Abstract
The study presents phytosociological and ecological data from azonal black alder forest sites in the southern part of central Slovakia. A data set of 29 relevés was collected by authors in vegetation season 2010 following the standard Braun-Blanquet approach. Numerical classification was performed to delimit the main vegetation types, while statistical analyses were applied to explain the vegetation-environmental relationships. Three associations within two classes were distinguished using a TWINSPAN algorithm. Carici elongatae-Alnetum glutinosae Schwickerath 1933 is an alder carr forest occurring on waterlogged soils in spring fed areas and alluvial zones along rivers. Carici acutiformis-Alnetum glutinosae Scamoni 1933 represents an alder carr forest on habitats with stagnant or slowly flowing water along water courses and artificial water reservoirs. Mesic to humid stands along small brooks are typical for the riparian alder vegetation of Stellario-Alnetum glutinosae Lohmeyer 1957. A detailed description of the floristic and ecological features of these associations is presented. The major environmental gradients affecting variation in species composition of these communities were interpreted as a response of vegetation to soil moisture and nutrient availability regarding the Ellenberg indicator values (moisture and nutrients) and measured variables (total N and C).