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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Partitioning net ecosystem exchange of CO2: A comparison of a Bayesian/isotope approach to environmental regression methods
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Partitioning net ecosystem exchange of CO2: A comparison of a Bayesian/isotope approach to environmental regression methods

机译：划分CO2的净生态系统交换：贝叶斯/同位素方法与环境回归方法的比较

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Separation of the net ecosystem exchange of CO2 (F) into its component fluxes of net photosynthesis (F A ) and nonfoliar respiration (F R ) is important in understanding the physical and environmental controls on these fluxes, and how these fluxes may respond to environmental change. In this paper, we evaluate a partitioning method based on a combination of stable isotopes of CO2 and Bayesian optimization in the context of partitioning methods based on regressions with environmental variables. We combined high-resolution measurements of stable carbon isotopes of CO2, ecosystem fluxes, and meteorological variables with a Bayesian parameter optimization approach to estimate F A and F R in a subalpine forest in Colorado, United States, over the course of 104 days during summer 2003. Results were generally in agreement with the independent environmental regression methods of Reichstein et al. (2005a) and Yi et al. (2004). Half-hourly posterior parameter estimates of F A and F R derived from the Bayesian/isotopic method showed a strong diurnal pattern in both, consistent with established gross photosynthesis (GEE) and total ecosystem respiration (TER) relationships. Isotope-derived F A was functionally dependent on light, but F R exhibited the expected temperature dependence only when the prior estimates for F R were temperature-based. Examination of the posterior correlation matrix revealed that the available data were insufficient to independently resolve all the Bayesian-estimated parameters in our model. This could be due to a small isotopic disequilibrium () between F A and F R , poor characterization of whole-canopy photosynthetic discrimination or the isotopic flux (isoflux, analogous to net ecosystem exchange of 13CO2). The positive sign of indicates that F A was more enriched in 13C than F R . Possible reasons for this are discussed in the context of recent literature.
机译：将生态系统的净二氧化碳交换（F）分离为其净光合作用（F A）和非叶片呼吸（F R）的通量，对于理解这些通量的物理和环境控制以及这些通量如何响应环境变化非常重要。在本文中，我们在基于环境变量回归的分区方法的背景下，评估了基于CO2稳定同位素与贝叶斯优化相结合的分区方法。我们将高分辨率的CO2稳定碳同位素测量，生态系统通量和气象变量与贝叶斯参数优化方法相结合，以估计美国科罗拉多州亚高山森林在2003年夏季的FA和FR的过程，历时104天。结果通常与Reichstein等人的独立环境回归方法一致。 （2005a）和Yi等。 （2004）。从贝叶斯/同位素方法得出的F A和F R半小时后验参数估计值均显示出强烈的昼夜模式，这与既定的总光合作用（GEE）和总生态系统呼吸（TER）关系一致。同位素衍生的F A在功能上依赖于光，但是F R仅在先前对F R的估计基于温度的情况下才显示出预期的温度依赖性。后验相关矩阵的检验表明，可用数据不足以独立解析我们模型中的所有贝叶斯估计参数。这可能是由于F A和F R之间的同位素不平衡（）小，对整个冠层的光合分辨能力或同位素通量（isoflux，类似于13CO2的净生态系统交换）表征不佳。正号表示F A在13C中比F R富集更多。在最近的文献中讨论了可能的原因。

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