赤水桫椤群落乔木层优势物种生态位与种间联结性研究

摘要

Chishui Alsophila National Nature Reserve regards Alsophila spinulosa as the protective object.According to the field investigation of A.spinulosa community in the reserve,methods including niche breadth,niche overlap,variance ratio,chi-square test and association coefficient(AC)based on 2×2 contingency table were used for analyzing the interaction between the species population.The results show that:(1)Phyllostachys heterocycla has the largest niche breadth,followed by A.spinulosa and Mallotus barbatus.(2)The niche overlap of Pinus massoniana and Vernicia fordii,Cunninghamia lanceolata,Musa basjoo and Melliodendron xylocarpum are larger than that of other populations.(3)The overall correlations of 14 dominant species in tree layers showed non-significant negative correlation.The chi-square test showed that the association between A.spinulosa and other populations was not significant.Only a few species pairs of the community had a significant association,90.10% of species pairs did not reach a significant level.Most of the AC,OI,JI values are not high,the correlations between species pairs are weak,and species are relatively strong independence.The negative association of the community was more than positive association,and the community is in the unstable stage of dynamic succession.(4)The analysis of the relationship between the association of species and the corresponding niche overlap showed that there was a positive correlation between them.The stronger the interspecific association,the greater the niche overlap.The stronger the negative association,the smaller the niche overlap.%赤水桫椤国家级自然保护区是以桫椤为保护对象的自然保护区,该研究在对保护区桫椤(Alsophila spinulosa)群落进行野外调查的基础上,采用生态位宽度、生态位重叠和基于2×2联列表的方差比率法(VR)、卡方(χ2)检验、联结系数(AC)等方法,分析了群落物种间的相互关系.结果表明:(1)研究区内毛竹(Phyllostachys heterocycla)的生态位宽度最大,其次是桫椤和毛桐(Mallotus barbatus).(2)马尾松(Pinus massoniana)与油桐(Vernicia fordii)、杉木(Cunninghamia lanceolata),芭蕉(Musa basjoo)与陀螺果(Melliodendron xylocarpum)的生态位重叠值较大.(3)14个乔木层优势物种间总体关联性呈不显著负相关关系;卡方检验表明桫椤与其他种群之间联结性均不显著,群落中90.10%种对的联结性均未达到显著水平,只有极少数种对存在显著关联;大部分种对的AC、Ochai指数(OI)、Jaccard指数(JI)值都不高,种对间相关性较弱,独立性相对较强,且群落负联结的种对多于正联结,处于动态演替不稳定阶段.(4)物种之间的联结性与相应的生态位重叠结合分析表明,两者呈正相关关系,表现为种间正联结越强,生态位重叠越大,负联结越强,生态位重叠越小.