No (416)
Used filters
(3)
Number of found documents:
416
Published from
to
Flux footprints in different ecosystems
Macálková, Lenka; Havránková, Kateřina; Pavelka, Marian
2015 - English
Flux footprint is an upwind area where the atmospheric flux measured by an instrument is generated. Footprint size depends on measurement height, surface roughness, and atmospheric thermal stability. Our study focused on the flux footprints of four CzechGlobe ecosystem stations in a wetlands area, an agroecosystem, and young and mature spruce forests. Our aims were to prove that the sites were suitable for eddy covariance measurement and compare flux footprints under various atmospheric thermal conditions: stable, neutral, and unstable. Two computational models were used: the Kormann–Meixner (2001) and Kljun (2004)models. The outputs were processed graphically in site maps.
Keywords:
eddy covariance; flux footprints; ecosystems
Available at various institutes of the ASCR
Flux footprints in different ecosystems
Flux footprint is an upwind area where the atmospheric flux measured by an instrument is generated. Footprint size depends on measurement height, surface roughness, and atmospheric thermal stability. ...
Summer fluxes of nitrous oxide from boreal forest
Macháčová, Kateřina; Pihlatie, M.; Halmeenmäki, E.; Pavelka, Marian; Dušek, Jiří; Bäck, J.; Urban, Otmar
2015 - English
Boreal forests cover almost one-third of the global forest area, and results of soil measurements show them to be a natural source of the important greenhouse gas nitrous oxide (N2O). Nevertheless, N2O fluxes from boreal tree species have been excluded from calculations of N2O exchanges from forest ecosystems. Therefore, our objective was to quantify and scale up the N2O fluxes from stems of mature silver birch (Betula pendula), Scots pine (Pinus sylvestris), and Norway spruce (Picea abies), as well as from the forest floor of a boreal forest in Finland during June and July 2014. This study shows that boreal tree species emit N2O from their stems under natural field conditions and significantly contribute up to 8% of forest floor fluxes of N2O. Spruce trees seem to be the strongest N2O emitter among the studied tree species. Moreover, the N2O flux rates from both coniferous tree species increased with decreasing soil water content. This study highlights the necessity to include N2O fluxes from trees within the total greenhouse gas budget of forest ecosystems.
Keywords:
boreal forest; greenhouse gases; forest ecosystem; Picea abies; Pinus Silvestris
Available at various institutes of the ASCR
Summer fluxes of nitrous oxide from boreal forest
Boreal forests cover almost one-third of the global forest area, and results of soil measurements show them to be a natural source of the important greenhouse gas nitrous oxide (N2O). Nevertheless, ...
Interactive effects of UV radiation and drought on the accumulation of flavonols in selected herbs and grass in a mountain grassland ecosystem
Veselá, Barbora; Surá, Kateřina; Rajsnerová, Petra; Klem, Karel; Holub, Petr; Urban, Otmar
2015 - English
The main objective of this 4-year experiment conducted in a mountain grassland ecosystem was to investigate the interactive effects of ultraviolet (UV) treatment and drought on changes in accumulation of UV-screening compounds (flavonols) in selected herbs (Hypericum maculatum Crantz, Rumex obtusifolius L.) and grass (Agrostis tenuis Sibth.). Inasmuch as drought and UV radiation induce similar protective mechanisms, we tested the hypothesis that UV radiation and drought elicit synergistic effects on flavonol accumulation. The experimental plots were manipulated using rainout shelters enabling the exclusion and transmission of incident precipitation and UV radiation. Generally, UV and drought treatments had similar effects on flavonol accumulation. For R. obtusifolius, UV exclusion resulted in a substantial reduction of UV-screening compounds, particularly under ambient precipitation conditions, while for H. maculatum and A. tenuis UV exclusion caused only a slight reduction of flavonol content. Similarly, the drought treatment caused an increase in flavonol accumulation.
Keywords:
uv radiation; grassland ecosystem; herbs and grass
Available at various institutes of the ASCR
Interactive effects of UV radiation and drought on the accumulation of flavonols in selected herbs and grass in a mountain grassland ecosystem
The main objective of this 4-year experiment conducted in a mountain grassland ecosystem was to investigate the interactive effects of ultraviolet (UV) treatment and drought on changes in ...
