Land-Type Classification and Ecological Land Evaluation in Izena Island, Okinawa, Japan

Abstract

This study aims to discuss the method of land-type classification and ecological land evaluation especially for the landscape conservation in Izena Island located in Okinawa Islands, southwest Japan, wherein geographical distributions of plant communities (actual vegetation) were phytosociologically surveyed by the author et al. (1978).First of all methodological discussion concerning land classification, the concept of which has been reviewed by many applied geographers like MABBUTT (1968), was carried out. In this article the author proposed “potential natural vegetation (TUXEN 1956) and landform” -oriented land classification as a sort of bio-physical land classification from genetically interpreted landscape approach. This method of classification is considered to be useful for land evaluation because of the integrated character of the two indexes and the appropriateness of forming a connection with land-use through actual vegetation which is influenced by both land potentiality and land use.In this study island land was classified into 13 bio-physical land units and their connection with other land elements such as surface geology and soils was considered. Such land units were mapped and connected with land use by using vegetational substitution. In the contemporary relationship possibility of land uses and land-use forms seem to be dependent upon the potentiality of land units. It is suggested that land evaluation can be performed through consideration of the way the relations between land units and land uses should be planned from the ecological point of view in the future. Concerning such ecological land evaluation, land units have summarized into 6 evaluated groups which present common characters for the countermeasures of land conservation. Then, in the specified area of the study island, land evaluation was tried for the purpose of protection of nature and recreation. This is an example of a landscape plan based on the results of land evaluation, which include the importance of land conservation, the value of natural or semi-natural vegetation and the desirability of land for the construction of roads, footpaths and recreational facilities. As a result of the case-study, the effectiveness of land classification and ecological land evaluation has been suggested.This study is a preliminary attempt to join the geographical and ecological method to landscape planning through land-type classification and evaluation. This sort of approach seems to get much importance under the critical circumstances for the development planning in Japan, especially in the humid subtropical islands where land potentiality for developments is relatively low and land itself is very limited.