| Popis: |
Pollinators provide essential services to crop and wild plants. Declines of native and managed pollinators have prompted considerable interest in the identity and importance of native pollinators and the services they provide. In agro-ecosystems there is particular concern over the impact of landscape simplification on these communities of 'service providers', This thesis has two main aims; First, to investigate the ecosystem service of crop pollination by native insects, using ecological networks as a tool to identify pollinator interactions with crops, natural and semi-natural habitats. Pollination services to Fragaria x ananassa (strawberry), an insect-pollinated, high value crop, were used as a model system for this work. Networks were used to study interactions and spillover of insects between crop and semi-natural habitats at the local scale, the potential effects of poll in at or extinctions on pollination services, as well as pollen-transport interactions at the field scale and how they are affected by the structure of the surrounding landscape. The second aim of the thesis is {o explore the effects of sampling bias, specifically the type of sampling methodology employed, on the structure of the resulting plant-pollinator networks. The work presented in this thesis demonstrates the wide range of possible applications of plantpollinator networks to the study of crop pollination. The results reveal temporal changes in pollinator importance, spillover of pollinators across boundaries between crop and seminatural habitats and negative effects of landscape structure on pollinator communities and their interactions along with significant impacts of sampling bias on network structure. Network approaches to conservation issues reveal hidden effects of anthropogenic change on biodiversiry and are likely to be increasingly employed for such purposes in the future. The thesis ends by highlighting areas for improvement in the application of plant pollinator networks to the study of plant-pollinator community structure and pollination services, in order that ecologists gain the maximum benefit from using networks to answer questions about the effects of human activity on plant-pollinator communities and interactions. |
