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Phytosociology, also known as phytocoenology or simply plant sociology, is the study of groups of species of plant that are usually found together. Phytosociology aims to empirically describe the vegetative environment of a given territory. A specific community of plants is considered a social unit, the product of definite conditions, present and past, and can exist only when such conditions are met. In phyto-sociology, such a unit is known as a phytocoenosis (or phytocoenose). A phytocoenosis is more commonly known as a plant community, and consists of the sum of all plants in a given area. It is a subset of a , which consists of all organisms in a given area. More strictly speaking, a phytocoenosis is a set of plants in area that are interacting with each other through competition or other ecological processes. Coenoses are not equivalent to , which consist of organisms and the physical environment that they interact with. A phytocoensis has a distribution which can be mapped. Phytosociology has a system for describing and classifying these phytocoenoses in a hierarchy, known as syntaxonomy, and this system has a nomenclature. The science is most advanced in Europe, Africa and Asia.

In the United States this concept was largely rejected in favour of studying environments in more individualistic terms regarding species, where specific associations of plants occur randomly because of individual preferences and responses to gradients, and there are no sharp boundaries between phytocoenoses. The terminology '' is usually used in the US for a habitat consisting of a number of specific plant species.

It has been a successful approach in the scope of contemporary vegetation science because of its highly descriptive and predictive powers, and its usefulness in nature management issues.


History
The term 'phytosociology' was coined in 1896 by Józef Paczoski.Rabotnov TA. 1970-1979. Phytocoenology. In: The Great Soviet Encyclopedia, 3rd ed. The term 'phytocoenology' was coined by in 1918. While the terminology phytocoenosis grew to be most popular in France, Switzerland, Germany and the Soviet Union, the terminology phytosociology remained in use in some European countries.

Phytosociology is a further refinement of the introduced by Alexander von Humboldt at the very beginning of the 19th century.Humboldt, A. von & Bonpland, A. 1805. Essai sur la geographie des plantes. Accompagné d'un tableau physique des régions équinoxiales fondé sur des mesures exécutées, depuis le dixiéme degré de latitude boréale jusqu'au dixiéme degré de latitude australe, pendant les années 1799, 1800, 1801, 1802 et 1803. Paris: Schöll, [2].Alexander von Humboldt (1806). Ideen zu einer Physiognomik der Gewächse. Tübingen: Cotta, [3]. English translation as Ideas for a physiognomy of plants, pp. 210-352 in Views of nature: or Contemplations on the sublime phenomena of creation by E.C. Otté and Henry G. Bohn (1850). London: H.G. Bohn, [4].Decocq, G. (2016). Moving from Patterns to Processes: A Challenge for the Phytosociology of the Twenty-First Century? In: Box, E. O. (Ed.). Structure and Function at Multiple Spatial, Temporal and Conceptual Scales. Springer. pp. 407-424

Phytocoenology was initially considered to be a subdiscipline of 'geobotany'.

In the concept of plant associations was popular at an early date. Hampus von Post (1842, 1862), (1881, 1898),Hult, Ragnar (1881). Försök till analytisk behandling af växtformationerna ("Attempt at an analytic treatment of plant communities"). Meddelanden af Societas pro Fauna et Flora Fennica, 8, pp. 1–155. Doctoral dissertation (University of Helsinki). Full text. Thore Christian Elias Fries (1913),Fries, T.C.E. (1913). Botanische Untersuchungen im nördlichsten Schweden. Ein Beitrag zur Kenntnis der alpinen und subalpinen Vegetation in Torne Lappmark. Akademische Abhandlung. Vetenskapliga och praktiska undersökningar i Lappland. Flora och fauna Nº 2, p. 1-361, [7]. Gustaf Einar Du Rietz (1921).Du Rietz, G.E. (1921). Zur methodologischen Grundlage der modernen Pflanzensoziologie. Akadem. Abh. Upsala (Thesis, Uppsala), 272 pp.

