CO2 exchange of three separate linden shoots was measured with an automatic chamber system operating continuously at the site from June to September in 2020-2021. The chambers were mostly open enabling natural radiation and precipitation conditions. They closed automatically two times per hour for 2 minutes at a time resulting in 48 exchange rates per chamber in one day in naturally varying environmental conditions. The CO2 exchange was calculated from the rate of change in the CO2 concentration during the closure. A simple light response curve was fitted into these exchange rates. Daily photosynthesis was then calculated by summing the instantaneous rates. Data has been used in Thölix et al., 2024.