ABSTRACT
The regeneration of Korean pine (Pinus koraiensis Sieb. et Zucc.) is a core issue for restoration from secondary to primary forests in northeastern China. However, Korean pine exhibits limited recruitment within its own canopy in primary forests, but demonstrates excellent regeneration in secondary forests. Until now, the mechanisms underlying this phenomenon have not been satisfactorily explained. Hence, we conducted studies in both primary and secondary forests to investigate whether light availability during the non-growing season determines the fate of regeneration. In spring and autumn, understory light availability in the secondary forest was significantly better than that in the primary forest. The biomass and non-structural carbohydrate (NSC) concentrations of natural pine seedlings were considerably greater in the secondary forests compared to primary forests. The carbohydrate concentrations increased during spring and autumn and decreased in summer. In the manipulation experiment, the biomass of seedlings was positively correlated with the organ NSCs in spring, while the survival rates were correlated with NSCs in autumn. The light availability during the spring and autumn seasons may have a crucial role in the regeneration of Korean pine seedlings. This finding may support our practical management approach for the transformation of secondary forests into Korean pine forests.
Acknowledgments
The authors thank all colleagues who assisted with field work, data processing, and manuscript composition and Zhenzhao Xu, Wenxian Du, Weize Xu, Zhen Sun, and Zhiyuan Yang, who helped with chemical analysis. The National Research Station of Changbai Mountain Forest Ecosystem provided accommodation and experimental sites.
Author contribution statement
GZ designed the study, performed sampling, and wrote the manuscript, JW and JY analyzed the data, SM revised the introduction and discussion, and SM and GZ oversaw the experiment.
Disclosure statement
No potential conflict of interest was reported by the author(s).