Heracleum sosnowskyi (Apiaceae) seed productivity and establishment in different habitats of central Lithuania

A dangerous invader Heracleum  sosnowskyi successfully spreads along roads, riverbanks and has naturalized in Lithuanian habitats and plant communities. It out-competes native species, thus changing ecosystems diversity, pushing autochthone species from native habitats, decreasing biodiversity and transforming landscape. This paper aims to evaluate H. sosnowskyi spread and establishment on habitat scale in Lithuania. Data on abundance, spatial distribution and contribution of H. sosnowskyi to plant biodiversity were collected from natural and anthropogenic habitats. Another objective was to evaluate the speed of spread in an infected landscape. Local assessments of the abundance of H. sosnowskyi by estimating variables of spatial penetrating and establishment in native plant communities on an individual block scale were carried out. Four population types with different density and coverage of species individuals were found. Species abundance was structured according to the distance from highway and significantly correlated (r = 0.7) with native plant community type. This species finds opportunities for colonization and reproduction resulting in decrease of natural diversity.