preference value of three species for sheep in steppe rangelandsof iran

more than half of the area of the country are rangelands. implementing the principles of proper rangeland management and optimal use of rangeland requires proper stock grazing management. considering the quality and quantity of forage plants, palatability and preference value of species and rates of species utilization are information needed for proper management of livestock grazing in rangelands. in this study, preference value of three plant species of  steppic rangelands including of iran includingartemisia sieberi, stipa arabica and scariola orientaliswere considere. the studied sites are located in kerman, yazd and isfahan provinces. at first, the vegetation type of each site was determined and and its floristic list was prepared over spring and summer. the selection criteria were used in order to determine the value of preferred species. random sampling with the plot of one square meter was done in different months and factorial experiment in randomized complete block design was usedto compare preference values and their comparison in different times and places. the results showed that preference value between plant species and studied sites at five percent are significant but there was no significant difference among different months.the interaction of species and stage of grazing was not significant in this research. moreover, the preference value of stipa arabica andartemisia sieberi for sheep grazing were different over different months. the results also reveald that artemisia sieberi in nadooshan site has the highest preference value.