Abstract for presentation at Biodiversity Extinction Crisis Conference - A Pacific Response

Little is known about the carbon cycles of forest ecosystems in Papua New Guinea, especially mangrove systems. Few studies have related carbon productivity with biomass production and litter fall. Due to the pressing issue of climate change, carbon productivity studies are critically important. Therefore, in 2005 I conducted a study in Central Province, Papua New Guinea, estimating carbon cycles of mangrove forests by measuring standing above-ground biomass and litter fall accumulation. At two sites (Barakau and Motupore Island), a total of 36 litter fall traps were placed along a 100 m transect and monitored monthly for seven months. Height and DBH of trees (≥ 10 cm) were measured along transects. Collected leaf-litters were sorted into species then dried and weighed. Total litter production at the two sites was 6.5 t ha ^-1yr^-1, while above ground biomass ranged from 1.44 to 4.41 t ha^-1(dry weight). Assuming 45–50 % of all dry weight is carbon, the mangrove forest in Central Province produces 2.93 - 3.25 t C ha^-1 yr^-1 of litter and sequesters 0.65 to 2.21 t C ha^-1 in terms of standing aboveground biomass. The two sites differed in standing aboveground biomass and litter fall production. Motupore Island produced 0.279 m³ m^-2month^-1 and 67.30 g m^-2month^-1 respectively, whereas Barakau produced 2.021 m³ m^-2month^-1 and 41.23 g m^-2month^-1 respectively. This result indicates that Motupore Island was more disturbed than Barakau, as disturbed forests release more carbon into the atmosphere and sequesters less, and therefore contribute more towards global warming. The amount of carbon released into atmosphere from disturbance to mangroves is unknown and needs to be researched. However, compared to other forest types mangrove forest appears to produce more carbon in terms of leaf litter fall, though more research is needed to confirm our finding, and steps taken to conserve mangrove forests.