The differentiation of alliances in South Sweden

Abstract

The main objective of the present study was to attempt to assign different vegetation types in South Sweden to the Braun-Blanquet system of syntaxa. The alliance was chosen as the most appropriate phytosociological unit for this purpose. Coniferous forests represent the zonal vegetation in large parts of South Sweden: spruce forests on mesic to moist sites and pine forests on dry, often strongly oligotrophic sites can be assigned to thePiceion excelsae andDicrano-Pinion respectively. In addition, various types of azonal vegetation (e.g., mires, springs, swamps and salt-marshes) subjected to some form of extreme environmental factor can be placed in alliances described from Central Europe. In contrast, some southern vegetation types in Sweden are difficult to assign, partly due to a lack of character species, as in the case of deciduous hardwood forests. In other cases, species of southern syntaxa are still frequent, for example in dry basiphilous grasslands and sun-exposed forest edges, but the syntaxonomical difficulties arise from an intermixture of diagnostic species of complementary alliances. This might be explained by the floristic and climatic conditions in South Sweden which deviate considerably from those in e.g. Germany a feature supported by the communities' indicator figures for temperature and continentality. This refers particularly to the combination of rather low average temperatures and, except in the west, a strong thermal or hygric continentality.