Investigation of Carbon Sequestration Potential of Ungrazed Rangelands in Winter Rangelands of Sorkhkola, Sari

Rangelands are containing more than one-third of earth's biosphere carbon stocks that can able to absorb atmosphere carbon dioxide by their vegetation and accumulate in plant tissues and soil. Animal grazing as a human factor could be effect on the amount of absorption. In this study, the effect of grazing on carbon sequestration is studied in grazed and ungrazed winter rangelands of Sorkhkola in Sari. After determining the type of vegetation and dominant species (Hordeum glaucum), sampling was done by randomly-systematic method and 20 plots (1m2). The plant biomass of shoot and root was determined by direct measurement. Then, samples were weighed and dry matter was calculated for each organs. The soil sampling was done from each horizon (0-15 and 15-30 cm) based on boundary separation of the surface and underlying horizon in the area. Organic carbon percentage of plant and soil samples was obtained in laboratory. As well as other soil properties including bulk density, soil texture, calcium carbonate, electrical conductivity and soil reaction was determined. Finally, the grazed and ungrazed area data was analyzed using independent t-test in SPSS 16 software. The results showed that a significant reduction of carbon sequestration from aerial to underground organs area in grazed and protected sites (p≤0/01). Despite the decline in soil carbon sequestration through grazing to protected area had no significant differences between the first and second soil depth. Also, the result showed that sequestration rate was much higher in the soil to plant. It was 97% and 99% of the carbon sequestration in the protected and grazed area respectively.