Geology and landform features
The Dandenong Ranges are the remains of an ancient volcano. Weathering and the action of creeks has eroded the old volcano over time so much, that it is not recognisable today. The whole range is separated from other mountains and is much older than other volcanic areas in Victoria.
About 300 million years ago over a period of time a large volcano erupted near the township of Olinda, creating four very obvious lava flows. The weight of all the lava spewing out of the crater was so heavy that the crater collapsed in on itself and blocked up.
The Ranges that formed from the volcano eruptions rise steeply on the western side and the eastern side has slopes that are more gentle and have streams that flow north to the Yarra Valley (Yarra River) or south to Port Phillip Bay (Dandenong Creek becomes Patterson River).
The Dandenong Ranges have a much higher rainfall than surrounding areas. This has had a big influence on how landforms are made and what types of plants grow here.
In many areas of Melbourne it is possible to view the Dandenong Ranges. The national park is an important part of the landscape backdrop of metropolitan Melbourne. Activities such as large scale land clearing or building highly visible structures can change the look of the mountain range. It is important to protect this visual appeal.
Rivers and Catchments
The national park forms part of the water catchments of the Yarra River and Dandenong Creek and has a big influence on the amount and quality of water flowing into these catchments.
A large part of the Dandenong Ranges is not connected to a sewage system and on-site methods like septic tanks are used to treat household waste water (from the kitchen, bathroom and toilet). Many of the septic tanks are so old that they don’t treat waste water very well and it flows out on the property or to stormwater drains. In many areas, stormwater from roads and homes is not collected in underground drains (like street gutters) and often flows out in sensitive natural areas.
The effect of waste water and storm water has serious long-term impacts on the park. Many urban areas are located on top of the range and the water drains down the hill into the park. The waste water is rich in nutrients, carries weed seeds, which results in the spread of weeds along drainage areas and can kill trees because of waterlogging the soil and adding too many nutrients.
Over the past few years improvements have been made. For example road drainage has been improved on Sherbrooke Road, Churchill Drive, and the Sassafras Kindergarten car park. Grants Picnic Ground and Kallista Primary School have removed septic tanks and have been connected to the sewage system.
Water authorities have programs to encourage people to remove septic tanks and connect to sewage systems. Solving the problem of waste water on the Dandenong Ranges has many technical challenges of building sewage systems and has a huge financial consequence.
Even though it is quite small in size the national park has a wide variety of plants. This ranges from small pockets of Cool Temperate Rainforest in the southern gullies to large areas of Grassy Dry Forest on the western slopes.
There are 440 species of native plants recorded in the park. There are 20 plant species listed as Threatened in Victoria, including 3 that are protected under the Flora & Fauna Guarantee and 5 which are also threatened nationally.
The park is especially important in protecting two particular species: the Slender Tree-fern and the Mountain Bird-orchid.
Based on a survey in 2002, nearly 75% of the park’s vegetation was considered to be in good condition, only 8% considered as being in poor condition. Because of the long and complex park boundary (more than 120km) there is a big threat from weeds getting into the park from residents’ gardens.
The park is famous for its cool, damp Mountain Ash forest which surrounds or is near urban areas such as Kallista, Belgrave and Sassafras. On the western slopes there are drier and more flammable forest types. The age of existing forest varies throughout the park but some areas are estimated to be about 250 years old. In areas where there has been recent bushfires the forest is much younger. For example the Mt Ash trees in Sherbrooke Forest grew after a fire in 1922 and are about 90 years old.
The ‘old growth’ forests like Sherbrooke provide very important habitat for wildlife.
The park has a range of fauna species, including:
- 130 species of native birds
- 31 species of mammals
- 21 species of reptiles
- 9 amphibians
The park has 14 fauna species listed as Threatened in Victoria including the Tree Goanna and Broad-toothed Rat, and 11 which are listed under the Flora & Fauna Guarantee. The park is especially important in protecting two species of amphipod. Breeding populations of threatened large forest owls such as the Powerful and Sooty owls are located in the park. It is also home to regionally important, but not threatened, animals such as the Superb Lyrebird and Black Wallaby.
The park is well known for its population of lyrebirds. Although lyrebirds live in many other parts of Victoria, this is the closest location to Melbourne where they can be seen in their natural habitat. Since European settlement the population has declined due to destruction of habitat through land clearing for housing and farming, fire and weed invasion and from the significant impact of feral animals, particularly foxes. Lyrebirds were also killed for their feathers which were used in lady’s fashion in the 1800s.
Since 1989 a predator control program was created, together with pest plant control and repairing damaged habitat. These programs have resulted in an increase in lyrebird numbers and the lyrebirds now live in more areas of the park. Community groups have played a big role in both monitoring populations and restoring their habitat.
Wildlife feeding is prohibited in all national parks in the state however it is permitted at Grants Picnic Ground in the Dandenong Ranges National Park. This is allowed because of the long-term lease of the cafe owners. Bird feeding has caused an unnatural population of birds to live there. The Sulphur-crested Cockatoos are the ‘bullies’ of the forest and take most of the food and tree hollows for nesting. This prevents other parrots, such as Crimson Rosellas, King Parrots and Galahs, from living in this area in higher numbers.
The most significant risk of bird feeding is that diseases carried by the birds can be passed to humans. Feeding is only permitted in the Bird Feeding Zone at Grants and visitors are provided with a hand cleanser and wash basin to clean their hands with afterwards.