Keywords: 
• forest ecology /
• mixed conifer and broadleaf forest /
• dominant tree species /
• egyi competition index /
• competitive tree selection /
• Qingshan Lake

Abstract: To improve forest structure and forest landscape quality，tree intraspecific and interspecific competition characteristics of a conifer and broadleaf mixed forest，one of the main forest types of the Qingshan Lake Area，were studied. Methods included use of typical sampling laws to establish research plots with a survey of each measurement factor for species within the plots. The Hegyi competition index was used to analyze and to suggest improvements in defining dominant trees. Dominant trees were determined by judging the relationship of the crown to distance between dominant trees and objects. Regression analysis was also used. Results demonstrated that intraspecific competition of superior trees was greater than interspecific competition. Superior trees included Cunninghamia lanceolata，Castanopsis eyrei，Schoepfia jasminodora，and Schima superba. Strong competition was found between the Quercus fabri and Liquidambar formosana，Q. fabri and Castanopsis eyrei，and Platycarya strobilacea and Cunninghamia lanceolata. Regression analysis showed that competition intensity and tree diameter at breast height（DBH）had a significant（P ＜ 0.01）exponential relationship. Also，intraspecific and interspecific competition intensity of a dominant tree population decreased when tree DBH increased，remaining at low levels. Thus，strong competition between species showed that they had similar niche requirements with competition for resources on the environment being more intense.［Ch，2 fig. 4 tab. 9 ref.］