中文摘要：

【目的】韩江三角洲是我国沿海6大河口区域之一,在湿地生物多样性保护、生态安全保障方面具有重要意义。因此,对韩江三角洲现存红树林群落及立地条件进行全面研究,可以为当地的红树林保护与恢复工作提供依据。【方法】以样线调查、样方设置的方式采集韩江三角洲红树林群落现状和立地因子原始数据,使用多元统计方法进行群落综合评价。【结果】共记录真红树和半红树植物10科13种,其中4种为人工引种;与1964年的记录相比,本区域红树林种类变化不大,但天然植物种群普遍萎缩,木榄野外种群灭绝,天然林分布范围狭窄且呈破碎斑块状,约3/4面积的红树林已消失;本地区天然红树林植物区系与广东福田、福建漳江口和九龙江口的相似度高于与我国南部其他红树林区的相似度;红树林群落Shannon-Wiener多样性指数（H＇）为0.168~1.318,Pielou均匀度指数（J）为0.242～0.896,多数人工林群落H＇和J值较高,反映了人工造林树种搭配多样、均匀的特点;而天然林H＇和J值均较低,群落内桐花树占绝对优势,降低了其他物种的重要性;韩江三角洲红树林现存群落生物量最高值为莲下六合围人工林的106 233 kg獉hm-2,是生物量最低的濠江澳头天然林的14.9倍;各群落立地环境因子差异显著,沉积物盐度、土壤盐度与土壤电位指标的相关性较高,p H值则和各营养盐水平相关;土壤盐度、孔隙水盐度、土壤电位与红树林群落所处的地理位置有关,地处河口区域不同水平距离会影响立地盐分和滩涂高程;主成分分析结果显示,韩江三角洲的红树林群落立地条件差异较大,总体上盐分低、透气性好、养分充足的立地条件较好,其中位于淡水感潮河段的巷口村立地条件最优,其盐分较低,沉积物通气性较好且肥力充足,适合无瓣海桑和海桑等耐低盐生境的物种生长。【结论】建议实施和加强对?

英文摘要：

[ Objective ] As one of the six major estuaries in China, the Hanjiang River Delta （HRD） is of significant importance for conserving wetland biodiversity and guaranteeing ecological safety. Hence, conducting a detailed survey on the mangrove communities and their sites conditions in this area could provide a basis for mangrove conservation and restoration. [ Method] The current mangrove communities at the HRD were surveyed by means of route investigation and plot sampling to collect data of communities and site conditions. Multivariate statistical methods were performed for comprehensive evaluation of the communities. [ Result] Totally, 13 species of true mangrove and semi-mangrove plantswhich belonged to 10 families were recorded, including 4 introduced species. Compared with the records in 1964, the species composition was not changed significantly. However, the natural mangrove populations have declined generally, especially characterized by the extinction of natural population of Bruguiera gymnorrhiza. The natural mangroves were retreated, fragmented, and subjected to an area loss of almost three fourths. The flora similarities of mangrove between the HRD and Futian, Zhangjiang Estuary, Jiulongjiang Estuary were higher than those between the HRD and other mangroves of southern China. The species diversity as Shannon-Wiener index （H＇） ranged 0. 168 -1. 318, and evenness as Pielou evenness index （J） varied between 0. 242 - 0. 896. The H＇ and J indices of artificial mangroves were both higher than those of natural mangroves, indicating a more diversified and well-proportioned state in artificial mangroves. Oppositely, due to the massive dominant population of Aegiceras corniculatum, the natural mangrove communities had lower H＇ and J indices. The site of Liuhewei had the maximum value of biomass at 106 223 kg. hm-2, which was 14.9 times of the biomass value at the site of Aotou. The environmental factors were statistically significantly different among communities. Salinity and Eh value were si