The humid southwest of Western Australia is geographically and climatologically isolated. An estimate of 9000 species exist in the southwest and 80% of these are generically and specifically endemic to this region (Marchant, 1998). The vegetation is unique and globally significant. The main aim of this study is to determine the vegetation history and Cainozoic development of the Proteaceae in the southwest of Western Australia.
Currently, little is known on the history of the vegetation in the southwest, including the Proteaceae family (which includes Banksia, Grevillea, Hakea, Smokebush). The available fossil records tend to be discontinuous, providing only snap-shots of past vegetation conditions. Often eastern Australian studies are applied to Western Australia on the assumption that the development of vegetation has taken parallel paths on either side of the continent. It is suspected that the history and development of vegetation in Western Australia is different to the eastern areas of Australia.
Limited palynological investigations of vegetation have been conducted in Western Australia. Those that have been done tend to be focused on the Quaternary and there is far more scope for study. A few palynological studies have been done on Eocene deposits, but these tend to be descriptive taxonomic investigations. This study incorporates the Eocene (a pivotal period in plant evolution) through the Pliocene, into the Holocene and comparing this with the present vegetation has not been done. This research will build on the available knowledge of southwestern Western Australian vegetation and climatic history and provide, in particular, a detailed account of the Proteaceous component of past vegetation.
This project aims, therefore, to understand the patterns of Proteaceae development by investigating three sediment sequences of different ages and a modern pollen rain study from the southwest of Western Australia. Lake Lefroy in Kambalda is a present salt lake and palaeochannel containing Eocene deposits that were accessible through a WMC minesite (ëAfricaí). Yallalie, an infilled meteorite impact site, containing a well preserved Pliocene assemblage was recently drilled for palynological analyses. A selection of several early and late Quaternary sites is being considered at present. Modern pollen rain of Proteaceous rich communities in Fitzgerald River, Stirling Range and Mt Lesueur National Parks is being studied to quantify the patterns of pollen representation of major taxa in relation to present vegetation.
The current concern for management of the environment for biodiversity requires such studies. Little is known about biodiversity and vegetation dynamics of the Western Australian environment (Dodson, 1994). Commonly, only broad conclusions can be made. It is not clearly known what has driven the southwest vegetation communities to develop into biodiverse hotspots. Understanding the forces in the environment that have shaped the evolution of the flora in the southwest will enable present communities to be better understood and managed accordingly.