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The influence of glacial meltwater on benthic algal communities in alpine streams.
Prüherová, Alžběta ; Kulichová, Jana (advisor) ; Vinšová, Petra (referee)
The specifics of glacial streams, as streams fed and influenced by mountain glacier are very tough conditions which, in these alpine habitats, last all year long. Typical features of a glacial stream are cold temperatures, oligotrophic water, high flow rate which is connected to a very good oxygen saturation and the stream level fluctuations, not only visible during the whole year, but also in a scope of a few hours during one day. Therefore populations of organisms living in these habitats have to be sufficiently adapted to such harsh environment, in order to not just survive local harsh conditions, but effectively use them to reproduce and inhabit the limited space. This thesis is focused on benthic communities of these water bodies and is a summary of knowledge from studies done mainly in Italian, Austrian and Swiss Alps. Seasonal influence of the glacier and the influence of climate change on the fragile communities inhabiting glacial streams in higher altitudes is then discussed as well as the types of streams in the alpine zone dividing said streams into several types, first into three main types according to their water source and later on into more specific types of the Alps streams according to their bed rock and other geographic variables. Glacial streams are nowadays the subject of...
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Srovnání smíšeného regresního modelu a geograficky vážené regrese na příkladu výškové funkce
Forró, Martin
The topic of this thesis is to solve spatial heterogenity in forestry models by means of utilizing linear mixed-effects models (LMM) and geographically weighted regression (GWR) to model a height-diameter curve. Both of these methods were previously tested, and they have a high potential to reduce the minimal necessary amount of data needed, and at the same time, increase precision. The data come from VŠLP Křtiny, LÚ Borky, a complex of forests utilized for educational purposes by Mendel’s university in Brno. We choosed beech as the model species. We split the data into training and validation sets for fitting, and consequent prediction assessment. Resulting models were compared with OLS fitted global model. Local OLS models were unreliable, as only a very few measured trees were available for each plot. Results were different for GWR and LMM. GWR models failed at prediction, but had good results on training plots, especially considering the reduction of autocorrelation of model residuals. LMM provided the best results for both training and validation plots
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Vliv světelných podmínek listnatých lesů I. a II. vegetačního stupně na epigeickou faunu pavouků
Surovcová, Kamila
The objective of the present study was to investigate the impact of canopy openness and associated light conditions on epigeal spider assemblages in abandoned coppice forests in order to develop conservation recommendations for forest management in lowland woodlands. In particular, I studied the effect of canopy openness gradient on species richness, abundance, functional diversity, community composition, conservation value, and degree of rareness of spiders. There was established transects reflecting the canopy openness gradient in each of the eight forest stand. A total number of 90 spider species, including high proportions of xeric specialist and red-listed threatened species. The peaks of conservation indicators, as well as spider community abundance, were shifted toward more open canopies . On the other hand, functional diversity peaked at more closed canopies followed by a rapid decrease with increasing canopy openness. Species richness was highest in the middle of the canopy openness gradient, suggesting an ecotone effect. Ordinations revealed the rapid species turnover along canopy openness gradient with presence of most conservationally important species in sparse and open conditions. The results show that the various components of biodiversity peaked at different levels of canopy openness. Therefore, the restoration and suitable management of such conditions (e.g. conservation thinning, coppice management) will retain important diversification of habitats in lowland oak forests. According to these results, even small-scale activities supporting these conditions could be suitable conservation tools to slow down the general decline of woodland biodiversity.
