Subsidient: Laura McManus/Utrecht University
Subsidie: S171.68
Northern Sweden has experienced boreal stream channelisation whereby stream complexity is reduced to accommodate log floating practices. Channelisation caused changes in the role of flooding resulting in an altered species composition. Restoration has proven unsuccessful in encouraging the return of desired species. Seedbanks could be important for riparian diversity. Furthermore, boreal flooding regimes are undergoing changes due to global warming. Accordingly, the main research question of this project aims to uncover how flooding affects the role of hydrochory in the formation of seedbanks in boreal river systems. This was accomplished by releasing seeds into restored boreal streams and ascertaining their stranding locations. At locations where high and low quantities of released seeds were recorded, the seedbank content was subsequently determined, this was also determined for non-flooded plots. At flooded locations where many seeds stranded a larger seedbank was found in comparison to flooded locations where few seeds stranded. Non-flooded plots also had smaller seedbanks than flooded plots. Surface water velocity was negatively correlated with seed stranding and channel slope, boulder density and geomorphological complexity was negatively correlated with seedbank content. Therefore, flooding was determined to play a significant role in the formation of seedbanks in restored boreal streams.
