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Accueil du site → Doctorat → Allemagne → 2005 → The occurence of acidophile/calcifuge plant species in semi-arid calcareous grasslands

Georg-August-Universität Göttingen (2005)

The occurence of acidophile/calcifuge plant species in semi-arid calcareous grasslands

Fühner Christoph

Titre : The occurence of acidophile/calcifuge plant species in semi-arid calcareous grasslands

Auteur : Fühner, Christoph

Université de soutenance : Georg-August-Universität Göttingen

Grade : Doktorgrades der Mathematisch-Naturwissenschaftlichen 2005

The deviating vegetation composition of habitats with alkaline, calcareous and acid, non-calcareous soils is subject of one of the oldest, nevertheless not finally solved problems in plant ecology. Embedded in a comprehensive ecophysiological and ecological study of the calcicole/calcifuge-complex, the reasons for the exclusion of acidophile/calcifuge plants from alkaline, calcareous soils are treated here on the basis of comparative phytosociological and pedological investigations of two subassociations of the Gentiano-Koelerietum, a phytosociological category of semi-arid calcareous grasslands widespread in Central Europe. Whilst, in the typical subassociation of the Gentiano-Koelerietum, basiphiles/calcicoles predominate, the Gentiano-Koelerietum danthonietosum is characterized by the simultaneous occurrence of taxa with acidophile/calcifuge traits, e.g. Calluna vulgaris. Considering especially ecological aspects of plant mineral nutrition, a wide range of physical and chemical soil analyses were performed on six semi-arid calcareous grasslands, which include both subassociations in immediate vicinity, and therefore under similar geological and geographical conditions. Located in the centre of Germany, most of the study sites are covered by shallow calcaric leptosols with alkaline pH-values in the topsoil originating from calcite of the Upper Muschelkalk or dolomite of the Zechstein. For the investigation of the soil chemical properties, both, standard and novel extraction methods were applied. The spatial and chemical selectivity of the innovative techniques allowed a more tightly focussed examination of fractions with special reference to the mineral nutrition and potential toxic effects to the plants. The study concentrated on the availability of Fe and P due to their possible role as the crucial factors limiting the growth of acidophile/calcifuge plants in alkaline, base rich soils. Germination and growth experiments on selected acidopiles/calcifuges and basiphiles/calcicoles complemented the ecological analyses of the study sites. In addition, aspects of palaeogeography and evolutionary biology as well as the relevance of microbial symbiosis for the vegetation differentiation are considered in the discussion of the experiments. Considering the general differences in Fe efficiency between acidophile/calcifuge and basiphile/calcicole species, the results of the edaphic analyses are in accordance with the hypothesis of inadequate Fe availability to acidophile/calcifuge taxa on alkaline, calcareous and dry soils. However, no correlation was found between the P solubility and the growth of acidophile/calcifuge plants in semi-arid calcareous grasslands. Due to the fact that, to date, site-specific efficiencies of the equally oligotrophic acidophiles/calcifuges and basiphiles/calcicoles are not satisfactorily proven it has to be accepted that the supply of these nutrients to the plants is not exceeding secondary, indirect importance for the differentiation of the Gentiano-Koelerietum and the exclusion of acidophile/calcicole taxa from alkaline, base rich soils.

Mots clés : acidophil ; basiphil ; calcicol ; calcifug ; Kalk-Halbtrockenrasen ; Vegetationsdifferenzierung ; Kalkboden ; Boden-pH ; Eisen ; Phosphor ; Phosphat ; Stickstoff ; Calciumcarbonat ; Hydrogencarbonat ; Eisendefizienz ; Mineralstoffernährung ; Mineralstoffökologie ; Nährstoffmangel ; Nährstoffeffizienz ; Mineralstofftoxizität ; Mineralstofftoleranz ; Ökologie ; Autökologie ; Ökophysiologie ; Synökologie ; Mineralstoffökologie ; Symbiose ; Bodenanalytik ; Bodenlösung ; Boden-pH ; Calluna vulgaris ; Danthonia decumbens ; Koeleria pyramidata ; Potentilla neumanniana ; Potentilla erecta


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