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Glob Chang Biol. 2017 Apr;23(4):1725-1734. doi: 10.1111/gcb.13502. Epub 2016 Oct 8.

Litter decay controlled by temperature, not soil properties, affecting future soil carbon.

Author information

1
Agriculture & Agri-Food Canada (AAFC) Research & Development Centre, Central Experimental Farm, Ottawa, ON, K1A 0C6, Canada.
2
AAFC Research & Development Centre, Lethbridge, AB, T1J 4B1, Canada.
3
AAFC Research & Development Centre, Saskatoon, SK, S7H 5A8, Canada.
4
AAFC Research & Development Centre, Fredericton, NB, E3B 4Z7, Canada.
5
AAFC Research & Development Centre, Quebec, QC, G1V 2J3, Canada.
6
AAFC Research & Development Centre, London, ON, N5V 4T3, Canada.
7
AAFC Research & Development Centre, Harrow, ON, N0R 1G0, Canada.
8
AAFC Research & Development Centre, Morden, MB, R6M 1Y5, Canada.
9
AAFC Research & Development Centre, Indian Head, SK, S0G 2K0, Canada.
10
AAFC Research & Development Centre, Swift Current, SK, S9H 3X2, Canada.
11
Department of Renewable Resources, University of Alberta, Edmonton, AB, T6G 2H1, Canada.

Abstract

Widespread global changes, including rising atmospheric CO2 concentrations, climate warming and loss of biodiversity, are predicted for this century; all of these will affect terrestrial ecosystem processes like plant litter decomposition. Conversely, increased plant litter decomposition can have potential carbon-cycle feedbacks on atmospheric CO2 levels, climate warming and biodiversity. But predicting litter decomposition is difficult because of many interacting factors related to the chemical, physical and biological properties of soil, as well as to climate and agricultural management practices. We applied 13 C-labelled plant litter to soil at ten sites spanning a 3500-km transect across the agricultural regions of Canada and measured its decomposition over five years. Despite large differences in soil type and climatic conditions, we found that the kinetics of litter decomposition were similar once the effect of temperature had been removed, indicating no measurable effect of soil properties. A two-pool exponential decay model expressing undecomposed carbon simply as a function of thermal time accurately described kinetics of decomposition. (R2  = 0.94; RMSE = 0.0508). Soil properties such as texture, cation exchange capacity, pH and moisture, although very different among sites, had minimal discernible influence on decomposition kinetics. Using this kinetic model under different climate change scenarios, we projected that the time required to decompose 50% of the litter (i.e. the labile fractions) would be reduced by 1-4 months, whereas time required to decompose 90% of the litter (including recalcitrant fractions) would be reduced by 1 year in cooler sites to as much as 2 years in warmer sites. These findings confirm quantitatively the sensitivity of litter decomposition to temperature increases and demonstrate how climate change may constrain future soil carbon storage, an effect apparently not influenced by soil properties.

KEYWORDS:

agriculture; carbon cycling; climate change; litter decomposition; temperature

PMID:
27633488
DOI:
10.1111/gcb.13502
[Indexed for MEDLINE]

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