Since European settlement, the South West has lost almost 75% of its original vegetation cover. Today, losses of native vegetation may be attributed to declines in condition (80%) with 20% being removed through clearing (VEAC, 2011). From the cool temperate rainforests and lowland forests in the Otway Ranges, to the dry foothill forests to the north and Grampians to the west of the region and the scattered grassy woodland and grassland communities that lie between; of the original vegetation that remains, approximately half is now restricted to areas of private land.
As well as changes to the extent of native vegetation, the quality of native vegetation has also declined, due to a history of introduced pest plants and animals, changes to flooding and fire regimes, as well as other human induced practices.
More information on the region’s native vegetation can be found in VEAC’s state-wide investigation into remnant native vegetation at www.veac.vic.gov.au/investigation/remnant-native-vegetation-investigation/reports
Most vulnerable will be communities that currently rely on wet climates with consistently high levels of rainfall. Examples include the rainforests and wet forests of the Otway Ranges and areas around Portland, the riparian communities of the region, especially those currently found along the smaller tributaries that feed into the larger river systems. These vegetation communities are dependent on regular flooding or at least periods of inundation from heavy rainfall events. Examples include the riparian forests and woodlands found in the upper catchments.
Not all vegetation communities will be highly vulnerable to climate change. Communities such as Coastal Scrubs, Salt Tolerant Shrublands and Heathy Woodlands will all be quite resilient to the hotter and drier conditions that are expected to occur. These communities naturally occur under these types of conditions today and therefore have higher thresholds to cope with the expected changes, both in temperature and reduced rainfall.
Climate change will also have other, perhaps greater, impacts on native vegetation through changes to existing fire regimes, with more frequent and intense events projected. This creates serious ramifications to vegetation communities already restricted in extent; either naturally or through fragmentation e.g. native grasslands. It is expected all vegetation communities will need to adapt to these changes. Some may alter their floristic compositions and/or structures others may change their reproductive processes. Many will not be able to adapt and may be replaced by vegetation communities more resilient to altered fire regimes, or by becoming new vegetation communities in their own right.