不同生态恢复阶段无瓣海桑人工林湿地中大型底栖动物群落的演替

对广东省珠海市淇澳岛红树林自然保护区恢复背景相同的6个月林龄、3a林龄、6a林龄无瓣海桑人工林和光滩湿地中的大型底栖动物群落进行了比较研究。结果显示:处于不同生态恢复阶段的无瓣海桑人工林林地中大型底栖动物优势种(Y>0.02)存在差异;相似性分析检验(One-Way ANOSIM)表明4种生境间大型底栖动物群落结构差异显著。等级聚类和非参数多变量标序也显示4种生境间的大型底栖动物群落结构差异显著。相似性百分比分析(SIMPER)显示,各生境动物群落主要特征及群落间的差异主要是受各生境大型底栖动物优势种所决定。研究结果还表明:光滩、6个月林龄、3a林龄无瓣海桑人工林湿地中大型底栖动物群落的Shannon-Wiener多样性指数、Pielou均匀度指数和Margalef丰富度指数呈上升趋势,这说明无瓣海桑种植的前3a,随着植被的迅速恢复,大型底栖动物多样性增加明显。BIOENV分析结果表明:3a林龄之前的无瓣海桑人工林湿地中,大型底栖动物物种多样性主要受植被特征的影响,快速恢复的植被提供了荫蔽,既减轻了高温和水分蒸发对大型底栖动物的胁迫,又给动物提供了一个躲藏和逃避敌害的场所。而相对于植被的快速恢复,无瓣海桑人工林林地土壤理化性质的改变要缓慢和滞后得多。但随着恢复时间的延长,6a林龄无瓣海桑人工林湿地中的大型底栖动物群落的上述3个物种多样性指数反而明显下降。这是由于6a林龄无瓣海桑人工林林地土壤已具有红树林酸性硫酸盐土的基本特征,林地土壤理化性质的显著变化影响了大型底栖动物群落,还可能与无瓣海桑提供了和乡土红树植物不同营养水平(如C/N比)和单宁含量的"凋零物"食物源有关,具体机制还需进一步研究。

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

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.