Elevated temperature stimulates light-induced processes that contribute to protecting photosystem II against oxidative stress
Materová, Z.; Štroch, Michal; Holubová, I.; Sestřenková, J.; Oravec, Michal; Večeřová, Kristýna; Špunda, Vladimír
2015 - English
We focused on elucidating the impact of elevated temperature on rapid induction of zeaxanthin (Z)- dependent photoprotection in two different plant species. The dynamics of violaxanthin (V) de-epoxidation under different illumination regimes was studied together with chlorophyll a fluorescence transients in Picea abies seedlings and Arabidopsis thaliana leaves pre-acclimated to temperatures ranging from 20 to 40°C. Whereas for spruce seedlings the rapid phase of V de-epoxidation (induced by either 10 s illumination or 10 light pulses 1 s in duration at 1 min intervals) was gradually stimulated upon increasing temperatures, for A. thaliana leaves considerable acceleration of V de-epoxidation occurred only at 40°C. Moreover, only for spruce seedlings was a considerable amount of Z accumulated after 10 × 1 s illumination. Elevated temperatures stimulated rapid formation of Z-dependent non-radiative dissipation of excitation energy within photosystem II (NRD) induced by 1 s light pulses only for spruce seedlings. The possible role of a specific fatty acid composition in spruce thylakoid membrane lipids in facilitated V de-epoxidation and NRD induction at elevated temperatures is discussed.
Keywords:
plant species; Picea abies; temperatures ranging
Available at various institutes of the ASCR
Elevated temperature stimulates light-induced processes that contribute to protecting photosystem II against oxidative stress
We focused on elucidating the impact of elevated temperature on rapid induction of zeaxanthin (Z)- dependent photoprotection in two different plant species. The dynamics of violaxanthin (V) ...
Comparison of forestry reclamation and spontaneous succession from plant diversity, production, and economic perspectives
Cudlín, Ondřej; Faigl, T.; Plch, Radek; Cudlín, Pavel
2015 - English
The aim of our study was to determine whether the values of plant community diversity, the volume of wood, and the partial economic efficiency of plots left to spontaneous succession have yet reached similar values as those recorded on forestry reclaimed plots. Six forestry reclaimed plots and six plots with spontaneous succession were established at the Great Podkrušnohorská spoil heap and selected tree biometric characteristics were measured. Plots’ economic efficiency was calculated as the difference between the costs to level the spoil heap as well as establish and manage the forest reclamation and the theoretical profit from wood. The numbers of tree species, numbers of individuals, wood volume, and Simpson diversity index values did not differ significantly between plots with spontaneous succession and reclaimed plots. The economic efficiencies of both types of plots were too burdened with high initial investments for levelling, which can theoretically be returned within 300 years for reclamation plots and 180 years for succession plots. According to our results and those of some other authors, values for diversity and wood production are similar or higher on plots resulting from spontaneous succession in comparison to values on reclaimed plots. For this reason, both types of management should be used to establish a new suitable mosaic of ecosystems in the post-mining landscape.
Keywords:
forestry reclamation; trees; plant diversity; production and economic perspectives
Available at various institutes of the ASCR
Comparison of forestry reclamation and spontaneous succession from plant diversity, production, and economic perspectives
The aim of our study was to determine whether the values of plant community diversity, the volume of wood, and the partial economic efficiency of plots left to spontaneous succession have yet reached ...
