Classification of Molinia meadows in Poland using a hierarchical expert system
Swacha, Grzegorz; Kącki, Zygmunt; Załuski, Tomasz
Aims: A hierarchical expert system provides an opportunity to perform a formalized classification of vegetation at different syntaxonomical levels. Creating formal definitions for higher vegetation units is quite new to vegetation science. This approach was used for the delimitation of high-rank vegetation units consisting of species occurring almost exclusively in that particular type of vegetation and rarely found elsewhere. No formal definitions have been published so far for higher vegetation units of the class Molinio-Arrhenatheretea. In this study we used a hierarchical expert system to classify one of the most complex and heterogeneous vegetation type from this class, namely Molinion alliance, which combines taxa from different habitats and vegetation units. Location: Poland Methods: The classification was carried out based on 53,541 relevés from the Polish Vegetation Database (PVD). We applied a formal definition of the alliance Molinion to a geographically stratified data set. The resulting set of 586 relevés formed a group of relevés representing Molinion meadows for further detailed delimitation of units at the level of association. Results: Using Cocktail definitions we delimited four associations belonging to the alliance Molinion and made the first attempt to create a formal definition of this alliance. We determined diagnostic species for each vegetation unit, both at alliance and association levels. The presented Cocktail definition of the alliance Molinion can be used for explicit identification of Natura 2000 habitat – Molinia meadows on calcareous, peaty or clayey-silt-laden soils (6410) in Poland. Conclusions: We consider creating formal definitions for higher vegetation units as the efficient way of delimiting broader vegetation types. Once the alliance group is defined, it becomes a reference data subset for a detailed classification of low-rank vegetation units (i.e.associations). Creating formal definitions for alliances also seems to be of fundamental importance in terms of nature conservation.