20141229
Author: Unger, S. Maguas, C. Pereira, J. S. David, T. S. Werner, C.
Year : 2010
Title: The influence of precipitation pulses on soil respiration - Assessing the "Birch effect" by stable carbon isotopes
Journal : Soil Biology & Biochemistry
Comment : Current hypotheses indicate that the “Birch” pulse is caused by rapidly increased respiration and mineralization rates in response to changing moisture conditions but the underlying mechanisms are still unclear. They continuously monitored CO2-fluxes along with their isotopic compositions before, during and after the irrigation. 13C signatures of the first CO2-efflux burst, occurring immediately after rewetting, fit the hypothesis that the “Birch” pulse is caused by the rapid mineralization of either dead microbial biomass or osmoregulatory substances released by soil microorganisms in response to hypo-osmotic stress in order to avoid celllyses. The response of soil CO2-efflux to rewetting was smaller under mild (May) than under severe drought (August) and isotopic compositions indicated a larger contribution of anaplerotic carbon uptake with increasing soil desiccation.
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