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). V članku so predstavljeni fitosociološki in ekološki podatki iz azonalnih gozdov črne jelše v južnem delu osrednje Slovaške. V vegetacijskem obdobju leta 2010 smo naredili 29 popisov po standardni Braun-Blanquetovi metodi. Z numerično klasifikacijo smo opredelili glavne vegetacijske tipe, s statističnimi metodami pa pojasnili povezavo med vegetacijo in okoljskimi dejavniki. Z algoritmom TWINSPAN smo ločili tri asociacije znotraj dveh razredov. V asociacijo Carici elongatae-Alnetum glutinosae Schwickerath 1933 uvrščamo jelševe greze na rastiščih z visoko talno vodo ob potokih in na aluvialnih ravninah ob rekah. Asociacija Carici acutiformis-Alnetum glutinosae Scamoni 1933 predstavlja jelševe gozdove na rastiščih z zastajajočo ali počasi tekočo vodo ob vodotokih in umetnih vodnih telesih. Mezofilni do vlažni sestoji ob majhnih potokih so značilni za asociacijo Stellario-Alnetum glutinosae Lohmeyer 1957. V članku so podrobno opisane floristična sestava in rastiščne značilnosti teh asociacij. Glavni ekološki gradienti, ki se kažejo v vrstni sestavi, so talna vlaga in hranila. Med Ellenbergovimi indikatorskimi vrednostmi sta to vlažnost in hranila, med merjenimi spremenljivkami pa skupni N in C.