Do plants establish more successfully in species-poor or species-rich meadows?
Investigate how species richness in a meadow and competition from surrounding vegetation affect the survival and growth of meadow plants. You will participate in a field experiment at thirteen sites and compare its results with those of previous seed-sowing and growth-chamber experiments.
Effects of species richness and surrounding vegetation on the establishment and growth of meadow species.
Questions: Do sown and transplanted meadow species establish more readily in species-poor or species-rich meadows? Does the effect of surrounding vegetation vary along gradients of species richness and site fertility? Does plant growth in natural vegetation reflect responses observed under standardised conditions?
Background: Not all species present in the surrounding landscape can establish at every potentially suitable site. Their success may be influenced by the species richness and productivity of the local community, site characteristics and competition from neighbouring plants. Species-rich communities may use available resources more efficiently, leaving fewer opportunities for additional plants to establish. However, species richness may also be associated with environmental conditions, such as soil fertility. Separating the effects of species richness, environmental conditions and surrounding vegetation is therefore challenging.
A seed-sowing experiment involving six common meadow species has been conducted at thirteen meadow sites differing in species richness. Seeds were sown into intact vegetation and into small plots from which surrounding plants had been removed. The results will reveal how germination and early survival vary along the species richness gradient. A subsequent transplant experiment will examine how the survival and growth of pre-grown seedlings, and the effects of surrounding vegetation, vary along this gradient. The findings can also be compared with a completed growth-chamber experiment that examined the responses of the same species to soil fertility under standardised conditions.
Objectives: To transplant pre-grown seedlings of six meadow species into intact vegetation and into plots without surrounding plants at thirteen sites. To monitor their survival and growth during the growing season and determine biomass and relative growth rate at the end of the experiment. To assess how plant growth and the effects of surrounding vegetation vary along gradients of species richness and site conditions and compare the results with the previous seed-sowing and growth-chamber experiments.
What the student will do and learn: The student will participate in transplanting and harvesting plants in the field, monitoring their survival and growth, and processing data from several related experiments. Depending on the scope of the project, they may also measure specific leaf area or biomass allocation between aboveground and belowground plant parts. They will learn to analyse relationships among community species richness, site conditions and the performance of transplanted plants.
Supervisor: Eva Janíková (
Long-term changes in hygrophilous vegetation
More frequent and intense droughts can substantially alter vegetation in wet habitats and threaten species that depend on high water availability. The aim of this thesis is to resurvey previously studied sites and determine how the occurrence and abundance of sedges and other plant species have changed. The work will test whether species with higher soil moisture requirements show the greatest declines.
Questions: How have populations of the monitored hygrophilous species and the plant community changed over several years that included periods of severe drought? Are declines concentrated among species associated with high soil moisture, while species favoring drier conditions remain stable or expand?
Background: Climate change and increasingly frequent droughts may substantially affect plant communities associated with wet habitats. Sedges and other hygrophilous species may be particularly sensitive, as their occurrence is closely linked to water availability. Long-term data from the same sites provide an opportunity to track changes in vegetation over time rather than simply compare different sites.
Objectives: An extensive dataset collected several years ago, focusing primarily on sedges and other species of wet habitats, is available for this project. The aim is to revisit the original sites and use the same methods to determine how populations of the monitored species and the plant community have changed over several years that included periods of severe drought.
What the student will do and learn: The student will participate in field surveys of previously studied sites and learn to work with long-term vegetation data. They will record changes in the occurrence and abundance of individual species, local population extinctions, changes in species richness and overall vegetation composition. The project will also involve interpreting the observed changes in relation to the ecological requirements of the species.
Supervisor: Aleš Lisner (
When is a young plant likely to succeed? The importance of size for establishment in a meadow
Investigate whether larger seedlings survive better among surrounding plants and whether the critical size for survival differs among species. You will gain experience in pre-growing plants, setting up a field experiment and monitoring their survival and growth.
Effects of initial plant size on survival and growth in a meadow community
Questions: How does initial size affect a young plant’s ability to survive in intact vegetation? Does a larger initial size help plants overcome competition from surrounding vegetation? Does the importance of initial size differ among plant species?
