Survival, growth and reproduction of sprouted individuals of star magnolia two years after clearcutting

Abstract

ABSTRACT Star magnolia, Magnolia stellata, is an endemic rare subcanopy tree species in the Pacific Ocean side of central Japan and an important component of Satoyama coppice forests in the area. This species is now faced with possible extinction due to the abandonment of Satoyama forests. To understand sprouting regeneration patterns of this species, to assist in its conservation, we defined four study plots whose area ranged from 156.25 to 500 m2 and clearcut all vegetation in 2012–2019. We recorded survival, growth and formation of flower buds at the individual level for two years after clearcutting. The average survival rate was 95.8%. Average tree heights in the first and the second year were 0.85 m and 1.36 m, respectively. Tree height in the first year was significantly positively correlated with the total basal area of stumps (TBA), which is assumed to be proportional to the amount of carbohydrates stored in stumps. The average percentage of individuals forming flower buds in the second year after clearcutting was 32.0%. The probability for forming of flower buds in the second year was increased with increasing in TBA and the model predicted that individuals whose TBA was above 381 cm2 had more than 50% probability of forming flower buds. Tree height in the second year for individuals with flower buds was significantly greater than those without. However, annual height growth of individuals with flower buds was significantly lower than those without. This indicates that a significant trade-off between height growth and reproduction exists.