OFR 151.pdf - CRC LEME

Australian ‘biomes’
Although biome terminology is widely used in Australia, the vegetation is more usually
classified in terms of formations made up of distinct communities or associations. For
example, Specht (1970) has used plant community structure (height and spacing of the
dominant stratum) to classify the vegetation (Table 2). Particular types have been further
subdivided using other characters. Webb (1959, 1968) and Webb et al. (1984) have used leaf
size and structural relationships to subdivide rainforest formation growing in regions with
adequate rainfall in all seasons but subject to different temperature regimes.
A number of the terms used to qualify temperature regimes, viz. tropical, subtropical
(paratropical), temperate, subalpine and alpine, have geographical as well as thermal
connotations. In recognition of this, Nix (1982, 1991) has proposed an ecophysiological
classification, which relates plant growth response (and therefore competitive ability) to the
major climatic variables of insolation, air temperature and seasonal precipitation. Three
major thermal response categories are distinguished (mean air temperatures in parentheses)
where precipitation does not limit plant growth in any season – megatherm (>24 ° C),
mesotherm (14 ° C -24 ° C) and microtherm (24 0 C arid arid < 300 mm pa
* These values differ that those inferred by Wolfe (1987) from temperature relationships
of major forest types in East Asian forests (Figure 2), which may be more appropriate
for warm periods during the Palaeogene.
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