广西沿海不同演替阶段红树群落沉积物粒度分布特征

Characteristics of sediment grain size distribution of mangrove communities at different successional stages along the Coast of Guangxi

沉积物粒度分布是影响红树群落演替的重要因素之一。本文对代表广西红树群落演替趋势的白骨壤(Avicennia marina)、秋茄(Kandelia candel)、木榄(Bruguiera gymnorrhiza)3种红树群落沉积物进行了粒度分析。结果表明:3种红树群落沉积物类型均以砂和粉砂为主,随着红树林群落保存状况的逐渐变差,砂的含量逐渐上升,粉砂和黏土含量逐渐下降;沉积物粒径分布趋势均为砂>粉砂>黏土>砾。木榄和秋茄2个群落底床沉积物不同深度沉积物粒径分布规律一致,但与白骨壤群落存在差异;3种红树群落的沉积物粒度频率曲线均呈现为双峰或多峰形态。

Grain size of sediment plays a critical role in mangrove community succession. In this paper, the grain sizes of sediment of mangrove communities at three typical main successional stages （Avicennia marina, Kandelia candel, Bruguiera gymnorrhiza） along the coast of Guangxi were analyzed. The results showed that the sediment of the three mangrove communities was mainly composed of sand and silt. The content of sand increased and the content of silt and clay decreased gradually in the sediments of mangroves with growth condition getting worse. The content of grains in the sediment was as follows： sand〉 silt〉 clay〉 gravel. K. candel and B. gymnorrhiza communities had the same characteristics in vertical distributions of sediment grains, but differing from A. marina community. The frequencies of grain size in the sediments of the three mangrove communities were plotted and presented a bimodal or multimodal curve.