Long-term sensitivity of soil carbon turnover to warming

W. Knorr*, I. C. Prentice, J. I. House, E. A. Holland

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

854 Citations (Scopus)

Abstract

The sensitivity of soil carbon to warming is a major uncertainty in projections of carbon dioxide concentration and climate1. Experimental studies overwhelmingly indicate increased soil organic carbon (SOC) decomposition2-8 at higher temperatures, resulting in increased carbon dioxide emissions from soils. However, recent findings have been cited as evidence against increased soil carbon emissions in a warmer world 9,10. In soil warming experiments, the initially increased carbon dioxide efflux returns to pre-warming rates within one to three years 10-14, and apparent carbon pool turnover times are insensitive to temperature15. It has already been suggested that the apparent lack of temperature dependence could be an artefact due to neglecting the extreme heterogeneity of soil carbon16, but no explicit model has yet been presented that can reconcile all the above findings. Here we present a simple three-pool model that partitions SOC into components with different intrinsic turn-over rates. Using this model, we show that the results of all the soil-warming experiments are compatible with long-term temperature sensitivity of SOC turnover: they can be explained by rapid depletion of labile SOC combined with the negligible response of non-labile SOC on experimental timescales. Furthermore, we present evidence that non-labile SOC is more sensitive to temperature than labile SOC, implying that the long-term positive feedback of soil decomposition in a warming world may be even stronger than predicted by global models1,17-20.

Original languageEnglish
Pages (from-to)298-301
Number of pages4
JournalNature
Volume433
Issue number7023
DOIs
Publication statusPublished - 20 Jan 2005
Externally publishedYes

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