4 floristics and structure of saline coastal vegetation
16
chapter 4: floristics and structure of saline coastal vegetation 235 4 floristics and structure of saline coastal vegetation e following chapter provides an outline of the vegetation communities that have been described from saline coastal sites in Victoria. ey cover the range of wetlands and fringing habitats influenced by at least seasonal waterlogging that occur in or adjacent to sites subject to tidal inundation. While at least occasional direct inundation is the primary source of salinity, in some locations the salinity may be maintained by inputs of windborne salt or be residual from earlier times where subsequent geomorphological processes have removed the potential for direct tidal access. e broadly defined EVC 9 Coastal Saltmarsh Aggregate is also reviewed, providing a more detailed resolution of variation within this grouping and a discussion of why this revision is required to properly assess the conservation status of the relevant plant communities. 4.1 Background and data interpretation current evcs relevant to saline coastal vegetation An Ecological Vegetation Class (EVC) is a grouping of vegetation communities based on floristic, structural and ecological features (see Appendix B). e EVCs identified below are currently recognised from saline coastal situations in Victoria. e list includes saline wetlands and the range of communities that fringe Coastal Saltmarsh (but excludes communities of dry dunes and headlands): • Brackish Grassland (EVC 934) • Brackish Herbland (EVC 538) • Brackish Lignum Swamp (EVC 947) • Brackish Sedgeland (EVC 13) • Brackish Wetland (EVC 656) • Coastal Saltmarsh Aggregate (EVC 9) • Estuarine Flats Grassland (EVC 914) • Estuarine Reedbed (EVC 952) • Estuarine Scrub (EVC 953) • Estuarine Wetland (EVC 10) • Mangrove Shrubland (EVC 140) • Saline Aquatic Meadow (EVC 842) • Sea-grass Meadow (EVC 845) • Seasonally Inundated Sub-saline Herbland (EVC 196) • Unvegetated (open water/bare soil/mud) (EVC 990 – ‘Non Vegetation’ 1 ). Spray-zone Coastal Shrubland (EVC 876) occurs in higher energy coastal sites, and also includes halophytic species, but is outside the scope of the report (see Chapter 1.2). e term ‘aggregate’ is applied to an EVC label where the EVC represents a generalised label for wetlands occurring within a given ecological context (e.g. saline, brackish or freshwater lakes; billabongs; mineralised drainage-lines on grey-clay basalt derived soils). While the range of EVCs which can be variously expressed in these situations can generally be determined, the scale and intricacy, and sometimes temporal variation, can 1 Putatively ‘unvegetated’ areas in estuaries are, in fact, almost certain to have diverse microalgal and bacterial assemblages both on and in the sediment. ese microbiota may be ecologically important in the functioning of estuarine ecosystems. As alluded to on the next page, bare mudflats and sandflats oſten provide valuable habitat, especially for wading birds during low tide and for small fish during high tide.
