• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 25
  • 5
  • Tagged with
  • 30
  • 20
  • 12
  • 6
  • 6
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 5
  • 4
  • 4
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
21

Diverzita, ekologie a metodika průzkumu lišejníků pralesovitých porostů ve střední Evropě / Diversity, ecology and methods of the research of lichens in old-growth forests in Central Europe

Malíček, Jiří January 2016 (has links)
1 Abstract Forests are the native Central European vegetation, which have dominated in the landscape for the last c. 10,000 years. Stands with an oak and hornbeam dominance occupied lower elevations before human colonization, beech and silver fir-beech forests middle elevations and spruce stands at higher elevations. Only a few remnants of forests, which can be regarded as primeval or with a minimal impact of forest management, have survived in densely populated Central Europe. Examples of the most preserved primeval forests are Rothwald (Austria), Białowieża (Poland, Belorussia), Stužica/Stuzhytsia (Slovakia, Ukraine) and Boubín (Czech Republic). Although these sites are small and isolated, they are local diversity centers for many organisms, mainly for fungi, lichens and bryophytes, refugia for numerous endangered species and some of them have their last localities there. Epiphytic and epixylic lichens are an ideal model group for studies about forests because they sensitively indicate management, continuity, heterogeneity and age of a woodland. Therefore they could help us to answer many important questions about the conservation of natural forests. This thesis comprises several different points of view on lichens in Central European forests and its aim is to join these heterogeneous fields into one...
22

Atraktivita výsadeb druhů potencionálně rozšiřujících včelí pastvu pro včely / Attractive planting of species of potentially expanding bee pastures for bees

ŠEBESTA, Tomáš January 2019 (has links)
This diploma thesis entitled "Attractiveness of Planting Species with a Potential to Extend Bee Forage for Bees" discusses pollen and nectar plants planted in the Brník municipality in the Central Bohemian Region. The thesis consists of two parts. The theoretical part describes honeybees, bee plants and their pollen- and nectar production ability as well as bee forage from early spring until late autumn so as to reflect the needs of pollinators as best as possible. The practical part uses pollen analysis to microscopically analyse the representation of pollen grains of plants in the honey produced by local bee colonies. Pollen analyses of honey from own bee colonies are compared with that from bee colonies belonging to neighbouring beekeepers.
23

Význam remízků a jejich ekologických vlastností pro ptáky v intenzivně obhospodařované zemědělské krajině / The importance of woodlots and their ecological characteristics for birds in an intensively managed agricultural landscape

Rajmonová, Lenka January 2019 (has links)
Various types of woody vegetation are a key biodiversity refugee in intensively managed agricultural landscapes. However, the role of woodlots, representing an important type of such a vegetation, remains overlooked so far. Whereas the previous studies focused on the effect of their area, shape and isolation, consequences of variation in their habitat quality for biodiversity were not assessed up to now. This thesis is thus one of the first studies focusing on woodlots as a specific habitat for birds in agricultural landscape. My goals were: (I) to find out what is the bird community composition of woodlots in a Czech landscape, (II) to find out, what are the key habitat predictors of bird species richness and abundance in woodlots, (III) to describe differences in habitat preferences among various guilds and (IV) to formulate recommendations for conservational practice. I surveyed birds in 82 woodlots in an intensively managed landscape in Central Bohemia, Czechia, and measured variables describing woodlots' habitat quality together with woodlots' area, shape, isolation and types of surrounding land-use. I recorded numerous forest and non-forest bird species (57 in total), including some endangered farmland birds. The habitat variables showing significant relationships to bird community...
24

Ecological comparison of three closely related species from \kur{Myosotis palustris} group / Ecological comparison of three closely related species from \kur{Myosotis palustris} group

KOUTECKÁ, Eva January 2011 (has links)
The study is focused on comparative ecology of three closely related species from Myosotis palustris group. Importance of various functional traits of individual species was evaluated experimentally in the greenhouse (germination experiments), in the pot experiment and in the reciprocal transplant field experiment. Germination, production of clonal structures and response to various environmental conditions (competition, moisture conditions, etc.) were studied. The experimental data are supplemented with an analysis of phytosociological relationships of the studied species.
25

Atraktivita porostů pohanky pro včely / Atractivity of buckwheat for bees

KOSCHANT, Jan January 2017 (has links)
This diploma thesis ,,buckwheat attractivity for bees" deals mainly with native nectar plants for the processing of bees to honey. Work is folded in two parts. The theoretical part deals with the migration of colonies, both for nectar crops and plants with bee pollination needs. In ractical part of this thesis microscopic pollen analysis were performed and contents of pollen grains in honey from colonies, which were relocated to buckwheat growth was evaluated. Comparison of this honey with honey from the hives with similaar location, but without access to buckwheat growth was done.
26

Vliv způsobů a intenzity využívání na fytocenologický vývoj a biodiverzitu travních porostů. / The influence of way and intensity of grassland management on phytocenological dynamics and biodiversity of grasslands.

