Connectivity is one of the most important parameters to quantify pore structure and link it to soil functions. One of the great challenges in quantifying connectivity with X‐ray microtomography (X‐ray μCT) is that high resolution, as required for small pores, can only be achieved in small samples in which the connectivity of larger pores can no longer be quantified in a meaningful way. The objective of this study was to investigate the changes in pore connectivity with changing sample size, covering a range of analysed pore diameters of more than three orders of magnitude. With this approach, we wanted to address whether pore types formed by different processes in an agricultural chronosequence leave characteristic traces in certain connectivity metrics. The Euler number, χ, and the connection probability of two random points within the pore system, that is, the Γ‐indicator, were determined as a function of minimum pore diameter. The results show that characteristic signatures of certain pore types overlap with scale artifacts in the connectivity functions. The Γ‐indicator, gives highly biased information in small samples. Therefore, we developed a new method for a joint‐Γ‐curve that merges information from three samples sizes. However, χ does not require such a scale fusion. It can be used to define characteristic size ranges for pore types and is very sensitive to the occurrence of bottle necks. Our findings suggest a joint evaluation of both connectivity metrics to disentangle different pore types with χ and to identify the contribution of different pore types to the overall pore connectivity with Γ. This evaluation on the chronosequence showed that biopores mainly connect pores of diameters between 0.5 and 0.1 mm. This was not coupled with an increase in pore volume. In contrast, tillage led to a shift of pores of diameter >0.05 mm towards pores of diameter >0.20 mm and thus increased connectivity of pores >0.20 mm. This work underlines the importance of accounting for the scale dependence of connectivity measures and provides a methodological approach for doing so.

中文翻译：

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使用X射线CT揭示各种尺度和分辨率的毛孔连通性

连通性是量化孔隙结构并将其与土壤功能联系起来的最重要参数之一。用X射线显微断层照相术（X-rayμCT）量化连通性的重大挑战之一是，只有在小样品中才能实现小孔所要求的高分辨率，而在这些小样品中，大孔的连通性不再能够定量。一种有意义的方式。这项研究的目的是研究孔隙连通性随样品大小变化的变化，涵盖了超过三个数量级的分析孔径范围。通过这种方法，我们想解决由农业时间序列中的不同过程形成的孔类型是否在某些连通性指标中留下特征痕迹的问题。欧拉数χ 并确定孔隙系统中两个随机点（即Γ指示剂）的连接概率与最小孔径的函数关系。结果表明，某些孔隙类型的特征性特征与连通性函数中的尺度伪影重叠。Γ指标可在小样本中提供高度偏差的信息。因此，我们为联合Γ曲线开发了一种新方法，该方法可以合并来自三个样本大小的信息。但是，χ不需要这样的规模融合。它可用于定义孔类型的特征尺寸范围，并且对瓶颈的发生非常敏感。我们的发现建议对两种连通性指标进行联合评估，以区分不同的孔隙类型与χ，并确定不同孔隙类型对Γ总体孔隙连通性的贡献。对时间序列的评估表明，生物孔主要连接直径在0.5到0.1 mm之间的孔。这并没有增加孔体积。相反，耕作导致直径> 0.05 mm的孔向直径> 0.20 mm的孔移动，从而增加了> 0.20 mm的孔的连通性。这项工作强调了考虑连通性措施的规模依赖性的重要性，并为此提供了一种方法论方法。