Background: The period between germination and maturity is one of the most vulnerable stages of a plant’s life cycle. Small seedlings are susceptible to drought, shading and competition from neighbouring plants. As they increase in size, they may gain better access to light and develop more extensive root systems, but it remains unclear when their chances of survival improve substantially. This critical size may differ among species with contrasting growth strategies. Identifying the stage at which mortality is greatest helps explain plant community assembly and the causes of unsuccessful meadow restoration.
Objectives: To grow selected meadow species to several size classes or developmental stages and transplant them simultaneously into intact vegetation and into plots without surrounding plants. To monitor their survival and growth and determine how the effect of surrounding vegetation changes with initial plant size. To compare species in terms of the size at which survival probability increases substantially.
What the student will do and learn: The student will participate in pre-growing plants, measuring their initial size and establishing a field experiment. They will monitor the survival and growth of individual plants, carry out the final harvest, and learn to analyse survival data and growth responses.
Supervisor: Eva Janíková (
Does phenology differ between rare and dominant species?
Differences in the timing of growth during the growing season may reduce competition among species and promote their long-term coexistence. The aim of this thesis is to determine whether rare and dominant species in meadow communities differ in their phenology and whether rare species reach their seasonal peak at a different time from dominant species. Selected species characteristics, such as cover, height and reproductive stage, will be monitored regularly throughout the season.
Questions: Can differences in the timing of growth during the growing season contribute to the coexistence of rare and dominant species? Do rare species exploit different parts of the growing season from dominant species?
Background: The long-term coexistence of many species may be supported not only by differences in their use of space and resources, but also by differences in the timing of growth. Species that reach their seasonal peaks at different times may compete less strongly than species that are active simultaneously. This mechanism could be particularly important for rare species that persist over the long term in communities dominated by a few abundant species.
Objectives: The aim is to determine whether rare and dominant species in meadow communities differ in their phenology and whether rare species tend to avoid temporal overlap with dominant species. Throughout the growing season, selected species will be monitored at regular intervals for characteristics such as cover, height, biomass and reproductive stage. This will allow the timing of each species’ seasonal peak to be identified and the phenological strategies of rare and dominant species to be compared.
What the student will do and learn: The student will gain experience in repeated field monitoring of plants throughout the growing season, working with ecological data and conducting statistical analyses.
Supervisor: Aleš Lisner (
How long can seeds wait for an opportunity to germinate?
Explore how seed provenance and the soil environment affect seed longevity and the ability to germinate. You will participate in seed collection and storage in the field, germination tests and long-term monitoring of the experiment.
Do seed provenance and the soil environment affect seed longevity and germinability?
Questions: Do seeds from ecologically contrasting habitats differ in survival and germinability? Is seed longevity more strongly influenced by provenance or by the environment in which seeds are buried?
Background: Many plants form a soil seed bank that allows them to persist through periods unsuitable for germination and growth. However, seeds of the same species may originate from populations exposed to different moisture conditions, temperatures or levels of productivity. These differences may be reflected in seed dormancy, longevity and responses to germination conditions.
Objectives: To collect seeds of selected species from ecologically contrasting habitats, bury them in permeable bags in the soil, and test their viability and germinability after different periods. To compare the effects of species identity, seed provenance, burial site and burial duration. This topic is particularly suitable for a longer-term project, with the possibility of continuation at master’s level.
What the student will do and learn: The student will participate in collecting and burying seeds in the field, testing their viability and germinability, and monitoring the experiment over the long term. They will learn to prepare germination tests, record germination over time, and statistically evaluate the effects of seed provenance and environmental conditions.
Supervisor: Eva Janíková (
Does the relationship between productivity and species richness change throughout the growing season?
The productivity of plant communities is often estimated from a single biomass measurement, yet different communities may reach their seasonal peak at different times. The aim of this thesis is to use repeated measurements of biomass and species composition to determine whether the relationship between productivity and species richness changes throughout the growing season and what role the phenology of dominant species plays in these changes.
