Vegetation

Due to their complexity, vegetation phenomena are not understandable without a consistent conceptual framework. A few indispensable concepts to explore the northeastern Portuguese ultramafic vegetation are set out in Tables 9 and 10. Association. The Phytosociology fundamental abstract unit is the association or associatio. The concept of association comprises an ecological-taxonomic model of the reality. Therefore, the association includes the notion of a plant community (biological information: floristic, physiognomic etc.) that occupies a particular biotope (chorologic information) where a specific set of environmental conditions can be found, i.e. the habitat (environmental information). The taxonomic element is mainly supported on the floristic composition, which is characteristic and statistically constant between associations. The development of a hierarchical syntaxonomic system (synsystem) is based above all on floristic, but also on environmental, biogeographic and physiognomic characters. Although the association concept is not a true synonym of phytocoenosis the two terms are often used interchangeably, which may result abusive