Repeated summer drought changes the radial xylem sap flow profile in mature Norway spruce but not in European beech

•Radial xylem sap flow profiles are rarely studied, especially under abiotic stress.•A beech/spruce forest was exposed to repeated seasonal drought and recovery.•HFD and TD type sensors were applied to measure the xylem sap flow density profile.•Repeated drought reduced the xylem sap flow profile in spruce but not in beech.•Radial sap flow profiles are altered by drought-induced leaf area reductions.