Long-term monitoring of tree population dynamics of broad-leaved Korean pine forest in Changbai Mountains, China. 
Based on four investigations of a one-hectare permanent plot in Changbai Mountains from 1981 to 2016, the changes of tree species composition and structure of broad-leaved Korean pine forest were examined, and diameter distribution, spatial pattern distribution, and quantitative changes of each tree species were analyzed.  The results showed that there were little changes in tree species composition and an overall decreasing trend in total density in 35 years.  Both basal area and stand volume were 43-45 m2·hm-2 and 474-496 m3·hm-2, respectively.  Pinus koraiensis was the most dominant species, whose basal area and volume accounted for 57.8%-59.7% and 62.5%-65.4% of the total in the community, respectively.  All dominant species showed random distribution and changed little in 35 years.  The DBH distribution of P. koraiensis was in a near-to-normal form.  Total species showed a reversed "J" shape.  The number of dead trees was the largest in small DBH class (10-26 cm) with the percentage of 30%.  The percentage of dead trees was the largest in intermediate class (30-50 cm) with 30%-50%.  Except Acer mono, all species in the tree layer showed little recruitment, with mortality rate being higher than recruiting rate.  Specially, P. koraiensis had no saplings or recruitment, and the population was in decline.  The regeneration of dominant species such as P. koraiensis and Tilia amurensis was hindered in the original broad-leaved Korean pine forest, the population maintenance of which might need natural disturbance.