Negative soil respiration fluxes in unneglectable arid regions

This study examines the hypothesis that soil respiration fluxes are always positive, neglecting negative fluxes in arid regions that characterize more than 30% of Earth’s total land area. To cut down uncertainty, we focus on non-vegetated areas at a typical, large arid region (Central Asia). Soil respiration fluxes were reconciled as a direct sum of influxes (CO₂ fluxes entering soils) and effluxes (CO₂ fluxes released from soils). It was indicated that the annual average of effluxes was only 8% higher than that of influxes in 1979-2011. At typically alkaline sites (soil pH>9.5), extreme local annual average of soil respiration fluxes are negative. Therefore, negative soil respiration fluxes in arid regions are unneglectable. Although the soil respiration flux is useful as a measure of CO₂ effluxes from the soils and CO₂ influxes to the soils, its value as a measure of ecosystem processes is very much limited.