National Repository of Grey Literature 96 records found  beginprevious84 - 93next  jump to record: Search took 0.03 seconds. 
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.
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.
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.
The use of cluster analysis to evaluation half-year measurement campaign of gaseous elemental mercury from atmospheric station Křešín u Pacova
Veselik, P. ; Dvorská, Alice
This paper deals with evaluation of gaseous elemental mercury in the air from Atmospheric Station Křešín u Pacova. The measurements were conducted with two identical instruments positioned right next to each other in one ground-based container in a 10 min time step, between December 2012 and June 2013. This measurement campaign was aggregated into approximately weekly intervals. The aim of this paper is to show the use of cluster analysis for finding those time periods which correspond the most according to appropriately selected criteria. Classification was performed by using cluster analysis of regression coefficients obtained by modelling weekly measurements by the second device on the measurements from the first device. Results of this analysis indicate the existence of five periods in which the regression lines show certain similarities. Further attention is paid to their analysis.
Application of growth models for local assessment of the impact of climate change on selected crops
Hlavinka, Petr ; Trnka, Miroslav ; Balek, Jan ; Dubrovský, Martin ; Pohanková, Eva ; Žalud, Zdeněk
This publication is focused on the description of specialized software named as crop growth models and its using emphasizing the application for climate change impact assessment at local scale. The ambition of this publication is to introduce brief history of the crop growth models development, its classification, actual trends of their progress and applications and last but not least, present procedure leading to the preparation of the input datasets, the initial setup, parameters calibration, validation through set of independent datasets and consequently the implementation of climate change scenarios for assessment of possible impact of future conditions on selected important field crops and set of representative sites in the Czech Republic.
Fulltext: content.csg - Download fulltextPDF
Plný tet: Metodika_rustove_modely_2015 - Download fulltextPDF
Orchids of Nepal: phytogeography and economic importance
Timsina, Binu ; Rokaya, Maan Bahadur ; Kindlmann, Pavel ; Munzbergová, Z.
In total, 118 orchid species (25%) are endemic to the Himalayan region and 21 species are endemic to Nepal. Krober’s percentage similarity showed that the EAFR and ICFR have the highest percentage similarity (87%) followed by the MFR and ICFR (62%). In total, 92 species were used for medicinal purposes and 6 as food plants in Nepal. We conclude that Nepal is rich in orchid flora and the highest percentage of orchids originates from the EAFR.
The right to information as a fundamental human right
Kolman, Jiří
When analysing free access to information of the EU institutions it is needed to clarify the fundamental theoretical question of law, if that law can be considered as a basic human right exercisable, inter alia, in international law application. Currently EU law oscillates between supranational approach and intergovernmental point of view using diplomacy rules (international law). Is there, in the case of the EU institutions, space for full access to information, as we are used to it in the case of the EU member states?
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.
Flux footprints in different ecosystems
Macálková, Lenka ; Havránková, Kateřina ; Pavelka, Marian
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.
Creation of wind rosettes using the CALMET model
Škáchová, H. ; Vlček, O. ; Trusina, Jan
The CALMETT model is a part of dispersion modeling system (CALPUFF), which is a diagnostical modul for flow fields that counts vertically divided fields of wind direction and wind speed. The model is able to calculate micrometeorological characteristics of the boundary layer above the Earth´s and water surface. To verify the model, test calculations were made at two professional stations CHMI (Praha – Libuš, Mošnov) for the period of 2008 – 2012. Košetice Observatory was chosen for comparison of the stability divided and total height rosettes. The results showed that the CALMETT model is a suitable tool for creating stability divided wind rosettes. When calculating wind rosettes, the correct settings and representativeness of input data should be born in mind.

National Repository of Grey Literature : 96 records found   beginprevious84 - 93next  jump to record:
Interested in being notified about new results for this query?
Subscribe to the RSS feed.