Natural Regeneration Patterns of Juglans mandshurica in Different Habitats

Abstract

The natural regeneration of Juglans mandshurica (Juglans mandshurica Maxim.) is challenging. To elucidate its regeneration patterns, we conducted a comparative analysis of the spatial distribution and regeneration indices of Juglans mandshurica seedlings across different habitats, from the forest edge to the inner forest, over a span of 1000 m. Our findings revealed significant differences in seedling growth and regeneration patterns among these habitats. The growth indicators of Juglans mandshurica seedlings were notably higher at the forest edge compared to other habitats. The proportion of Juglans mandshurica seedlings was lower than that of 1- and 2-year-old seedlings, with only 7% being young seedlings at the forest edge. Juglans mandshurica renewal seedlings were aggregated, with the degree of aggregation as follows: 15 m > forest edge > 60 m > 30 m. The regeneration index was highest at the forest edge (1.0) and decreased with distance: 15 m (0.62), 30 m (0.52), 60 m (0.42). Shrub species and other seedlings at the forest edge showed a significant negative correlation with the Juglans mandshurica seedling numbers (p < 0.05). At 15 m, tree species displayed a significant (p < 0.05) or highly significant (p < 0.01) negative correlation. Stand closure at 30 m exhibited a substantial (p < 0.05) or highly significant (p < 0.01) negative correlation with the Juglans mandshurica regeneration index. At 60 m, the tree species, number, and basal area at breast height showed a significant (p < 0.05) or highly significant (p < 0.01) negative correlation with the Juglans mandshurica regeneration index. The forest edge had the highest renewal index and effectiveness, making it a priority for the conservation and management of Juglans mandshurica renewal. This study provides a theoretical foundation for the conservation and sustainable management of Juglans mandshurica populations.