Testing a statistical forecasting model of electric energy consumption for two regions in the Czech Republic
Rajdl, Kamil; Farda, Aleš; Štěpánek, Petr; Zahradníček, Pavel
2015 - English
Precise forecasting of electric energy consumption is of great importance for the electric power industry. It helps system operators optimally schedule and control power systems, and even slight improvements in prediction accuracy might yield large savings or profits. For these reasons, many forecasting models based on various principles have been developed and studied. Because of energy consumption’s strong dependence on weather conditions, such models often utilize outputs from numerical weather prediction models. In this study, we present and analyse a statistical model for forecasting hourly electrical energy consumption by customers of E.ON Energie, a.s. in two regions of the Czech Republic. The aim of this model is to create hourly predictions up to several days in advance. The model uses hourly data of consumed energy from 2011–2014 and corresponding predictions of temperature and cloudiness provided by the ALADIN/ CZ model. The statistical model is based on a regression analysis applied to appropriate data samples and supplemented by several optional post-processing methods. Specifically, we use a robust linear regression algorithm to identify energy consumption’s dependence on temperature, the meteorological variable with the largest influence on consumption. Our post-processing methods focused on removing prediction bias resulting from economic situations (represented by the goss domestic product, GDP) and sudden temperature changes. We analysed the presented model from the point of view of the hourly predictions’ accuracy for 2013 and 2014. Accuracy was primarily measured by mean absolute error. It was evaluated for individual months, and the effects of individual parts of the model on accuracy value are shown. Introduction
Keywords:
forecasting model; electric energy; Czech Republic
Available at various institutes of the ASCR
Testing a statistical forecasting model of electric energy consumption for two regions in the Czech Republic
Precise forecasting of electric energy consumption is of great importance for the electric power industry. It helps system operators optimally schedule and control power systems, and even slight ...
Exploring beliefs about climate change and attitudes towards adaptation among Czech citizens
Lorencová, Eliška; Vačkář, David
2015 - English
Climate change currently represents one of the major global environmental problems. In order to respond to these changes, adaptation actions at all levels, from national to local, need to be undertaken (European Commission 2013). Moreover, perceptions of climate change are an important element affecting actual attitudes towards adaptation actions and influencing policy and communication regarding climate change (Lorenzoni et al. 2005). This paper presents the results of a survey on perceptions of climate change, including beliefs about climate change and attitudes towards adaptation, conducted among 1,024 Czech citizens in October 2014. Survey results show that the majority of respondents (78%) agreed with the statement that global climate change is happening. Positive responses about perceptions of climate change were found especially among younger people (18 to 34 years of age). In terms of adaptation measures, 51% of respondents had adopted a variety of individual actions (ranging from water savings to property insurance), discussed in the paper in further detail. Older people (≥ 45 years of age) with higher education preferred rather technical adaptation measures (e.g. flood protection for property, installation of rainwater reservoirs, etc.). The survey represents unique insights into attitudes towards climate change within the Czech Republic which had not previously been investigated to this extent. The results provided can support decision-making regarding adaptation policy, individual adaptation actions, and communication of climate change issues towards general public. Introduction
Keywords:
climate change; global environmental problems; Czech Republic
Available at various institutes of the ASCR
Exploring beliefs about climate change and attitudes towards adaptation among Czech citizens
Climate change currently represents one of the major global environmental problems. In order to respond to these changes, adaptation actions at all levels, from national to local, need to be ...
The effect of drought and nitrogen fertilization on the production, morphometry, and spectral characteristics of winter wheat
Trunda, Petr; Holub, Petr; Klem, Karel
2015 - English
Methods of study based on the spectral reflectance of vegetation are now commonly used in researching both natural ecosystems and field crops.The aims of this experiment were to evaluate the effect of drought and nitrogen (N) fertilization on N use efficiency in winter wheat and use the obtained spectral characteristics to assess stand heterogeneity as a potential consequence of different crop nutrition. Twelve experimental plots of winter wheat were manipulated to drought from 8 May 2013 to 12 June 2013. The effect of drought was observed in two treatments: control without fertilization (N0; 0 kg N ha−1) and N fertilization (N140; 140 kg N ha–1). Plant samples were then taken for determination of above-ground biomass and N content in dry matter. Spectral characteristics of wheat were measured in the earing phase at canopy level. The effect of drought on the morphometric parameters of winter wheat was statistically significant only on N-fertilized plots (N140). Total above-ground biomass decreased by a significant 18% in the N140 treatment as a result of the simulated drought. This decrease was reflected in statistically significant reductions of all individual plant parts (stems, leaves, spikes) in N140. Responses to drought stress were observed in many vegetation indices, particularly in NDVI, GNDVI, and WI/NDVI. The results show there are significant relationships between N content in the grain and vegetation indices. A quite marked separation was observed in the relationships between dry and ambient treatments for vegetation indices NRERI, TCARI/OSAVI, VOG2 and GM. Generally, the impact of drought increased at higher levels of N content in the grain, which corresponded with the results of morphometric analysis. Use of reflectance in the study of vegetation and field crops regarding risk assessment of mineral N leaching from soils has considerable potential especially in mapping large areas and monitoring temporal changes relating to N release.
