The soil seed bank of the threatened plant Magnolia stellata is subordinate to the emergence of current-year seedlings

Abstract

We studied seed bank formation of the threatened star magnolia, Magnolia stellata, to examine the early stage of regeneration. Forty-five seedling plots (2 × 2 m), each including a soil-sampling quadrat (40 × 40 cm), were established randomly under or around the crowns of mature M. stellata trees. Seeds of M. stellata were collected from each quadrat to a depth of 5 cm. Only four seeds of M. stellata were found (0.56 seeds/m²) and all were located under mature crowns. Current-year seedlings were abundant in water channels, on moss, or under mature crowns, suggesting that the seeds may require wet soil conditions for germination. Magnolia stellata seeds show considerable germination below the crowns of mature trees in the year following masting, while some seeds remain dormant in the soil. Considering the soil seed bank and the current-year seedling bank of M. stellata, a frequent supply of seed is essential for the regeneration of this species. Thus, it is important to maintain mature trees in addition to promoting seed production.

Keywords:

• Current-year seedling
• Magnolia stellata
• Soil seed bank
• Threatened species

Acknowledgments

We thank the government of Aichi Prefecture for permission to use the study site, A. Kanazashi and K. Ishida for supporting this study, Y. Nakamura for helping with the field survey, and two anonymous reviewers for critical review of the manuscript and for useful comments.