From European priority species to characteristic apophyte: Epipactis tallosii (Orchidaceae)

Epipactis tallosii is considered as one of the highly threatened European orchid species due to its local distribution and small isolated populations that are characterized by decreasing trends. The species is now enlisted in the endangered (EN) category of the Red List. Nevertheless, during the last decade, multiple new populations of the species were found in Hungary, while our field surveys indicated that E. tallosii populations regularly occur in poplar (Populus) plantations. Here we conducted a thorough field survey of poplar plantations, by visiting 182 plantations in Hungary and surrounding countries in the Pannonian Biogeographic Region. We found E. tallosii in 23% of the visited plantations, and counted a total of c. 4000 generative shoots. Moreover, we documented the occurrence of the species to four countries, where it has not been reported before: Croatia, Romania, Serbia and Ukraine. Alien and indigenous/mixed poplar plantations were similarly likely to harbour populations of E. tallosii. Our study suggests that the distribution area and number of populations of E. tallosii is much larger than previously assumed, and that poplar plantations serve as suitable habitat islands in the agricultural landscapes for this orchid. In the light of our results, we suggest the reassessment of the IUCN category of E. tallosii and to re-categorize it as Near Threatened (NT).