Global warming induces new constraints on forest ecosystems and requires forest management adaptation. The reduction of stand density is currently debated in France as a potential tool to face increasing summer drought risk by improving forest resistance to climate change-induced tree mortality. However, few studies have yet assessed the potential impact of this management change on soil biodiversity. We conducted a large-scale assessment of soil macro-detritivore assemblage response to stand density experimental manipulation. A total of 33 stands were studied covering a wide gradient of stand density, i.e. stand basal area from 2.5 to 43.7 m2.ha-1, stand age, i.e. 18 to 171-year-old, and pedoclimatic context conditions. We observed contrasted responses according to both taxonomic and functional group considered. Exploratory analysis highlight that those changes were mainly related to understorey vegetation, microclimatic and soil pH condition alterations. Soil macro-detritivore assemblages response to stand density manipulation was consistent over the stand age gradient. Among the litter-dwelling macro-detritivores, millipede abundance and diversity decreased with stand density reduction while woodlice and epigeic earthworms were unaffected. Further, a shift in the composition of soil-dwelling earthworm assemblage was observed. Endogeic earthworm abundance and diversity showed a strong increase with stand density reduction whereas anecic earthworm abundance tends to decrease. The estimated species richness of anecic earthworms followed a significant humpbacked relationship with highest values at intermediate stand density. Our study provides evidences that reducing stand density will have substantial impacts on soil macro-detritivore assemblages, especially in mull stands. Functional consequences of those alterations are discussed in light of functional redundancy and insurance hypothesis theories. Managing stand density of oak forest at intermediate level, i.e. 25 m2.ha-1, appears as the best way to optimize the trade-off between improving forest resistance to climate change and ensuring the conservation of functional diversity to preserve forest ecosystem functioning and stability.