Vast and beautiful grassland landscapes in the Aso Kuju National Park have been maintained by human activities e.g. controlled burning, pasturage and mowing. However, the aging of local farmers and the stagnation of livestock industry make such grassland management increasingly difficult.

The purpose of this study is to clarify land improvement method of early collective housing sites developed by Japan housing corporation during 1960's-70's constructed on marshland on Nakagawa lowland in Saitama prefecture - Misato, Yoshikawa, Takesato, and Soka-Matsubara.

Dyera polyphylla, which is locally known as jelutung, is a tree that produces latex. The latex is used for chewing gums, insulator, tube, and others. The wood is soft and bright colour, which can be used for pulp, plywood, pencil, wooden toy, and others.