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Causes of bee loss (Anthophila) in the landscape
Bureš, Vít ; Straka, Jakub (advisor) ; Tropek, Robert (referee)
Bees (Anthophila) are one of the most important pollinators in the majority of Earth's biotopes. They interact with almost one-fifth of flowering plants and together with other pollinators they secure one- third of human food sources. Since the end of World war II,along-term decrease in numbers of bees and other insects is observed due to degradation of natural habitats, expansion of agriculture, pesticide usage, parasites, and infections. In North America and Europe, several studies reported a significant loss of bee diversity and abundance. The situation in tropics is unclear and there is not enough evidence if bees are threatened there. Specific changes in relation to the decrease of the bee population are observed in the case of honey bee (Apis mellifera). Due to human beekeeping activities and specific honey bee attributes such as bigger body size or tolerance to lower temperature, honey bees show different trends in their abundance than other bees. This study discusses the causes of these losses and possible future consequences, for example, the collapse of ecosystems as a result of pollination crisis or lack of human food. On the other hand, several phenomena such as extensive agriculture, green cities, or wildfires have a positive impact on bee abundance and diversity. This thesis presents...
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Long-term population trends of birds in North America and Europe: a metaanalysis of existing studies
Říhová, Jana ; Reif, Jiří (advisor) ; Voříšek, Petr (referee)
Since the beginning of the last century there have been significant changes in the environment, farming and the landscape structure. Because birds are one of the longest- studied groups of organisms and are considered to be good indicators of environmental quality, it is advisable to relate environmental changes to changes in bird abundance. Understanding these relationships enables better and more accurate formulation of conservation plans and priorities, and therefore a large number of studies were dedicated to them. Although these studies achieved great progress in the knowledge of the most important factors that affect bird populations, their findings remained somewhat incomplete and fragmentary due to their limited temporal and/or spatial coverage. Therefore, it was not entirely clear which patterns are general and which are confined to some specific regional conditions. The fill this knowledge gap, I collected all studies on long-term trends in bird abundance in Europe and North America, which I was aware of, and made a meta-analysis of their results. Using linear mixed-effects models, I found a significant decrease in open-habitat species, probably as a result of agricultural intensification and abandonment of agricultural land. This pattern was consistent regardless of region or time period...
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