Assessing the nitrogen and phosphorus retention function of herbaceous communities in the water-level fluctuation zone of Songhua lake for mitigating eutrophication risk

The ecological health of water-level fluctuation zones is vital for maintaining the stability and function of aquatic and surrounding ecosystems. We investigated herbaceous plant community composition and the capacity to retain nitrogen (N) and phosphorus (P) across different shoreline areas (near-shore, middle-shore, far-shore) of Songhua Lake’s fluctuating zone. Carex rhynchophysa (near-shore), Setaria viridis (middle-shore), and Carex maximowiczii (far-shore) showed relatively high dominance and importance, and Artemisia integrifolia (middle-shore) only exhibited a high importance value. The vegetation showed biological enrichment coefficients for N that were all significantly greater than 1, while only Echinochloa crus-galli and Setaria viridis had coefficients for P greater than 1. Overall, Oxybasis glauca, Artemisia integrifolia, and Cirsium spicatum accumulated relatively high levels of both N and P. In contrast, Medicago sativa, Carex neurocarpa, and Artemisia sieversiana were more efficient at enriching N specifically. Notably, Carex rhynchophysa, Setaria viridis, and Carex maximowiczii exhibited better translocation of both N and P to aboveground tissues. Virtual artificial cultivation analysis showed that Oxybasis glauca, Artemisia integrifolia, and Cirsium spicatum exhibit the best N and P retention capabilities. Thus, herbaceous plant regulation represents a practical strategy for eutrophication control in water-level fluctuation zones.