Distribution, state and conservation of Equisetum telmateia in Lithuania.
Conservation of endangered plant species requires a thorough knowledge about the present state of their populations and habitats as well as identification of current and potential threats. The aim of this research was to evaluate current distribution, state of habitats and the size of populations of Equisetum telmateia (Equisetaceae) in Lithuania as well as to reveal the main threats and requirement for the conservation of this species. Analysis of all available information revealed that E. telmateia currently occurs in seven localities in Lithuania, mainly in the southern part of the country. One formerly recorded population in the south-western part of Lithuania has become extinct. Two reported localities in the environs of Druskininkai (southern Lithuania) are doubtful, because the reports have been based on misidentified specimens. Locality of E. telmateia in the western part of the country probably has been provided erroneously and one locality in the south-eastern region of Lithuania should be verified and the identity of the species requires confirmation. Total area occupied by the stands of E. telmateia in Lithuania is 2.41 ha. Most frequently this species grows in river valleys or close to rivers and occupies alluvial forest habitats, which frequently creates complexes with habitats of mineral-rich springs or springs with tufa formations. Occasionally it grows in the habitats of forests of slopes, tall herb fringe communities and hay meadows. Sporulation of E. telmateia in Lithuania is poor: no fertile shoots were registered in two studied populations, whereas in other localities few fertile shoots were recorded. Evaluation of the status of E. telmateia in Lithuania applying the IUCN criteria resulted in its categorization as a vulnerable species. The main threats for E. telmateia are forest logging and changes in habitat hydrological regime, though wild animals, human activities and invasive plant species also have certain negative impact on the populations of this species.