 |
| Titel |
The influence of woody thickening on SOM dynamics along a precipitation gradient in West Africa |
| VerfasserIn |
Gustavo Saiz, Michael Bird, Christopher Wurster, Philippa Ascough, Elmar Veenendaal, Klaus Butterbach-Bahl, Franziska Schrodt, Tomas Domingues, Ted Feldpausch, Victor Braojos, Jonathan Lloyd |
| Konferenz |
EGU General Assembly 2014
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250100211
|
| Publikation (Nr.) |
 EGU/EGU2014-16105.pdf |
|
|
|
|
|
| Zusammenfassung |
| We made use of the carbon isotopic composition of soil organic matter (SOM) in bulk and
fractionated samples to assess the influence of C3/C4 vegetation on SOM dynamics in
semi-natural tropical ecosystems sampled along a precipitation gradient in West Africa. The
non-linear nature of the relationship between δ13C and SOC content observed across the
latitudinal gradient strongly suggests that in addition to the inherent differences in the
input rates and turnover times of tree and grass-derived carbon, the broad range of
edaphic characteristics may have a major effect in both the physical protection of
particulate organic carbon and the chemical stabilization of 13C enriched microbial
metabolites.
The stable carbon isotopic composition of SOM with depth indicated that there was a
larger proliferation in woody vegetation with increasing precipitation, with such trend being
also heavily dependent on the characteristics of the soils. An unbiased assessment of the
potential impact of tropical vegetation thickening on SOM dynamics is characteristically
difficult given the confounding effects posed by the interaction of varying climatic and
edaphic factors. Therefore, in order to minimize the impact of those factors, we selected two
neighboring transitional ecosystems (a closed savanna woodland and a semideciduous dry
forest) occurring in soils of comparable characteristics. Both sites showed varying
degrees of δ13C enrichment with depth in bulk and fractionated SOM. Moreover,
radiocarbon analyses of sand-size aggregates (>53 μm HF) yielded relatively short
MRT, which shows highly dynamic SOM processes even in fairly deep locations.
Interestingly, the most stable SOM fraction associated to silt and clay ( |
|
|
|
|
|
|