The Response of Heterotrophic Soil Respiration to Warming
Bradford, M.A., Watts, B.W. and Davies, C.A. 2010. Thermal adaptation of heterotrophic soil respiration in laboratory microcosms. Global Change Biology 16: 1576-1588.
Taking a laboratory microcosm approach, Bradford et al. (2010) tested the potential for the mass-specific respiration (Rmass) in six different soils to adapt to three experimentally-imposed thermal regimes (a constant 10, 20 or 30°C) by periodically assaying soil subsamples "using similar approaches to those used in plant, animal and microbial thermal adaptation studies."
"As would be expected," the three researchers write, "after 77 days of incubation Rmass rates across the range of assay temperatures were greatest for the 10°C experimentally incubated soils and lowest for the 30°C soils, with the 20°C incubated soils intermediate."
Bradford et al. state that "well-established evolutionary trade-offs in controls on metabolic rates suggest that Rmass rates should be lower for organisms adapted to higher temperature regimes and vice-versa," citing Hochachka and Somero (2002); and they say their work "demonstrates that, for soils sampled from hardwood forests in the north- and southeastern United States, substrate Rmass rates of the microbial biomass when measured under conditions of excess glucose substrate availability, follow the expectations of established biochemical trade-offs." Thus, as ever more studies of the phenomenon are conducted, the old notion of soil respiration rising in response to global warming, and remaining high, is seen to be ever farther from the truth.
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