National Repository of Grey Literature 25 records found  1 - 10nextend  jump to record: Search took 0.01 seconds. 
Ecological specializations of birds based on spatial co-existence patterns
Petrová, Kristýna ; Hořák, David (advisor) ; Weiser, Martin (referee)
Ecological specialization based on co-existence patterns is new methodology used for niche breadth measurement using co-existing community with occupancy data. It results in generalist-specialist continuum according to value of speciali- zation index. The aim of this thesis was testing index stability at spatial and tem- poral scale, compare this specialization index with other specialization indices and study changes in specialization with time changes in occupancy. Specialization was quantified using data of breeding birds atlases in the Czech Republic and Europe using two selected indices Theta and Simpson. Methodology seems to be sensitive to spatial scale. Instability appears at small scale for birds, stability and correlation between indices increase with gre- ater scale. Problems with using point counts corresponds to their unsuitability encompass birds' habitats, especially for water dependent birds. Correlations be- tween different time periods are stronger at greater spatial scale. Specialization based on co-existence patterns correlates with specialization according to experts' opinions. Results from comparing changes in specialization with changes in occu- pancy suggest, that most of species tend to leave more diverse sites with occupancy decline.
Spatial distribution of plant roots in heterogeneous soils
Hrouda, Adam ; Weiser, Martin (advisor) ; Kuťáková, Eliška (referee)
In natural ecosystems, water and mineral nutrients are unevenly distributed in soil. Plants respond to this heterogeneity with active phenotypic plasticity of their root system. This plasticity can be either morphological, physiological or their combination. Both single-plant and competition experiments reveal that species differ in responses to heterogeneous distribution of nutrients. Based on observed differences, several theories emerged that describe the mechanisms of species coexistence in plant communities. Thanks to many experimental studies we currently have a better understanding of plastic root responses to soil heterogeneity, but the role of root plasticity in community establishment and development remains unclear. Precise observation of field soil heterogeneity is needed together with more realistic experiments reflecting the natural environment.
Seasonal variability of plant secondary metabolism (Artemisia sp.)
Koutská, Barbora ; Weiser, Martin (advisor) ; Dostál, Petr (referee)
Plant secondary metabolites (SM) are widely used by humans in many ways (pharmacy, biotechnology etc.). For making their use even more effective, it is important to know the seasonality of these chemicals in plants and what affect those changes. Three Artemisia species (Artemisia annua, A. absinthium, A. vulgaris) were cultivated during one vegetation season (from April to September 2016). Plant growth parameters and the beginning of their generative stages were observed, and leaf samples were collected regularly. Samples of some plants were collected repeatedly. A generalist herbivore (migratory locust), was used as a proxy for studying changes in plant secondary metabolism during the vegetation season. The results proved presence of defence secondary metabolites in plants except A. vulgaris species where the role of SM in defence was not shown. Levels of SM changed nonlinearly during the vegetational season and were time-dependent. Plant size did not influence the levels of SM in plants. Levels of SM were low at the beginning of the experiment followed by rapid increase and remaining on maximal levels. The plants which lost their biomass repetitively grew slowly and bloomed later than the plants which were clipped only once. A delay trend showing seasonality of the plant SM was not proved. In...
Changes in timing of germination caused by neighbouring seeds and how it is connected with species traits.
Kos, Pavel ; Weiser, Martin (advisor) ; Hadincová, Věroslava (referee)
The time when the seed germinates is very important. Ability to change the time of germination may be very advantageous. It allows the emerging seed to choose the best time according to abiotic conditions, and also to avoid of competition with neighbouring individuals. The seed reacts not only on adult plants and seedlings, but also on other seeds, with which is able to communicate. For a better understanding to this mechanism I conducted an experimental study with twenty-six species. The species were selected according to their position in long succession seres of mesic/xeric abandoned fields in Český kras. The seeds were left to germinate in pairs in all combinations among them. Here I present the results where I show how the time of emergence changes, depending on presence of neighbouring seed. Also, I show how these changes in germination are related to species specific traits. Out of this, I tried to influence communication between seeds by adding activated carbon. Activated carbon should stop the communication by highly absorbing surface. The time of germination of seeds which germinated alone was not proportional to the time of germination of seeds which germinated with neighbours. This correlation showed up like nonlinear, late-emerging seeds emerging unproportionally later when emerging...
