Maseyk Kadmiel, Wingate Lisa, Seibt Ulli, Ghashghaie Jaleh, Bathellier Camille, Almeida Pedro, Lobo de Vale Raquel, Pereira Joao S, Yakir Dan, Mencuccini Maurizio
BIOEMCO (UMR 7618), Universite de Pierre et Marie Curie, Paris, France.
Isotopes Environ Health Stud. 2009 Dec;45(4):343-59. doi: 10.1080/10256010903388212.
The flux (R(s)) and carbon isotopic composition (delta(13)C (Rs)) of soil respired CO (2) was measured every 2 h over the course of three diel cycles in a Mediterranean oak woodland, together with measurements of the delta(13)C composition of leaf, root and soil organic matter (delta(13)C (SOM)) and metabolites. Simulations of R(s) and delta(13)C (Rs) were also made using a numerical model parameterised with the SOM data and assuming short-term production rates were driven mainly by temperature. Average values of delta(13)C (Rs) over the study period were within the range of root metabolite and average delta(13)C (SOM) values, but enriched in (13)C relative to the bulk delta(13)C of leaf, litter, and roots and the upper soil organic layers. There was good agreement between model output and observed CO (2) fluxes and the underlying features of delta(13)C (Rs). Observed diel variations of 0.5 per thousand in delta(13)C (Rs) were predicted by the model in response to temperature-related shifts in production rates along a approximately 3 per thousand gradient observed in the profile of delta(13)C (SOM). However, observed delta(13)C (Rs) varied by over 2 per thousand, indicating that both dynamics in soil respiratory metabolism and physical processes can influence short-term variability of delta(13)C (Rs).
在地中海橡树林中，每2小时测量一次土壤呼吸产生的二氧化碳通量（R(s)）和碳同位素组成（δ(13)C (Rs)），同时测量叶片、根系和土壤有机质（δ(13)C (SOM)）及代谢产物的δ(13)C组成。还使用一个根据SOM数据参数化的数值模型对R(s)和δ(13)C (Rs)进行了模拟，并假设短期生产率主要受温度驱动。研究期间δ(13)C (Rs)的平均值在根系代谢产物和δ(13)C (SOM)平均值范围内，但相对于叶片、凋落物、根系以及上层土壤有机质的整体δ(13)C，其(13)C含量有所富集。模型输出与观测到的二氧化碳通量以及δ(13)C (Rs)的基本特征之间具有良好的一致性。模型预测，δ(13)C (Rs)会因生产率与温度相关的变化而出现0.5‰的昼夜变化，这一变化沿着δ(13)C (SOM)剖面中观测到的约3‰梯度发生。然而，观测到的δ(13)C (Rs)变化超过2‰，这表明土壤呼吸代谢动态和物理过程都会影响δ(13)C (Rs)的短期变异性。
