Li Nan, Zhou Guiyao, Krishna Mayank, Zhai Kaiyan, Shao Junjiong, Liu Ruiqiang, Zhou Xuhui
Northeast Asia Ecosystem Carbon Sink Research Center (NACC), Key Laboratory of Sustainable Forest Ecosystem Management, Ministry of Education, School of Ecology, Northeast Forestry University, Harbin 150040, China.
Laboratorio de Biodiversidad y Funcionamiento Ecosistémico, Instituto de Recursos Naturales y Agrobiología de Sevilla (IRNAS), Consejo Superior de Investigaciones Científicas (CSIC), 41012 Sevilla, Spain.
Plants (Basel). 2024 Nov 26;13(23):3321. doi: 10.3390/plants13233321.
Understanding the sensitivity of ecosystem respiration (ER) to increasing temperature is crucial to predict how the terrestrial carbon sink responds to a warming climate. The temperature sensitivity of ER may vary on a diurnal basis but is poorly understood due to the paucity of observational sites documenting real ER during daytime at a global scale. Here, we used an improved flux partitioning approach to estimate the apparent temperature sensitivity of ER during the daytime (E) and nighttime (E) derived from multiyear observations of 189 FLUXNET sites. Our results demonstrated that E is significantly higher than E across all biomes, with significant seasonal variations in the day-night discrepancy in the temperature sensitivity of ER (ΔE = E/E) except for evergreen broadleaf forest and savannas. Such seasonal variations in ΔE mainly result from the effect of temperature and the seasonal amplitude of NDVI. We predict that future warming will decrease ΔE due to the reduced E by the end of the century in most regions. Moreover, we further find that disregarding the ΔE leads to an overestimation of annual ER by 10~80% globally. Thus, our study highlights that the divergent temperature dependencies between day- and nighttime ER should be incorporated into Earth system models to improve predictions of carbon-climate change feedback under future warming scenarios.
了解生态系统呼吸（ER）对温度升高的敏感性对于预测陆地碳汇如何应对气候变暖至关重要。ER的温度敏感性可能在昼夜基础上有所不同，但由于全球范围内缺乏记录白天实际ER的观测站点，人们对此了解甚少。在这里，我们使用一种改进的通量划分方法，根据189个FLUXNET站点的多年观测数据，估算白天（E）和夜间（E）ER的表观温度敏感性。我们的结果表明，在所有生物群落中，E显著高于E，除常绿阔叶林和热带稀树草原外，ER温度敏感性的昼夜差异（ΔE = E/E）存在显著的季节变化。ΔE的这种季节变化主要是由温度效应和归一化植被指数（NDVI）的季节幅度引起的。我们预测，由于本世纪末大多数地区E降低，未来变暖将导致ΔE减小。此外，我们进一步发现，忽略ΔE会导致全球年ER高估10%至80%。因此，我们的研究强调，应将白天和夜间ER之间不同的温度依赖性纳入地球系统模型，以改善对未来变暖情景下碳-气候变化反馈的预测。
