Ne (220)
Použitá omezení
(4)
Počet nalezených dokumentů:
220
Publikováno od
do
The effect of drought and nitrogen fertilization on the production, morphometry, and spectral characteristics of winter wheat
Trunda, Petr; Holub, Petr; Klem, Karel
2015 - anglický
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.
Klíčová slova:
field crops; natural ecosystem; winter wheat
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 - anglický
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.
Klíčová slova:
temperature; Bowen ratio/energy balance method; data quality control
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 - anglický
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.
Klíčová slova:
eddy covariance; data quality control
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
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 ...
Köppen–Geiger climate classification by different regional climate models according to the SRES A1B scenario in the 21st century
Szabó-Takács, Beáta; Farda, Aleš; Zahradníček, Pavel; Štěpánek, Petr
2015 - anglický
We investigate future climate conditions projected by six regional climate model (RCM) simulations driven by the SRES A1B emission scenario. As a diagnostic tool of climate change, we used the Köppen–Geiger climate classification as it is suitable for assessing climate change impacts on ecosystems. The analysis is based on a comparison of Köppen–Geiger climate subtypes during two future time slices (2021–2050 and 2070– 2100) with climate subtypes observed during 1961–2000. All RCMs showed expansion of the area covered by warmer climate types in the future, but the magnitude of the growth varied among RCMs. The differences stemmed from several sources, mainly boundary forcing provided by the driving global circulation models (GCMs) as well as different physical packages, resolution, and natural variability representation in individual GCMs. In general, RCMs driven by the ECHAM5-r3 GCM projected cooler climate conditions than did RCMs driven by the ARPÈGE GCM. This can be explained by two factors related to ECHAM5-r3: i) exaggerated transport of cool and moist air from the North Atlantic to Europe in summer, and ii) winter advection of cold air from the Artic owing to North Atlantic Oscillation blocking pattern alteration during solar minima as well as higher natural variability. RCM-related properties, such as physical package and spatial resolution, may also significantly affect climate predictions, although they do so to a smaller extent than does the driving GCM data.
Klíčová slova:
climate models; climate classification; 21st century
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Köppen–Geiger climate classification by different regional climate models according to the SRES A1B scenario in the 21st century
We investigate future climate conditions projected by six regional climate model (RCM) simulations driven by the SRES A1B emission scenario. As a diagnostic tool of climate change, we used the ...
Long-term productivity of short rotation coppice under decreased soil water availability
Orság, Matěj; Fischer, Milan; Tripathi, Abishek; Žalud, Zdeněk; Trnka, Miroslav
2015 - anglický
Wood, in fact, is the unsung hero of the technological revolution that has brought us from a stone and bone culture to our present age (Perlin 1991). Given its high-energy content and versatile use, biomass in the form of wood has been used for energy purposes for millennia. The production and use of woody biomass resources has been expanding around the world. The main drivers of its use as a source of energy are diversification and mitigation of energy related greenhouse gas emissions through partial substitution for fossil fuels. An alternative to sourcing wood biomass from natural forests is short rotation woody coppice. Its productivity is largely dependent on the environment in terms of climatic conditions. Especially drought is the main constraint on woody biomass production and involves serious economic consequences. For that reason, our field experiment was designed to evaluate the impact of decreased soil water availability on productivity of a poplar based short rotation coppice plantation over multiple growing seasons during 2011–2014. Aboveground biomass productivity of treatments with and without throughfall exclusion was assessed within this study. Our results show a systematic decline in the productivity of the plots subjected to decreased soil water availability by 30% in 2011, 20% in 2012, 49% in 2013, and 51% in 2014 compared to control plot. Aboveground biomass productivity ranged from 8.8 to 9.9 t dry matter ha−1 year−1 for the control treatment and 4.5 to 8.0 t dry matter ha−1 year−1 for the treatment with throughfall exclusion.On average, the throughfall exclusion treatment exhibited 47% less productivity than control treatment had over the entire study period.
