Hydrological alteration induced changes on macrophyte community composition in sub-tropical floodplain wetlands of Nepal

• Published in: Aquatic botany Vol. 173; p. 103413
• Main Authors: Regmi, Tika, Shah, Deep Narayan, Doody, Tanya M., Cuddy, Susan M., Tachamo Shah, Ram Devi
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.07.2021
• Subjects: Aquatic plants; Eco-hydrology; Koshi tappu wildlife reserve; Physico-chemical parameters; Shallow Water zone; Shallow Water zone; Koshi tappu wildlife reserve; Physico-chemical parameters; Eco-hydrology; Aquatic plants
• ISSN: 0304-3770; 1879-1522
• DOI: 10.1016/j.aquabot.2021.103413

•Seasonal investigation of aquatic vegetation in sub-tropical floodplain wetlands in Nepal.•Seasonal changes in macrophyte community composition in Wildlife Reserve wetlands.•52 species from 25 families found in sub-tropical wetland during annual hydrological cycle.•Richness of amphibian macrophytes higher during low water level.•Physicochemistry and water level influence macrophyte distribution and composition. 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.