Nitrogen dynamics in small watersheds in the Atlantic Forest and Cerrado in Northeastern Brazil

Abstract

The aim of this study was to determine concentrations of nitrogen (N) in two biomes, Atlantic Forest (AF) and Cerrado (CR), at the interface between terrestrial and aquatic ecosystems. This involved evaluating N in vegetation (litterfall), soil and water in small watersheds in environmental protection areas in northeastern Brazil. Soil chemical and physical analyzes were performed and mineralization and nitrification rates were determined. The forms of organic, inorganic and particulate nitrogen in water were determined by spectrophotometry. Two collections were carried out, one in the dry season (October and November 2019) and another in the rainy season (February and March 2020), in two environmental preservation areas, Estação Veracel Private Natural Heritage Reserve - (Atlantic Forest) and Chapada Diamantina National Park (Cerrado), with five small watersheds sampled in each biome. The N concentration in litterfall was similar in both biomes, with averages of 0.69%. In relation to soil and water, N concentrations were higher in AF compared to CR, with concentrations of 0.95 ± 0.40 and 0.59 ± 0.14 µg.Ng-1 of nitrate in the soils of AF and CR, respectively, and 3.53 ± 2.51 µM of nitrate in water in AF and 0.76 ± 0.78 µM in CR.