THE EFFECT OF STOCKING RATE ON CARBON SEQUESTRATION OF PRANGOS FERULACEA (CASE STUDY: GORGOU SUMMER RANGELANDS, KOHGILUYEH AND BOYER-AHMAD PROVINCE, IRAN)

Rangelands are the most important ecosystem for carbon sequestration. Knowledge of plant response to grazing is one of important requirements for rangeland management. Stocking rate is one of main factors in destruction of the vegetation cover in rangeland ecosystems. Livestock grazing has the potential to substantially alter carbon storage in grassland ecosystem. This study examined the effects of grazing management on carbon sequestrations of Prangos ferulacea as dominant species in summer rangeland of Gorgou summer rangelands in Kohgiluyeh and Boyer-Ahmad Province, Iran. Four sites with high, moderate, low and enclosure grazing intensity with stocking rates of 3.4, 2.9, 1.4 and 0 (Animal Unit/Ha), respectively were chosen for the study. Samples were collected from 50 plots of 1.5×1m2 in May 2014. In each site, the carbon content of aboveground and root biomass and litter were measured by ash method and soil carbon by Walcky-Black method. Results showed that stocking rate had a significant effect on carbon sequestration of P. ferulacea for above and underground biomass, litter and soil carbon. For all of traits, the lowest carbon sequestration was obtained in high grazing intensity that had a significant difference with other sites. Enclosure and high grazing with average values of 42 and 6 (kg/ha) had the highest and lowest carbon sequestration amounts by P. ferulacea, respectively. Stocking rate of 2.9 (au/ha) was introduced as the suitable grazing intensity to protect the ability of carbon sequestration by P. ferulacea.