In wetland ecosystems, macrophytes are sensitive to water level fluctuations. However, studies specific to the effects of water level fluctuations on distribution and composition of macrophytes are limited in sub-tropical floodplain wetlands of Nepal. This study aimed to examine the association between macrophytes and water levels in the floodplain wetlands of Koshi Tappu, in south-eastern Nepal. Sixty-four samples of macrophyte, along with twelve water quality parameters, five soil parameters and weekly water level information were collected from four shallow wetlands during summer, autumn, winter and spring over 2018 and 2019. Altogether, 52 macrophyte species belonging to 25 families were documented. Of them, 15, 6, 5 and 26 were emergent, submerged, floating and amphibian species, respectively. 10 species (5 emergent, 2 submerged, 2 floating and 1 amphibian species) were common across seasons. Regression analysis showed the decreasing trend in diversity, richness and evenness with increased water levels while at the same time overall macrophyte biomass increased. During summer, high water level supported the growth of floating invasive macrophytes, while medium and low water level during autumn and winter, respectively, supported submerged macrophytes. However, low-water level during spring supported emergent and amphibian macrophyte species. Canonical correspondence analysis (CCA) indicated that water depth and physico-chemical parameters such as water temperature, dissolved oxygen, pH, conductivity, nitrate-nitrogen, and phosphate were highly correlated with macrophyte assemblages across the wetlands. The study elucidated that management of water levels can ensure ecological integrity of wetlands and hence maintain biodiversity, and provide key indicators of water quality change.

在湿地生态系统中，大型植物对水位波动很敏感。然而，关于水位波动对大型植物分布和组成影响的研究仅限于尼泊尔亚热带洪泛平原湿地。本研究旨在研究尼泊尔东南部 Koshi Tappu 漫滩湿地中大型植物与水位之间的关联。2018 年和 2019 年夏、秋、冬、春季四个浅湿地收集了 64 个大型植物样本，以及 12 个水质参数、5 个土壤参数和每周水位信息。 总共 52 个大型植物物种，属于 25 科被记录在案。其中，15、6、5和26种分别为挺水、沉水、漂浮和两栖类。10 种（5 个挺水，2 个沉水，2 种漂浮和 1 种两栖动物）跨季节很常见。回归分析表明，随着水位的增加，多样性、丰富度和均匀度呈下降趋势，同时整体大型植物生物量增加。夏季，高水位支持漂浮的入侵植物生长，而秋季和冬季的中低水位分别支持沉水植物。然而，春季的低水位支持了挺水和两栖大型植物物种。典型对应分析（CCA）表明，水深和水温、溶解氧、pH、电导率、硝酸盐-氮和磷酸盐等物理化学参数与整个湿地的大型植物组合高度相关。