Effects of different growth form submerged macrophyte assemblages on biomass accumulation and water purification

Abstract

种植水生植物，尤其是沉水植物，是目前广泛应用于受损水体的最主要的生态修复方法之一. 研究不同生长型沉水植物组合对水体理化因子的影响及营养物质的去除效率可为受损水生生态系统修复提供重要的科学依据. 本研究以我国水体修复中常用的3种不同生长型沉水植物苦草(Vallisneria natans)、黑藻(Hydrilla verticillata)和穗状狐尾藻(Myriophyllum spicatum)为研究对象，采用1种生长型种植和2种生长型及3种生长型混种模式，研究不同生长型沉水植物组合及其不同生长阶段对实验系统水质指标及氮、磷等营养物质去除率的影响. 结果表明，所有植物组合处理均显著提高了系统中总氮、总磷和氨氮去除率; 在实验前中期总氮、总磷和氨氮去除率最高. 从本实验受试物种组合来看，1种和2种生长型组合比3种生长型组合具有更高的生物量累积量和总氮去除率. Pearson相关性分析显示，实验系统中的pH、DO浓度与植物总生物量呈显著正相关，总氮、总磷、氨氮浓度均与植物总生物量呈显著负相关. 建议在受损浅水水生态系统修复过程中，根据生态修复不同阶段考虑不同生活型、生长型和功能群的水生植物组合; 在生态修复过程中需加强管理，如水生植物收割等，才能达到最好的修复效果.;Aquatic plants are important components of freshwater ecosystems and constitute a dominant actor in many shallow lakes. Planting aquatic plant, especially for submerged macrophytes, is one of the most important ecological restoration methods widely used in damaged shallow freshwater bodies. However, previously studies have mainly focused on the effects of macrophyte richness on biomass and water quality. Little is known about the effect of different assemblages with various growth form submerged macrophyte on biomass accumulation and water purification. In this study, three different growth form submerged plants, Vallisneria natans, Hydrilla verticillata and Myriophyllum spicatum, which are commonly used in water ecological restoration in China, were selected to test the effect of different growth form submerged macrophyte assemblages on water quality and nutrients removal rate. Our results showed that all different growth form assemblages have obvious purification effects on total nitrogen, total phosphorus and ammonia nitrogen, and higher purification effects were observed in the early and middle stage of the experiment. From different combinations, one and two growth form combinations have higher biomass accumulation and higher total nitrogen removal efficiency than three growth form combinations. Pearson correlation analysis showed that the pH, and DO in the experimental system were significantly positively correlated with the total biomass, and the concentrations of total nitrogen, total phosphorus and ammonia nitrogen were significantly negatively correlated with the total biomass. Our results suggest that in order to get the best restoration results, we need to take various factors into consideration during the process of ecological restoration, including different life form and growth form aquatic plant assemblages, harvesting aquatic macrophytes, etc.