Coastal mangrove wetland productivity and management, Darwin Harbour, Northern Territory, Australia

  • Bradley William Tweedie Comley

    Student thesis: Masters by Research - CDU


    Mangrove associations have been identified as an integral part of the Northern Territory's coastal eco-system. While studies have been conducted to determine the extent and species diversity of these associations, limited research has been conducted into mangrove productivity.

    Research outlined in this paper has led to the development of allometric relationships between diameter at breast height and total tree biomass, including both above and below ground portions, for the species Avicennia marina, Bruguiera exaristata, Ceriops to gal and Rhizophora stylosa. These relationships were established after processing the above ground biomass of SI stems and below ground biomass of 39 stems.

    The successful development of these non destructive sampling techniques has allowed the calculation of standing biomass estimates for the dominant mangrove associations within Darwin Harbour. In total 22 sampling sites were established, along 7 transects, within 6 different mangrove associations. Association biomass was found to range from 69.63 f/ha for High Tidal Flat associations to 267.29 f/ha for Shoreline Forests. Darwin Harbour total standing biomass has been estimated at 2,727,638 tonnes. The major contribution being made by Tidal Creek associations recording 1,340,715 tonnes, equivalent to approximately 50% of Harbour standing biomass.

    Consecutive calculations of standing biomass has allowed for estimates of biomass accumulation to be established. Biomass accumulation ranged from 4,157 kg/ha/year for Transition associations to 11,346 kg/ha/year for Tidal Creek associations. Total Darwin Harbour biomass accumulation was estimated at 126,085 tonnes per year equivalent to approximately 5% of Darwin Harbour standing biomass. When compared with leaf litter fall estimates calculated by Metcalf (1999) at the some sampling sites it was shown that biomass accumulation was on average equal to that of leaf litter fall.

    Mangrove productivity estimates, established when biomass accumulation was combined with leaf litter falls ranged from 8.9 to 19.7 t/ha/year. Harbour productivity was estimated to be equivalent to 237,990 f/year approximately 10% of harbour standing biomass. The establishment of these estimates now provides for the opportunity to development future mangrove management practices that will take into consideration the impacts of development on mangrove productivity.
    Date of AwardSep 2002
    Original languageEnglish
    SupervisorKeith Mcguinness (Supervisor)

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