Plant Diversity and Considerations for Conservation of It in Infrastructure Reconstruction Planning After the Great East Japan Earthquake and Tsunami of 2011

Abstract

This review examines the impacts of the Great East Japan Earthquake and Tsunami of 2011 and subsequent reconstruction activities on coastal plant diversity. Arable lands and coastal forests in lowlands areas were seriously and extensively damaged by the tsunami and by land subsidence. Although most salt marshes and back marshes were probably seriously damaged, new marshes have emerged in the lowlands. The vegetation on sandy beaches disappeared or was reduced in many areas. Sand dune vegetation at some sandy beaches survived the disaster and showed remarkable recovery. The influence of the tsunami and land subsidence on the plant communities of the coastal cliffs and on weed communities along roadsides and in vacant lots was limited. Threatened species, especially Potamogeton pusillus and Eleocharis parvula, appeared in inundated paddy fields and residential areas, in ponds and in wet areas within surviving coastal forest. The origin of these newly appeared plants has not been confirmed, but the possibilities include germination from the seed banks, transport from another location by the tsunami and seed dispersal from another area. Alternatively, the presence of the plants before the disaster might simply have been overlooked. Many infrastructure reconstruction projects were planned with little consideration for biodiversity. Most of the new tidal flats and salt marshes containing some threatened plants have already been lost due to infrastructure reconstruction and the resumption of cultivation on inundated arable land. Some attempts have been made to include biodiversity conservation in plans for infrastructure reconstruction.