The impact of different Spartina alterniflora eradication strategies on the biological community

The global invasive species, Spartina alterniflora has caused significant damage to coastal wetland ecosystems in China. This study evaluated the effectiveness and ecological impacts of two S. alterniflora management strategies in the Yangtze River estuary: Haloxyfop-R-methyl application and repeated mowing (once at the early flowering stage and once nine weeks later). The effectiveness of S. alterniflora control, and macrobenthos and bacterial community responses were compared at the Haloxyfop-R-methyl site, repeated mowing site, a control site, and a mud site during 2022–2023, and sediment physicochemical properties were also assessed. One year after Haloxyfop-R-methyl application, the density, aboveground biomass, height, and regenerated S. alterniflora were significantly reduced by 84 %, 94 %, 80 %, and 99 %, respectively. Mowing reduced the density, aboveground biomass, and height by 28 %, 78 %, and 29 %, respectively. At the Haloxyfop-R-methyl site, the biomass and Chao1 index of macrobenthos were significantly decreased compared with the control. There were significant differences in the macrobenthos community structure between the Haloxyfop-R-methyl and mowing sites compared to the control. Haloxyfop-R-methyl application and mowing did not significantly alter the α-diversity of bacterial communities but had an impact on the bacterial community structure, with the main indicator species differing among sites. Vegetation changes, sediment moisture content, total organic carbon content, and ammonium nitrogen concentration were the main factors influencing the composition of macrobenthos and bacterial communities at all sites. In summary, the Haloxyfop-R-methyl strategy better controlled S. alterniflora in coastal wetlands, while the repeated mowing strategy resulted in less disturbance of the major biological groups.