Mangroves are a common and important feature of the sand flats, river banks and coastlines of the tropics and subtropics of the world. They exist at the interface of two environments: land and sea.
The most luxuriant and diverse mangals are found in the humid tropical regions of the world (Macnae 1968). The present distribution of mangroves suggests that the region between Malaysia and northern Australia was the major centre of mangrove flora evolution (Ding Hou 1958, 1972; Specht 1981). On the fossil evidence, Specht (1981) postulated that the centre of the origin of mangroves is more likely to have been the region from south-western and northern Australia to Papua New Guinea rather than the Malaysian Archipelago.
The present mangrove flora in Australia is one of the richest in the world. Twenty-seven species were classed as mangroves by Beadle (1981), while some 39 species of mangroves were recognised by Duke (1992). Approximately half of the world's mangrove species have been identified in Australia.
Many ecological studies have been conducted on mangroves in Australia from a geomorphological and vegetational perspective including Macnae (1966; 1968), Saenger et al. (1977), Clough (1982) and Robertson and Alongi (1992). However, with the exception of Bridgewater (1985), no studies have attempted phytosociological analyses of these regions.
In this paper, we will discuss some aspects of mangrove vegetation, such as the phytosociological communities in Australia and the biogeographical distribution of mangrove species in East Asia and Australia.