Study On Community Structure Characteristics Of Different Succession Stages Of Broad-leaved Korean Pine Forest In Changbai Mountain

Broad-leaved Korean pine forest is a zonal climax community below 1100 m in changbai mountain area.Different types of secondary forest communities are formed due to disturbances such as harvesting and fire.In order to accelerate the recovery of secondary forest and the progress of secondary succession,and the community characteristics of each succession stage were mastered.Based on the original research,this paper took 854 sample plots in changbai mountain forest area as the research object,divided the succession sequence by the method of combining plant species and site.Quantitatively discussed the succession stage,and then study the community characteristics of different succession stages under each succession sequence.The main results are as follows:(1)According to the dominant species of the main layer of the community,and considering the site conditions,854 plots belonging to the broad-leaved Korean pine forest area were selected,among which 243 were xerophytic sequences,398 were mesophytic sequences and 213 were hygrophytic sequences.In the process of succession,the evolution of forest type of each succession sequence begins with the initial plant community composed of pioneer-positive tree species,and then the soft and hard mixed forest is transformed into the hard mixed forest,and finally reach the community of top broad-leaved Korean pine.(2)A total of 1024 species of plants were found in the study area,belonging to 401 genera of 97 families.There are 83 species of trees,belonging to 17 families and 35 genera;87 species of shrubs,belonging to 19 families and 33 genera;854 species of herb,belonging to 76 families and 338 genera.There were 937 species of hygrophytic sequences,belonging to 383 genera in 94 families.There were 580 species of xerophytic sequences,belonging to 77 families and 280 genera.There were 640 species of mesophytic sequences,belonging to 285 genera in 85 families.The composition of families and genera showed that the vegetation was concentrated in some cosmopolitan families,such as compositae,poaceae,ranunculaceae and rosaceae,with more oligopoly and monopoly.The composition of the genus shows that the vegetation is concentrated in some of the world's major families such as Compositae,Gramineae,Ranunculaceae,and Rosaceae,and there are many genus and single genus.(3)According to the replacement characteristics of the main tree species in the community,the succession process of each succession sequence can be divided into four stages,in which the succession value between 1-3 is classified as the early succession,characterized by a gradual decrease in the proportion of pioneer tree species.The succession value of 3-5 was classified as the mid prophase of succession,which was characterized by the increasing number of transitional species and their status in the community.The succession value is classified into 5-7 as the middle stage of succession.The main characteristics are that the transitional tree species and their dominant degree in the community gradually decline.The succession value ranged from 7 to 10,which was the late stage,and also reached the stage of typical broad-leaved Korean pine forest.(4)The total species richness of the community except the xerophytic sequences,the other two sequences reached the highest in the mid prophase or middle stage of succession;the species richness of the arbor layer in the three succession sequences reached the highest in the middle of succession;The difference in succession stage has a higher impact on the species richness of trees than other life forms and communities.The species richness of the xerophytic sequences was significantly lower than the other two sequences,and the difference in succession sequence had higher effects on the species richness of trees and shrubs than on herbs and communities.(5)The size class structure of all individuals(DBH?5cm)appeared a reverse "J" shape or quasi-inverted "J" shape in each successional sequence at each successional stage except that the 7-10 stage diameter structure of the xerophyte sequence is a unimodal type.The pioneer tree species diameter structure of each succession sequence is mostly unimodal in succession 1-3 and 3-5 stages;The transitional tree species in the succession 3-5 stage diameter structure are mostly inverted "J" type;The transitional tree species are mostly inverted "J" type in the 5-7 stage.The top species of Pinus koraiensis has an inverted "J" shape in the succession stage 5-7 and a unimodal type in the 7-10 stage.As the succession progresses,the diameter distribution shifts to the large diameter level.