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Disentangling the interplay of generative and vegetative propagation among different functional groups during gap colonization in meadows



  1. Meadow plant communities are commonly driven by strong competition, and the colonization of gaps plays an important role in the maintenance of their species diversity. Despite this, species-specific information about the dynamics of vegetative and generative propagation, and on the role of seed bank and seed rain, is rather scarce.

  2. In a 3-year manipulative experiment, we aimed to disentangle the effects of seed bank, seed rain and vegetative propagation in vegetation and during colonization of artificial gaps in a mesotrophic meadow. Vegetative propagation was manipulated by felting and the presence of the seed bank by soil sterilization using gamma radiation. We focused on the dynamics of four main species groups with different regeneration strategies: dicots, Cyperaceae, Juncaceae and Poaceae. The shift from seedling dominance in early stages towards vegetative resprouts dominating at a later stage in the gap colonization process differed considerably among the four species groups.

  3. Dicots and Juncaceae, regenerating frequently from the seed bank, acted as pioneer species, and determined species composition of newly disturbed sites. Seed rain became crucial later in the season and resulted in shifting dominance to the more competitive Poaceae. Stress-tolerating Cyperaceae were colonizing the gaps vegetatively mainly towards the end of the experiment. While graminoids showed preference for growing into gaps clonally, dicots propagated vegetatively mostly within intact vegetation.

  4. Although seed rain soon equalized seedling numbers in plots with and without a seed bank, the presence of a seed bank proved to be crucial for certain species, and its effect on species diversity remained positive in all functional groups for the duration of the experiment, demonstrating the importance of a seed bank for the maintenance of species diversity. Nevertheless, seedling assembly converged to a similar functional composition in all gap types after 3 years. We have not detected any competitive effect of vegetative resprouts on seedlings or seedlings on vegetative resprouts throughout the experiment.

  5. Each of the three means of regeneration has its unique role in the maintenance of species diversity during gap colonization, and the importance of these roles differs in different functional groups.