湖北七姊妹山亚热带常绿落叶阔叶混交林主要木本植物的生态位与种间联结

目的 探究亚热带常绿落叶阔叶混交林的生态位特征和种间联结,阐明主要木本植物种间关系及对环境适应状况,为亚热带地区生物资源保护和森林管理提供理论依据。 方法 本研究基于湖北七姊妹山国家级自然保护区6 hm2（300 m × 200 m）标准大样地数据,从物种组成、生态位宽度、生态位相似性系数、生态位重叠指数、方差比率法、χ2检验、联结系数、Jaccard指数等方面研究了16种主要木本植物（重要值大于1%）的生态位和种间联结。 结果 （1）2020年湖北七姊妹山亚热带常绿落叶阔叶混交林共有64科140属266种木本植物,主要有桦木科、壳斗科和金缕梅科等,物种组成逐渐复杂。（2）川陕鹅耳枥的物种重要值和生态位宽度最高,占据绝对优势地位,与其他主要木本植物之间具有较高的生态位重叠和生态位相似性。四照花、灯台树和尖叶四照花的优势地位次之。生态位重叠指数和生态位相似系数均以0.2～0.5之间为主,大部分物种对生境需求具有一定相似性、互补性。物种重要值排序与生态位宽度排序并不完全相同。（3）湖北七姊妹山亚热带常绿落叶阔叶混交林内物种间总体关联性呈现显著正联结,且正负联结比值大于1。16种主要木本植物的χ2检验、联结系数、Jaccard指数、Pearson相关系数和Spearman秩相关系数的结果基本一致：正关联种对数大于负关联种对数,极显著或显著正关联种对数比极显著或显著负关联种对数多,不显著关联种对数也占有重要比例。 结论 亚热带常绿落叶阔叶混交林物种丰富,群落处于演替早期至中期阶段,种间关系松散、不紧密。

Niche and Interspecific Association of Main Woody Plants in the Subtropical Evergreen-Deciduous Broadleaved Mixed Forest in Qizimei Mountain,Hubei Province

Objective The species niches characteristics and interspecific associations of the subtropical evergreen-deciduous broadleaved mixed forest were explored to clarify the interspecific relationship and environmental adaptation of main woody plants, and ultimately provide a theoretical basis for biological resource protection and forest management in subtropical regions. Method Based on 6 hm2 (300 m × 200 m) standard large sample plot data of Qizimei Mountain National Nature Reserve in Hubei Province, the niches and interspecific associations of 16 main woody plants (important value greater than 1%) were studied from species composition, niche breadth, niche similarity coefficient, niche overlap index, variance ratio method, χ2 test, association coefficient, and Jaccard index. Result (1) In 2020, there were 266 species of woody plants belonging to 140 genera and 64 families in the subtropical evergreen-deciduous broadleaved mixed forest in Qizimei Mountain, Hubei Province, mainly including Betulaceae, Fagaceae and Hamamelidaceae. The species composition tended to be more complex. (2) The species importance value and niche breadth of Carpinus fargesiana were the highest, occupying an absolute dominant position. There was a high niche overlap and niche similarity between C. fargesiana and other main woody plants. The dominant position of Carpinus fargesiana, Dendrobenthamia japonica var. chinensis and Dendrobenthamia angustata was second. Both the niche overlap index and the niche similarity coefficient were mainly between 0.2 and 0.5, and most species had certain similarity and complementarity to habitat requirements. In addition, species importance ranking was not exactly the same as niche breadth ranking. (3) The overall correlation between species in the subtropical evergreen-deciduous broadleaved mixed forest of the Qizimei Mountain, Hubei Province showed a significantly positive association, and the ratio of positive to negative association was greater than one. The results of χ2 test, association coefficient, Jaccard index, Pearson and Spearman correlation coefficient of 16 main woody plants were generally consistent. The number of positive associated species pairs was greater than that of negative associated species pairs, and the number of extremely significant or significant positive associated species pairs was more than that of extremely significant or significant negative associated species pairs. The number of non-significantly associated species pairs also accounted for an important proportion. Conclusion The subtropical evergreen-deciduous broadleaved mixed forest is rich in species. The community is in the early to middle stages of succession, and the interspecific association is loose and not close.