The selective extractions suggest that a significant part of U and Th is primarily held by Fe-bearing silicates. Our results suggest that the tree substitution seems to produce a large dissolution of these minerals under the Oaks, resulting to a release of U and Th. However, below 25 cm no impact of this release was observed on U-series disequilibria. A scenario allowing to reconcile the significant mobilization of U and the constancy of U-series disequilibria is proposed. Above 25 cm, additional pedogenic redistribution of U and Th isotopes occurs in all the profiles, inducing some discrepancies between U-series disequilibria. A clear correlation between the (230Th/234U) ratios and the proportions of amorphous and interlayer Al hydroxides has been highlighted. This correlation suggests a mobility of U and Th isotopes strongly associated to Al dynamics in these soils rather than Fe, despite the primary location of U in the Fe-bearing silicates and the overwhelming reported control of UVI by Fe-oxides in oxidized environments. These pedogenic processes make the shallowest horizons of podzolic soils unsuitable for U-series dating. In contrast, a soil production rate can be deduced from the deepest soil layers which do not show such effects on the U-series nuclides. The reproducible U-series disequilibria measured in four whole-profile replicates emphasize the robustness and the significance of the “long-lived” U-series disequilibria in deep soil layers relative to long-term weathering rates, independent of transient perturbations such as land cover changes. Finally, because Ra can strongly accumulates in plants, the (226Ra/230Th) ratios in the different soils were affected by the flux of 226Ra released by litter degradation. The use of this ratio as a long-term chronometer should therefore be performed with caution in such contexts. No direct impact of the vegetation type on the (228Ra/232Th) ratios was identified, due to the short 228Ra half-life.