Abstract
The purpose of this study was to elucidate the restoration process of the flora at an artificial beach formed by sedimentation of drifted sand through the use of artificial structures, such as breakwaters. The Kasai Marine Park was built in 1976 near the Tokyo urban area to conserve the natural ecosystem. In particular, the East Beach area was constructed inside the park as a sanctuary for marine species, including coastal plants. The investigation of flora was conducted and vegetation maps were created in 1986, 1996, and 2001. We referred to these reports and investigated the coastal vegetation in 2008. We simultaneously collected the 7 documents in which the records of the coastal plants of the Tokyo Bay area (except for the Kasai Marine Park) had been published. These records were used for the analysis of our field investigation data. Results showed that in the Kasai Marine Park, the area of vegetation had spread and the number of plant communities and species had increased over time. From the detailed analysis of the Kasai Marine Park flora, we showed that both the coastal grassland plants and the sea cliff plants had increased over time, contributing to the return of native beach flora to the Kasai Marine Park. Because U-shaped (open toward the offing) breakwaters often catches the sand drifts, resulting in the formation of various microtopographies in this area. These have enabled the immigration of more coastal plants over time. In this study, we identified the basic species of coastal vegetation in Tokyo Bay. The number of species and areas of beaches were significantly correlated. These results enable the prediction of the number of species required in the creation or restoration of the coastal beaches in future. Our results provide useful information for the rehabilitation and restoration of the Tokyo Bay.
