Australia: The Land Where Time Began

A biography of the Australian continent 

Australian Tertiary Phytogeography - Palynoflroas - Palaeocene

At this time the vegetation was dominated by podocarpaceous gymnosperms that formed a significant  and diverse component of the vegetation. There was also a minor component of Myrtaceae, Casuarinaceae and Nothofagus, as well as other diverse angiosperms. The climate was probably cool temperate, similar to that of Tasmania at the present, as indicated by the vegetation at Princetown during the Palaeocene (Harris, 1965).

At Bombala in the southern highlands, the floras are believed to be slightly younger those at Princetown in the Late Palaeocene. As at Princetown, podocarp pollen is dominant, and there is a variety of angiosperms, that includes low numbers of Casuarinaceae, the main difference being the greater numbers of Nothofagus pollen. Another difference is the absence of Myrtaceae and reduced abundance of proteaceous type. The interpretation of the pollen record at Bombala is that it indicates temperate rainforest. The suggested annual temperature is 14-20o C, and the suggested annual rainfall is 1200-1400 mm. The trees grew in a uniform, favourable environment, based on evidence from tree ring analysis, growth being slow and there was an abrupt end to the growing season, but they don't appear to have been affected by droughts or frosts. The palaeolatitude of these forests is 57o S, where there would have been a large seasonal variation of day length, though light availability was apparently not limiting. As occurs in dense forests, the growth rings are complacent (Taylor et al., 1990).

At Mount Royal Range, north of Bombala, also of Late Palaeocene age, the dominant pollen type is gymnosperm, with a less diverse angiosperm flora, and Nothofagus is absent (Martin et al., 1987).

Sources & Further reading

H.A. Martin in Hill, Robert S., (ed.), 1994, History of the Australian Vegetation, Cambridge University Press.

 

 

 

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                                                                                           Author: M.H.Monroe  Email: admin@austhrutime.com     Sources & Further reading