北部湾大风江与南流江河口红树林空间分布格局研究

Spatial patterns of the mangrove along the riverine estuaries, NanliujiangRiver and Dafengjiang River of the Beibu Gulf

生长在潮间带的红树植物在河口植物群落构成、海岸防风消浪中具有重要价值。本文基于本地种桐花树胚胎浸泡下沉实验与北部湾南流江和大风江河口段水体盐度、沿线潮间带植物群落结构与地貌分析,探讨红树林在河口空间分布及影响因素。结果主要表明:南流江河口和大风江河口红树林自海向陆基本展现“红树林纯林(桐花树、秋茄、无瓣海桑种类混生)→红树植物与半红树植物(黄槿、苦朗等)混生→红树植物、半红树植物与非红树植物混生→红树植物镶嵌→稀疏红树林小苗”的分布格局,但大风江河口向陆界限主要以红树、红树幼苗及半红树混生为主。此外,红树被浸淹时长是控制河口红树空间分布结构的主要因素。潮水上溯时长影响红树向陆生长的极限位置,宜林滩地是红树发育生长的必要条件。

Mangrove growing on the tidal flat is of important value for the estuarine plant community compositions and coastal protection against wind and wave.This study aims to explore the spatial distribution pattern and associated influencing factors of estuarine mangrove based on the soaking and sinking experiment of aboriginal Aegiceras corniculatum embryo and observations on water salinity,plant community structure and geomorphology of the tidal flat along the estuaries of Nanliujiang River and Dafengjiang River.Our results show that the distribution pattern of mangrove along Nanliuujiang River and Dafengujiang River estuaries exhibits a mode of“pure mangrove(e.g.mixture of Aegiceras corniculatum,Kandelia candel,Sonneratia apetala)→mixture of mangrove and semimangrove(Hibiscus tiliaceus,Clerodendrum inerme Gaertn)→mixture of mangrove,semi-mangrove and non-mangrove→mangrove mosaic→sparse mangrove seedlings”from sea to land.However,mangrove at the landward limitation of the Dafeng River estuary is characterized by a mixture of mangrove,mangrove seedlings and semi-mangrove.Besides,the time length of mangrove socking dominates the spatial distribution pattern of the estuarine mangrove while the time length of landward transport of tidal current affects the extreme location of the mangrove landward growth.A suitable tidal flat is an essential condition for the mangrove development and growth.