title: Symbiotic bacteria as a determinant of plant community structure and plant productivity in dune grassland.
abstract: Symbiotic interactions are thought to play a key role in ecosystems. Empirical evidence for the impact of symbiotic bacteria on plant communities is, however, extremely scarce because of experimental constraints. Here, in three complementary experiments, we show that nitrogen-fixing rhizobia bacteria act as a determinant of plant community structure and diversity. Grassland microcosms inoculated with a mixture of rhizobia had a higher above-ground plant productivity (+35%), contained more nitrogen (+85%) and had significant higher community evenness (+34%) than control microcosms without rhizobia. Moreover, three of the four studied legume species required rhizobia to successfully coexist with other plant species. In contrast, the growth and survival of three grass and five forb species were not affected by the presence or absence of rhizobia. Finally, our results also showed that the legume species largely relied on symbiotically fixed nitrogen, both in the field and in the microcosms. This indicates that results in the microcosms are indicative for processes occurring in the field. It is concluded that symbiotic interactions between plants and prokaryotes can contribute to plant productivity, plant community structure and acquisition of limiting resources in legume-rich grassland communities.
authors.affiliation: Institute of Ecological Sciences, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands.
authors.forename: Marcel G A
authors.initials: MG
authors.lastname: van der Heijden
authors.forename: Roy
authors.initials: R
authors.lastname: Bakker
authors.forename: Joost
authors.initials: J
authors.lastname: Verwaal
authors.forename: Tanja R
authors.initials: TR
authors.lastname: Scheublin
authors.forename: Matthy
authors.initials: M
authors.lastname: Rutten
authors.forename: Richard
authors.initials: R
authors.lastname: van Logtestijn
authors.forename: Christian
authors.initials: C
authors.lastname: Staehelin
mesh_terms: D019659:Asteraceae / Q000254:growth & development / Q000382:microbiology; D029748:Caryophyllaceae / Q000254:growth & development / Q000382:microbiology; D017753:Ecosystem; D007887:Fabaceae / Q000254:growth & development / Q000382:microbiology*; D031314:Geraniaceae / Q000254:growth & development / Q000382:microbiology; D019684:Magnoliopsida / Q000254:growth & development* / Q000382:microbiology; D009584:Nitrogen / Q000378:metabolism; D009586:Nitrogen Fixation; D010943:Plantago / Q000254:growth & development / Q000382:microbiology; D006109:Poaceae / Q000254:growth & development* / Q000382:microbiology; D012231:Rhizobium / Q000502:physiology*; D012987:Soil / Q000032:analysis; D012988:Soil Microbiology; D013559:Symbiosis
chemical_list: D012987:Soil; D009584:Nitrogen