Soil preferences and morphological diversity of goldenrods (Solidago L.) from south-western Poland

Invasive plants in their new range can differ from their ancestors, including traits ultimately influencing habitat preferences, competitiveness and dispersal ability. In Europe Solidago species are considered as one of the worst invaders of American origin. In this study the frequency of occurrence of Solidago species, their soil preferences and morphological diversity, in Silesia (south-western Poland, Central Europe) were surveyed. On the basis of phytosociological relevés, made using the Braun-Blanquet method, in 75 plots, we determined the composition of species co-occurring with particular Solidago species. The height of ramets, as well as length and width of inflorescences of Solidago species were measured. We also determined the basic soil properties and noted the presence of trees overshading the ground vegetation. The compositional variation of vegetation and its relation to environmental traits: soil properties (texture, pH, percentage of organic matter, total nitrogen, nitrate, phosphorus, potassium and calcium content) and presence of canopy were analyzed by multivariate ordination methods (CA and CCA). Goldenrod species, in most cases (74.3%) occurred singly, two on one plot – rather rarely (mostly S. canadensis with S. altissima), whereas three Solidago species co-occurred only in three plots. Particular species differed in the height of the plant and inflorescence size, the exception was lack of difference between S. altissima and S. canadensis. S. virgaurea often occurred under trees canopy and the populations were separated from other goldenrod species. The species co-occurring with S. altissima and S. canadensis were the ruderal species, whereas plants from wet meadows occurred in plots with S. gigantea. The distribution of S. graminifolia was very limited, but inside its range it was able to occupy different habitats. The plots, where particular Solidago species occurred, did not differ significantly with respect to soil conditions