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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
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.
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Analysis of poplar water-use efficiency at Domanínek experimental site
Hlaváčová, M. ; Fischer, Milan ; Tripathi, Abishek ; Orság, Matěj ; Trnka, Miroslav
The main objective of this study was to test if water-use efficiency (WUE) values are higher for short-rotation poplar coppice than they are for field crops. WUE of woody biomass was determined for 16 trees within a short-rotation poplar coppiced culture (poplar clone J-105) in the within the Czech Republic during the 2013 growing season. Total WUE of woody biomass for the 16 measured trees was 4.93 g kg−1 when calculated with the data set without a vapour pressure deficit condition and 4.63 g kg−1 when calculated with the data set with a vapour pressure deficit condition. Poplar clone J-105 is a tree species with relatively high WUE, but some crops or short-rotation coppice species can reach higher or comparable WUE values.
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Convergence of morphological, biochemical, and physiological traits of upper and lower canopy of European beech leaves and Norway spruce needles within altitudinal gradients
Rajsnerová, Petra ; Klem, Karel ; Večeřová, Kristýna ; Veselá, Barbora ; Surá, Kateřina ; Rajsner, Lukáš ; Holub, Petr ; Urban, Otmar
Climatic variation along altitudinal gradients provides an excellent natural experimental set-up for investigating the possible impacts of climate change on terrestrial organisms and ecosystems. The present work has explored for the first time the acclimation of upper versus lower canopy leaves or needles in European beech (Fagus sylvatica) and Norway spruce (Picea abies) forests along an altitudinal gradient. We tested the hypothesis that restrictive climatic conditions associated with high altitudes reduce within-canopy variations of leaf traits. The investigated beech and spruce forests were located on the southern slope of the Hrubý Jeseník Mountains (Czech Republic). All measurements were taken on leaves from the upper and lower parts of the canopy of mature trees (>60 years old) growing at low (400 m a.s.l.), middle (720 m a.s.l.), and high (1,100 m a.s.l.) altitudes. Generally, we observed that with increasing altitude, which is associated with adverse microclimatic conditions, a convergence of CO2 assimilation rate and other physiological, morphological, and biochemical characteristics between the upper and lower canopy occurred. However, differences in altitudinal response among individual traits and species were found. Such plasticity in acclimation of leaves and needles has the potential to cause substantial change in the photosynthesis of individual parts of forest canopies within the vertical profile and their contribution to the overall carbon balance of vegetation.
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The relationships of soil CO2 flux with selected Norway spruce root parameters and sterol content in the soil
Holub, Filip ; Fabiánek, Tomáš ; Večeřová, Kristýna ; Moos, Martin ; Oravec, Michal ; Tříska, Jan ; Marková, I. ; Edwards, Magda ; Cudlín, Pavel
The flow of CO2 from the soil is a very important part of the carbon cycle in an ecosystem. The aim of our work was to determine how roots and rhizospheric fungi contribute to CO2 flux from the soil. Preliminary results from two years of research are presented. The research on how root biomass as well as ergosterol and phytosterol contents in roots and soil affected CO2 flux from the soil was conducted in a 108-year-old Norway spruce (Picea abies (L.) Karst.) forest in the Drahany Highlands during 2010 and 2011. CO2 flow was measured using a LI-8100 portable closed gasometric system (Li-Cor, USA). The dry weight and volume of individual root categories (< 1 mm, 1–2 mm, 2–5 mm, > 5 mm), C and N contents in the roots, as well as ergosterol, β-sitosterol, and campesterol contents in the soil and roots were determined from root-containing soil samples located in the circular measurement chamber. In addition, sterol content was determined in the soil only. Our soil respiration results correspond with the findings of Buchman (2000) who found respiration values between 5–7 μmol CO2 m−2 s−1 in a 111-year-old spruce forest. A significant influence on soil respiration was proven only for sitosterol content in the soil. The relationships among soil CO2 flux, root characteristics, and nitrogen and sterol contents in the roots and soil are discussed.
