Agriculture Reference
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MTV communities in the southwest. He emphasized the role of soil texture/depth
in interaction with rainfall as the overriding determinant of community distribu-
tions. Thus, soils with similar texture and depth may yield differing vegetation
types under alternative rainfall regimes (Burrough et al. 1977 ; Beadle 1981 ; Beard
1984 ; Sparrow 1989 ). Recent insights into varying strategies of acquisition of key
nutrients in low fertility soils (e.g. mycorrhizae, cluster roots, etc.) suggest that
functional specialization could also play a role in fine-scale community patterning
in relation to soil variations (Lambers et al. 2008 ).
Complex mosaics of differing communities can be found throughout MTV
regions of southern Australia, which reflect topographic and soil variations
(Hopkins & Griffin 1984 ; Hill 1989 ; Gill 1994 ; Hopper & Gioia 2004 ). Vegetation
is often arranged as catenae with major community and edaphic boundaries
coinciding (Beard 1984 ; Keith & Myerscough 1993 ; Specht & Specht 1999 ). Water
availability, which is a function of soil depth, texture and rainfall, is crucial in
determining the balance between trees, shrubs and grasses. Treeless vegetation
is typically confined to soils where root growth is impeded due to shallow soils
over rocks, which may be seasonally waterlogged, or heavy clay soils, or
where water may be periodically unavailable, such as deep sand in drier environ-
ments ( < 500 mm average annual rainfall). Shrubby mallee woodlands and shrub-
lands are found in lower-rainfall environments (300-500 mm) on deeper sandy
soils, often interspersed with grassy woodlands on heavier textured loams. Open
forests and woodlands with a shrubby understory are found in higher-rainfall
environments on a variety of soils where drainage and waterlogging do not limit
tree growth.
Fire Regimes and Land Use
Charcoal has been found in Tertiary sediments in southeastern Australia along
with fossils and pollen of MTV taxa (Kershaw et al. 2002 ; Hill 2004 ). Charcoal
fluctuated greatly through time but abundance generally increased in the late
Tertiary and Quaternary (see Fig. 10.9 ). However, studies are largely biased
toward the southeast and there is limited Tertiary data from the MTC regions.
The available record does show evidence of a positive association between char-
coal, climate and vegetation signals throughout the Quaternary until the late
Pleistocene (Kershaw et al. 2002 ; Lynch et al. 2007 ). The arrival of humans may
have partially decoupled fire activity from climate (Kershaw et al. 2002 ; Lynch
et al. 2007 ), resulting in more frequent burning. Such trends have intensified with
population changes in the late Holocene (Hassell & Dodson 2003 ; Lynch et al.
2007 ; Enright & Thomas 2008 ).
Fire history studies indicate complex trends spanning the European occupation
of the continent and the breakdown of indigenous societies in the nineteenth to
early twentieth centuries. Interpretations are controversial (Lynch et al. 2007 ;
Bradstock 2008 ) because of the way signals, such as charcoal in sediments
and fire scars from dendrochronology studies, are interpreted. For example,
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