The production variability and energy equivalent of the Carex pilosa population biomass were analyzed in association Carici pilosae-Fagetum O b e r d. 1957 on a clear cutting area (consortium of Fagus sylvatica reserve) of the Ecological Experimental Station Kremnicke vrchy Mts. The selected species is a dominant species of the studied association. The biomass of juvenile daughter ramets was highest in September (1,112.75 kg.ha-1) and the lowest one in May (172,66 kg.ha-1). The highest average energy value of the Carex pilosa juvenile ramets was in June (18 107 J.g-1) and the lowest one was measured in August (17 884 J.g-1). The annual growth increment (C-production) was 940.09 kg.ha-1.year-1, in energy units it represents 16,953 GJ.ha-1.year-1. The correlation analysis showed weak relationship between the energy equivalent and aboveground biomass of Carex pilosa species.