Impacts of Rangeland Reclamation and Management on Carbon Stock in North East of Iran (Case Study: Kardeh Basin, Mashhad, Iran

Abstract. 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.