Soil CO2 Flux in Hövsgöl National Park, Northern Mongolia

We investigated soil CO2 fl ux and bare soil respiration in grasslands that are located at the southern edge of the Siberian boreal forest in Northern Mongolia. The study area has warmed by almost 1.8oC over the last 40 years, and the soil and vegetation covers have been changed due to intense nomadic grazing pressure. Bare soil respiration is decreased with increasing grazing pressure, but there was no consistent pattern of total soil CO2 fl ux under three distinct grazing levels. Bare soil respiration and soil CO2 fl ux were higher on north-facing slopes than on south-facing slopes, due to high organic matter accumulation and the presence of permafrost. Both bare soil respiration and soil CO2 fl ux were signifi cantly higher in riparian areas compared with the lower and upper portions of the south-facing slope. Topography has a stronger effect on variability of soil CO2 fl ux and bare soil respiration than variability induced by grazing. Inter-annual variability in soil CO2 fl ux and bare soil respiration was very high, because of high variability in climate conditions.