Klíčová slova:
short rotation coppice; soil water availability
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Long-term productivity of short rotation coppice under decreased soil water availability
Wood, in fact, is the unsung hero of the technological revolution that has brought us from a stone and bone culture to our present age (Perlin 1991). Given its high-energy content and versatile use, ...
The influence of reduced precipitation supply on spring barley yields and the ability of crop growth models to simulate drought stress
Pohanková, Eva; Orság, Matěj; Hlavinka, Petr
2015 - anglický
This paper evaluates the first year (2014) of results from a field experiment with spring barley (cultivar Bojos) under reduced precipitation supply. The field experiment was carried out at an experimental station in the Czech Republic and consisted of small plots in two variants and three repetitions. The first variant was uncovered, and the second was partly covered to exclude rain throughout the entire vegetation season. For plots’ partial covering, a material was used to divert rainwater away from 70% of the plots. The main aim was to determine whether there are any differences in soil water content or in grain yield size between uncovered and partly covered plots and to compare the results obtained. Data measured in this field experiment were used to compare simulations of this field experiment in the DAISY crop growth model. Subsequently, the crop growth model’s ability to simulate grain yield, which was affected by drought stress, was explored. In reality, differences in phenological development and grain yield size were not evident. Reducing precipitation supply in DAISY by about 70% led to simulations of covered plots with reduced grain yield in accordance with the initial hypothesis. Agreement between observed and simulated grain yield was evaluated using selected statistical indicators: root mean square error (RMSE) as a parameter of average magnitude of error and mean bias error (MBE) as an indicator of systematic error. RMSE of grain yield was 2.6 t ha−1. MBE revealed grain yield undervalued by 2.6 t ha−1.
Klíčová slova:
spring barley; crop growth models; simulate drought stress
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
The influence of reduced precipitation supply on spring barley yields and the ability of crop growth models to simulate drought stress
This paper evaluates the first year (2014) of results from a field experiment with spring barley (cultivar Bojos) under reduced precipitation supply. The field experiment was carried out at an ...
Effects of vegetation season and needles’ position in spruce canopy on emissions of volatile organic compounds
Večeřová, Kristýna; Holišová, Petra; Pallozi, E.; Guidolotti, G.; Calfapietra, Carlo; Urban, Otmar
2015 - anglický
The main objective of this study was to investigate seasonal changes and vertical distribution in emissions of biogenic volatile organic compounds (BVOCs) within a Norway spruce canopy profile. Emissions were measured on current-year needles from the upper and lower canopy in early July and late August. Our results show that total BVOC emissions under standardized conditions (light intensity 1,000 µmol m–2 s–1, temperature 30°C) are higher in July than they are in August. BVOC emissions from upper canopy needles were approximately 3 times higher than were those from lower canopy needles. This difference was observed in July but not in August. The monoterpenes α-pinene, camphene, and terpinolene showed the most significant differences between emissions from upper and lower canopy needles.
Klíčová slova:
vegetation season; spruce canopy; organic compounds
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Effects of vegetation season and needles’ position in spruce canopy on emissions of volatile organic compounds
The main objective of this study was to investigate seasonal changes and vertical distribution in emissions of biogenic volatile organic compounds (BVOCs) within a Norway spruce canopy profile. ...
The importance of hydromorphological analysis in evaluating floodplain disturbances – an upper Stropnice River case study
Jakubínský, Jiří; Pelíšek, I.; Cudlín, Pavel
2015 - anglický
This contribution deals with a comparative analysis of the hydromorphological state of a river network and the ecological status of a neighbouring floodplain area. The issue has gained great importance especially in addressing the causes and effects of flood events, which are an increasingly frequent manifestation of global environmental change at the local level. The area of interest was the upper part of the Stropnice River basin in Southern Bohemia with an area of about 100 km2. The basin is characterized by wide variability of natural conditions and human activities. The main objective was to analyse how the river’s morphological status affects habitat type naturalness. We endeavoured to determine the extent to which hydromorphological modifications contributed to transforming riparian natural habitats into more human-influenced habitats. Based on the results, we can conclude that within the area of interest the direct link between rivers and their close surroundings was only minimal. A significant role in shaping this relationship was played by a large anthropogenic modification of the entire floodplain area as well as the actual riverbed, which often causes completely different results. In areas where the floodplain ecosystem displayed relatively favourable environmental values, the relevant channel reach was degraded significantly, and vice versa. These facts point to longterm effects from anthropogenic pressure, which are manifested in the mutually and not well coordinated management of the river network and land-use system within the watershed.
