|Bremer, C; Braker, G; Matthies, D; Beierkuhnlein, C; Conrad, R: Plant presence and combination but not diversity influence the overall denitrifier function and the composition of nirK-type denitrifier communities in grassland soil, FEMS Microbiology Ecology, 70(3), 45-55 (2009)|
To explore potential links between plant communities, soil denitrifiers and denitrifier function, the impact of presence, diversity (i.e. species richness) and plant combination on nirK-type denitrifier community composition and on denitrifier activity was studied in artificial grassland plant assemblages over two consecutive years. Mesocosms containing 0, 4 and 8 species and different combinations of 2 species were set up. Differences in denitrifier community composition were analysed by canonical correspondence analyses following terminal restriction fragment length polymorphism (T-RFLP) analysis of PCR-amplified nirK gene fragments coding for the copper-containing nitrite reductase. As a measure for denitrifier function, denitrifier enzyme activity (DEA) was determined in the soil samples. Presence as well as combination of plants and sampling time but not plant diversity affected the composition of the nirK-type denitrifier community and denitrifier enzyme activity. Denitrifier activity significantly increased in the presence of plants especially when they were growing during summer and autumn. Overall, we found a strong and direct linkage of denitrifier community composition and functioning, but also that plants had additional effects on denitrifier function that could not be solely explained by their effects on nirK-type denitrifier community composition.