Thomas et al. 2011. Soil respiration at five sites along the Kalahari Transect: Effects of temperature, precipitation pulses and biological soil crust cover.

Thomas, A.D., Hoon, S.R., Dougill, A.J., 2011. Soil respiration at five sites along the Kalahari Transect: Effects of temperature, precipitation pulses and biological soil crust cover. Geoderma 167-168, . 284-294.

Abstract

There are increasing concerns that climatic and land use changes will enhance soil respiration rates and soil organic carbon loss, compromising agricultural productivity and further elevating atmospheric CO₂. Current understanding of dryland respiration is, however, insufficient to enable prediction of the consequences of these changes for dryland soils and CO₂ fluxes. The objectives of this paper are to present in-situ respiration data from five remote sites along a climatic gradient in the Kalahari of Botswana and to determine the effects of temperature, moisture and biological crust cover on soil CO₂ fluxes. Moisture was the primary limiting factor to efflux which increased with amount of simulated rainfall. On dry soils, mean CO₂ efflux was between 1.5 and 5.9 mg C m^− 2 h^− 1. After 2 mm and 50 mm simulated wetting, mean rates increased to 4.0 to 21.8 and 8.6 to 41.5 mg C m^− 2 h^− 1 respectively. Once wet, soil CO₂ efflux increases with temperature, and sites at the hotter northern end of the transect lost more CO₂ than cooler southerly sites. Net respiration rates are, however, muted by autotrophic organisms in biological soil crusts which photosynthesise and take up CO₂. The temperature sensitivity of soil CO₂ efflux increased with moisture. Dry, 2 mm and 50 mm treated soils had a Q₁₀ of 1.1, 1.5 and 1.95 respectively. Our findings indicate that higher temperatures and a loss of biological crust cover will lead to greater soil C loss through respiration.