Title: Soil organic and inorganic carbon difference along ecological zones in Mongolia

Soil carbon is the key part of terrestrial carbon storage and cycling. It consists of soil organic carbon (SOC) and soil inorganic carbon (SIC). There is limited information available on Mongolia's regional soil carbon stock. The study's aims were to quantify current regional soil carbon stocks and to investigate the interaction between SOC and relevant environmental variables such as latitude gradient, elevation, precipitation, and temperature. Soil samples were collected at 0-5 and 5-30 cm soil depth at 134 sampling sites within the six ecological zones in Mongolia. The mean soil organic carbon contents were 9.53 kg/m² in the meadow steppe zone, 9.6 kg/m² in steppe zones, 5.58 kg/m² in the dry steppe zone, 4.67 kg/m² in the arid steppe zone, 2.02 kg/m² in the desert steppe zone, and 1.57 kg/m² in the steppe desert zone. Soil inorganic carbon stocks ranged from 0.2 to 4.6 kg/m² within the ecological zones. Soil organic carbon was 25-98% of the carbon along the northern ecological zones. Soil inorganic carbon dominated the soil in southern zones, especially in the desert steppe and steppe desert zones (70-75% of the soil carbon). Soil organic carbon and soil inorganic carbon in Mongolian soils for the depth of 0-30 cm were estimated to be 4.8 Pg and 1.8 Pg, respectively. Elevation, latitude gradient, precipitation, and temperature parameters have a significant effect on soil carbon content and stocks. This study provides a general overview of current stocks of soil carbon, as well as the effect of climatic parameters and landscape on soil carbon content, along the ecological zones in southern Mongolia.