Metallophytes and Metallicolous Vegetation: Evolutionary Aspects, Taxonomic Changes and Conservational Status in Central Europe

Abstract

During the last decades the scientific focus has been on eco-physiological adaptations of metallophytes (for an overwiew see Baker et al., 2010), their community context and syntaxonomical evaluation (e. g. Libbert, 1930; Schwickerath, 1931; Koch, 1932; Schubert, 1953/54; Ernst, 1965, 1966, 1968, 1974; Koch & Kuhn, 1989; Daniels & Geringhoff, 1994; Pott & Hellwig, 2007), bio-geographical aspects (e. g. Schulz, 1912; Wein, 1926; Heimans, 1936; Schubert 1954a; Ernst, 1974), and their taxonomical status. Since the basic work of Schulz (1912) metallicolous ecotypes of vascular plants have received special attention in numerous publications, and several (endemic) taxa of dubious value have been described. Modern molecular methods (isozymes, DNA fingerprint and sequence analyses) allowed new insights into genetic differentiation of metallicolous populations, micro-evolutionary processes and the taxonomical treatment of several metallophyte taxa. Some scientific studies dealing with genetic differentiation of the character species of metallicolous vegetation (e. g. Minuartia verna, Silene vulgaris, Armeria maritima, Viola calaminaria, Cardaminopsis halleri, Thlaspi caerulescens) have shown that the taxonomic rank of some of them should be reconsidered. From this and due to new studies on vegetation composition syntaxonomical changes seem also to be necessary. Remarkable problems for the definition of habitat types may arise from this because the perception of the conservation authorities is focussed on the few character species of metalliferous vegetation.