Nutrient removal and plant biomass of 5 wetland plant species in Singapore

Five native plant species (Typha angustifolia, Scirpus mucronatus, Lepironia articulata, Eleocharis dulcis and Phragmites karka) were investigated for their nutrient removal efficiencies in shallow pond systems in Sg Buloh Wetland Reserve with water depth 0.12-0.30 m of a total 160 m² in area size. The project aimed to investigate nutrient removal rates, removal efficiencies, nutrient storage in plant biomass, and plant growth. Pond water quality before and after planting in fully vegetated ponds improved significantly at 24.4% TP and 64.4% TN reduction in Pond 6. Scirpus mucronatus, Typha angustifolia, Lepironia articulata and Eleocharis dulcis showed high growth rates. Phragmites karka showed low growth rate due to pest attack by aphids. Nutrient concentration in stem/leaf samples of the 5 species were within the ranges of 1% to 3% of dry weight for nitrogen and 0.1% to 0.3% of dry weight for phosphorus. Average daily mass removal rates ranged from 3.5-9.6 kg P ha⁻¹ day⁻¹ and 13.5-33.5 kg N ha⁻¹ day⁻¹. This field trial showed that the 4 species Lepironia articulata, Eleocharis dulcis, Typha angustifolia and Scirpus mucronatus are suitable species in surface flow wetland or shallow pond systems for nutrient removal in tropical environments.