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The role of biotic interactions in plant invasions
Štajerová, Kateřina ; Pyšek, Petr (advisor) ; Prach, Karel (referee) ; Richardson, David M. (referee)
- ABSTRACT - The loss of co-adapted and gain of novel biotic interactions during the invasion process influence the success or failure of introduced plants. Within the present thesis, I studied diverse biotic interactions, specifically the relationships between plants and their herbivores, pollinators, fungi, and resident plant communities, and how biotic interactions can be utilized in planning effective science-based management. With my collaborators, we combined the community and biogeographical approach with the reciprocal transcontinental comparison between Eurasia and North America, based on primary data collected in the field. Of numerous hypotheses for the striking success of invasive plants, the enemy release hypothesis (ERH) is one of the most frequently tested. It asserts that the greater performance of introduced plants in non-native ranges is due to the absence, or decrease, in regulation by natural enemies that are left behind in the native range. Our results, in a broad sense, supported ERH, but we found that the magnitude of herbivore damage is context-dependent, related to the feeding guild and origin of both herbivores and plant species and that the increased plant performance in a new range might also be related to other factors, such as the shift in plant competition. Of animal-plant...
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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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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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Vegetation succession on a limestone quarry landfill
Kuťáková, Eliška ; Münzbergová, Zuzana (advisor) ; Prach, Karel (referee)
Spontaneous vegetation succession in man-made habitats, such as limestone quarries, has often been suggested as an efficient tool of restoration after abandonment of these localities. The main advantage is the fact that this process might be heading to spontaneous development of a valuable community, especially in case of proximity of a species source. The aim of this study is to describe the course of the first three years of primary succession on a limestone quarry landfill which is situated next to protected dry grassland, and also to compare the primary succession on a landfill with secondary succession running on adjacent arable land. Results based on monitoring of permanent plots and measurement of seed rain and of abiotic conditions of the site showed that besides changes in dominant species there is a rising number of species immigrating from adjacent grassland and this immigration is apparent mostly on the plots nearest to the grassland. In contrast, the number of grassland species on the arable land is not changing in time and there is also evident a massive spread of Arrhenatherum elatius. Key words: primary succession, limestone quarry, seed dispersal, dry grassland, Czech Karst, recultivation, secondary succession
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Effect of castle ruins on diversity of vegetation in the landscape
Javorský, Tomáš ; Münzbergová, Zuzana (advisor) ; Prach, Karel (referee)
Medieval castle ruins undoubtedly create the face of the Czech landscape. Moreover, the few previous studies on this topic have shown that ruins are unique and extraordinary biotope. This work aims to characterize castle vegetation on thirty examined localities (thirty ruins). Phytosociological relevés and soil samples were collected, soil depth was measured and the cover of individual layers was observed - all of this on three spots on each locality. One of the places covered castle and the other ones the nearby forests (each one was chosen differently than the other). The castle walls were sampled separately. The results show that castles not only increase the diversity of forests by hosting a higher number of species but also by a different species composition - castles have a rather large set of species with high fidelity to ruins areas. Approximately half of the uniqueness of the ruins can be explained by the soil qualities, such as higher pH, higher quantity of calcium and magnesium, the other half remains unclear notwithstanding the usage of various explanatory variables. It is certain that castle ruins are from a biological point of view exceptional, unique and they surely deserve the attention which we owe them so far.
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Explanation and risk assessment of alien woody plants invasion in Central Europe by historical and ecological factors
Křivánek, Martin ; Pyšek, Petr (advisor) ; Prach, Karel (referee) ; Richardson, David M. (referee)
Conclusions The studies presented focus on the historical and ecological traits corresponding with the successful invasion process of alien woody plants in Central Europe. In regard to invasion biology, woody plant species are among the most problematic plant life forms and constitute a high proportion of the World's worst invasive species. The irreversible changes in ecosystems often caused by invasion of these species constitute one good reason for study. The second is the large amount of data available, especially on human influence and activity (such as the intensity of planting, residence time). The reason for studying alien woody species is also reflected in their ambivalence: on the one hand, the group is represented by the most serious invasive species, while on the other hand, there is still strong pressure to plant these species for timber, food and ornamental purposes. The native woody flora of the Czech Republic contains about 280 species. The exact number of alien woody species in not known. Based on different approaches and datasets, it has been estimated to be in the order of 4,300 species. Exact data is available for a representative sample of frequently-planted alien woody species that contains 1,691 species. An estimated 128 alien species have escaped from cultivation, of which about 17...
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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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Vegetation succession at the clearings at the pine forest areas
Šmidrkalová, Monika ; Hadincová, Věroslava (advisor) ; Prach, Karel (referee)
Vegetation succession at the clearings at the pine forests areas was studied in the sandstone landscapes of the Czech Republic (Bohemian Paradise, Doksy region, Bohemian Switzerland). The aim of the study was to reveal the course of succession, the rate of changes, the factors influencing succession and the differences between the vegetation succession trajectory at the clearings and the burnt places. Space-for- time substitution method was used to record overall 249 phytocenological relevés (100 m2 ) at the clearings from 1 to 170 years, divided into 7 successional stages. The results showed the total number of species did not change significantly during the succession. There were differences in the species composition between successsional stages. The youngest successional stages (to 5 years) differed the most from the older stages by the occurence of shade-intolerant ruderal species. The eldest stages (over 40 years) were similar in the species composition. The type of planted tree and locality influenced the species composition the most within 10 years. The comparative study between the succession at the clearings and the burnt places showed significantly lower total number of species at the clearings. The development of the...
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