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| Titel |
Belowground carbon allocation patterns in a dry Mediterranean ecosystem: a comparison of two models. |
| VerfasserIn |
Maria Almagro, Jorge López, Carolina Boix-Fayos, Juan Albadalejo, Maria Martínez-Mena |
| Konferenz |
EGU General Assembly 2010
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 12 (2010) |
| Datensatznummer |
250040259
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| Zusammenfassung |
| Total belowground C allocation (TBCA) represents a large fraction of gross primary
production; it can exceed aboveground net primary production, and provides the primary
source of detrital C to mineral soil. Here, we measure soil respiration, water erosion, litterfall
and estimated annual changes in C stored in mineral soil, litter and roots, in three
representative land uses in a Mediterranean ecosystem (late-successional forest, abandoned
agricultural field, rain-fed olive grove), and use two C balance approaches (steady-state
and non-steady-state) to estimate TBCA. Both TBCA approaches are compared to
assess how different C fluxes (outputs and inputs) affect our estimates of TBCA
within each land use. In addition, annual net ecosystem productivity is determined
and C allocation patterns are examined for each land use. We hypothesized that
changes in C stored in mineral soil, litter and roots will be minor compared to soil
respiration, but will still have a significant effect on the estimates of TBCA. Annual net
ecosystem productivity was 648, 541 and 324 g C m-2 yr-1 for forest, abandoned
field and olive grove, respectively. Across land uses, more than 60 % of the C was
allocated belowground. Soil respiration (FS) was the largest component in the TBCA
approaches across all land uses. Annual C losses through water erosion were negligible
compared to FS (less than 1%) and had little effect on the estimates of TBCA. Annual
changes in C stored in the soil, litter layer and roots were low compared to FS
(16, 24 and 10 % for forest, abandoned field and olive grove, respectively), but
had a significant effect on the estimates of TBCA. In our sites, an assumption that
Î[CS + CR + CL]/Ît= 0 will give biased estimates of TBCA, particularly in the
abandoned agricultural field, where soil C storage may be increasing more rapidly.
Therefore, the steady-state model is unsuited to these Mediterranean ecosystems
and the full model is recommended. The results from this study provide useful
information for those studies analyzing global patterns in belowground C flux and
partitioning in ecosystems, in which water-limited ecosystems are under-represented. |
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