═C bonds in hemicelluloses and lignin plays an important role in the formation of chromophoric structures responsible for the color changes in the wood.O
Is a new generation of mycotoxin clay adsorbents safe in a pig's diet?
Get PDFBackground: Bentonites, as a clay mineral, serve in pig farms as adsorbents of toxic substances. They are mainly used to reduce the negative impact of mycotoxins to maintain the performance and health status of animals. The new genotypes of pigs are highly sensitive to a range of antinutrients, including mycotoxins. Currently, attention is focused on more effective adsorbents of mycotoxins with a higher adsorption capacity. Such materials are in great demand among feed manufacturers. However, there is a concern that these new materials may also adsorb too many essential nutrients and decrease animal performance. The aim of the experiment was to evaluate the effect of the new generation of purified bentonites on the efficiency and health status of the pigs. Results: Forty-eight slaughtered pigs with an average weight of 31.2 +- 2.6 kg were included in the experiment. The pigs were divided into two groups (2 x 24 pigs). Pigs were slaughtered at an average weight of 66.3 +- 5.2. The first group had a diet without clay (control-C). The second group (treatment-T) was fed a diet with a clay additive (purified bentonite) of 1.5 kg/t. Animals were fed the experimental diet for 35 days. In group T, a higher daily weight gain (by 4.8%) and feed intake (by 2.9%) was observed while the feed conversion decreased by 1.9%. There were no significant differences between the groups of pigs during observation in the evaluation of hematological, biochemical parameters of the blood. Morpho-pathological analysis of the jejunum showed similar signs of moderate lymphoplasmacytic infiltrate in the mucosa in the groups C and T, contained similar number of goblet cells. Conclusion: Taken together, the addition of the new generation of bentonite clays did not negatively influence the health status and the performance of pigs.O
Are the Agricultural Subsidies Based on the Farm Size Justified? Empirical Evidence from the Czech Republic
Get PDFThe paper aims to explore the relationship between size, production orientation, and performance in the Czech agriculture and to answer the research question as to what extent a farm size and a product orientation of farm do matter in relation to its productivity and profitability. We use data from FADN CZ database (Farm Accountancy Data Network-Czech Republic) of conventional farms oriented on fieldcrops production, milk production, other grazing livestock and mixed production, and we cover the period from 2015-2020. Pursuing an econometric approach (ANOVA and multivariate regression analysis), we test productivity and profitability differentiation among the different-sized and different production orientation companies. Finally, subsidies and their effects on different groups of companies are assessed. The findings from testing our empirical model indicate that very large farms have statistically significantly higher total factor productivity than large farms, which perform better than medium and small farms. Average productivity of large-size farms compared to small and medium farms is 1.4 times higher in terms of total factor productivity, more than two times higher in terms of agricultural land productivity, and 3.2 times higher in terms of labour productivity. The findings show that farms with field production statistically significantly outperform farms with orientation on other grazing livestock and mixed production. Different levels of productivity are translated into differentiation in the profitability. The highest profitability ratios are achieved by large farms followed by very large, medium, and small ones. The assessment of ratio of subsidies to agricultural production shows that small farms received 2.3 times higher agricultural subsidies per unit of agricultural production compared to very large farms.O
Non-Indigenous Cladocera (Crustacea: Branchiopoda): From a Few Notorious Cases to a Potential Global Faunal Mixing in Aquatic Ecosystems
Get PDFNon-indigenous species may pose a threat to native ecosystems worldwide. In aquatic environments, invasives may have a negative impact on human food security and livelihoods. Several water fleas (Crustacea: Branchiopoda: Cladocera) are notorious invasive alien species influencing large freshwater lake systems and even inland seas. In the current review, we discuss the state of knowledge regarding non-indigenous species in the Cladocera and their invasiveness potential in different continents. We argue that the potential impacts and occurrence of cladoceran exotics may be higher than generally assumed. We critically review 79 cases from literature sources, involving 61 cladoceran taxa where records outside of their natural distribution ranges were previously interpreted as invasions. We assessed the probability of natural range expansions versus human-mediated introductions and we discuss several major corridors of invasion. We estimate human-mediated transportations for at least 43 taxa (out of 61; ca 70%), while other cases can be seen as natural expansions of their distribution ranges (not necessarily/not likely human-mediated) and/or taxonomical confusion. We confirm non-indigenous presence in recipient regions for at least 41 cladoceran taxa, of which several are true invasives (i.e., with negative impacts on native ecosystems). The majority are zooplankters with effects on pelagic freshwater ecosystems, yet we also report on introductions by littoral taxa. We argue that cryptic introductions of cladocerans are taking place on a global scale, yet they remain under the radar. We highlight several striking case studies, such as the Ponto-Caspian onychopods that have invaded the Baltic Sea and the Laurentian Great Lakes, and several clones of the anomopod genera Daphnia and Bosmina that have successfully colonised new environments, causing equilibria shifts in native aquatic worlds. At the same time, we dispel some myths about taxa that were misconstrued as invasive in certain localities. Based on our review, the first of its kind for freshwater zooplankton, future environmental monitoring tools including molecular techniques and detailed surveys with rigorous and critical taxonomical assessments may help to provide a clearer picture on the extent of invasiveness of cladocerans.O
Reactive Nitrogen Species and Male Reproduction: Physiological and Pathological Aspects
Get PDFReactive nitrogen species (RNS), like reactive oxygen species (ROS), are useful for sustaining reproductive processes such as cell signaling, the regulation of hormonal biosynthesis, sperm capacitation, hyperactivation, and acrosome reaction. However, endogenous levels of RNS beyond physiological limits can impair fertility by disrupting testicular functions, reducing gonadotropin production, and compromising semen quality. Excessive RNS levels cause a variety of abnormalities in germ cells and gametes, particularly in the membranes and deoxyribonucleic acid (DNA), and severely impair the maturation and fertilization processes. Cell fragmentation and developmental blockage, usually at the two-cell stage, are also connected with imbalanced redox status of the embryo during its early developmental stage. Since high RNS levels are closely linked to male infertility and conventional semen analyses are not reliable predictors of the assisted reproductive technology (ART) outcomes for such infertility cases, it is critical to develop novel ways of assessing and treating oxidative and/or nitrosative stress-mediated male infertility. This review aims to explicate the physiological and pathological roles of RNS and their relationship with male reproduction.O