Land-use conversion profoundly influences the soil pore structure, consequently modifying the soil functions. Investigating the variation of multiscale soil pore structure and their associated functions following land-use change is critical for evaluating land management strategies. However, this topic has not yet been extensively explored in recent studies. In this study, the pore structure of soil following land-use conversion was quantitatively investigated by multiscale X-ray tomography. Intact soil aggregates and undisturbed soil cores were collected from paddy fields (PF) and from vegetable fields were converted from paddy fields for 5 years (VF-5), 13 years (VF-13), and 20 years (VF-20), respectively. Results revealed that the connected porosity of both aggregates and soil cores was significantly increased after land-use conversion. The isolated porosity of soil aggregates increased, while, conversely, it decreased for soil cores. The variance in pore structure was attributed to the development of new pores, including channels created by vegetable roots, fissures, earthworm holes, and packing pores resulting from the decomposition of soil organic matter and the rearrangement of soil particles. The altered pore structure influenced the soil exchangeability and reservation ability. For aggregates, the isolated porosity of PF and VF-5 accounted for over 70% of the total imaged porosity. These aggregates displayed a larger water and carbon reservation ability, but limited exchangeability of air, water, and nutrients. The isolated porosity of VF-13 and VF-20 aggregates accounted for approximately 50% of the total imaged porosity, suggesting they could effectively balance the exchange and storage of air, water, and nutrients. As for soil cores, isolated pores became negligible (<0.2%) following land-use conversion, leading to the emergence of a drainable pore system suitable for vegetable plantation. These findings offer insights into the development of pore structures and the prediction of soil function variations at multiple scales, both of which are crucial for optimizing soil management protocols.

中文翻译：

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多尺度 X 射线断层扫描识别土地利用转换后土壤孔隙结构变化及相关功能预测


土地利用转换对土壤孔隙结构产生深远影响，从而改变土壤功能。研究土地利用变化后多尺度土壤孔隙结构的变化及其相关功能对于评估土地管理策略至关重要。然而，在最近的研究中，这个话题还没有得到广泛探讨。本研究通过多尺度 X 射线断层扫描定量研究了土地利用转换后土壤的孔隙结构。从稻田 （PF） 和菜地中收集完整土壤团聚体和未受干扰的土壤核心，分别从稻田转化 5 年 （VF-5） 、 13 年 （VF-13） 和 20 年 （VF-20）。结果表明，土地利用转换后，团聚体和土芯的连通孔隙度均显著增加。土壤团聚体的孤立孔隙率增加，而相反，土壤核心的孤立孔隙率降低。孔隙结构的差异归因于新孔隙的发育，包括由植物根、裂缝、蚯蚓孔以及土壤有机质分解和土壤颗粒重排产生的填充孔隙。孔隙结构的改变影响了土壤的交换性和保留能力。对于聚集体，PF 和 VF-5 的孤立孔隙率占总成像孔隙率的 70% 以上。这些聚集体显示出较大的水和碳保留能力，但空气、水和营养物质的交换能力有限。VF-13 和 VF-20 聚集体的孤立孔隙率约占总成像孔隙率的 50%，表明它们可以有效地平衡空气、水和营养物质的交换和储存。 至于土壤核心，在土地利用转换后，孤立的孔隙变得可以忽略不计（<0.2%），导致出现了适合蔬菜种植的可排水孔隙系统。这些发现为孔隙结构的发展和多尺度土壤功能变化的预测提供了见解，这两者都对于优化土壤管理方案至关重要。