Randomly spaced line intercepts were taken in 18 relatively mature phreatophyte communities on 300 miles of the Rio Grande in New Mexico. Samples of three stands in each of six geographical areas revealed no regularity in species present, percentages of cover, or height over the entire area. Vegetation of the southern and northern sectors was different. Highly significant differences in tamarisk (Tamarix pentandra) and screwbean (Prosopis pubescens) cover were found in plots within areas. The difference in cottonwood (Populus fremontii) cover within and between plots where cottonwood dominated was nonsignificant. No correlation could be found between pH, total soluble salts, and texture of the soil and dominant species of plants growing in the area. In general, no distinct breaks or ecotones occurred in the composition of the narrow band of river vegetation; it formed a continuum with gradual and almost imperceptible changes between dominant and subdominant species as one moved north or south. Postclimax vegetation has been altered or modified in many areas to produce quasi—permanent or disclimax vegetation. Five classes of phreatophyte vegetation were arbitrarily established, the lowest development consisting primarily of screwbean in the southern sector and the highest of dominant cottonwood above San Antonio, New Mexico. The introduction and escape of tamarisk and Russian—olive (Elaeagnus angustifolia) in the last 50 years have changes the successional stages and ultimate dominants of some communities.

The Murray-Darling Basin in south-eastern Australia contains over 70,000 km 2 of wetlands and floodplains, many of which are in poor condition. In response, Australian governments have committed to a major restoration program, the Murray-

Flood-Plain Zone 1 (Very shallow water table-0-4 ft) Flood-Plain Zone 2 (Shallow water table-4-8 ft) Flood-Plain Zone 3 (Medium water table-8-20 ft) Flood-Plain Zone 4 (Deep water tablebelow 20 ft)

Summary This study compares the effectiveness of using plant species, genera, family or water plant functional group (WPFG) classifications for demonstrating differences in vegetation communities associated with inundation history. Vegetation surveys were undertaken annually for 5 years from 2007–2008 to 2011–2012 at 18 floodplain wetlands. These wetlands are from two geographically separate locations situated along the lower Murray River. Wetlands have different inundation histories and have received varied amounts of environmental water since 2004. All plant species recorded were classified into WPFGs. An inundation classification was determined for each wetland at each survey time based on inundation history and inundation status at the time of survey (wet or dry). This study found that plant species composition at individual wetlands is often unique with few species recorded across multiple wetlands. The use of WPFGs reduced the variability of plant communities between individual wetlands, between the two geographic locations and within inundation classifications. By reducing the variability between samples, broad trends in vegetation responses to different watering histories can be identified. Individual wetlands can develop completely different suites of plant species in response to the same watering regime, particularly when separated over large distances. This variability can reduce the confidence managers have in predicting the plant communities likely to develop in response to prescribed watering regimes. Adaptively applying knowledge gained from monitoring to different wetlands or wetlands in different geographical regions is also difficult if responses are highly variable. This study demonstrates that by classifying wetland vegetation into WPFGs the variability observed between samples can be reduced and the influence of floristic differences between individual wetlands and geographic locations can be negated or lessened. We discuss how the use of WPFGs can assist scientists and managers in demonstrating, predicting and communicating trends in vegetation community responses as a result of different watering regimes. The adoption and application of a consistent approach to the classification of plant species into WPFGs has the potential to enable responses and predictions to watering events to be made across broad spatial scales.

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