Objective: restoring riparian plants to improve the ecological status of rivers

Plants improving the health of rivers

Rivers are elements that go together with the progress of all civilizations. From a symmetrical perspective, they bring a series of services -potable water, food, raw materials, leisure activities, etc.-which benefit all society. However, the ecological status of rivers is being threatened by the impact of excessive water extraction, pollution and the alteration of riverbeds (dams, channels, etc.). 

In the natural environment, riparian formations are authentic natural corridors preserving biodiversity and landscape richness of the water environment. According to Cayetano Gutiérrez, member of the research group Freshwayer Ecology, Hydrology and Management (FEHM) of the UB, “recovering the riparian vegetation brings benefits: for instance, a higher amount of available food for water organisms in the river (dead leaves, etc.) and more diversity in habitats with those branches and logs that can make natural dams in the riverbeds”.

“Temperatures lower due the shadow of plan coverage on the river and this helps fighting negative effects such as climate change. Also, these positive effects increase if going river up, in particular, regarding riverheads, where riverbanks are small”.

How can we restore rivers efficiently?

Protecting environmental health of rivers and water basins in Europe is one of the objectives of the European Comission Water Framework Directive. In this situation, recovering riparian vegetation was one of the most frequent strategies to stop the impact of agriculture on water systems. However, despite these efforts being made, results are not always the best and it is necessary to find out what factors guarantee a successful restoration. 

“Agriculture and stockbreeding are fundamental economic activities for our society, but have a big environmental impact on rivers. Therefore, we need to find ways to mitigate or neutralize these unwanted effects”, highlights Gutiérrez Cánovas, researcher in the program Juan de la Cierva in the Department of Evolutionary Biology, Ecology and Environmental Sciences of the UB.

Riverbank vegetation: biodiversity, landscape and natural habitat

Regarding this environmental problem, restoring riverbank vegetation is a cheap and simple option, “but we have to bear in mind what the efficient conditions are”, adds the expert. “Effects of repopulation of riverbank vegetation can be variable when stopping pollution effects due high concentration of nutrients or sediments”.
According to the authors, damaged basins due the impact of fertilizers, pesticides and other pollutants, this intervention is not quite effective by itself. In these cases, it would be necessary to develop additional measures at a higher scale (reducing the agricultural surface, implementing low-impact agriculture, etc.).

“Riparian restoration does not solve everything. There is still a long way to go in order to bring health back to damaged rivers, but we know now what to expect from a riparian restoration, and with which cases we can get better results”, concludes Gutiérrez-Cánovas.

The new study was carried out within an international collaboration of the European project Managing aquatic ecosystems and water resources under multiple stress (MARS), coordinated by a team with the participation of Cayetano Gutiérrez Cánovas (UB-IRBio-FEHM).