National Repository of Grey Literature 394 records found  beginprevious251 - 260nextend  jump to record: Search took 0.01 seconds. 
Palaeocology of plant-arthropod associations from the Lower Miocene of the Most Basin in northern Bohemia (Czech Republic)
Knor, Stanislav
Terrestrial plants and insects account for the majority of the Earth's biodiversity today, and almost half of all insect species are herbivores. Thus, insects and plants share ancient associations date back for more than 400 million years. However, investigation of their interactions stands largely at the beginning in Western Europe. Nearly 4300 plant remains showing various kinds of feeding damages are available for the present study. These trace fossils are classified as so-called functional feeding-groups supply an outstanding example of the complexity, the structure and the changes of terrestrial ecosystems, are not well known during this interval. In Europe, the Neogene is characterized by palaeogeographic re- organization due to the collision of the African with the Eurasian plates. The Neogene plant record in Europe is rich and diverse offering a profound large-scale understanding of the floristic and vegetational development. A database of fossil traces from the Most Basin was compiled and analyzed by various statistical methods in terms of the diversity and intensity of palaeo-herbivory. The primary objective is to present results on the development of insect herbivory through the section of the Bílina Mine in North Bohemia, with the aim of understanding principal factors that caused the...
Assessment of climate change impacts on selected ecosystem services in the Czech Republic: application of land use scenarios
Lorencová, Eliška ; Vačkářová, Davina Elena (advisor) ; Müller, Karel (referee) ; Cudlín, Pavel (referee)
Doctoral thesis abstract Assessment of climate change impacts on selected ecosystem services in the Czech Republic: Application of land use scenarios MSc Eliška Lorencová Climate and land use change are recognized as the greatest global environmental problems. Both considerably impact delivery of crucial ecosystem services, such as carbon sequestration, water flow regulation, erosion control, and food and fibre production. By combining future projections of ALARM scenarios (for years 2020, 2050 and 2080) with modelling of ecosystem services, the study aims to evaluate climate change impact on selected ecosystem services (carbon storage and sequestration, erosion control and sediment retention) in the Czech Republic. This study provides quantitative as well as spatially explicit analysis of the impacts on selected ecosystem services in the Czech Republic. Performed ecosystem service assessment indicates that spatial distribution of provision of ecosystem services, such as carbon storage and sequestration, sediment retention reflects the projected future land use changes. In case of carbon sequestration, SEDG scenario shows the lowest carbon sequestration rates accounting for 37,029.6 Gg C within the period 2000-2080. Stable vegetation cover is one of the factors that play important role in amount of sediment...
Závislost predace a rychlosti metabolismu na teplotě z pohledu kořisti i predátora
MODRÁ, Denisa
Climate changes affect species interactions which can have cascading effect up to the ecosystem level. This work investigates the effects of temperature and predator size on predator prey interactions by measuring the feeding rates of predators and metabolic rates of both predator and prey, using dragonfly larvae Aeshna cyanea and toad tadpoles Bufo bufo as a model system. Possible consequences of the findings for the impacts of climate change and predation on amphibian populations are discussed.
Frost Indexes for the Cold Half-year in the Czech Republic
Zahradníček, Pavel ; Rožnovský, J. ; Brzezina, J. ; Štěpánek, Petr ; Farda, Aleš ; Chuchma, F. ; Potopová, V.
The dynamics of air temperatures during cold half-year to a large extent affect all human activities. Most significant damages are caused by minimum air temperatures dropping to very low values. Due to the current ongoing climate change, air temperatures in winter in general are increasing, however, this does not necessarily mean the frequency of these very low temperatures decreases. It is not easy to express the course of air temperatures during cold periods using some simple characteristic. Meteorologists and climatologists use various characteristics, which can be referred to as frost indexes. These include the number of frost, ice or arctic days. Since these indexes not always perfectly reflect reaction of the nature to a particular temperature threshold, the analysis also included number of days with minimum air temperature below -3, -5, -7, -10, -15, -20 and -25°C. In the last 15 years (2001-2015), there has been a decrease in the frost indexes in comparison to the normal period 1961-1990, this trend however, is not always statistically significant. Significant changes were found in particular in case of the number of days with a higher temperature threshold (frost, ice days and minimum air temperature above -3 to -10°C). In contrast, days with extremely low temperatures are relatively rare (sometimes only observed once in several years), so the dominant factor here is rather variability. The paper also includes an analysis of possible future development based on the most recent climatological models.
Carbon sequestration by forest ecosystems in canging climate.
Hlaváčková, Lucie ; Lhotáková, Zuzana (advisor) ; Urban, Otmar (referee)
The global carbon cycle is in the focus of the scientists' interest, because understanding carbon sinks and their relationships can show the solutions of problems related with increasing CO2 concentration in the atmosphere in the future. I focused on the role of forests ecosystems in this carbon cycle. All forests cover almost one third of the Earth's land area. By photosynthesis they bind big part of atmospheric carbon to their biomass. Sink strength of forest can differ according to the type of biome, forest stand age and actual climatic conditions. Forest biomes can be generally divided according to the latitude to three groups: tropical forest biomes, temperate forests and boreal forests. The size of carbon stock decreases in this order. Other parameters, such as net primary production and respiration differ in dependence on the particular ecosystem. Tropical rain forests represent great carbon stock, but their deforestation causes massive C emissions back to the atmosphere. Boreal forests aren't considered as important carbon sink, but they influence local climate. Some speculations can also appear about the old forests. It is possible to find authors, who claims, that old forests are no more carbon sinks, so that their carbon balance is neutral. Many surveys prove that they bind less carbon...
