The effect of development on coastal sand dune vegetation in Shonan coast, Kanagawa Prefecture, Japan

Abstract

This study focuses on the effect of the reduction and fragmentation of sand dunes on the development of coastal sand dune vegetation in Shonan coast, Kanagawa Prefecture, Japan. Changing area and distribution of sand dunes were examined by land use maps over three time periods. The effect of development on coastal sand dune vegetation was examined by comparing the changes before and after the development of the Tsujido sand dune. The area and width of the sand dunes has been reduced by two-thirds from 1921 to 2006. Landform transformation from sand dune to urban area or coastal forest had a more significant impact on the reduction of sand dune than coastal erosion. The three distinct zones of vegetation observed in the Tsujido sand dune are unfixed, semifixed and stabilized zones, going from the shoreline inland before the development of the sand dune. It was found that the semifixed zone disappeared after the development of the sand dune, due to the reduction of sand dune. A portion of coastal sand dune vegetation has been isolated in the back of the coastal forest after the development of the sand dune. As a result, coastal plants except Fimbristylis sericea have disappeared, so that inland and alien species have been successfully established on these areas due to barrier effect of the coastal forest. It was concluded that sand dune development destroyed the zonation of coastal sand dune vegetation due to the reduction of sand dune, and resulted in the establishment of inland and alien species due to fragmentation.