中文摘要：

红楠（Machilusthunbergii）林是浙江沿海地区典型森林类型之一，研究竞争强度的动态变化规律及红楠种群的生态适应机制，对舟山群岛常绿阔叶林的保护与可持续利用具有重要意义。利用Hegyi单木竞争指数模型，对舟山桃花岛次生林优势种红楠的种内和种间竞争强度进行定量分析。结果表明：红楠3种类型的竞争强度均随对象木胸径的增大而逐渐减小，小径级的红楠承受的竞争压力较大；红楠的种内和种间竞争强度分别占总竞争强度的44．55％和55．45％，两者大致相等，说明其受到的种内和种间竞争压力均衡；落叶树种的平均竞争指数大，常绿树种的平均竞争指数小，使红楠受压的主要树种是朴树和枫香树；红楠种内和种间竞争强度的顺序为：红楠种内〉朴树〉枫香树〉椿叶花椒〉柘〉株木〉化香树〉赛山梅〉黄檀〉日本珊瑚树〉天仙果等；3种类型的竞争强度与对象木胸径均呈显著负相关，且服从幂函数关系CI=AD-B，当红楠胸径达到20cm以上时，竞争强度变化很小，利用所得的预测模型能很好地预测红楠种内和种间竞争强度。当红楠胸径小于20cm时，应对其进行抚育管理以提高红楠成活率和促进植被恢复。

英文摘要：

Machilus thunbergii forest is one of the typical forest type in coastal areas of Zhejiang. To protect and obtain sustainable utilization of evergreen broadleaved forest in Zhoushan islands, studying the rule of dynamic changes of competition intensities and the ecological adaptation mechanism of M. thunbergii is important and meaningful. By using Hegyi＇ s single-tree competition index model, the intraspecific and interspecific competition intensities of M. thunbergii, one of the dominant species in secondary forest of Taohua Island were quantitatively analyzed. Three types of competition intensity of M. thunbergii were decreased gradually with the increase of objective trees diameter, which showed a stronger competition at a smaller diameter. The intraspecific and interspecific competition intensity of M. thunbergii accounted for 44.55% and 55.45% in the total competition intensity, respectively. The intraspecific competition intensity in M. thunbergii and the interspecific competition intensity of accompanying species were approximately equal, which meant that the intraspecific and interspecific competition were in balance status. The average competition index of deciduous species were strong, while those of evergreen species were weak. The competition mainly came from two competitors： Celtis sinensis and Liquidambar formosana. The order of the intraspecific and interspecificcompetition intensity of M. thunbergii was： Machilus thunbergii 〉 Cehis sinensis 〉 Liquidambar formosana 〉 Zanthoxylum ailanthoides 〉 Maclura tricuspidata 〉 Comus macrophylla 〉 Platycarya strobilacea 〉 Styrax confusus 〉 Dalbergia hupeana 〉 Viburnum odoratissimum var. Awabuki 〉 Ficus erecta. There was a significantly negative correlation between three types of competition intensity and the DBH of objective trees. The relationship between the competition intensity and the DBH of objective trees followed the equation CI = AD-B. The change in competition intensity was very small when the DBH of M. thunbergii reached 20