Seasonal dynamics of litterfall nutrients in a native Brazil nut stand in the Tapajós National Forest, Eastern Amazon

Abstract

This study quantified carbon (C), nitrogen (N), and sulfur (S) concentrations in the litterfall of a native Brazil nut (Bertholletia excelsa) stand in the Tapajós National Forest, Belterra (Pará, Brazil), across dry and wet seasons. Monthly collections were conducted from August 2015 to July 2016 within a permanent plot of the MapCast Project, using 12 circular litter traps (0.25 m² each) systematically distributed in the forest. Litterfall was separated into leaves, flowers and fruits, wood, and miscellaneous fractions. After drying and sorting, samples were analyzed for C, N, and S contents using an elemental analyzer (CHNS/O). Seasonal patterns in elemental composition were observed: higher N and S concentrations occurred during the wet season, particularly in the miscellaneous fraction, whereas C was more abundant in the dry season, especially in leaves. Nevertheless, differences between seasons were not statistically significant (t-test, p ≤ 0.05). Significant correlations between nutrient contents and climatic variables (precipitation and temperature) were detected, emphasizing the responsiveness of litterfall to environmental variation. Overall, the results demonstrate that litterfall acts as a key reservoir and pathway for nutrient transfer in Brazil nut-dominated Amazonian forests, contributing to nutrient cycling and sustaining soil fertility. The persistence of litter on the soil surface plays an essential role in conserving edaphic fertility and supporting ecological stability. These findings provide valuable insights for forest management and conservation practices, while also advancing the understanding of biogeochemical processes that regulate the functioning and resilience of tropical ecosystems.

Keywords: cycling, fertility, forest.