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Development of an integrated long-term mangrove monitoring program for Darwin Harbour. Sub-project A: Mangrove community mapping: Charles Point to Gunn Point 2016



Development of an integrated long-term mangrove monitoring program for Darwin Harbour. Sub-project A: Mangrove community mapping: Charles Point to Gunn Point 2016

Other title

Sub-project A: Mangrove community mapping: Charles Point to Gunn Point 2016


Brocklehurst, P; Edmeades, B; Northern Territory. Department of Environment and Natural Resources. Rangelands Division


Hill, J.V.


E-Publications; E-Books; PublicationNT; DENR Technical Report 19/2018




Darwin Harbour; Shoal Bay


This report describes the updated mangrove communities for the approximately 32,000 ha of mangroves and salt flats that line the foreshores of Darwin Harbour, Shoal Bay and areas south of Charles Point and Gunn Point. Results indicate that there has not been any significant, discernible or substantive changes in mangrove forest composition in Darwin Harbour between 1996 and 2016.

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Made available via the Publications (Legal Deposit) Act 2004 (NT)

Table of contents

1. Introduction; 2. Objectives; 3. Methods; 4. Results and discussion; 5. Conclusion; 6. Recommendations; 7. Bibliography; 8. Appendix.




Mangroves; Mangrove community mapping; Map unit; Vegetation mapping

Publisher name

Northern Territory Government

Place of publication



DENR Technical Report 19/2018


x 77 pages; colour illustrations and maps; x 30 cm

File type





Attribution International 4.0 (CC BY 4.0)

Copyright owner

Northern Territory Government



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Mangrove Monitoring Project: Sub-project A 35 8.1.2 Map Unit Descriptions Rhizophora stylosa Dominated Shoreline Forest Communities Generally, mono-specific stands of Rhizophora stylosa occur on the seaward margins of the main tidal mudflats. Structurally, four types have been mapped. Although they are floristically similar, differences in height, habit and locale exist. Where slopes are gently inclined, on the seaward margins of the main tidal mudflats, the low to mid-high Rhizophora stylosa forests (6 - 18 m) occur (map units 1a-1b). These forests generally have straight and clear boles for much of their trunk. In areas with moderate slopes, tidal banks, and at tidal creek mouths, the Rhizophora stylosa forests may form dense entanglements (low shoreline forest tangles) from 4 - 10m tall (map unit 1c). This community formed dense entanglements making it difficult to distinguish between prop roots, trunks and branches. On rocky shores Rhizophora stylosa trees were often multi-stemmed and reached a maximum height of 4 m, mapped as 1d. All four categories of the Rhizophora stylosa forest communities occupy a similar low tidal habitat where tidal inundation is twice daily. At the seaward margin, either bare mudflats or an open-forest of Sonneratia alba is common. When present, the boundary between the two forest types is distinct. In some areas, possibly due to erosion of mudflats, a small too steep bank can occur on the seaward margin of the Rhizophora stylosa forests. Further up the tidal arms and creeks, tidal creek communities (map units 2a-2c) replace Rhizophora stylosa communities. The landward edge of the Rhizophora stylosa forests grade into the Rhizophora stylosa/Bruguiera spp./Ceriops spp. forest communities (transition forest). Substrates are generally bio-turbated and root structured homogeneous muds with slopes of 2 - 5. Small drainage channels 0-0.5 m deep occur across the mudflats. The four Rhizophora stylosa map units described below are equivalent to Darwin Harbour mangrove map unit 1. The use of the 2016 digital aerial photography allowed for better definition and resolution compared to the original Darwin Harbour mapping.