Abstract
ABSTRACT River regulation can isolate the river channel from its floodplain, reducing flooding and causing vegetation to decline. Inundating isolated floodplains with environmental flows can re-invigorate natural vegetation suffering from hydrologic alteration. The floodplain between Locks 5 and 7 along the lower River Murray in South Australia was inundated in summer 2005–2006 by a managed weir-pool surcharge. We observed a highly variable response to inundation in the frequency and spatial distribution of the perennial floodplain herb, Centipeda cunninghamii (common sneeze-weed). Generally, there was little change in C. cunninghamii abundance or distribution prior to the surcharge. At most sites, C. cunninghamii frequency declined immediately after the surcharge, presumably as existing plants died due to prolonged inundation. At one site, C. cunninghamii did not recover and disappeared. At the other sites, C. cunninghamii re-grew, either in the same location as it was prior to the surcharge, or on a different part of the floodplain. However, at these latter sites, C. cunninghamii tended to recolonise its original location in less than two years. The use of regulatory structures to reconnect river-floodplain ecosystems should be used more widely as this can have a positive environmental impact by altering both floodplain vegetation frequency and distribution.
Published Version
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