Format: ORAL

Jos ngel Morales Snchez1, Kristiina Mark1, lo Niinemets1,2

1 Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, Tartu, Estonia 2 Estonian Academy of Sciences, Tallinn, Estonia

The concentration of atmospheric CO2 has been constantly increasing since the industrial revolution and it is projected to rise even further, surpassing 1000 ppm at the end of this century in the worst-case scenario. In vascular plants, influences of rising CO2 have been studied extensively, but there are much fewer studies for bryophytes. This is a significant omission as these organisms are major contributors to biodiversity in high latitudes and play key roles in ecosystem functioning. We conducted a long-term in vitro CO2 elevation experiment with four bryophyte species to assess the effect of elevated CO2 (1000 ppm) on bryophyte desiccation tolerance and desiccation-rehydration cycles. Real-time kinetics of gas-exchange and chlorophyll fluorescence were monitored throughout a year, with measurements taken every four months. The results show a reduction of photosynthetic activity under elevated CO2 in the four species studied. Long-term exposure to elevated CO2 negatively affected the photosynthetic recovery and carbon balance after desiccation-rehydration, however interspecific differences were observed in the responses to elevated CO2. These results highlight the importance of studying species-specific responses to climatic disturbances that might affect their photosynthetic characteristics in distinct ways. This study provides insight into the variable responses of bryophytes to environmental change that can potentially affect their fitness and role in the ecosystems under the current global change.