In: Phyton, 49 Fasc. 1 (2009), S. 9-23 with 2 figures

Key words: Alnenion glutinoso-incanae, Hedero helicis-Alnetum glutinosae, alluvial forest, floodplain vegetation, phytosociology, vegetation science. – Alnus glutinosa. – Alto Adige, South Tyrol, Italy.

Summary

Wallnöfer S. 2009. A new Alnion incanae-association of the inner Italian Alps: Hedero helicis-Alnetum glutinosae. – Phyton (Horn, Austria) 49 (1): 9–23, with 2 figures.

In this study, the Hedero helicis-Alnetum glutinosae (Alnenion glutinoso-incanae, Alnion incanae) is newly described on the basis of phytosociological relevés. The forest type dominated by black alder is found in the colline and submontane belt on south-facing slopes in the inneralpic, precipitation-poor Vinschgau Valley (South Tyrol, Northern Italy). It colonizes banks of rivulets with shallow to intermediate soil depth. In the understory widespread species of deciduous forests and species of nutrient-rich sites dominate. A tabular comparison with Central European alluvial forest types rich in Alnus glutinosa (Pruno-Fraxinetum, Stellario nemorum-Alnetum glutinosae, Carici remotae-Fraxinetum) shows clear floristic differences. Differential species of the Hedero helicis-Alnetum glutinosae include thermophilous species; it is also negatively differentiated by the absence of species indicating wet soil and of the trees Fraxinus excelsior and Prunus padus. Also from the association of alluvial black alder forests in Northern and Central Italy (Aro italici-Alnetum glutinosae) the Hedero helicis-Alnetum glutinosae is clearly distinguished, inter alia by the absence of species preferring wet soils. However, by the dominance of Hedera helix it resembles generally the South European alluvial forests. Besides, floristic affinity to Carpinion-communities of Insubria exists. Because of the restricted distribution area and the smallness of the stands the Hedero helicis-Alnetum glutinosae must be considered as an endangered plant community.