Coupled soil-plant water dynamics - Environmental drivers and species effects

预测的气候和土地利用变化可能对土壤-植被系统的水分平衡产生巨大影响，特别是在干旱条件下。然而，关于根系土壤层土壤水分的时空动态、植物水分获取的动态和植物叶片蒸腾作用的信息很少，这些信息将使预测变化的影响具有特征。计划中的项目的中心目标是定量地描述植物水分利用（受不同植物功能群的生根模式和生理影响）与生态系统的水文水平衡之间的相互作用。重点将放在干旱和复湿对这种相互作用的影响上。我们将重点研究植物的形态和生理参数，以及植物对土壤水分供应和林分特性变化的功能适应，这些变化驱动着植物的吸水能力和实际吸水量。植物和植被对优先流道、土壤储水、水力再分配和水渗透能力的影响是本项目的第二个重点。到目前为止，土壤水分运动和植物水分吸收的短期时空动态从未在高时间分辨率下连续表征过。然而，这种高分辨率的方法是理解遭受干旱-再湿润过渡的生态系统中的水平衡的先决条件。因此，该项目的一个方法学重点是进一步发展和应用新的创新技术，使土壤、水和蒸腾的同位素特征得以持续追踪。

The predicted climate and land-use changes could have dramatic effects on the water balance of the soil-vegetation system in particular under drought conditions. However, information is scarce on temporal and spatial dynamics of soil water in the rooted soil horizons, the dynamics of plant water acquisition and on transpiration from plant leaves that will allow characterizing the effects of the predicted changes. The central aim of the planned project is to quantitatively characterise the interaction between plant water use – as affected by rooting patterns and physiology of different plant functional groups – and the hydrological water balance of an ecosystem. A main emphasis will be put on the effects of droughts and rewetting on this interaction. We will focus on the morphological and physiological parameters and on functional adaptations of plants to changes in soil water supply and stand specific proprieties, which drive water uptake capacity and actual water uptake. The effect of plants and vegetation on preferential flow paths, soil water storage, hydraulic redistribution and water infiltration capacity is in the second focus of this project. Until present short-term spatial and temporal dynamics of soil water movement and plant water uptake have never been characterised continuously in high temporal resolution. Such high-resolution approaches are, however, a prerequisite for understanding the water balance in ecosystems subjected to drought-rewetting transitions. As a consequence a methodological focus of this project is the further development and application of new innovative techniques that allow the continuous tracing of isotope signatures in soil water and transpiration.