比利时鲁汶大学Javaux, M.和瑞士苏黎世联邦理工学院Carminati, A.团队合作的一项最新研究，探明了土壤质地对生态系统水限制的全球影响。相关论文发表在2024年10月23日出版的《自然》杂志上。 

据介绍，低土壤湿度和高蒸汽压亏缺（VPD）会加剧植物的水分胁迫，并引发包括蒸腾和光合作用减少等各种干旱反应。当土壤干燥度低于临界土壤湿度阈值时，生态系统从能量向水分限制过渡，气孔关闭以减轻水分胁迫。然而，在生态系统尺度上，这些阈值背后的机制仍然定义不明确。

研究团队分析了对全球土壤临界水分阈值的观测结果，土壤水力导率曲线显示了土壤质地在调节生态系统水分限制开始中的突出作用，土壤导率曲线的陡峭度随着沙粒含量的增加而增加。

这阐明了生态系统对VPD和土壤水分的敏感性是如何由土壤质地决定的，沙质土壤的生态系统对土壤干燥相对更敏感，而粘性土壤的生态系统对VPD相对更敏感。由于同样的原因，沙质土壤中的植物适应水分限制的潜力有限，这对气候变化如何影响陆地生态系统产生了响应。综上所述，尽管植被—大气交换受大气条件驱动，并由植物调节介导，但其命运最终取决于土壤。

附：英文原文

Title: Global influence of soil texture on ecosystem water limitation

Author: Wankmller, F. J. P., Delval, L., Lehmann, P., Baur, M. J., Cecere, A., Wolf, S., Or, D., Javaux, M., Carminati, A.

Issue&Volume: 2024-10-23

Abstract: Low soil moisture and high vapour pressure deficit (VPD) cause plant water stress and lead to a variety of drought responses, including a reduction in transpiration and photosynthesis. When soils dry below critical soil moisture thresholds, ecosystems transition from energy to water limitation as stomata close to alleviate water stress. However, the mechanisms behind these thresholds remain poorly defined at the ecosystem scale. Here, by analysing observations of critical soil moisture thresholds globally, we show the prominent role of soil texture in modulating the onset of ecosystem water limitation through the soil hydraulic conductivity curve, whose steepness increases with sand fraction. This clarifies how ecosystem sensitivity to VPD versus soil moisture is shaped by soil texture, with ecosystems in sandy soils being relatively more sensitive to soil drying, whereas ecosystems in clayey soils are relatively more sensitive to VPD. For the same reason, plants in sandy soils have limited potential to adjust to water limitations, which has an impact on how climate change affects terrestrial ecosystems. In summary, although vegetation–atmosphere exchanges are driven by atmospheric conditions and mediated by plant adjustments, their fate is ultimately dependent on the soil.

DOI: 10.1038/s41586-024-08089-2

Source: https://www.nature.com/articles/s41586-024-08089-2