Abstract:On the basis of a comprehensive survey of the artificial mixed forest of Cunninghamia lanceolata and Mytilaria laosensis in the Daqingshan Experimental Field in Guangxi, we selected a typical fixed plot of 90 m × 110 m by a typical method to measure the coordinates of the center of each standing tree. The scale of each plant is measured, includes the diameter, the height and the width of the tree. We analyzed the population dynamics of the mixed forests, the spatial distribution pattern of main woody plant populations and the interspecific association of main populations in order to explore the interactions between species in the artificial mixed forest of C. lanceolata and maintaining population stability and succession by using diameter class replace the age class and the Ripleys L(r) function of spatial point pattern. It provides a theoretical basis for tree species selection, spatial structure adjustment and tending management for subtropical mixed forests. The results showed that: (1) there were 49 species and 3 361 viable standing trees with a breast diameter of ≥1 cm in the plot, including the important values of seven species of C. lanceolata, Mytilaria laosensis, Evodia lepta, Castanopsis hystrix, Psychotria rubra, Ficus hispida, and Wendlandia uvariifolia. Of all are above 4%, which has a large advantage and is the main tree species of the forest. (2) All living stands (DBH≥1 cm) in the mixed forest of C. lancenlata and M. laosensis showed clustering distribution on the scale of 0-40 m, among which: saplings (1 cm≤DBH<5 cm) were on the scale of 0-40 m. The degree of aggregation is higher than that of all living trees in the community. Small trees (5 cm≤DBH<10 cm) are randomly distributed on the scale of 0-5 m, and the degree of aggregation is weak on the scale of 6-40 m, while large tree (DBH≥10 cm) exhibits a uniform distribution on a scale of less than 5 m and a random distribution on a scale of 5 to 40 m. (3) In addition to the random distribution of the seven old populations in the community, except for the M. laosensis and C. hystrix, the other populations are subject to aggregate distribution, and the degree of aggregation increases with the scale. (4) The large trees and the small trees in the plot are independent of each other, and there is a positive correlation between the small trees and the saplings, the large trees and the saplings in the research scale. (5) There is no correlation or negative correlation among the main populations (21 species pairs) in the study area, and only a small number of populations (5 pairs) are positively correlated, indicating that the stability of the structure of the artificial mixed forest of C. lanceolata and M. laosensis in the Daqingshan experimental field in Guangxi is weak, and it has not reached the top stage of community succession.