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Efekt podpory výskytu přirozených predátorů škůdců na zdraví a vitalitu ovocných dřevin
Bernatová, Martina
Predators (both invertebrates and vertebrates) can have a positive or negative effect on the vitality and physiological processes of woody plants. However, the mutual effect and interaction of several different groups of predators and their influence by different habitat manipulations is still not well known. For this reason, the aim of my work was to find out how biological control, i.e. manipulation to support invertebrate predators, and, conversely, the exclusion of insectivorous predators from vertebrates (birds, bats), or a combination of these two manipulations, will affect the vitality (and health status) of fruit trees, specifically pear. The experiment took place in organic pear orchards in the Zlín and South Moravian Regions. In each orchard (n = 4), 16 trees were selected and divided into groups of 4 trees differing according to the type of manipulation: a) installation of cardboard bands to support invertebrate predators, b) construction with a net to exclude the access of birds and bats, c) combination of cardboard bands and structure with net, d) control tree. The experiment started in the autumn of 2021 with the instalation of cardboard bands and in the spring of 2022 with the instalation of structures with nets for exclusion of birds. During the season (from May to September 2022), samples were collected to determine and compare leaf biomass and herbivory, fruit biomass and damage, and the efficiency of photosynthesis and the content of chlorophyll in the leaves were also measured, as well as the leaf area index. Overall, the results showed a significant positive effect of the manipulations on pear vitality. The best vitality was recorded for trees with a combination of cardboard bands and exclusion of birds and bats. The results show the importance of supporting natural predators of pests (mainly spiders). On the contrary, it is evident that these interactions could be disturbed by insectivorous birds (bats), which have a significant predation effect on spiders and thus can have a cascading effect on the vitality of fruit trees.
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Endozoochorous seed dispersal by free ranging herbivores
Lepková, Barbora
Endozoochorous dispersal of seeds is a very common phenomenon which may occur anywhere some animals feed on plants bearing mature seeds. Endozoochory has been identified as a potential driver for long-distance migration but there is a strong discrepancy between endozoochory by frugivorous animals and herbivores. Despite the fact that the latter has been observed as early as a century ago, our understanding of the herbivorous endozoochory is still limited, even more so when it comes to the free-ranging wild species of herbivores. Furthermore, the endozoochorous dispersal shows significant differences between study areas and between herbivore species suggesting we need information about the process from various study areas to draw any conclusions. This thesis aimed to: (i) research the species composition found in dung samples of wild boars and deer, (ii) quantify the effect of deer dung deposition on vegetation of dry grasslands, (iii) establish the adaptation of plant species to the passage through digestive tract, and (iv) disentangle the drivers of species composition dispersed in dung. The results of my research indicates: (i) the species composition in dung samples differs up to a point between deer and wild boars: some species are dispersed by both dispersers while other only by one of them....
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Influence of insect herbivory on plant competition
Opltová, Radka ; Kuťáková, Eliška (advisor) ; Florianová, Anna (referee)
Plant communities are influenced by many factors, such as soil properties, humidity, temperature, resource availability or competition and herbivory. This thesis summarizes current knowledge about insect herbivory and its impact on plant competition in the context of plant communities, especially in grasslands. The competition outcome depends on numerous factors, such as the competitiveness of focal as well as neighbouring plants, trade-off between fast growth and production of defensive chemicals, resource availability etc. Insect herbivory can significantly impact plant competition, and the impact depends on herbivore abundance and its specific traits, such as feeding preferences or occupied habitat. Although herbivory often reduces plant biomass, it can stabilize the community structure by suppressing strong competitors and, therefore, keeping higher plant biodiversity. Plant response to herbivory can sometimes develop over a long time, so long-term observations of changes in plant communities are necessary. It is my willingness to continue with research based on this review, within the context of a master thesis. Specifically, I would deal with the impact of belowground herbivory on seminatural mountain grassland in the Krkonoše Mountains. As a model herbivore species I chose the garden chafer...
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Interaction between herbivores and pathogens on plant
Nerandžičová, Denisa ; Koubek, Tomáš (advisor) ; Weiser, Martin (referee)
Plants are often simultaneously attacked by herbivores and phytopathogens and interactions between these antagonists have consequences for their fitness and also for plant defense. Plant disease leads to modification of plant biochemical processes which alter the host plant choice by herbivores and the availability of their nutritional resources and it induces changes in plant defense responses. Herbivores facilitate the development of plant diseases and their transmission from plant to plant. Mutual antagonism between jasmonic acid and salicylic acid signaling pathways is believed to be the main cause behind the effects of the interactions. However, according to diverse outcomes from current studies, this theory seems to be oversimplified and thus inapplicable. Effects of the interactions are driven by many more factors, from which the species specificity plays the main role. Despite this, current literature accumulates evidence that these interactions do not multiply damage from the double attack. Subsequent damage is usually more severe within individual organs but is much less severe for overall plant fitness due to the plant's ability to compensate for the losses.
