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| Titel |
A spatially explicit multi-isotope approach to map influence regions of plant-plant interactions after exotic plant invasion |
| VerfasserIn |
Christine Hellmann, Jens Oldeland, Christiane Werner |
| Konferenz |
EGU General Assembly 2015
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 17 (2015) |
| Datensatznummer |
250107442
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| Publikation (Nr.) |
 EGU/EGU2015-7145.pdf |
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| Zusammenfassung |
| Exotic plant invasions impose profound alterations to native ecosystems, including changes
of water, carbon and nutrient cycles. However, explicitly quantifying these impacts
remains a challenge. Stable isotopes, by providing natural tracers of biogeochemical
processes, can help to identify and measure such alterations in space and time. Recently,
δ15N isoscapes, i.e. spatially continuous representations of isotopic values, derived
from native plant foliage, enabled to accurately trace nitrogen introduced by the
N2-fixing invasive Acacia longifolia into a native Portuguese dune system. It could
be shown that the area of the system which was altered by the invasive species
exceeded the area which was covered by the invader by far. But still, definition of clear
regions of influence is to some extent ambiguous. Here, we present an approach using
multiple isoscapes derived from measured foliar δ13C and δ15N values of a native,
non-fixing species, Corema album. By clustering isotopic information, we obtained an
objective classification of the study area. Properties and spatial position of clusters
could be interpreted to distinguish areas that were or were not influenced by A.
longifolia. Spatial clusters at locations where A. longifolia was present had δ15N
values that were enriched, i.e.Âclose to the atmospheric signal of 0 o compared to
the depleted values of the uninvaded system (ca. -11 o). Furthermore, C. album
individuals in these clusters were characterized by higher foliar N content and enriched
δ13C. These results indicate that the N2-fixing A. longifolia added nitrogen to the
system which originated from the atmosphere and was used by the native C. album,
inducing functional changes, i.e.Âan increase in WUE. Additionally, clusters were
identified that were presumably determined by inherent properties of the native
system.
Thus, combining isotope ecology with geostatistical methods is a promising approach for
mapping regions of influence in multi-isotope isoscapes which may be relevant not only to
detect ecological boundaries within the context of exotic plant invasion but for
plant-plant-interactions and small-scale variability of biotic and abiotic conditions in general. |
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