Abstract
Invasion and establishment of tree species was surveyed in a part of the Oi Wharf. This is one of the reclaimed land in Tokyo Bay, formed by infill of waste materials and discarded soil. The vegetation of the study site was composed of perennial grass and herb communities dominated by the anemochorous plants such as Phragmites australis, Solidago altissima, Imperata cylindrica var. koenigii, Miscanthus sacchariflorus. The invaded trees scattered in the site were abundant under the electric cables and along the drains. Trees taller than 3m in height tended to be distributed near the drains. As almost all the tree species which appeared on the site (Prunus jamasakura, Celtis sinensis var. japonica, Rhaphiolepis umbellata var. integerrima, Ligustrum japonicum etc.) were endozoochores, their seeds seemed to have been dispersed by birds. The source of these seeds was thought to be the mature trees planted in the parks near the site. The electric cables act as perches, accounting for one of the trends of tree invasion. Since construction of the drains prohibits the expansion of those perennial grasses and herbs which make clonal growth by rhizomes, loosen soil compaction and extreme wet condition of soils, the areas adjacent to the drains must be suitable sites for the establishment of tree seedlings. The abundance of endozoochorous trees among the invading trees is a common characteristic of isolated forests in urban habitats. Thus, tree invasion on a reclaimed land seems to be influenced by the urbanization of surrounding areas. Moreover the C. sinensis var. japonica forest and the M. japonicus forest will be involved in the early tree phase of succession in the reclaimed land of Tokyo Bay.
