Vascular flora of Lake Tofutsu (Tofutsu-ko), a Ramsar Convention site in Hokkaido, Japan

Abstract

Floristic surveys were conducted at Lake Tofutsu, a Ramsar Wetland of International Importance located in Abashiri Quasi-National Park, during 2001?2015 to obtain essential information for ecosystem conservation planning. In 2014, particularly intensive surveys were conducted throughout the growth season, including aquatic plant surveys by canoe. Voucher specimens were collected and deposited in herbariums. In total, 331 species from 82 vascular plant families were recorded, including 27 species red-listed by the Ministry of the Environment, Japan. Among these 331 species, 11 were found at Lake Tofutsu, 6 of which are red-listed species. We collected 44 alien species listed in the Hokkaido Blue List, mainly from roadsides and slopes. Our intensive surveys confirmed 130 species that have not been recorded in previous reports of the flora in Lake Tofutsu, demonstrating the importance of intensive and extensive floristic surveys. Compared with other surveys conducted at Lake Tofutsu, our survey did not confirm four previously recorded freshwater aquatic species. This finding suggests that environmental changes upstream of the lake may have had harmful effects on these aquatic plants.