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The efect of uncut grass strips on the functional diversity of selected meadow insects communities
Kapr, Jan ; Šípek, Petr (advisor) ; Harabiš, Filip (referee)
This thesis compares the species diversity and the functional diversity of three ecologically important insect taxa (Orthoptera, Heteroptera and Hymenoptera:Aculeata) between production meadows, where the uncut grass strips are left and the meadows mown in the conventional way. Leaving the uncut strips of vegetation is an example of the agri-environmental schemes which were introduced to try to mitigate the negative impact of intensive agriculture on the biodiversity of the production grassland. Here I present part of the results of a four-year study focused on the response of insect abundance and diversity to the meadow management. Based on the recorded insect species diversity, the ecological traits of the insect species were analysed. The functional diversity analysis helps to better understand the ecological relationships in production meadow communities and to evaluate the importance of this agri-environmental scheme for various insect taxonomical and functional groups. Key words: uncut grass strips, agro-envi schemes, functional diversity, production meadows, insect decline
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Reasons for the global decline of insect populations
Váňová, Barbora ; Šípek, Petr (advisor) ; Sedláček, Ondřej (referee)
This thesis deals with the issue of global decline in insect populations. Insects are one of the most numerous and diversified groups of animals in the world. This community plays irreplaceable roles in nature, contributing to the proper functioning of the entire ecosystem. However, fairly compelling evidence has now begun to emerge of long-term insect declines around the world. These declines are caused by many causes and factors that contribute to varying degrees of decline in the abundance and diversity of insect populations, and are often interrelated. The aim of this thesis is therefore to provide an overview of this global problem, and in particular its main causes. The topic has been elaborated through the study of scientific literature and subsequent presentation of the impact of individual factors on specific insect species or groups. It was found that the main reasons for the decline of insect populations are the loss of natural habitats, pollution, the spread of invasive species and pathogens, climate crisis and light pollution. Keywords: insect decline, population, biodiversity, biomass, agriculture, land use, global change
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Methodological problems of the analyses of insect decline
Chlup, Petr ; Storch, David (advisor) ; Sedláček, Ondřej (referee)
In recent years, several studies reporting a severe decline of insect populations across several continents turned the spotlight on the problem of insect decline. However, the reported declining parameters may vary, and it is necessary to differentiate between declines in biomass, abundance, diversity, or geographical range reduction. This thesis aims to summarize how the conclusions about insect decline are shaped by the methods researchers use, especially by the variables they measure, emphasizing the potential methodological issues and limitations of the various facets of insect decline. Furthermore, we offer a brief digest of the most relevant potential biases and interpretative risks threatening population monitoring surveys. The review also provides concise insight into the state of knowledge on the matter of insect population trends. Keywords: insects, insect decline, insect population trends, methodology, methodological issues
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