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| Titel |
Mutually supportive use of stable isotope and gas chromatography techniques to understand ecohydrological interactions in dryland environments |
| VerfasserIn |
A. Puttock, R. E. Brazier, J. A. J. Dungait, R. Bol, E. R. Dixon, C. J. A. Macleod |
| Konferenz |
EGU General Assembly 2012
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 14 (2012) |
| Datensatznummer |
250060420
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| Zusammenfassung |
| Many drylands globally are experiencing extensive vegetation change. In the semi-arid
Southwestern United States, this change is characterised by the encroachment of woody
vegetation into environments previously dominated by grassland (Van Auken. 2009). The
transition from grass to woody vegetation results in a change in ecosystem structure and
function (Turnbull et al. 2008). Structural change is typically characterised by an increased
heterogeneity of soil and vegetation resources, associated with reduced vegetation coverage
and an increased vulnerability to soil erosion and the potential loss of key nutrients to
adjacent fluvial systems.
This project uses an ecohydrological approach, monitoring natural rainfall-runoff events
and resulting water and sediment fluxes over six bounded plots with different vegetation
coverage at the Sevilleta National Wildlife Refuge, New Mexico, USA. The experiment takes
advantage of a shift in the photosynthetic pathway of dominant vegetation from C3
piñon-juniper (Pinus edulis-Juniperus monosperma) mixed stand through a C4 pure-grass
(Bouteloua eriopoda) to C3 shrub (Larrea tridentate). This allows for the utilisation of
natural abundance tracing techniques, specifically stable 13C isotope and gas chromatography
lipid biomarker analyses.
Results collected during the 2010 and 2011 monsoon seasons will be presented, using
biogeochemical signatures, to trace and partition fluvial soil organic matter and carbon fluxes
during runoff generating rainfall events. Results show that biogeochemical signatures specific
to individual plant species can be used to define the provenance of carbon, quantifying
whether more Pinus edulis-Juniperus monosperma derived carbon is mobilised from the
upland plots, or whether more Larrea tridentata carbon is lost when compared to bouteloa
eripoda losses in the lowlands. Results also show that biogeochemical signatures vary with
event characteristics, raising the possibility of using these tracing techniques to further our
understanding of ecohydrological interactions and rainfall-runoff dynamics over these
dryland vegetation transitions.
Turnbull, L., J. Wainright, and R. E. Brazier. 2008. A conceptual framework for
understanding semi-arid land degradation: ecohydrological interactions across multiple-space
and time scales. Ecohydrology 1:23-34.
Van Auken, O. W. 2009. Causes and consequences of woody plant encroachment into
western North American grasslands. Journal of Environmental Management 90 2931-2942. |
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