华润楠Machilus chinensis是广东南澳岛南亚热带常绿阔叶林的重要代表物种,其群落生境受到不同程度的破坏,生态系统比较脆弱,保护和恢复其群落变得越来越紧迫.种间联结研究有助于正确认识群落结构和演替趋势,对植物群落的保护和恢复具有重要意义.为全面了解脆弱生境下南澳岛华润楠群落种间联结特性,在华润楠次生林群落调查的基础上,采用2×2联列表,通过方差比率(VR)、x2检验、联结系数AC、共同出现百分数PC的计算及DCA排序,对华润楠群落乔木层中重要值较高的12个主要树种、66个种对间的关联性进行定量分析和生态种组的划分.结果表明:12个主要树种间总体关联性表现为不显著负联结,反映了该群落处于动态演替过程中,尚未达到稳定状态.与华润楠群落12个主要树种以喜光树种为主,建群种华润楠和台湾相思分别处于进展演替和衰退阶段等种群不稳定状态相符.x2检验与联结系数测定的结果基本一致,x2检验中表现为正联结的有31对,负联结的有33对,无联结的有2对,正负联结的比例较高,无联结的比例较低(占3.03％),群落向地带顶级演替仍然是一个相当漫长的过程.负联结中显著和极显著的种对较正联结的多,进一步反映了总体的负联结性.大部分种对的联结没有达到显著程度,种间联结较为松散,物种分布具有一定的独立性.根据群落12个主要树种的DCA排序和种间联结关系划分了3个生态种组.第Ⅰ生态种组为阳性先锋型,第Ⅱ生态种组为阳性喜温湿型,第Ⅲ生态种组为阳性中生演替型.生态种组的划分基本反映出了华润楠群落的演替序列和方向,群落由第Ⅰ、Ⅱ生态种组的喜光照、喜温湿类型向第Ⅲ生态种组的阳性中生演替型发展,并将逐渐恢复成为中生性和耐荫树种占主导的南亚热带常绿阔叶林.%Machilus chinensis is an important representative species of southern subtropical evergreen broad-leaved forests on the Island of Nan ao, Guangdong province. The Machilus chinensis communities have been suffered from serious damages due to human disturbance, which resulted in fragility and degradation in the structure and function of the ecosystems. Thus, it is an important and urgent task to find out the ways to protect and restore the communities. The inter-specific association, describing the interaction and relationship among the species in a plant community, has been widely employed in protection and restoration of plant communities. For better understanding about the characteristics of inter-specific associations about the M. chinensis communities in fragile environment, the inter-specific associations of a M chinensis secondary forest community on the Island of Nan'ao (abbreviated. As MCIN) were examined. A total of 28 sample plots was set up and investigated in the studied site. Based on the importance values, 12 main tree species were selected and 66 species-pair variables representing inter-specific associations in the communities were quantitatively analyzed using a set of methods, including variance ratio (VR) analysis, x2 test, association coefficient (AC), percentage of co-occurrence and de-trended correspondence analysis (DCA) based on 2×2 contingency tables of species presence/absence and abundance/quadrat data. The results show that 1) In general, there were significantly negative correlations among the 12 main tree species, which suggested that the community was in an unstable state, and it was still in the process of dynamic succession. It matches the actual state that the 12 main tree species in M. chinensis communities are dominated by intolerant tree species, the constructive species M. chinensis and Acacia confuse are respectively in progressive succession and decline stage of unstable state. 2) The similar results were obtainedthrough the x2 test and the AC test among these 12 main tree species. The x2 test indicated that there were 31 species-pair positive, 33 species-pair negative and 2 species-pair zero associations in the community, respectively. The proportion of positive and negative associations was higher and the zero associations was lower (account for 3%), which indicate that the community will take a long time to become a zonal climax vegetation type. The amount of species-pair with negative associations at the significant and highly significant level was higher than that with positive associations, which further demonstrated the negative correlations among the 12 main tree species. Most of the total 66 species-pair did not show significant associations, which indicated these plant species had relatively loose relationships, and they were independently distributed in the studied area. 3) According to the de-trended correspondence analysis (DCA) and their inter-specific relationships, the 12 dominant tree species were divided into three ecological species groups: Group Ⅰ , the intolerant pioneer tree species; Group Ⅱ , the intolerant tree species which like the warm and moist environment; Group Ⅲ the sunny meso-humid transitional species. The division of ecological species groups basically reflects succession series and direction of the M. chinensis communities. The communities develop from Group I and Group II to the Group Ⅲ, and it will gradually recover to south subtropical evergreen broad leaved forest, which is dominant of shade-tolerant mesophytic species.
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