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| Titel |
Combined climatic and geochemical controls on stabilizing soil carbon along a large scale transect from the South American tropics to Antarctica |
| VerfasserIn |
Sebastian Doetterl, Pascal Boeckx, Johan Six, Erick Zagal Venegas |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250093892
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| Publikation (Nr.) |
 EGU/EGU2014-9065.pdf |
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| Zusammenfassung |
| The importance of climatic variables on biological processes that stabilize versus destabilize
soil organic carbon (C), has been long studied and recognized. Also, the importance of
geochemical factors controlling C stabilization, namely the composition of the reactive soil
phase, has been studied extensively and different physical and geochemical mechanisms of
soil C stabilization have been identified. However few studies have considered
the combined effect of these two critical controls (climate and geology) on soil C
stabilization.
We present the concept and the first results of a large scale project that aims to improve
our understanding of the linkage between climatic and geochemical controls on soil C
dynamics. For this, we study soils formed under grassland vegetation along a geo-climatic
transect in Chile, Brazil and the Antarctic Peninsula. We cover in our experiments all major
global climate zones under which grasses can thrive, including hot, temperate and cold humid
or arid climates, and in each zone we study soils developed from contrasting geochemical
substrate.
The focus of our study is to determine the physical and geochemical mechanisms which
play a role in stabilizing carbon in different soil fractions under these various climates, and to
determine the associated turnover times. On exemplary topsoil samples from our transect we
combine a series of physical and chemical soil fractionation experiments with a medium-term
incubation study using 13C and 15N labelled grass residues. In addition, we also determine
the age of the respired C during the incubation using 14C dating on soil C and CO2. This
combination of techniques helps trace microbial activity in certain parts of the soil
and analyze the reactivity and abundance of various C fractions and, hence, the
presence, effectiveness and interaction of different C stabilization mechanisms. |
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