Sayer, E.J. and Lopez-Sangil, L. and Crawford, J.A. and Bréchet, L.M. and Birkett, A.J. and Baxendale, C. and Castro, B. and Rodtassana, C. and Garnett, M.H. and Weiss, L. and Schmidt, M.W.I. (2019) Tropical forest soil carbon stocks do not increase despite 15 years of doubled litter inputs. Scientific Reports, 9 (1). ISSN 2045-2322
Full text not available from this repository.Abstract
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.