Automated measurements of greenhouse gases fluxes from tree stems and soils: magnitudes, patterns and drivers
Automated measurements of greenhouse gases fluxes from tree stems and soils: magnitudes, patterns and drivers
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DOI：
10.1038/s41598-019-39663-8
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发表时间：
2019-03-08
影响因子：
4.6
通讯作者：
Vargas, Rodrigo
中科院分区：
文献类型：
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作者：
Barba, Josep;Poyatos, Rafael;Vargas, Rodrigo
树干与大气交换二氧化碳、甲烷和氧化亚氮，但这些温室气体 (GHG) 通量的大小、模式和驱动因素仍然知之甚少。我们的理解主要来自静态手动测量，它提供了有关这些通量的时间变化和大小的有限信息。我们测量了温带高地森林内两个茎高度和邻近土壤的每小时 CO2、CH4 和 N2O 通量。我们分析了通量和生物物理驱动因素（即温度、土壤湿度、树液通量）的日间和季节变化。树干是CO2（3.80 +/- 0.18 mu mol m(-2) s(-1)；平均值+/- 95% CI）和CH4（0.37 +/- 0.18 nmol m(-2) s(-1)）的净来源，但也是N2O的汇（-0.016 +/- 0.008 nmol m(-2) s(-1)）。时间序列分析显示这些气体与特定日期的温度或液流通量之间的日时间相关性。 CO2 和 CH4 显示出明显的季节性模式，可以用温度、土壤含水量和树液通量来解释。茎、土壤通量及其驱动因素之间的关系表明，茎排放的 CH4 可能部分在地下产生。高频测量表明： a) 树干在多个时间尺度与大气交换温室气体； b) 需要更好地估计通量大小并了解温室气体排放的基本机制。
Tree stems exchange CO2, CH4 and N2O with the atmosphere but the magnitudes, patterns and drivers of these greenhouse gas (GHG) fluxes remain poorly understood. Our understanding mainly comes from static-manual measurements, which provide limited information on the temporal variability and magnitude of these fluxes. We measured hourly CO2, CH4 and N2O fluxes at two stem heights and adjacent soils within an upland temperate forest. We analyzed diurnal and seasonal variability of fluxes and biophysical drivers (i.e., temperature, soil moisture, sap flux). Tree stems were a net source of CO2 (3.80 +/- 0.18 mu mol m(-2) s(-1); mean +/- 95% CI) and CH4 (0.37 +/- 0.18 nmol m(-2) s(-1)), but a sink for N2O (-0.016 +/- 0.008 nmol m(-2) s(-1)). Time series analysis showed diurnal temporal correlations between these gases with temperature or sap flux for certain days. CO2 and CH4 showed a clear seasonal pattern explained by temperature, soil water content and sap flux. Relationships between stem, soil fluxes and their drivers suggest that CH4 for stem emissions could be partially produced belowground. High-frequency measurements demonstrate that: a) tree stems exchange GHGs with the atmosphere at multiple time scales; and b) are needed to better estimate fluxes magnitudes and understand underlying mechanisms of GHG stem emissions.