Sedge

Long description

Sedgelands dominated by a range of sedges and grasses including Eleocharis philippinensis, Cyperus alopecuroides, Cyperus scariosus and Cyperus iria and the grasses Sporobolus virginicus and Paspalum vaginatum. The sedges Fimbristylis ferruginea, Phyla nodiflora and Cyperus polystachyos var. polystachyos may occur in the shallower margins, together with Vincetoxicum carnosum. Cyperus polystachyos, Gymnanthera oblonga, Acrostichum speciosum and Centella asiatica in the transition zone between tidal and freshwater areas. These systems occur in depressions on Quaternary estuarine deposits that are brackish to saline[4]

These ecosystems tend to be associated with more freshwater (surface or ground) influence, for example at the landward edge of saltpans and/or on sandier soils where groundwater permeates (such as the upper beach where there is groundwater expression). May be seasonally inundated with freshwater, but dry out completely between rain events. Seaward extent and frequency of tidal inundation depends on freshwater influence (rainfall, groundwater) but can be low in the system and therefore inundated regularly. Strips of sedges occur low down in the tidal area on Fraser Island west coast beaches where groundwater is coming to the surface.

Special values

Can provide habitat for the water mouse (Xeromys myoides), which is Environment Protection and Biodiversity Conservation Act 1999-listed (EPBC-listed). This species has been recorded from coastal saltmarsh ecosystems including saline sedgelands and grasslands, succulent shrublands, mangroves and freshwater wetlands. Water mice are known to hunt amongst mangrove pneumatophores and in shallow pools, for grapsid crabs and other intertidal crustaceans, pulmonate snails and marine gastropods[5].

Habitat for a range of waders and water birds, many of which are EPBC-listed.

May contain pools and often holds back estuarine water in the pools when tide recedes, which are important fish and crustacean nurseries. Marsh crabs are common in sedgelands.

Diagnostic attributes

Inundation 'Intertidal - Lower low’, ‘Intertidal – Mid low’, ‘Intertidal – Upper low’, ‘Intertidal – Low undifferentiated’, ‘Intertidal – Lower medium’, ‘Intertidal – Upper-medium’, ‘Intertidal – Medium undifferentiated’, ‘Intertidal – High’, ‘Intertidal – Undifferentiated’, ‘Intertidal – High undifferentiated’ (although they occur closer to the higher tidal planes which remain unmapped)

Structural macrobiota ('Sedge')

Qualifiers

The Naturalness qualifier is relevant as tidal inundation may sometimes be modified by barriers, and excavated channels, modifying Inundation and Terrain morphology. Changes in tidal inundation will be reflected by changes in Structural macrobiota.

These ecosystems fluctuate in extent over time and relevant qualifiers are Period and Trend. Changing tidal inundation due to sea level rise is causing mangroves to colonise saltmarsh ecosystems (list their numbers)[2].

Distribution

Sedge ecosystems are potentially common associated with areas of freshwater/groundwater expression, e.g. melaleuca swamps and large sand systems, such as from Fraser Island southward (Cooloola, Bribie, Moreton and Stradbroke Islands).

The following relates to distribution of this ecosystem type within the Central Queensland mapping area:

• In Central Queensland mapping sedges occur from Elliott Heads south and are present in the Great Sandy Strait in association with large sand masses (Cooloola/Tin Can, Burrum/Elliott, Fraser, Middle Island near Eurimbula, Baffle) and likely to be in Deepwater but not mapped. Unmapped areas occur within terrestrial Bioregion 12. In Bioregion 12, may also occur in coastal swamps and associated water bodies on Quaternary coastal dunes and beaches. Characteristic species include Gahnia sieberiana, Empodisma minus, Gleichenia spp., Blechnum indicum, Lepironia articulata, Baumea spp., Juncus spp., and Eleocharis spp.[3].
• In the Great Sandy Strait and Wide Bay/Burnett regions, the highest concentration of water mouse nests were recorded in the Kauri Creek catchment and Tin Can Inlet, with nesting in sedgelands adjacent to mangroves[1].
• In Bioregion 12, all saltmarsh ecosystems are EPBC listed (i.e. grass-herb-sedge (1) and other saltmarsh ecosystem types (2, 3, 4 and 17) Curtis Island southward).

Comments

Other relevant attributes include Freshwater input source, Freshwater input volume, Consolidation, Energy and Sediment texture as sedges typically grow on unconsolidated muds and fine sediments in low energy environments.

Additional information

Field Guide to common saltmarsh plants of Queensland

References

1. ^ Burnham, M (2002), New locality records for Xeromys  myoides False water-rat, within the Great Sandy and Wide Bay/Burnett management areas. Results from surveys conducted February to April 1999 and March to May 2000., Great Sandy - Natural Resource Management, Queensland Parks & Wildlife Service, Maryborough.
2. ^ Lovelock, C & Ellison, J (2007), Vulnerability of mangroves and tidal wetlands of the Great Barrier Reef to climate change.
3. ^ Queensland Herbarium (2005), Regional Ecosystem Description Database (REDD), Versions 4.2. (updated March 2005) 5.0 (updated December 2005) and 5.1 (updated June 2007). [online], Environmental Protection Agency, Brisbane. Available at: https://www.qld.gov.au/environment/plants-animals/plants/ecosystems/descriptions/download.
4. ^ Queensland Herbarium & Environmental Protection Agency, B (2005), Regional Ecosystem Description Database (REDD). Version 5.0. [online], Environmental Protection Agency, Brisbane. Available at: https://apps.des.qld.gov.au/regional-ecosystems/.
5. ^ Van Dyck, S & Gynther, I (January 2003), Nesting strategies of the water mouse Xeromys myoides in southeast Queensland. [online] Available at: https://www.researchgate.net/publication/290249920_Nesting_strategies_of_the_Water_Mouse_Xeromys_myoides_in_southeast_Queensland.

Last updated: 19 July 2019