Keywords:
field crops; natural ecosystem; winter wheat
Available at various institutes of the ASCR
The effect of drought and nitrogen fertilization on the production, morphometry, and spectral characteristics of winter wheat
Methods of study based on the spectral reflectance of vegetation are now commonly used in researching both natural ecosystems and field crops.The aims of this experiment were to evaluate the effect ...
The Bowen Ratio/Energy Balance method and detailed temperature profile measurements to improve data quality control
Pozníková, Gabriela; Fischer, Milan; Orság, Matěj; Trnka, Miroslav; Žalud, Zdeněk
2015 - English
Water plays a key role in the functionality and sustainability of ecosystems. In light of predicted climate change, research should focus on the water cycle and its individual components. The main component of water balance driving water from ecosystems is evapotranspiration (ET). One standard method for measuring ET is the Bowen Ratio/Energy Balance (BREB) method. It is based on the assumption that water vapour and heat are transported by identical eddies with equal efficiency. When using the BREB method, we assume that the profiles of temperature and air humidity are ideally logarithmic or at least consistent. Since the BREB method is usually based on measurements of temperature and humidity at only two heights, it is difficult to verify whether this assumption has been fulfilled. Potential profile inconsistencies are more likely for temperature because the sensible heat flux changes its sign more often and negative latent heat flux is not physically possible during positive sensible heat flux. We therefore conducted a field experiment using a 4-mhigh measurement mast with 20 thermocouples for detailed measurement of air temperature profiles above different covers, e.g. grassland, spring barley, and poplar plantations. Our main objective was to investigate the basic assumptions of the BREB method, i.e. the temperature profile’s consistency under various weather conditions. To be more specific, we aimed to investigate whether inflexion points occurred within the temperature profile and if so when.
Keywords:
temperature; Bowen ratio/energy balance method; data quality control
Available at various institutes of the ASCR
The Bowen Ratio/Energy Balance method and detailed temperature profile measurements to improve data quality control
Water plays a key role in the functionality and sustainability of ecosystems. In light of predicted climate change, research should focus on the water cycle and its individual components. The main ...
Automated eddy covariance data quality control for long-term measurements
Šigut, Ladislav; Mauder, M.; Sedlák, Pavel; Pavelka, Marian; Špunda, Vladimír
2015 - English
Estimation of matter and energy exchange using the eddy covariance method is often organized into regional or global networks. To achieve comparability among sites, it is important to standardize and specify the methodology used. Currently, quality control (QC) is one of the most time-demanding steps in data processing within the Czech Carbon Observation System. Although manual QC (MQC) enables consideration of more complex test applications, it is often difficult to document. The aim of this study was to establish an automated QC (AQC) scheme based on available literature and post-processing software and test its effectivity and reliability on sites comprising an agroecosystem and a mature European beech forest. AQC successfully flagged low-quality CO2 fluxes and provided estimates of net ecosystem productivity similar to estimates based on MQC. The tests’ efficiency was particularly high for the agroecosystem, where AQC removed 13% less data than did MQC. We conclude that the adopted AQC displays satisfactory performance, especially for sites with low canopy heights.
Keywords:
eddy covariance; data quality control
Available at various institutes of the ASCR
Automated eddy covariance data quality control for long-term measurements
Estimation of matter and energy exchange using the eddy covariance method is often organized into regional or global networks. To achieve comparability among sites, it is important to standardize and ...
NRGL provides central access to information on grey literature produced in the Czech Republic in the fields of science, research and education. You can find more information about grey literature and NRGL at service web
Send your suggestions and comments to nusl@techlib.cz
Provider
Other bases