Dynamics of phosphorus and sulphur in a mangrove forest in Braganca, North Brazil

Three forests along a 600-m transect within a tropical mangrove in North Brazil were studied in a series of 1-m cores at rainy season to determine the chemical and physicochemical change relative to hydrology and species-specific effects. In North Brazil, macrotides are an important factor associated with the spatial variation of the mangrove species. The results indicated an inundation two times higher at low plain (LP) colonized by a monospecific forests Rhizophora mangle than in high plain (HP) at Avicennia germinans forests. The flooding gradient result in a slightly acidic to basic pH (6.3-7.5) and lower redox potential (Eh) (0-100 mV) levels in LP sediments compared to HP (200 mV). Phosphorus (P), sulphur and iron dynamics are closely coupled to the activity of mangroves trees and sulphate-reducing bacteria, suggesting that a combined effect of flooding with the P dynamics and the plant-sediment-microbial feedback contributes to the zonation of the investigated mangroves.