Variation of Carbon Sequestration in Halocnemum strobilaceum and Soil under Livestock Grazing (Case Study: Salt Lands of Golestan Province, Iran)

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Background: Grazing intensity has a major effect on soil and biomass organic carbon storage (C). Various plants and ecosytems with deiffernt charactristices have their unique responses to the grazing. Recognizing the effects of grazing intensity on C in various envrionments dominated by Halocnemum strobilaceum, such as Incheboron salt land of Golestan province, helps plannig the grazing startegies. Materials and Methods: Three grazing sites, viz. heavy grazing (in vicinity of resting point), moderate grazing (at a distance of 650 meters from resting point) and light grazing (at a distance of 2050 meters from resting point) were selceted. Sampling of soil and H. strobilaceum species was carried out with systematic-random method in Nov. 2012. In this regard, fifteen plants along the five 100 meters transects (with distance of 30m) were randomly selected and underground and abovegrond organs were extracted. The amount of biomass C was determined by combustion method. Also, soil sampling with five repetation was carried out in two depths (0-20 cm and 20-40 cm) and the amount of stored C was determined by Walkly and Black method. Results: The sum of underground and aboveground biomass C in light grazing site was more than the heavy and moderate grazing sites, which were about 1.17, 1.07 and 0.567 ton/hectare respectively. The amount of soil C for the mentioned sites were 162.56, 137,39 and 80.76 ton/hectare, respectively. Besides, the depth 0-20 cm in all sites had a higher C. The soil C comprised more than 99 percent of ecosystem total stored C (biomas and soil C) in each site. In terms of total ecosystem C, the heavy and moderate grazing site had about 84.37 and 32.20 ton/hectare less C compred to light grazing site. Conclusions: From a management perspective, it is concluded that light grazing intesity in saltalnd region can lead to maintenance of C in high level and grazing systems should avoid high stocking rates because it may adversely affect soil C. Heavy grazing has more negative effects on C compared to moderate grazing. Both soil and biomass respond similarly to different grazing intensities. The soil, especially first depth as the main resourcse of C, should be protected from detrioration to prevent C decling. In view point of C sequestration, it is suggested to plan grazing intesity in light level and protect the soil of rangelands.the five 100 meters transects (with distance of 30m) were selected and underground and abovegrond organs were extracted. The amount of biomass C was determined by combustion method. Also, soil sampling with five repetation was carried out on two depths (0-20 cm and 20-40 cm) and the amount of stored C was determined by Walkly and Black method. The results showed that the sum of underground and aboveground biomass C in light grazing site is more than the heavy and moderate grazing sites. This value is about 1.17, 1.07 and 0.567 ton/hectare for light, moderate and heavy grazing, respectively. The amount of soil C for the and soil C) in each of sites.