Use of Nutritional Supplements in Individual Sport Sectors
Weiser, Martin ; Hájková, Jana (advisor) ; Svobodová, Irena (referee)
The aim of the diploma thesis was to determine, which nutritional supplements are selected by athletes of strength and endurance sports branches and what is the reason for their option. The theoretical part characterizes the 8 selected sports sector from point of view of the sport performance structure. There is also mentioned the issue of nutritional supplements, their division, legislation or general recommendations for the use in sport. The last chapter deals with the requirements for the use of nutritional supplements in different periods with respect to the branche of sport. Research part has specifically determined the nutritional strategy for athletes in the field of mentioned food supplements at strength and endurance-oriented sports disciplines by using the questionnaire. The research is supported by an interview with an expert nutritionist and sports through collaboration with the staff of the Centre for Sports of the Ministry of Interior
Plant body as a behavioural platform - an ecologist's insight
Weiser, Martin ; Herben, Tomáš (advisor) ; Šmilauer, Petr (referee) ; Novoplansky, Ariel (referee)
Conceptualisation of plant behaviour, or plant phenotypic plasticity, has been proven to be useful both on the ecosystem scale and on the level of individuals, as it allows to predict differentiation of species across ecosystems or results of interactions among individuals. Between these extremes is a vast array of processes that drive community assembly. These processes are difficult to predict, be it at the individual level or based on whether a whole species is plastic or non-plastic. These processes are traditionally investigated at the species level. In this thesis, however, I instead show how species-specific life histories delineate plant behaviour. I hope to convince the reader that it is the plant body, or at least its species-specific properties, not merely its non-specific, theoretical degree of plasticity, that should be used to explain actual cases where plant behaviour underpins species coexistence. As evidence for my case, I present four studies, each of them dealing with different part of the plant body that underlies different aspects of plant behaviour. In the first study, I show how species' life- history traits are coordinated with their responses to neighbour presence and resource shortage, both of these delivered in the form of changing light quantity and quality. Not only the...
Ecological determinants of plant clonal growth
Martincová, Nina ; Weiser, Martin (advisor) ; Latzel, Vít (referee)
The aim of this study is to provide a further insight into influence of environment on clonal plants. The study focuses particularly on effects of fertilization level and light availability on production and growth of clonal organs. Three experiments were carried out within the study, targeted to elicit influence of these environmental conditions or clonal interactions on six species of clonal plants. Interspecies dependencies on these conditions was compared, regarding habitat occurrence of these species. A comparison was made also between species producing rhizomes and stolons. The experiments revealed that five of six studied species show significant relationship among at least one environmental condition and parameters of clonal reproduction. Most of the species showed higher elongation and production of clonal organs in relation to fertilization level. On the contrary, only three species reacted significantly to the light availability level by alternation of at least one parameter of clonal reproduction and the light availability level affected each species differently. A strong influence on production and elongation of clonal organs had also a size of a plant. There was not found significant difference in influence of environmental conditions on clonal reproduction among plant families. It...
Habitat dependence of persistence of clonal connection in plants
Martincová, Nina ; Weiser, Martin (advisor) ; Koubek, Tomáš (referee)
The review is about the role of environment to the longevity of connection in clonal plants. The first part is dealing with theoretical models, which describe the interaction of plants with different strategies in longevity of clonal connection in a model habitat. Subsequently, it analyses concrete attributes of the environment - heterogeneity, carrying capacity, amount of disturbances and competition. This part focuses more thoroughly on their impact on persistence of clonal connection and strategy of clonal reproduction in general. The last part refers to some other phenomena which could influence the length of persistence of a clonal connection.

National Repository of Grey Literature : 25 records found   1 - 10nextend  jump to record:
See also: similar author names
1 Weiser, Michael
2 Weiser, Michał
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