Collar Properties and Measurement Time Confer Minimal Bias Overall on Annual Soil Respiration Estimates in a Global Database
Collar Properties and Measurement Time Confer Minimal Bias Overall on Annual Soil Respiration Estimates in a Global Database
复制标题
DOI：
10.1029/2020jg006066
复制
发表时间：
2020-11
期刊：
影响因子：
--
通讯作者：
J. Jian;C. Gough;D. Sihi;A. Hopple;B. Bond‐Lamberty
中科院分区：
文献类型：
--
作者：
J. Jian;C. Gough;D. Sihi;A. Hopple;B. Bond‐Lamberty
测量土壤-大气二氧化碳（CO2）通量（土壤呼吸，RS）对于了解陆地碳平衡和预测气候变化非常重要。这种测量通常使用永久插入土壤表面的测量环来进行。然而，测量持续时间和频率的差异，以及衣领的属性，可能会导致偏差的估计年度RS。使用最新更新的全球RS数据库（SRDB-V5），我们研究了与5个方法学因素相关的年度RS偏倚：颈领高度、颈领覆盖面积、颈领插入深度、测量持续时间和测量频率。我们发现，每年RS与衣领插入深度呈负相关，一致的想法，衣领插入削减根，从而减少RS。年度RS也与颈领高度和颈领覆盖面积呈负相关，可能是因为在较大体积的腔室中难以实现均匀的顶空混合;然而，这些影响在数量上很小（平均RS的偏倚约为2%至10%）。我们发现测量持续时间或测量频率与年度RS没有相关性。这些结果表明，RS方法的变化通常会引入最小的偏倚。因此，最小调整的年度遥感测量的汇编提供了一个可靠的资源，综合研究，全球年度遥感建模，以及土壤碳如何响应气候变化的调查。
Measuring the soil‐to‐atmosphere carbon dioxide (CO2) flux (soil respiration, RS) is important to understanding terrestrial carbon balance and to forecasting climate change. Such measurements are frequently made using measurement collars permanently inserted into the soil surface. However, differences in measurement duration and frequency, as well as collar properties, may lead to biases in the estimation of annual RS. Using a newly updated global RS database (SRDB‐V5), we investigated the annual RS bias associated with five methodological factors: collar height, collar coverage area, collar insertion depth, measurement duration, and measurement frequency. We found that annual RS was negatively correlated with collar insertion depth, consistent with the idea that collar insertion cuts roots and thus reduces RS. Annual RS was also negatively related with collar height and collar coverage area, perhaps because uniform head‐space mixing is difficult to achieve in larger volume chambers; however, these effects were quantitatively small (bias of ~2% to 10% of mean RS). We found no correlation of measurement duration or measurement frequency with annual RS. These findings suggest that variation in RS methodology generally introduces minimal bias overall. Therefore, compilations of minimally adjusted annual RS measurements provide a reliable resource for synthesis studies, global annual RS modeling, and investigation of how soil carbon responds to climate change.