Succession of macrofauna communities in wetlands of sonneratia apetala artificial mangroves during different ecological restoration stages

Abstract

The study was conducted to compare the differences of macrofauna communities of wetlands at 6-month, 3-year and 6-year forest age of Sonneratia apetala artificial mangroves whose restoration background had been the same and the naked tidal flat in Qi'ao Island Mangrove Nature Reserve of Zhuhai, Guangdong Province, China. The results showed that there were significant differences in dominant species of macrofauna (Y > 0. 02) in wetlands of S. apetala artificial mangroves during different ecological restoration stages. The analysis of One-way ANOSIM showed that there were significant structural differences in macrofauna communities in the four kinds of habitats. The analysis of hierarchical clustering and non-metric Multi-Dimensional Scaling also showed that the structure of macrofauna communities in the four habitats had significant differences. Similarity percentages analysis (SIMPER) showed that the main species which caused the differences of macrofauna communities in different habitats were the dominant species of macrofauna of each habitat. The results also showed that Shannon-Wiener diversity index, Pielou evenness index and Margalef richness index of macrofauna communities from the naked tidal flat, 6-month and 3-year forest age of S. apetala artificial mangroves were presented from low to high respectively, which indicated that macrofauna diversity had increased obviously with the rapid vegetation recovery in the first 3 years of S. apetala artificial mangroves. BIOENV analysis showed that the vegetation characteristics were the main reason which influenced the species diversity of macrofauna during the first 3-year forest age of the S. apetala artificial mangroves. The shade provided by the vegetation of rapid recovery may not only reduce the stress to macrofauna caused by high temperature and the moisture evaporation, but also provide a place for macrofauna to hide and escape predators. However, the change of soil physical and chemical properties of S. apetala artificial mangroves is slow and lagging compared with the rapid recovery of vegetation. However, with the elongation of recovery time,the macrofauna diversity index was significantly decreased at 6-year forest age of S. apetala artificial mangroves. This is due to the fact that the soil of 6-year forest age of S. apetala artificial mangroves already has the basic characteristics of acid sulfate soils of mangroves, and the physical and chemical properties of the soil which have been changed significantly has affected the macrofauna communities. It might also be caused by the different food sources (leaf-litters) provided by S. apetala, which have different nutrient levels (such as C/ N ratio) and tannin content, compared with indigenous mangrove plant. Specific mechanisms about them needs further study.