Responses to nitrogen, phosphorus, potassium and sodium chloride by three mangrove species in pot culture

An understanding of nutritional requirements is important for both management and restoration of mangrove areas. In this study, the effects of nutrients on three dominant Australian mangrove species (Avicennia marina, Ceriops tagal and Rhizophora stylosa) were examined in a sand culture experiment. A factorial design with three levels each of N, P and K, and two levels of NaCl, was used. Nutrient levels were selected to reflect low, medium and high concentrations found in mangrove habitats. Branching pattern, leaf expansion rate and stem and leaf growth were monitored. Medium (0.714 mM) and high (2.14 mM) N levels markedly increased leaf number in all species, and height and branching in A. marina. Interaction effects, particularly between N, P and K, were apparent. Leaf expansion was also affected by N, P and K and their interaction with salinity; however, the pattern of response differed between species. The response of these species to added nutrients reflects their ecological niches in the field, and the likely effects of high-nutrient environments. This information can assist in management decisions such as the selection of species to use in wastewater treatment, or the use of certain fertilizers to enhance growth during revegetation.