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Many current approaches to the formal definition of vegetation units have the disadvantage of leaving a large amount of relevés unclassified. In this paper I propose a new method for the unambiguous assignment of relevés, which is based on the summarised cover value of diagnostic species. In the first step, a relevé is assigned to the class with the highest cover score. For this purpose, the character and differential species of the class as well as the character species of all subordinated syntaxa are considered diagnostic. Once the class has been determined, the assignment proceeds successively to the lower ranks. This method, which may be called “summarised percentage cover approach”, uses solely the diagnostic species of syntaxa for the assignment of relevés to vegetation units, making additional formal definitions unnecessary. As a test data set, I used 487 relevés of fringe vegetation and grasslands of nutrient-poor sites sampled in the Vienna Woods (Wienerwald), Austria. All relevés were provisorily classified at alliances level, mostly following the assignment of the original authors. TWINSPAN and DCA were applied to evaluate this preliminary classification. Diagnostic species for both the alliance and the class level were identified using the total cover value ratio as fidelity measure. The subjective classification was largely confirmed by the numerical methods. On basis of the summarised cover of Trifolio-Geranietea and Festuco-Brometea species, between 64% (Geranion sanguinei) and 99% (Seslerio-Festucion pallentis) of the relevés were reassigned to the same class as in the original classification. The fact that a considerable amount of relevés originally classified as Geranion sanguinei was reassigned to grasslands reflects the problems in delimiting fringe communities rather than a poor performance of the assignment method. The “summarised percentage cover approach” allows not only for the unequivocal assignment of relevés to an existing classification system, but may also help to improve classifications by clarifying the delimitation of higher syntaxa.
Mit der dritten Auflage des Internationalen Code der Pflanzensoziologischen Nomenklatur wurde ein spezielles Komitee etabliert, um eine Entscheidung der Nomenklaturkommission über eingereichte Vorschläge für nomina ambigua, nomina inversa, nomina mutata und nomina conservanda zu erleichtern und zu beschleunigen. Wir legen hier den ersten Report dieses Komitees vor. Im ersten Teil der Arbeit wird ein kurzer Überblick über die Hauptprobleme mit jeder einzelnen dieser vier Kategorien gegeben. Im zweiten Teil werden 19 Vorschläge diskutiert und eine Empfehlung gegeben, ob der Vorschlag akzeptiert oder abgelehnt werden sollte. Autoren, die einen Vorschlag an die Nomenklaturkommission senden möchten, werden gebeten, diesen Report als Richtlinie zu nutzen.