Effects of exclosure on some vegetative characteristics and distribution pattern of Artemisia sieberi in central steppes of Iran (Case study: Nodoushan rangelands of Yazd province)

Investigation on the vegetation cover of rangelands under grazing and exclosure conditions is important in improvement of range management. Therefore, this research was aimed to investigate the effect of exclosure on production, density, frequency, importance value and vitally of Artemisia sieberi as the most important species of steppe rangelands of Iran. The study was conducted in Nodushan rangelands of Yazd province under grazing and exclosure conditions. Sampling was done randomly in both grazing and exclosure areas, with 10 transects and 40 quadrates of 1m2. In addition, 30 individuals of Ar. sieberi were selected randomly in each area and plant height, maximum and minimum diameter, canopy caver, vitality and dry matter production were measured. According to the obtained results, the studied species showed no significant differences for production, average diameter, height and canopy cover percentage. However, the vitally of Ar. sieberi showed significant differences between grazing and exclosure areas. The results of importance value indicated the increased relative importance of Ar. sieberi under moderate grazing intensity. The distribution pattern of Ar. sieberi under exclosure was uniform while under grazing condition a clumped distribution pattern was observed.