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Soil Respiration Responses to Experimental Warming

Paper Reviewed
Carey, J.C., Tang, J., Templer, P.H., Kroeger, K.D., Crowther, T.W., Burton, A.J., Dukes, J.S., Emmett, B., Frey, S.D., Heskel, M.A., Jiang, L., Machmuller, M.B., Mohan, J., Panetta, A.M., Reich, P.B., Reinsch, S., Wang, X., Allison, S.D., Bamminger, C., Bridgham, S., Collins, S.L., de Dato, G., Eddy, W, C., Enqist, B.J., Estiarte, M., Harte, J., Henderson, A., Johnson, B.R., Larson, K.S., Luo, Y., Marhan, S., Melillo, J.M., Penuelas, J., Pfeifer-Meister, L., Poll, C., Rastetter, E., Reinmann, A.B., Reynolds, L.L., Schmidt, I.K., Shaver, G.R., Strong, A.L., Suseela, V. and Tietema, A. 2016. Temperature response of soil respiration largely unaltered with experimental warming. Proceedings of the National Academy of Sciences USA 113: 13,797-13,802.

Introducing their intriguing paper, Carey et al. (2016) state that for some time now, climatic warming has been "hypothesized to increase rates of soil respiration [which releases CO2 to the atmosphere], potentially fueling further increases in global temperatures." But is this hypothesis correct?

Determined to answer their own question, the 43 scientists -- hailing from nine different countries (Australia, China, Denmark, Germany, Italy, Spain, the Netherlands, the United States and the United Kingdom) -- developed what they describe as "the largest global dataset to date of soil respiration, moisture and temperature measurements, totaling more than 3,800 observations representing 27 temperature manipulation studies, spanning nine biomes and over two decades of warming." And what did this mammoth undertaking reveal?

Carey et al. report that based on data from all warming durations and seasons, they observed (1) "no significant differences in the temperature sensitivity of soil respiration between warmed or control treatments within each individual biome, with the exception of boreal forest and desert." And they further note that they observed (2) "increases in soil respiration rates with increasing temperatures in most non-desert biomes up to ~25°C," above which temperature (3) "soil respiration rates either leveled off or slightly decreased," which is a truly important finding, in light of the fact, as they note, that (4) "compared with anthropogenic emissions, roughly nine times more carbon dioxide is released from soils to the atmosphere via soil respiration on an annual basis," which decrease in CO2 emissions further suggests that (5) Earth's mean global temperature might actually decrease somewhat with the passage of time and the documented decrease in soil respiration rates.

Posted 18 April 2017