The structure and differentiation of the synanthropic flora of the botanical gardens in Poland

Abstract

Floristic studies were carried out in eight botanical gardens in Poland in the years 1992-1999. It was demonstrated that the spontaneous synanthropic flora of the gardens consisted of 1092 taxa in the rank of a genus or lower, among which alien species constituted 55% of the flora studied. Ergasiophygophytes, of which the introduction is closely associated with the activities of the botanical gardens, dominated in the latter group of species. It appeared that the flora of the studied botanical gardens was rather similar. However, the structure of the flora of different spatial units (six types of microhabitats) distinguished in the particular gardens varied, which was associated with the various management practices. The flora of microhabitats identified in the gardens differed with respect to the number of taxa and spectra of geographical-historical groups of species and life forms. Ruderal sites, arable lands and roadsides supported the highest number of taxa (the flora of the above spatial units was represented by 646, 645 and 597 taxa, respectively). Moreover, they were characterized by a high proportion of annual plants in the flora (43, 38 and 34%, respectively) and by a relatively small representation of apophytes (39% in all the three types of microhabitats). The flora of wet areas and parks was, however, poor in species (154 and 403 species, respectively), but relatively rich in apophytes (72 and 55% of the flora, respectively) and with a low contribution of therophytes (19 and 20%, respectively). The present data were compared with the findings of other authors who investigated the synanthropic flora of cities in which the botanical gardens were located. The comparative analysis of the flora of Poznań and Łódź showed a great richness of species (in relation to size of the area studied) and a high incidence of aliens (especially those, which had not become established permanently) in the botanical gardens. However comparative studies of the flora of Warsaw and that of the two botanical gardens established in the city revealed that the proportion of alien species was lower in case of these gardens. In Warsaw the flora of areas, which had been managed in the same way as those of the botanical gardens, was also investigated. It was found that the botanical gardens in Warsaw were more similar to cemeteries with respect to the structure of flora than they were to the allotments. The present study showed that the high variability of flora within the particular gardens is attributed to the different ways the area is utilized.