KONDRÁTOVÁ, Petra January 2013 (has links)
The main objective of this thesis was to assess the influence of methods and intensity of use on phytosociological evolution and biodiversity of grasslands. This work includes grasslands in terms of their distribution, different ways of management and use. An important goal of this work was to evaluate the incidence of plant species in grassland lying in selected localities of the Czech Budejovice, Slavošovice and Radostice. The next section was set calculation and maintenance of the water and nutrient regime on the site fallow and statistical processing of data at the sites.Based on the findings were prepared tables and graphs that confirm and in some cases disconfirm occurrence of plant species with different modes of grassland management (mowing, grazing, fallow).
27

Jak se liší druhové bohatství a početnost ptáků mezi vojenskými výcvikovými prostory a okolní krajinou? Případová studie z vojenského újezdu Hradiště / How do bird species richness and abundance differ between military training areas and surrounding landscape? A case study from the Hradiště military area

Bušek, Ondřej January 2015 (has links)
Since the beginning of the 20th century human land use changed drastically in Central Europe. These changes included: homogenization of the landscape mosaic, intensification of agriculture, urbanization and land abandonment. In turn, these changes affected bird species and perhaps most significantly manifested in population decline of open habitat birds. Therefore, it is important to investigate sites, which were not affected by the changes mentioned above, such as military training areas (MTAs) - places dedicated to training of armed forces. Previous studies have shown that MTAs seem to host remarkably high bird diversity and abundant populations of bird species of conservation concern. This may be caused by two major factors. First, closure of MTAs to all human activies besides military training spared them of the landscape changes mentioned above. Second, the military training itself produces a very heterogeneous habitat mosaic that allows coexistence of many species with different ecological requirements. To my knowledge, no study compared bird assemblages between MTAs and surrounding landscape directly. At the same time, such data are crucial to assess the value of MTAs for bird conservation reliably and, as a consequence, they enable to think more deeply about mechanism generating this value....
28

Diverzita zooplanktonu tatranských jezer v prostoru a čase / Diversity of zooplankton of Tatras lakes in space and time

Čablová, Radka January 2021 (has links)
This thesis is the first of its kind that evaluates the species composition, species richness and species abundance of zooplankton in littoral samples of 90 Tatras lakes (Western and High Tatras of Slovakia and Poland) collected in September 2004 in the context of environmental parameters of lakes and spatial relationships of individual lakes. The most frequently occurring species in the Tatras lakes in 2004 were also evaluated in terms of their occurrence in the lakes a century ago (Minkiewicz 1914, 1917 and Lityński 1913, 1917), during the period of acidification (Ertl & Vranovský 1964, Ertl et al. 1965, Hrbáček et al. 1974, Stuchlík et al. 1985) and during the period of recovery of the lakes from acidification (Hořická et al. 2006, Sacherová et al. 2006). Relationships between variables were analysed using Poisson regression, cluster analysis with multinomial regression, canonical correspondence analysis, Mantel tests and multiple negative binomial regression. Using analyses, lakes were divided into four clusters (A, B, C, D). Each cluster consisted of lakes with the same environmental and spatial factors and similar species composition. Thirteen zooplankton species (Acanthocyclops vernalis, Acroperus harpae, Alona affinis, Arctodiaptomus alpinus, Ceriodaphnia quadrangula, Cyclops abyssorum...
29

Vegetační změny českých nížinných lesů během posledních desetiletí / Vegetation changes in Czech lowland forests over the past decades

Kopecký, Martin January 2015 (has links)
Vegetation changes in Czech lowland forests over the past decades Martin Kopecký ABSTRACT To explore decadal changes in plant species diversity and composition of typical lowland forests in the Czech Republic, I compared vegetation on plots sampled decades ago with vegetation on the same plots sampled recently. First I evaluated the robustness of the approach used in my thesis. In Chapter 1, we provided the first direct test of the effect of uncertainty in original plot location on results from vegetation resurvey. We found that temporal trends in vegetation diversity and composition were comparable between exactly relocated permanent and only approximately relocated semi-permanent plots. Therefore, we conclude that the resurvey of semi-permanent plots is robust to the uncertainty in original plot location. Then, we showed that vegetation in lowland oak forest shifted from species-rich communities of thermophilous forest toward species poorer communities of mesic forest (Chapter 2). The species typical for thermophilous oak forests and nationally endangered species suffered the most significant decline. We identified as the main driver behind these changes shift from traditional coppicing toward high forest management after WWII. Further, we explored the processes behind temporal shifts in species diversity...
30

Vlastnosti rostlin určující druhové složení luk na bývalých polích / Species traits determining species composition on abandoned fields

Jarošíková, Cecílie January 2011 (has links)
Though succession is a widely studied process, there are only a few reports dealing with changes in plant functional types in the course of succession. Even fewer studies are dealing with agricultural, wet meadows, which are under continuous impact of mowing. The aim of this work is to fill this gap. The studied area is situated in south part of CHKO Slavkovský Les (region of Karlovy Vary, West Bohemia). In previous works grasslands on arable field after 15, 35 and 55 years after abandoned and continual grasslands in last 100 years were detected from historical agriculture maps. The releves on all types of grassland were made and the species pool was investigated. I this work I investigate the functional types and live-history traits of these species and I also look for Ellenberger values and changes of abiotic environment. The result suggests that the late - successional species are long-lived and have slower live cycle (they mature later). Their seeds are less persistent and have worse dispersal ability. Their seedlings are more viable and the species invest more to aboveground biomass than to underground. Late-successional species also flower earlier and shorter time, what seems to be an adaptation to mowing. I found no relationship between successional age in which the species occur and seed mass,...

Page generated in 0.0412 seconds