[Structure and dynamics of co-dominant species in different succession stages of natural forests in Daxing'an Mountains, China].

Affected by the disturbance of forest fire and logging, the primary forest in Daxing'an Mountains gradually degenerates into secondary forest. In this study, we established 16 plots in each of three typical forests, including natural pure forest (pioneer stage), natural . and mixed forest (transition stage) and natural . pure forest (top stage). The methods of population age and tree height structure, static life table, survival analysis, dynamic index and time series prediction were used to quantitatively analyze the dynamics of dominant species (. and . ) and all the arbors, aiming to provide scientific basis for the restoration and development of natural . forest. The results showed that the abundance of young co-dominant species and total arbors in each stage was large, and that all population had strong self-renewal potential. With the progress of succession, the abundance of . in each age class gradually decreased, whereas that of . gradually increased. The mortality and disappearance rates of total arbors and . in the transition stage and . in the pioneer stage gradually increased with the increases of age class, and the survival curve was Deevey-Ⅰ type. The survival analysis results showed that the population was stable in the early stage, increased in the middle stage, and declined in the later stage. In other stages, the mortality rates fluctuated slightly, the survival curves were Deevey-Ⅱ type, and the population increased in the early stage, declined in the middle stage, and stable in the later stage. The co-dominant species and total arbors were growing in the three succession stages, among which . in the pioneer stage, . and total arbors in the top stage showed the lowest sensitivity to the environment. The results of time series prediction showed that the co-dominant species and total arbors in each stage would increase in the future. During forest succession, it was necessary to strengthen the protection of seedlings and young trees, thin the forest with large coverage, and take appropriate measures to ensure population renewal.