Abstract
We conducted a flora survey in the post-mined Sphagnum peatland, Sarobetsu Mire, northern Hokkaido, to investigate the invasion status of alien plant species. The survey area covered a parking space and trails that were used during the mining operation, in addition to 21 mined sites. The effects of peat mining on invasion of alien species was assessed by comparing the species recorded before and after the peat mining and those of the un-mined peatland. In total, 123 species including 22 alien species and five red-listed species were recorded. Nine of the alien species are considered to have established due to peat mining because these species were not recorded either before peat mining or in the un-mined sites. The distribution of alien species was limited to the parking space and the trails; however, three species (Rumex acetosella L. subsp. pyrenaicus (Pourret ex Lapeyr.) Akeroyd, Rumex obtusifolius L., and Hypochaeris radicata L.) have established also in two mined sites where ground water level was relatively low. Rumex acetosella subsp. pyrenaicus and R. obtusifolius are known for their large ecological impacts, and have a potential to threaten endangered species and vegetation recovery after peat mining. Continuous monitoring would be necessary to avoid damage to native flora and landscape by alien species.
