Multi-provenance assisted seed dispersal slows range contractions of sessile oak (Quercus petraea) in France

Rapid climate warming threatens the persistence of temperate European forests, challenging the long-standing assumption that local seed sources remain best adapted under future conditions. Yet operational frameworks for translating this challenge into actionable seed sourcing decisions remain scarce. 2. Using Quercus petraea in France as a model system, we combined provenance-specific species distribution models with a dynamic range-shift model (simRShift) to evaluate climate-informed assisted dispersal under SSP5-8.5 from 2020 to 2100, testing six regional provenances and five planting effort levels within the operational French seed zone framework used by national forest agencies. 3. Climatically suitable habitat declined sharply across all scenarios. Assisted dispersal substantially slowed this contraction: mixed-provenance plantings retained approximately 2.5 times more habitat than local-only strategies by 2100. 4. Provenance performance varied strongly across the landscape. Local provenances maintained advantages in topographically sheltered mountain regions, where current seed transfer regulations require no revision. In warmer lowlands, local-only strategies were increasingly outperformed from 2060 onward by Atlantic, continental, and Pyrenean origins. Seed transfers followed climatic gradients of aridity, continentality, and elevation, producing multi-directional and altitudinally stratified provenance mosaics rather than simple poleward shifts, with optimal donor identity varying systematically by elevation band within each seed zone. 5. Planting effort exhibited strong diminishing returns. Moderate interventions, approximately 5% of suitable sites per decade captured most achievable persistence gains while remaining within realistic nursery production and budgetary constraints, providing a practical operational target for national reforestation planning. 6. Synthesis and applications. Climate-explicit seed sourcing can substantially enhance the long-term persistence of temperate forest trees under rapid climate change. Mountain zones can maintain existing local-sourcing regulations, while lowland and transitional zones should begin incorporating climate-matched donor provenances within the next two to three decades. Embedding mixed-provenance strategies within existing seed zone frameworks, rather than replacing them, offers a scalable and immediately operational pathway for climate-adapted reforestation, balancing local adaptation with the introduction of pre-adapted genotypes to maintain forest resilience across heterogeneous landscapes.