Responses of riparian plants to flooding in free‐flowing and regulated boreal rivers: an experimental study

• Published in: Journal of Applied Ecology
• Main Authors: Johansson, M. E., Nilsson, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2002
• Subjects: Northern Sweden
• Online Access: http://dx.doi.org/10.1046/j.1365-2664.2002.00770.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-2664.2002.00770.x; https://besjournals.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-2664.2002.00770.x

Summary The long history of river regulation has resulted in extensively changed ecosystem structures and processes in rivers and their associated environments. This fact, together with changing climatic and hydrological conditions, has increased the need to recover the natural functions of rivers. To develop guidelines for river restoration, comparative ecological experiments at contrasting water‐level regimes are needed. We compared growth and survival of transplanted individuals of four riparian plant species ( Betula pubescens , Carex acuta , Filipendula ulmaria and Leontodon autumnalis ) over 2 years on four free‐flowing and four regulated riverbank sites in northern Sweden. The species were chosen as representatives of dominating life‐forms and species traits on different elevations of the riverbanks. In Betula and Filipendula , mean proportional growth rates were significantly higher at free‐flowing sites than at regulated sites, whereas no consistent differences between free‐flowing and regulated sites were found in Carex and Leontodon . Differences among species were generally in accordance with natural distribution patterns along riverbank elevation gradients and with experimental evidence on flooding tolerance, although plants of all species survived and even showed positive growth rates on elevations below their natural range of occurrence. Partial least squares regression was used to relate plant performance (growth and survival) to duration, frequency and timing of flooding at the different sites. Flood duration and frequency typically reduced performance in all species and during all time periods, although to various degrees. Flood events early in the experiment determined the outcome to a high degree at all sites. Variables indicating a regulated regime were mostly negatively related to plant performance, whereas free‐flowing regime variables were positively related to plant performance. We used two of the regression models generated from our data with an acceptably high predictive power to ...