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| Titel |
The impact of Ground Water lowering conditions in a Mediterranean coastal sand dune plant community: the responsiveness of different functional groups according to season and spatial heterogeneity |
| VerfasserIn |
Cristina Máguas, Katherine Rascher, Cristina Antunes, Margarida Ramos, Amélia Martins-Loução, Paulo Gaspar, Otília Correia, Christiane Werner |
| 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 |
250040477
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| Zusammenfassung |
| The relatively small number of studies on the responsiveness of Mediterranean sand dunes
vegetation to the ground water (GW) table variability, makes this study one of the few
attempts to identify the degree of usage and dependence of groundwater, as well as the
understanding of basic drivers for plant functional response. One way to determine the
presence of ground water ecosystems more rigorously is by using stable isotope composition
of water in the soil, groundwater and xylem of vegetation. Such a combination of methods
can show important temporal and spatial changes in utilization of groundwater by
vegetation. Therefore we hypothesized that species with an access to GW might
be less affected by seasonal drought but more susceptible to the lowering of the
groundwater levels. Our results indicated that plant species response to groundwater
availability varied according to the functional group and functional traits. Moreover
this variation included a different response not only in time (seasonal change) but
also in space (groundwater use heterogeneity). Both M. faya and A. longifolia,
two understory nitrogen fixing plant species presented a large range in GW use
associated with microsite GW heterogeneity. Corema was the only species where
spatial GW use heterogeneity did not change significantly the water potential pattern,
being the reasons for that change associated with other factors rather than GW
use. The only phraetophyte species, S. repens (plants that use groundwater) was
highly sensitive to changes in the hydrogeological regime. The correlations between
groundwater use to maximum water potentials determined at predawn as well as
to δ13C presented a large variation between and within the same species. There
was no correlation between δ13C and drought conditions during summer in well
adapted Mediterranean species Therefore, it is not surprising that correlations between
bulk leaf δ13C and xylem δ18O tended to be stronger in spring than in summer.
Accordingly, the studied plant responses and strategies integrated those variations and
fluctuations, limiting the functionality and the plant distribution in the ecosystems. |
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