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Decomposition of soil organic matter

experimental and modelling studies of the importance of temperature and quality

Wetterstedt, Martin (2010). Decomposition of soil organic matter. Diss. (sammanfattning/summary) Uppsala : Sveriges lantbruksuniv., Acta Universitatis Agriculturae Sueciae, 1652-6880 ; 2010:21
ISBN 978-91-576-7498-2
[Doctoral thesis]

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Official URL: http://www2.ekol.slu.se/Personliga_filer/Wetterste...


The climate is changing and with it the capacity of soils to store carbon in all likelihood, since there is strong evidence that decomposition increases with increasing temperature. The soil contains about twice as much carbon as the atmosphere, so decreasing soil carbon will increase atmospheric CO₂ concentrations proportionally more, further contributing to temperature increase. Different types of soil carbon may respond differently to climate change. A central theory in explaining temperature sensitivity is the activation energy concept sensu Arrhenius. Applied to soil organic matter (SOM) it suggests that low quality SOM will respond more strongly to increased temperature than high quality SOM. Much of the carbon in soil is old and believed to be of low quality. This thesis examines the effects of temperature and SOM quality, separately and in combination. A model of decomposition as three processes in series resulted in unexpected temperature sensitivity, which may explain why the temperature sensitivity is so variable in the literature. A subsequent incubation experiment with different types of organic matter subjected to combinations of different initial and final temperatures showed that the temperature sensitivity increased with time, in agreement with existing theory. In contrast, the effects of past temperatures on present respiration were different than expected. When the decomposition experiment was modelled using the Q-model, decomposer efficiency decreased with temperature, greatly affecting the AOM quality decrease and indirectly affecting temperature sensitivity. Other results presented in the thesis showed that high quality SOM can be stored for hundreds of years and still be made available to decomposers simply by subjecting the soil to drying/wetting cycles. The results presented in this thesis have theoretical and experimental implications and indicate that quality might be less important than previously believed in terms of SOM susceptibility to increasing temperatures. The other processes involved need further attention.

Authors/Creators:Wetterstedt, Martin
Title:Decomposition of soil organic matter
Subtitle:experimental and modelling studies of the importance of temperature and quality
Series Name/Journal:Acta Universitatis Agriculturae Sueciae
Year of publishing :2010
Number of Pages:36
ALLI. Ågren GI, Wetterstedt JÅM. 2007. What determines the temperature response of soil organic matter decomposition? Soil Biology & Biochemistry 39:1794-1798. II. Wetterstedt JÅM, Persson T, Ågren GI. 2009. Temperature sensitivity and substrate quality in soil organic matter decomposition – results of an incubation study with three substrates. Global Change Biology (in press). III. Wetterstedt JÅM, Ågren GI. Quality or decomposer efficiency – which is most important for the temperature response of litter decomposition? A model analysis using the GLUE methodology (manuscript). IV. Schimel JP, Wetterstedt JÅM, Holden PA, Trumbore SE. Drying/rewetting cycles mobilize old C from deep soils from a California annual grassland (manuscript).
Place of Publication:Uppsala
ISBN for printed version:978-91-576-7498-2
Publication Type:Doctoral thesis
Full Text Status:Public
Agrovoc terms:soil, soil organic matter, plant litter, degradation, carbon, quality, temperature, in vitro experimentation, models
Keywords:quality, temperature-quality hypothesis, Q-model, decomposition, SOM, GLUE, Q10, temperature response, Arrhenius, Michaelis-Menten
Permanent URL:
ID Code:2244
Department:(NL, NJ) > Dept. of Ecology
(S) > Dept. of Ecology
Deposited By: Martin Wetterstedt
Deposited On:04 Mar 2010 00:00
Metadata Last Modified:02 Dec 2014 10:17

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