Explaining species distributions by traits of bryophytes and vascular plants in a patchy landscape

Abstract

The species pool theory helps us understand species distributions at different geographical scales. In theory, species pools consist of species passing the filters between different geographical scales. Filters of dispersal and environment act between the regional and local pools, while filters of biotic interactions act between the local and the community pools. We studied bryophytes and vascular plants restricted to rich (calcareous) fens that occur as patches in a forested landscape. We then examined their frequencies and abundances at the local and regional scales and related the results to traits important for dispersal and competition. Our results show that weft-forming bryophytes and vascular plants with far-creeping rhizomes have higher local frequency than predicted from their regional frequency. Dispersal traits did not explain any variation in the distributions. This indicates that environmental and biotic filters are more important than dispersal limitation at the regional scale, and that clonal expansion is the most important factor for high frequency and abundance at the local scale in these nutrient poor habitats.