Abstract:

Understanding the species diversity of submerged plant communities in response to nitrogen and phosphorus nutrition levels in sediments can clarify the relationship between the two. This relationship has direct theoretical and practical significance for studying the spatial and temporal changes of wetland vegetation and environment, and has implications for habitat restoration, pollution control, and planning management in the study area and similar areas. In this study, the wetland areas (lakes and ditches) of Yinchuan Plain were used as the research area to conduct a field survey of the submerged plant communities to obtain an understanding of the environmental sediment nutrients. Three typical submerged plant communities were screened out by the community classification method, and the nitrogen and phosphorus nutrient levels of the wetland sediment were evaluated. A structural equation model was used to analyze the relationship between the species diversity of typical submerged plant communities and the nitrogen and phosphorus nutrient components of the sediments. The results revealed that eight common submerged plants exist in the wetlands of Yinchuan Plain. The typical submerged plant communities were identified as a Potamogeton pectinatus community, a Myriophyllum spicatum community, and a Potamogeton crispus community. The species composition diversity and species contribution of the Potamogeton crispus community were high, and the species distribution was uniform. The species in the Potamogeton pectinatus community showed cluster or patchy distribution. Three levels (rich, moderate, and poor) of nitrogen and phosphorus fertility were identified in the sediment of the wetlands of Yinchuan Plain, and moderate and poor levels of fertility were most commonly found. The Potamogeton pectinatus and Myriophyllum spicatum communities were found to grow mainly in the poor- and moderate-level fertility sediment areas, while the Potamogeton crispus community was found to grow in all three levels of sediment nutrient content. The nitrogen and phosphorus nutrition level of the sediment had a significant positive effect on the three typical submerged plant communities, promoting an increase in the community diversity index. The characteristics of the three typical submerged plant communities were mainly affected by species evenness. The nitrogen and phosphorus fertility level of the sediment was mainly affected by the phosphorus level in the sediment.

Key words: submerged plant community, sediment nutrient level, structural equation model, response