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Assessing ecosystem impact of and recovery from invasive plants

Author Yan SUN
Director of thesis Prof. Dr. Heinz Müller-Schärer
Co-director of thesis Dr. Urs Schaffner, CABI Europe-Switzerland & Prof. Dr. John L. Maron, University of Montana
Summary of thesis My PhD project aims to assess the ecosystem impact of and recovery from invasive plants using both biogeographic and community-based approaches. In the biogeographic approach, we will compare ecosystem impact of the same plant species in its native and its introduced range, while in the community-based approach we will compare the impact of invasive and of native dominant species in the same habitat. We will conduct field experiments in habitats that are naturally invaded by exotic plant species, and will also create experimental field plots varying in plant species richness that will be artificially invaded by exotic and native dominant species. The underlying hypotheses are that a) the ecosystem impact of an invasive plant differs fundamentally between its native and its introduced range, and that b) the ecosystem impact of an invasive species differs fundamentally from that of a dominant native species. Furthermore, we predict that c) adding an invasive alien plant species to plant communities in the introduced range results in the shift of ecosystem patterns (e.g. relationship between plant species richness and productivity), while adding the same plant species to plant communities in the native range does not. Field studies will be complemented by pot studies to disentangle the role of the genetics of the invasive species from differences in resident above- or belowground communities as drivers of the expected ecosystem impacts. Provided that either the biogeographic or the community-based approach will reveal different ecosystem impact of invasive and native plant species, we will assess whether variation in eco-physiological within the invasive species or between the invader and the native competitors can at least partially explain the observed results. In our experiments we will use C. stoebe with its three C. stoebe geo-cytotypes (diploid European, tetraploid European and tetraploid North American geocytotype) as a model species, but also include a variety of other plant species that have either become invasive in Europe or are native to Europe but have become invasive elsewhere.
Administrative delay for the defence