Does channelization alter spatial and temporal dynamics of macrophyte communities and their physical habitat?
Rambaud, Maëlle Pavoine; Machon, Nathalie; Moret, Jacques; Combroux, Isabelle
published: Mar 1, 2009
ArtNo. ESP141017402004, Price: 29.00 €
Channelization is the creation of man-made structures that resect, realign, or enclose aquatic systems in order to prevent flooding or to modify their flows for various land uses. The present study examined the impact of this human pressure on the spatial and temporal dynamics of small streams. The physical and floristic characteristics of seventeen reaches in four French rivers were surveyed six times over the course of two years. Macrophyte communities were divided into three biological groups: vascular plants, macroalgae and bryophytes. We used plant functional traits to understand the effects of channelization on community structure. Our results suggest that channelization affected the spatio-temporal dynamic of physical and floristic composition. Channelized reaches were shallower and narrower than non-channelized reaches, i.e. control reaches. They also exhibited different substrate types and dominant species. Differences were mainly observed at the macrohabitat scale, i.e. the pool/riffle scale, within the selected reaches. Alterations in spatio-temporal dynamics of physical and plant composition could be linked to species biological traits. Vascular plants and macroalgae in channelized reaches used a variety of adaptive strategies (e.g. small versus tall size) which allowed them to persist despite environmental differences, whereas plants in control reaches showed a combination of intermediate strategies. Bryophytes were mainly found in control reaches with the exception of Fontinalis antipyretica. These findings could serve as guidelines for future channelization projects and for conservation measures to preserve the dynamics of natural streams.