Bimodal and unimodal radial growth of Mediterranean oaks along a coast-inland gradient

•Autumn growth period significantly enhances annual ring width in the Mediterranean.•Radial growth follows intra-annual variability of water availability.•Bimodality is high on the Mediterranean coast but not at Atlantic and inland sites.•Growth bimodality is higher for diffuse-porous compared with ring-porous oaks.•Between-species differences in radial growth dynamics might facilitate coexistence.