Swamps of the Blue Mountains

The swamp communities of the Blue Mountains are a geographically dispersed group of ecologically-endangered peat swamp communities, spanning multiple parts of the World Heritage-listed Blue Mountains National Park in New South Wales, Australia.

The swamps were first listed as endangered ecological communities in 2004, under the Environment Protection and Biodiversity Conservation Act 1999 and the Threatened Species Conservation Act 1995 (NSW). The swamp communities are usually found at altitudes ranging between 500 and 1,000 metres (1,600 and 3,300 ft) above sea level. They comprise less than 3,000 hectares (7,400 acres) or around 3% of the total heritage area of the Blue Mountains National park.

It is believed that swamps such as these formed around 15,000 years ago. The Blue Mountain swamps exist within low‐lying sites on valley floors (valley swamps) and also as hanging swamps which occur on steep hillsides and around the headwaters of creeks.

The swamp communities exist with different variability, and may be considered valley swamps, hanging swamps, or a combination of both. Hanging swamps are named for their appearance of literally hanging off cliff faces or steep hillsides. Swamp communities receive water from different pathways, with water coming from groundwater, feeder streams, or a combination of both of these sources.

The valley floor swamp communities form typically because of the predominantly sandstone plateau. This substrate allows the percolation of water in poorly-drained stream headways.

The hanging swamps are formed via groundwater that seeps through permeable sandstone layers, which then as a consequence of the rock composition, is trapped by layers of claystone, ironstone and shale, and proceeds to be channelled to the surface. This process initiates a path of constant moisture, allowing hanging swamps to form peat in an anaerobic environment. The process of thick peat formation takes millennia.

The Blue Mountains on average typically receives greater than 1,000 millimetres (39 in) of rainfall per year; the low subsurface permeability, combined with the slowed runoff, assists in the formation of these biodiverse swamp communities in Blue Mountains.

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