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Natural
Ecosystems -
Dry Forests and Woodlands
The
formation of the Great Divide about 3 million years ago created a barrier
to the moisture-laden winds that sweep across Victoria from the Southern
Ocean. Rainfall is greatest on the southern slopes of the Divide and other
mountainous regions, leaving the northern slopes, foothills, coasts and
plains relatively dry. In this drier country, a variety of eucalypts,
cypress-pines and casuarinas form open forests and woodlands, with grassy,
heathy, sedge-rich or herb-rich understoreys. Stringybark forests dominate
the near-coastal landscape east of Western Port; red gum forests survive
along major rivers in the north of the State; grassy woodlands are scattered
throughout the Western District; and the remnants of the once great box–ironbark
forests lie in a wide arc from west of Stawell to east of Wangaratta.
Much
of Victoria’s dry forests and woodlands are significantly diminished compared
to pre-European times. The more fertile areas were cleared for agriculture
in the 19th and early 20th centuries, and large tracts were laid bare
during the 19th century gold rushes, when timber was in huge demand for
mines, railways and townships. Many of the grassy coastal forests were
also cleared for agriculture, and more recently for urban and recreation
development. The remnants of these once-extensive forests and woodlands
form a mosaic of natural vegetation in a vastly altered landscape, following
patterns of soils, geology and landform.
Dry
forest and woodlands are no less rich or biologically significant than
their wetter relatives. The box–ironbark forests, for example, support
a wide variety of plants and animals, including some of the State’s rarest
orchids, as well as significant mammals such as the Brush-tailed
Phascogale and a range of reptiles. Old and dead trees are essential
habitat for a large suite of fauna in dry forests and woodlands, because
they provide prolific hollows and nectar, thick bark and fallen limbs.
Many birds depend on nectar for food, travelling large distances to feed
in trees and shrubs at peak flowering times. For example, the Swift
Parrot migrates from Tasmania in winter just to feed on flowering
eucalypts in this ecosystem.
Many
species, such as the Grey-crowned
Babbler, Brush-tailed Phascogale and Bearded Dragon, prefer to forage
for invertebrates in rotten wood or under thick bark on large dead or
living trees. Others find food and shelter among branches and leaf litter.
Mistletoes, lerps, honeydew and plant exudates also provide a significant
source of food for animals. Ephemeral streams and soaks support frogs,
invertebrates and birds.
Agricultural
clearing, mining, timber harvesting, firewood collection and gravel extraction
have resulted in significant habitat modification. Current management
challenges include habitat fragmentation and modification, vegetation
clearance, the loss of hollow-bearing trees, weed invasion, feral predators,
introduced pathogens, and improving fire management.
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