 |
| Titel |
Aggregate and soil organic carbon dynamics in South Chilean Andisols |
| VerfasserIn |
D. Huygens, P. Boeckx, O. Cleemput, C. Oyarzún, R. Godoy |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 2, no. 2 ; Nr. 2, no. 2 (2005-06-24), S.159-174 |
| Datensatznummer |
250000490
|
| Publikation (Nr.) |
 copernicus.org/bg-2-159-2005.pdf |
|
|
|
|
|
| Zusammenfassung |
| Extreme sensitivity of soil organic carbon (SOC) to climate and land use
change warrants further research in different terrestrial ecosystems. The
aim of this study was to investigate the link between aggregate and SOC
dynamics in a chronosequence of three different land uses of a south Chilean
Andisol: a second growth Nothofagus obliqua forest (SGFOR), a grassland (GRASS) and a Pinus radiata
plantation (PINUS). Total carbon content of the 0-10cm soil layer was higher
for GRASS (6.7 kg C m-2) than for PINUS (4.3 kg C m-2, while TC
content of SGFOR (5.8 kg C m-2) was not significantly different from
either one. High extractable oxalate and pyrophosphate Al concentrations
(varying from 20.3-24.4 g kg-1, and 3.9-11.1 g kg-1, respectively)
were found in all sites. In this study, SOC and aggregate dynamics were
studied using size and density fractionation experiments of the SOC, δ13C
and total carbon analysis of the different SOC fractions, and C
mineralization experiments. The results showed that electrostatic sorption
between and among amorphous Al components and clay minerals is mainly
responsible for the formation of metal-humus-clay complexes and the
stabilization of soil aggregates. The process of ligand exchange between SOC
and Al would be of minor importance resulting in the absence of aggregate
hierarchy in this soil type. Whole soil C mineralization rate constants were
highest for SGFOR and PINUS, followed by GRASS (respectively 0.495, 0.266
and 0.196 g CO2-Cm-2d-1 for the top soil layer). In
contrast, incubation experiments of isolated macro organic matter fractions
gave opposite results, showing that the recalcitrance of the SOC decreased
in another order: PINUS>SGFOR>GRASS. We deduced that electrostatic
sorption processes and physical protection of SOC in soil aggregates were
the main processes determining SOC stabilization. As a result, high
aggregate carbon concentrations, varying from 148 till 48 g kg-1, were
encountered for all land use sites. Al availability and electrostatic
charges are dependent on pH, resulting in an important influence of soil pH
on aggregate stability. Recalcitrance of the SOC did not appear to largely
affect SOC stabilization. Statistical correlations between extractable
amorphous Al contents, aggregate stability and C mineralization rate
constants were encountered, supporting this hypothesis. Land use changes
affected SOC dynamics and aggregate stability by modifying soil pH (and thus
electrostatic charges and available Al content), root SOC input and
management practices (such as ploughing and accompanying drying of the
soil). |
| |
|
| Teil von |
|
|
|
|
|
|
|
|