Through the development process of collective housing sites in Senri New Town, planted areas in residential lots havebeen established as a component of natural and artificial environment of the area. Facing a challenge of restoring old collectivehousings, we intended to clarify characteristics of existing arbores in collective housing sites developed by Japan HousingCorporation. Applying data of tree height, branch spread, and trunk circumference, the characteristics of tree figure and itschanges were investigated by comparison of arboreal vegetation of two selected sites. Not only layout of buildings and open spaces but also maintenance practice of vegetation critically affected figures and growth of the trees. Among the findings, it wasnoted that development process, land formation in particular, of housing lot also affected their growth. In terms of decisionmaking on whether to conserve or transplant existing trees in restoration procedure, significance of those trees on the site shouldbe reorganized through evaluation on trees themselves, context of landscape and development process by revealing archivalrecords. Updating the records is also important to inherit the values of open spaces in collective housing sites as naturalenvironmental structure.
