Abstrakt
Ornamental plants constitute an important source of alien, and potentially invasive species, but also include a substantial part of native flora and consist of taxa that occur both in the wild and in cultivation; yet garden floras are largely ignored in ecological studies. We studied ornamental plants in the Czech Republic in order to provide detailed information, based on field sampling, on the diversity of taxa grown in cultivation in private gardens.
Sampling was done in accessible public areas, private gardens and private areas in villages, town- and city neighbourhoods, garden allotments, cemeteries, areas of dispersed farmhouse settlements not accessible to the public, and in new urban sprawl. The data can be used to estimate the propagule pressure of individual taxa, measured in terms of the frequency with which they are planted in the gardens.
To make the data comparable across sites, we adopted a two-level approach that resulted in producing a detailed list (including all the taxa recorded) and an aggregated list (merging closely related and similar taxa, which was necessary in order to assess the frequency of planting across sites). Each species on the detailed list was assigned an origin, status, life history and cultivation requirements.
Comparing the field records with national checklists of both native and alien vascular plants we quantified particular components of the ornamental flora. The floristic inventories for 174 sites yielded 1842 taxa on the detailed list, consisting of 1642 species (standard binomials), 9 cultivars assigned to genera, 147 hybrids and hybridogenous taxa, and 44 taxa identified at higher than species level.
Of these taxa 1417 (76.9%) were alien and 420 (22.8%) native. The ornamental flora consisted of not-escaping aliens, escaping aliens and cultivated natives.
Of the recorded taxa, 841 (45.6%) occur both in cultivation and the wild.