Mangrove forest productivity and biomass accumulation in Hinchinbrook Channel, north Queensland

Brief description

In November 1996, three sites were selected along Hinchinbrook Channel, which represented the major forest types and environmental range within the channel. Six plots, each usually 400 m² were marked out at each site and all trees were tagged, identified to species level and the diameter at breast height (DBH) was measured. The biomass of each tree was estimated using previously established allometric relationships between DBH and biomass. The two year time span of this project was insufficient to reliably measure biomass accumulation within these plots. Estimates were obtained from permanent plots in Missionary Bay, which had a 5 year record. Below ground biomass accumulation was calculated using the relationship between above-ground and below-ground biomass derived for Rhizophora apiculata in Malaysia.The forest canopy was accessed from steel towers, up to 10m in height, constructed in three forest stands with different species compositions. From top to bottom, a 2x1 m section of the canopy was divided into horizontal layers of 0.5 m thickness. Within each layer, in two of the stands, (a mixed stand of Bruguiera gymnorhiza/Rhizophora stylosa and a mixed stand of Rhizophora apiculata/Rhizophora stylosa), the angle of each leaf was measured and leaves removed to measure area and dry weight. The measurements taken were used in the simulation of canopy light profiles. In all plots, indirect estimates of canopy leaf area index were obtained from measurements of light flux density with a quantum sensor.Photosynthetic rates were determined for Bruguiera gymnorhiza, Bruguiera parviflora, Ceriops australis, Ceriops tagal, Rhizophora apiculata, Rhizophora lamarkii, Rhizophora stylosa, Heritiera littoralis and Xylocarpus granatum. Rates were measured on leaves at their natural angle of inclination at different levels in the canopy using a portable photosynthesis system. This research was undertaken to estimate net canopy carbon fixation and carbon accumulation as living biomass in mangrove forests using data on stand structure and rates of photosynthesis. This study is a component of a broader investigation of carbon fixation and storage by mangrove ecosystems.

Lineage

Maintenance and Update Frequency: notPlanned

Statement: Statement: A description of the allometric relationships used to estimate tree biomass from DBH is given in:Clough BF and Scott K (1989) Allometric relationships for estimating above-ground biomass in six mangrove species. Forest Ecology and Management 27: 117-127.Light flux was measured with a Delta-T quantum sensor (Delta-T Devices, Cambridge, England). The methods used for measuring light flux, simulating light profiles and estimating daily rates of whole canopy net carbon fixation are described in:Clough BF, Ong JE and Gong WK (1997) Estimating leaf area index and photosynthetic production in canopies of the mangrove Rhizophora apiculata. Marine Ecology Progress Series 159: 285-292. Rates of photosynthesis were measured using a Licor LI-6200 or LI-6400 portable photosynthesis system (Li-Cor Inc, Lincoln, Nebraska, USA).The relationship between above-ground and below-ground biomass in stands of Rhizophora apiculata in Malaysia is described in:Gong WK and Ong JE (1990) Plant biomass and nutrient flux in a managed mangrove forest in Malaysia. Estuarine, Coastal and Shelf Science 31: 516-530.Ong JE, Gong WK and Clough BF (1995) Structure and productivity of a 20-year-old stand of Rhizophora apiculata Bl. mangrove forest. Journal of Biogeography 22: 417-424.

Notes

Credit
Clough, Barry F, Dr (Principal Investigator)