The present study deals with seasonal variation in productivity and nutritive value of dominant grassland species of Barh Diara, Bihar dominated by Cynodon dactylon. The thesis contains the results of studies made on phytosociological studies, standing crop biomass, primary productivity, turnover, energetics of primary production and nutritive value of dominant grassland species on protected and grazed grasslands of Barh diara, Bihar (250 29' N latitude, 850 45' E longitude, 46.99M m at the mean sea level). The field observations and sampling were carried out at regular intervals of one month in protected and grazed grasslands from June 2012 to June 2013.