Alnus glutinosa – dominated wetland forests of the Baltic Region: community structure, syntaxonomy and conservation

Abstract

Community structure, syntaxonomy and conservation aspects of Alnus glutinosa-dominated forests in the Baltic States, Central Europe, southern Fennoscandinavia and north-western part of the Commonwealth of Independent States are surveyed. Communities of the black alder wetlands, subjected to cluster analysis (TWINSPAN, GROUPAGE) and correspondence analysis (CANOCO) and synsystematically treated following the Braun-Blanquet approach, belong to Alnion (Carici elongatae-Alnetum Schwick. 33 with two subassociations, Sphagno squarrosi-Alnetum Sol.-Gorn. ex Pried. 96) and Alno-Ulmion (mainly Circaeo-Alnetum Oberd. 53) forests in the Baltic Region. The indicator values sensu Ellenberg, site ecology, floristic assemblages and the phytogeographical features point at a high affinity of these forests in a wide geographical area. Eleven syntaxonomical approaches by classifying central and north-eastern European alderwoods have been analysed. These differ in Alnion classification and distinguish from 2 to more than 10 syntaxa at the level of association. The actual distribution of less disturbed black alder wetlands and areas under these forests in Europe suggests that the SE part of the Baltic Region could be the key area for Alnus glutinosa-dominated wetlands. Thus, it deserves an establishment of an international network of standard protected areas so as to maintain the diverse community samples and elaborate the principles of sustainable management. Abbreviations: In figures CLT PALU means Caltha palustris, CAL PALU – Calla palustris. Abbreviations of all other species follow first 3 and 4 letters of the genus and species name, respectively. Nomenclature: Tabaka et al. (1988) for vascular plants, Abolina et al. (1984) for mosses.