Soil phosphorus fractions and their relation to leaf litterfall in a central Amazonian terra firme rainforest

ABSTRACT Phosphorus (P) cycling is an important yet poorly studied aspect of the macronutrient balance in tropical rainforest ecosystems. As soil P occurs different organic and inorganic forms (fractions) with varying degrees lability, we hypothesized that these fractions will vary between types, temporally within types. Additionally, a direct influence leaf litterfall input on total fractions. We collected litter samples from three types central Amazonian lowland Brazil over five months, used modified Hedleys fractionation method to determine six fractions, also total, labile residual P. Leaf concentrations were determined colorimetrically. Soil varied across but type month interactions mostly non-significant. Some (Pi-NaOH) peaked while (Po-NaOH) fell vice versa. production around two months following wettest month. was significant predictor Po-NaHCO3, bioavailable fraction. Future studies terrestrial ecosystems should examine roles played by individual as they cycle asynchronistically differently