Mapping of alien species of Asclepias syriaca and Fallopia japonica populations in the agricultural landscape

In recent years, Asclepias syriaca, a invasive neophyte, has spread aggressively in intensively farmed agricultural landscape in the Central Slovakia. In 2011, it had colonized the area of 100 654 m2 in abandonment vineyards and permanent grasslands in the district of Velký Krtis (South Slovakia). We found the infiltration of these plants into the stands of Triticum aestivum and Helianthus annuus. No management measures were taken. In contrast, the second studied invasive plant Fallopia japonica had occupied area lower by 93% (7276 m2), but spread across higher number of sites (19) on the banks of the brooks and along the roads. Regulated populations accounted for only 11% of the total area occupied by F. japonica. Low correlation dependence was found between the size of the area and population density of A. syriaca (r = 0.50) and F. japonica (r = 0.56).