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Diptera in food webs of wetland ecosystems
Pijálková, Helena ; Hadrava, Jiří (advisor) ; Kolář, Vojtěch (referee)
Families of the order Diptera are frequently found in freshwater wetlands, affecting nearly all trophic levels, serving as detritivores, herbivores and predators. Diptera are characterised by an enormous ecological variability of their larval life strategies, which often differ even within individual families. Their adults form an important connection between the aquatic environment of a wetland with its terrestrial surroundings. As a result, adults of various wetland Diptera may serve as pollinators, predators and a prey of other animals including humans. Until now, research of food webs in wetland ecosystems has been focused mainly on a few economically significant groups of Diptera such as mosquitoes, or has been focused on the role of Diptera in transfer of heavy metal from wetlands to other ecosystems. However, overall wetland dipteran diversity still remains understudied. Examining the roles of insects as well as other organisms in food webs is important for example to simulate possible consequences of introduction or extinction of certain species on ecosystems. Further research is therefore necessary to understand how do various dipteran taxa affect other organisms in wetlands as well as their surroundings. Keywords: Diptera, wetlands, ecological webs, detritivory, herbivory, predation
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Endozoochorous seed dispersal by free ranging herbivores
Lepková, Barbora ; Herben, Tomáš (advisor) ; Eycott, Amy Elizabeth (referee) ; Mudrák, Ondřej (referee)
Endozoochorous dispersal of seeds is a very common phenomenon which may occur anywhere some animals feed on plants bearing mature seeds. Endozoochory has been identified as a potential driver for long-distance migration but there is a strong discrepancy between endozoochory by frugivorous animals and herbivores. Despite the fact that the latter has been observed as early as a century ago, our understanding of the herbivorous endozoochory is still limited, even more so when it comes to the free-ranging wild species of herbivores. Furthermore, the endozoochorous dispersal shows significant differences between study areas and between herbivore species suggesting we need information about the process from various study areas to draw any conclusions. This thesis aimed to: (i) research the species composition found in dung samples of wild boars and deer, (ii) quantify the effect of deer dung deposition on vegetation of dry grasslands, (iii) establish the adaptation of plant species to the passage through digestive tract, and (iv) disentangle the drivers of species composition dispersed in dung. The results of my research indicates: (i) the species composition in dung samples differs up to a point between deer and wild boars: some species are dispersed by both dispersers while other only by one of them....
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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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Causes of limitation of plant reproduction by pollen and resource availability
Kalousková, Petra ; Janovský, Zdeněk (advisor) ; Sklenář, Petr (referee)
Plant seed production depends on many factors: their life history, the environment they grow in, and other factors such as biotic interactions. However, the immediate cause of the reduction in seed production is the lack of partners or the lack of resources available for seed production. This bachelor thesis aims to summarize and analyze the mechanisms of action and the relative importance of individual causes of limitation of plant seed production. Most plants are pollen limited at least in some seasons or in some localities, in the rest of the situations are plants resource limited. Pollen limitation can be quantitative (low pollen deposition) or qualitative (low quality of pollen). Existing theoretical models of pollen and resource limitation compare use of resources either to attract pollinators (increased flower size, increased number of rewards) and increase the chances of encountering them (change of phenology or prolongation of flowering) or to produce seeds. Plants can sometimes be seemingly pollen limited, with the pollen supplementation increasing seed production at the cost of reducing reproductive effort in the upcoming years. However, the most significant feature of pollination, which is often reflected in the alternation of reduced seed production due to insufficient pollen...
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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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Functions of secondary metabolites of lichens
Zvěřinová, Gabriela ; Svoboda, David (advisor) ; Bouda, František (referee)
This bachelor thesis is a review of available literature about lichen secondary metabolites and their functions. Lichens produce a great variety of these compounds; most of them are unique to the lichen symbiosis and are not found in higher plants. Besides the role of these compounds in chemotaxonomy and systematics, lichen secondary metabolites exhibit various biological functions and can affect biotic and abiotic interactions of lichens with their environment. Well-known and often described functions of lichen substances include especially antimicrobial, antiherbivory and antioxidant activity, allelopathy, metal homeostasis and photoprotection. This thesis is focused on these functions and summarizes current knowledge in this area. Key words: lichen, secondary metabolites, allelopathy, antimicrobial activity, herbivory, antioxidant activity, photoprotection, metal homeostasis, pollution tolerance, literary review
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