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| Titel |
Modeling the spatial impact of an invasive N2-fixing Acacia by means of isotopic and optical measurements |
| VerfasserIn |
Christine Hellmann, André Große-Stoltenberg, Cristina Máguas, Jens Oldeland, Katherine G. Rascher, Jan Thiele, Christiane Werner |
| 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 |
250097240
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| Publikation (Nr.) |
 EGU/EGU2014-12799.pdf |
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| Zusammenfassung |
| Invasions by exotic plant species are known to seriously alter biogeochemical cycles and
ecosystem functioning of the systems they invade, with nitrogen fixing species
being among the most problematic invaders. However, explicitly quantifying such
alterations remains challenging, as methods are lacking to capture the spatial scale of
impact.
Here, we present a spatially explicit approach allowing to quantify the impact of an N2-fixing
invasive species, Acacia longifolia, on a native Portuguese dune system by means of stable
isotope analyses. 15N isotopic signatures (δ15N) differed strongly between the native system
(δ15N c. -10 o) and atmospherically derived N in A. longifolia (δ15N c. 0 o).
Thus, N sources for a native, non-fixing plant, Corema album, could be readily
distinguished. Using georeferenced δ15N values of C. album, we could accurately map
N introduced by A. longifolia on a spatial scale. N input exceeded the canopy of
the N2 fixer by far and reached up to 8 m into the uninvaded vegetation. The area
altered by invasion was c. 3.5 fold larger than the area covered by the invader’s
canopy.
Our results highlight that spatially explicit measurements of sensitive ecological tracers like
stable isotopic signatures, i.e.isoscapes, provide a valuable means to quantify alterations of
biogeochemical cycles within plant communities.
Moreover, linking stable isotopes with optical measurements and remote sensing can
be a powerful tool to upscale such information from leaf- to larger spatial scales.
Here we show that foliar δ15N signatures can be accurately modeled using leaf
reflectance spectra. This approach opens promising future perspectives in ecosystem
monitoring based on the potential use of hyperspectral aerial and satellite imagery. |
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