Mountain vegetation of south-facing slopes in continental West Greenland
Drees, Birgit; Daniëls, Fred J. A.
Based on 143 relevés, mountain vegetation on south-facing slopes in continental West Greenland is analysed according to the Braun-Blanquet approach. Plant communities, their characteristic habitat conditions as well as their microtopographical and altitudinal distribution pattern are presented. This study completes a comprehensive regional survey of arctic vegetation and their altitudinal zonation in this part of Greenland (AZV Project). On south-facing slopes arctic steppe and associated vegetation types cover large areas and considerably enhance the biodiversity of the region. These thermoxerophytic vegetation types are assigned to the new class Saxifrago tricuspidatae-Calamagrostietea purpurascentis that for the present encompasses the following syntaxa: Arabido holboellii-Caricetum spaniocarpae (including two newly described subassociations), Carici spaniocarpae-Salicetum glaucae ass. nov., Saxifrago tricuspidatae-Dryopteridetum fragrantis ass. nov., and an Arctostaphylos uva-ursi community. Habitats are characterized by a distinct continental climate with intense insolation and high evapotranspiration in summer. The circumneutral soils have a silty to sandy texture and low organic matter contents. The geographical distribution range of the Saxifrago-Calamagrostietea comprises the low-arctic continental parts of the North American continent ranging from the East Greenlandic to the North Alaskan floristic subprovince. Species and communities show clear differentiations along the altitudinal gradient e. g. in occurrence, abundance or distribution pattern and thus are used for identifying borderlines between altitudinal vegetation belts. On southfacing slopes, plant communities with limited altitudinal distribution range are particularly suitable for this purpose. Here, based on floristic and vegetation characteristics, four altitudinal vegetation belts (e-b) are distinguished with borderlines at 450, 850 and 1250 m a. s. l. Fundamental differences with regard to flora, vegetation and their altitudinal differentiation were found between south- and north-facing slopes.