Order (plant sociology)

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The order is a rank in plant sociology in which the vegetation is divided into plant communities (or phytozoenoses ) according to floristic similarity, i.e. according to the similarity of the composition of plant species. The order is one of the four main grades of the plant-sociological system, it follows on the third level after the association (the basic unit of the system) and the union . Orders are grouped into classes , the highest-ranking main grade . Many vegetation experts finally combine the classes into plant formations . Formations are not dealt with in syntaxonomy, however, as they are not defined according to the floral composition.

The order (also Latin: ordo) can be broken down into subordinate orders (subordo), but this structure is optional. Names of orders are formed with the standardized name ending " -etalia " and can be recognized by it. For example, the European acidic oak forests are included in the order Quercetalia robori-petraeae . If subordinates are differentiated, the name ending " -enalia " is binding. As in the other ranks of syntaxonomy, the ending is added to the name (or the root of the name) of a plant genus , in the example of the genus Quercus , followed by the species name ( epithet ) placed in the genitive . This is often left out, but it is necessary if the name would otherwise be ambiguous or ambiguous, in the example for the Quercetalia pubescentis; these are named after Quercus pubescens , the downy oak , the former after Quercus robur and Quercus petraea , the pedunculate oak and the sessile oak . The short name “Quercetalia” would therefore be misleading. As a rule, the name of the order is derived from that of one of its associations or associations, so that these units can then only be distinguished by the ending, for example (in the beech forests ) Fagetalia (sylvaticae) and Fagion (sylvaticae).

This results in the ranking:

  • Association, ending -etum.
    • Association, ending -ion.
      • Order, ending -etalia
        • Class, ending -etea.

As usual, a set of rules in a scientific publication must have been published “validly” (in compliance with certain formal regulations). In scientific papers dealing with syntaxonomic questions, the name of the first descriptor, often abbreviated, appended to the name of the order, often combined with the year of the first description (this is also occasionally abbreviated), for example Quercetalia robori-petreae Tüxen 1937. The syntaxonomic names are very unstable due to the relatively young age of the research direction and the standards developed over time, so that numerous synonyms can be found in the literature, although the name changes are not infrequently made for purely nomenclature reasons. For example, many syntaxonomists prefer the synonymous names Quercetalia roboris Tüxen 1931 and Quercetalia pubescenti-petraeae Klika 1933 for the mentioned orders.

As is customary in plant sociology , all units are characterized by types of character , also called characteristic types. For plant communities in the rank of order, these are the order character types. For newly described orders, the specification of order character types is mandatory. Differential types are also used to characterize them , which also occur in other syntaxa, but whose occurrence or absence in a certain order helps to distinguish them from related orders. In most cases, orders can be better characterized by their character types than associations or even associations. The character types of subordinate syntaxa, i.e. of the associations of order and their associations, are usually not order character types, since they only occur in a part of the units. However, orders are allowed that only include a single association, in which case the order and association characteristics coincide. As in the standard plant-sociological method, the character types are determined by arranging vegetation images in vegetation tables, but these are often aggregated into so-called continuity tables in the higher-ranking units.

The ranking of the order corresponds to the FGDC classification scheme common in North America, roughly the "group". Confusingly, the FDGC also uses the term “order”, which is defined differently and would correspond more to the European formation. To other classifications based on biotope types or habitat types , such as the EUNIS system, there are many relationships at the regulatory level, but no direct correspondence.

The number of different orders is understood differently by different vegetation experts. In a European overview, the EuroVeg Checklist project, 300 orders were distinguished for European vegetation. The founder of the method, Josias Braun-Blanquet, distinguished only 35 orders in the lowlands plus 20 in the mountains in Central Europe in 1951. Although outdated, the Oberdorfer system is still widely used in Germany.

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  • HE Weber, J. Moravec, J.-P. Theurillat (2000): International Code of Phytosociological Nomenclature. 3rd edition. Journal of Vegetation Sciencel 1: 739-768.
  • Josias Braun-Blanquet: Plant Sociology: Basics of Vegetation Science. 3rd edition, Springer Verlag, 1964 (new edition 2013). ISBN 978 3 7091 8110 2 , definition on pages 130–131.
  • Otti Wilmanns: Ecological Plant Sociology. Quelle & Meyer Verlag, Heidelberg, 3rd edition 1984. (UTB for science 269). ISBN 3 494 02027 2 .

Web links

Individual evidence

  1. ↑ FGDC Federal Geographic Data Committee (2008): National Vegetation Classification standard, version 2. FGDC-STD- 005-2008. Vegetation Subcommittee, US Geological Survey, Reston, Virginia, USA. PDF
  2. ↑ EuroVeg Checklist. University of Göttingen, Department of Vegetation Analysis & Phytodiversity, 2018.
  3. ↑ Ladislav Mucina et al. (2016): Vegetation of Europe: hierarchical floristic classification system of vascular plant, bryophyte, lichen, and algal communities. Applied Vegetation Science 19 (Supplement 1): 3-264. doi: 10.1111 / avsc.12257
  4. ↑ J. Braun-Blanquet (1951): Plant sociological units and their classification. Vegetatio 3 (1/2): 126-133.