Institute of Botany of the Czech Academy of Sciences, Zámek 1, Průhonice, CZ-252 43, Czech Republic.
New Phytol. 2024 Dec;244(5):1801-1811. doi: 10.1111/nph.20068. Epub 2024 Aug 22.
Soil moisture shapes ecological patterns and processes, but it is difficult to continuously measure soil moisture variability across the landscape. To overcome these limitations, soil moisture is often bioindicated using community-weighted means of the Ellenberg indicator values of vascular plant species. However, the ecology and distribution of plant species reflect soil water supply as well as atmospheric water demand. Therefore, we hypothesized that Ellenberg moisture values can also reflect atmospheric water demand expressed as a vapour pressure deficit (VPD). To test this hypothesis, we disentangled the relationships among soil water content, atmospheric vapour pressure deficit, and Ellenberg moisture values in the understory plant communities of temperate broadleaved forests in central Europe. Ellenberg moisture values reflected atmospheric VPD rather than soil water content consistently across local, landscape, and regional spatial scales, regardless of vegetation plot size, depth as well as method of soil moisture measurement. Using in situ microclimate measurements, we discovered that forest plant indicator values for moisture reflect an atmospheric VPD rather than soil water content. Many ecological patterns and processes correlated with Ellenberg moisture values and previously attributed to soil water supply are thus more likely driven by atmospheric water demand.
土壤湿度塑造了生态格局和过程，但很难在整个景观中连续测量土壤湿度的变化。为了克服这些限制，通常使用维管植物物种的 Ellenberg 指示值的群落加权平均值来生物指示土壤湿度。然而，植物物种的生态和分布既反映了土壤水分供应，也反映了大气水分需求。因此，我们假设 Ellenberg 湿度值也可以反映大气水分需求，表现为蒸气压亏缺（VPD）。为了验证这一假设，我们在中欧温带阔叶林的林下植物群落中，解析了土壤水分含量、大气蒸气压亏缺和 Ellenberg 湿度值之间的关系。无论植被样地大小、深度以及土壤水分测量方法如何，Ellenberg 湿度值在当地、景观和区域空间尺度上始终反映大气 VPD，而不是土壤水分含量。通过现场微气候测量，我们发现森林植物湿度指示值反映了大气 VPD，而不是土壤水分含量。因此，许多与 Ellenberg 湿度值相关的生态格局和过程，以前归因于土壤水分供应，更有可能是由大气水分需求驱动的。
