Phytosociology

Phytosociology is the branch of science which deals with plant communities, their composition and development, and the relationships between the species within them. A phytosociological system is a system for classifying these communities.

Rooted in phytogeography and as such considered sometimes a field of geobotany, phytosociology emerged simultaneously in Poland (Paczoski), France (Braun-Blanquet) and Sweden (Du Rietz), but hardly penetrated in Anglo-Saxon world, where prevailed the continuum concept of community, opposed to the concept of plant associations.

The term "phytosociology" was coined in 1896 by Paczoski.

There are five classification schools in phytosociology:

The aim of phytosociology is to achieve a sufficient empirical model of vegetation using plant taxa combinations that characterize univocally vegetation units. Vegetation units as understood by phytosociologists may express largely abstract vegetation concepts (e.g. the set of all hard-leaved evergreen forests of western Mediterranean area) or actual readily recognizable vegetation types (e.g. cork-oak oceanic forests on dunes with dense canopy in SW-Iberian Peninsula). Such conceptual units are called "syntaxa" (singular "syntaxon") and can be set in a hierarchy system called "synsystem" or syntaxonomic system. The act of creation, amelioration or adjusting the synsystem is called "syntaxonomy". Therefore, the syntaxonomic system is putatively a sufficient empirical representation of vegetation of a given territory. An International Code of Phytosociological Nomenclature, issuing the rules for naming "syntaxa" exists and its use has increased among vegetation scientists.

The basic unit of syntaxonomy is the "association", defined by its characteristic combination of plant taxa, habitat features, physiognomy, biogeographical area, role in ecological succession, historical (e.g. history of use by humans) and paleo-biogeographical relationships. The association is sometimes viewed as a concrete phytocoenosis (the plant component of a biocoenosis). Associations with floristic and territorial affinities can be grouped in larger ecological conceptual units (i.e. syntaxa) called "alliances". Similar alliances may be grouped in "orders" and orders in vegetation "classes". The setting of syntaxa in such a hierarchy makes up the syntaxonomical system, or the reference model of the given vegetation and territory.

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