Molecular characterization of long-term impacts of macrophytes harvest management in constructed wetlands.

There is little understanding of constructed wetlands (CWs) microbial community patterns in response to harvest management. Therefore, long-term impacts of harvesting Phragmites australis (Cav.) Trin. ex Steudel annually in November on the activity and community structure of microorganisms critical to the treatment efficiency of CW are elucidated. Findings show exponential increases in P. australis density and biomass with continuous harvesting, up to three times over unharvested CW. High-throughput pyrosequencing analysis demonstrates that plants harvesting improves the microbial community diversity and richness significantly, and more particularly, the relative abundance of Flavobacterium, Paenisporosarcina, and Povalibacter, which are extensively associated with CW performance. Consequently, increased plants biomass resulted in enhanced plants nutrients uptake in harvested (56.5 g N/m2, 5.5 g P/m2) than unharvested CWs (17.5 g N/m2, 1.8 g P/m2), whereas improved rhizosphere microclimates significantly enhanced nutrients removals in harvested CW (TN 109.9 g/m2 vs 67.4 g/m2, TP 18.0 g/m2 vs 13.0 g/m2).