To present a guideline on the construction and management of artificial wetlands for high biomass production, three
emergent macrophytes (Phragmites australis, PA; Typha angustifolia, TA; and Zizania latifolia, ZL) were planted under two
substrates conditions (general soil with and without moss peat) and two water levels (5 cm and 20 cm) and monitored for
three years. ZL showed greater growth performance rather than the others not only at early growth phase in the first year
[shoot height, 200 cm; above-ground dry weight (AGDW), 500 g/m2] but also in the last year (ZL, 1,100 g/m2; TA, 770
g/m2; and PA, 450 g/m2 of AGDW). ZL with rapid growth at the early growth phase was not affected by naturally
introduced weeds, whereas slower and poorer growth of PA and TA at the early growth phase resulted in relatively higher
introduction and establishment of natural weeds. In turn, such introduced weeds negatively contributed to the growth of PA
and TA particularly under shallow water (5 cm) with the substrate condition including moss peat. We suggest a plant
material with rapid and great growth at the early phase such as ZL for reducing possible negative influences by the natural
weeds and wild animals for high biomass production in constructed wetlands. A pre-growing process in greenhouse prior to
planting might be an useful option to raise the competitiveness of those species when planting PA and/or TA. In addition,
we recommend that integrated weed management system with utilizing various options at the most appropriate timing must
be applied for maintaining sustainable high biomass production at the artificial wetlands.