Influence of tsunamis as large, infrequent disturbances on tree communities of coastal forests

Abstract

We investigated the population structure of trees in the coastal forests 3 months after the Great East Japan Earthquake to understand the impact of tsunamis. To clarify the impact on types of damage to trees, a belt transect (540 × 40 m) was set perpendicular to the shore line, transecting both the sand dune and back marsh. Species name and diameter at breast height (DBH) were recorded for both live and dead trees> 5 cm in DBH. Major types of damage were classified as "leaning", "stem breakage/bending", "uprooted", and "floating", and recorded for all trees. Species names were also recorded for living trees ≤ 5 cm in DBH. Elevations in the belt transect were obtained using a digital elevation model. Pinus thunbergii was the most numerous, followed by P. densiflora, Prunus spp., and Robinia pseudoacacia. All types of damage were observed in the back marsh, while uprooting and floating were almost absent on the sand dune. Seedlings and saplings of deciduous broad-leaved trees were observed in the back marsh. Those of P. thunbergii were observed both on the sand dune and in the back marsh. Continued monitoring of these biological legacies will be required for establishing multifunctional coastal forests.