Heracleum Sosnowskyi Invasion in Lithuania on Regional Habitat Scale

Abstract

Heracleum sosnowskyi is among 7 dangerous invader species successfully spread along roadsides and naturalized^in Lithuanian habitats as well as in plant communities. This species acts compressively on native autochthones species thus changing community composition and structure. Local assessments of the abundances of Heracleum sosnowskyi by estimating variables of spatial penetrating and establishment in native plant communities at an individual block scale were caniea out. Four population types (solitary individuals, small groups of 1-2 individuals fruited; groups of nx10 rn diameter; strips of 1-10 m width and different length along forest, road, Nemunas river banks: and large pure colonies with density of nx10 individuals 10 m and coverage of 60-80% (100%) were found. Species' abundance was structured according to distance from highway and significantly correlated (n=0.7) with native plant community type. This species invasion success was the highest in roadside (12.3%), abandoned grassland (6.7%), and wasteland (2.4%) habitats.