Climate warming can affect the temperature sensitivity of microbial activity and growth efficiency, possibly explained by changes to microbially unavailable carbon (C) protected within in soil aggregates. We assessed physical protection by crushing macroaggregates (250–2000 μm) and microaggregates (<250 μm) isolated from mineral soils exposed to 27 years of experimental warming (+5 °C). We hypothesized that removal of physical protection would increase microbial activity and reduce C use efficiency (CUE). We found that crushing increased microbial respiration and biomass turnover rate, but did not affect CUE. We also hypothesized that long-term warming would reduce the effect of physical protection on microbial activity, and that physical protection would attenuate microbial temperature sensitivity in heated compared to control soils. We found that long-term warming was associated with a smaller effect of physical protection for microbial respiration but with a larger effect for biomass turnover rate in macroaggregates. Physical protection reduced the temperature sensitivity of respiration but enhanced the temperature sensitivity of microbial biomass turnover rate in heated compared to control soils. Our work shows that long-term warming has contrasting effects on how microbial respiration, biomass turnover rate, and their thermal responses are mediated by physical protection within soil aggregates.

气候变暖会影响微生物活动和生长效率的温度敏感性，这可能由土壤团聚体中受保护的微生物无法利用的碳（C）的变化所解释。我们通过粉碎从暴露于暴露了27年的实验变暖（+5°C）的矿物土壤中的大骨料（250-2000μm）和微骨料（<250μm）来评估物理保护。我们假设取消物理防护将增加微生物活性并降低C使用效率（CUE）。我们发现压碎增加了微生物的呼吸作用和生物量的周转率，但没有影响CUE。我们还假设长期变暖会降低物理防护对微生物活性的影响，并且与对照土壤相比，物理防护会减弱加热后的微生物对温度的敏感性。我们发现，长期变暖与大型骨料中物理防护作用对微生物呼吸作用较小，而对生物质转化率作用较大。与对照土壤相比，物理保护降低了呼吸的温度敏感性，但提高了加热条件下微生物生物质周转率的温度敏感性。我们的工作表明，长期升温对土壤团聚体中的物理保护如何介导微生物呼吸，生物量周转率及其热响应产生了相反的影响。与对照土壤相比，物理保护降低了呼吸的温度敏感性，但提高了加热条件下微生物生物质周转率的温度敏感性。我们的工作表明，长期升温对土壤团聚体中的物理保护如何介导微生物呼吸，生物量周转率及其热响应产生了相反的影响。与对照土壤相比，物理保护降低了呼吸的温度敏感性，但提高了加热条件下微生物生物质周转率的温度敏感性。我们的工作表明，长期升温对土壤团聚体中的物理保护如何介导微生物呼吸，生物量周转率及其热响应产生了相反的影响。