|Löbel, S; Dengler, J: Dry grassland communities on southern Öland: phytosociology, ecology, and diversity. In: van der Maarel, E. [Ed.]: Structure and dynamics of alvar vegetation on Öland and some related dry grasslands – Dedicated to Ejvind Rosén on his 65PthP birthday., Acta Phytogeographica Suecica, 88, 13-32 (2008)|
|Key words: Alvar; Biodiversity; Environmental condition; Festuco-Brometea; Koelerio-Corynephorenea; Sedo- Scleranthenea; Species richness; Syntaxonomy|
We studied dry grassland vegetation on southern Öland, both within and outside the Great Alvar, using the Braun- Blanquet approach. We were able to distinguish 15 as- sociations or equivalent units belonging to three major syntaxa. Dry grasslands on sandy soils (class Koelerio- Corynephoretea; subclass Koelerio-Corynephorenea) occurred along the east and west coasts. Weathered rock and outcrop communities (class Koelerio-Corynephoretea; subclass Sedo-Scleranthenea) inhabited shallow skeletal soils, mainly on the Great Alvar. Semi-dry basiphilous grasslands of the class Festuco-Brometea occurred on moraine soils, which were the least extreme in terms of soil moisture and nutrient availability. Whereas the first category comprises impoverished variants of widely distributed syntaxa, all Sedo-Scleranthenea and Festuco- Brometea communities lack direct counterparts in central Europe. The alvar communities proved to be floristically well separated from the others. Species density on 4 m2 was highest in the Sedo-Scleranthenea (that of the Gypsophilo fastigiatae-Globularietum vulgaris with 80 taxa being one of the highest known), intermediate in the Festuco- Brometea, and lowest in the Koelerio-Cory e n phorenea. Harsh and variable conditions, small plant sizes, and a large local species pool are considered possible causes.