Plant communities on metalliferous soils in northern Greece

Abstract

We studied dry stony habitats with metalliferous soils (with various amounts of Cd, Cr, Cu, Fe, Mn, Ni, Pb, Zn) at low to moderate altitudes in 22 localities in northern Greece using 193 original phytosociological releves with vascular species composition, species abundance and topographical data. Soil samples were collected in 86 plots and analysed for acidity, heavy metal content and other parameters. The alms of the study were to classify the releves, describe the plant communities, assign species and communities to syntaxa, relate environment, distribution and species composition, and to compare the relative importance of soil metal content and the other environmental variables for species composition. We found 16 vegetation clusters and assigned them to 12 associations and corresponding plant communities. Each community is defined with respect to species composition and richness, ecology and distribution. The range of communities is heterogeneous and comprises 8 vegetation alliances belonging to the orders Alysso alyssoldis-Sedetalia, Astragalo-Potentilletalia, Hyparrhenio-Brachypodietalia ramosi, Sedo-Scleranthetalia, Thero-Brometalia and Tuberarietalia guttati. Two alliances and five associations are described as new syntaxa, and several more syntaxa, including some orders, have not been recorded from Greece and the southern Balkans before. Soil acidity and, secondly, the degree of substrate consolidation and vegetation development were identified as most important environmental factors explaining the chief floristic gradients in the data set. Heavy metal content turned out to be of secondary explanatory value, relevant in partial data sets of acidic base-poor soils or calcareous/ultramafic soils. Most species found on metalliferous soils are therefore facultative metallophytes, while obligate metallophytes are few and characteristic of ophiolithic substrates (serpentinophytes).