Growth responses and shade tolerance of eight broadleaf tree species

Coastal forests on sandy beaches in Japan are mainly established by Pinus thunbergii Parl.. These forests prevent and mitigate disasters such as wind, sand, tide, and tsunami. But Pinus thunbergii die-off is progressing nationwide in Japan and the function of coastal forests is declining. Therefore, a multi-tiered forest has been proposed composed of Pinus thunbergii and broadleaf trees instead of Pinus thunbergii trees. However, few studies have quantitatively evaluated the shade-tolerance characteristics of the broadleaf trees that comprise these forests. To this end, we measured chlorophyll levels (SPAD value) in eight representative evergreen broadleaf tree species inhabiting coastal areas in Japan and evaluated their shade-tolerance.