CO₂ efflux from the litter layer, litter heterotrophic respiration, is an important component of the forest carbon cycle. Litter heterotrophic respiration mediated by microorganisms varies in response to seasonal environmental changes, such as temperature and moisture. Here, we aimed to quantify seasonal variation in litter heterotrophic respiration and determine how the microbial biomass influences microbial activity and hence litter heterotrophic respiration in a warm temperate forest. We performed in situ high‐frequency measurements of litter heterotrophic respiration per unit area (R_{_area}), which are able to capture CO₂ pulses during rainfall, for over 2 years. Microbial activity, which is the CO₂ efflux per unit weight (R_{_mass}) considering the change in the amount of substrate, was calculated based on R_{_area}. In parallel, we measured substrate‐induced respiration (SIR) each month, as an index of microbial biomass. We identified seasonal hysteresis in R_{_area}, which was higher in spring (January to July) than in fall (August to December), despite the temperature being similar in both periods. Of interest, R_{_mass} and SIR also showed similar seasonal hysteresis in relation to temperature. Additionally, potential microbial activity without the effect of temperature and moisture was positively related to SIR. This result indicates that seasonal hysteresis with temperature in microbial activity was driven by microbial biomass seasonality, and thus, it leads to seasonal hysteresis in litter heterotrophic respiration in relation to temperature. Our findings highlight the importance of not only the environmental factors and substrate depletion but also biotic factors for estimating heterotrophic respiration.

中文翻译：

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在温带森林中，微生物生物量导致凋落物异养呼吸的季节性滞后与温度的关系

枯枝落叶层的CO ₂外排，枯枝异养呼吸是森林碳循环的重要组成部分。微生物介导的异养呼吸作用随温度和湿度等季节性环境变化而变化。在这里，我们旨在量化凋落异养呼吸的季节变化，并确定微生物生物量如何影响微生物活性，从而确定温暖温带森林中凋落异养的呼吸。我们对每单位面积（R _{_area}）的凋落异养呼吸进行了现场高频测量，能够捕获降雨超过2年的CO ₂脉冲。微生物活性，即CO ₂基于R _{_area}计算考虑底物量变化的每单位重量的流出量（R _{_mass}）。同时，我们每月测量底物诱导的呼吸（SIR），作为微生物生物量的指标。我们确定了R _{_area的}季节性滞后现象，尽管两个时期的温度相似，但春季（1月至7月）高于秋季（8月至12月）。有趣的是，R _{_mass}SIR也显示出与温度有关的相似的季节性滞后。另外，不受温度和湿度影响的潜在微生物活性与SIR正相关。该结果表明，微生物活动中随温度变化的季节性迟滞是由微生物生物量的季节性驱动的，因此，它导致凋落物异养呼吸的季节性迟滞与温度有关。我们的发现突出了不仅环境因素和底物消耗，而且生物因素对于估计异养呼吸的重要性。