What impacts the soil moisture dynamics in the near-natural beech forest?

Soil moisture in forested regions displays considerable spatial and temporal variability within the soil-plant interaction. The high frequency of drying and wetting cycles exacerbates the uncertainty in this already complex relationship. Recent studies in forest hydrology have frequently postulated that soil physical properties and precipitation partitioning induce soil water content (SWC) variability. However, in-situ evidence for this linkage is scarce. To support the notion of SWC patterns corresponding to these two elements, a transect-based method was utilised. It clarifies the variation in soil moisture on a small scale and facilitates the identification of specific patterns with the distance from the tree stem. An intensive monitoring of SWC (52 profiles) and precipitation, including throughfall and stemflow, has been carried out in the near-natural beech forest in north-eastern Germany since 2022. It covers three study sites that are stocked over a terminal moraine and are classified as wet, intermediate and dry on the basis of the soil moisture gradient. The result stipulates increase of the SWC away from the stem during drying cycles at the dry study site. However, this appears to be the reverse for the wet site. During the wetting phase, soil moisture at intermediate and dry sites exhibited homogeneous variation, although the wet site experienced an increase in soil moisture by stem distance. Therefore, uncovering the distance from stem, root density distribution and canopy structure as possible controlling factors. It is concluded, that within soil-plant interaction both soil physics and precipitation define the patterns of soil moisture variation during wetting cycles. Conversely, soil retention characteristics mainly anticipate water fluxes in the soil during drying periods.