为了解华北地区落叶阔叶林不同层次优势种的生态位和种间联结性，以北京四座楼市级自然保护区内的落叶阔叶林为研究对象，基于1 hm²样地调查数据，采用生态位宽度、生态位重叠，χ²检验、联结系数、Spearman秩相关系数和M. Godron稳定性指数分析各层次优势种的生态位和种间联结特征以及群落稳定性。结果表明：乔木层中，蒙古栎(Quercus mongolica Fisch. ex Ledeb.)的相对频度、重要值和生态位宽度均最大，蒙古栎-山杨(Populus davidiana Dode)的生态位重叠程度最高；灌木层中，小花溲疏(Deutzia parviflora Bunge)的重要值最大但相对频度和生态位宽度较小，相对频度和生态位宽度最大的为三裂绣线菊(Spiraea trilobata Linn.)；草本层中，重要值和生态位宽度最大的为糙苏〔Phlomoides umbrosa (Turcz.) Kamelin et Makhm.〕。乔木层、灌木层和草本层分别有4、34和30个种对Pianka指数大于0.5，生态位重叠程度较高。χ²检验和联结系数分析结果显示：乔木层、灌木层和草本层优势种形成的种对中正负联结比分别为0.7、1.5和5.0，但2种分析得出的显著性程度略有差异。Spearman秩相关性分析结果显示：乔木层、灌木层和草本层优势种形成的种对中正负联结比分别为0.9、1.6和4.9。乔木层总体联结性为不显著负联结，灌木层和草本层总体联结性均为显著正联结。M. Godron稳定性分析结果显示：各层次群落均处于较稳定状态，其中乔木层稳定性最高，灌木层稳定性最低。综合分析表明：乔木层大部分种对呈不显著联结，种间存在一定的竞争关系，但种间联结性较弱，群落稳定性高；灌木层和草本层正联结种对占多数，草本层种对正负联结比更高，种间相互促进，群落较为稳定。

To understand the niche and interspecific associations of dominant species in different layers of deciduous broad-leaved forest of north China, the deciduous broad-leaved forest of Sizuolou Municipal Nature Reserve in Beijing was taken as the research object, and the niche and interspecific association characteristics of dominant species in different layers as well as community stability were analyzed by using niche breadth, niche overlap, χ² test, association coefficient, Spearman’s rank correlation coefficient, and M. Godron stability index based on the survey data from 1 hm² plot. The results show that in the tree layer, the relative frequency, importance value, and niche breadth of Quercus mongolica Fisch. ex Ledeb. are all the largest, while the niche overlap degree of Q. mongolica-Populus davidiana Dode is the highest; in the shrub layer, the importance value of Deutzia parviflora Bunge is the largest but its relative frequency and niche breadth are relatively small, while the relative frequency and niche breadth of Spiraea trilobata Linn. are the largest; in the herb layer, the importance value and niche breadth of Phlomoides umbrosa (Turcz.) Kamelin et Makhm. are both the largest. The tree, shrub, and herb layers contain 4, 34, and 30 species pairs with Pianka index larger than 0.5, respectively, indicating relatively high niche overlap degree. The χ² test and association coefficient analysis results reveal that the positive to negative association ratios of dominant species pairs in tree, shrub, and herb layers are 0.7, 1.5, and 5.0, respectively, but the significance levels differ slightly between the two analyses. The Spearman^,s rank correlation analysis result shows that the positive to negative association ratios of dominant species pairs in tree, shrub, and herb layers are 0.9, 1.6, and 4.9, respectively. The overall association in the tree layer is non-significant negative association, but those in shrub and herb layers are both significant positive associations. The M. Godron stability analysis result indicates that communities in all layers are in a relatively stable state, with the tree layer being the highest stable and the shrub layer being the lowest stable. The comprehensive analysis suggests that most species pairs in the tree layer show nonsignificant associations, and there are some interspecific competition, but the interspecific associations are relatively weak and the community stability is high; the shrub and herb layers are dominated in species pairs with positive associations, and the positive to negative association ratio of herb layer is higher, suggesting interspecific mutual facilitation and relatively stable communities.