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Sökning: WFRF:(Dengler Juergen)

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1.
  • Becker, Thomas, et al. (författare)
  • Nutrient-poor grasslands on siliceous soil in the lower Aar valley (Middle Hesse, Germany) - neglected vegetation types in the intersection range of four classes
  • 2012
  • Ingår i: Tuexenia. - 0722-494X. ; :32, s. 281-318
  • Tidskriftsartikel (refereegranskat)abstract
    • In the lower siliceous uplands of Central Europe, various types of nutrient-poor grasslands are widespread and grow intermingled. These species-rich grasslands, often dominated by taxa of the Festuca ovina aggregate, comprise various phytosociological classes. They are remnants of a historic rural landscape and are of conservation importance. Few studies on such grasslands are available and there has been disagreement in assigning them to appropriate habitat types or syntaxa. We investigated such nutrient-poor grasslands in the lower Aar valley (Middle Hesse, Rhenish Massif). We surveyed 104 vegetation plots distributed throughout the valley and identified syntaxa to (sub)association level. We carried out supervised classification combining cluster analysis, a priori assignment to classes based on prevailing diagnostic species, and regional refinement based on phi-value maximisation of the units. As a result, we classified five associations within four classes: Polytricho piliferi-Festucetum tenuifoliae/Galio harcynici-Deschampsietum flexuosae and Festuco rubrae-Genistelletum sagittalis (Calluno-Ulicetea), Jasiono montanae-Festucetum ovinae (Koelerio-Corynephoretea), Gentiano-Koelerietum pyramidatae (Festuco-Brometea) and Arrhenatheretum elatioris (Molinio-Arrhenatheretea). Ecologically, soil acidity (resulting from Ca concentrations of the bedrock) was the main cause of floristic dissimilarity of the grasslands and thus community differentiation. Many stands grew on soils with intermediate pH and showed a peculiar mixture of basiphilous and acidophilous species. We conclude that (i) our approach of supervised classification yields convincing reproducible results when a syntaxonomic system is adapted top-down to a geographically restricted area, (ii) nutrient-poor siliceous grasslands dominated by taxa of the Festuca ovina aggregate can be well assigned to ecologically meaningful syntaxa, and (iii) the nutrient-poor siliceous grasslands of the Lahn-Dill Highlands are of high conservation relevance and in urgent need of protection.
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2.
  • Dengler, Juergen, et al. (författare)
  • GrassPlot - a database of multi-scale plant diversity in Palaearctic grasslands
  • 2018
  • Ingår i: Phytocoenologia. - : Schweizerbart. - 0340-269X. ; 48:3, s. 331-347
  • Tidskriftsartikel (refereegranskat)abstract
    • GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). GrassPlot collects plot records (releves) from grasslands and other open habitats of the Palaearctic biogeographic realm. It focuses on precisely delimited plots of eight standard grain sizes (0.0001; 0.001;... 1,000 m(2)) and on nested-plot series with at least four different grain sizes. The usage of GrassPlot is regulated through Bylaws that intend to balance the interests of data contributors and data users. The current version (v. 1.00) contains data for approximately 170,000 plots of different sizes and 2,800 nested-plot series. The key components are richness data and metadata. However, most included datasets also encompass compositional data. About 14,000 plots have near-complete records of terricolous bryophytes and lichens in addition to vascular plants. At present, GrassPlot contains data from 36 countries throughout the Palaearctic, spread across elevational gradients and major grassland types. GrassPlot with its multi-scale and multi-taxon focus complements the larger international vegetationplot databases, such as the European Vegetation Archive (EVA) and the global database " sPlot". Its main aim is to facilitate studies on the scale-and taxon-dependency of biodiversity patterns and drivers along macroecological gradients. GrassPlot is a dynamic database and will expand through new data collection coordinated by the elected Governing Board. We invite researchers with suitable data to join GrassPlot. Researchers with project ideas addressable with GrassPlot data are welcome to submit proposals to the Governing Board.
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