Tropical forest soil carbon stocks do not increase despite 15 years of doubled litter inputs

Sayer, E. et al. (2019) Tropical forest soil carbon stocks do not increase despite 15 years of doubled litter inputs. Scientific Reports, 9, 18030. (doi: 10.1038/s41598-019-54487-2) (PMID:31792257) (PMCID:PMC6888873)

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Soil organic carbon (SOC) dynamics represent a persisting uncertainty in our understanding of the global carbon cycle. SOC storage is strongly linked to plant inputs via the formation of soil organic matter, but soil geochemistry also plays a critical role. In tropical soils with rapid SOC turnover, the association of organic matter with soil minerals is particularly important for stabilising SOC but projected increases in tropical forest productivity could trigger feedbacks that stimulate the release of stored SOC. Here, we demonstrate limited additional SOC storage after 13–15 years of experimentally doubled aboveground litter inputs in a lowland tropical forest. We combined biological, physical, and chemical methods to characterise SOC along a gradient of bioavailability. After 13 years of monthly litter addition treatments, most of the additional SOC was readily bioavailable and we observed no increase in mineral-associated SOC. Importantly, SOC with weak association to soil minerals declined in response to long-term litter addition, suggesting that increased plant inputs could modify the formation of organo-mineral complexes in tropical soils. Hence, we demonstrate the limited capacity of tropical soils to sequester additional C inputs and provide insights into potential underlying mechanisms.

Item Type:Articles
Additional Information:This work was funded by a European Research Council Starting Grant, awarded to E.J.S. under the European Union’s Seventh Framework Programme (FP/2007–2013), ERC Grant Agreement No. 307888 and supported by the NERC Radiocarbon Facility NRCF010001 (allocation number 2042.1016).
Glasgow Author(s) Enlighten ID:Garnett, Dr Mark
Authors: Sayer, E., Lopez-Sangil, L., Crawford, J., Bréchet, L., Birkett, A., Baxendale, C., Castro, B., Rodtassana, C., Garnett, M., Weiss, L., and Schmidt, M.
College/School:College of Science and Engineering > Scottish Universities Environmental Research Centre
Journal Name:Scientific Reports
Publisher:Nature Publishing Group
ISSN (Online):2045-2322
Published Online:02 December 2019
Copyright Holders:Copyright © The Authors 2019
First Published:First published in Scientific Reports 9:18030
Publisher Policy:Reproduced under a Creative Commons license

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