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A constitutive model considering creep damage of wood
Get PDFThe serviceability of wooden structures involves multiphysical phenomena, notably the interactions among creep, plasticity, and damage. The influence of creep on the initialization of the damage and on its growth and spread can be adjusted by an additional alpha parameter in order to take into account the coupled effect between creep and damage more properly. We integrate an orthotropic viscoelastic model, based on the generalized Kelvin chain, with an orthotropic damage model, capturing both the immediate nonlinear elastic-plastic-damage response and the time-dependent viscous response of timber. The combination of these material models is important to obtain a realistic description of wood behavior, because the timber shows an immediate nonlinear elastic-plastic-damage response, but also the time-dependent viscous response. In this paper, we algorithmize, implement, and validate the concept of 'creep damage', a phenomenon observed in wooden structures. Benchmark tests reveal two distinct patterns of damage in beech wood, immediate postload damage that evolves over time and damage that occurs and spreads during the loading period.OA-hybri
Mycorrhizal associations modify tree diversity-productivity relationships across experimental tree plantations
Get PDFDecades of studies have demonstrated links between biodiversity and ecosystem functioning, yet the generality of the relationships and the underlying mechanisms remain unclear, especially for forest ecosystems. Using 11 tree-diversity experiments, we tested tree species richness-community productivity relationships and the role of arbuscular (AM) or ectomycorrhizal (ECM) fungal-associated tree species in these relationships. Tree species richness had a positive effect on community productivity across experiments, modified by the diversity of tree mycorrhizal associations. In communities with both AM and ECM trees, species richness showed positive effects on community productivity, which could have resulted from complementarity between AM and ECM trees. Moreover, both AM and ECM trees were more productive in mixed communities with both AM and ECM trees than in communities assembled by their own mycorrhizal type of trees. In communities containing only ECM trees, species richness had a significant positive effect on productivity, whereas species richness did not show any significant effects on productivity in communities containing only AM trees. Our study provides novel explanations for variations in diversity-productivity relationships by suggesting that tree-mycorrhiza interactions can shape productivity in mixed-species forest ecosystems.OA-hybri
Ranking of European Universities by DEA-Based Sustainability Indicator
Get PDFThe paper introduces a novel approach to university rankings that considers a university's contribution to sustainable development. It addresses the usual controversies surrounding the construction of rankings using composite indicators. The conventional approach typically involves normalizing sub-indicators and applying subjective weights for aggregation, which raises concerns about the reliability of the rankings. In response to this issue, we propose an alternative method based on Data Envelopment Analysis (DEA) that utilizes flexible weights. Our approach is applied to the data from the UI-GreenMetric World University Ranking. We initially employ a general Benefit of the Doubt DEA model and subsequently enhance its discrimination power by computing super-efficiency. In the third model, we impose weight restrictions on sub-indicators. The results of our analysis offer valuable insights for all stakeholders, as illustrated by the implications derived for Czech universities included in the sample. Furthermore, we compare the results of universities in various European countries, establishing a connection between rankings and the fulfillment of Sustainable Development Goals (SDG) within individual countries. This research contributes to a more comprehensive understanding of the relationship between university performance, sustainability, and the associated implications for policy and benchmarking.O
Phytoplankton-zooplankton coupling in a cascade of hypertrophic fishponds
Get PDFIn Central Europe, a significant proportion of shallow lake ecosystems are represented by artificial fishponds, where phytoplankton and zooplankton are an essential part of the food web. Owing to their high fish stocks and intensive fishery management, most fishponds are now eutrophic or hypertrophic, which has had clear impacts on plankton assemblages. To obtain a better understanding of phytoplankton-zooplankton coupling in fishponds, this study examines their ecological relationships in a cascade of three small fishponds over two subsequent years. In all, 133 phytoplankton taxa were recorded, mostly chlorophytes, diatoms and euglenophytes, and 60 zooplankton taxa. Multivariate analysis revealed dissolved oxygen content, dissolved inorganic nitrogen and biochemical oxygen demand as the main factors influencing phytoplankton biomass, while the most significant environment variables affecting zooplankton composition were dissolved oxygen, phosphate concentrations and conductivity. Co-correspondence analysis revealed a significant relationship between phytoplankton and zooplankton density, with cross-correlations from 76% to 87% within the first four axes. Such a high cross-correlation denotes a strong relationship between phytoplankton and zooplankton, even within the hypertrophic conditions determining fishpond ecosystems.O
