Responses of the invasive aquatic plant water hyacinth to altered nutrient levels under experimental warming in China

Abstract

Global warming and eutrophication may interact and increase the invasiveness of certain aquatic plants. To test this hypothesis, a mesocosm experiment was conducted to investigate the growth, biomass allocation and carbon/nitrogen balance of the invasive aquatic plant Eichhornia crassipes (Mart.) Solms in response to three nutrient levels representing oligotrophic to eutrophic water under simulated warming in a greenhouse. The growth and clonal propagation of E. crassipes were significantly promoted by simulated warming and elevated nutrient levels. The mean relative growth rate and mean clonal propagation rate of the plants increased 32% and 152% due to elevated nutrient levels, whereas those values increased 18.3% and 14.9% due to warming. The shoot/root ratio of E. crassipes was also greatly improved by simulated warming (50.2% increase) and elevated nutrient levels (475% increase). Moreover, the leaf and stembase N concentrations increased and C/N mass ratios decreased with elevated temperature and nutrient levels. These results suggest that the ecological invasion of the highly invasive aquatic plant E. crassipes will be exacerbated by increasing eutrophication under future climate warming in China.