Survival, dynamics of spread and invasive potential of species in perennial plantations.
Ornamental plants represent an important source of alien and potentially invasive taxa. They are grown in a broad range of habitats such as home gardens, public spaces, belts along roads, floriculture plantations and specialized garden collections. Recently so-called "mixed perennial beds" are becoming increasingly popular as they need less maintenance compared to traditional plantings. Old perennial plantations with known initial composition, monitored for a long period of time, can provide useful insights into the naturalization and invasive potential of individual species. We studied survival and spread of ornamental plants by using data from flower beds established in 2006-2010, and resampled in 2016, and related these dynamics to the traits of the taxa (height, SLA, reproduction), taking into account their phylogenetic relationships. The height of plants and generative reproduction had a positive effect on survival. Taxa taller than 1 m and with massive and regular generative reproduction survived best. In the majority of beds, one to three taxa increased their abundance at the expense of others. These dominants were mainly alien such as Aquilegia sp., Aster dumosus, Knautia macedonica and Silene coronaria, that were also able to spread into neighbouring flower beds where they have not been originally planted.