雷州半岛徐闻红树林植物群落的结构和动态特征

为揭示不同潮位红树林群落结构及动态规律,本文对雷州半岛徐闻官曹红树林群落的物种组成、物种年龄结构和多样性等群落特征进行了分析.结果表明:离岸高潮位和和中潮位均为白骨壤+红海榄群落,低潮位为白骨壤群落,反映随潮位的降低,群落物种数逐渐减少,白骨壤种群在各潮位均为优势种,具较宽生态位,而次优势种群红海榄则只分布于中高潮位,生态位相对较窄.白骨壤和红海榄在所出现的潮位中,其幼苗和苗木均较多,年龄结构均属于增长型.各群落物种多样性Simpson指数(D)、Shannon(H)和Pielou均匀度指数(J)的大小顺序关系均为中潮位的白骨壤+红海榄群落＞高潮位的白骨壤+红海榄＞低潮位的白骨壤群落.隐含着高潮位物种竞争剧烈,均匀度较小,中潮位物种关系稳定,均匀度较大,低潮位物种受环境严重胁迫表现适生选择性.白骨壤和红海榄在所出现的潮位中,种群格局均属于集群分布,反映其典型的胎生红树特征.

Structure and Dynamic Succession on Mangrove Communities in Xuwen of Leizhou Peninsula

To clarify the trend in succession in mangrove communities that their population structures,the community characteristics of the mangrove communities from Guancao in Xuwen town,were studied,including:species composition,age structure and species diversity.Results showed that Avicennia marina + Rhizophora stylosa communities dominated in high tide and mid-extreme tide zones,whilst A.marina communities dominated in low tide zones.As the tide zone level decreased the balance of species changed from a balanced mixture to communities of almost pure A.marina in low tide zones,indicating that A.marina is adapted to a wider wide environmental niche compared to R.stylosa,which has a relatively narrow ecological niche and is confined tohigher tide zones.The order of Simpson's index (D),Shannon's index (H)and Pielou's evenness index (J) in each community was as follows:the community of A.marina + R.stylosa in mid-extreme tidal zones ＞ community of A.marina + R.stylosa in high tide zones ＞ community of A.marina in low tide zones,implying that mangrove species have fierce competition and small uniformity in high tide habitats,stable species relationship and larger uniformity in mid-extreme tide habitats and a different degree of adaptation to harsh environments in lower tide habitats.The population patterns of A.marina and R.stylosa have clustered distributions,their appearance in all tidal zones shows the typical viviparous features of mangrove.