  • Rübel (1922, 1930),Rübel, E.F. (1922). Geobotanische Untersuchungsmethoden. Gebrüder Borntraeger, BerlinRübel, E.F. (1930). Pflanzengesellschaften der Erde. Bern-Berlin: H. Huber, [9]. Pavillard (1927),
  • Schröter & Kirchner (1886–1902),Schröter, C. & Kirchner, O. 1886–1902. Die Vegetation des Bodensees. Stettner, Lindau, DE Flahault & Carl Joseph Schröter (1910),Flahaut, C. & Schröter, C. (1910). Phytogeographische Nomenklatur. Berichte und Worschläge. IIIe Congrès International de Botanique, Bruxelles, 14–22 mai. Zürcher & Furrer, Zürich, CH.

In the /ref>

The science of phytosociology has hardly penetrated into the English-speaking world, where the continuum concept of community prevailed, opposed to the concept of a 'society' of plants. Nonetheless it had some early adherents in the United States, notably Frederic Clements in particular, who used the concept to characterise the vegetation of California. Largely following European ideas, he devised his own system to classify habitat types using vegetation.Clements, F.E. (1905). Research Methods in Ecology. Lincoln, Neb.,University Pub. Co., [11].Clements, F.E. 1916. Plant Succession. Publication 242, Carnegie Institute, Washington, DC. Clements most important contribution was his study of succession. His work has seen much local usage. In Britain was the first to apply phytosociological concepts to the vegetation of the kingdom in 1911 after learning of its application elsewhere in Europe.Tansley, A.G. (Ed). 1911. Types of British Vegetation: by Members of the Central Committee for the Survey and Study of British Vegetation. Cambridge University Press. Cambridge, [12]. Tansley eventually broadened the concept and thus came up with the idea of an , combining all biotic and abiotic ecological aspects of an environment. The work of Tansley and Clements was quite divergent from the rest.


Usage today
Modern phytosociology largely follows the work of Józef Paczoski in Poland, Josias Braun-Blanquet in France and Gustaf Einar Du Rietz in Sweden.

In Europe a complete classification system has been developed to describe the vegetation types found across the continent. These are used as habitat-type classifications in the NATURA 2000 network and in Habitats Directive legislation. Each phytocoenose has been given a number, and protected areas can thus be classified according to the habitats they contain. In Europe this information is generally mapped per 2 km² blocks for conservation purposes, such as monitoring particularly endangered habitat types, predicting success of , or estimating more specific carrying capacities. Because certain habitats are deemed more imperilled (i.e. having a higher conservation value) than others, a numerical conservation value of a specific site can be approximated.


Overview
The aim of phytosociology is to achieve a sufficient empirical model of vegetation using combinations of plant species (or subspecies, i.e. ) that characterize discrete vegetation units. Vegetation units as understood by phytosociologists may express largely abstract vegetation concepts (e.g. the set of all hard-leaved of western area) or actual readily recognizable vegetation types (e.g. cork-oak oceanic forests on dunes with dense canopy in Iberian Peninsula). Such conceptual units are called syntaxa (singular "syntaxon") and can be set in a hierarchy system called "synsystem" or syntaxonomic system. Creating new syntaxa or adjusting the synsystem is called syntaxonomy. Before the rules were agreed upon, a number of slightly different systems of classification existed. These were known as "schools" or "traditions", and there were two main systems: the older Scandinavian school and the Zürich-Montpellier school,Sharma, P. D. (2009). Ecology and Environment. Rastogi: Meerut, p. 140-142, [13]. also sometimes called the Braun-Blanquet approach.
(2025). 9780080454054, Academic Press.


Relevé
The first step in phytosociology is gathering data. This is done with what is known as a relevé, a plot in which all the species are identified, and their abundance both vertically and in area are calculated. Other data are also recorded for a relevé: the geographic location, environmental factors and vegetation structure. and (formerly) tables are used to sort the data. As the calculations needed are difficult and tedious to do manually, modern ecologists feed the relevé data into software programs that use algorithms to crunch the numbers.


