The production, allocation and cycling of carbon in a forest on fertile terra preta soil in eastern Amazonia compared with a forest on adjacent infertile soil

Abstract

Background: Terra preta do indio or ‘dark earth’ soils formed as a result of a long-term addition of organic matter by indigenous peoples in Amazonia.

Aims: Here we report on the first study of productivity, allocation and carbon cycling from a terra preta plot in eastern Amazonia (Caxiuanã, Pará, Brazil), and contrast its dynamics with a nearby plot on infertile soil (ferralsols).

Methods: We determined total net primary production (NPP) for fine roots, wood, and canopy and total autotrophic respiration (rhizosphere, wood, and canopy respiration) from two 1-ha plots on contrasting soils.

Results: Both gross primary productivity (GPP) (35.68 ± 3.65 vs. 32.08 ± 3.46 Mg C ha⁻¹ year⁻¹) and carbon use efficiency (CUE) (0.44 ± 0.06 vs. 0.42 ± 0.05) were slightly higher at the terra preta plot. Total NPP (15.77 ± 1.13 Mg C ha⁻¹ year⁻¹ vs. 13.57 ± 0.60 Mg C ha⁻¹ year⁻¹) and rates of fine root production (6.41 ± 1.08 vs. 3.68 ± 0.52 Mg C ha⁻¹ year⁻¹) were also greater at the terra preta plot vs. the tower plot.

Conclusions: Forests on terra preta soil fix slightly more carbon and allocate slightly more of that carbon towards growth than forests on the infertile plot, which leads to greater total NPP, which was disproportionately allocated to fine roots. However, since increased fine root NPP was partially offset by increased heterotrophic soil respiration, the increased root growth was unlikely to greatly enhance soil carbon stocks in terra preta soils.

Keywords:

• anthrosol
• carbon use efficiency (CUE)
• gross primary productivity (GPP)
• net primary production (NPP)
• terra preta
• tropical forests

Acknowledgements

This work is a product of the RAINFOR consortium and a component site of the GEM (Global Ecosystems Monitoring) network. It was funded by a grant from the Gordon and Betty Moore Foundation to the Amazon Forest Inventory Network (RAINFOR), and a grant to YM from the UK Natural Environment Research Council (Grants NE/D014174/1). YM is supported by the Jackson Foundation. We thank the Museu Paraense Emilio Goeldi and their Ferreira Penna Scientific Field Station at Caxiuanã for invaluable field support. We dedicate this paper to the memory of our co-author Samuel Almeida, who was so instrumental and enthusiastic in establishing this study and selecting the study plot.

Notes

^†Deceased