Tree species and management controls on the water storage in forest soil and underlying slope deposits revealed by electrical resistivity tomography

Abstract Water is a critical factor in forest production and its sustainable development. In addition, it contributes to the stability of forest ecosystems, essential for the growth and development of individual trees and stands. Electrical resistivity tomography (ERT) is the ideal method for detecting soil moisture among currently available methods. The advantages over other methods are mainly in the non-destructiveness of the measurement, i.e. it does not disturb the soil body. In this work, we deal with the influence of forest management on the dynamics of soil moisture and soil water storage. The measurements were carried out in the core zone of the Dobroč primaeval forest (plots Dobroč 1, Dobroč 2, Dobroč 3), in the buffer zone of the Dobroč primaeval forest with a predominance of European beech (Beech forest) and in the spruce monoculture near the buffer zone (Spruce forest). Measurements were made using ERT using the time-lapse method, while the detected soil resistance was calibrated to soil moisture. To calibrate the spatial variability of moisture, we used the time domain reflectometry (TDR) method to determine the volumetric soil water content. By calibrating between TDR and ERT using calibration equations, we determined the quantity of retained soil water within the measured profile. The results showed that the lowest soil water storage was on the spruce stand plot (53.31 ±9.55 dm 3 m–3). On the contrary, the highest soil water storage was found on the Dobroč 2 plot (133.14 ±5.37 dm 3 m–3). The decrease in soil water storage was the highest in the managed spruce forest. According to the amount of retained soil water, it appears to be the most resistant forest ecosystem of the Dobroč primaeval forest. The trend of soil water storage was more balanced in these ecosystems during the growing season than in areas outside the primaeval forest. Average soil water storage also reached higher values in these plots. The knowledge gained from the study can inform decisions about forest management in Slovakia and contribute to both the mitigation of climate change effects and the adaptation of forests, ensuring that the hydrological functions of forest ecosystems are maintained.