Ecological influence of exotic plants of Sonneratia apetala on understory macrofauna

The study aims to compare the differences of macrofauna communities of wetlands at 3-year-forest-age, 5-year-forest-age Sonneratia apetala artificial mangroves, 5-year-forest-age Kandelia candel artificial mangroves with the same restoration background, and the naked tidal flat in the Qi'ao Island Mangrove Nature Reserve of Zhuhai, Guangdong Province. The results show that there were significant structural differences in macrofauna communities among four kinds of habitats. The increase of biomass and species diversity of macrofauna at 3-year-forest-age S. apetala artificial mangroves was obviously faster than that at 5-year-forest-age K. candel artificial mangroves whose average tree height was close to that of 3-year-forest-age S. apetala artificial mangroves. The BIOENV analysis shows that it was related to the rapid growth of S. apetala, which rapidly changed the light level and shading conditions in the forests. The 5-year-forest-age S. apetala artificial mangroves had lower macrofauna species diversity but higher density and biomass than K. candel artificial mangroves with the same forest age. This was due to the rapid changes of physical and chemical properties of habitat soil by the ecological restoration of S. apetala artificial mangroves as well as the changed food sources possibly caused by the leaflitter of such non-indigenous mangrove species S. apetala. However, further survey should be conducted on whether there are any negative ecological impacts of largescale cultivation of S. apetala on macrofauna communities, so as to evaluate correctly S. apetala's role in the restoration of coastal mangrove ecosystems.