PICEA ABIES AND ABIES ALBA FORESTS OF THE AUSTRIAN ALPS: NUMERICAL CLASSIFICATION AND ORDINATION.

A TWINSPAN classification of a representative set of 3026 relevés of spruce and fir forests from the Eastern Alps (Austria) is presented. Ecological features of relevé clusters and species groups are described by means of Ellenberg indicator values, site factors and stand characteristics. The most important floristic discontinuity in the data set separates acidophilous communities on mostly silicate substrates from basiphilous communities on mostly carbonate substrates. Further divisions reflect a combined gradient of temperature, nutrient regime and shading. This is supported by the correlation of average Ellenberg values of sample plots with DCA axes. A qualitative comparison between TWINSPAN clusters and a syntaxonomic system widely used in the Austrian Alps is drawn. The two orders Piceetalia excelsae and Athyrio-Piceetalia largely coincide with the clusters of the first level of divisions. Alliances are partly reproduced by TWINSPAN. Clusters on the fifth and fourth level of division mostly correspond to associations. However, a considerable portion of the lower level clusters is of a transitional type. Out of thirteen fir and spruce associations described for the Austrian Alps, five associations are not reproduced by TWINSPAN, i.e. Bazzanio-Piceetum, Veronico-Piceetum, Adenostylo alliariae-Abietetum, Asplenio-Piceetum and Carici-Piceetum. Three associations are split on the second level of division, i.e. Larici-Piceetum, Luzulo nemorosae-Piceetum and Calamagrostio variae--Piceetum. [ABSTRACT FROM AUTHOR]