Vegetation of hygrophilous herblands of shallow montane pools characterised by large water-depth fluctuations at high altitudes of Sicily
Alopecuro-Glycerion spicatae S. Brullo et al. 1994
Alopecuro-Glycerion spicatae S. Brullo et al. 1994
phr11 | The Alopecuro-Glycerion spicatae was described from the ponds and lakes of the Nebrodi Mts, Sicily. Brullo et al. (1994) justified the delimitation of this alliance by a peculiar species composition being primarily a mixture of species of the Phragmito-Magnocaricetea and Potamogetonetea, with some other accompanying species straddling the Phragmito-Magnocaricetea and Molinio-Arrhenatheretea. This composition was ascribed to specific climatic conditions of Sicily characterised by high, yet uneven annual precipitation patterns. There are typical periods of summer drought accompanied by short heavy rains that becomes reflected in high water-level fluctuations in the ponds during the summer. Based on the large cover of the Potamogetonetea species in the Alopecuro-Glycerion communities, Brullo et al. (1994) classified the Alopecuro-Glycerion spicatae within the Potamogetonetea. However, most of sampled stands published in the original paper are dominated by Phragmito-Magnocaricetea species that determine the physiognomy of the stands. Therefore, we argue that the Alopecuro-Glycerion should be assigned to the Phragmito-Magnocaricetea. The communities of the Alopecuro-Glycerion, and many other types of reed vegetation alike, experience stages of drought and stages of floods with well-developed floating and/or submerged layer of aquatic plants. It appears that this alliance was coined on the basis of communities sampled during the periods of elevated water levels. The Alopecuro-Glycerion shares considerable floristic and ecological similarities with the Eleocharito palustris-Sagittarion sagittifoliae and partly also with the Glycerio-Sparganion characteristic of habitats with fluctuating water level and co-occurrence of numerous aquatic plants during the flooding phase. We consider, however, the status of the Alopecuro-Glycerion as insufficiently clear and therefore we prefer maintaining this unit as a separate alliance. As such, we classified this alliance, together with Eleocharito-Sagittarion, in the Oenanthetalia. This solution should be considered as preliminary as new relevé data should be collected in phases other than in time of flooding to shed light on the yearly dynamics of the floristic composition fo this vegetation. (K. Šumberová, L. Mucina).