Ecosystem respiration is a key flux in the terrestrial carbon cycle and is affected substantially by temperature. This work analysed the time series data of nighttime net ecosystem exchange of carbon dioxide (NEEnight) from 196 FLUXNET2015 sites to re‐evaluate the relationships between NEEnight and temperature. A total of 93 sites (48%) were identified to have a unimodal relationship between NEEnight and temperature. Site‐specific apparent optimum temperature parameters were then estimated at these sites. We further assessed the impacts of using exponential or unimodal equations on NEEnight predictions. The predicted NEEnight values at high temperatures were substantially higher from the exponential‐type equations (mean: ~200%) than from the unimodal equation (mean: ~30%), compared to the observed NEEnight. This study calls for using a unimodal equation to predict NEEnight (often considered as nighttime ecosystem respiration, ERnight), which could substantially improve the accuracy and reduce uncertainty in ER estimates, in particular under the scenario of global warming.

中文翻译：

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涡流相关通量塔位点夜间生态系统呼吸与温度的指数或单峰关系


生态系统呼吸是陆地碳循环中的关键通量，受温度的影响很大。这项工作分析了来自 196 个FLUXNET2015站点的夜间净生态系统二氧化碳交换 （NEEnight） 的时间序列数据，以重新评估 NEEnight 与温度之间的关系。共有 93 个站点 （48%） 被确定为 NEEnight 与温度之间存在单峰关系。然后在这些地点估计特定地点的表观最佳温度参数。我们进一步评估了使用指数或单峰方程对 NEEnight 预测的影响。与观察到的 NEEnight 相比，指数型方程（平均值：~200%）在高温下预测的 NEEnight 值远高于单峰方程（平均值：~30%）。本研究呼吁使用单峰方程来预测 NEEnight（通常被认为是夜间生态系统呼吸，ERnight），这可以大大提高 ER 估计的准确性并减少 ER 估计的不确定性，尤其是在全球变暖的情况下。