Laboratory incubation studies evaluating the temperature sensitivity of soil respiration often use measurements of respiration taken at a constant incubation temperature from soil that has been pre-incubated at the same constant temperature. However, such constant temperature incubations do not represent the field situation where soils undergo diurnal temperature oscillations. We investigated the legacy effects of constant and diurnally oscillating temperatures on soil respiration and soil microbial community composition. A grassland soil from the United Kingdom was either incubated at a constant temperature of 5°C, 10°C, or 15°C, or diurnally oscillated between 5°C and 15°C. Soil CO₂ flux was measured by temporarily moving incubated soils from each of the above-mentioned treatments to 5°C, 10°C or 15°C, such that soils incubated under every temperature regime had CO₂ flux measured at each temperature. We hypothesised that, irrespective of measurement temperature, CO₂ emitted from the 5°C to 15°C oscillating incubation would be most like the soil incubated at 10°C. The results showed that both incubation and measurement temperatures separately influence soil respiration. Oscillations between 5°C and 15°C resulted in significantly greater CO₂ flux than constant incubations at 10°C or 5°C but were not significantly different from the 15°C incubation. The greater CO₂ flux from soils previously incubated at 15°C, or oscillating between 5°C and 15°C, coincided with a depletion of dissolved organic carbon and a shift in the phospholipid fatty acid profile of the soil microbial community, consistent with stress associated with substrate depletion and microbial starvation when incubated at higher temperatures. Our results suggest that daily maximum temperatures are more important than daily minimum or daily average temperatures when considering the response of soil respiration to the diurnally asymmetric warming that is expected to occur as a result of climate change.

中文翻译：

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恒定和昼夜振荡温度对土壤呼吸和微生物群落结构的遗留影响

评估土壤呼吸的温度敏感性的实验室孵化研究通常使用在恒定孵化温度下从已在相同恒定温度下预孵化的土壤中进行的呼吸测量。然而，这种恒温培养并不代表土壤经历昼夜温度振荡的田间情况。我们研究了恒定和昼夜振荡温度对土壤呼吸和土壤微生物群落组成的遗留影响。来自英国的草地土壤要么在 5°C、10°C 或 15°C 的恒定温度下培养，要么在 5°C 和 15°C 之间昼夜振荡。土壤CO ₂通量是通过将上述每种处理的培养土壤暂时移动到 5°C、10°C 或 15°C 来测量的，这样在每个温度范围下培养的土壤都在每个温度下测量 CO ₂通量。我们假设，无论测量温度如何，从 5°C 到 15°C 振荡孵育排放的 CO ₂最类似于在 10°C 下孵育的土壤。结果表明，培养温度和测量温度分别影响土壤呼吸。5°C 和 15°C 之间的振荡导致 CO ₂通量明显高于 10°C 或 5°C 的恒定孵育，但与 15°C 孵育没有显着差异。更大的CO ₂先前在 15°C 下孵育或在 5°C 和 15°C 之间振荡的土壤通量与溶解有机碳的耗尽和土壤微生物群落磷脂脂肪酸谱的变化同时发生，与底物相关的压力一致在较高温度下孵育时会耗尽和微生物饥饿。我们的结果表明，在考虑土壤呼吸对预计因气候变化而发生的昼夜不对称变暖的响应时，日最高温度比日最低温度或日平均温度更重要。