| Summary: | Abstract This thesis operates at two levels of ecological research, describing the effects of withdrawal and re-introduction of management on grasslands. The aim of the community-level survey was to explore the effects of abandonment, mowing and grazing on semi-natural meadows in northern Finland. At the species level, the aim was to evaluate the responses of three monocarpic meadow species to various degrees of simulated grazing under natural growth conditions. The community-level studies suggest that strongly competitive grass species with rapid vegetative growth, especially those forming tussocks, are able to retain or increase their cover in abandoned meadows. However, most species are able to persist in a meadow for a long time after abandonment, even when a group of immigrants arrive. This leads to a temporary increase in species diversity, and it may therefore be used as an indicator of ongoing succession. Nevertheless, abandonment is harmful for the rare archaeophytic species in the long run. Late mowing does not have extensive short-term impacts on grass-dominated semi-natural meadows. Therefore, it is neither an efficient nor a substitutional way of management when the goal is to restore a formerly grazed pasture. Mowing executed early in the season may, however, be a more appropriate way of inducing changes in species composition and enhancing species richness. According to the results of the species-level studies, Erysimum strictum and Rhinanthus minor tolerate well minor apical damage, while more severe damage has a detrimental impact on the performance of both species. The observed differences in regrowth responses between the two species are presumably due to their different habitat requirements in relation to competition. The species-level experiment with two late-flowering populations of field gentian Gentianella campestris ssp. campestris revealed that the southern, Swedish population that has been regularly grazed and mown overcompensated for the intermediate (50%) damage level, whereas the ...
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