Sensitive Vegetation Mangrove Forest
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Sensitive Vegetation in the Northern Territory Mangrove Forest Description of vegetation community Historically, the extent of mangroves in Mangroves are found along sheltered tropical the Territory has fluctuated substantially in and subtropical coast lines, growing in tidal response to changes in sea level. areas frequently inundated by saline water. Further periods of changes in sea levels may lead to pronounced changes in distribution. A mangrove community may contain a variety of plants, from trees, palms, shrubs, vines, epiphytes, Why are mangroves significant? samphires, grasses and ferns. The community can Mangroves provide spawning and nursery vary from dense closed forests through to sparse areas for many marine species and protect shrublands and samphire on salt flats. the coastline from erosion during storm surges Mangroves have and cyclones. They also provide a valuable specialised recreational, educational and scientific adaptations resource and are an important part of enabling them to indigenous culture. grow and reproduce under demanding Mangroves support highly specialised animals, conditions. High levels of salt, tidal inundation including many species which occur nowhere and wave action typify these challenging else. Distinctive mangrove birds include conditions. the yellow white-eye, chestnut rail, black butcherbird, mangrove gerygone, mangrove Distribution and global significance robin, white-breasted whistler and mangrove The mangrove communities of Darwin Harbour golden whistler. are amongst the most diverse in Australia, Other distinctive mangrove animals include the making them a significant natural resource false water-rat, mudskipper, mangrove monitor locally and globally. and a group of snakes including the 2 There are approximately 3 800 km of woody white-bellied mangrove snake. mangroves in the Territory. Combined with samphire and saltflats, integral components of mangrove ecosystems, they occupy 9 700 km2 of the Territory’s coastline. In terms of biomass, these mangrove forests represent over 73 million tonnes of woody material, which is approximately 26 million tonnes of carbon (not including soil carbon) - this carbon is equivalent to annual emissions from approximately 8.1 million cars. 2 % world Region Area (km ) mangroves Northern Territory 3 800* 2.4 Australia 14 510 10 Indonesia 30 620 19 World 157 051 100 Mangroves have adapted to growing in conditions of (* Refers to the woody mangrove component only. Not including high levels of salt, tidal inundation and wave action saltpan/saline coastal flat areas ~ 5900km2 of saltflat in NT). For more information visit www.denr.nt.gov.au Mangrove Forest Mangroves are important as nursery sites discharges, pesticide runoff and rubbish. for many fish species and the commercially Mangroves are also vulnerable to pollution important delicacy, mud crabs. from ocean sources such as rubbish, discarded fishing equipment and oil. Riverside mangroves Mangroves provide important permanent and may be vulnerable to attempts to exploit water temporary habitats for a large number of marine by damming. and land animals. Marine animals commonly found in mangroves include snails, clams, What can we do to octopus, crabs and prawns, a wide range of fish conserve mangroves? and the saltwater crocodile. • Limit disturbance Although there are some threatened species and development recorded in mangroves, there are none that in coastal areas. occur primarily in this habitat type. A wide range You can make a of animals living on the land use the mangroves difference by: as an extension of their habitat, including native • rats, possums, bats, reptiles, frogs and birds. Preventing landward and seaward pollution Acid sulfate soils from boats and ships. Mangrove communities are associated with Mudcrab • Reducing the amount of thick semi fluid mud. This mud has been formed sedimentation entering waterways and by the build up of fine soil particles which have coastal areas by controlling erosion. been transported in creeks and rivers over many years. If disturbed, this mud has the potential to • Controlling weeds and feral animals. become acidic. References and Further Reading Acid sulfate soils are the common name given Land Clearing Guidelines to soils containing iron sulfides. When these nt.gov.au/property/land-clearing/apply-to-clear- sulfides come into contact with air, for example freehold-land through clearing or excavation, they oxidise to form sulfuric acid. Sites of Conservation Significance nt.gov.au/environment/environment-data-maps/ Acid affects the health of fish, plants and many important-biodiversity-conservation-sites/ other animals. The sulfuric acid produced conservation-significance-list can also dissolve many man made materials including concrete, steel and some metals. Threatened Species denr.nt.gov.au/about/flora-and-fauna-division Threats to mangroves Development in coastal areas, such as Darwin Northern Territory Planning Scheme Harbour, has the potential to alter the ecological nt.gov.au/property/building-and-development/ balance of mangrove communities. Some areas northern-territory-planning-scheme of mangroves have been reclaimed (cleared and Other Fact Sheets in this series filled) to make way for residential and industrial Monsoon Rainforest estates, marinas and wharf precincts. Sandsheet Heath The accumulation of sediments in mangroves Old-Growth Forest can be greatly increased by upstream Riparian Vegetation disturbances, including clearing of vegetation Further Information and construction. Department of Environment Increased levels of silt and soil in mangroves can and Natural Resources lead to decreases in water quality and lowered dissolved oxygen levels. These impacts can Rangelands Division destroy plant and animal life, and subsequently Ph. 08 8999 3631 impact on food webs. nt.gov.au/environment/soil-land-vegetation/ native-vegetation Many types of pollution can affect mangrove communities. Landward pollution sources include Rangelands Division stormwater runoff, sewage discharges, thermal Ph: 08 8995 5000 denr.nt.gov.au/about/flora-and-fauna-division 31 January 2018 Page 2.