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.
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.
Hampus von Post (1842, 1862),[6] Ragnar Hult (1881, 1898),[7] Thore Christian Elias Fries (1913),[8] Gustaf Einar Du Rietz (1921).
[5] 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.
Modern phytosociology for largely follows the work of Józef Paczoski in Poland, Josias Braun-Blanquet in France and Gustaf Einar Du Rietz in Sweden.
In Europe this information is generally mapped per 2 km² blocks for conservation purposes, such as monitoring particularly endangered habitat types, predicting success of reintroductions, or estimating more specific carrying capacities.
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.
[21] The basic unit of syntaxonomy, the organisation and nomenclature of phytosociological relationships, is the "association", defined by its characteristic combination of plant taxa.
The most important workers to define the modern system were initially Charles Flahault, with the work of his student Josias Braun-Blanquet being the what is generally considered the final version of syntaxonomical nomenclature.
Another type of mesotrophic pasture dominated by black knapweed (Centaurea nigra) and the grass Cynosurus cristatus, which is also widespread in western Europe, is consequently named Centaureo-Cynosuretum cristati Br.-Bl.
If the second species is characteristic but notably less dominant than the first one, its genus name may be used as the adjective,[23] for example in Pterocarpetum rhizophorosus, a type of tropical scrubland near water which has abundant Pterocarpus officinalis and significant (though not overwhelmingly prominent) red mangrove (Rhizophora mangle).
[24] 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 superorganismic framework.
Phytosociological data contain information collected in relevés (or plots) listing each species cover-abundance values and the measured environmental variables.
Further patterns are investigated using clustering and resemblance methods, and ordination techniques available in software packages like CANOCO[30] or the R-package vegan.