Evaluating spatial distribution of forested landscape in northern region of Okinawa main island based on topographic- and rainfall characteristics, timber harvesting activities, and land-use changes

The Yambaru region located in the northern part of Okinawa main island belongs to a subtropical marine climate zone. Such meteorological environment has created the bountiful forests of Yambaru and those forests have nurtured important habitats for a large number of internationally recognized endemic and native species. The Yambaru National Park was established in 2016 and comprises a land area of 13622 ha in the villages of Kunigami, Ōgimi, and Higashi. Presently there are efforts being made to designate the Yambaru forests as a World Natural Heritage Site. On another front, during the age of the Ryukyu Kingdom, the Yambaru forests were respectfully managed under the Somayama system established by Sai On who was Three Chancellor of the Ryukyu Court. Within this system, timber from the Yambaru forests was shipped mainly for building, for heating and for wooden products necessary for urban dwellers life and reforested areas after harvesting trees, thereby protecting the forest under a traditional practical knowledge. Now the Yambaru forests are owned by various stakeholders who include the government, prefecture, three municipalities, and individuals with different management goals. The critical issues being occurred in Yambaru forests are on how to improve society's perception and understand the sustainable forest management. This study was carried out to assess the potential forested landscape in Yambaru region through topographic and watershed properties, timber harvesting activities and population and land use transition. Three main parts of the study consist of 1) characterization of topographic and watershed attributes, 2) terrain analysis based on DEM and time series analysis of rainfall data, and 3) elevation- based zoning of forested landscape in Yambaru region.