Dam removal effects on riparian vegetation
(English)Manuscript (preprint) (Other academic)
Dams cause substantial damage to stream and river landscapes, especially because of flow regulation and channel fragmentation that constrain environmental structures and processes. Dam removal, on the other hand, initiates succession of plant communities as a response to new morphological and hydrological conditions in the channel. We studied the vegetation in riparian reaches upstream and downstream of a dam construction in the Nissan stream in southern Sweden before and after its removal, using a Before-After-Control-Impact (BACI) design. We monitored the vegetation and different environmental variables at three different water levels (summer low, middle and spring high) in the impoundment, downstream of the dam, as well as in an unimpacted reach located within the same river system upstream of the area affected by the dam. Following dam removal, plant colonisation was fast on newly exposed soils in the former impoundment and species richness increased slightly without major changes of the dominant species. The reach downstream of the dam exhibited minor changes after dam removal, comparable to those in the reference reach. The vegetation response implies that the post-removal vegetation in the impoundment area was more similar to that of the previous impoundment than to that of the reference reach, suggesting low seed rain and local recruitment.
dam removal, riparian, plant species, stream restoration, BACI, Sweden
Research subject Ecological Botany
IdentifiersURN: urn:nbn:se:umu:diva-55564OAI: oai:DiVA.org:umu-55564DiVA: diva2:527465