The Impact of Plant Spatial Patterns on Nitrogen Removal in the Naolihe Wetlands of Northeast China

Abstract

The impact of the spatial pattern of wetland plants on nitrogen removal is a hot research topic. Ten water samples were collected from separate sampling points in mid-August and at the end of October 2021, and the concentrations of TN, NH4-N, and NO3-N in the water were measured to calculate the removal rates for the three forms of nitrogen in Naolihe wetlands. The spatial indices were interpreted for various plants based on images from samples taken in August. Step-by-step eliminations and function fitting methods were performed to determine the relationships between the spatial index and the removal rates for three forms of nitrogen. The results show that both Deyeuxia angustifolia (DA) and Phragmites australis (PA) ranked first for the functions between the order of sampling points of spatial indices (areas and shapes) and the removal rates for the three forms of nitrogen during the elimination process, indicating that DA and PA were the main forces determining nitrogen removal, which was dependent on plants covering the largest areas (DA: 31.2% and PA: 24.3%), with some large patches (largest plants index: DA (0.26) and PA (0.21)) and strong connectivity (patch edge density: DA (16.79) and PA (15.70)). These results have value for studying the relationship between spatial patterns and water purification functions.