Bioaccumulative Response of Quercus robur L. to a Soil Sodification Gradient in a Central European Floodplain Forest

Under ongoing climate change and increasing land-use intensity, understanding the response of different tree species to soil sodification and salinization is essential for sustainable forest management. In this study, we evaluated the content of Na, Cl−, Fe, Mn, and SO42− in the leaves of 90 mature pedunculate oak (Quercus robur L.) trees growing in floodplain forests along a soil sodification gradient associated with shallow, highly mineralized groundwater. Foliar contents of Na+, Cl−, and SO42− showed no trend along the sodification gradient, whereas Mn and, to a lesser extent, Fe contents decreased with increasing sodification. All substances were only weakly related to soil predictors. Furthermore, coupling between soil and leaf contents was weak, indicating groundwater as the dominant influence. Despite decades of sodification, element contents remained substantially lower than values reported in experimental salinity studies on Quercus spp. and generally fell at the lower end of the range reported for salinization-affected sites. These findings suggest that mature Q. robur effectively regulate the physiological uptake and transport of salts into leaves, highlighting the species’ tolerance to long-term environmental sodification. The results support the suitability of Q. robur for environments affected by increasing soil salinization.