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The effect of pathogens on invasive plants
Sládečková, Julie ; Koubek, Tomáš (advisor) ; Čuda, Jan (referee)
Invasive plants can destroy entire ecosystems, reduce biodiversity and thus threaten the environment. Number of invasive species is increasing and so their negative impact on the environment. Various reasons can be behind the emergence of invasions, one of them is, for example, escaping from natural enemies. This can make the plant more competitive, have greater reproductive potential and spread better. However, if natural enemies are added to the new area, the number of invasive plants can be regulated. This is the principle of biocontrol, which is a method used to reducing the magnitude of invasions and their consequences. This method has almost no negative impacts on the environment, unlike chemical and mechanical methods of plant removal. Biocontrol has a long-term effect and therefore is also cheaper. However, when biocontrol is used, there is a certain risk that non-target plant species will be affected or that it will not be effective enough. Pathogens are also used as biocontrol agents because they are more specialized than herbivores, so the risk for non-target plants is lower. The aim of this thesis is to compare biological control with other methods used to removing invasive plants and to summarize the most significant positives and negatives of using fungal pathogens in plant biocontrol.
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Plant-soil feedback and its interactions with other factors determining plant coexistence
Opravilová, Tereza ; Kuťáková, Eliška (advisor) ; Čuda, Jan (referee)
Plant-soil feedback has been a well-studied mechanism in recent years of the success of invasive plants, the shift of species in succession, and the structure of plant communities in general. It is a process during which the plant affects the soil with its growth and these changes are reflected in the growth of other plants. Despite the large number of previous studies, relatively little attention is paid to the interaction of plant-soil feedback with other factors, which I consider important for understanding its role in natural plant communities. The aim of the work was to clarify the influence of plant-soil feedback on model species Arrhenatherum elatius and Centaurea scabiosa and to compare its influence with other factors - interspecific competition and herbivory (simulated loss of aboveground biomass). The influence of factors was investigated using biomass and changes in plant physiology, specifically chlorophyll fluorescence and the content of elements in aboveground biomass. The plant-soil feedback mechanism of the model species was assessed using the content of elements in the soil after cultivation. In the biomass of the species Arrhenatherum elatius, the factors of plant-soil feedback and competition manifested themselves in mutual interaction, when the presence of a competitor changed...
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Factors associated with invasiveness in the genus Impatiens: interaction of species traits, competition and environment
Čuda, Jan ; Pyšek, Petr (advisor) ; Kollmann, Johannes (referee) ; Prach, Karel (referee)
The aim of this thesis was to identify factors that contribute to invasiveness of species in the genus Impatiens. This genus is horticulturally attractive and includes several species that are known to have naturalized outside their native ranges, while others did not escape, in spite of being frequently cultivated. When looking for traits associated with invasiveness, it is useful to focus on congeneric species. Their traits and dispersal modes are less influenced by phylogeny, than when comparing unrelated species or even complete floras. This helps to account for traits that favour invasive species over native ones and thus identify potential invaders more precisely. A superior invader performance is attributed to a competitive advantage over native species that can lead in extreme case to competitive exclusion of the latter. Invasive and native species com- pete only if their niches overlap and the strength of competition depends on niche similarity. Importantly, invasive species are considered to be able to maintain their high competitiveness over a wide range of environmental conditions, while native ones often have narrower environ- mental optima. Lastly, competitive outcome can vary over life stages and depends on the degree of species dominance, which is rarely taken into account. Spread and...
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Application of fluidized layer of granular material in water treatment
Čuda, Jan ; Benešová, Libuše (advisor) ; Pitter, Pavel (referee)
Chemical treatment is the most often method used in water treatment in the Czech republic. It is based on dosage of destabilisation reagent into raw water, formation of separable aggregates and their separation by sand filtration. Waterworks optimalisation is predominantly carried out by change of the chemical parameters, typically by change of destabilisation reagent dose. Physical parameters in water treatment like the magnitude of the velocity gradient and period of its duration are undervalued commonly, although they have crucial effect on quality of the aggregates. Character of the aggregates (size, density, compactness) influence their separability. This study aims at evaluation of influence of the magnitude of the velocity gradient on quality of suspension formed. Infuence of stirring intensity was performed on the pilot plant situated in the Želivka waterworks, which is fed from Švihov reservoir. The pilot plant worked at two modes: 1) slow stirring by perforated baffles and 2) fast stirring by fluidised layer of granular material. Fast stirring was either aggregational (served only as stirring element), or separational (separation of aggregates proceed already in the fluidised layer) Infuence of the magnitude of velocity gradient was evaluated by aggregation test. Seperation effectivity...
