Evaluation of Five Gas Diffusion Models Used in the Gradient Method for Estimating CO2 Flux with Changing Soil Properties
Evaluation of Five Gas Diffusion Models Used in the Gradient Method for Estimating CO2 Flux with Changing Soil Properties
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DOI：
10.3390/su131910874
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发表时间：
2021-09
期刊：
影响因子：
3.9
通讯作者：
Xiaofei Yan;Qinxin Guo;Yajie Zhao;Yandong Zhao;Jianhui Lin
中科院分区：
文献类型：
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作者：
Xiaofei Yan;Qinxin Guo;Yajie Zhao;Yandong Zhao;Jianhui Lin
梯度法估算土壤CO2通量的独特之处在于它能提供土壤剖面CO2产生和消耗的额外信息。然而，选择一个合适的气体扩散模型与梯度方法的信心是一个很大的挑战。不存在普遍适用的最佳扩散模型，而只有在特定土壤中最适合的模型。本文对五种常用的扩散模型分别在实验室土壤性质变化条件下和在林场的适用性进行了评价。在实验室条件下，改变土壤水分、容重和肥力状况，探讨了5种扩散模型的适用性。此外，本文还利用梯度法估算了4种不同气候条件下林场土壤CO2通量的日变化，并对5种模型的适用性进行了分析。室内和林间试验结果均表明，Moldrup模型的估测精度最高，其次是Millington-Quirk模型，Penman、马歇尔和Penman-Millington-Quirk模型的估测精度较差。结果表明，梯度法估算的土壤CO2通量对扩散模型高度敏感，对土壤性质的变化不敏感。一般来说，梯度法可以作为一个实用的，成本效益高的工具来研究土壤呼吸，只有当适当的扩散模型是第一次确定。
The gradient method used to estimate soil CO2 flux is distinctive because it can provide additional information about CO2 production and consumption of soil profile. However, choosing an appropriate gas diffusion model with confidence with the gradient method is a big challenge. There is no universal optimal diffusion model but only the most suitable model in specific soils. This paper evaluates the applicability of five commonly used diffusion models in laboratory with changing soil properties and in a forest farm, respectively. When soil moisture, bulk density and fertility status were changed in the laboratory, the applicability of the five diffusion models was discussed. Moreover, this paper shows diurnal variation of soil CO2 flux estimated by the gradient method under four different climatic conditions in the forest farm, and the applicability of the five models was also analyzed. Both laboratory and forest experimental results confirm that the estimating accuracy of the Moldrup model is the highest, followed by the Millington–Quirk model, while those of the Penman, Marshall and Penman–Millington–Quirk models are poor. Furthermore, the results indicate that soil CO2 flux estimated by the gradient method is highly sensitive to the diffusion model and insensitive to the changes of soil properties. In general, the gradient method can be used as a practical, cost-effective tool to study soil respiration only when the appropriate diffusion model is first determined.