FLORISTICS AND ENVIRONMENTAL RELATIONS OF INLAND DRY RAIN-FOREST IN NORTH QUEENSLAND, AUSTRALIA

Site-species data were collected from inland dry rainforest of north Q ueensland. The extent of patches declines with distance from the coast and they do not occur where rainfall is less than about 500mm per ann um. TWINSPAN derived eight broad groups and sixteen subgroups of the f loristic continuum of rainforest in the study area. The floristic sub- groups are restricted within regions of the study area and most occur over a wide range of geological substrates and landforms. The primary floristic gradient is related to a latitudinal trend coinciding with t he coefficient of variation of monthly precipitation, and a secondary gradient to distance from the coast and mean annual precipitation. The placement of dry rainforest from the study area within existing schem es is examined and the past terminology of Australian rainforest from relatively dry environments is discussed. Nearly half of the dry rainf orest flora is obligately associated with that environment. Although t he flora is fairly specialized to the rainforest environment, 87% of t he inland woody species inventoried during this study are also known t o occur within 1 km of the coast. It is argued that the widespread nat ure of the flora, the lack of specialization to habitat, and the exist ence of relatively complex dry rainforest on basalt lava flows of late Pleistocene age are consistent with a relatively recent invasion of t his region of Queensland by this vegetation type since drier times dur ing the last Glacial cycle.