Plastic responses of invasive Bidens frondosa to water and nitrogen addition.
Invasive species are hypothesized to be more plastic than co-occurring native congeners, and variation in plasticity among invasive populations is predicted to facilitate invasion of new habitats. To explore the invasive ability of Bidens frondosa, we compared the plastic responses to water and nitrogen addition of the invasive B. frondosa in China with the co-occurring native congener B. tripartita, as well as among B. frondosa populations. The invasive plant performed better and showed higher phenotypic plasticity to water and nitrogen addition than the native. In addition, variations in performance and phenotypic plasticity were observed among the invasive populations. The biomass of the HN (Henan province) population increased more than that of other populations in response to nitrogen addition. The specific leaf area (SLA) of the GX (Guangxi province) population increased, while the SLA of the HN population decreased, and the HB (Hebei province) and EZ (Hubei province) populations showed no change in response to nitrogen addition. The observed higher phenotypic plasticity of B. frondosa relative to B. tripartita, and the observed variation in plasticity among B. frondosa populations may explain the invasiveness of this species. Predicted future increases in precipitation and atmospheric N deposition may further increase the invasiveness of B. frondosa.