a matter of efficiency?
Bölscher, Tobias
(2016).
Decomposition of soil organic matter under a changing climate.
Diss. (sammanfattning/summary)
Uppsala :
Sveriges lantbruksuniv.,
Acta Universitatis Agriculturae Sueciae, 1652-6880
; 2016:85
ISBN 978-91-576-8672-5
eISBN 978-91-576-8673-2
[Doctoral thesis]
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Abstract
Soil organic matter is the largest carbon (C) pool in the terrestrial C cycle, and soil CO₂ emissions surpass anthropogenic emissions from fossil fuel combustion by a factor of nine. Therefore, mechanisms controlling C stabilisation in soils and its feedback to climate change are widely debated. During decomposition, microbial substrate-use efficiency is an important property because it determines the allocation of substrate C to biosynthesis and respiratory losses. High efficiency values indicate that C primarily remains in soils while low efficiency implies that C is primarily lost into the atmosphere. Despite empirical evidence that efficiency is temperature sensitive, traditional Earth system models treat this property as a constant.
The aim of this thesis was to improve our mechanistic understanding of drivers regulating substrate-use efficiency with special consideration to climate change. It investigated the impacts of (i) temperature, (ii) microbial community composition and (iii) substrate quality on substrate-use efficiency. Within the thesis, a microbial energetics approach was applied and further developed using isothermal calorimetry. Further, the thesis compared common approaches for measuring microbial substrate-use efficiency, and the implications of the resultant empirical data for projected C stocks were tested using a modelling approach.
Substrate-use efficiency was generally temperature sensitive and decreased with increasing temperature. The observed temperature responses were non-linear and varied across land use management systems. The changes in substrate-use efficiency with temperature were driven rather by changes in microbial physiology than by shifts in active microbial communities. Nevertheless, fungi and Gram-negative bacteria tended towards relatively higher efficiencies. Efficiencies varied among utilised substrates, but substrate quality per se was a poor proxy for efficiency. Projected losses from soil C stocks varied across land use management systems and were up to 39 % and 15 % for grassland and forest systems, respectively. Results from the modelling approach confirmed that substrate-use efficiency is one of the factors to which soil C stocks react most sensitively. Findings from this thesis emphasise the importance of furthering our understanding of substrate-use efficiency for reliable climate projections.
Authors/Creators: | Bölscher, Tobias | ||||||||||
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Title: | Decomposition of soil organic matter under a changing climate | ||||||||||
Subtitle: | a matter of efficiency? | ||||||||||
Series Name/Journal: | Acta Universitatis Agriculturae Sueciae | ||||||||||
Year of publishing : | 29 September 2016 | ||||||||||
Number: | 2016:85 | ||||||||||
Number of Pages: | 53 | ||||||||||
Papers/manuscripts: |
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Place of Publication: | Uppsala | ||||||||||
Publisher: | Department of Chemistry and Biotechnology, Swedish University of Agricultural Sciences | ||||||||||
ISBN for printed version: | 978-91-576-8672-5 | ||||||||||
ISBN for electronic version: | 978-91-576-8673-2 | ||||||||||
ISSN: | 1652-6880 | ||||||||||
Language: | English | ||||||||||
Publication Type: | Doctoral thesis | ||||||||||
Full Text Status: | Public | ||||||||||
Agris subject categories.: | P Natural resources > P33 Soil chemistry and physics | ||||||||||
Subjects: | (A) Swedish standard research categories 2011 > 1 Natural sciences > 105 Earth and Related Environmental Sciences > Climate Research (A) Swedish standard research categories 2011 > 4 Agricultural Sciences > 401 Agricultural, Forestry and Fisheries > Soil Science | ||||||||||
Agrovoc terms: | soil organic matter, degradation, efficiency, climate change, temperature, land use, soil microorganisms, calorimetry, carbon, models | ||||||||||
Keywords: | soil organic matter, substrate-use efficiency, temperature, land use, microbial community, substrate quality, isothermal calorimetry, carbon modelling | ||||||||||
URN:NBN: | urn:nbn:se:slu:epsilon-e-3678 | ||||||||||
Permanent URL: | http://urn.kb.se/resolve?urn=urn:nbn:se:slu:epsilon-e-3678 | ||||||||||
ID Code: | 13673 | ||||||||||
Faculty: | NJ - Fakulteten för naturresurser och jordbruksvetenskap | ||||||||||
Department: | (NL, NJ) > Department of Chemistry and Biotechnology (140101-161231) | ||||||||||
External funders: | FORMAS | ||||||||||
Deposited By: | Tobias Bölscher | ||||||||||
Deposited On: | 21 Sep 2016 11:16 | ||||||||||
Metadata Last Modified: | 10 Sep 2020 13:41 |
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