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How will a longer vegetative season affect carbon sequestration in plant biomass
Kasperová, Denisa ; Albrechtová, Jana (advisor) ; Ponert, Jan (referee)
As a result of human activity, a large number of greenhouse gases, especially CO2, is released into the atmosphere, which causes a greater greenhouse effect and an increase in the temperature of the surface of the planet and the air in the atmosphere. Ongoing climate change is one of the great challenges facing society, as rising temperatures on the planet greatly affect the functioning of its ecosystems. Extremes arising from climate change, especially temperature rise and lack of precipitation or a change in the annual distribution of precipitation, affect the physiology and phenology of plants. Higher temperatures cause plant growing seasons to shift and lengthen, which has a direct impact on the sequestration of carbon in plant biomass through a biochemical, physiological plant process called photosynthesis. The increase in CO2 concentration in the atmosphere is slowed down by terrestrial forest ecosystems, as they can retain carbon in their tissues, especially in wood, for a relatively long time before it returns to the atmosphere. However, the efficiency of binding carbon into biomass also depends on other physiological processes, e.g., photorespiration, breathing, gas exchange between the plant and the atmosphere. Stressors caused by climate change can then limit growth, photosynthesis,...
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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...
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Microbial communities and carbon cycling in subglacial ecosystems and their analogues
Rybár, Marek ; Stibal, Marek (advisor) ; Řeháková, Klára (referee)
Subglacial environments are located at the interface of glacier ice and bedrock. They represent one of the major ecosystems associated with glaciers and ice sheets. They contain liquid water and fine material including organic matter, accumulated during periods of glacier advance. It is well established that there are active microbial communities residing in these environments, which are adapted to living in extreme conditions. Subglacial ecosystems are mostly isolated from the atmosphere and thus their oxygen content is usually very low. Therefore, the organisms residing in these environments often employ anaerobic/anoxic strategies to ensure their survival. However, knowledge of these communities is limited due to practical constrains associated with subglacial ecology and biogeochemistry research. The activity of microorganisms beneath glaciers significantly influences carbon cycling. In recent years, this ecosystem is dynamically changing and may have important impact on regional and global carbon cycle. Therefore, it is important to better understand this ecosystem. This thesis summarizes recent knowledge of microbial communities and carbon cycling in this ecosystem and discusses suitable analogues, which could help us understand the fascinating subglacial ecosystem and formulate future research...
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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...
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Decomposition of aboveground biomass of a herbaceous wetland stand
KLIMOVIČOVÁ, Lucie
The master?s thesis is part of the project GA ČR č. P504/11/1151- Role of plants in the greenhouse gas budget of a sedge fen. This thesis deals with the decomposition of aboveground vegetation in a herbaceous wetland. The decomposition rate was established on the flooded part of the Wet Meadows near Třeboň. The rate of the decomposition processes was evaluated using the litter-bag method. Mesh bags filled with dry plant matter were located in the vicinity of the automatic meteorological station at four randomly selected sites. Values of the decomposition rate were assessed in two experiments. In the first experiment the litter bags were fixed in April 2009. The litter bags were fixed in the vertical position and they had one size. Values of the decomposition rate were assessed for 6 sampling dates and the total exposure time was 2,5 years. The decrease of the total dry mass was 18,37 % in the first year and 13,05 % in the second year. The value of LDR was 0,7227 in the first year and 0,4740 in the second year. In the 2nd experiment the litter bags were fixed in November 2010. The litter bags were fixed in the vertical and horizontal position, respectively, and they were of two sizes (small, big). Values of the decomposition rate were assessed for 2 sampling dates and the total exposure time was one year. The total annual value of LDR was 0,5212 for the vertical bags and 1,0676 for horizontal bags.
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