Dynamic flows as a ecological restoration method : How will the riparian vegegation change by implementing seasonal flow variation in the regulated Jukt River?

Regulation and alteration of streams and rivers have a long history and dams provide us with resources. It also degrades the ecosystems connected to them by cutting off transportation routes and changing the flow regime. Riparian ecosystems have evolved to the natural flow regimes, making them sensitive to hydrological alterations. Riparian plant communities are often species rich and have a positive impact on their surroundings, but are often degraded because of flow alteration. Studies predict that riparian zones will lose species and extent because of climate change, making it increasingly important to manage and restore them. This report examines the potential effects of two scenarios of a planned re-introduction of natural flow variation in the regulated river Juktån in Sweden. Riparian vegetation composition and cover was inventoried in plots with different amount of yearly flooding to assess current relationships between flooding and riparian vegetation. A rating curve was used to determine the relationship between discharge and river stage. GIS-modeling using LiDAR data and the rating curve made it possible to predict the extent of flooding with the two scenarios, and resulting potential changes in vegetation extent and composition. No significant correlation was found between species richness and number of days flooded under current flooding regime. Positive correlation was however found between elevation and species richness, bare soil and flooding, and vascular plant cover and flooding. The three most species-rich vegetation belts are expected to increase substantially in area with both scenarios, suggesting that positive response is likely with the introduction seasonal flow variation