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5 years ago Boone et al. 1998: Roots exert a strong influence on the temperature sensitivity of soil respiration https://www.nature.com/articles/25119 Here we show that, for a mixed temperate forest, respiration by roots plus oxidation of rhizosphere carbon, which together produce a large portion of total effluxed soil CO2, is more temperature-sensitive than the respiration of bulk soil. We determine that the Q10 value (the coefficient for the exponential relationship between soil respiration and temperature, multiplied by ten) is 4.6 for autotrophic root respiration plus rhizosphere decomposition, 2.5 for respiration by soil lacking roots and 3.5 for respiration by bulk soil.
Greater phenological seasonality of AR than that of HR (Boone et al., 1998, Widen and Majdi, 2001, Tierney et al., 2003) could partly account for its higher Q10. For instance, apparent temperature sensitivities would be inflated if data from springtime root growing periods were included (Hanson et al., 2003). Furthermore, changes in substrate supply from photosynthesis could also largely be overlooked, resulting in additional overestimation of the temperature sensitivity of AR (Bhupinderpal-Singh et al., 2003, Davidson and Janssens, 2006).
Wang et al. 2014: Soil respiration under climate warming: differential response of heterotrophic and autotrophic respiration https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.12620 Here, we use meta‐analysis to synthesize 202 soil respiration datasets from 50 ecosystem warming experiments across multiple terrestrial ecosystems. We found that, on average, warming by 2 °C increased soil respiration by 12% during the early warming years, but warming‐induced drought partially offset this effect. More significantly, the two components of soil respiration, heterotrophic respiration and autotrophic respiration showed distinct responses. The warming effect on autotrophic respiration was not statistically detectable during the early warming years, but nonetheless decreased with treatment duration. In contrast, warming by 2 °C increased heterotrophic respiration by an average of 21%, and this stimulation remained stable over the warming duration. This result challenged the assumption that microbial activity would acclimate to the rising temperature. Together, our findings demonstrate that distinguishing heterotrophic respiration and autotrophic respiration would allow us better understand and predict the long‐term response of soil respiration to warming.