Abstract: Canopy structure and understory light environment play an important role in the distribution and growth of naturally regenerated seedlings. Here, we analyzed the effects of canopy structure on naturally regenerated seedlings of Picea asperata secondary forest in Guandi Mountain by one-way ANOVA and Poisson correlation test. The number of naturally regenerated trees was the largest when the canopy openness (CO) was 19.5%-24.5% and the transmitted diffuse solar radiation index was 4-5. The optimum CO, transmitted direct solar radiation, and transmitted total solar radiation of seedlings were higher than those of saplings, while the optimal leaf area index (LAI) was lower than that of the saplings. Canopy structure and understory light were not significantly related to the growth of seedlings. Seedlings and saplings had different adaptation ranges to the understory light environment. There were significant differences in LAI and light intensity among the plots with different densities of regenerated seedlings. Our results provide a theoretical basis for understanding the natural regeneration of forests in this area.

Key words: canopy structure, natural renewal, canopy opening, leaf area index.