Biological Soil Crusts Sequestering Carbon in Dryland Soils
Lane, R.W., Menon, M., McQuaid, J.B., Adams, D.G., Thomas, A.D., Hoon, S.R. and Dougill, A.J. 2013. Laboratory analysis of the effects of elevated atmospheric carbon dioxide on respiration in biological soil crusts. Journal of Arid Environments 98: 52-59.
Working with dynamic gas exchange chambers and cyanobacteria-dominated BSCs taken from the Kalahari Sand soils of southern Africa, Lane et al. set out to quantify short-term changes in carbon exchange (respiration and photosynthesis) of these BSCs when the air's CO2 concentration was doubled to approximately 800 ppm under two different wetting treatments of 2 and 5 mm of applied water, characteristic of "light and heavy rainfall events," respectively. In doing so, the seven UK scientists report the BSCs that received 5 mm of wetting increased their rate of carbon sequestration by approximately three-fold, and those subject to 2 mm of wetting increased their rate of carbon sequestration by a full order of magnitude!
In the final paragraph of their paper, Lane et al. state "BSCs have the potential to fix carbon under limited soil moisture availability and nutrient poor soils (typical of drylands)," especially in the case of BSCs dominated by nitrogen fixing cyanobacteria. And, therefore, they conclude "undisturbed BSC-covered drylands could be enhanced carbon sinks, and play an increasingly significant role in global carbon budgets in years to come."
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