Objective Masson pine is a pioneer tree species for ecological restoration of degraded land in red soil erosion areas, and its population structure and dynamic characteristics are of great significance to the stability of regional ecosystems.

Methods Taking Masson pine plantations in typical red soil erosion control areas of Changting County, Fujian Province as the research object, based on comprehensive survey data of sample plots, a static life table was established by replacing time series with diameter class structure, survival curves were plotted, and the future development trend of the population was predicted by moving average time series method. At the same time, a diameter class-sample plot matrix was constructed, and redundancy analysis (RDA) was carried out in combination with environmental factors such as slope, slope position and disturbance intensity to quantitatively reveal the influence of environmental gradient on the diameter class structure differentiation of Masson pine.

Results (1) The diameter class structure of the Masson pine population is an irregular inverted "J" shape, with individuals mainly concentrated in the 2-5 age class. The survival curve tends to be Deevey II type, with low mortality in the early stage and stabilization in the later stage. The overall population dynamic index is positive, indicating that the population is in a growth phase and has high stability. (2) Time series prediction shows that the number of mature and middle-aged individuals will continue to increase in the future stage, the population has good regeneration capacity, and it can maintain a stable growth trend in the short term. (3) Environmental factor analysis shows that the intensity of disturbance and slope position are the dominant factors affecting the diameter class structure. Small diameter individuals tend to be in strongly disturbed habitats, while large diameter individuals are more likely to form in mid-slope environments.

Conclusion The Masson pine population in the initial treatment area of red soil erosion in Changting is generally growing and structurally stable, with good natural regeneration capacity. In forest management, the stand structure and environment should be optimized according to the differences in disturbance intensity and slope position, and appropriate forest gaps and suitable site conditions should be maintained to ensure the continuous regeneration of Masson pine population and promote the long-term restoration and stability of the ecosystem in the red soil erosion area.