Association model
The basic unit of syntaxonomy, the organisation and nomenclature of phytosociological relationships, is the "association", defined by its characteristic combination of plant taxa. Sometimes other habitat features such as the management by humans (mowing regime, for example), and/or the stage in ecological succession may also be considered. Such an association is usually viewed as a discrete phytocoenose. Similar and neighbouring associations can be grouped in larger ecological conceptual units, with a group of plant associations called an "alliance". 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.

The most important workers to define the modern system were initially , with the work of his student Josias Braun-Blanquet being the what is generally considered the final version of syntaxonomical nomenclature. Braun-Blanquet further refined and standardised the work of Flahault and many others when he worked on the phytocoenosis of the southern Cévennes. He established the modern system of classifying vegetation.Nicolson, M. (1993). National Styles, Divergent Classifications: A comparative case study from the history of French and American plant ecology. Knowledge and Society: Studies in the Sociology of Science Past and Present, 8, 139-186. Braun-Blanquet's method uses the of its most characteristic species as namesake, changing the ending of the to "- etum" and treating the as an . Thus, a particular type of grassland widespread in western Europe and dominated only by the grass Arrhenatherum elatius becomes " Arrhenatheretum elatioris Br.-Bl.". To distinguish between similar plant communities dominated by the same species, other important species are included in the name, but the name is otherwise is formed according to the same rules. Another type of mesotrophic dominated by black knapweed ( ) and the grass Cynosurus cristatus, which is also widespread in western Europe, is consequently named Centaureo-Cynosuretum cristati Br.-Bl. & Tx.. If the second species is characteristic but notably less dominant than the first one, its genus name may be used as the adjective,Braun-Blanquet, J. (1932). Plant sociology; the study of plant communities. New York and London, McGraw-Hill for example in Pterocarpetum rhizophorosus, a type of near water which has abundant Pterocarpus officinalis and significant (though not overwhelmingly prominent) red mangrove ( Rhizophora mangle).

Today an International Code of Phytosociological Nomenclature exists, in which the rules for naming syntaxa are given. Its use has increased among botanists.

In Anglo-American ecology, the association concept is mostly linked to the work of the mid-twentieth century botanist Henry Gleason, who set it up as an alternative to Frederic Clement's views on the .See, for example: "Nature's Economy: A History of Ecological Ideas" by Donald Worster, Cambridge University Press, 1994. The philosophical parameters of the association concept have also come under study by environmental philosophers as to how it values and defends the natural environment.See, for example: "The Unity of Nature: Wholeness and Disintegration in Ecology and Science" by Alan Marshall, Imperial College Press/WorldScientific, 2002


Vegetation complexes
Modern phytosociologists try to include higher levels of complexity in the perception of vegetation, namely by describing whole successional units (vegetation series) or, in general, vegetation complexes. Other developments include the use of multivariate statistics for the definition of syntaxa and their interpretation.


Data collections
Phytosociological data contain information collected in relevés (or plots) listing each species cover-abundance values and the measured environmental variables. This data is conveniently databanked in a program like TURBOVEG allowing for editing, storage and export to other applications.

Data is usually classified and sorted using TWINSPANHill MO (1979) TWINSPAN: A FORTRAN Programme for arranging multivariate data in an ordered two-way table by classification of the individuals and attributes. Ecology and Systematics, Cornell University, Ithaca, NY in host programs like JUICE to create realistic species-relevé associations. Further patterns are investigated using clustering and resemblance methods, and ordination techniques available in software packages like CANOCOter Braak CJF, Šmilauer P (2002) CANOCO Reference manual and CanoDraw for Windows User’s guide: Software for Canonical Community Ordination (version 4.5). Microcomputer Power, Ithaca, NY or the R-package vegan. PDF


See also


External links

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