2022 Volume 48 Issue 2 Pages 374-385
To clarify the change in soil carbon stocks due to changes in land use from forest land and cropland to settlements, we considered the research method targeting new towns and industrial complexes where building land and roads are integrated, as typical settlements. Soil surveys were then conducted at more than 30 points nationwide. With reference to these results and the location information of the points converted from forest land and cropland to settlements, etc., the initial values of soil carbon stocks in settlements were calculated to be 21.9±16.5 MgC／ha when converted from forest land, and 22.8±17.6 MgC／ha when converted from cropland. The various land use forms of the settlements were summarized into four land use categories based on the current statistical classifications: building land, roads, grassland, and parks. Based on past data and aerial photographs, the soil carbon stock changes in each land use category due to vegetation recovery after conversion was added to the initial values, and the average soil carbon stock in settlements overall was calculated as 28.1±17.5 MgC／ha. With this method, it is possible to respond to changes in the area ratio of forest land and cropland to be converted to settlements and the composition ratio of land use categories in settlements to be converted. Therefore, it is possible to regularly update the average soil carbon stocks in settlements.