Evaluation of the Thermal Energy Potential of Waste Products from Fruit Preparation and Processing Industry
Get PDFIn the context of a changing climate and increasing efforts to use renewable energy sources and waste materials and to green the environment, new sources and technologies for energy recovery from waste are being sought. This study evaluates the possibilities of energy generation potential from waste products of fruit species used in the food processing industry. The results indicate good potential for energy use of materials from fruit processing due to low input moisture content of around 15 wt. %, an average energy lower heating value (LHV) of 16.5 MJ.kgMINUS SIGN 1, an average low ash content of 4.9% and meeting most of the emission limits of similar biofuels. Elemental analysis and combustion residue studies indicate safe operation within existing standards. The results of our analyses and experience from similar studies allow us to recommend most of the studied waste materials for energy generation use directly in processing plants at the local level.O
The effect of chelating agents on the Zn-phytoextraction potential of hemp and soil microbial activity
Get PDFBackground: Hemp (Cannabis sativa) is a crop with a wide range of uses, from the production of fiber and seeds to the secondary metabolites for medicinal purposes. In addition, it is characterized by high biomass yield and the ability to accumulate heavy metals, which makes this plant convenient for phytoremediation purposes. In this study, the effect of applying exogenous biodegradable chelating agents, citric acid (CA) and nitrilotriacetic acid (NTA), to zinc-contaminated soil on zinc (Zn) uptake by two industrial hemp varieties 'Felina 32' and 'Monoica' was studied. The effect of CA and NTA on available Zn in soils was investigated using an 'in pot' experiment under controlled conditions. The effect of both tested compounds on soil microbial activity was simultaneously evaluated. Results: After the application of NTA at a concentration of 5 mmol LMINUS SIGN 1, a > threefold increased accumulation of Zn in the above-ground parts was recorded in the 'Felina 32' variety. In the 'Monoica' variety, the levels of Zn in the above-ground parts were increased > twofold. NTA affected the soil microbiome negatively, causing decreased enzyme activity (in 'Monoica' planted soil) and induced respiration (in 'Monoica' and especially in 'Felina 32' planted soil). On the other hand, CA application did not lead to significantly increased Zn levels in any of the studied hemp varieties. Together with CA's negative effects on some soil enzymes, CA enhanced urease activity, dehydrogenase and several respiration types for the 'Felina 32' variety and exerted less detrimental effect on the soil microbiome. No toxic effects from increased Zn uptake and accumulation in experimental plants were detected, accounting for the unchanged physiological stress markers (levels of photosynthetic pigments and proline in leaves, chlorophyll fluorescence parameters) and selected growth traits of the above-ground organs and root system. Conclusions: From the studied varieties, 'Felina 32' seems to be more suitable for Zn-phytoextraction because of its higher tolerance to increased Zn levels, higher biomass production and Zn accumulation capacity. Our results indicate the potential of using the 'Felina 32' variety in NTA-assisted Zn phytoextraction from contaminated soils.O
Evaluation of the Quality of the Housing Environment Using Multi-Criteria Analysis That Includes Energy Efficiency: A Review
Get PDFThe quality of the housing environment (HE) is an important issue that has a direct impact on the life of inhabitants. Aiming for quality in residential architecture begins with a well-designed HE, with the designing process being a value that is difficult to evaluate. Nowadays, a well-designed HE takes into account the energy efficiency of a building. An appropriate degree of thermal comfort, which is required by inhabitants, needs to be considered at the design stage. Designers can use building certification programs and multi-criteria analysis to motivate investors to construct buildings in accordance with energy efficiency requirements. These systems respond to the needs of energy efficiency, thermal comfort, sustainable heating, and ventilation. Defining ways and methods to evaluate quality in architectural projects will allow the value of the HE to be improved. For this purpose, a multi-criteria analysis of five systems that can be used to evaluate HE quality and energy efficiency in a temperate climate was conducted: (1) Building For Life 12, (2) Home Quality Mark, (3) Housing Quality Indicators, (4) Système D'évaluation De Logements (Sel), and (5) NF Habitat-NF Habitat HQE. This analysis concerned information about the systems, their applicability in practice, and the applied assessment measures. The article shows that the quality of the HE consists of specific factors that can be distinguished and indicated by evaluation systems. As a result of the carried out assessment of the housing environment, 13 original categories of building assessment criteria were defined. The results of the conducted analysis indicated that it is possible to: (i) identify factors for the improvement of HE quality; (ii) prepare objective systems for the measurement of the HE; and (iii) use such systems in practice, e.g., in the design industry, real estates, and public administration. Moreover, the systems can be used in legal regulations for updating urban policies.O
Traces of Local Adaptive Acclimatization Response in the Tracheid Anatomical Traits between Dry and Wet Mesic Norway Spruce (Picea abies) Forests in Moravia, Czech Republic?
