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Ecophysiology of photosynthesis of wetland grasses
MEJDOVÁ, Markéta
The wetland ecosystems play an important role in the global carbon cycle. The individual processes of carbon (C) exchange and sequestration of vegetation are studied using different approaches and methods. Using by the photosynthesis light curves can be determined parameters of photosynthesis (Pmax -maximum rate of photosynthesis, Icomp- compensation point, Rd- dark respiration, - maximum quantum yield) of individual plant species. Knowledge of these parameters will allow us to understand what role plants play in the processes of C exchange and sequestration. The main goal of this work was to determine the parameters of the photosynthesis light curve of dominant plant species in the sedge-grass marsh stand of Mokré louky near to Třeboň town. Further to evaluate whether the investigated plant species differ in individual photosynthetic parameters and whether they are affected by environmental conditions. The work took place during the vegetation period of 2013 at weekly intervals. Vegetation mapping was performed also in 2013 and consequently in 2017. For a comprehensive knowledge of the ecosystem, the production characteristics of the investigated plant species and the determination of the big-leaf parameters of the light curve for whole ecosystem. Estimated carbon uptake by the hypothetical big-leaf was compared with net ecosystem exchange (NEE) measured by eddy-covariance (EC) system. The investigated plant species differed significantly in the Pmax parameter and can be divided into three groups according to it. The first group with the highest average value of Pmax includes Glyceria maxima (18.36 ?mol m-2 s-1) and Acorus calamus (16.61 ?mol m-2 s-1). The second group includes Carex acuta (10.83 ?mol m-2 s-1) and Phalaris arundinacea (9.41 ?mol m-2 s-1). And in the third groups with the lowest average value of Pmax includes Calamagrostis canescens (7.02 ?mol m-2 s-1). Pmax was higher in early summer and then gradually decreased. Higher Rd was observed, for example, at the beginning of the growth season; after the flood and especially at the end of the growing season. The Pmax was significantly affected by water level fluctuations in Phalaris arundinacea and Calamagrostis canescens. The Pmax in Phalaris arundinacea was also significantly affected by the June floods. The conductivity of the stomata did not affect the Pmax parameter, but was significantly affected by the water level in all examined plant species. During vegetation mapping in 2013, the following relative representation of individual plant species was processed: Phalaris arundinacea 35 %, Carex acuta 28.6 %, Glyceria maxima 16.5 %, Acorus calamus 1.2 %, and Calamagrostis canescens 18.7 %. Rate of Pn and NEE had a similar seasonal course (R2=0,859 - 0,998), but Pn reached higher values than NEE measured by EC method.
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Population genetic aspects of plant invasions: studies of genetic and cytotype variability in invasive and native populations of \kur{Phalaris arundinacea} L. a \kur{Myriophyllum} sp.
KÁVOVÁ, Tereza
One of the hypotheses about the causes of invasive transmission of Phalaris arundinacea in the US is, that this species have repeatively introducted from Europe or by hybridization of the introduced genotypes with the native species. This is the same situation as Phragmites australis. Part of this intercontinental gene flow is enhanced by the production of Phalaris cultivars in Minnesota. The consequences of these exchanges have a significant impact on the management of invasive crops from both continents. Previous studies confirm only minimal morphological heterogeneity between cultivated and native (wild) forms of Phalaris arundinacea. In Phalaris arundinacea, we analyzed genetic similarities and differences between the US populations (Minnesota) and population of the Czech Republic. The extent of genetic variation in native and invasive populations was compared using ISSR markers. The occurence of commercial genotypes was observed across the full spectrum of invasive genotypes, which suggests a relatively frequent exchange of genes among forage, ornamental, and native US populations. The genus Myriophyllum is mainly significant because of its invasive species, which have always been in a special position as the course of ecological and evolutionary changes may be observed in real time. In Central Europe it is represented by three native species (M. spicatum L., M. alterniflorum and M. verticillatum) and two non-native species of North American M. heterophyllum and South American M. aquaticum. Species M. spicatum, together with M. heterophyllum and M. aquaticum, is one of the most important invasive plants that, due to their aggressive growth, cause many problems, especially in North America. The main theme of this Ph.D. is the evaluation of the role of polyploidization in processes leading to invasive character of some species of the genus Myriophyllum in the USA, cytological and population-genetic comparison of native (Eurasia) and invasive populations (US) of Myriophyllum spicatum. Moreover, possible "Pools" of genetic and cytotype variability of invasive populations and evaluation of usability of simple genome size were determinated in taxonomic determination by classical morphological procedure of unclassifiable plants, which might reduce the cost and efficiency of invasive stool biomonitoring and thus the management of its invasive populations
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The effect of nutrient level on plant structure and production in a wet grassland: a field study
KÁPLOVÁ, Miroslava
Since the 1950s, agricultural intensification has affected the structure and functioning of ecological systems including wet grasslands. Our study site, a wet grassland near Třeboň, Czech Republic, was historically a sedge meadow, but increased nutrient additions, a long-lasting flood in 2002 and changed mowing patterns resulted in domination by Phalaris arundinacea. The aim of the study was to determine how different nutrient conditions may affect plant structure and production in a wet grassland used for hay production.
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Effects of nutrients and water level on \kur{Phalaris arundinacea} growth
KÁPLOVÁ, Miroslava
This thesis is an extension of my Bc. thesis. Based upon previously conducted research in a wet grassland, Mokré Louky, near Třeboň, Czech Republic, a mesocosm experiment was designed for investigating the effect of two nutrient regimes (non fertilized / fertilized) and three flooding regimes (saturated / spring flood / flooded) on Carex acuta and Phalaris arundinacea plants to determine the effect of management type for restoring a more diverse wet meadows system.
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SEASONAL DEVELOPMENT OF ABOVEGROUND BIOMASS AND LEAF AREA INDEX IN A SELECTED MONODOMINANT STAND OF EUTROPHIC WET MEADOW
RYCHTEROVÁ, Jana
The bachelor thesis is part of the project of Ministry of Enviroment of the Czech Republic entitled CzechCarbo {--} the Study of the Carbon Cycle in Terrestrial Ecosystems of the Czech Republic, which is coordinated by the Institute of System Biology and Ecology of the Academy of Sciences of the Czech Republic. This work is part of team research focussed on aboveground production of a eutrophic herbaceous wetland, the Wet Meadows near Třeboň, where the carbon balance and cycle are studied within the CzechCarbo project. The work deals with aboveground production and leaf area index in Phalaris arundinacea (L.), which dominates the vegetation in the seasonally flooded part of the Wet Meadows. The studied stand dominanted by Phalaris arundinacea is highly productive. Its annual aboveground production attained 1407,6 g.m-2. The highest value of crop gropwth rate (CGR), attained in May, was 10,67 g.m-2.den-1. In the same time period, the relative growth rate (RGR) was 56,9 mg.g-1.den-1. The results gained in 2006 are discussed with results of previous research focused on the biomass and production of P. arunadinacea in the Wet Meadows and other localities in South Bohemia.
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