Effect of integrated fire period and intensity grazing on plant species diversity in the semi-steppe rangeland of chaharmahal and bakhtiari province

This study was was don to investigate the interaction  of fire and grazing effects on index of vegetation diversity in Semi-steppe rangelands in Chaharmahal - Bakhtiari Province.Therefore, 16 sites was selected with different periods of fire and grazing intensity and 18 quadrates along transects at each site were determined and then a systematic -random sampling method was don. Then, species diversity and Beta diversity indices were calculated. To determine the effects of fire, grazing, number of year and their interactions on the diversity indices, the method of General Linear Model (GML) and for determining the significant effect between fire site and unfired site the method of T- Test was used. The results showed that in areas with moderate grazing intensity and with different periods time of fire, Diversity, Simpson, Shannon and species richness indices, compared to control areas significantly increased. But beta diversity has decreased. Simpson's and Shannon Index compared to control areas significantly increased, in areas with high grazing and different time periods of fire, and in areas with 1-3 and 3-5 years fire, Species Richness was increased and decreased respectively. Also with different time periods of fire, beta diversity was decreased. Despite the restoration of some shrub species with the passage of time at burned areas, Compared to control, the grazing intensities was significantly decreased and the highest percentage of perennial grasses coverage was observed in fire areas in places with moderate grazing intensity. After the fire, appropriate management methods in Semi-Steppe Rangelands, can increase the Forage quality and also cause an increase in species richness.