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Habitat requirements and competition between native and invasive Impatiens species
Čuda, Jan ; Skálová, Hana (advisor) ; Prach, Karel (referee)
Three of Impatiens species are widespread in the Czech republic, one is native, two of them invasive. Because all species occur in relatively similar habitats, the question is, whether the invasive species can negatively affect the native species, or even the original can can be displaced. The aim of the thesis was: (i) to compare habitat requirments of the Impatiens species, (ii) to determine if the coexistence of species is possible, (iii) to assess the impact of invasive species to the original species. The investigation was carried out using two sets of permanent plots in 5 localities. In the first set with a total of 84 plots (combinations of occurrence of the three species) site characteristics as tree cover, soil humidity, slope and bare land cover were directly measured and nutrient, light, humidity and soil reaction characteristic assessed using Ellenberg indicator values. The second set contained a total of 45 plots with one of the native-invasive congener pair being removed and the intact controls. Number, cover and height of the plants were assesed. The key enviromental factors determining distribution of the species were soil moisture for I. noli-tangere and I. parviflora, and tree cover for I. glandulifera and I. parviflora. Ellenberg indicator values had poor explanation value;...
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Sources and causes of spread of newly introduced plant species
Schmiedlová, Barbora ; Münzbergová, Zuzana (advisor) ; Čuda, Jan (referee)
The bachelor's thesis is written in the form of a literature review and deals with factors that affect the current global spread of plants into new areas, and their possible invasiveness in the new areas. The aim is to verify the hypothesis that one of the main causes of the spread of new plant species (the last 50 years aprox.) to new areas could be climate change. The introductory part of the thesis explains the basic concepts (native versus non-native species, invasive species, temporarily introduced species, etc.) and lists the main factors that affect the global distribution of non-native plant species. The following is a description of the issue of current global change, focusing primarily on climate change and what impact it may have on the spread of plant species. The last part of the work focuses on newly introduced non-native plant species and on the factors that influence their global distribution the most, in comparison with plant species introduced a long time ago (more than 50 years ago). It was found that climate change does have a significant impact on the shift of the area of distribution of newly introduced plant species, especially to extreme areas (higher altitude etc.). Several selected non-native plant species, in which a shift in the range of distribution due to climate...
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Plant-soil feedback and its interactions with other factors determining plant coexistence
Opravilová, Tereza ; Kuťáková, Eliška (advisor) ; Čuda, Jan (referee)
Plant-soil feedback has been a well-studied mechanism in recent years of the success of invasive plants, the shift of species in succession, and the structure of plant communities in general. It is a process during which the plant affects the soil with its growth and these changes are reflected in the growth of other plants. Despite the large number of previous studies, relatively little attention is paid to the interaction of plant-soil feedback with other factors, which I consider important for understanding its role in natural plant communities. The aim of the work was to clarify the influence of plant-soil feedback on model species Arrhenatherum elatius and Centaurea scabiosa and to compare its influence with other factors - interspecific competition and herbivory (simulated loss of aboveground biomass). The influence of factors was investigated using biomass and changes in plant physiology, specifically chlorophyll fluorescence and the content of elements in aboveground biomass. The plant-soil feedback mechanism of the model species was assessed using the content of elements in the soil after cultivation. In the biomass of the species Arrhenatherum elatius, the factors of plant-soil feedback and competition manifested themselves in mutual interaction, when the presence of a competitor changed...
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Factors associated with invasiveness in the genus Impatiens: interaction of species traits, competition and environment
Čuda, Jan ; Pyšek, Petr (advisor) ; Kollmann, Johannes (referee) ; Prach, Karel (referee)
The aim of this thesis was to identify factors that contribute to invasiveness of species in the genus Impatiens. This genus is horticulturally attractive and includes several species that are known to have naturalized outside their native ranges, while others did not escape, in spite of being frequently cultivated. When looking for traits associated with invasiveness, it is useful to focus on congeneric species. Their traits and dispersal modes are less influenced by phylogeny, than when comparing unrelated species or even complete floras. This helps to account for traits that favour invasive species over native ones and thus identify potential invaders more precisely. A superior invader performance is attributed to a competitive advantage over native species that can lead in extreme case to competitive exclusion of the latter. Invasive and native species com- pete only if their niches overlap and the strength of competition depends on niche similarity. Importantly, invasive species are considered to be able to maintain their high competitiveness over a wide range of environmental conditions, while native ones often have narrower environ- mental optima. Lastly, competitive outcome can vary over life stages and depends on the degree of species dominance, which is rarely taken into account. Spread and...
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Effect of metapopulation structure and environmental factors on population biology of Impatiens noli-tangere infected by powdery mildew Podosphaera balsaminae
Chalupníková, Jana ; Koubek, Tomáš (advisor) ; Čuda, Jan (referee)
Studies performed on natural pathosystems revealed that the spatial structure of the metapopulation plays an important role in the development and spread of disease; phytopathological experimental studies have also revealed a significant effect of climatic factors on the presence of the disease (incidence) and the level of infection (prevalence) in populations. The aim of this study was to explore a natural pathosystem from both sides at the same time and to see which local and spatial environmental factors influence the development of pathosystem. Study focuses on population biology of natural pathosystem Podospaera balsaminae - Impatiens noli-tangere, which has not been investigated yet. In the study area (between the city Sázava (Benešov district) and village Vlkančice) host populations occurred in 78 (64 of them were infected) in 2013 and 82 populations (61 of them were infected) in 2014. Size of host populations had the strongest effect to incidence and prevalence of disease in the pathosystem. In larger populations, the disease occurred more often, developed faster and was higher. The rate of spread of the pathogen territory and the rate of population host connectivity had also strong effect. The abundance of pathogen in the studied area and the level of connectivity of host populations also...
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