The effects of grazing rest on rangelands are different in different climates and knowledge of these effects is necessary to apply correct management. For this purpose, this study was carried out on the percent vegetation cover (PVC) and forage production (FP) of range species at the Nir Range Research Station in Yazd province as a model of steppe rangelands of Iran. In the study area, different grazing intensities were applied until the end of the grazing season of 2006 and from then on, the whole area was under exclusion. PVC and FP were measured in each of the experimental plots once in May 2007 and again seven years later in May 2014. The results of vegetation data analysis in 2007 showed that the heavy grazing intensity applied in the past caused the reduced PVC and FP of two desirable species i.e. Salsola rigida and Stipa barbata as well as increased PVC and FP of Launaea acanthodes and increased forage production of Scariola orientalis as undesirable species. The results of vegetation data analysis in 2014 showed that the lowest PVC and FP of S.rigida was recorded in the experimental plots under heavy grazing intensity. In other experimental plots, there was no significant difference in PVC and FP of this species (p>0.05). There was no significant difference between PVC and FP of other species and total species in different experimental plots (p>0.05). Thus, during the 7-year rest period, although the negative effect of grazing on S.barbata is resolved, it remains on S.rigida and the resulting degradation is not completely compensated during this period and needs more time. Therefore, S.barbata showed better resistance to grazing as compared with S.rigida. According to the results, if steppe rangelands are grazed heavily in the short-term, intermediate-term grazing rest could improve the vegetation to the previous state. Manuscript profile

Knowledge of the Saxaul dimensions used in sand dunes stabilization is considered essential for designing live windbreak in desert regions. This research aimed to collect and analysis data and was performed on the pruned and control shrubs of Haloxylon aphyllum L. in Yazd province, Iran in the last two decades. Our review clearly showed the superiority of shrubs pruned at the height of 35 cm in comparison with the other treatments as well as the superiority of soil surface height pruning with shoot thinning in the first year as compared with the other years. In the present study, data of canopy diameter and height of Haloxylon aphyllum L. from three treatments including "35 cm height pruned method", "shoot thinning method" and "control" were collected and analyzed using a completely randomized block design with three replications over 7 years (1995 to 2000 and 2005). Results of this study showed that the maximum canopy diameter of shrubs was obtained in the 35 cm height pruned method and soil surface pruning plus shoot thinning method with the average values of 261 and 240 cm, respectively with no significant differences. In addition, no significant difference was found for their heights (164 and 174 cm) and the dimension of pruned shrubs never reached to the height that was obtained before pruning. It was concluded that in designing the live windbreak with Haloxylon aphyllum L., considering the normal dimension of 35 cm height pruned shrubs at the executive levels as a practical pruning method is of high importance. Manuscript profile