Get PDFNorway spruce (Picea abies) forests in temperate zones are already reacting to short-term extreme summer heatwaves, threatening the vitality of trees and forest productivity, and can even lead to local and regional dieback events. Examining quantitative wood anatomy can provide helpful information in terms of understanding the physiology mechanisms and related responses of conifer trees to local environmental interactions in relation to tracheid adaptive capacity. This study analysed the tracheid functional anatomical traits (FATs) plasticity of six young Norway spruce trees growing in two mesic research plots with high annual precipitation (~43%) and air temperature differences during 2010-2017. The research plots are located in the sub-mountainous (Rájec Němčice) and mountainous (Bílý Kříž) belts of the Moravia region, Czech Republic. Vapour pressure deficit and cell wall reinforcement index (CWRI) were shown to be the most representative environmental parameters as proxies of dry conditions. Tracheid FATs indicated latewood phenological plasticity sensitivity, with more pronounced variability in the warmer and drier plots. Latewood tracheids of Norway spruce trees grown in the RAJ formed significantly thicker cell walls than BK during the studied period. The observed differences between the two research plots indicate additional support for tracheid cells' hydraulic safety against cavitation and potential traces of adaptive acclimatization response.O
Three new Carex nothospecies (Cyperaceae) discovered in the Czech Republic
Get PDFThe article presents three newly discovered interspecific hybrids of sedges found in the Czech Republic. The finds of two of them (Carex xhelenae and C. xploegii) are the result of authors' field work and subsequent revision of specimens in large institutional Czech herbaria, while the third, C. xalluvialis, was documented by a herbarium specimen in the BRNU herbarium, collected in 1998. The finds of these wetland hybrid sedges are a supplement to the treatment of the genus Carex for the Flora of the Czech Republic, Vol. 9. For each of the hybrids, a detailed morphological description compiled on the basis of Czech plants is given and the location of the voucher specimens is mentioned.O
Combined effects of rainfall-runoff events and antecedent soil moisture on runoff generation processes in an upland forested headwater area
Get PDFIn this study, we investigate the combined effect of different rainfall-runoff event types and antecedent soil moisture (ASM) on runoff processes in the headwater elementary discharge area of a small forested upland catchment. The study focuses on (i) the relationship between soil moisture thresholds and runoff gener- ation; (ii) the combined effect of ASM and tree vicinity and (iii) the relationship between different rainfall-runoff event types and different types of runoff (base- flow and stormflow). The results suggest that ASM has a strong impact on local runoff generation processes. Soil water content (35%-36%) threshold exceedance was related to stormflow runoff generation caused by the activation of quick pref- erential flow paths in the soil during storm events, especially in the upper and the deepest soil layers. At the same time, unexpected non-linear increases in baseflow runoff ratios were documented during dry, precipitation-free, periods and when the 31%-34% soil moisture threshold was exceeded, presumably due to the hydrological connection of farther slope areas during these conditions. Multiple stormflow periods, which exhibited the lowest runoff coefficient, were the most significant events in terms of water retention and soil water recharge due to increased vertical hydrological connectivity enabling more rapid transport to dee- per soil layers. However, this rainfall type occurred least often over the study period. The important role of forest stands (individual trees) in creating spatial patterns of soil moisture and preferential infiltration paths to deeper soil layers was also confirmed. These results contribute towards a better conceptualisation of hydrological behaviour in elementary headwater discharge areas and highlight the potential dangers associated with expected increases in extreme weather events.OA-hybri