Regional Climate Modeling
Belda, Michal ; Halenka, Tomáš (advisor) ; Huth, Radan (referee) ; Metelka, Ladislav (referee)
Regional climate models are commonly used for downscaling global climate simulations to the regional scale using nested limited-area models. One of the main goals of this work was the application of regional model RegCM in very high resolution for the region with complex topography in the framework of EC FP6 project CECILIA. RegCM was employed to downscale climate change scenario simulations performed by ECHAM5 model according to the IPCC A1B emission scenario for Central and Eastern Europe in 10km resolution. Validation of model performance, assessed by nesting RegCM in ERA-40 reanalysis, shows improvement of regional climate patterns mainly in mountainous areas. Temperature is well represented with mostly cold bias around -1 žC. Precipitation is affected by large biases around 80 %, in mountainous areas up to 400 % overestimation in winter. Downscaled climate change signal shows average warming 0.5­1.5 žC in period 2021­2050 and 2­4 žC in period 2071­2100. Precipitation changes are mostly within ±0.5 mm/day. RegCM3­beta version with adjusted precipitation scheme parameters shows improvement of the precipitation bias, difference in climate change is rather negligible. Experiments with different convection schemes of RegCM in a case study for Africa performed in the framework of CORDEX project are...
Analysis of the temperature series of meteorological observatory Milešovka (1905 - 2010)
Lhotka, Ondřej ; Sládek, Ivan (advisor) ; Štekl, Josef (referee)
From the climatological aspect, the meteorological observatory Milešovka is one of the most important stations at Czech Republic. When this master's thesis was writen, the 106 years long set of the daily mean air temperature was available. This dataset is not influenced by the urban heat island. Beside the older studies, the trend of the mean annual air temperature increased on 1,02řC/100 years. The highest value is in the spring, the lowest one in the winter. The value of mean diurnal temperature range is increasing. The duration of the frost period is decreasing, on the contrary, the lenght of the growing season is prolonging. 36 % of the absolute extremes of maximal daily temperature were detected in the period 1996-2010. On the other hand, the absolute extremes of minimal daily temperature are rare in this period. The sub-seasonal anomalies are three or more days long significant deviations from the smoothed annual progress of the air temperature. This anomalies of the air temperature has highest mean value of deviations and longest mean duration in winter. The relations between the sub-seasonal anomalies and the meteorological singularities are weak.
Winter teritoriality im passerines in relation to environmental and climatic conditions
Glückseligová, Pavla ; Musil, Petr (advisor) ; Reif, Jiří (referee)
This thesis is focused on winter territoriality of passerines. It summarizes general knowledge of territories, territorial behaviour and broader knowledge about winter territoriality. Winter social behaviour of individual species, their territoriality, migratory strategy and food preferences were summarized for Western Palearctic bird species. Furthermore, effect of climate change on passerines and their migratory behaviour, timing of breeding and their relationship to food abundance and conspecific competition. In the last chapter, there is discussed effect of climate change on species displaying wintering territoriality. Increasing temperature can affect food availability, competition for sources and consequently reproduction success.
Freshwater wetlands as a biogeochemical archive: Temporal changes in climate and environmental records
Zemanová, Leona ; Novák, Martin (advisor) ; Mihaljevič, Martin (referee) ; Hojdová, Marie (referee)
Worldwide, peatlands cover an area of 4.106 km2 . Plant primary production dominated over organic matter decomposition and enabled organic matter to accumulate during the last 11 000 years. Peatlands represent a reservoir of atmospheric carbon and they are a useful scientific tool for reconstructions of historical atmospheric pollution. The first part of the thesis focuses on peatlands as a dynamic carbon reservoir under predicted climate change that would influence carbon cycling and emissions of greenhouse gases into the atmosphere. Three methodological approaches were used - a mesocosm laboratory incubation, a transplant experiment and in situ gas flux measurements. The laboratory incubation studied the response of peat samples from temperate (Velké Dářko, Czech Republic) and boreal (Stor Åmyran, Sweden) zone to a temperature increase, water table decrease and their combination. Today, the warmer site exhibits ~14 times higher CH4 production potential than the colder site (28 mg m-2 hr-1 at VD, and 2 mg m-2 hr-1 at SA). Both sites respond differently to temperature increases. Changes in methane production were up to 9 fold due to different temperatures. A gradual decrease of water table level from 2 to 14 cm below the peat surface had a much stronger effect, VD exhibited a decrease in methane...
Role of aerosol in climate change
Švátora, Milan ; Hůnová, Iva (advisor) ; Hovorka, Jan (referee)
Atmospheric aerosol is a suspension of liquid or solid particles or their mixture in the atmosphere. Tropospheric aerosols can get into the air from its natural sources or from anthropogenic sources. Release of carbon dioxide from burning fossil fuels and organic and elemental carbon from biomass burning are the major anthropogenic sources of aerosols. Primary aerosols have a direct source of emissions (dust from quarries or from land, sea salt particles in the waves, volcanic ash during volcanic eruptions). Secondary aerosols are formed by chemical reactions of substances in the atmosphere, which converts the gas particles - so- called conversion of gases to particles (formation of nitrates by oxidation of nitrogen oxides and sulfates from sulfur dioxide). Atmospheric aerosol is an important component of the atmosphere and contributes to significant atmospheric events, such as precipitation formation and precipation fall, radiation balance of Earth. Aerosols can affect the radiation balance of the Earth in two ways. First, through absorption and scattering of shortwave and long wave radiation - so-called direct effect. Or serve as condensation nuclei on which water is condenses. Aerosols can affect formation, quantity, length of existence and radiation properties of clouds - so-called indirect effect. In...

National Repository of Grey Literature : 394 records found   beginprevious251 - 260nextend  jump to record:
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