Variations in mangrove forest productivity in northern Australia and Papua New Guinea

A survey method previously developed for estimating potential net primary production (PN) of mangrove forests was applied at 19 widely separated sites in tropical northern Australia and six sites in the Gulf of Papua. These estimates are compared with previous results for mangrove forests at Hinchinbrook Island, north Queensland. Surveys of soil properties in these areas indicate that low availability of soil phosphorus is a major contributing factor to the consistently in PN estimates of Cape York and North-western Australian forests (range in PN=11–26; mean PN= 19kg C ha−1 day−1) compared with the Hinchin-brook Island and Gulf of Papua forests (range in PN=3–38; mean PN=26 kg C ha−1 day−1). The regional variation and possible effects of other soil properties, such as redox potential and salinity, are discussed briefly. It is suggested that the generally low salinities and moderate soil redox status may partially offset the effects of low soil P in the Cape York region.