Genotypic diversity and genotype identity of resident species drive community composition

Aims Species-rich plant communities are more resistant to invasions. In the past decade it was demonstrated that genetic variation also has many ecological effects. In our study we aimed to test whether the patterns of response to the genetic diversity of a resident species differ between colonizing species of different growth forms and whether the response is affected by soil nutrients. Methods We established experimental stands of a common grass, Festuca rubra, harbouring three levels of genetic diversity (1, 6 or 18 clonal genotypes, referred to as genotypic diversity) under two soil nutrient levels. In the fourth year after the stands were established, we sowed a mixture of four colonizers into the stands: a stoloniferous legume (Trifolium repens), a broad-leaf tussock grass (Anthoxanthum odoratum), a large-rosette forb (Plantago lanceolata) and a small-rosette forb (Campanula rotundifolia). We observed species establishment and growth over 3 years. We tested whether colonization success depended on genotypic diversity, specific Festuca genotypes, soil nutrients and colonizer growth form. Important Findings The colonization success and biomass of the colonizers were significantly affected by the genotypic diversity and the genotype identity of the resident clonal grass. The response, however, differed between the colonizers. The strongest response to the genotypic diversity of the resident species was observed in the tussock grass with a growth form and architecture similar to the resident species. The large-rosette species responded in early stages of growth whereas the stoloniferous legume did not respond at all. The intraspecific genotypic diversity and genotype identity of the resident species play an important role in the assembly of plant communities.