One of the main problems in modern agricultural production is the inefficient use and management of natural resources. The aim of the present study is to analyze the productivity and assess the species composition of natural pastures (Np) used for grazing by sheep in farms in the region of Central Northern Bulgaria. The observations were carried out in the period mid-April -  mid-June 2018-2019, at intervals of 14 days on eight natural grasslands located in the region of Central Northern Bulgaria. They are selected to cover the most typical and used natural pastures in the plains and semi-mountains of the region. The comparative assessment of the 8 plant populations of pasture type, subject of the present study, under the ecological conditions of Central Northern Bulgaria showed the highest yield of dry mass observed in the natural meadows in the plains - Np 4 (780.67 kg ha-1) , followed by Np 6 (760.09 kg ha-1) and Np 8 (740.24 kg ha-1), an average of 760.33 kg ha-1.

The grasslands from semi-mountains of the region (Np 1, 2 and 3), show a different reaction to the growing environment, but all of them are characterized  by significantly lower productivity of green and dry biomass (respectively 1310.77 kg ha-1 and 380.90 kg ha-1) compared to the grasslands of the plains (2430.72 kg ha-1 and 740.66 kg ha-1 respectively).

The green biomass yield from the natural pastures, object of study, ranges from 920.38 kg ha-1 (Np 2) to 3000.13 kg ha-1.

The dry mass yield is from 290.02 kg ha-1 (Np2) to 780.67 kg ha-1 (Np 4).