Abstract
In southwest Japan, there are many small wetlands formed and maintained by anthropogenic disturbance,
including Sphagnum wetlands. The main species is Sphagnum palustre, which is listed in the red lists of all the prefectures in the Chugoku Region, Japan. However, studies have not clarified the relationship between anthropogenic disturbances and environmental conditions of Sphagnum wetlands. This study surveyed a Sphagnum wetland developed on a farmland in Tsuguro Highland in Okayama Prefecture. Local elderly residents were interviewed, and aerial photographs were interpreted to gather information on the history of the agricultural reclamation. Multilayer vegetation maps were drawn using unmanned aerial vehicles (UAVs) light detection and ranging (LiDAR) data. The groundwater level, water quality, and relative solar radiation were measured. Also, the terrain was analyzed as an abiotic factor. The farmland was reclaimed and abandoned in the 1970s and 1980s. A decision tree analysis determined the threshold value of abiotic environmental factors of Sphagnum palustre, and lower limits were set for the groundwater level and the relative solar radiation. Additionally, the potential habitat of Sphagnum palustre was estimated based on the threshold value, which displayed a high level of corresponding ratio in relation to the actual habitat. The habitat of Sphagnum palustre consisted of the agricultural reclamation up to the boundary of the valley bottom with the high water level and the half shade conditions provided by shrubs, such as Rosa paniculigera. It grows under shrubs, owing to the relatively low light conditions provided by the shade of the shrubs. In the study site, it was estimated that a suitable condition for Sphagnum palustre was provided by a high groundwater level caused by spring water flowing into the agricultural reclamation area, which has low water permeability and is invaded by shrubs.
https://ror.org/024yc3q36 
