The study of accumulation, concentration and reserves of phytomass by blocks of plant matter, balance of phosphorus, potassium, calcium in phytocenoses of the middle Mountain subprovince of Dagestan was carried out. The research was carried out in 2017 on the slopes of the southern and northern expositions of mount Mayak (1700 m n. a. m.) of the Gunib experimental base Of the mountain Botanical garden of the DSC RAS. There was a decrease in 2017 of indicators of accumulation of plant mass, concentrations of phosphorus, potassium, calcium and their reserves in the exposures of slopes compared to the previous 2012-2016. There was a slight increase in the concentration of phosphorus, potassium, calcium in phytomass in comparison with previous years, due to the accumulation and further decomposition of a large number of plant residues (dead phytomass   and litter), in connection with the protected mode of use of sites. The maximum amount of green phytomass (7.1 kg / ha*day), dead phytomass (14.2 kg / ha* day), steppe litter (6.2 kg/ha·day) and roots (75.6 kg/ha·day) accumulated on the southern slope of the middle Mountains of Dagestan. The concentration of chemical elements and their reserves in the aboveground and underground mass differed depending on the exposure of the slope. In green phytomass the highest concentration was potassium – 2,68-2,71, then calcium – 0,48-0,50, the lowest-phosphorus (0,08-0,09%). In dead phytomass, litter and roots, the concentration of calcium was higher than potassium and phosphorus.