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Summer fluxes of nitrous oxide from boreal forest
Macháčová, Kateřina ; Pihlatie, M. ; Halmeenmäki, E. ; Pavelka, Marian ; Dušek, Jiří ; Bäck, J. ; Urban, Otmar
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.
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Využití shlukové analýzy k vyhodnocní půlroční měřící kampaně elementární plynné rtuti z atmosférické stanice Křešín u Pacova
Veselik, P. ; Dvorská, Alice
Příspěvek se zabývá vyhodnocením pozaďových hodnot plynné elementární rtuti v ovzduší z Atmosférické stanice Křešín u Pacova. Měření byla prováděna v 10 minutových časových intervalech za období od prosince 2012 do června 2013 dvěma identickými analyzátory umístěnými vedle sebe v přízemním kontejneru. Tato dlouhodobá měřící kampaň byla rozdělena do přibližně týdenních časových intervalů. Cílem příspěvku je ukázat použití shlukové analýzy k nalezení takových časových období, kdy si podle vybraných kritérií dvojice měření nejvíce odpovídají. Klasifikace byla provedena pomocí shlukové analýzy regresních koeficientů získaných při modelování týdenních měření druhým přístrojem v závislosti na měření prvním přístrojem. Z provedené analýzy vyplývá existence pěti období, ve kterých se regresní přímky příliš neliší. Jejich analýze je věnována další pozornost.
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Aplikace růstových modelů pro lokální hodnocení dopadů změny klimatu na vybrané plodiny
Hlavinka, Petr ; Trnka, Miroslav ; Balek, Jan ; Dubrovský, Martin ; Pohanková, Eva ; Žalud, Zdeněk
Metodika je zaměřena na přehledný popis problematiky využití specializovaných softwarových nástrojů nazývaných růstové modely s důrazem na jejich aplikaci pro hodnocení dopadů změny klimatu na lokální úrovni. Ambicí této publikace je seznámit čtenáře se stručnou historií vývoje růstových modelů, jejich členěním, aktuálními trendy jejich vývoje a využití, ale v první řadě prezentovat metody přípravy vstupních databází, prvotního nastavení modelů, kalibraci jejich parametrů, přes ověření spolehlivosti prostřednictvím nezávislého vzorku dat (validace), propojení se scénáři očekávaného vývoje klimatu v budoucnu až po hodnocení dopadů změny podmínek na významné polní plodiny a vybrané reprezentativní lokality v České republice.
Plný tet: Metodika_rustove_modely_2015 -  PDF
Plný text: content.csg - PDF
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Právo na informace jako základní lidské právo
Kolman, Jiří
Při analýze otázky práva na informace u institucí EU je potřeba si vyjasnit fundamentální teoreticko-právní otázku, jestli lze toto právo považovat za základní lidské právo uplatnitelné mj. i v právu mezinárodním. V současnosti EU lavíruje mezi supranacionálním přístupem a pohledem intergovernmentálním, který se projevuje aplikací pravidel světa diplomacie (tj. mezinárodního práva). Existuje v případě unijních institucí prostor pro plnohodnotný přístup k informacím, tak jak jsme zvyklí z většiny členských zemí?
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Attribution of European temperature variability during 1882–2010: A statistical perspective
Mikšovský, Jiří ; Pišoft, P.
Gridded monthly temperature data (GISTEMP and Berkeley Earth) covering the European region were investigated for the presence of components attributable to climate forcings, both anthropogenic and natural, and to major modes of internal climate variability. Effects of individual predictors were separated by multiple linear regression applied to time series over 1882–2010. It was shown that the presence of a warming trend correlated with greenhouse gases concentration was generally strong in European temperatures and typically combined with mild cooling ascribable to anthropogenic aerosols. Components attributable to variations in solar activity were rather weak and not statistically significant in most locations, as were the imprints of large volcanic eruptions. A strong association between North Atlantic Oscillation phase and temperature was confirmed for much of Europe, while temperature oscillations synchronized with the El Niño Southern Oscillation were quite limited in magnitude and displayed low levels of statistical significance. The influence of the Atlantic Multidecadal Oscillation was noticeable particularly in the western-most parts of Europe, whereas the Pacific Decadal Oscillation’s significant impact extended to Scandinavia.
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