Vegetation-environment relationships in a heavy metal-dry grassland complex

• Autores: Thomas Becker, Markus Brändel
• Localización: Folia geobotánica: A journal of plant ecology and systematics, ISSN-e 1874-9348, ISSN 1211-9520, Vol. 42, Nº 1, 2007, págs. 11-28
• Idioma: inglés
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• Resumen

  • Heavy-metal content is assumed to be the most important edaphic factor that determines vegetation composition on contaminated soil. We compared the effects of heavy metals on species composition and species richness in the heavy metal-dry grassland complex of the BottendorfHitls (Central Germany) with those of other environmental factors. Based on 206 relevrs, we distinguished nine communities of the classes Koelerio-Corynephoretea and Festuco-Brometea. Four communities in which the metallophytes Armeria maritima subsp, halleri and Minuartia verna subsp, hercynica occurred with high frequency were classified as heavy metal subassociations of four different dry grassland associations because of the dominance of dry grassland species. We measured the soil content of copper, zinc and lead, and the carbonate content, C/N ratio, pH and conductivity of the soil, soil depth and incident radiation per site. The first axis resulting from a DCA was positively correlated with the cover and height of the herb layer, the soil depth and soil carbonate content, and negatively with the soil content of copper, the proportion of rocks, the soil C/N ratio and incident radiation per site. The number of vascular plants, bryophyte and lichen species per plot increased with pH up to 7.5 and then decreased slightly. Species richness increased with carbonate content and conductivity of the soil and decreased with the soil C/N ratio. Heavy metal content of the soil and species richness were not correlated. The occurrence of the metallophytes was strongly related to the copper content of the soil. In conclusion our study has shown that heavy metal content is not necessarily the main factor determining the total composition and richness of grasslands on soil containing heavy metals. Heavy metal grasslands are not necessarily floristically distinct from "normal" dry grasslands.