Illawarra and south coast lowland forest and woodland ecological community

Status: Critically Endangered on the EPBC Act list

The Illawarra and south coast lowland forest and woodland comprises eucalypt forest or woodlands, which can have a grassy ground layer and/or a shrub layer as well as a small tree layer. The distribution is patchy, with the remaining occurrences mostly on lowland sandy loam, loam or clay loam soils around Wollongong to Shellharbour, Milton, Bawley Point and Moruya.

Government evidence of impact of climate change:

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  • Approved conservation advice (incorporating listing advice) for the Illawarra and south coast lowland forest and woodland ecological community

    Climate change In the long term; climate change is likely to change the character of the community by altering resource availability and the competitive relationships between species.

    In general; use locally collected seed where available to create an appropriate canopy and diverse understorey; however; choosing sources of seed closer to the margins of their range may increase resilience to climate change.

    It also interacts with other disturbances or threats to the community; including climate change; feral animal behaviour and weed invasion.

    For example; the frequency and intensity of fire may influence the level of shrubbiness; or floristic elements such as the abundance of mesic species; for example; Pittosporum species or Imperata cylindrica (blady grass).

    For EPBC Act approval; changes in use of the land that falls within the buffer zone must not have a significant impact on the ecological community; but there are exemptions for continuing use (e.g. cropping; grazing or maintaining existing fire breaks).

    The nature of some areas of the ecological community may have changed structurally due to clearing; followed by re growth that is likely to have been subject to an altered fire regime; and often to livestock grazing at some stage.

    Fire Fire regimes have been changed throughout the region; in association with agriculture and urban development.

    Too frequent fire may reduce the ability of some plants to regenerate by killing immature plants; leading to reduced diversity; a more open structure; drier fuels; and increasing dominance by flammable grasses and bracken fern.

    For example; the occurrence or absence of fire is likely to change the susceptibility of a patch to weed invasion and affect the hunting behaviour of predatory animals.

    Fire Fire is one of the primary shapers of ecological communities within the range of the Illawarra and south coast lowland forest and woodlands; with fire regime characteristics such as frequency; burn size and intensity influencing floristics; structure and other habitat features; as well as directly affecting fauna.

    Fire frequency and intensity; and the interaction with fuel; weather and topography is particularly important in defining the transition to rainforest dominated vegetation (Mills; 1993 Mills and Jakeman; 1995).

    Absence of fire in the ecological community can lead to the increase in the density of the shrub layer; with mesic invaders such as Pittosporum undulatum and weeds such as Lantana camara becoming more common.

    Infrequent fire can also threaten species such as the threatened Illawarra greenhood orchid if it allows vigorous understorey growth; crowding out the orchid; which is only seasonally present.

    Amongst the many inferred effects of the decline of digging fauna is the potential for fire intensity to increase; due to the higher above ground fuel loads (previously incorporated into the soil) (Fleming et al; 2014).

    Long established land uses; such as grazing within the range of the ecological community; have a range of lasting effects including soil compaction; change in nutrient profile; weed infestation; loss of understorey; as well as changes to the fire regime.

    Fire frequency and intensity; and the interaction with fuel; weather and topography is particularly important in defining the transition to rainforest dominated vegetation (Mills; 1993 Mills and Jakeman; 1995).