Tidal Wetland Flora of New Caledonia

This report provides the most comprehensive record to date documenting the halophyte flora of New Caledonia. This flora forms a unique assemblage of mangrove and saltmarsh (tidal wetland) plants. Based on extensive field observations gathered during November-December 2006 and December 2009, we present this account of the diversity, biogeography and ecology of all tidal wetland species found on the main island of Grande Terre. The report is comprised of five major parts: 1) a species list identifying 40 tidal wetland species, being 16 saltmarsh and 24 mangrove species (Table 1); 2) a scientific key to species for identification of the 40 tidal halophytes identified in the current surveys, accompanied by distribution maps for each; 3) information on selected morphological and ecological characteristics of key taxa, providing a broad understanding of the origins and dispersal affiliations of these halophyte taxa; 4) a revision and update of mangrove upriver checklists within major estuaries of New Caledonia, from those presented by Duke (2007) – to reveal patterns of upstream distribution with salinity gradients; and 5) species checklists for 82 major field collection sites around the island (Appendices 1, 2 & 3). With respect to the key published accounts of New Caledonian tidal wetland flora (Forster 1786; Saenger et al. 1977; Schmid 1981; Ellison 1995; Lowry et al. 1998, 2004; Jaffre et al. 2001; Morat et al. 2001; Munnzinger & Lebigre 2005), the data presented in the current report offers new observations and descriptions for individual species and their distributions around the island of Grande Terre. The most recent account of tidal halophyte diversity and distribution was by Munzinger and Lebigre (2005), based their assessment of local Herbarium collections and records. Munzinger and Lebigre (2005) reported 22 mangrove taxa (3 of these were not recorded in the current surveys) occurring in New Caledonia (including species and hybrids), a notable increase from the 16 species recorded a decade earlier by Ellison (1995). Our data confirms much of that reported by Munzinger and Lebigre (2005), and our new observations extend on their findings. This report provides a clear definition and description of distinctive tidal saltmarsh plants of New Caledonia. The study also enabled a review of species previously listed and includes the clarification of a reported misnomer in species listings, with the identification of Enchylaena tomentosa (previously Kochia hirsuta). Such revised descriptions provide further insights into the biogeographical linkages between the flora of New Caledonia and Australia and specifically the radiation of Gondwanan Chenopodaceae. Previously, E. tomentosa was described as an endemic species of Australia. However, the findings of this study emphasise the need for further clarification within species groups. This is of particular note for the genus Suaeda, where it is likely the entity present is endemic to New Caledonia.