Questions: Does the stage of the growing season influence the relationship between productivity and species richness? Are these changes associated with the phenology of dominant species?
Background: The relationship between productivity and species richness is a classic question in ecology. However, productivity is estimated from a single harvest of aboveground biomass, usually carried out around the expected seasonal peak in vegetation biomass. Communities and their dominant species reach peak biomass at different times, so a single measurement may not capture all sites at the same stage of seasonal development.
Objectives: The aim is to determine how the relationship between productivity and species richness changes throughout the growing season. Aboveground biomass and community species composition will be assessed repeatedly at sites with a productivity gradient. This will allow the relationship between species richness and biomass to be compared, for example, before, during and after the seasonal peak. The project may also examine the role of dominant species, particularly whether their phenology determines when the relationship between productivity and species richness is strongest or weakest.
What the student will do and learn: The student will gain experience in repeated sampling of aboveground biomass and recording species composition throughout the growing season. They will learn to work with ecological data, conduct statistical analyses and interpret the results.
Supervisor: Aleš Lisner (
Hidden competition belowground: are plants more limited by root competition or shading?
Is the growth of meadow plants more strongly limited by shading or by root competition for water and nutrients? In a field experiment, you will test methods for separating aboveground and belowground competition and determine whether their relative importance changes with fertilization.
The relative importance of belowground and aboveground competition in meadow communities
Questions: Is the growth of meadow plants more strongly affected by aboveground competition for light or by belowground competition for water and nutrients? Does their relative importance differ between fertilised and unfertilised plots?
Background: Plants compete not only for light but also for space, water and nutrients in the soil. Belowground competition is difficult to observe directly, and separating its effects from those of aboveground competition is experimentally challenging. Its importance may vary with site productivity: shading may be more intense in productive vegetation, whereas competition for soil resources may predominate under less productive or dry conditions.
Objectives: To compare the effects of aboveground and belowground competition using experimental plants. To evaluate different methods of reducing root competition and determine whether the growth of experimental plants is more strongly limited by aboveground or belowground competition. To establish whether the importance of these two components of competition differs between fertilized and unfertilized plots. The specific scope of the experiment will be adjusted depending on the type of thesis; the effects of fertilization and more detailed measurements of functional traits may be included, particularly in a master’s thesis.
What the student will do and learn: The student will participate in setting up a field experiment and gain experience with different methods of reducing aboveground and belowground competition. They will monitor the growth of experimental plants, measure their functional traits and conduct statistical analyses of ecological data.
Supervisor: Eva Janíková (
Seeds or vegetative shoots? How competition alters plant reproduction?
How does competition from surrounding vegetation affect the reproduction of meadow plants? In a field experiment, you will compare flower and seed production with vegetative spread through vegetative shoots or daughter rosettes and determine whether plants alter their investment in reproduction under competition.
Effects of competition on reproductive allocation in meadow plants
Questions: Do plants surrounded by dense vegetation invest less in reproduction? Does competition alter the balance between seed production and vegetative spread? Do these responses differ among species with different capacities for vegetative spread?
Background: Plants have limited resources that they allocate among growth, survival and reproduction. They can produce seeds, but they can also spread vegetatively through shoots, rhizomes or daughter rosettes. Competition from surrounding vegetation may reduce total reproductive output, but it may also alter how plants allocate resources among different reproductive functions.
Objectives: For selected meadow species, to compare the onset of flowering, flower and seed number, seed mass, vegetative spread and reproductive allocation between plants growing in intact vegetation and those in plots with reduced competition. To determine whether differences arise solely from smaller plant size or whether competition alters relative investment in sexual and vegetative reproduction.
What the student will do and learn: The student will participate in a field experiment, monitor flowering and vegetative spread in meadow plants, and measure reproductive traits such as the number of flowers, seeds, vegetative shoots or daughter rosettes. They will also gain experience in harvesting and sorting biomass, collecting, counting and weighing seeds, and conducting statistical analyses of ecological data.
Supervisor: Eva Janíková (
