11 March, 2012

Growing concerns

Animals are not the only introduced species to be found along the Barwon. With the arrival of European settlers came a wide variety of plants, some provided food, some were ornamental, some no doubt arrived unintentionally and many became weeds in their new environment.
I've mentioned deforestation along the Barwon and its tributaries in previous posts - especially as its effects relate to water catchment and the ability to withstand bushfire in the Otways. Another problem with the loss of native vegetation is the loss of habitat and food sources for wildlife. If eucalypts are cleared instead of being allowed to age naturally and die, those birds and other animals such as Red-rumped Parrots which nest in tree hollows will struggle to find suitable sites in which to build.
Dead tree with hollow branches used by nesting Red-rumped Parrots at Fyansford
Native re-vegetation at Barwon Valley
Birds like the various honeyeaters which rely on the nectar from native plants may be adversely affected by a lack of flowering native trees and shrubs - for instance the White-plumed Honeyeater has a close association with River Red Gums. On the other hand, many of these birds (along with the various introduced species) may also benefit from the presence of exotic flowering plants and fruit trees.
Introduced prunus in bloom near Breakwater
Whilst re-vegetation efforts in recent years have aimed to increase the presence of native plants along the river - especially through the urban areas - there are still many remnants of 19th century plantings along the riverbank.
Apple tree growing wild on the banks of the West Barwon
River below the West Barwon Dam

Cyprus tree on the riverbank at Barwon Valley
Apple trees remaining near the West Barwon Dam are one example of introduced plantings as are cyprus trees found at various points along the river through Geelong. Another is the few remnant willow trees which still grow along the river bank through Geelong. These willows are the last survivors of a string of 19th century plantings stretching from town to the breakwater. Ironically, they were planted in an attempt to control erosion along the riverbank. In actual fact, the opposite may be true as the root masses formed by willows can inhibit fast-flowing water, causing erosion. They can also prevent water flow and the growth of other aquatic plants important to native fauna.
Willow tree below Barwon Grange, Newtown

Willow and other exotic plantings below the breakwater
Despite this, I still love the look of willow trees hanging over the water.

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