Present status of Sphagnum wetland development following surface soil removal in Kuromatsunai, Hokkaido

The Raiba wetland (approximately 0.9 ha) is a Sphagnum wetland that was discovered in the Kuromatsunai lowlands of Hokkaido, northern Japan, in 2011. We reconstructed the land-use and land-cover history of the wetland (1948-2005) using aerial photo interpretation and information obtained through interviews with local people. Our analysis revealed that the present wetland vegetation has developed through natural colonisation following anthropogenic disturbance, consisting of surface soil removal and road construction for residential development around 1976. In the wetland, we recorded Sphagnum squarrosum and 111 vascular plant species, including 4 threatened species and 8 alien species. The Sphagnum patch was significantly associated with areas of bare soil exposed after soil removal. These results suggest that past removal of surface soil has had a major influence on the present state of the vegetation in this wetland