Abstract: Soil quality is closely related to the secondary succession of forests. Studying the evolution of soil quality of the temperate conifer and broad-leaved mixed forests during the secondary succession in the Changbai Mountain can provide important scientific basis for the recovery and management of the secondary forests in this region. In this study, we investigated the change trend of soil indicators and the evolution characteristics of soil quality during secondary succession of temperate conifer and broad-leaved mixed forests in Jiaohe, Jilin Province. Soil total carbon and total nitrogen contents showed synergistic changes during the secondary succession, but no unified response of other soil indicators. Results of the principal component analysis showed that soil properties of the mature forest and old-growth forest were gradually far away from that of the middle-aged forest and near-mature forest. There was no significant difference in soil quality index at 0-10 cm soil depth among different succession stages, while soil quality index at 10-20 cm soil depth of the mature forest was significantly lower than that of the other three succession stages. Soil quality index increased with the abundance of broad-leaved tree species. The abundance of broad-leaved tree species explained 63.3% of variation of soil quality index at 10-20 cm soil depth during the secondary succession (P<0.001). In conclusion, changes in the abundance ratio between broad-leaved and conifer species during the secondary succession may be one of the important factors influencing soil quality evolution in the temperate conifer and broad-leaved mixed forests. Therefore, increasing the proportion of broad-leaved trees in the temperate conifer and broad-leaved mixed forests in the Changbai Mountain during the recovery and management of the forests may be beneficial to the maintenance of soil quality.

Key words: Changbai Mountain forest region, secondary succession, soil property, principal component analysis, soil quality index