Mangroves in eastern and southern Australia

Abstract

The floral and faunal ecology of mangrove associations in Australia, particularly those in tropical Queensland, are discussed in this paper. The mangroves conform to a basic pattern of zonation and there may be recognized (1) a landward fringe which may be either (a) forested or (b) colonized by Avicennia and by halophytes; (2) Ceriops thickets; (3) Bruguiera forests; (4) Rhizophora forests; and (5) seaward fringe of Avicennia and Sonneratia. These zones may be modified by the interaction of such factors as rainfall, evaporation, and inflow of freshwater. Where rainfall is well in excess of evaporation the zonation is complete and uninterrupted. Where evaporation is well in excess of rainfall bare areas replace much of zones (2), (1), and (3) in that order and zones (3) and (5) become narrow. Zone (5) is rarely affected. The animals, being forms which live in the shelter and shade of the trees, are affected by this distribution but generally show little or no clear zonation. The animal communities are described and where zonation occurs this is discussed and reasons postulated for this zonation.

Factors Influencing Biodiversity and Distributional Gradients in Mangroves

“…On the eastern coastline, the tallest (up to 35 m tall) and more dense forests of mangroves inhabit areas where mean annual rainfall is > 1500mm and distributed throughout the year. In areas where rainfall is < 1500 mm and seasonal, mangroves are much shorter, around 1-6 m. In these drier areas, there are also larger vegetation-free zones bordering the landward fringes (Fosberg, 1961;Macnae, 1966). In general, the suitability of habitat for particular mangrove species depends on climatic conditions and the coastal geography.…”

Tree Mortality in Mangrove Forests

“…Massive tree mortalities also occur near the latitudinal limits of mangrove distribution due to periodic frost events (Simpson 1932, Egler 1952, West 1977. Temperatures of -3 to -1 ?C have produced heavy defoliation and death in many areas of southeastern United States, southern Australia, and New Zealand (Davis 1940, Macnae 1966, Chapman 1976, Lugo and Patterson-Zucca 1977. An overflight of all mangrove forests in Florida after the 1977 frost, established that massive tree mortality was significantly more severe in the basin mangrove forests where tidal flushing was least frequent (Lugo andPatterson-Zucca 1977, Shines 1979).…”

Vegetational Relationships in the Mangroves of Tropical Australia

“…Our studies in Queensland have been directed towards such an objective at least to the extent that the environmental and floristic diversity of the region permits. We had for guidance, well known studies by Macnae (1966) on the same coastline and a guide to the species by Jones (1971). As reported (Bunt et al, in press), that flora has now been expanded.…”