Negative soil respiration fluxes in unneglectable arid regions

Abstract

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.