Exclusion and not using of rangeland in the long term affects the composition and homogeneity of vegetation and consequently leads to the improvement of plants status. In this study, the characteristics and structural changes of the rangeland of Gonbad, Hamadan province, Iran, in 2014 (after 20 years of enclosure) were evaluated using Braun-Blanquet plot, Phytosociology and multivariate analysis by the software PC-Ord5. According to clustering diagram and Indicator Species Analysis, it was found that the studied region had 10 vegetation types and 17 Indicator Species. Detrended Correspondence Analysis (DCA) showed that in the first axis the variables: stone and gravel percentage, Electrical Conductivity (EC), clay, and organic carbon were important and in the second axis canopy cover of grasses, total canopy cover, and pH were important. Principal Component Analysis (PCA) confirmed the relationship between plant communities and environmental factors in the enclosure region. It was found that there are correlations between the echo logical units and the factors: stone and gravel (0.25), clay (-0.26), sand (0.28), silt (0.38), slope (-0.36), total neutralizing value (0.34), and plant species indicators that resulted to the separation of the units. The results showed that in the long-term enclosure, plant communities tend towards a uniform and homogeneous composition and consequently led to the improvement of the rangeland vegetation conditions. Therefore the density, composition and the class I plant species have increased. پرونده مقاله

Fire causes extensive damage to rangelands’ ecosystems in arid and semi-arid regions. The purpose of this study was to investigate the effects of rangeland fire on vegetation and forage production in mountainous rangelands of the Solan area in Hamadan province, Iran. A burnt area and a homogeneous area without fire (control) were selected for this study. In the burnt area, the fire has occurred in July 2018. In each site, data were collected in the months July to October using four linear transects with a length of 200 m using a systematic random sampling method. In each transect at a distance of 20 m, 10 plots of 1m2 were considered. Vegetation sampling was done during (July to October) three years of 2018, 2019, and 2020. Some factors such as forage production, percentage of bare soil, stones and gravels, litter, survival rate, canopy cover, and percentage of shrubs, perennial and annual forbs, perennial and annual grasses were measured. The results showed that there were significant differences between the two areas for all variables except perennial forbs cover, shrubs cover, and stone and gravels percent in the first year. Fire reduced the litter percent, forage production, canopy cover, survival, and increased bare soil, soil erosion, and sediment. The geophytes life forms of the species in the study areas had the highest coverage percentage (38.66%) in both areas. Some species such as: Astragalus verus, Astragalus gossypinus, Acantholimon bromifolium, Acantholimon olivieri, and Acanthophyllum crassifolium were sensitive to fire. On the other hand, species such as Rosa persica due to having rhizomes and extensive underground roots were resistant to fire. پرونده مقاله