Summary1 Increased occurrence of high-flow events as a result of climate change may affect the dispersal success of an invasive plant species Mimulus guttatus and may result in range expansion. Predicted changes in climate point to a continuation of the recent observed trends in increased precipitation and high-flow events in Northern Europe. 2 The study focused on the dispersal characteristics of M. guttatus, and especially the roles of vegetative fragmentation with increasing water velocities, subsequent fragment survival, regeneration and colonization, as well as the buoyancy, survival and germination success of seeds. 3 M. guttatus was found to fragment readily under velocities typical of high flow conditions and even small fragments had high survival, regeneration and colonization capacity. 4 Large numbers of small (< 0.02 mg) seeds are produced; however, seeds have a short buoyancy period so the timing and magnitude of high-flow events is crucial in determining potential dispersal distances. Seeds germinate readily both in water and on sand with an average 33% germination within 9 days. 5 The dual strategy of dispersal by vegetative fragments and seeds, together with the opportunity of dispersing the two types of propagules during different periods of the year, facilitates local dominance by M. guttatus as well as long-distance colonization. As a result, the rate of spread of M. guttatus into inundation communities along rivers is likely to increase with more frequent high-flow events, especially if these coincide with the growing season. Thus, predicting the response of riparian invasive species to environmental change requires not only an understanding of the role of climate in plant demography but also the impact of changes in hydrology on rates of spread.

Changing land use has a major impact on lichen diversity. This study attempts to identify patterns or trends of lichen functional groups along a land use gradient, ranging from natural forests to open agricultural landscape. In eight countries, covering six main European biogeographic regions, lichen vegetation was assessed according to a standardized scheme. Data on reproductive, vegetative and ecological traits was compiled and relative species richness for all classes of all traits calculated. Relationships between the land use gradient and relative species richness of trait classes were analysed. Open and intensively managed landscapes harbour more fertile species while sterile species are relatively more important in forests. This finding is also supported by analyses of different classes of dispersal propagules. The importance of species with the principal photobiont Trebouxia s.l. increases linearly with intensification of land use. A converse pattern is revealed by species with Trentepohlia. Concerning substratum specialization only generalists show an effect along the land use intensity gradient. Their relative species richness decreases from landscapes dominated by forests to open agricultural landscape. A considerable decline in the rare lichen species richness as a result of land intensification is predicted.

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