MANGROVES © WET TROPICS IMAGES · 2017-07-31 · Gentle Annie Creek, a tributary on the lower...
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The formation encompasses all woody mangrove vegetation ranging from shrubland to tall open forest, including a number of transitional forest types occurring on the upper tidal reaches of major river systems. In the majority of cases, floristic and structural variations are not differentiated. Association 70a is the most extensive mangrove community which encompasses a complex of closed to open forests, woodlands and shrublands with both structural and floristic variation, organised into distinctive zones. Maximum structural development occurs within the zone of regular tidal exchange, where tall closed forest composed of Bruguiera spp., Rhizophora spp., and Xylocarpus spp. often dominate. Species of lower stature, including Avicennia marina subsp. eucalyptifolia, Ceriops tagal, Aegiceras corniculatum. Lumnitzera racemosa and Sonneratia alba, are often marginal or colonising species, occupying zones of higher soil salinity on landward fringes or as scattered shrubs on exposed mud banks. The prominence and distinctiveness of palms in the canopy of associations 70b and 70c is the basis of their recognition as separate entities. Association 70b is a mixed mangrove forest with emergent Livistona drudei and is restricted to Gentle Annie Creek, a tributary on the lower reaches of the Herbert River. Association 70c occurs on the brackish reaches of Neames Inlet (Herbert River estuary), where a restricted stand of Nypa fruticans is located. Nypa is a palm species that is otherwise restricted to Cape York Peninsula. Mangrove/vine forest complexes are recognised on the upper brackish reaches of the Daintree River where they form a distinctive and consistently mappable fringing forest. Similar communities may be present on major rivers in the super-wet belt (Russell, Mulgrave and Johnstone rivers), although their extent is not sufficient to warrant separation. The association is controlled by the frequent heavy rainfall which flushes any accumulating salinity from soils on riverine banks. The resultant closed forest is a mix of rainforest and mangrove species, where proportions and floristics variations are largely determined by the degree of salinity. Variations range from near pure mesophyll vine forest (1c) progressively intermixing with increasing proportions of Heritiera littoralis, Sonneratia alba, Bruguiera spp. and sclerophyll species including Melaleuca leucadendra and Acacia mangium along a salinity gradient. Facts and figures Vegetation alliances Medium closed mangrove forest mosaics Mangrove vine forest complexes Current extent in the bioregion 44,942ha Area protected 18,511ha (41%) Geography Mangroves forests occur in all areas subject to tidal influence, although their size and complexity is dependent on coastal landform and aspect. The most extensive mangrove forest mosaics are found in the Hinchinbrook Passage area although major occurrences are also found in Trinity Inlet and the Daintree River. Mappable occurrences of mangrove-rainforest complexes are only found on the Daintree River although minor areas may be associated with all river systems in the very-wet rainfall zone. Impacts and changes Major changes are often associated with tidal reclamation which has occurred on a large scale in the Cairns area. Scattered areas of mangrove reclamation occur throughout the coastal portions of the bioregion. The extent, composition and structure of many mangrove occurrences is dynamic, responding to broad scale climatic cycles and temporal variations in regimes of erosion and sedimentation MANGROVES OF THE WET TROPICS BIOREGION Mangrove forests (vegetation codes 70a-70d) © WET TROPICS IMAGES
Transcript of MANGROVES © WET TROPICS IMAGES · 2017-07-31 · Gentle Annie Creek, a tributary on the lower...
The formation encompasses all woody mangrove
vegetation ranging from shrubland to tall open forest,
including a number of transitional forest types occurring
on the upper tidal reaches of major river systems. In the
majority of cases, floristic and structural variations are
not differentiated.
Association 70a is the most extensive mangrovecommunity which encompasses a complex of closed toopen forests, woodlands and shrublands with bothstructural and floristic variation, organised into distinctivezones. Maximum structural development occurs within thezone of regular tidal exchange, where tall closed forestcomposed of Bruguiera spp., Rhizophora spp., andXylocarpus spp. often dominate. Species of lower stature,including Avicennia marina subsp. eucalyptifolia, Ceriopstagal, Aegiceras corniculatum. Lumnitzera racemosa andSonneratia alba, are often marginal or colonising species,occupying zones of higher soil salinity on landward fringesor as scattered shrubs on exposed mud banks.
The prominence and distinctiveness of palms in the canopyof associations 70b and 70c is the basis of their recognitionas separate entities. Association 70b is a mixed mangroveforest with emergent Livistona drudei and is restricted toGentle Annie Creek, a tributary on the lower reaches of theHerbert River. Association 70c occurs on the brackishreaches of Neames Inlet (Herbert River estuary), where arestricted stand of Nypa fruticans is located. Nypa is a palmspecies that is otherwise restricted to Cape YorkPeninsula.
Mangrove/vine forest complexes are recognised on theupper brackish reaches of the Daintree River where theyform a distinctive and consistently mappable fringingforest. Similar communities may be present on majorrivers in the super-wet belt (Russell, Mulgrave andJohnstone rivers), although their extent is not sufficient towarrant separation. The association is controlled by thefrequent heavy rainfall which flushes any accumulatingsalinity from soils on riverine banks. The resultant closedforest is a mix of rainforest and mangrove species, whereproportions and floristics variations are largely determinedby the degree of salinity. Variations range from near puremesophyll vine forest (1c) progressively intermixing withincreasing proportions of Heritiera littoralis, Sonneratiaalba, Bruguiera spp. and sclerophyll species includingMelaleuca leucadendra and Acacia mangium along asalinity gradient.
Facts and figures
Vegetation alliances
Medium closed mangrove forestmosaicsMangrove vine forest complexes
Current extent in the
bioregion 44,942haArea protected 18,511ha (41%)
Geography
Mangroves forests occur in all areas subject to tidalinfluence, although their size and complexity is dependenton coastal landform and aspect. The most extensivemangrove forest mosaics are found in the HinchinbrookPassage area although major occurrences are also foundin Trinity Inlet and the Daintree River. Mappableoccurrences of mangrove-rainforest complexes are onlyfound on the Daintree River although minor areas may beassociated with all river systems in the very-wet rainfallzone.
Impacts and changes
Major changes are often associated with tidal reclamationwhich has occurred on a large scale in the Cairns area.Scattered areas of mangrove reclamation occurthroughout the coastal portions of the bioregion. Theextent, composition and structure of many mangroveoccurrences is dynamic, responding to broad scaleclimatic cycles and temporal variations in regimes oferosion and sedimentation
MANGROVES
OF THE WET TROPICS BIOREGIONMangrove forests (vegetation codes 70a-70d)
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Tenure
Major occurrence on Hinchinbrook Island NP.
Key values
• Important fish habitat and breeding areas
• Important regulators and recyclers of marine nutrient
• Sinks for terrestrial and marine derived sediment anddetritus having a role in the maintenance of marinewater quality
• Erosion protection for coastal and estuarine areas.
Management considerations
• Regulation of aquaculture ventures and other coastaldevelopment
• Mangrove dieback - requirements for research andmapping.
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