The effect of hydrological conditions mimicking hydropeaking on seed germination and species diversity in riparian seed banks

Sammanfattning

Hydropower regulation and hydropeaking alter hydrological conditions in riparian zones, potentially affecting seed germination and plant diversity. This study investigated how simulated hydropeaking conditions influenced germination and species diversity in soil seed banks collected from 16 riparian sites downstream of hydropower dams in the northern part of Sweden. Soil samples were exposed to three hydrological treatments: moist, daily waterlogging, and continuous waterlogging during a ten-week germination experiment. Seedling emergence and species diversity were analysed using generalized linear mixed models (GLMM). In total, 717 seedlings germinated across all treatments, with similar numbers observed in moist, daily waterlogged, and continuously waterlogged conditions. No significant effects of treatment were found on either seedling emergence or the Shannon diversity index. These results suggest that many riparian plant species are adapted to fluctuating hydrological conditions and are capable of germinating under both moist and waterlogged environments. Overall, the study indicates that short-term hydrological variation caused by hydropeaking had limited effects on seed bank germination and species diversity, highlighting the resilience of riparian vegetation in hydrologically altered river systems.