Ornamental perennials in flowerbeds shaded by tree canopy: Succession over five years since the establishment

Abstract

Ornamental plantings are an integral part of modern landscapes transformed by humans. In the last decades, there has been a shift towards low-maintenance plantings with reduced energy input, associated with increasing use of easy-to-grow, profusely blooming taxa with broad ecological niches. However, such species can escape from cultivation, naturalize easily, become invasive, and cause environmental and socioeconomic problems. Our study focused on ornamental flowerbeds shaded by the canopy of trees; we studied the survival of the planted taxa in succession and patterns of dominance exchange over five years since planting and compared the results with those obtained previously for sunny ornamental flowerbeds. We recorded 155 taxa (53%) surviving from the initially planted species pool and 118 newly arrived colonizers. The surviving taxa increased or maintained the same abundance as they had at the beginning of succession. Generative reproduction was the main factor contributing to successful survival, followed by specific leaf area (SLA). We observed an increase in diversity, measured as the Shannon-Wiener index, in two of 11 flowerbeds but found no relationship between diversity and stability, calculated as a distance of initial and recent stage in ordination space. The same traits, namely tall stature and high fecundity were important in shaded and sunny assemblages, which were key factors for survival and performance in both environments. The presented results are not only important from the biological invasions point of view but can also help gardeners promote the long-term stability of flowerbeds and save resources necessary for future maintenance of flowerbeds.