Evaluation of temporal variations of Astragaluseffusus yield and consumption in semi-steppe rangelands of Uromieh

ABSTRACT: Every range species has given yield in different grazing season and years. Also individual livestock’s consume given forage in each temporal and spatial scale of grazing season. It is impossible to planning and managing livestock and rangeland in case of no knowledge of plants yield and consumption characteristics. Asrtagalus effusus serves as one of the important range species ofUromieh County. To evaluate dealing with this species vegetative and yields characteristics and its consumption rate in different phenologies by livestock’s, the present research was conducted for four years (2007-2010) in Gharebagh regions of Uromieh. for this, as grazing season starts and livestock’s enter into rangelands, the amount of forage remained after grazing until removing livestock’s from rangelands was harvested in monthly intervals and species use rate (exploitation) is determined by subtracting it from yield within plots. These data evaluated in order to address effect of study years and harvesting months on species yield and consumption. Results of data mixed variance analysis showed significant difference among different months so that the highest yield and consume rates of 1.77 and 1.64 gr/stand might occurred in the fourth year. For six months, the highest yield and consumption rates of 4 and5.12 gr/stand were in May. Under present research condition, presumably precipitation might be a determinant factor to increase this species production and consumption.