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The diversity of filamentous freshwater algae and factors affecting the dynamics of their communities
Hadravová, Anna-Marie ; Šťastný, Jan (advisor) ; Woodard, Kateřina (referee)
This bachelors thesis is summing up the knowleadge from published papers which are dealing with the ecology of filamentous algae communities. It is focused on how the seasonal dynamics and biotic and abiotic factors do affect the communities of filamentous algae. The first part of the thesis contains a taxonomical overview of genera of the concern. In the second part there are different types of water habitats divided by their morphology and other characteristics (depth, temperature etc.). I am dealing with the factors affecting the composition of filamentous algae communities in stagnant waters of the temperate zone. No comprehensive works focusing on this field have been published so far. My thesis presents a synthesis of knowledge from avaliable sources. The species concepts of many filamentous algae are quite confusing, that is why their species determination is so difficult. That is the reason why there are not many journal articles dealing with such ecological issues. Key words: filamentous algae, ecology, freshwater habitats, diversity
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The role of microhabitats in spatio-temporal differentiation of phytoplankton flagellates
Pusztai, Martin ; Němcová, Yvonne (advisor) ; Bílý, Michal (referee)
This thesis deals with factors structuring phytoplankton flagellates. The aim of the thesis was to investigate the role of microhabitats in spatio-temporal differentiation of lentic communities of these flagellates, which has not been rigorously examined to date. The study was conducted during 2010-2013 in the shallow littoral sites of Horní rybník, Rybníčky u Podbořánek Nature Reserve. Phytoplankton flagellates showed cyclic seasonal dynamics, which was reflected by significantly different community structure and species richness during the season. In contrast, silica-scaled chrysophytes showed a non- cyclic seasonal dynamics. The impact of the season was strongly correlated with the impact of fluctuating environmental factors - pH, conductivity and temperature. Gradient of interrelated environmental factors between the northern and southern shore together with microhabitat - substrate type played the major role and accounted for 64.4 - 75.8 % variability in the data. Microhabitat type (plankton, metaphyton, epipelon) significantly affected species richness and community structure also in the course of the season. A large number of species was assessed to prefer a certain type of microhabitat. These preferences were observed at both species and generic levels, and even at the level of the main taxonomic...
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Distribution, diversity and ecology of benthic desmids along local spatial scale
Svoboda, Pavel ; Šťastný, Jan (advisor) ; Řeháková, Klára (referee)
Besides spatial heterogeneity, an important component of diversity of the protist communities is also the variation in species assemblages through time (temporal turnover). Spatial and temporal variation in patterns of distribution and abundance of lentic microphytobenthos assemblages is often large and occurs at relatively small spatial scale. Desmids (Zygnematophyceae) often constitute a characteristic part of the microphytobenthos of peat bogs. Despite their important role in primary production and fact that they are useful indicators of ecosystem uniqueness, investigations of their seasonality and spatial distribution are scarce. In my thesis I have investigated if desmid epipelic communities are driven rather by neutral or niche-based processes, and I also focused on the factors affecting their diversity, seasonal dynamics and spatial patterns at the local spatial scale. The study was conducted at the two different types of biotopes - minerotrophic lowland peat bogs (Doksy region) and ombrotrophic raised bogs (Jizera Mountains region). Seasonal changes in species composition and diversity of assemblages were not evident. This may be affected by a monopolization effect and also that local abundance of species was positively correlated with population persistence, which suggests that high local...
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Utilization of geographically weighted regression (GWR) in forestry modeling
Quirós-Segovia, María
The diploma thesis is focused on the application of the Geographically Weighted Regression (GWR) in forestry models. This is a prospective method for coping with spatially heterogeneous data. In forestry, this method has been used previously in small areas with good results, but in this diploma thesis it is applied to a bigger area in the Region of Murcia, Spain. Main goal of the thesis is to evaluate GWR for developing of large scale height-diameter model based on data of National Forest Inventory of Spain. Final model is compared with local height-diameter model on validation plots. The obtained results are very different according to the level of input data and GWR calibration type. The best result is obtained with individual tree data and with fixed kernel calibration. In order to improve quality of GWR calibration several suggestion were made, such as change weighted functions. GWR method is highly promising because in the case of need a particular model for some large area, there is possible to make sufficiently precise model at any point of the area of interest without need of any additional measurements in particular forest stand.
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Spatial heterogeneity of physico chemical parameters and phytoplankton along the longitudinal profile of the Římov Reservoir
NOVOTNÁ, Jitka
In 2011, vertical and longitudinal gradients of temperature, oxygen, pH, conductivity and chlorophyll were measured in the Římov Reservoir. Relative distance model was employed to evaluate spatial heterogeneity of parameters measured along the longitudinal axis of the reservoir. The inflow part comprised 15 % of the overall reservoir length and was characterized with temperature, pH and chlorophyll values lower than the rest of the reservoir. Highest chlorophyll and dissolved oxygen concentrations along with pH were measured in the transition zone constituting 40 % of the reservoir length. Lacustrine zone with low chlorophyll concentration accounted for 45 % of the reservoir. It was characterized with pronounced metalimnetic and hypolimnetic oxygen minima during summer as well as the marked increase in conductivity towards bottom.
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