Nitrogen addition and rhizome severing modify clonal growth and reproductive modes of Leymus chinensis population

We examined the effects of N addition and rhizome severing on sexual and clonal reproduction and their trade-off in a rhizome clonal grass, Leymus chinensis (Trin.) Tzvel. We discovered that N addition not only greatly increased the quantity and biomass of Leymus chinensis ramets, but also promoted ramet production by increasing the tillers of the plant, while abated the other alternative clonal propagation strategy of rhizome elongation. However, N addition did not affect the rhizome biomass and it significantly reduced the flowering probability, the individual seed mass, and the seed number. Rhizome severing did not markedly affect the quantity and the weight of ramets, the individual seed mass or the seed number, but greatly decreased the rhizome biomass. A significantly negative relation was found between sexual and clonal propagation in Leymus chinensis population upon N addition. We showed that the nutrient availability can modify the sexual versus clonal reproductive trade-off and the clonal propagation strategy. Intense ramet production characteristics of clonal growth will largely affect the sexual reproductive capacity and intensify intraclonal competition, thereby influencing their genetic diversity, spatial colonizing ability and life history strategy.