Plant community responses to wetting and drying in a large arid floodplain

The flow regimes of large and river catchments are amongst the most variable in the world. Plant communities which inhabit and floodplains typically exhibit high spatial heterogeneity and are temporally dynamic in response to changing flow conditions. It has been suggested that and floodplain ecosystems, adapted as they are to variability, will be relatively resilient to anthropogenic alterations to flow. This paper argues that floodplain plant communities in and catchments, as in temperate and tropical regions, are primarily structured by flow regimes despite their inherent unpredictability. Consequently, changes to flood pulses through water extraction can be expected to result in changes in vegetation composition and structure which in turn may have a dramatic effect on wider ecosystem functioning. Results are presented from an ongoing study of the Cooper Creek floodplain in central Australia which illustrate the relationships between plant community dynamics and variable flood pulses. These results indicate that alterations to flow may result in a shift in community structure and an eventual loss of bio-diversity. It is essential, therefore, that water resource managers in and regions consider the requirements of floodplain plant communities when allocating environmental flows. Copyright (C) 2003 John Wiley Sons, Ltd.