Abstract

The Amazon rainforest is considered the most important ecosystem in the world for the global carbon balance due to its high carbon storage in soil and in the vegetation. Unfortunately, there are few studies about organic fraction of its soils. Thus, the present research aimed to quantify the soil organic carbon content (OC) and to analyze its spatial distribution using 701 soil samples from minimally anthropic areas compiled from previous studies. Descriptive statistics, Pearson correlation and spatial variability analyses of OC and other physical and chemical soil data were performed. The high variability of OC between soil groups were attributed to the preservation and protection of carbon by oxides, reduction process and organic-rich parent material. OC was strongly positively correlated with total nitrogen (N) content, C:N ratio and cation exchange capacity at pH 7.0. The maps produced showing the spatial distribution of CO and that based on C:N ratio would be support for the creation of priority areas in the conservation of ecosystem.

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