One of the effective ways for reducing atmospheric CO2 is carbon sequestration by plants and soils. Rangelands with an expanded area have a great potential for Carbon (C) Stocks. In this study, C stocks in three treatments including natural rangelands (NR), Pit- seeding by Agropyrum elongatum (PS) and abandoned dry farming (ADF) were examined in Kardeh basin Mashhad, Iran in 2013. In each treatment, ten transects and in each transect, ten plots were established. Percentages of vegetation cover, litter, rock and soil were recorded in each plot. Aerial and root biomasses of dominant species were sampled by the clipping and weighing method. Litters in each plot were collected and weighed, too. Carbon content of biomass and litter were measured by combustion method using Electric Combustion Furnace. Ten soil samples were taken along each transect at two depths of 0-25 and 25-50 cm. The soil organic carbon percent was determined by the Walkley–Black method. Data analysis was performed by one-way analysis of variance (ANOVA) and means were compared using Duncan test. Results showed significant differences between treatments for total C stocks (soil+biomass+litter). NR and ADF management with the average values of 535.32 and 177.14 (t.ha-1) had the highest and lowest C stocks, respectively. Among the components of the ecosystem, soil had a main role in C sequestration followed by above biomass, roots and litters. PS management had the highest C stocks in plant biomass and litter but its soil C stocks were significantly lower than NR. Perennial grasses, bushes and perennial forbs were dominant in PS and NR management that play the most important role in plant C stocks. In conclusion, proper management of natural rangelands and more attention to vegetation and soil conservation may lead to store a considerable amount of C stocks in these lands. پرونده مقاله

Astragalus fridae Rech. F. is a native and endemic species in Iran. Considering the circumstances of this species in the country and the world and the importance of conservation of genetic resources, the awareness of A. fridae forage quality seems necessary. For this purpose, forage samples of A. fridae were taken at four phenological stages including vegetative growth, flowering, seed setting and maturity over three years (2012- 2014) in Semnan province, Iran. Forage quality factors such as DMD, CP, WSC, ADF, Ash, CF, NDF and ME were measured by NIR. Their overall means over phenological stages were 67.38%, 7.58%, 17.43%, 27.79%, 5.89%, 39.87%, 47.47% and 9.46mj/kg, respectively. Result of analysis of variance showed significant differences (P پرونده مقاله

Annual climate fluctuations cause changes in production, condition, trends and grazing capacity of rangelands. The present study investigated effect of climatic factors on the vegetation dynamics in Jashloobar, summer rangeland of Semnan province, Iran, in two vegetation types: Festuca rubra in Margesar and Stipa lessingiana in Sefiddasht during 2011–2015. Climatic parameters included temperature (mean daily, absolute maximum, absolute minimum, monthly maximum and monthly minimum), monthly humidity (absolute maximum, absolute minimum and average) and monthly precipitation. These factors were determined by Inverse Distance Weighted method using 19 meteorological stations in Semnan province due to an absence of climatological and synoptic stations on this site. Vegetation cover percent and production were measured within two 400m transects and 20 plots (1×1m2) along transects. Means comparisons were made between the years in terms of vegetation production and canopy cover using Duncan test, and the relationship between climatic factors with vegetation parameters which were determined using linear regression. Results show that production varies significantly over years (P<0.05). The lowest production rates in Margesar and Sefiddasht were observed in 2013-2014 with 254 and 213.3 kg/ha respectively. Although the precipitation significantly decreased from 293 mm in 2011-2012 to 173 mm in 2013-2014(P<0.05), but stepwise regression indicated that finally in Margesar, absolute maximum temperature and absolute minimum humidity in December and in Sefiddasht, absolute maximum temperature in June and absolute minimum temperature in August were entered in production forecasting model. This indicates that forage production is highly sensitive to absolute mentioned climatic parameters in addition to rainfall. Also, due to short period of growing season in these years, grazing period should also be limited; therefore, ranchers and the government should optimize rangeland management and reduce the length of the grazing period, decreasing grazing capacity or alternative livelihoods such as ecotourism, beekeeping and exploitation of medicinal plants. پرونده مقاله