Nurse Effect of the Residual Canopies on the Survival of Evergreen Broadleaved Tree Seedlings Planted in a Coastal Pine Wilt Disease Stand

Abstract

Evergreen broadleaved tree seedlings are recently planted to maintain the function of coastal protection forest after pine wilt disease in the former pine stands on the coastal sand dunes. Those seedlings, however, have a problem of poor vigor in the early rooting stage. On March 2014, both evergreen broadleaved tree species of Neolitsea sericea and Machilus thunbergii were planted in a coastal pine forest where pine wilt disease has been proceeding and deciduous broadleaved trees have naturally been invading. This study examined the effect of light intensity, soil temperature and soil moisture that measured in summer on the survival of the two species. The residual pine and invaded tree canopies played a significant role as a nurse plant for the survival of the young seedlings. In addition, Neolitsea sericea and Machilus thunbergii were significantly influenced by light intensity and soil moisture, respectively. We concluded that sparse canopies should be retained to facilitate planting evergreen broadleaved seedlings in a coastal protection forests.