Identifying biogeographic patterns in Australian saltmarsh and mangal systems: A phytogeographic analysis

Australia is unique among continents in that it has tropical and temperate coastlines stretching the length of the continent (c. 3000 km), connected by western and eastern coastlines, of about the same length. In the interior, there are significant extensive systems of salt lakes, which can remain dry for many years, as well as typically dry depressions in sandy dune systems, dominated by halophilous vegetation. Australia is thus an excellent test bed to examine the effects of climate on phytogeographic patterns in halophytic vegetation. Using two new developments in Australia - the Australian Virtual Herbarium and the Interim Biogeographical Regionalisation for Australia, in combination with previous syntaxonomic work, a new approach to identifying phytogeographic patterns has been developed. This approach produced four main groups for saltmarshes, and eight groups for mangal. The saltmarsh Groups are further divisible into a number of sub-groups. Climate, especially rainfall periodicity and duration, appear the main environmental controls for these Groups and sub-groups. A number of key phytogeographic fulcra are identified for Australia, which target areas where conservation and wise use of these coastal communities should be the priority land use. The analysis will also be helpful in identifying saltmarsh and mangal species that can assist in coastal rehabilitation, and also rehabilitation of degraded or degrading agricultural land, where salinity is the prime cause for degradation.