Victoria's natural ecosystems support thousands of native plant species, hundreds of species of lichens, mosses and liverworts, mammals, birds, fish, reptiles, tens of amphibian species and unknown numbers of invertebrate, fungi and algae species. Many of these species are endemic to Victoria's forests (not found anywhere else).
Victoria's forests occur in plains, coastal, alpine and other environments, and are exposed to natural disturbances, such as fire and insect attack. We have much to learn about the biological diversity of Victorias forests. Many species of mosses and lichens, invertebrates and soil micro-organisms have not been identified properly, let alone had their ecological characteristics understood.
RainforestsVictoria's rainforest communities are our oldest vegetation types. They have existed since Australia was part of the southern super-continent Gondwana (100 million years ago). As Australia moved north and became dryer, eucalypt trees with high fire tolerance dominated the landscape. In Victoria, rainforest only remain in small patches, mostly in cool wet gullies where fire is infrequent. As a result, rainforests are home to a large number of rare and threatened species.
Rainforest are closed broad-leaved forests with a continuous canopy of varying height. Certain types of species make up the character of rainforests. Rainforest canopy species are shade tolerant tree species that regenerate below an undisturbed canopy or in small gaps in the canopy. Gaps occur as a result of small disturbances, such as the loss of a tree due to the wind or lightening. Fire is detrimental to the regeneration of rainforest species.
In Victoria there are four main types of rainforest – dry, cool temperate, warm temperate and gallery:
- Dry rainforest is in an area of variable, but reliable rainfall.
- Cool temperate rainforest usually occurs in cooler, wetter regions. Characteristic rainforest species include Myrtle Beech, Southern Sassafras and Black Oliveberry.
- Warm temperate rainforest is characterised by species such as Lilly-pilly, Sweet Pittosporum, Muttonwood, Yellowwood and Blue Oliveberry. Below the canopy created by these trees, only shade tolerant plants such as ferns, mosses and lichens can grow successfully.
- Gallery rainforest occurs in flood prone stream course on stony soils
Old Growth ForestOld-growth is forest that contains significant amounts of very old trees (senescent forest) which has not been distrubed by fire, timber harvesting, grazing, mining or clearing for agriculture. Old-growth forests usually have a complex structure and a high diversity of plant and animal species. They are important for biodiversity, as some species of plants and animals are specially adapted to this type of forest. They are also the hardest to replace due to the length of time they take to develop.
The common view of old-growth forests is as damp forests with massive eucalypt trees, such as Mountain Ash, and a dense understorey including tree-ferns and other lush vegetation. However, much old-growth occurs in drier forests as much less-spectacular trees. Approximately 10% of forests in Victoria are old-growth forests.
Endangered SpeciesThreatened species and threatened communities of species, are those in danger of becoming extinct if the threat is not removed. Vulnerable species and communities are likely to become threatened if the threat persists. Some forest dwelling species that are threatened include the Leadbeaters Possum, Baw Baw Frog, the Spotted-tail Quoll, Long-footed Potoroo, Powerful Owl and the Swift Parrot. Some species are naturally rare and at greater risk of becoming vulnerable than common species.
Potential threats to species in our forests include:
- habitat distrubance from fires occurring too frequently (or fires that are inappropriate in other ways)
- habitat fragmentation due to disturbances such as land clearing, timber harvesting or fire
- loss of important habitat elements (such as hollow bearing trees or woody debris on the forest floor)
- invasion of pest plants and animals
- silting up of streams from erosion caused by road use
- changing conditions associated with climate change