Aboveground fine litterfall and decomposition are critical processes for transferring nutrients from forest biomass to soils, and the conversion of Brazilian terra-firme forest to tree plantations with varied litterfall characteristics has altered soil nitrogen (N) dynamics and stores at the Curuá-Una Forest Reserve, Pará, Brazil. In this study, we investigated the relationship between soil N stores and aboveground litter inputs by measuring fine litterfall, litter N inputs, forest-floor mass and turnover, foliar N concentrations, and within-stand nitrogen-use efficiency (NUE) for one year under four plantations and adjacent undisturbed forest. The plantations consisted of replicated plots of Pinus caribaea var. hondurensis (36-year old), Carapa guianensis (36-year old), Euxylophora paraensis (23-year old), and a Leguminosae combination ( Parkia multijuga, Dinizia excelsa, and Dalbergia nigra, all 36-year old). Fine litterfall ranged from 8.0 ( Euxylophora paraensis) to 10.3 t ha −1 year −1 ( Pinus caribaea), forest-floor mass from 7.2 (forest) to 11.0 t ha −1 ( Pinus caribaea), total fine litterfall N inputs from 43 ( Pinus caribaea) to 134 kg ha −1 year −1 (legumes), and foliar N concentrations from 9 ( Pinus caribaea) to 18.8 mg g −1 (legumes). Relative to adjacent terra-firme forest, total N stores in surface mineral soils, forest-floor mass, and fine roots (live+dead) ranged from a net decrease of 25.6% under Pinus caribaea to a net increase of 14% under Euxylophora paraensis. The replacement of terra-firme forest with plantations of tree species with varied phenologies and resource requirements altered soil N stores, but these changes were not related to total fine litter N inputs, needle and foliar N concentrations, or within-stand nitrogen-use efficiency.