Klíčová slova:
hydromorphological analysis; Stropnice River; floodplain disturbances
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
The importance of hydromorphological analysis in evaluating floodplain disturbances – an upper Stropnice River case study
This contribution deals with a comparative analysis of the hydromorphological state of a river network and the ecological status of a neighbouring floodplain area. The issue has gained great ...
Estimating values of urban ecosystem services in Kladno
Frélichová, Jana; Pártl, Adam; Harmáčková, Veronika Zuzana; Vačkář, David
2015 - anglický
The benefits provided by urban nature have a substantial capacity to enhance human well-being. We quantify these benefits in the city of Kladno through the concept of ecosystem services by combining a value transfer method with surveys on citizen satisfaction and ecosystem services recognition. The results provide biophysical values of carbon sequestration and run-off and reveal stronger perception of benefits and higher preferences among citizens of Kladno for recreational services. Therefore, recreation is more suitable as a flagship service to encourage public participation than are such expert indicators as tonnes of carbon sequestered and increased run-off.
Klíčová slova:
Urban ecosystem services; Kladno; carbon sequestered
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Estimating values of urban ecosystem services in Kladno
The benefits provided by urban nature have a substantial capacity to enhance human well-being. We quantify these benefits in the city of Kladno through the concept of ecosystem services by combining ...
Interactive effects of elevated CO2 concentration, drought, and nitrogen nutrition on yield and grain quality of spring barley and winter wheat
Surá, Kateřina; Rajsnerová, Petra; Veselá, Barbora; Klem, Karel
2015 - anglický
The interactive effects of elevated CO2 concentration (EC; 700 μmol mol–1), drought stress, UV exclusion, and nitrogen nutrition were studied in open-top chambers located in the Bohemian–Moravian highlands (24 in total). Above-ground biomass at the time of harvest, grain yield, and grain quality parameters were studied in winter wheat (variety Bohemia) and spring barley (variety Bojos). The results showed that elevation of CO2 concentrations increased above-ground biomass and grain yield. Higher levels of nitrogen increased the stimulatory effect of EC on above-ground biomass and grain yield. In addition, UV exclusion stimulated the effect of EC. EC generally led to increased rates of photosynthesis and assimilate formation. Increased storage of starch in the grain led to an unbalanced proportion of proteins and a decrease in their relative content in grain. Similarly to grain yield and above-ground biomass, the decrease in protein content under EC was also more pronounced under UV exclusion. EC led also to reduction of other quality parameters, such as the Zeleny sedimentation test. This effect is more pronounced when nitrogen is not a limiting factor as well as under the effect of drought. The stronger effect under drought stress is probably due to increased water use efficiency.
Klíčová slova:
CO2 concentration; nitrogen nutrition; grain quality; winter wheat
Plné texty jsou dostupné na jednotlivých ústavech Akademie věd ČR.
Interactive effects of elevated CO2 concentration, drought, and nitrogen nutrition on yield and grain quality of spring barley and winter wheat
The interactive effects of elevated CO2 concentration (EC; 700 μmol mol–1), drought stress, UV exclusion, and nitrogen nutrition were studied in open-top chambers located in the Bohemian–Moravian ...
NUŠL poskytuje centrální přístup k informacím o šedé literatuře vznikající v ČR v oblastech vědy, výzkumu a vzdělávání. Více informací o šedé literatuře a NUŠL najdete na webu služby.
Vaše náměty a připomínky posílejte na email nusl@techlib.cz
Provozovatel
Zahraniční báze