How do thermal migration distance and extreme cold events affect seedling emergence and survival in assisted migration schemes in the sub-Mediterranean context? What role does plant provenance play? Can biotic interactions such as nurse effect of the overstorey and shrub layer buffer the negative responses to plant translocation? Are any of these effects species-specific? Three pinewoods in the Catalan Pre-Pyrenees, northeast Iberian Peninsula. We used a replicated field trial to test the early years establishment of two contrasted provenances of four Quercus species (Q. coccifera, Q. ilex, Q. faginea and Q. pubescens) that were sown and planted along gradients of elevation and understorey microsite conditions in sub-Mediterranean pinewoods. Seedling responses to translocation were evaluated through seedling emergence, seedling survival and re-sprouting after dieback events according to seedling provenance, thermal migration distance, extreme cold events and microenvironment. The study reports high success of both the planting (with an overall 76.3% of initial 3-yr survival) and sowing (with an overall 50% of seedling emergence) experiments. The results show that: (1) the thermal migration distance and the occurrence of extreme cold events have strong effects on the responses of the translocated species (particularly the evergreen oaks); (2) the forest overstorey plays an important role in attenuating the negative effects of thermal migration distance on seedling survival; and (3) these responses are species-specific. The evergreen Quercus species showed more evidence of high ecotypic differentiation in terms of cold tolerance, enabling local provenances to respond better to translocation. In contrast, marcescent species, showed high phenotypic plasticity that led to a better overall establishment success. The implementation of assisted migration is a feasible option to increase the diversity and resilience of the sub-Mediterranean pinewoods. Assisted migration programmes should manage risks by thoroughly considering thermal migration distances and the occurrence of extreme cold events when selecting species and seed sources, since Mediterranean tree species show different strategies regarding adaptation to cold. Programme managers should also consider the advantage of planting/sowing under relatively closed canopy to buffer some of the negative responses associated with translocation.