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Root Respiration and Global Warming
Burton, A.J., Melillo, J.M. and Frey, S.D. 2008. Adjustment of forest ecosystem root respiration as temperature warms. Journal of Integrative Plant Biology 50: 1467-1483.

The authors write that "increases in terrestrial ecosystem respiration as temperatures warm could create a positive feedback that causes atmospheric CO2 concentration, and subsequently global temperature, to increase more rapidly," as climate alarmists often contend, but that "if plant tissue respiration acclimates to temperature over time, this feedback loop will be weakened, reducing the potential temperature increase."

What was done
In an attempt to determine which of these scenarios is closer to the truth, Burton et al. employed published values of annual root respiration rates to assess "the cross-ecosystem rate of increase with temperature," after which they examined "the potential for trade-offs between root metabolic capacity and biomass in regulating ecosystem root respiration, using published values for mid-growing season root specific respiration rates and root biomass," finally determining "if relationships that occur across ecosystems adapted to different climates might also exist within an ecosystem that is subjected to warming," which they did by analyzing data obtained "from soil warming studies, including recent measurements of fine root respiration made at three warming experiments at Harvard Forest."

What was learned
The three researchers say their several analyses of the pertinent scientific literature indicated there was "a clear trend for decreasing root metabolic capacity (respiration rate at a standard temperature) with increasing mean annual temperature," there were "no instances of high growing season respiration rates and high root biomass occurring together," and that in the soil warming experiments at Harvard Forest, there were "decreases in metabolic capacity for roots from the heated plots".

What it means
In the words of Burton et al., "these findings clearly suggest that modeling efforts that allow root respiration to increase exponentially with temperature, with Q10 values of 2 or more, may over-predict root contributions to ecosystem CO2 efflux for future climates and underestimate the amount of carbon available for other uses, including net primary productivity," pretty much rebuffing long-espoused climate-alarmist claims to the contrary.

Reviewed 24 December 2008