Mound springs of the Swan Coastal Plain

Assemblages of plants and invertebrate animals of tumulus (organic mound) springs of the Swan Coastal Plain are ecological communities in Western Australia. They have been managed under a number of other, similar names, including Mound springs of the Swan Coastal Plain and Communities of Tumulus Springs (Organic Mound Springs, Swan Coastal Plain). The tumulus mounds were common to a narrow range of groundwater discharge at the boundary of 'bassendean sand' and 'guildford clay', along the edge of the Gnangara Mound aquifer. The communities are critically endangered.

At the edge of the Gnangara Mound, where heavy guildford clays meet the bassandean dune system, bogs and swamps are created by the discharge of water from this aquifer. The clay and sand intersection on the Swan Coastal Plain, near the Darling Scarp, also produces permanent springs, giving rise to peat and sand mounds containing plant and invertebrate assemblages. The continuing vegetative growth produces microhabitat for many species. Penetration of water produced by regional hydrological forces alter and increase the size of the mounds by pushing material to the surface through the peat layers.

Fauna includes relict gondwanan species of invertebrates which are often unique to the remaining mounds. Flora of flooded gums (Eucalyptus rudis), bracken fern (Pteridium esculentum) and rushes (from the plant families Cyperaceae, Juncaceae and Restionaceae) occur around the springs. These are often remnant to climate change of the bioregion and are only otherwise found further south.

Although once common to a narrow range between Guildford and Muchea, only three remain over an area of eight hectares. They are at Ellenbrook, Bullsbrook (Kings Mound Spring) and one near Muchea. Many species are highly adapted to the permanent water habitat and this may offer refuge from climate change for others. Many species are endemic to the tumulus mounds of the Swan Coastal Plain.

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