Initial oak regeneration responses to experimental warming along microclimatic and macroclimatic gradients

Quercusspp. are one of the most important tree genera in temperate deciduous forestsin terms of biodiversity, economic and cultural perspectives. However, natural regener-ation of oaks, depending on specific environmental conditions, is still not sufficientlyunderstood. Oak regeneration dynamics are impacted by climate change, but these cli-mate impacts will depend on local forest management and light and temperatureconditions.•Here, we studied germination, survival and seedling performance (i.e. abovegroundbiomass, height, root collar diameter and specific leaf area) of four oak species (Q. cer-ris, Q. ilex, Q.roburandQ. petraea). Acorns were sown across a wide latitudinal gradi-ent, from Italy to Sweden, and across several microclimatic gradients located withinand beyond the species’ natural ranges. Microclimatic gradients were applied in termsof forest structure, distance to the forest edge and experimental warming.•We found strong interactions between species and latitude, as well as between micro-climate and latitude or species. The species thus reacted differently to local andregional changes in light and temperature ; in southern regions the temperateQ.roburandQ. petraeaperformed best in plots with a complex structure, whereas the Mediter-raneanQ. ilexandQ. cerrisperformed better in simply structured forests with areduced microclimatic buffering capacity. The experimental warming treatment onlyenhanced height and aboveground biomass of Mediterranean species.•Our results show that local microclimatic gradients play a key role in the initial stagesof oak regeneration; however, one needs to consider the species-specific responses toforest structure and the macroclimatic context.