Gene-environment interactions govern early regeneration in fir and beech: evidence from participatory provenance trials across Europe

O_LIForest regeneration is shaped by strong demographic filters during germination and early establishment, yet the relative contributions of provenance and environment remain poorly resolved under natural conditions. C_LIO_LIWe combined climate-chamber trials with a continental-scale, field-based citizen science seed-sowing experiment to quantify germination, early phenological development, and three-year post-germination survival fir (Abies spp.) and beech (Fagus spp.) provenances across Europe. Using mixed-effects models and a state-based Markov framework to reconstruct phenological trajectories, we quantified successive demographic filters from seed to established seedling. C_LIO_LIGermination was structured by genotype-by-environment interactions (G x E) in both genera, but with contrasting expression: fir showed broadly parallel environmental responses among provenances and partial concordance between climate-chamber and field, whereas beech showed strong provenance-by-environment responses and weak predictability from controlled conditions. Seed weight was a key axis in beech (lighter seeds germinated more and developed faster), but confounded with geographic differentiation in fir. C_LIO_LIIn contrast to germination, post-establishment survival was dominated by site-level environmental filtering with limited consistent provenance effects, revealing a life-stage shift from fine-scale G x E during germination and early development to broader environmental control of survival--an important consideration for regeneration--based management and assisted migration. C_LI