Is the population turnover of patchy-distributed annuals determined by dormancy dynamics or dispersal processes?

In species with fragmented distribution, regional turnover dynamics is given by the processes of local population extinction and patch (re)colonization by migrants spreading from neighboring occupied patches. In plants with dormant stages (e.g. seeds) and limited dispersal capacity, regional dynamics based on dispersal processes can be overridden by pseudo-turnover determined by signals inducing or breaking dormancy (e.g. due to changes in habitat quality) resulting in a low importance of habitat configuration and size. In this study, I investigated the turnover dynamics of 5 annual plant species growing on ant mounds of Lasius flavus over three years. I analyzed whether the grassland-scale dynamics of these annuals is influenced by dispersal processes, or alternatively, by pseudo-turnover of soil seed populations. For that purpose I 1) searched for populations formed from soil seeds only, 2) compared the relative contribution of the soil seed bank and seed rain for population restoration after disappearance from the vegetation and 3) investigated whether colonization and extinction events are affected by patch isolation. I assumed if population turnover was rather a result of the soil seed bank dynamics then spatial effects would be hard to detect. In spite of the presence of populations formed from soil seed and the relatively more important soil seed bank for potential population reestablishment, turnover dynamics followed the predictions of metapopulation theory. Population appearance was more probable in larger and less isolated patches. Probability of disappearance increased with decrease of population size that was negatively influenced by the patch size and its isolation. These findings indicate dispersal processes to be important in the turnover dynamics and only limited contribution of soil seed populations. Their small effectiveness is probably related to the low chance of recurrent disturbance on the mound surface.